Research Article Molecular Modeling of Acidic Treated PSTM ...downloads.hindawi.com/journals/ijps/2014/260378.pdfResearch Article Molecular Modeling of Acidic Treated PSTM-3T Polymer

Research ArticleMolecular Modeling of Acidic Treated PSTM-3TPolymer for Removal of Heavy Metal Ions by Experimental andComputational Studies

Natsagdorj Narantsogt1 Gunchin Burmaa2 Adiya Perlee-Oidov1

Nyamdorj Shurkhuu3 and Namsrai Javkhlantugs3

1 School of Natural Sciences Mongolian State University of Education 210648 Ulaanbaatar Mongolia2 Institute of Chemistry and Chemical Technology Mongolian Academy of Science 13330 Ulaanbaatar Mongolia3 Center for Nanoscience and Nanotechnology School of Engineering and Applied Sciences National University of MongoliaPO Box 46290 Room 127 Main building University Street 1 14201 Ulaanbaatar Mongolia

Correspondence should be addressed to Namsrai Javkhlantugs javkhlantugsnumedumn

Received 18 December 2013 Revised 7 March 2014 Accepted 9 March 2014 Published 26 May 2014

Academic Editor Peng He

Copyright copy 2014 Natsagdorj Narantsogt et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The synthesized poly[NN1015840-bis(3-silsesquioxanilpropyl)-thiocarbamide] (PSTM-3T) was used and the surface morphology andmicrostructure of it were analyzed by scanning electron microscopy with energy dispersive spectrometer (SEMEDS) Themolecular structure change of the PSTM-3T polymer of the PSTM-3T after treatment by acidic solution with different pHs wasrevealed using FT-IR experiments and ab initio calculations with density functional theory method The sorption efficiency of theheavy metal ions depends on the molecular structure change of PSTM-3T after treatment of different pH aqueous solutions Afterthe treatment of acidic solution (pH= 2) of PSTM-3T the polymer formed the tautomer state to increase the sorption efficiency forchromate ion For the increment of pH value for acidic solution the PSTM-3T polymer was dissociated to increase the sorptionefficiency for copper ion

1 Introduction

Industrial wastewater pollution from heavy metals is a majorconcern in developing countries The industries produce thewastewater containing heavy metal ions with high concen-trations There exist many treatment techniques which havebeen developed such as chemical precipitation [1] adsorption[2 3] and ion exchange [4]

Copper has been one of the most widely used metals forcenturies and is mainly employed in electronic and electricalelectroplating and mining industries The organic-inorganicpolymeric sorbents are known for their excellent surfacecharacteristics for the effective adsorption of metals Forexample the preconcentration and separation of elementsby using the chelating silicon-organic polymers have beenreported [5ndash7] However most of chelating silicon polymers

are used for preconcentration and determination of noblemetal ions and their synthesis of silica organic polymersusually takes a long time and synthetic process is complicated

One of the other surface active simple polymersis poly[NN1015840-bis(3-silsesquioxanilpropyl)-thiocarbamide](PSTM-3T) which was synthesized [8] and investigatedfor determination of noble metals of gold platinum andpalladium [9] Previously we revealed the adsorptionkinetics for removal of Cu(II) and Cr(VI) ions from thewastewater using PSTM-3T polymer [10 11] In this studywe revealed the molecular structure change of PSTM-3T forsorption mechanism of heavy metal ions after treatment bydifferent acidic solutions using frontier-transform infraredspectrophotometer (FT-IR) and ab initio calculations indetail

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2014 Article ID 260378 6 pageshttpdxdoiorg1011552014260378

2 International Journal of Polymer Science

2 Materials and Methods

21 Synthesis of PSTM-3T poly[NN1015840-bis(3-silsesquioxanil-propyl)-thiocarbamide] (PSTM-3T) polymer (Scheme 1) wassynthesized from silicon-organic monomer of NN1015840-bis(3-triethoxysilylpropyl)-thiocarbamide by hydrolytic polycon-densation reaction in aqueous media with pH = 8-9 atthe boiling temperature [8] The synthesized PSTM-3T wascharacterized by scanning electron microscopy with energydispersive spectrometer (SEMEDS) and frontier-transforminfrared (FT-IR) spectroscopy

