Research ArticleDevelopment of Potentiometric Phenol Sensors by Nata de CocoMembrane on Screen-Printed Carbon Electrode

Ani Mulyasuryani and Afifah Muhimmatul Mustaghfiroh

Analytical Chemistry Laboratory Department of Chemistry Faculty of Mathematics and Natural SciencesUniversity of Brawijaya Malang Indonesia

Correspondence should be addressed to Ani Mulyasuryani mulyasuryaniubacid

Received 22 March 2019 Revised 26 June 2019 Accepted 31 July 2019 Published 19 August 2019

Academic Editor Hana Sklenarova

Copyright copy 2019 Ani Mulyasuryani and Afifah Muhimmatul Mustaghfiroh is is an open access article distributed under theCreative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium providedthe original work is properly cited

Nata de coco a bacterial cellulose as a result of coconut water fermentation is a conductive polymer with a electrical conductivityof 553 μScm and has high mechanical stability In this study nata de coco was used as a supporting membrane for the de-velopment of phenol sensors in potentiometry Nata de coco membrane containing phenol is coated on the surface of the printedcarbon electrode (screen-printed carbon electrode) e cross-sectional area of the carbon electrode coated with the membrane is15times 3mm2 while the reference electrode is AgAgCl e thickness of the electrode membrane affects the Nernstian factor eoptimum Nernstian factor is produced by 100 μm membrane thickness containing 1175 μg of phenol Measurement of phenolsolution was carried out at pH 11 in the concentration range of 10minus 8 to 10minus 2molL resulting in a Nernstian factor of418plusmn 13mVdecade e Nernstian factor increased to 557plusmn 04mVdecade if the membrane of the electrode contained 01Fe3O4 nanoparticles is sensor has been applied in the real sample of river water resulting in good accuracy and precision

1 Introduction

Phenol is one of the organic substances produced fromindustrial plants such as petroleum e high phenol con-centration in the water system can cause death in certaingroups of organisms [1] e maximum limit of phenolconcentration in the waters that is permitted based on theRegulation of the Minister of Environment of the Republicof Indonesia number 032010 is 1mgL [2] e standardmethod that has been used to determine phenol levels inwater according to SNI 06-698921-2004 is by the spectro-photometric method in which phenol is reacted with 4-aminoantipyrine to form a brownish red complex [3] In thismethod sample preparation is needed from random mea-surements carried out in the laboratory To facilitate thecontrol of phenol levels it is necessary to develop phenolsensors that are easily applied in the field

Selective membranes are one of the main componentsin the development of chemical sensors especially inpotentiometry Selective membranes are developed by

incorporating ionophores and active ingredients in apolymer such as polyvinyl chloride (PVC) Membranesmust be a conducting material PVC is a conductingmaterial due to the presence of Clminus which is polar and hasgood mechanical stability [4 5] Nata de coco is an exampleof a polar polymer because it has OH groups on theirsurface hence it can conduct electricity Meanwhile cel-lulose derived from bacteria is insoluble in water due tohydrogen bonds between adjacent hydroxyl groups [6] Inaddition bacterial cellulose has the advantage of being amembrane that has high purity small pore size of 008ndash009 μm high density low toxicity and high mechanicalstability [7 8] erefore nata de coco can be applied as amembrane in sensormanufacturese application of nata decoco as a membrane sensor has been developed for colori-metric sensors [9 10] and fluorosity sensors [11] hence it isalso possible to be applied to potentiometric sensors

Chan et al have developed phenol sensors using PVCmembranes [12] Phenol sensors have also been developedusing chitosan and cetyl trimethylammonium phenol

HindawiJournal of Analytical Methods in ChemistryVolume 2019 Article ID 4608135 8 pageshttpsdoiorg10115520194608135

(CTAPh) membranes as ionophores [13] In this study natade coco was used as a membrane To detect the analyte ionsspecifically the same ion as the analyte must be present inthe nata de coco membrane [14] Phenoxide ion which wasdeposited into the nata de coco membrane is used as theactive ion e nata de coco selective membrane is thencoated on the surface of the carbon electrode e electrodeused is a type of screen-printed electrode (SPE) consistingof a AgAgCl reference and an indicator electrode(Figure 1)

Signal (cell potential Ecell) in potentiometry is produceddue to differences in concentration on the surface of theinner membrane with the outside membrane which in-teracts with the analyte e difference in concentration willcause a potential difference which is then read compared tothe reference electrode [15] Phenol is a weak acid with a pKavalue of 994 [16] hence phenol can be detected in the formof phenoxide ions and their presence are influenced by pHAs an anion the cell potential generated in the phenol sensorrefers to the ESI anion as shown in equation (1) e 00592log [C6H5Ominus ]membrane Easy and Ereff in equation (1) areconstant thus the equation is simplified in equation (2)

Ecell 00592 log C6H5Ominus

1113858 1113859membrane

minus 00592 log C6H5Ominus

1113858 1113859analyte + Easy minus Ereff(1)

Ecell K minus 00592 log C6H5Ominus

1113858 1113859analyte (2)

where K 00592 log [C6H5Ominus ]membranendashEreff + Easy in whichEasy is a potential that is unpredictable due to membraneuniformity

e difference in phenol concentration in the analytesolution with phenol concentration in the membrane isindicated from the signal or cell potential (Ecell) emathematical function of the relationship between con-centration and signal is expressed in equation (2) which is alogarithmic equation For monovalent ions such as phenolsensor sensitivity is expressed by the Nernstian factor592mVdecade e measurement principle of the phenolicion using the nata de coco membrane is illustrated inFigure 2 (note Eb is a function of analyte concentrationbecause the phenol concentration in the membrane is fixedEb is measured and compared to the reference electrodepotential namely AgAgCl which has a fixed amount (ifusing 1M KCl solution 222mV)

Addition of metal oxide nanoparticles into membrane isknown and been reported previously e presence of metaloxide nanoparticles alters the properties of the membraneFor example the hydrophobic properties and pore size of thepolysulfone membrane can be modified by addition of aTiO2 and polyvinylpyrrolidone (PVP) mixture [17] In ourprevious work we also had successfully prepared the nata decoco membrane added with Fe3O4 on the SPCE (screen-printed carbon electrode) surface for the diazinon sensor[18] Preparation of the Fe3O4-modified electrode formeasurement of other ions or molecules in solution was alsoreported such as for ascorbic acid [19] chlorite ions [20]and nitrite ions [21]

Specifically several sensors [22] and biosensors [23 24]have been incorporating Fe3O4 nanoparticles in theirmembranes In ion selective electrodes this nanomaterial isextensively explored as the contact material or modifiedmaterials of working electrodes due to Fe3O4 because of itselectrical and hydrophobic properties [25] Fe3O4 is believedto be able to promote rapid electron transfer between theelectrode and the active site of the reaction based on itsability to adsorb electromagnetic waves [26] and its con-ductivity (800 μscm) [27]

Fe3O4 nanoparticles can also act as pseudocapacitors[28] e capacitor is a component that can store a largeelectrical charge for a while [29] Pseudocapacitors are madeto increase the capacitive process in the presence of chemicalreactions is type of capacitor requires material that canchemically store the charge with a fast redox reaction PureFe3O4 nanoparticles have a specific capacitance of 33 Fgwhile magnetite nanoparticles coated on carbon can increasespecific capacitance up to 510 Fg [30 31] Specific capaci-tance is directly proportional to the surface area and theaddition of Fe3O4 nanoparticles can increase the surfacearea e existence of an increase in specific capacitance canaccelerate load transduction so that it can increase thesensitivity of the sensor which in this study was stated as theNernstian factor

Previously we had develop a modified SPCE Ppy-SiO2for phenol determination at a concentration of 103ndash10minus 5mMwith a sensitivity of 793 μAmM [32] In this paper we arereporting the utilisation of nata de coco as membrane on thescreen-printed electrode (SPE) for phenol degradation eeffect of themembrane thickness pH of phenol solution andaddition of Fe3O4 nanoparticles into the membrane to thesensor performance was discussed All preparations andmeasurements (except the SEM analysis) were conducted atroom temperature in Chemistry Laboratory of ChemistryDepartment University of Brawijaya Indonesia

Details

Overall dimension of individualSPE 115 times 30mm (W times L)

Working electrode material carbon

Working electrode size 15times 30mm (W times L) area = 45mm2

Reference electrode material AgAgCl

Electrode connection material Ag

Quasense Co Ltd

(i)

(ii)

(iii)

(iv)

(v)

Figure 1 Illustrated SPE and specification used in this work eblack part on the left picture is the electrode coated with nata decoco

E1 EbE2EAgAgCl

Ecell

Figure 2 Illustrated measurement principle of phenol using thenata de coco membrane ( phenol in membrane phenol inthe analyte E1 Eanalyte E2 Emembrane EselEcell and Eb thepotential difference between membrane boundaries and analytes)

2 Journal of Analytical Methods in Chemistry

2 Materials and Methods

21 Materials and Instrumentations Chemicals were usedwithout further purification and were all obtained fromMerck namely phenol NaOH (NH4)2SO4 and Fe3O4nanoparticles of 50ndash100 nm Materials used in this studywere nata de coco and distilled water Laboratory tools andinstrumentations used in this study were local chopperblender magnetic stirrer BI1703 Quasense screen-printedcarbon electrode (SPCE) Sanwa CD800a potentiometerQuasense electrode connector Senz TI-13MO597 pHmeterAccumax Promicropipette Fourier-transform infrared (FT-IR) Shimadzu 8400S (4500ndash400 cmminus 1) and scanning elec-tron microscopy (SEM) FEI Inspect S50 (performed at StateUniversity of Malang Indonesia)

22 Methods

221 Preparation of Phenol Sensors Nata de coco was madeby anaerobic fermentation of coconut water in the presenceof Acetobacter xylinum for 7 days with a composition of 1 Lof coconut water 67 g of sugar 50 g (NH4)2SO4 and100mL of Acetobacter xylinum starter A 100 g of nata decoco was cut into small pieces en it was added with50mL of distilled water with pH 7 and blended using ablender for 5minutes Next the nata de coco was filtered offusing filter cloth weighed 3 g and added with 90mL ofdistilled water with pH 7 e mixture was then groundagain using a blender for 15minutes resulting in a sus-pension e suspension was then added with a 0094 gphenol in a 10mL of distilled water e mixture once wasagain stirred at room temperature using a magnetic stirrerfor 24 hours e nata de coco membrane that has beenmade was finally coated onto the carbon electrode as muchas 25 50 75 100 125 and 150 μL (depending on themembrane thickness) and dried for 30minutes at 50degC

222 Preparation of Phenol Sensor + Fe3O4 A 0094 g ofphenol was added with 01 g Fe3O4 nanoparticles and thenmixed with nata de coco suspension up to 10mL emixture is shaken with a shaker for 24 hours A total of125 μL of the mixture was coated on the surface of thecarbon electrode and dried for 30minutes at 50degC

223 Measurement of Phenol Cell Potential e indicatorelectrode was connected to the negative pole on the po-tentiometer while the AgAgCl reference electrode wasconnected to the positive pole Measurement of cell potentialof the phenol solution was carried out by dripping a phenolsolution on 50 μL on the surface of both electrodes (indicatorelectrode and reference electrode) e measurement of cellpotential was carried out consecutively from phenol con-centrations of 10minus 8ndash10minus 1M at pH 11 e cell potential wasmeasured at room temperature for 3minutes

224 Validation of Phenol Sensors Four identical phenolsensors were prepared with 100 μm nata de coco membrane

thickness containing phenol and Fe3O4 Each sensor wasused to measure 13 phenol standard solutions at pH 11 witha concentration range of 10minus 8ndash10minus 2M and one real samplewas taken from the river water Repetition of measurementswas carried out five times every five days For validation ofthe river water sample the standard addition method wasused and the calculation of sample concentration was basedon the standard curve of each repetition

225 Data Analysis A standard of deviation (SD) was usedto validate the data Analysis of variance was used in testingbetween treatments on the influence of membrane thicknesswith 6 treatments (h 6) five replications each total data 30(N 30)

3 Results and Discussion

31 Preparation of Phenol Sensor One of the advantages ofusing nata de coco as membrane is that nata de coco hasmany hydroxyl groups on their surface ese functionalgroups along with other functional groups could alter theproperties of the membrane including conductivity ehydroxyl group in nata de coco was confirmed by the broadpeak around 3200ndash3400 cmminus 1 Nata de coco used in thiswork also has the alkyl (C-H) group and carbonyl (CO)group which was indicated by the sharp peak around2900 cmminus 1 and 1650 cmminus 1 respectively In detail the infraredspectra of nata de coco are presented in Figure 3

Phenol is an OH-substituted benzene compound andthe presence of hydroxyl (minus OH) and carbonyl (CO) groupsin nata de coco allows the formation of hydrogen bondsbetween phenol and nata de coco e stirring process for24 hours is expected to result in a stronger interaction be-tween phenol and nata de coco

32 Effect of Nata de CocoMembrane2ickness e nata decoco membrane thickness is studied because it will affectmembrane uniformity and will affect the amount of Easy Inthis study the thickness of the membrane studied was 60 7080 90 100 and 110 μm e measurements of cell potentialfor each membrane thickness are shown in Figure 1 Asshown Figure 1 the cell potential is inversely proportional tolog[C6H5Ominus ] indicating that the measured sample is anionnamely phenolic ion and this corresponds to equation (2)All electrodes with various membrane thicknesses producethe identical pattern data in which the signal was increasingsignificantly in the concentration range of 10minus 2ndash10minus 8M eNernstian factor is calculated using data in Figure 4 with aconcentration range of 10minus 2ndash10minus 8M e Nernstian factorvalues at various electrodes of different thicknesses areshown in Figure 5

Sensor performance can be studied through the Nernstianfactor value For monovalent ions the theoretical Nernstianfactor is 592mVdecade Phenol sensors have a good per-formance if they produce a Nernstian factor close to thetheoretical calculation Figure 2 shows that the Nernstianfactor increased directly and proportional to the membraneelectrode thickness except at 110 μm thicknesse Nernstian

Journal of Analytical Methods in Chemistry 3

factor was insignificantly increased from thickness 100 to110μm us it was decided that the best electrodes wereproduced at 100 μm thickness with a Nernstian factor of418mVdecadee increase in the Nernst factor is caused byan increase in the phenol concentration in the membrane

As presented in Table 1 the increase in the K level(equation (2)) is straight line with the membrane thicknessis is understandable because the setting of membranethickness was done by increasing the volume of the mem-brane material coated on the surface of the carbon electrodewithin the same area is also shows that the membraneregularity (in this case the spread of active ions) is much

better if the thickness of the membrane increases untilcertain limits since its thick membrane may cause irregu-larities According to Fouskaki and Chaniotakis [33] a thickmembrane causes the membrane surface distance with the

5007501000125015001750200025003000350040001cm

20

30

40

50

60

70

80

90

100

T

337712 335591

289688

273487

164710

142915

116300111092 105885

103570

70590

61718

Selulosa (nata de coco)

Figure 3 Infrared spectra of nata de coco used in this work

ndash200ndash150ndash100

ndash500

50100150200250

0 1 2 3 4 5 6 7 8 9

60microm80microm100microm

70microm90microm110microm

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 4 Relationship between the minus log[C6H5Ominus ] with the cellpotential (Ecell) at various membrane thickness

0

10

20

30

40

50

60microm 70microm 80microm 90microm 100microm 110micromMembrane thickness

Ner

nstia

n fa

ctor

(mV

dec

ade)

Figure 5 Relationship curve between membrane thickness andNernst factor

Table 1 e value of K and membrane conductivity for eachmembrane thickness

No Membrane thickness(μm)

K(mV)

Electrical conductivity (μScm)

1 60 minus 210 5432 70 minus 205 5453 80 minus 187 5474 90 minus 164 5515 100 minus 144 5696 110 minus 135 561

4 Journal of Analytical Methods in Chemistry

electrode to be farther away so that the sensor responsebecomes slower and this was likely to occur at the electrodewith a membrane thickness of 110 μm hence the data wereless consistent as indicated by the high SD value

ere is a slight increase in membrane electrical con-ductivity for each increase in membrane thickness (Table 1)is is because in thicker membrane the amount of water ishigher and this also results in a higher membrane electricalconductivity and capacitance [34] In addition the increasein membrane thickness is directly proportional to theamount of phenol in the membrane Because phenol is apolar compound the electrical conductivity increases withincreasing phenol concentration However the increase inelectrical conductivity has little effect on the Nernstianfactor which is a sensor performance indicator or sensorsensitivityus other effort needs to be done to increase theNernstian factor significantly and to get closer Nernstianfactor to the theoretical value