22 Scanning Electron Microscopy (SEM) and Energy Disper-sive Spectrometer (EDS) Thesurfacemorphology andmicro-structure were examined by scanning electron microscopy(Philips XL30 The Netherlands) The powdered sampleswere mounted onto double-sided carbon tapes and sputter-coated with palladium using a Cressington sputter coater108A (Cressington Scientific Instruments Watford UK)TheSEM images were taken on a Philips XL30 field emission gunSEM (FEI Company Hillsboro OR USA) and EDS resultswere obtained using the built-in EDAX Genesis software

23 Frontier-Transform Infrared (FT-IR) Spectroscopy Thechemical bond frequencies of functional groups of polymerbefore and after treatment by acidic solutions were analyzedby using frontier-transform infrared (FT-IR) spectropho-tometer (IRPrestige-21 Shimadzu Tokyo Japan) The pow-dered samples were mixed with KBr to make the pellets TheFT-IR spectra were obtained with frequency range of 4000ndash400 cmminus1

24 Ultraviolet Visible (UV-Vis) Spectrophotometer Theamounts of metal ions in an initial solution and aftertreatment by polymer were analyzed by using ultravioletvisible (UV-vis) spectrophotometer (U-1000 HITACHITokyo Japan) The samples were prepared by mixing withthe complexing reagent as diethyl dithiocarbamate forcopper ion [12] and 15-diphenylcarbazide for chromateion [13] which forms a color with metal ion After beingfiltered all samples were analyzed using quartz cuvette witha path length of 10mm at wavelength of 430 nm for copperion and 540 nm for chromate ion The spectrophotometermeasurement for sorption kinetics of the PSTM-3T atdifferent pHs was carried out with stirrerhot plate (CorningPC-620D) after treatment of 005 g PSTM-3T into 50mL(20mgL of copper and 60mgL chromate ions) solution

25 Computational Calculation Procedure The molecularstructures of PSTM-3T polymer were modeled at differentpH conditionswith consideration of tautomerization and dis-sociation Geometries of all the considered model molecules(Figure 1) in this study were fully optimized by using densityfunctional theory (DFT)with Beckersquos three-parameter hybridexchange function [14] and the Lee-Yang-Parr correlationfunction (B3LYP) [15] and with the 6-31G(d p) basis set [16]method in Gaussian 03 package [17] Vibrational frequenciesand absolute IR intensities of optimized structures were

Sindash(CH2)3ndashNHndashCndashNHndash(CH2)3ndashSiO15n=

SO15

Scheme 1 Representation of molecular structure of PSTM-3Tpolymer

10120583m

Figure 1 SEM image of synthesized PSTM-3T polymer

investigated with 6-311G(d p) level All the convergent preci-sions were the system default values and the all calculationswere carried out on the standard lab-level workstation withAMD Opteron 285 dual core CPU Data visualization wascarried out using GaussView 30 [18]

3 Results and Discussion

31 Characterization of PSTM-3T Polymer The details ofchemical composition of PSTM-3T by EDS analysis are givenin Table 1 The major elements of the sample verified thePSTM-3TpolymerThe elemental analysis showed the similarresults with theoretically calculated contents of synthesizedtitle polymer as formula of C

7H14N2O3SSi2(Scheme 1) The

SEM was performed on an irregular and porous surface(Figure 1) which indicates high surface areas of 490m2g with353 cm3g total pore volume

The functional groups were identified using FT-IR exper-iment and the spectrum is shown in Figure 2 In Figure 2the observable IR signals for PSTM-3T were 58057 and69241 cmminus1 forC-S 156041 337350 and 338893 cmminus1 forN-H and 163178 cmminus1 for C-NThe IR signals were similar withthe group frequencies [19] In this study the model of PSTM-3T (Figure 3(a)) was investigated using the density functionalB3LYP method with 6-311G(d p) basis set (Table 2) All thevalues have relative deviation less than 53 (Table 2) and thetheoretical values are in good agreement with experimentalvalues the same as previous other reports [20]