33 Sensor Performance One of the factors that can affectthe performance of the sensor is pH considering thatphenolic ions can only form perfectly (α1) at pHge 10(pKa 99) For this reason the pH of the phenol solutionwas adjusted to pH 11 by using the 001M carbonate bufferand using NaOH solution separately Figure 6 shows theEcell difference obtained using different buffers at pH 11 Asshown in Figure 6 the linear concentration was obtained inthe range 10minus 5ndash10minus 8M for the carbonate buffer is resultleaves uncertainty does the presence of CO3

minus 2 and HCO3minus

ions block the interaction of phenolic ions with themembrane e purpose of using the 001M carbonatebuffer is to increase the activity of the solution so that it isexpected to improve the sensor performance but the datawere not inconclusive It is possibly due to high concen-tration of the carbonate buffer which is 100 times higherthan the NaOH concentration in phenol solution In ad-dition CO3

minus 2 and HCO3minus ions geometrically have a larger

size than Na+ and OHminus ions thus it is possible that theCO3

minus 2 and HCO3minus ions inhibit the interaction of phenolic

ions with the membraneIn Figure 6 it can also be seen that the signal generated

from the NaOH solution is greater than the signal gen-erated from the 001M carbonate buffer e interaction ofthe electrode interface with the electrolyte solution canproduce a double layer of electricity on the surface of theelectrode producing a capacitor [35ndash37] In the nonstirringprocess the velocity of the capacitor formation depends onthe mobility of the ions naturally Mobility of OHminus

(2064 times10minus 8 m2sminus 1vminus 1) is higher than the mobility of CO32minus

(718 times10ndash8 m2sminus 1vminus 1) hence OHminus ions have a greaterability to get to the surface of the electrode [36] is cancause the capacitance on the electrode surface to be higherin NaOH solution than in a carbonate buffer solution ifobserved at the same time is concluded the signalproduced in the NaOH solution is greater

34AdditionofFe3O4Nanoparticles Another factor that canaffect sensor performance is the nature of the membrane

including selective membranes and conductive membranesIn an effort to increase membrane conductivity Fe3O4nanoparticles were added e SEM images of the sensorsurface with and without addition of Fe3O4 nanoparticles arepresented in Figure 7 Both images show significant dif-ference in which nata de coco has homogeneous fiberysurface whereas due to addition of Fe3O4 nanoparticlessome of the surface area were covered with the granuleshape is also indicates that the Fe3O4 has been in-corporated into the membrane Based on SEM imagesFe3O4 makes the electrode surface to become rougher anduneven which eventually affects the sensor performanceeelectrode surface profile can affect the amount of Easy [15]thus affecting the value of K

Furthermore it is needed to investigate whether thenata de coco membrane is a selective membrane or notwithout the addition of phenolic ions hence it is nec-essary to also make a sensor with a membrane withoutphenol Figure 8 shows a comparison of the potential cell(signal) produced by three electrodes made of differentmembranes namely electrodes with membranes made ofnata de coco only (A) made of nata de coco and phenol(B) and made of nata de coco phenol and Fe3O4 (C) eelectrode membrane thickness of A B and C was set equalto 100 μm

35 Validation of Phenol Sensors Phenol sensor validationwas carried out for 20 days using 4 identical sensors Basedon the five repetitions the average signal of four sensors andphenol concentration are showing the same profile as seenin Figure 9 Sensitivity which was indicated by the value ofthe Nernstian factor tends to decrease in less than 5except for the 5th repetition in which the decrease was up to7 Based on Table 2 it can be seen that phenol sensors havea good sensitivity for up to 4 times measurement day 15(each sensor was used to measure 64 standard phenol so-lutions and samples) Although the sensitivity of the sensortends to decrease in each repetition the accuracy of thesensor (or reproducibility of the measurement results) of the4 sensors is reasonably very good it can be seen from the

100

50

0

ndash50

ndash100

ndash150

ndash2001 2 3 4 5 6 7 8 9

ndashLog[C6H5Ondash]

E cel

l (m

V)

Carbonate bufferNaOH

Figure 6 Potential cell of phenol solution at pH 11 in carbonateand in NaOH buffers

Journal of Analytical Methods in Chemistry 5

RSD which is not more than 1 even if the measurementresults are repeated for 5 times

e measurement accuracy can be observed from therecovery of standard samples added to river water samples

is was done so that the environmental conditions of thestandard phenol electrolyte are the same as that of riverwater samples As shown in Table 3 the average recovery is9350 for 4 μM standard phenol and 9325 for 8 μM (thedata are the average of the measurement obtained from 4phenol sensors with 4 repetitions each) Based on Tables 2and 3 it can be highlighted that phenol sensors producedfrom the nata de coco and Fe3O4 membrane have a goodprecision and accuracy

4 Conclusions

Nata de coco can be used as a membrane material in a phenolsensor selective membrane by potentiometry Membranethickness of up to 100 μm increases membrane electricalconductivity and this corresponds to an increase in theNernstian factor e highest Nernstian factor was producedby electrodes with a membrane of 100 μm Setting the pH ofthe phenol solution to 11 using NaOH solution produces abetter signal than using the carbonate buffer of 001M eaddition of 01 Fe3O4 nanoparticles in the electrodemembrane improves the sensor performance In the

10μmtimes10kD44NL

(a) (b)

Figure 7 SEM images (mag 10000x) of the sensor surface without (a) and with (b) addition of Fe3O4 nanoparticles

y = 4171x ndash 135

y = 5572x ndash 166

ndash200ndash150ndash100

ndash500

50100150200250300350

0 1 2 3 4 5 6 7 8 9

ABC

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 8 Signal data profile on changes in phenol concentration ineach membrane electrodes Electrodes with membranes made ofnata de coco only (A) nata de coco + phenol (B) and nata decoco + phenol + Fe3O4 (C)

400350300250200

100150

0ndash50

ndash100

50

0 1 2 3 4 5 6 7 8 9ndashLog[C6H5Ondash]

E cel

l (m

V)

IIIIII

IVV

Figure 9 Profile of Ecell toward phenol concentrations at pH 11Average signal data on first measurement (I) second repetition (II)third repetition (III) fourth repetition (IV) and fifth repetition (V)

Table 2 e average of Nernstian factor of 4 phenol sensors

Days to Nernstian factor (mVdecade) RSD () Bias ()1 5571plusmn 043 077 mdash5 5443plusmn 027 050 23010 5375plusmn 012 022 35215 5342plusmn 048 090 41220 5186plusmn 012 023 691

Table 3 Phenol concentration in river water sample and the re-covery percentage

Solution Phenol concentration(μM)

Recovery()

Sample 160plusmn 004 mdashSample + 4 μM phenolstandard 534plusmn 004 9350plusmn 075

Sample + 8 μM phenolstandard 906plusmn 004 9325plusmn 044

6 Journal of Analytical Methods in Chemistry

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

2 Materials and Methods

21 Materials and Instrumentations Chemicals were usedwithout further purification and were all obtained fromMerck namely phenol NaOH (NH4)2SO4 and Fe3O4nanoparticles of 50ndash100 nm Materials used in this studywere nata de coco and distilled water Laboratory tools andinstrumentations used in this study were local chopperblender magnetic stirrer BI1703 Quasense screen-printedcarbon electrode (SPCE) Sanwa CD800a potentiometerQuasense electrode connector Senz TI-13MO597 pHmeterAccumax Promicropipette Fourier-transform infrared (FT-IR) Shimadzu 8400S (4500ndash400 cmminus 1) and scanning elec-tron microscopy (SEM) FEI Inspect S50 (performed at StateUniversity of Malang Indonesia)

22 Methods

221 Preparation of Phenol Sensors Nata de coco was madeby anaerobic fermentation of coconut water in the presenceof Acetobacter xylinum for 7 days with a composition of 1 Lof coconut water 67 g of sugar 50 g (NH4)2SO4 and100mL of Acetobacter xylinum starter A 100 g of nata decoco was cut into small pieces en it was added with50mL of distilled water with pH 7 and blended using ablender for 5minutes Next the nata de coco was filtered offusing filter cloth weighed 3 g and added with 90mL ofdistilled water with pH 7 e mixture was then groundagain using a blender for 15minutes resulting in a sus-pension e suspension was then added with a 0094 gphenol in a 10mL of distilled water e mixture once wasagain stirred at room temperature using a magnetic stirrerfor 24 hours e nata de coco membrane that has beenmade was finally coated onto the carbon electrode as muchas 25 50 75 100 125 and 150 μL (depending on themembrane thickness) and dried for 30minutes at 50degC

222 Preparation of Phenol Sensor + Fe3O4 A 0094 g ofphenol was added with 01 g Fe3O4 nanoparticles and thenmixed with nata de coco suspension up to 10mL emixture is shaken with a shaker for 24 hours A total of125 μL of the mixture was coated on the surface of thecarbon electrode and dried for 30minutes at 50degC

223 Measurement of Phenol Cell Potential e indicatorelectrode was connected to the negative pole on the po-tentiometer while the AgAgCl reference electrode wasconnected to the positive pole Measurement of cell potentialof the phenol solution was carried out by dripping a phenolsolution on 50 μL on the surface of both electrodes (indicatorelectrode and reference electrode) e measurement of cellpotential was carried out consecutively from phenol con-centrations of 10minus 8ndash10minus 1M at pH 11 e cell potential wasmeasured at room temperature for 3minutes

224 Validation of Phenol Sensors Four identical phenolsensors were prepared with 100 μm nata de coco membrane

thickness containing phenol and Fe3O4 Each sensor wasused to measure 13 phenol standard solutions at pH 11 witha concentration range of 10minus 8ndash10minus 2M and one real samplewas taken from the river water Repetition of measurementswas carried out five times every five days For validation ofthe river water sample the standard addition method wasused and the calculation of sample concentration was basedon the standard curve of each repetition

225 Data Analysis A standard of deviation (SD) was usedto validate the data Analysis of variance was used in testingbetween treatments on the influence of membrane thicknesswith 6 treatments (h 6) five replications each total data 30(N 30)

3 Results and Discussion

31 Preparation of Phenol Sensor One of the advantages ofusing nata de coco as membrane is that nata de coco hasmany hydroxyl groups on their surface ese functionalgroups along with other functional groups could alter theproperties of the membrane including conductivity ehydroxyl group in nata de coco was confirmed by the broadpeak around 3200ndash3400 cmminus 1 Nata de coco used in thiswork also has the alkyl (C-H) group and carbonyl (CO)group which was indicated by the sharp peak around2900 cmminus 1 and 1650 cmminus 1 respectively In detail the infraredspectra of nata de coco are presented in Figure 3

Phenol is an OH-substituted benzene compound andthe presence of hydroxyl (minus OH) and carbonyl (CO) groupsin nata de coco allows the formation of hydrogen bondsbetween phenol and nata de coco e stirring process for24 hours is expected to result in a stronger interaction be-tween phenol and nata de coco

32 Effect of Nata de CocoMembrane2ickness e nata decoco membrane thickness is studied because it will affectmembrane uniformity and will affect the amount of Easy Inthis study the thickness of the membrane studied was 60 7080 90 100 and 110 μm e measurements of cell potentialfor each membrane thickness are shown in Figure 1 Asshown Figure 1 the cell potential is inversely proportional tolog[C6H5Ominus ] indicating that the measured sample is anionnamely phenolic ion and this corresponds to equation (2)All electrodes with various membrane thicknesses producethe identical pattern data in which the signal was increasingsignificantly in the concentration range of 10minus 2ndash10minus 8M eNernstian factor is calculated using data in Figure 4 with aconcentration range of 10minus 2ndash10minus 8M e Nernstian factorvalues at various electrodes of different thicknesses areshown in Figure 5

Sensor performance can be studied through the Nernstianfactor value For monovalent ions the theoretical Nernstianfactor is 592mVdecade Phenol sensors have a good per-formance if they produce a Nernstian factor close to thetheoretical calculation Figure 2 shows that the Nernstianfactor increased directly and proportional to the membraneelectrode thickness except at 110 μm thicknesse Nernstian

Journal of Analytical Methods in Chemistry 3

factor was insignificantly increased from thickness 100 to110μm us it was decided that the best electrodes wereproduced at 100 μm thickness with a Nernstian factor of418mVdecadee increase in the Nernst factor is caused byan increase in the phenol concentration in the membrane

As presented in Table 1 the increase in the K level(equation (2)) is straight line with the membrane thicknessis is understandable because the setting of membranethickness was done by increasing the volume of the mem-brane material coated on the surface of the carbon electrodewithin the same area is also shows that the membraneregularity (in this case the spread of active ions) is much

better if the thickness of the membrane increases untilcertain limits since its thick membrane may cause irregu-larities According to Fouskaki and Chaniotakis [33] a thickmembrane causes the membrane surface distance with the

5007501000125015001750200025003000350040001cm

20

30

40

50

60

70

80

90

100

T

337712 335591

289688

273487

164710

142915

116300111092 105885

103570

70590

61718

Selulosa (nata de coco)

Figure 3 Infrared spectra of nata de coco used in this work

ndash200ndash150ndash100

ndash500

50100150200250

0 1 2 3 4 5 6 7 8 9

60microm80microm100microm

70microm90microm110microm

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 4 Relationship between the minus log[C6H5Ominus ] with the cellpotential (Ecell) at various membrane thickness

0

10

20

30

40

50

60microm 70microm 80microm 90microm 100microm 110micromMembrane thickness

Ner

nstia

n fa

ctor

(mV

dec

ade)

Figure 5 Relationship curve between membrane thickness andNernst factor

Table 1 e value of K and membrane conductivity for eachmembrane thickness

No Membrane thickness(μm)

K(mV)

Electrical conductivity (μScm)

1 60 minus 210 5432 70 minus 205 5453 80 minus 187 5474 90 minus 164 5515 100 minus 144 5696 110 minus 135 561

4 Journal of Analytical Methods in Chemistry

electrode to be farther away so that the sensor responsebecomes slower and this was likely to occur at the electrodewith a membrane thickness of 110 μm hence the data wereless consistent as indicated by the high SD value

ere is a slight increase in membrane electrical con-ductivity for each increase in membrane thickness (Table 1)is is because in thicker membrane the amount of water ishigher and this also results in a higher membrane electricalconductivity and capacitance [34] In addition the increasein membrane thickness is directly proportional to theamount of phenol in the membrane Because phenol is apolar compound the electrical conductivity increases withincreasing phenol concentration However the increase inelectrical conductivity has little effect on the Nernstianfactor which is a sensor performance indicator or sensorsensitivityus other effort needs to be done to increase theNernstian factor significantly and to get closer Nernstianfactor to the theoretical value

33 Sensor Performance One of the factors that can affectthe performance of the sensor is pH considering thatphenolic ions can only form perfectly (α1) at pHge 10(pKa 99) For this reason the pH of the phenol solutionwas adjusted to pH 11 by using the 001M carbonate bufferand using NaOH solution separately Figure 6 shows theEcell difference obtained using different buffers at pH 11 Asshown in Figure 6 the linear concentration was obtained inthe range 10minus 5ndash10minus 8M for the carbonate buffer is resultleaves uncertainty does the presence of CO3

minus 2 and HCO3minus

ions block the interaction of phenolic ions with themembrane e purpose of using the 001M carbonatebuffer is to increase the activity of the solution so that it isexpected to improve the sensor performance but the datawere not inconclusive It is possibly due to high concen-tration of the carbonate buffer which is 100 times higherthan the NaOH concentration in phenol solution In ad-dition CO3

minus 2 and HCO3minus ions geometrically have a larger

size than Na+ and OHminus ions thus it is possible that theCO3

minus 2 and HCO3minus ions inhibit the interaction of phenolic

ions with the membraneIn Figure 6 it can also be seen that the signal generated

from the NaOH solution is greater than the signal gen-erated from the 001M carbonate buffer e interaction ofthe electrode interface with the electrolyte solution canproduce a double layer of electricity on the surface of theelectrode producing a capacitor [35ndash37] In the nonstirringprocess the velocity of the capacitor formation depends onthe mobility of the ions naturally Mobility of OHminus

(2064 times10minus 8 m2sminus 1vminus 1) is higher than the mobility of CO32minus

(718 times10ndash8 m2sminus 1vminus 1) hence OHminus ions have a greaterability to get to the surface of the electrode [36] is cancause the capacitance on the electrode surface to be higherin NaOH solution than in a carbonate buffer solution ifobserved at the same time is concluded the signalproduced in the NaOH solution is greater

34AdditionofFe3O4Nanoparticles Another factor that canaffect sensor performance is the nature of the membrane

including selective membranes and conductive membranesIn an effort to increase membrane conductivity Fe3O4nanoparticles were added e SEM images of the sensorsurface with and without addition of Fe3O4 nanoparticles arepresented in Figure 7 Both images show significant dif-ference in which nata de coco has homogeneous fiberysurface whereas due to addition of Fe3O4 nanoparticlessome of the surface area were covered with the granuleshape is also indicates that the Fe3O4 has been in-corporated into the membrane Based on SEM imagesFe3O4 makes the electrode surface to become rougher anduneven which eventually affects the sensor performanceeelectrode surface profile can affect the amount of Easy [15]thus affecting the value of K