32 Sorption of Heavy Metal Ions The solution pH is one ofthemost important factors for heavymetal sorption from theaqueous solution Sorption of copper and chromate ions wasrevealed at various pH conditions and the sorption strengthsare shown in Figure 4 The fraction of sorption of copperion as determined by the removal of copper ion percentage

International Journal of Polymer Science 3

Table 1 Chemical composition of PSTM-3T and after treatmentinto ion solutions

Elements Weight []PSTM-3T Cu(II) Cr(VI)

C 3694 3433 3742N 1423 971 773O 2316 2267 2166Si 1840 1300 2175S 710 1051 1117Cu 052Cr 026

Table 2The comparison of experimental (in Figure 2) and theoret-ical frequencies of PSTM-3TThe percentage of relative deviation ofmodel in different frequencies is shown in parenthesis

Groups Wavenumbers [1cm]Δ []

Exp Cal

CS 58057 56264 minus30969241 72857 +522

NH156041 154281 minus113337350 355203 +529338893 356054 +506

CN 163178 155677 minus401

relative to initial concentration by PSTM-3T at various pHswas calculated as (1)

119865 =(1198600minus 119860119905)

1198600

(1)

where 1198600and 119860

119905are the initial and time absorbance of

the copper ion From Figure 4(a) the removal efficiency ofcopper ion at pH = 5 is clearly seen higher than at other lowerpH conditions The equilibrium amounts of copper ion ontoPSTM-3T surface at different pH conditions were calculatedas (2)

119876119890=(1198620minus 119862119890) 119881

119898 (2)

where 119876119890(mgg) is adsorbed equilibrium amount of the ion

per unit mass of PSTM-3T polymer 1198620and 119862

119890are initial and

equilibrium ion concentration (mgL) respectively 119881 is thevolume of solution and 119898 is the mass (g) of the PSTM-3Tpolymer

The equilibrium amounts of chromate ion onto PSTM-3T surface were investigated at different pH conditions whichare shown in Figure 4(b) From Figure 4(b) the removal ofchromate ion at pH = 2 can be seen higher than at other pHconditions

33 Molecular Modeling at Different pHs The EDS analysisafter treatment of PSTM-3T into copper and chromate ionsolutions at pH5 and pH2 respectively was analyzed andthese pH conditions were higher removal efficiencies foreach ion which were discussed in previous section (Figure 4)

5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

20658

337350

(ndashN

H)

338893

(ndashN

H)

163178

(ndashCN

)156041

(ndashN

H)

69241

(ndashCS

)58057

(ndashCS

)

Figure 2 FT-IR spectra of PSTM-3T polymer

H

HH

HH

HH

H H H HH

HHHHC

C CC

CC

C

S

N N

(a)

HH

HH

H

HH

HH

HHH

H

H

H

C C CC C

CC

S

NN

(b)

HH

H

H

H

HH H

HH

HH

H

HH

CC

CCC

S

NN

(c)

Figure 3 Optimized molecular model structures of PSTM-3Tpolymer before (a) and after treatment by pH = 5 (b) and pH = 2 (c)solutions Carbon hydrogen nitrogen and sulfur atoms are shownas gray silver blue and yellow ball representations respectively

The copper and chromium atoms were obtained in PSTM-3T polymer using EDS elemental analysis after treatment ofPSTM-3T into ion solutions and the weight percentage ofthem was shown in Table 1

The FT-IR spectra of PSTM-3T after treatment by acidicsolutions are shown in Figure 5 In Figure 5(a) the IR signalsfor PSTM-3T at pH5 were found at 55357 and 66544 cmminus1for C-S 155848 and 330020 cmminus1 for N-H and 163371 cmminus1for C-N

The functional group from protonated and unproto-nated states depends on the solution pH values Thereforewe considered the additional two models of the disso-ciated (Figure 3(b) Scheme 2) and tautomer (Figure 3(c)


30

25

20

15

10

5

00 50 100 150 200 250 300

pH2

pH3

pH4

pH5

Frac

tion

of ad

sorp

tion

F(

)

Time (min)

Qe = 7mggat pH = 5

(a)

40

35

30

25

20

15

10

5

02 4 6 8 10

Am

ount

at eq

uilib

rium

Qe

(mg

g)

pH

Qe = 373mggat pH = 2

(b)

Figure 4 Sorption efficiency of copper ion (a) and equilibrium amount of chromate ion per unit mass of polymer (b) at different pHs

Abso

rban

ce

5001000150020002500300035004000

Wavenumbers (1cm)

206190

330020

(ndashN

H)

155848

(ndashN

H)

163371

(ndashCN

)

66544

(ndashCS

)55357

(ndashCS

)

(a)

5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

341400

(ndashN

H)

156041

(ndashN

H)

163564

(ndashCN

)

60372

(ndashCS

)49185

(ndashCS

)(b)

Figure 5 FT-IR spectrum of PSTM-3T polymer after treatment by pH = 5 (a) and pH = 2 (b) acidic solutions

Scheme 2) states and calculated the frequencies of these twomodels which are shown in Tables 3 and 4 The model ofdissociated state of PSTM-3T (Figure 3(b) Scheme 2) wasinvestigated using the density functional B3LYPmethod with6-311G(d p) level The major values have relative deviationless than 65 (Table 3) and the theoretical values are ingood agreement with experimental values In Figure 5(a) thefrequency of 206190 cmminus1 was obtained experimentally Alsoin spectra of PSTM-3T polymer (Figure 2) the frequencyof 20658 cmminus1 for C=S state was obtained the same asat pH = 5 Previously Grebenev et al investigated OC=Swith H

2 HD and D

2complexes using high-resolution IR

spectroscopy and found that themain differences between thespectra of them are near the frequency around 20610 cmminus1[21] We calculated single molecule in vacuum thereforethe frequency of interbond frequency was not obtainedtheoretically

Tautomer state Dissociated state

SH

pH2 pH5

minusH+

ndashR ndash(CH2)3ndashSiO15

RndashNHndashCndashNHndashR lArrrArr RndashNHndashC=NndashR ⟹ RndashNHndashC=NndashR

=

S Sminus

ndashndash

Scheme 2 Representation of molecular model structures of tau-tomer and dissociated states

For sorption of chromate ion at pH = 2 Figure 5(b)showed that the IR signals for PSTM-3T were found at49185 and 60372 cmminus1 for C-S 156041 and 341400 cmminus1for N-H and 163529 cmminus1 for C-N The model of tautomerstate of PSTM-3T (Figure 3(c) Scheme 2) was investigatedusing the density functional B3LYP method with 6-311G(dp) level All the values have relative deviation less than 52(Table 4) and the theoretical values are in good agreement


Table 3 The comparison of experimental (in Figure 5) and theo-retical (in Figure 3(b)) frequencies of PSTM-3T after treatment bynitric acid (pH = 5) solution The percentage of relative deviation ofmodel in different frequencies is shown in parenthesis

Groups Wavenumbers [1cm]Δ []Exp Cal

CS 55357 58238 +52066544 69299 +414

NH 155848 152808 minus195330020 357594 +836

Inter 206190CN 163371 152808 minus647

Table 4 The comparison of experimental (in Figure 5) and the-oretical (in Figure 3(c)) frequencies of PSTM-3T after treatmentby hydrochloric acid (pH = 2) solution The percentage of relativedeviation of model in different frequencies is shown in parenthesis


Exp Cal

CS 49185 51748 +52160372 60319 minus009

NH 156041 148339 minus494341400 354976 +398

SH 270003CN 163564 168672 +312

with experimental values Theoretically the frequency offunctional group of ndashSHwas obtained as 270003 cmminus1 whichwas not determined by FT-IR experiment because itmay havevery weak absorbance in nature

Finally the PSTM-3T polymer forms dissociated statewith thiolate ion when the highest sorption for copper ionoccurs at pH = 5 The copper ion strongly interacts withopposite charge of thiolate ions for sorption efficiency Thetautomer state of polymer with ndashSH group at pH = 2 mayactivate the reduction reaction for chromate ion

4 Conclusion

Themolecular structure change of the PSTM-3T polymer forremoval of heavy metal ions of the PSTM-3T after treatmentby acidic solution with different pHs was clearly determinedusing FT-IR experiments and ab initio calculations Afterthe treatment of acidic solution (pH = 2) of PSTM-3T thepolymer formed the tautomer state to increase the sorptionefficiency for chromate ion For the increment of pH valuefor acidic solution the PSTM-3T polymer was dissociatedto increase the sorption efficiency for copper ion Finallydecrement of pH value may increase the sorption efficiencyfor metal anions by reduction reaction