Furthermore it is needed to investigate whether thenata de coco membrane is a selective membrane or notwithout the addition of phenolic ions hence it is nec-essary to also make a sensor with a membrane withoutphenol Figure 8 shows a comparison of the potential cell(signal) produced by three electrodes made of differentmembranes namely electrodes with membranes made ofnata de coco only (A) made of nata de coco and phenol(B) and made of nata de coco phenol and Fe3O4 (C) eelectrode membrane thickness of A B and C was set equalto 100 μm

35 Validation of Phenol Sensors Phenol sensor validationwas carried out for 20 days using 4 identical sensors Basedon the five repetitions the average signal of four sensors andphenol concentration are showing the same profile as seenin Figure 9 Sensitivity which was indicated by the value ofthe Nernstian factor tends to decrease in less than 5except for the 5th repetition in which the decrease was up to7 Based on Table 2 it can be seen that phenol sensors havea good sensitivity for up to 4 times measurement day 15(each sensor was used to measure 64 standard phenol so-lutions and samples) Although the sensitivity of the sensortends to decrease in each repetition the accuracy of thesensor (or reproducibility of the measurement results) of the4 sensors is reasonably very good it can be seen from the

100

50

0

ndash50

ndash100

ndash150

ndash2001 2 3 4 5 6 7 8 9

ndashLog[C6H5Ondash]

E cel

l (m

V)

Carbonate bufferNaOH

Figure 6 Potential cell of phenol solution at pH 11 in carbonateand in NaOH buffers

Journal of Analytical Methods in Chemistry 5

RSD which is not more than 1 even if the measurementresults are repeated for 5 times

e measurement accuracy can be observed from therecovery of standard samples added to river water samples

is was done so that the environmental conditions of thestandard phenol electrolyte are the same as that of riverwater samples As shown in Table 3 the average recovery is9350 for 4 μM standard phenol and 9325 for 8 μM (thedata are the average of the measurement obtained from 4phenol sensors with 4 repetitions each) Based on Tables 2and 3 it can be highlighted that phenol sensors producedfrom the nata de coco and Fe3O4 membrane have a goodprecision and accuracy

4 Conclusions

Nata de coco can be used as a membrane material in a phenolsensor selective membrane by potentiometry Membranethickness of up to 100 μm increases membrane electricalconductivity and this corresponds to an increase in theNernstian factor e highest Nernstian factor was producedby electrodes with a membrane of 100 μm Setting the pH ofthe phenol solution to 11 using NaOH solution produces abetter signal than using the carbonate buffer of 001M eaddition of 01 Fe3O4 nanoparticles in the electrodemembrane improves the sensor performance In the

10μmtimes10kD44NL

(a) (b)

Figure 7 SEM images (mag 10000x) of the sensor surface without (a) and with (b) addition of Fe3O4 nanoparticles

y = 4171x ndash 135

y = 5572x ndash 166

ndash200ndash150ndash100

ndash500

50100150200250300350

0 1 2 3 4 5 6 7 8 9

ABC

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 8 Signal data profile on changes in phenol concentration ineach membrane electrodes Electrodes with membranes made ofnata de coco only (A) nata de coco + phenol (B) and nata decoco + phenol + Fe3O4 (C)

400350300250200

100150

0ndash50

ndash100

50

0 1 2 3 4 5 6 7 8 9ndashLog[C6H5Ondash]

E cel

l (m

V)

IIIIII

IVV

Figure 9 Profile of Ecell toward phenol concentrations at pH 11Average signal data on first measurement (I) second repetition (II)third repetition (III) fourth repetition (IV) and fifth repetition (V)

Table 2 e average of Nernstian factor of 4 phenol sensors

Days to Nernstian factor (mVdecade) RSD () Bias ()1 5571plusmn 043 077 mdash5 5443plusmn 027 050 23010 5375plusmn 012 022 35215 5342plusmn 048 090 41220 5186plusmn 012 023 691

Table 3 Phenol concentration in river water sample and the re-covery percentage

Solution Phenol concentration(μM)

Recovery()

Sample 160plusmn 004 mdashSample + 4 μM phenolstandard 534plusmn 004 9350plusmn 075

Sample + 8 μM phenolstandard 906plusmn 004 9325plusmn 044

6 Journal of Analytical Methods in Chemistry

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

factor was insignificantly increased from thickness 100 to110μm us it was decided that the best electrodes wereproduced at 100 μm thickness with a Nernstian factor of418mVdecadee increase in the Nernst factor is caused byan increase in the phenol concentration in the membrane

As presented in Table 1 the increase in the K level(equation (2)) is straight line with the membrane thicknessis is understandable because the setting of membranethickness was done by increasing the volume of the mem-brane material coated on the surface of the carbon electrodewithin the same area is also shows that the membraneregularity (in this case the spread of active ions) is much

better if the thickness of the membrane increases untilcertain limits since its thick membrane may cause irregu-larities According to Fouskaki and Chaniotakis [33] a thickmembrane causes the membrane surface distance with the

5007501000125015001750200025003000350040001cm

20

30

40

50

60

70

80

90

100

T

337712 335591

289688

273487

164710

142915

116300111092 105885

103570

70590

61718

Selulosa (nata de coco)

Figure 3 Infrared spectra of nata de coco used in this work

ndash200ndash150ndash100

ndash500

50100150200250

0 1 2 3 4 5 6 7 8 9

60microm80microm100microm

70microm90microm110microm

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 4 Relationship between the minus log[C6H5Ominus ] with the cellpotential (Ecell) at various membrane thickness

0

10

20

30

40

50

60microm 70microm 80microm 90microm 100microm 110micromMembrane thickness

Ner

nstia

n fa

ctor

(mV

dec

ade)

Figure 5 Relationship curve between membrane thickness andNernst factor

Table 1 e value of K and membrane conductivity for eachmembrane thickness

No Membrane thickness(μm)

K(mV)

Electrical conductivity (μScm)

1 60 minus 210 5432 70 minus 205 5453 80 minus 187 5474 90 minus 164 5515 100 minus 144 5696 110 minus 135 561

4 Journal of Analytical Methods in Chemistry

electrode to be farther away so that the sensor responsebecomes slower and this was likely to occur at the electrodewith a membrane thickness of 110 μm hence the data wereless consistent as indicated by the high SD value

ere is a slight increase in membrane electrical con-ductivity for each increase in membrane thickness (Table 1)is is because in thicker membrane the amount of water ishigher and this also results in a higher membrane electricalconductivity and capacitance [34] In addition the increasein membrane thickness is directly proportional to theamount of phenol in the membrane Because phenol is apolar compound the electrical conductivity increases withincreasing phenol concentration However the increase inelectrical conductivity has little effect on the Nernstianfactor which is a sensor performance indicator or sensorsensitivityus other effort needs to be done to increase theNernstian factor significantly and to get closer Nernstianfactor to the theoretical value

33 Sensor Performance One of the factors that can affectthe performance of the sensor is pH considering thatphenolic ions can only form perfectly (α1) at pHge 10(pKa 99) For this reason the pH of the phenol solutionwas adjusted to pH 11 by using the 001M carbonate bufferand using NaOH solution separately Figure 6 shows theEcell difference obtained using different buffers at pH 11 Asshown in Figure 6 the linear concentration was obtained inthe range 10minus 5ndash10minus 8M for the carbonate buffer is resultleaves uncertainty does the presence of CO3

minus 2 and HCO3minus

ions block the interaction of phenolic ions with themembrane e purpose of using the 001M carbonatebuffer is to increase the activity of the solution so that it isexpected to improve the sensor performance but the datawere not inconclusive It is possibly due to high concen-tration of the carbonate buffer which is 100 times higherthan the NaOH concentration in phenol solution In ad-dition CO3

minus 2 and HCO3minus ions geometrically have a larger

size than Na+ and OHminus ions thus it is possible that theCO3

minus 2 and HCO3minus ions inhibit the interaction of phenolic

ions with the membraneIn Figure 6 it can also be seen that the signal generated

from the NaOH solution is greater than the signal gen-erated from the 001M carbonate buffer e interaction ofthe electrode interface with the electrolyte solution canproduce a double layer of electricity on the surface of theelectrode producing a capacitor [35ndash37] In the nonstirringprocess the velocity of the capacitor formation depends onthe mobility of the ions naturally Mobility of OHminus

(2064 times10minus 8 m2sminus 1vminus 1) is higher than the mobility of CO32minus