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors are grateful to the National University of Mon-golia and Yokohama National University for their help underthe Research Agreement between them for the calculationsNamsrai Javkhlantugs thanks for the part of calculationsThe Asian Research Center in Mongolia and the KoreanFoundation for Advanced Studies within the framework ofthe Project no 1 (2014-2015)

References

[1] MMMatlock B S Howerton andD A Atwood ldquoIrreversibleprecipitation of mercury and leadrdquo Journal of Hazardous Mate-rials vol 84 no 1 pp 73ndash82 2001

[2] D Mohan and S Chander ldquoRemoval and recovery of metalions from acid mine drainage using lignite-a low cost sorbentrdquoJournal of Hazardous Materials vol 137 no 3 pp 1545ndash15532006

[3] VKGupta and S Sharma ldquoRemoval of cadmiumand zinc fromaqueous solutions using red mudrdquo Environmental Science andTechnology vol 36 no 16 pp 3612ndash3617 2002

[4] V J Inglezakis M A Stylianou D Gkantzou and M DLoizidou ldquoRemoval of Pb(II) from aqueous solutions by usingclinoptilolite and bentonite as adsorbentsrdquo Desalination vol210 no 1ndash3 pp 248ndash256 2007

[5] R K Sharma ldquoDesign synthesis and application of chelatingpolymers for separation and determination of trace and toxicmetal ions A green analytical methodrdquo Pure and AppliedChemistry vol 73 no 1 pp 181ndash186 2001

[6] M Zougagh J M Cano Pavon and A Garcia De TorresldquoChelating sorbents based on silica gel and their application inatomic spectrometryrdquo Analytical and Bioanalytical Chemistryvol 381 no 6 pp 1103ndash1113 2005

[7] M E Sears ldquoChelation Harnessing and enhancing heavymetaldetoxificationmdasha reviewrdquoTheScientificWorld Journal vol 2013Article ID 219840 13 pages 2013

[8] M G Voronkov N N Vlasova Y H Pozhidaev A EPestunovich and A I Kirillov ldquoHigh effective complicit andampelite-poly[NN1015840-bis(3-silsesquiocsanilpropyl)-thiocarbam-ide]rdquo Doklady Akademii Nauk SSSR vol 320 no 3 pp658ndash662 1991 (Russian)

[9] Y PozhidaevNVlasova I Vasilyeva andMVoronkov ldquoDeter-mination of noble metals in rocks and ores using adsorbentPSTM-3Trdquo Advanced Science Letters vol 19 no 2 pp 615ndash6182013

[10] N Narantsogt G Burmaa O Nasantogtokh and A Perlee-Oidov ldquoAdsorption kinetics for the removal of copper(II) fromaqueous solution by adsorbent PSTM-3TrdquoMongolian Journal ofChemistry vol 12 pp 1ndash6 2011

[11] G Burmaa N Narantsogt O Nasantogtokh and Perlee-OidovldquoChromium(VI) sorption from aqueous solution by silicon-organic sorbent contaiting thicarbamide groupsrdquo MongolianJournal of Chemistry and Chemical Engineering vol 1 pp 7ndash122012

[12] G A Shar and M I Bhanger ldquoSpectrophotometric deter-mination of copper (II) with diethyldithiocarbamate in poly-oxyethylenedodecylether (Brij-35)mediardquo Journal of the Chem-ical Society of Pakistan vol 24 no 3 pp 185ndash189 2002


[13] M Noroozifar and M Khorasani-Motlagh ldquoSpecific extractionof chromium as tetrabutylammonium-chromate and spec-trophotometric determination by diphenylcarbazide specia-tion of chromium in effluent streamsrdquo Analytical Sciences vol19 no 5 pp 705ndash708 2003

[14] A D Becke ldquoDensity-functional thermochemistry IIIThe roleof exact exchangerdquoThe Journal of Chemical Physics vol 98 no7 pp 5648ndash5652 1993

[15] C Lee W Yang and R G Parr ldquoDevelopment of the Colle-Salvetti correlation-energy formula into a functional of theelectron densityrdquo Physical Review B vol 37 no 2 pp 785ndash7891988

[16] W J Hehre L Radom P R Schleyer and J A Pople Ab InitioMolecular Orbital Theory John Wiley amp Sons New York NYUSA 1987

[17] M J Frisch G W Trucks H B Schlegel et al Gaussian 03Revision C01 Gaussian Inc Wallingford Conn USA 2004

[18] A Frish R D Dennington II T A Keith et al GaussViewVersion 41 Gaussian Inc Wallingford Conn USA 2007

[19] J Coates ldquoInterpretation of infrared spectra a practicalapproachrdquo in Encyclopedia of Analytical Chemistry R A Mey-ers Ed pp 10815ndash10837 Jonh Wiley amp Sons Chichester UK2004

[20] M Pousti M Abbaszadeh and M S Iashkenari ldquoA combinedexperimental and theoretical studies on molecular structureand vibrational spectra of polyaniline and polyanilinesilvernanocompositerdquo Synthetic Metals vol 183 pp 63ndash68 2013

[21] S Grebenev B G Sartakov J P Toennies and A F VilesovldquoHigh-resolution infrared spectra of the OCS-H2 -HD and -D2 van der Waals complexes in liquid helium dropletsrdquo Journalof Chemical Physics vol 118 no 19 pp 8656ndash8670 2003

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2 Materials and Methods

21 Synthesis of PSTM-3T poly[NN1015840-bis(3-silsesquioxanil-propyl)-thiocarbamide] (PSTM-3T) polymer (Scheme 1) wassynthesized from silicon-organic monomer of NN1015840-bis(3-triethoxysilylpropyl)-thiocarbamide by hydrolytic polycon-densation reaction in aqueous media with pH = 8-9 atthe boiling temperature [8] The synthesized PSTM-3T wascharacterized by scanning electron microscopy with energydispersive spectrometer (SEMEDS) and frontier-transforminfrared (FT-IR) spectroscopy

22 Scanning Electron Microscopy (SEM) and Energy Disper-sive Spectrometer (EDS) Thesurfacemorphology andmicro-structure were examined by scanning electron microscopy(Philips XL30 The Netherlands) The powdered sampleswere mounted onto double-sided carbon tapes and sputter-coated with palladium using a Cressington sputter coater108A (Cressington Scientific Instruments Watford UK)TheSEM images were taken on a Philips XL30 field emission gunSEM (FEI Company Hillsboro OR USA) and EDS resultswere obtained using the built-in EDAX Genesis software

23 Frontier-Transform Infrared (FT-IR) Spectroscopy Thechemical bond frequencies of functional groups of polymerbefore and after treatment by acidic solutions were analyzedby using frontier-transform infrared (FT-IR) spectropho-tometer (IRPrestige-21 Shimadzu Tokyo Japan) The pow-dered samples were mixed with KBr to make the pellets TheFT-IR spectra were obtained with frequency range of 4000ndash400 cmminus1

24 Ultraviolet Visible (UV-Vis) Spectrophotometer Theamounts of metal ions in an initial solution and aftertreatment by polymer were analyzed by using ultravioletvisible (UV-vis) spectrophotometer (U-1000 HITACHITokyo Japan) The samples were prepared by mixing withthe complexing reagent as diethyl dithiocarbamate forcopper ion [12] and 15-diphenylcarbazide for chromateion [13] which forms a color with metal ion After beingfiltered all samples were analyzed using quartz cuvette witha path length of 10mm at wavelength of 430 nm for copperion and 540 nm for chromate ion The spectrophotometermeasurement for sorption kinetics of the PSTM-3T atdifferent pHs was carried out with stirrerhot plate (CorningPC-620D) after treatment of 005 g PSTM-3T into 50mL(20mgL of copper and 60mgL chromate ions) solution