(718 times10ndash8 m2sminus 1vminus 1) hence OHminus ions have a greaterability to get to the surface of the electrode [36] is cancause the capacitance on the electrode surface to be higherin NaOH solution than in a carbonate buffer solution ifobserved at the same time is concluded the signalproduced in the NaOH solution is greater

34AdditionofFe3O4Nanoparticles Another factor that canaffect sensor performance is the nature of the membrane

including selective membranes and conductive membranesIn an effort to increase membrane conductivity Fe3O4nanoparticles were added e SEM images of the sensorsurface with and without addition of Fe3O4 nanoparticles arepresented in Figure 7 Both images show significant dif-ference in which nata de coco has homogeneous fiberysurface whereas due to addition of Fe3O4 nanoparticlessome of the surface area were covered with the granuleshape is also indicates that the Fe3O4 has been in-corporated into the membrane Based on SEM imagesFe3O4 makes the electrode surface to become rougher anduneven which eventually affects the sensor performanceeelectrode surface profile can affect the amount of Easy [15]thus affecting the value of K

Furthermore it is needed to investigate whether thenata de coco membrane is a selective membrane or notwithout the addition of phenolic ions hence it is nec-essary to also make a sensor with a membrane withoutphenol Figure 8 shows a comparison of the potential cell(signal) produced by three electrodes made of differentmembranes namely electrodes with membranes made ofnata de coco only (A) made of nata de coco and phenol(B) and made of nata de coco phenol and Fe3O4 (C) eelectrode membrane thickness of A B and C was set equalto 100 μm

35 Validation of Phenol Sensors Phenol sensor validationwas carried out for 20 days using 4 identical sensors Basedon the five repetitions the average signal of four sensors andphenol concentration are showing the same profile as seenin Figure 9 Sensitivity which was indicated by the value ofthe Nernstian factor tends to decrease in less than 5except for the 5th repetition in which the decrease was up to7 Based on Table 2 it can be seen that phenol sensors havea good sensitivity for up to 4 times measurement day 15(each sensor was used to measure 64 standard phenol so-lutions and samples) Although the sensitivity of the sensortends to decrease in each repetition the accuracy of thesensor (or reproducibility of the measurement results) of the4 sensors is reasonably very good it can be seen from the

100

50

0

ndash50

ndash100

ndash150

ndash2001 2 3 4 5 6 7 8 9

ndashLog[C6H5Ondash]

E cel

l (m

V)

Carbonate bufferNaOH

Figure 6 Potential cell of phenol solution at pH 11 in carbonateand in NaOH buffers

Journal of Analytical Methods in Chemistry 5

RSD which is not more than 1 even if the measurementresults are repeated for 5 times

e measurement accuracy can be observed from therecovery of standard samples added to river water samples

is was done so that the environmental conditions of thestandard phenol electrolyte are the same as that of riverwater samples As shown in Table 3 the average recovery is9350 for 4 μM standard phenol and 9325 for 8 μM (thedata are the average of the measurement obtained from 4phenol sensors with 4 repetitions each) Based on Tables 2and 3 it can be highlighted that phenol sensors producedfrom the nata de coco and Fe3O4 membrane have a goodprecision and accuracy

4 Conclusions

Nata de coco can be used as a membrane material in a phenolsensor selective membrane by potentiometry Membranethickness of up to 100 μm increases membrane electricalconductivity and this corresponds to an increase in theNernstian factor e highest Nernstian factor was producedby electrodes with a membrane of 100 μm Setting the pH ofthe phenol solution to 11 using NaOH solution produces abetter signal than using the carbonate buffer of 001M eaddition of 01 Fe3O4 nanoparticles in the electrodemembrane improves the sensor performance In the

10μmtimes10kD44NL

(a) (b)

Figure 7 SEM images (mag 10000x) of the sensor surface without (a) and with (b) addition of Fe3O4 nanoparticles

y = 4171x ndash 135

y = 5572x ndash 166

ndash200ndash150ndash100

ndash500

50100150200250300350

0 1 2 3 4 5 6 7 8 9

ABC

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 8 Signal data profile on changes in phenol concentration ineach membrane electrodes Electrodes with membranes made ofnata de coco only (A) nata de coco + phenol (B) and nata decoco + phenol + Fe3O4 (C)

400350300250200

100150

0ndash50

ndash100

50

0 1 2 3 4 5 6 7 8 9ndashLog[C6H5Ondash]

E cel

l (m

V)

IIIIII

IVV

Figure 9 Profile of Ecell toward phenol concentrations at pH 11Average signal data on first measurement (I) second repetition (II)third repetition (III) fourth repetition (IV) and fifth repetition (V)

Table 2 e average of Nernstian factor of 4 phenol sensors

Days to Nernstian factor (mVdecade) RSD () Bias ()1 5571plusmn 043 077 mdash5 5443plusmn 027 050 23010 5375plusmn 012 022 35215 5342plusmn 048 090 41220 5186plusmn 012 023 691

Table 3 Phenol concentration in river water sample and the re-covery percentage

Solution Phenol concentration(μM)

Recovery()

Sample 160plusmn 004 mdashSample + 4 μM phenolstandard 534plusmn 004 9350plusmn 075

Sample + 8 μM phenolstandard 906plusmn 004 9325plusmn 044

6 Journal of Analytical Methods in Chemistry

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

electrode to be farther away so that the sensor responsebecomes slower and this was likely to occur at the electrodewith a membrane thickness of 110 μm hence the data wereless consistent as indicated by the high SD value

ere is a slight increase in membrane electrical con-ductivity for each increase in membrane thickness (Table 1)is is because in thicker membrane the amount of water ishigher and this also results in a higher membrane electricalconductivity and capacitance [34] In addition the increasein membrane thickness is directly proportional to theamount of phenol in the membrane Because phenol is apolar compound the electrical conductivity increases withincreasing phenol concentration However the increase inelectrical conductivity has little effect on the Nernstianfactor which is a sensor performance indicator or sensorsensitivityus other effort needs to be done to increase theNernstian factor significantly and to get closer Nernstianfactor to the theoretical value

33 Sensor Performance One of the factors that can affectthe performance of the sensor is pH considering thatphenolic ions can only form perfectly (α1) at pHge 10(pKa 99) For this reason the pH of the phenol solutionwas adjusted to pH 11 by using the 001M carbonate bufferand using NaOH solution separately Figure 6 shows theEcell difference obtained using different buffers at pH 11 Asshown in Figure 6 the linear concentration was obtained inthe range 10minus 5ndash10minus 8M for the carbonate buffer is resultleaves uncertainty does the presence of CO3

minus 2 and HCO3minus

ions block the interaction of phenolic ions with themembrane e purpose of using the 001M carbonatebuffer is to increase the activity of the solution so that it isexpected to improve the sensor performance but the datawere not inconclusive It is possibly due to high concen-tration of the carbonate buffer which is 100 times higherthan the NaOH concentration in phenol solution In ad-dition CO3

minus 2 and HCO3minus ions geometrically have a larger

size than Na+ and OHminus ions thus it is possible that theCO3

minus 2 and HCO3minus ions inhibit the interaction of phenolic

ions with the membraneIn Figure 6 it can also be seen that the signal generated

from the NaOH solution is greater than the signal gen-erated from the 001M carbonate buffer e interaction ofthe electrode interface with the electrolyte solution canproduce a double layer of electricity on the surface of theelectrode producing a capacitor [35ndash37] In the nonstirringprocess the velocity of the capacitor formation depends onthe mobility of the ions naturally Mobility of OHminus

(2064 times10minus 8 m2sminus 1vminus 1) is higher than the mobility of CO32minus

(718 times10ndash8 m2sminus 1vminus 1) hence OHminus ions have a greaterability to get to the surface of the electrode [36] is cancause the capacitance on the electrode surface to be higherin NaOH solution than in a carbonate buffer solution ifobserved at the same time is concluded the signalproduced in the NaOH solution is greater

34AdditionofFe3O4Nanoparticles Another factor that canaffect sensor performance is the nature of the membrane

including selective membranes and conductive membranesIn an effort to increase membrane conductivity Fe3O4nanoparticles were added e SEM images of the sensorsurface with and without addition of Fe3O4 nanoparticles arepresented in Figure 7 Both images show significant dif-ference in which nata de coco has homogeneous fiberysurface whereas due to addition of Fe3O4 nanoparticlessome of the surface area were covered with the granuleshape is also indicates that the Fe3O4 has been in-corporated into the membrane Based on SEM imagesFe3O4 makes the electrode surface to become rougher anduneven which eventually affects the sensor performanceeelectrode surface profile can affect the amount of Easy [15]thus affecting the value of K