25 Computational Calculation Procedure The molecularstructures of PSTM-3T polymer were modeled at differentpH conditionswith consideration of tautomerization and dis-sociation Geometries of all the considered model molecules(Figure 1) in this study were fully optimized by using densityfunctional theory (DFT)with Beckersquos three-parameter hybridexchange function [14] and the Lee-Yang-Parr correlationfunction (B3LYP) [15] and with the 6-31G(d p) basis set [16]method in Gaussian 03 package [17] Vibrational frequenciesand absolute IR intensities of optimized structures were

Sindash(CH2)3ndashNHndashCndashNHndash(CH2)3ndashSiO15n=

SO15

Scheme 1 Representation of molecular structure of PSTM-3Tpolymer

10120583m

Figure 1 SEM image of synthesized PSTM-3T polymer

investigated with 6-311G(d p) level All the convergent preci-sions were the system default values and the all calculationswere carried out on the standard lab-level workstation withAMD Opteron 285 dual core CPU Data visualization wascarried out using GaussView 30 [18]

3 Results and Discussion

31 Characterization of PSTM-3T Polymer The details ofchemical composition of PSTM-3T by EDS analysis are givenin Table 1 The major elements of the sample verified thePSTM-3TpolymerThe elemental analysis showed the similarresults with theoretically calculated contents of synthesizedtitle polymer as formula of C

7H14N2O3SSi2(Scheme 1) The

SEM was performed on an irregular and porous surface(Figure 1) which indicates high surface areas of 490m2g with353 cm3g total pore volume

The functional groups were identified using FT-IR exper-iment and the spectrum is shown in Figure 2 In Figure 2the observable IR signals for PSTM-3T were 58057 and69241 cmminus1 forC-S 156041 337350 and 338893 cmminus1 forN-H and 163178 cmminus1 for C-NThe IR signals were similar withthe group frequencies [19] In this study the model of PSTM-3T (Figure 3(a)) was investigated using the density functionalB3LYP method with 6-311G(d p) basis set (Table 2) All thevalues have relative deviation less than 53 (Table 2) and thetheoretical values are in good agreement with experimentalvalues the same as previous other reports [20]

32 Sorption of Heavy Metal Ions The solution pH is one ofthemost important factors for heavymetal sorption from theaqueous solution Sorption of copper and chromate ions wasrevealed at various pH conditions and the sorption strengthsare shown in Figure 4 The fraction of sorption of copperion as determined by the removal of copper ion percentage




C 3694 3433 3742N 1423 971 773O 2316 2267 2166Si 1840 1300 2175S 710 1051 1117Cu 052Cr 026



Exp Cal

CS 58057 56264 minus30969241 72857 +522

NH156041 154281 minus113337350 355203 +529338893 356054 +506

CN 163178 155677 minus401


119865 =(1198600minus 119860119905)

1198600

(1)

where 1198600and 119860



119876119890=(1198620minus 119862119890) 119881

119898 (2)







5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

20658

337350

(ndashN

H)

338893

(ndashN

H)

163178

(ndashCN

)156041

(ndashN

H)

69241

(ndashCS

)58057

(ndashCS

)


H

HH

HH

HH

H H H HH

HHHHC

C CC

CC

C

S

N N

(a)

HH

HH

H

HH

HH

HHH

H

H

H

C C CC C

CC

S

NN

(b)

HH

H

H

H

HH H

HH

HH

H

HH

CC

CCC

S

NN

(c)






30

25

20

15

10

5

00 50 100 150 200 250 300

pH2

pH3

pH4

pH5

Frac

tion

of ad

sorp

tion

F(

)

Time (min)

Qe = 7mggat pH = 5

(a)

40

35

30

25

20

15

10

5

02 4 6 8 10

Am

ount

at eq

uilib

rium

Qe

(mg

g)

pH


(b)


Abso

rban

ce

5001000150020002500300035004000

Wavenumbers (1cm)

206190

330020

(ndashN

H)

155848

(ndashN

H)

163371

(ndashCN

)

66544

(ndashCS

)55357

(ndashCS

)

(a)

5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

341400

(ndashN

H)

156041

(ndashN

H)

163564

(ndashCN

)

60372

(ndashCS

)49185

(ndashCS

)(b)



2 HD and D




SH

pH2 pH5

minusH+



=

S Sminus

ndashndash






CS 55357 58238 +52066544 69299 +414

NH 155848 152808 minus195330020 357594 +836

Inter 206190CN 163371 152808 minus647



Exp Cal

CS 49185 51748 +52160372 60319 minus009

NH 156041 148339 minus494341400 354976 +398

SH 270003CN 163564 168672 +312



4 Conclusion




Acknowledgments


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






C 3694 3433 3742N 1423 971 773O 2316 2267 2166Si 1840 1300 2175S 710 1051 1117Cu 052Cr 026



Exp Cal

CS 58057 56264 minus30969241 72857 +522

NH156041 154281 minus113337350 355203 +529338893 356054 +506

CN 163178 155677 minus401


119865 =(1198600minus 119860119905)

1198600

(1)

where 1198600and 119860



119876119890=(1198620minus 119862119890) 119881

119898 (2)







5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

20658

337350

(ndashN

H)

338893

(ndashN

H)

163178

(ndashCN

)156041

(ndashN

H)

69241

(ndashCS

)58057

(ndashCS

)


H

HH

HH

HH

H H H HH

HHHHC

C CC

CC

C

S

N N

(a)

HH

HH

H

HH

HH

HHH

H

H

H

C C CC C

CC

S

NN

(b)

HH

H

H

H

HH H

HH

HH

H

HH

CC

CCC

S

NN

(c)






30

25

20

15

10

5

00 50 100 150 200 250 300

pH2

pH3

pH4

pH5

Frac

tion

of ad

sorp

tion

F(

)

Time (min)

Qe = 7mggat pH = 5

(a)

40

35

30

25

20

15

10

5

02 4 6 8 10

Am

ount

at eq

uilib

rium

Qe

(mg

g)

pH


(b)


Abso

rban

ce

5001000150020002500300035004000

Wavenumbers (1cm)

206190

330020

(ndashN

H)

155848

(ndashN

H)

163371

(ndashCN

)

66544

(ndashCS

)55357

(ndashCS

)

(a)

5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

341400

(ndashN

H)

156041

(ndashN

H)

163564

(ndashCN

)

60372

(ndashCS

)49185

(ndashCS

)(b)



2 HD and D




SH

pH2 pH5

minusH+



=

S Sminus

ndashndash






CS 55357 58238 +52066544 69299 +414

NH 155848 152808 minus195330020 357594 +836

Inter 206190CN 163371 152808 minus647



Exp Cal

CS 49185 51748 +52160372 60319 minus009

NH 156041 148339 minus494341400 354976 +398

SH 270003CN 163564 168672 +312



4 Conclusion




Acknowledgments


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




30

25

20

15

10

5

00 50 100 150 200 250 300

pH2

pH3

pH4

pH5

Frac

tion

of ad

sorp

tion

F(

)

Time (min)

Qe = 7mggat pH = 5

(a)

40

35

30

25

20

15

10

5

02 4 6 8 10

Am

ount

at eq

uilib

rium

Qe

(mg

g)

pH


(b)


Abso

rban

ce

5001000150020002500300035004000

Wavenumbers (1cm)

206190

330020

(ndashN

H)

155848

(ndashN

H)

163371

(ndashCN

)

66544

(ndashCS

)55357

(ndashCS

)

(a)

5001000150020002500300035004000

Abso

rban

ce

Wavenumbers (1cm)

341400

(ndashN

H)

156041

(ndashN

H)

163564

(ndashCN

)

60372

(ndashCS

)49185

(ndashCS

)(b)



2 HD and D




SH

pH2 pH5

minusH+



=

S Sminus

ndashndash






CS 55357 58238 +52066544 69299 +414

NH 155848 152808 minus195330020 357594 +836

Inter 206190CN 163371 152808 minus647



Exp Cal

CS 49185 51748 +52160372 60319 minus009

NH 156041 148339 minus494341400 354976 +398

SH 270003CN 163564 168672 +312



4 Conclusion




Acknowledgments


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






CS 55357 58238 +52066544 69299 +414

NH 155848 152808 minus195330020 357594 +836

Inter 206190CN 163371 152808 minus647



Exp Cal

CS 49185 51748 +52160372 60319 minus009

NH 156041 148339 minus494341400 354976 +398

SH 270003CN 163564 168672 +312



4 Conclusion




Acknowledgments


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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