Furthermore it is needed to investigate whether thenata de coco membrane is a selective membrane or notwithout the addition of phenolic ions hence it is nec-essary to also make a sensor with a membrane withoutphenol Figure 8 shows a comparison of the potential cell(signal) produced by three electrodes made of differentmembranes namely electrodes with membranes made ofnata de coco only (A) made of nata de coco and phenol(B) and made of nata de coco phenol and Fe3O4 (C) eelectrode membrane thickness of A B and C was set equalto 100 μm

35 Validation of Phenol Sensors Phenol sensor validationwas carried out for 20 days using 4 identical sensors Basedon the five repetitions the average signal of four sensors andphenol concentration are showing the same profile as seenin Figure 9 Sensitivity which was indicated by the value ofthe Nernstian factor tends to decrease in less than 5except for the 5th repetition in which the decrease was up to7 Based on Table 2 it can be seen that phenol sensors havea good sensitivity for up to 4 times measurement day 15(each sensor was used to measure 64 standard phenol so-lutions and samples) Although the sensitivity of the sensortends to decrease in each repetition the accuracy of thesensor (or reproducibility of the measurement results) of the4 sensors is reasonably very good it can be seen from the

100

50

0

ndash50

ndash100

ndash150

ndash2001 2 3 4 5 6 7 8 9

ndashLog[C6H5Ondash]

E cel

l (m

V)

Carbonate bufferNaOH

Figure 6 Potential cell of phenol solution at pH 11 in carbonateand in NaOH buffers

Journal of Analytical Methods in Chemistry 5

RSD which is not more than 1 even if the measurementresults are repeated for 5 times

e measurement accuracy can be observed from therecovery of standard samples added to river water samples

is was done so that the environmental conditions of thestandard phenol electrolyte are the same as that of riverwater samples As shown in Table 3 the average recovery is9350 for 4 μM standard phenol and 9325 for 8 μM (thedata are the average of the measurement obtained from 4phenol sensors with 4 repetitions each) Based on Tables 2and 3 it can be highlighted that phenol sensors producedfrom the nata de coco and Fe3O4 membrane have a goodprecision and accuracy

4 Conclusions

Nata de coco can be used as a membrane material in a phenolsensor selective membrane by potentiometry Membranethickness of up to 100 μm increases membrane electricalconductivity and this corresponds to an increase in theNernstian factor e highest Nernstian factor was producedby electrodes with a membrane of 100 μm Setting the pH ofthe phenol solution to 11 using NaOH solution produces abetter signal than using the carbonate buffer of 001M eaddition of 01 Fe3O4 nanoparticles in the electrodemembrane improves the sensor performance In the

10μmtimes10kD44NL

(a) (b)

Figure 7 SEM images (mag 10000x) of the sensor surface without (a) and with (b) addition of Fe3O4 nanoparticles

y = 4171x ndash 135

y = 5572x ndash 166

ndash200ndash150ndash100

ndash500

50100150200250300350

0 1 2 3 4 5 6 7 8 9

ABC

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 8 Signal data profile on changes in phenol concentration ineach membrane electrodes Electrodes with membranes made ofnata de coco only (A) nata de coco + phenol (B) and nata decoco + phenol + Fe3O4 (C)

400350300250200

100150

0ndash50

ndash100

50

0 1 2 3 4 5 6 7 8 9ndashLog[C6H5Ondash]

E cel

l (m

V)

IIIIII

IVV

Figure 9 Profile of Ecell toward phenol concentrations at pH 11Average signal data on first measurement (I) second repetition (II)third repetition (III) fourth repetition (IV) and fifth repetition (V)

Table 2 e average of Nernstian factor of 4 phenol sensors

Days to Nernstian factor (mVdecade) RSD () Bias ()1 5571plusmn 043 077 mdash5 5443plusmn 027 050 23010 5375plusmn 012 022 35215 5342plusmn 048 090 41220 5186plusmn 012 023 691

Table 3 Phenol concentration in river water sample and the re-covery percentage

Solution Phenol concentration(μM)

Recovery()

Sample 160plusmn 004 mdashSample + 4 μM phenolstandard 534plusmn 004 9350plusmn 075

Sample + 8 μM phenolstandard 906plusmn 004 9325plusmn 044

6 Journal of Analytical Methods in Chemistry

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

RSD which is not more than 1 even if the measurementresults are repeated for 5 times

e measurement accuracy can be observed from therecovery of standard samples added to river water samples

is was done so that the environmental conditions of thestandard phenol electrolyte are the same as that of riverwater samples As shown in Table 3 the average recovery is9350 for 4 μM standard phenol and 9325 for 8 μM (thedata are the average of the measurement obtained from 4phenol sensors with 4 repetitions each) Based on Tables 2and 3 it can be highlighted that phenol sensors producedfrom the nata de coco and Fe3O4 membrane have a goodprecision and accuracy

4 Conclusions

Nata de coco can be used as a membrane material in a phenolsensor selective membrane by potentiometry Membranethickness of up to 100 μm increases membrane electricalconductivity and this corresponds to an increase in theNernstian factor e highest Nernstian factor was producedby electrodes with a membrane of 100 μm Setting the pH ofthe phenol solution to 11 using NaOH solution produces abetter signal than using the carbonate buffer of 001M eaddition of 01 Fe3O4 nanoparticles in the electrodemembrane improves the sensor performance In the

10μmtimes10kD44NL

(a) (b)

Figure 7 SEM images (mag 10000x) of the sensor surface without (a) and with (b) addition of Fe3O4 nanoparticles

y = 4171x ndash 135

y = 5572x ndash 166

ndash200ndash150ndash100

ndash500

50100150200250300350

0 1 2 3 4 5 6 7 8 9

ABC

ndashLog[C6H5Ondash]

E cel

l (m

V)

Figure 8 Signal data profile on changes in phenol concentration ineach membrane electrodes Electrodes with membranes made ofnata de coco only (A) nata de coco + phenol (B) and nata decoco + phenol + Fe3O4 (C)

400350300250200

100150

0ndash50

ndash100

50

0 1 2 3 4 5 6 7 8 9ndashLog[C6H5Ondash]

E cel

l (m

V)

IIIIII

IVV

Figure 9 Profile of Ecell toward phenol concentrations at pH 11Average signal data on first measurement (I) second repetition (II)third repetition (III) fourth repetition (IV) and fifth repetition (V)

Table 2 e average of Nernstian factor of 4 phenol sensors

Days to Nernstian factor (mVdecade) RSD () Bias ()1 5571plusmn 043 077 mdash5 5443plusmn 027 050 23010 5375plusmn 012 022 35215 5342plusmn 048 090 41220 5186plusmn 012 023 691

Table 3 Phenol concentration in river water sample and the re-covery percentage

Solution Phenol concentration(μM)

Recovery()

Sample 160plusmn 004 mdashSample + 4 μM phenolstandard 534plusmn 004 9350plusmn 075

Sample + 8 μM phenolstandard 906plusmn 004 9325plusmn 044

6 Journal of Analytical Methods in Chemistry

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

concentration range of 10minus 8ndash10minus 2M the Nernstian factorincreases from 418plusmn 13 to 557plusmn 04mVdecadeis sensorwhich was prepared from nata de coco and Fe3O4 membraneshows good precision and accuracy

Data Availability

All data used to support the finding of this study are availablefrom the corresponding author on reasonable request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this article

Acknowledgments

We would like to thank Brawijaya University Indonesia forproviding the laboratory facilities and technical support

References

[1] X Dong Q Hong L He X Jiang and S Li ldquoCharacterizationof phenol-degrading bacterial strains isolated from naturalsoilrdquo International Biodeterioration amp Biodegradation vol 62no 3 pp 257ndash262 2008

[2] Kementerian Lingkungan HidupndashRepublik Indonesia PPNomor 3 Tahun 2010 Baku Mutu Air Limbah Bagi KawasanIndustri KLH Jakarta Indonesia 2010

[3] Badan Standarisasi NasionalndashRepublik Indonesia Air DanAir Limbah-Bagian 21 Cara Uji Kadar Fenol Secara Spek-trofotometri (SNI 06-698921-2004) BSN Tangerang Indo-nesia 2004

[4] E T Eftimie S Catalina and M Alexandra ldquoIon selectivepolymeric membranes for chemical sensor Irdquo Proceedings of theRecent Researches in Energy Environment and Sustainable De-velopment vol 1 pp 161ndash165 2012 httpspdfssemanticscholarorg54deeb82d55b999099d557cd7e14df89d2fa1abcpdf

[5] M A Simon and R P Kusy ldquoe molecular physical andmechanical properties of highly plasticized poly(vinyl chlo-ride) membranesrdquo Polymer vol 34 no 24 pp 5106ndash51151993

[6] I Sulaeva U Henniges T Rosenau and A Potthast ldquoBac-terial cellulose as a material for wound treatment propertiesandmodifications A reviewrdquo Biotechnology Advances vol 33no 8 pp 1547ndash1571 2015

[7] M S Dayal and J M Catchmark ldquoMechanical and structuralproperty analysis of bacterial cellulose compositesrdquo Carbo-hydrate Polymers vol 144 no 6 pp 447ndash453 2016

[8] Q Yang H Ma Z Dai et al ldquoImproved thermal and me-chanical properties of bacterial cellulose with the introductionof collagenrdquo Cellulose vol 24 no 9 pp 3777ndash3787 2017

[9] S Pirsa and S Chavoshizadeh ldquoDesign of an optical sensor forethylene based on nanofiber bacterial cellulose film and itsapplication for determination of banana storage timerdquoPolymers for Advanced Technologies vol 29 no 5pp 1385ndash1393 2018

[10] P Milindanuth and P Pisitsak ldquoA novel colorimetric sensorbased on rhodamine-B derivative and bacterial cellulose forthe detection of Cu(II) ions in waterrdquo Materials Chemistryand Physics vol 216 no 8 pp 325ndash331 2018

[11] S Abbasi-Moayed H Golmohammadi and M R Hormozi-Nezhad ldquoA nanopaper-based artificial tongue a ratiometric

fluorescent sensor array on bacterial nanocellulose forchemical discrimination applicationsrdquo Nanoscale vol 10no 5 pp 2492ndash2502 2018

[12] W H Chan A W M Lee and M S Wong ldquoSome ob-servations on the determination of phenol using ion selectiveelectrodesrdquo Microchemical Journal vol 40 no 3 pp 322ndash327 1989

[13] A A Tyas Z Aini andW S Wari ldquoDetermination of phenolin water using phenol sensorrdquo Jurnal Penelitian Saintekvol 20 no 1 pp 53ndash56 2015

[14] E Pretsch M Badertscher M Welti T MaruizumiW E Morf andW Simon ldquoDesign features of ionophores forion selective electrodesrdquo Pure and Applied Chemistry vol 60no 4 pp 567ndash574 1988

[15] E Bakker and Y Qin ldquoElectrochemical sensorsrdquo AnalyticalChemistry vol 78 no 12 pp 3965ndash3984 2006

[16] Z Rappoport 2e Chemistry of Phenols John Wiley amp SonsNew Jersey NJ USA 2003

[17] N N Said F Hamzah N A Ramlee and N N Yunus ldquoeeffect of TiO2 particles addition on the characteristics ofpolysulfone membranerdquo International Journal on AdvancedScience Engineering and Information Technology vol 8 no 3pp 825ndash831 2018

[18] D Pramana A Mulyasuryani and R Triandi TjahjantoldquoMembranes of nata de coco-nanoparticles Fe3O4 for diazi-non sensorsrdquo 2e Journal of Pure and Applied ChemistryResearch vol 7 no 3 pp 275ndash281 2018

[19] F G Nejad H Beitollahi and S Shakeri ldquoMagnetic corendashshell Fe3O4SiO2graphene nanocomposite modified carbonpaste electrode for voltametric determinantion of ascorbicacid in the presence of L-cysteinrdquoAnalytical and BioanalyticalElectrochemistry vol 8 no 3 pp 318ndash328 2016

[20] M H Mashhadizadeh and H Jeilanpour ldquoVoltammeric in-vestigation of ketotifen using carbon paste electrode modifiedby magnetic core-shell Fe3O4TMSPT nanoparticlesrdquo Ana-lytical and Bioanalytical Electrochemistry vol 6 pp 308ndash3202014

[21] E M Rosida A Mulyasuryani and R T Tjahjanto ldquoMod-ification of screen printed carbon electrode (SPCE) withFe3O4 for the determination of nitrite (NO2-) in squarewavevoltammetryrdquo Molekul vol 12 no 2 pp 139ndash145 2017

[22] Y Yang Y Zhang J-C Shen H Yang Z-G Zhou andS-P Yang ldquoA highly selective magnetic sensor with func-tionalized FeFe3O4 nanoparticles for detection of Pb2+rdquoChinese Chemical Letters vol 27 no 6 pp 891ndash895 2016

[23] N Sanaeifar M Rabiee M Abdolrahim M TahririD Vashaee and L Tayebi ldquoA novel electrochemical biosensorbased on Fe3O4 nanoparticles-polyvinyl alcohol composite forsensitive detection of glucoserdquo Analytical Biochemistryvol 519 pp 19ndash26 2017

[24] W Zhang X Li R Zou et al ldquoMultifunctional glucosebiosensors from Fe3O4 nanoparticles modified chitosangraphene nanocompositesrdquo Scientific Reports vol 5 ArticleID 11129 pp 1ndash9 2015

[25] T Yin and W Qin ldquoApplications of nanomaterials in po-tentiometric sensorsrdquo TrAC Trends in Analytical Chemistryvol 51 pp 79ndash86 2013

[26] A Kaushik R Khan P R Solanki et al ldquoIron oxidenanoparticlesndashchitosan composite based glucose biosensorrdquoBiosensors and Bioelectronics vol 24 no 4 pp 676ndash683 2008

[27] O Yavuz M K Ram and M Aldissi ldquoChapter 9 Electro-magnetic applications of conducting and nanocompositematerialsrdquo in 2e New Frontiers of Organic and Composite

Journal of Analytical Methods in Chemistry 7

Nanotechnology V Erokhin M K Ram and O Yavus Edspp 435ndash475 Elsevier Oxford UK 2008

[28] P Tipsawat U Wongpratat S Phumying N ChanlekK Chokprasombat and S Maensiri ldquoMagnetite (Fe3O4)nanoparticles synthesis characterization and electrochemicalpropertiesrdquo Applied Surface Science vol 446 pp 287ndash2922018

[29] M Chanif and S Sarwito ldquoAnalisa pengaruh penambahankapasitor terhadap proses pengisian baterai wahana bawahlautrdquo Jurnal Teknik ITS vol 3 no 1 pp 1ndash6 2014

[30] N-L Wu S-Y Wang C-Y Han D-S Wu and L-R ShiueldquoElectrochemical capacitor of magnetite in aqueous electro-lytesrdquo Journal of Power Sources vol 113 no 1 pp 173ndash1782003

[31] S-YWang K-C Ho S-L Kuo and N-LWu ldquoInvestigationon capacitance mechanisms of Fe[sub 3]O[sub 4] electro-chemical capacitorsrdquo Journal of 2e Electrochemical Societyvol 153 no 1 p A75 2006

[32] E Pratiwi A Mulyasuryani and A Sabarudin ldquoModificationof screen printed carbon electrode (SPCE) with polypyrrole(Ppy)-SiO2 for phenol determinationrdquo 2e Journal of Pureand Applied Chemistry Research vol 7 no 1 pp 12ndash18 2018

[33] M Fouskaki and N A Chaniotakis ldquoick membrane solidcontact ion selective electrode for the detection of lead atpicomolar levelsrdquo Analytical Chemistry vol 77 no 6pp 1780ndash1784 2005

[34] A R Rebelo A J Archer X Chen C Liu G Yang andY Liu ldquoDehydration of bacterial cellulose and the watercontent effects on its viscoelastic and electrochemical prop-ertiesrdquo Science and Technology of Advanced Materials vol 19no 1 pp 203ndash211 2018

[35] W Huang A K Diallo J L Dailey K Besar and H E KatzldquoElectrochemical processes and mechanistic aspects of field-effect sensors for biomolecules (a review)rdquo Journal of Ma-terials Chemistry C vol 3 no 25 pp 6445ndash6470 2015

[36] F Faridbod A Shafaat and M R Ganjali ldquoConductingpolymer all solid state potentiometric sensor for the tramadolassayrdquo International Journal of Electrochemical Sciencevol 11 no 12 pp 10123ndash10134 2016

[37] T Ghosh H-J Chung and J Rieger ldquoAll-solid-state sodium-selective electrode with a solid contact of chitosanprussianblue nanocompositerdquo Sensors vol 17 no 11 pp 1ndash17 2017

8 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom