Research Article Defluoridation with Locally Produced Thai

Research ArticleDefluoridation with Locally Produced Thai Bone Char

Yothin Mutchimadilok1 Sunisa Smittakorn1

Surat Mongkolnchai-arunya2 and Deanna Durnford3

1 Department of Civil Engineering Thammasat University PathumThani 12120 Thailand2Dental Health Division Department of Health Ministry of Public Health Nonthaburi 11000 Thailand3Department of Civil Engineering Colorado State University Fort Collins CO 80523 USA

Correspondence should be addressed to Sunisa Smittakorn ssunisaengrtuacth

Received 27 June 2014 Accepted 3 August 2014 Published 19 August 2014

Academic Editor Jesus Simal-Gandara

Copyright copy 2014 Yothin Mutchimadilok 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 fluoride sorption ability of a locally available bone char is quantified Both a synthetic solution and natural groundwater samplesfrom several sites are studied and compared to Indian bone char which is widely accepted and used successfully in India andelsewhere The Freundlich and Langmuir sorption isotherms were used to quantify sorption properties Results show that theThaibone char is as effective as the Indian bone char for removing fluoride from contaminated water despite the more rigid physicaland social constraints found in ruralThailand Sorption studies with fluoride-contaminated natural groundwater samples also showthat chlorides nitrates and sulfates had little effect on the removal of fluoride by the homemade bone char

1 Introduction

Fluoride contamination of groundwater is a common envi-ronmental problem worldwideThe allowable drinking waterstandard for fluoride is 15mg Lminus1 [1] Concentrations offluoride higher than this level affect both teeth and boneresulting in dental or skeletal fluorosis In rural Thailandfluoride concentrations in groundwater range from 1 to20mg Lminus1 and dental fluorosis has been recorded since 1960[2] Studies have also documented liver and kidney damage[3] and a bone cancer called osteosarcoma found in youngboys exposed to high levels of fluoride [4] Continuous intakeof fluoride may also cause damage to the nervous system [5]

Fluoride removal at point of use is still an ongoingresearch area since themajor water source inmost rural areasaround the world is groundwater Rural areas use ground-water for drinking and household use Centralized methodssuch as the village-centered reverse osmosis systems installedin about 1250 villages inThailand between 2004 and 2008 forfluoride removal are costly require high maintenance andare simply not available to many rural areas

Effective fluoride removalmethods such as reverse osmo-sis [6 7] and membrane technology [8ndash10] are applied in

many countries however the high installation and mainte-nance costs of these methods generally preclude their use inpoor countries Low cost fluoride removal technologies suchas coagulation [11] and adsorption [12] are more acceptablein developing countries Adsorption is a very popularmethodbecause of its simplicity in preparation operation andmaintenance Recently many attempts have beenmade to usewaste or low cost materials as the absorbent The materialsstudied include bauxite [13] montmorillonite [14] activatedwater treatment sludge [15] waste mud [16] red mud [17]granular ceramic [18] hydrous iron (III)-tin (IV)mixed oxide[19] and schwertmannite [20]

Bone charcoal or bone char has been successfully usedfor fluoride removal in India and Tanzania [24 25] Theeffectiveness of bone char as an adsorbent has been studiedusing batch experiments with synthetic fluoride solutionsunder different conditions for example variable pH tem-perature chemical and thermal activation adsorbent dosageinitial fluoride concentration and coexisting anions [26]Activated alumina sorbed less fluoride in high pH (gt8) con-ditions [27] Fluoride adsorption by granular ceramic [18]activated alumina [27] granular ferric hydroxide [26] andschwertmannite [20] was found to decrease in the presence

Hindawi Publishing CorporationAdvances in Environmental ChemistryVolume 2014 Article ID 483609 9 pageshttpdxdoiorg1011552014483609

2 Advances in Environmental Chemistry

of phosphate Competing ions were found to have no effecton fluoride adsorption by other absorbents such as hydrousiron (III)-tin (IV) mixed oxide [19] polymer composites[28] and disposed earthenware [29] However sulfate andphosphate ions were found to compete with fluoride sorptionon materials with iron and aluminum bases [13] Chlorideand sulfate interfered with fluoride removal by mixed-phasenano iron oxides [30] All these experiments on the influenceof other ions on sorption were done with synthetic fluoridesolutions mixed with only single ion Actual groundwaterhowever contains multiple ions The interactions of theseions on fluoride sorption of bone char have not been welltested

There is a clear need inThailand to develop a point-of-usedefluoridator that will be successful in rural areas ofThailandthat are experiencing high fluoride levels In a previous paperby the authors [31] a simple method of producing bone charfor a point-of-use defluoridator in rural areas of Thailand isdescribed The boiled cow bone from a gelatin productionfactory is the raw material The homemade furnace consistsof a 20-liter recycled steel tank The boiled bone is placedin the middle of the tank surrounded by rice husks Afterclosing the lid of the tank the burning process takes about 8hours at which time the temperature reaches 500∘C to 600∘CThe bone char is left in the container to cool down for 24hours The advantages of the method compared to previousmethods include elimination of the need for the user tohandle fresh bone the use of small homemade furnacesno offensive smell during the burning process no need forchemical additives during the process and no requirementfor crushing or sieving of the bone at the local level Thesedifferences address societal and physical constraints in ruralareas of Thailand

The purpose of this paper is to report the results of a studyof the adsorption properties of theThai homemade bone charreferred to as THAI BC in this paper The kinetics of theadsorption process are investigated The effect of the size ofthe homemade bone char is studied to insure that the simpleproduction of homemade bone char will yield reasonableresults for fluoride removal without further crushing of thebone Results are compared to those of Indian bone char(IND BC) which is widely accepted and effectively used asan adsorbent in the removal of fluoride in India and otherareas worldwide The sorption ability of the Thai homemadebone char was also evaluated using natural groundwaterNatural groundwater contains multiple component ions Theresearch presented here addresses the influence of these otherions on fluoride removal In addition fluoride-contaminatedgroundwater samples were collected from several sites inChachengsao Phetchaburi and Nakorn Pathom provinces ofThailand

2 Materials and Methods

Boiled cow bone courtesy of the Thai Bone Industry inPathumThani province Thailand was the raw material Twoadvantages of using boiled bone instead of fresh bone are thehygienic handling of the bone and the lack of an offensive

odor during the charring process A homemade furnace ismade from a 200-litre steel container It should be noted thatthe size of the steel container has been increased from theprevious work so that more bone char can be produced Ricehusks are used as fuel Dried rice leaves were initially testedhowever the heat generated from the leaves was less than500∘C resulting in a poorer quality of bone char Rice husksare well known as an alternative renewable fuel A stainlesssteel pot is filled with about 7 kg of the boiled bone and placedon top of the rice husk The lid is closed and rice husks areadded until the pot is covered The fire is lit and rice husksfill the whole container Typically heat is applied for about 8hours with bone char being left to cool for about 24 hoursbefore it is removed About 5 kg of bone char is left fromthe process In this paper this bone char is referred to asTHAI BC The length of the bone char produced is about 1to 3 cm As discussed by Smittakorn et al [31] for acceptancein Thailand the production of the homemade bone char hasto be simple and to require no added chemicals no sievingor crushing during the process readily available local rawmaterials and no need for small households to handle thefresh bone

A series of batch experiments were conducted to assessthe effect of bone char size on the fluoride removal abilityThe bone char was crushed with a mortar and pestle andthen sieved into four different sizes which were less than0841mm 0841ndash118mm 119ndash237mm and 238ndash474mmIn these tests 200mL of a synthetic fluoride aqueous solutionwith a concentration of 39mgL was mixed with 10 g of thehomemade bone char in a plastic bottle and then shaken in awater bath at room temperature Samples were collected andanalyzed at 2 4 6 8 10 12 16 20 and 24 hours Sorptionkinetics and isotherms for each size of bone char were thenanalyzed

The fluoride sorption capacity of the Thai bone char(THAI BC) was then compared to that of Indian bone charIndian bone char (IND BC) was set as a benchmark since itis successfully used in India and elsewhere For these testssix groundwater samples were collected from wells at sites inChachengsao Phetchaburi and Nakorn Pathom provinces ofThailand The groundwater was stored in plastic containersand kept refrigerated prior to the sorption tests The fluorideconcentrations of the groundwater samples (designated asGW1 to GW6) ranged from 3 to 19mgL while the syntheticfluoride concentrationwas again 39mgL Procedures for thebatch experiments are as described above

The final tests presented in this paper investigate the effectof multiple ions on the sorption ability of bone charTheThaiand Indian bone chars were compared for sorption capacityusing a synthetic solution and a second set of groundwatersamples from six locations in Chachengsao Phetchaburi andNakorn Pathom provinces of Thailand These were collectedfrom different wells from the isotherm experiment and aredesignated as Sites 1 through 6 Samples were taken at thetime to equilibrium assumed to be 12 hours Again batch testsprocedures are described above

Fluoride and other ion concentrations were measuredusing the ion analyzer EA 940 at the analytical labora-tory of the Dental Health Division Department of Health

Advances in Environmental Chemistry 3

Table 1 Constants and goodness of fit for size ranges of Thai BC using linear first order and second order kinetic equations

Size of BC(mm)

119902119890

(mgg)(experiment)

Zero order equation First order equation Second order equation1198960

(hminus1) 119902119890

(mgg) 1198772

1198961

(hminus1) 119902119890

(mgg) 1198772

1198962

(gsdotmgminus1sdothminus1) 119902119890

(mgg) 1198772

238ndash474 0067 00025 0048 0875 0143 0070 0967 1235 0094 0959119ndash237 0069 00023 0041 0783 0187 0070 0942 2154 0086 09650841ndash118 0062 00019 0034 0700 0127 0042 0954 2833 0074 0987lt0841 0073 00023 0048 0880 0105 0061 0985 1421 0092 0988

119875 value 152 lowast 10minus3 028 929 lowast 10

minus3

0102030405060708090

100

0 5 10 15 20 25 30

Adso

rptio

n (

)

Time (hour)

238ndash474 mm 119ndash237 mm

0841ndash118 mmLess than 0841 mm

Figure 1 Adsorption percentage at different times for each range ofbone char size

Ministry of Public Health Nonthaburi Thailand The SaiOral Health foundation in Hyderabad India (httpwwwsaioralhealthfoundationorg) supplied the Indian bone char(IND BC) used throughout this work

3 Results and Discussions

31 Contact Time or Time to Equilibrium as a Function of BoneChar Size One criterion for the Thai bone char is that thelocal user need not crush the bone To determine if the sizeof the Thai bone char produced by the homemade furnaceaffects sorption the bone char was crushed and sieved intofour size ranges Batch experiments were performed foreach size range of bone char A synthetic solution with aconcentration of 39mgL was used in these tests

The relationship between contact time and the adsorptionpercentage is shown in Figure 1The percent sorbed increasedwith time for the first 12 hours after which data reached anasymptote at about 80 (Figure 1) Thus it can be assumedthat the contact time or time to equilibrium for all size rangesof the homemade bone char THAI BC is 12 hours Time toequilibrium for other sorbates has been found to range fromone hour to 72 hours [12]

The smallest size of bone char had a more rapid adsorp-tion rate at earlier time This result agrees with Mjengeraand Mkongo [25] who concluded that fine particles wouldremove fluoride faster because there is more available surfacearea However clogging will likely occurmore easily with fine

particles and handling of these finer particles will complicateproduction of the bone char

32 The Effect of Thai Bone Char Sizes on the SorptionCapacity in the Synthetic Fluoride Solution

321 Adsorption Kinetics To evaluate the efficacy of thehomemade bone char another set of batch experimentswas performed The procedure was similar to those earlierexperiments in that 200mL of a synthetic fluoride solutionwith the concentration of 39mgL was shaken with 10 g ofhomemade bone char Samples were collected until 12 hoursThe data were fit to pseudo zero first and second orderadsorptionmodels to quantify the adsorption kinetics ofThaibone char to the synthetic fluoride solution

The pseudo zero order kinetic equation is given by

119902119890

minus 119902119905

= 119902119890

minus 1198960

119905 (1)

where 119902119890

and 119902119905

are the mass of sorbed fluoride per unitmass of the adsorbent (mg gminus1) at equilibrium and at any time119905 (h) respectivelyThe rate constant 119896

0

was assumed constantcomputed from the best-fit slope of a linear plot of (119902

119890

minus 119902119905

)

versus timeThe pseudo first order kinetic equation of Lagergren [32]

is given by

log (119902119890

minus 119902119905

) = log 119902119890

minus

1198961

2303

119905 (2)

The rate constant 1198961

is determined from the slope of thelinear relationship described by (2)

A pseudo second order kinetic equation [33] is given as

119905

119902119905

=

1

1198962

1199022

119890

+

119905

119902119890

(3)

where the rate constant is 1198962

A linear relationship between(119905119902119905

) and time was constructed to determine the rate con-stant for this equation

The constants determined for (1) (2) and (3) are shownin Table 1 for each size range of Thai BC investigated alongwith correlation coefficients The correlation coefficients 1198772for the pseudo first order and second order equations werefound to be closer to 1 than those obtained from the zeroorder equation Comparing the amount of fluoride sorbedat equilibrium per unit mass of bone char (119902

119890

) from theexperimental results with the best fit for 119902

119890

using the equa-tions the 119875 value from zero order and second order kinetic


equations was less than 005 This indicates that the values of119902119890

using these two equations were significantly different fromthe experimental values The 119875 values from the first orderkinetic equation by Lagergren [32] were greater than 005meaning that equilibrium concentrations 119902

119890

predicted bythis equation were good fits to the experimental values Sinceboth the 1198772 and 119875 values are high for the Lagergren equationit can be concluded that this first order kinetic model bestdescribes the rate of adsorption of fluoride onto Thai bonechar

322 The Sorption Isotherm Freundlich [34] presented asorption isotherm that is widely used for fitting results ofsorption experiments The Freundlich equation is given by

119902119890

= 119870119889

119862119890

1119899

(4)

where 119902119890

is the mass of the solute adsorbed at equilibriumper unit mass of adsorbent (mg gminus1) 119862

119890

is the fluorideconcentration at equilibrium (mg Lminus1) 119870

119889

is a constantwhich is a measure of the adsorption capacity and 1119899 is aconstant which is a measure of the adsorption intensity TheFreundlich sorption isotherm is linearized as

log (119902119890

) = log (119870119889

) +

1

119899

log (119862119890

) (5)

A limitation of the Freundlich sorption isotherm is that thereis no maximum limit to the sorbed solute

The Langmuir sorption isotherm [35] is also commonlyused in sorption studies The Langmuir sorption isotherm isgiven by

119902119890

=

119902119898

119870119860

119862119890

1 + 119870119860

119862119890

(6)

where 119862119890

is the fluoride concentration at equilibrium(mg Lminus1) 119902

119890

is the mass of sorbed fluoride per unit mass ofbone char at equilibrium (mg gminus1) 119902

119898

is the mass of sorbedfluoride per unitmass of bone char at saturation (mg gminus1) and119870119860

is an isotherm constant To evaluate parameters from theLangmuir sorption isotherm (6) is rearranged resulting in alinear relationship between 119862

119890

and (119862119890

119902119890

)

119862119890

119902119890

=

119862119890

119902119898

+

1

119870119860

119902119898

(7)

Results of fitting the data from the batch tests to theFreundlich and Langmuir sorption isotherms are shown inTable 2

A low 1119899 in the Freundlich equation implies that thereis a strong bond between the adsorbent and the adsorbateIn this case the values of 1119899 for all sizes of bone char weresimilar with an average of 069 Similar values of 119870

119889

meanthat the sorption capacities for different sizes of bone charare similar This is the case for all size except for the smallestsize (less than 08mm) where the greater surface area likelyaffects the isotherm as mentioned previously

Other researchers have computed Freundlich parametersfor bone char of various sizes from 05 to 129mm Results

Table 2 Freundlich and Langmuir sorption isotherms parametersfor different size ranges of the Thai BC using synthetic solution(39mgL)

Range of BCsize (mm)

Freundlich isotherm Langmuir isotherm119870119889

1119899 1198772

119902119890

119870119860

1198772

238ndash474 0053 0728 0901 0279 0241 0973119ndash237 0059 0792 0940 0597 0109 09460841ndash118 0050 0610 0934 0214 0309 0984lt0841 0136 0633 0781 0243 1206 0928

are summarized in Table 3 and compared to parameters inthis study Differences can be explained in part because theinitial fluoride concentration in the batch tests in this paperhad a concentration of 39mgL whereas the range was largerin the other papers from 1 to 20mgL In additionThai bonechar was manufactured from a homemade furnace whilebone char from other works was commercially producedThehomemade furnace would produce a less consistent productThis could be another reason for the lower sorption capacityfound for the Thai bone char

33 Comparison of Sorption Isotherms for Thai and IndianBone Char for Natural Groundwater Samples Groundwatersamples were collected fromwells at six sites in ChachengsaoPhetchaburi and Nakorn Pathom provinces of ThailandThese water samples will be used to compare sorptionisotherms for the Thai bone char with those for Indian bonechar Indian bone char does not address all of the societalissues required for small scale defluoridators in Thailandbut it is widely accepted and successfully used in manyareas worldwide Because of its wide acceptance it is usedhere as a benchmark The Indian bone char was suppliedby the Sai Oral Health foundation in Hyderabad India(httpwwwsaioralhealthfoundationorg)

It was shown in the previous section that the size ofbone char does not affect the adsorption capacity ThereforeThai bone char produced without crushing will be tested inthis section The fluoride concentrations in the groundwatersampled designated as water samples GW1ndashGW6 in thispaper range from 3 to 19mgL The synthetic fluoride con-centration is again 39mgL TheThai and Indian bone charsare compared using the Freundlich and Langmuir sorptionisotherms (Tables 4 and 5)

From Table 4 the 119875 values for 119870119889

and 1119899 were greaterthan 005 which indicates that there was no significantdifference in means between Thai and Indian bone char foreither parameter The Langmuir sorption isotherm (Table 5)shows that the equilibrium capacities 119902

119890

and values of119870119860

fortheThai and Indian bone char were similar with 119875 values for119902119890

and 119870119860

greater than 005 From both sorption isothermsthe 1198772 values are quite comparable although the 1198772 from theFreundlich isotherms showed a slightly better fit than thosefrom the Langmuir sorption isotherm From these results itis concluded that Thai bone char is as effective in removingfluoride as the widely accepted Indian bone char and thateither the Freundlich or the Langmuir sorption isotherm can


Table 3 Comparison of fitted Freundlich sorption isotherm parameters for different sizes of bone char found in this study with parametersfrom other publications

Bone char size (mm) 119870119889

1119899 pH Type of bone char Reference238ndash474 0053 0728 8 Charred by homemade furnace This work119ndash237 0059 0792 8 Charred by homemade furnace This work0841ndash118 0050 0610 8 Charred by homemade furnace This worklt0841 0136 0633 8 Charred by homemade furnace This work079 2710 0284 7 Commercial BC Medellin-Castillo et al 2007 [21]079 0870 0339 10 Commercial BC Medellin-Castillo et al 2007 [21]05ndash10 0549 0510 NA Charred by electric furnace Kawasaki et al 2009 [22]065 2840 0328 7 Commercial BC Leyva-Ramos et al 2010 [23]079 2720 0289 7 Commercial BC Leyva-Ramos et al 2010 [23]129 1950 0435 7 Commercial BC Leyva-Ramos et al 2010 [23]lowastA synthetic solution was used in these testsNA pH condition was not reported

Table 4 Parameters for the Freundlich sorption isotherm comparingThai and Indian bone char

Sample 119870119889

1119899 1198772

THAI BC IND BC THAI BC IND BC THAI BC IND BCGW1 0053 0064 0634 0664 0965 0947GW2 0057 0079 0634 0792 0953 0932GW3 0060 0051 0654 0812 0943 0987GW4 0049 0069 0936 0679 0925 0932GW5 0056 0066 0705 0499 0862 0805GW6 0072 0099 0757 0766 0987 0957Syn 0063 0081 0595 0671 0941 0950119875 value 0063 0940

be used to describe the process This finding agrees with Abeet al [36] and Medellin-Castillo et al [21]

34 The Effect of Multiple Ions on the Sorption Capacity Thaiand Indian bone char sorption capacities are compared inthis section to determine the effects of multiple ions on thesorption capacity The tests again used the synthetic solution(initial concentration of 39mg Lminus1) and an additional set ofgroundwater samples taken from wells in six locations inChachengsao Phetchaburi and Nakorn Pathom provincesof Thailand The chemical constituencies of the groundwatersamples are shown in Table 6 Samples were taken for analysisat a time to equilibrium assumed to be 12 hours Figure 2shows the amount of fluoride sorbed per unit mass compar-ing Thai and Indian bone char when the solution containsdifferent concentrations of (a) chloride (b) nitrate (c) sulfateand (d) fluoride

Table 7 shows Pearson correlation coefficients betweenfluoride and both the Thai and Indian bone chars thatare close to one (0942 and 0831 resp) indicating a highpositive linear relationship between those two parametersThus the amount of fluoride sorbed onto bone char tendsto increase with the increasing initial fluoride concentration(see Figure 2(d)) This agrees with results by Eskandarpouret al [20] On the other hand the correlation coefficientsbetween chloride nitrate and sulfate to eitherThai or Indian

bone char approach zero (except for the case of sulfate andThai bone char) implying that there is less of the relationshipor an uncorrelated relationship between ion concentrationsand the sorbed fluoride per weight of bone char Even thoughthe chloride and nitrate contain mono anions as well asfluoride the adsorption mechanisms of chloride and nitrateare totally different than fluorideWhile fluoride adsorbs withstrong bonds by active sites at the inner Helmholtz planechloride and nitrate adsorb with weaker bonds at active siteson the outer Helmholtz planeThe presence of sulfate showedno obvious effect on fluoride adsorption The adsorptionmechanism of sulfate is only partially inner Helmholtz planebut it might interfere with the fluoride adsorption slightly[20]

Abe et al [36] report that the amount of sorbed fluorideincreased with increased concentration of chloride in thesolutionThe difference between Abe et al [36] and this studyis type of fluoride-contaminated solution In Abe et alrsquos studysynthetic fluoride solution with only sodium chloride addedinto the fluoride solution while in this study multiple ionspresented in the actual groundwater Other ions might havebeen the contribution to such different result

The concentrations of chloride nitrate sulfate and phos-phate were also evaluated after the batch test There was nosignificant change in the concentration of any ions exceptfor phosphate Chloride nitrate and sulfate do not compete


Table 5 Parameters for the Langmuir sorption isotherm comparingThai and Indian bone char

Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030

000 2020 3240 5010 5950 6890 12700Chloride concentration (mgL)

Sorb

edFminus

per w

t of

BC

(mg

g)

(a) Chloride the water samples (from left) are the synthetic solution andsites 1 2 3 5 4 and 6 are in Table 1 shown in increasing concentrations

000

005

010

015

020

025

030

000 077 095 120 140 220 330Nitrate concentration (mgL)

Sorb

edFminus

per w

t of

BC

(mg

g)

(b) Nitrate the water samples (from left) are the synthetic solution and sites2 1 4 5 3 and 6 are in Table 1 shown in increasing concentrations

000

005

010

015

020

025

030

000 363 2260 2580 18400 19400 21500Sulfate concentration (mgL)

Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC

(c) Sulfate the water samples (from left) are the synthetic solution andsites 6 1 2 4 5 and 3 are in Table 1 shown in increasing concentration

000

005

010

015

020

025

030

390 1057 1093 1360 1380 1627 1877Fluoride concentration (mgL)

Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC

(d) Fluoride the water samples (from left) are the synthetic solution andsites 4 6 2 5 1 and 3 are in Table 1 shown in increasing concentration

Figure 2 Comparisons of the mass of fluoride sorbed per unit mass of Thai and Indian bone char with the increasing concentrations of (a)chloride (b) nitrate (c) sulfate and (d) fluoride in the groundwater samples

with the fluoride ion on bone char Prior to the batch testthe concentration of phosphate was less than 001mgLwhile the final concentration of phosphate was 08mgLTheincreasing concentration of phosphate associated with thefluoride removal by bone char is similar to two previousworks [22 37] He et al [37] note that tricalcium phosphateis partially broken off in water which can occur in threedifferent possible pH states acidic neutral and alkaline

These are shown in (8) (9) and (10) respectively Considerthe following

acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)


Table 6 Ion concentrations in the groundwater samples

Number Concentration (mgL)Fminus Clminus NO

3

minus SO4

2minus PO4

3minus

Site 1 1627 2020 095 2260 lt01Site 2 1360 3240 077 2580 lt01Site 3 1877 5010 220 21500 043Site 4 1057 6890 120 18400 lt01Site 5 1380 5950 140 19400 lt01Site 6 1093 12700 330 363 lt01Syn 39 mdash mdash mdash mdash

Table 7 The Pearson correlation coefficient between sorbed fluo-ride per mass of bone char and each ion

Ion Thai bone char Indian bone charChloride minus0168 minus0264Nitrate 0129 0105Sulfate 0474 0183Fluoride 0942 0831

neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)

From all three possible reactions the phosphate ionappears as a product of the reaction From (10) after thereaction the H+ ion is released at an alkaline conditionresulting in the decreasing pH The final pH of groundwaterin our batch tests was 82 which was slightly more acidicwhen compared to the initial pH of solutions which was 83There was relatively no change in the pH smell and color ofthe treated groundwater

4 Conclusions

Thegroundwater inmany rural areas ofThailand has fluorideconcentrations that are as high as 20mgL much higher thanthe drinking water standard of 15mgL However attemptsto provide centralized treatment systems to remove thefluoride have failed Small point-of-use defluoridators facelimitations that are unique to Thailand This study evaluatedthe sorption properties of a bone char produced using amethod introduced in an earlier paper to address a numberof societal and physical constraints that the authors foundin rural Thailand These constraints included elimination ofthe need for the small household user to handle fresh bone

and the use of small homemade furnaces and elimination ofthe need for chemical additives during the process requiringreadily available local materials and no crushing or sievingof the bone at the local level Boiled bone as raw materialfor the defluoridator is available through the bone factory ineach province However the government should provide theinformation such as the location of such factory in the area oreven set up a distribution center of the boiled bone

This paper presents the results of batch tests whichcompare the sorption properties of the homemadeThai bonechar with Indian bone char Indian bone char was usedas a benchmark because it is used effectively in India andelsewhere and is well accepted as an effective sorbent forfluoride Our results showed that for both synthetic fluoridesolution and natural fluoride-contaminated groundwater theThai bone char was as effective as the Indian bone char Wealso found that there was no advantage or need to furthercrush the bone provided by the gelatin factory The paperpresents coefficients for common isotherms for Thai bonechar sorption and we found that coexisting ions such aschloride nitrate and sulfate have little effect on the sorptionproperties of the Thai bone char The sorption capability ofhomemade bone char is less than other expensive commercialsorbents However even though the coefficients derived fromsorption isotherms forThai BC were less than those found inothersrsquo work the defluoridator meets the goal of a sustainablehousehold device that removes fluoride at low levels Inthis application the Thai homemade bone char shows highpotential to remove fluoride in remote areas of Thailandwhere groundwater is essential for household consumptionLastly it is possible to regenerate the bone char using theburning process Further researches can be done to evaluatethe optimum conditions to regenerate the exhausted bonechar such as the temperature and the duration of the heatingprocess It is also necessary to consider the longevity and thefluoride removal effectiveness of the regenerated bone char

Notations

119862 Constant related to thickness of the boundary layer(mg gminus1)

119862119861

Desired concentration of solute (mg Lminus1)119862119890

Fluoride concentration at equilibrium (mg Lminus1)1198620

Initial concentration of fluoride (mg Lminus1)119862119905

Fluoride concentration at any time (mg Lminus1)1198960

Rate constant of pseudo zero order equation (hminus1)1198961

Rate constant of pseudo first order equation (hminus1)1198962

Rate constant of pseudo second order equation(gmgminus1 hminus1)

119870 Adsorption rate constant (mg Lminus1minminus1)119870119860

Langmuir isotherm constant119870119889

Constant which is a measure of the adsorptioncapacity

119896119901

Intraparticle diffusion rate constant (mg gminus1 hminus12)119899 Constant related to the adsorption capacity


119902 Weight of sorbed fluoride at any time per unit weightof bone char (mg gminus1)

119902119890

Weight of sorbed fluoride at equilibrium per unitweight of bone char (mg gminus1)

119902119898

Weight of sorbed fluoride at saturation per unit weightof bone char (mg gminus1)

119902119905

Weight of sorbed fluoride at any time per unit weightof bone char (mg gminus1)

119905 Time (h)

Conflict of Interests

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

Acknowledgments

The authors gratefully acknowledge the Sai Oral Healthfoundation in Hyderabad India (httpwwwsaioralhealth-foundationorg) for providing the Indian bone char and theThai Bone Industry for providing boiled bone used in thisstudy Comments from Dr Warounsak LiamLeam Facultyof Engineering Thammasat University are gratefully appre-ciated This research is in part funded by the Faculty ofEngineering Thammasat University

References

[1] World Health Organization Guidelines for Drinking-waterQuality Volume 1 Recommendation WHO Geneva Switzer-land 3rd edition 2006

[2] E C Leatherwood G W Burnett R Chandravejjsmarn andP Sirikaya ldquoDental caries and dental fluorosis inThailandrdquoTheAmerican journal of public health and the nationrdquos health vol 55no 11 pp 1792ndash1799 1965

[3] X Xiong J Liu W He et al ldquoDose-effect relationship betweendrinking water fluoride levels and damage to liver and kidneyfunctions in childrenrdquo Environmental Research vol 103 no 1pp 112ndash116 2007

[4] E B Bassin D Wypij R B Davis and M A Mittleman ldquoAge-specific fluoride exposure in drinking water and osteosarcomardquoCancer Causes and Control vol 17 no 4 pp 421ndash428 2006

[5] L Valdez-Jimenez C Soria Fregozo M L Miranda BeltranO Gutierrez Coronado and M I Perez Vega ldquoEffects of thefluoride on the central nervous systemrdquo Neurologia vol 26 no5 pp 297ndash300 2011

[6] R W Schneiter and E J Middlebrooks ldquoArsenic and fluorideremoval from groundwater by reverse osmosisrdquo EnvironmentInternational vol 9 no 4 pp 289ndash291 1983

[7] L A RichardsM Vuachere andA I Schafer ldquoImpact of pH onthe removal of fluoride nitrate and boron by nanofiltrationreverse osmosisrdquo Desalination vol 261 no 3 pp 331ndash337 2010

[8] D Hou J Wang C Zhao B Wang Z Luan and X SunldquoFluoride removal from brackish groundwater by direct contactmembrane distillationrdquo Journal of Environmental Sciences vol22 no 12 pp 1860ndash1867 2010

[9] R Kettunen and P Keskitalo ldquoCombination of membranetechnology and limestone filtration to control drinking waterqualityrdquo Desalination vol 131 no 1ndash3 pp 271ndash283 2000

[10] H Lounici D Belhocine H Grib M Drouiche A Pauss andN Mameri ldquoFluoride removal with electro-activated aluminardquoDesalination vol 161 no 3 pp 287ndash293 2004

[11] W X Gong J H Qu R P Liu and H C Lan ldquoEffect of alu-minum fluoride complexation on fluoride removal by coagula-tionrdquo Colloids and Surfaces A Physicochemical and EngineeringAspects vol 395 pp 88ndash93 2012

[12] A Bhatnagar E Kumar and M Sillanpaa ldquoFluoride removalfrom water by adsorptionmdasha reviewrdquo Chemical EngineeringJournal vol 171 no 3 pp 811ndash840 2011

[13] M G Sujana and S Anand ldquoFluoride removal studies fromcontaminated groundwater by using bauxiterdquoDesalination vol267 no 2-3 pp 222ndash227 2011

[14] A Ramdani S Taleb A Benghalem and N GhaffourldquoRemoval of excess fluoride ions from Saharan brackish waterby adsorption on natural materialsrdquo Desalination vol 250 no1 pp 408ndash413 2010

[15] S Vinitnantharat S Kositchaiyong and S ChiarakornldquoRemoval of fluoride in aqueous solution by adsorption on acidactivated water treatment sludgerdquo Applied Surface Science vol256 no 17 pp 5458ndash5462 2010

[16] B Kemer D Ozdes A Gundogdu V N Bulut C Duran andM Soylak ldquoRemoval of fluoride ions from aqueous solution bywaste mudrdquo Journal of Hazardous Materials vol 168 no 2-3pp 888ndash894 2009

[17] A Tor N Danaoglu G Arslan and Y Cengeloglu ldquoRemoval offluoride from water by using granular red mud batch and col-umn studiesrdquo Journal of Hazardous Materials vol 164 no 1 pp271ndash278 2009

[18] N Chen Z Zhang C Feng N Sugiura M Li and R ChenldquoFluoride removal from water by granular ceramic adsorptionrdquoJournal of Colloid and Interface Science vol 348 no 2 pp 579ndash584 2010

[19] K Biswas K Gupta and U C Ghosh ldquoAdsorption of fluorideby hydrous iron(III)-tin(IV) bimetal mixed oxide from theaqueous solutionsrdquo Chemical Engineering Journal vol 149 no1ndash3 pp 196ndash206 2009

[20] A Eskandarpour M S Onyango A Ochieng and S AsaildquoRemoval of fluoride ions from aqueous solution at low pHusing schwertmanniterdquo Journal of HazardousMaterials vol 152no 2 pp 571ndash579 2008

[21] N A Medellin-Castillo R Leyva-Ramos R Ocampo-Perez etal ldquoAdsorption of fluoride from water solution on bone charrdquoIndustrial and Engineering Chemistry Research vol 46 no 26pp 9205ndash9212 2007

[22] N Kawasaki F Ogata H Tominaga and I YamaguchildquoRemoval of fluoride ion by bone char produced from animalbiomassrdquo Journal of Oleo Science vol 58 no 10 pp 529ndash5352009

[23] R Leyva-Ramos J Rivera-Utrilla N A Medellin-Castillo andM Sanchez-Polo ldquoKinetic modeling of fluoride adsorptionfrom aqueous solution onto bone charrdquo Chemical EngineeringJournal vol 158 no 3 pp 458ndash467 2010

[24] M E Kaseva ldquoOptimization of regenerated bone char for flu-oride removal in drinking water a case study in TanzaniardquoJournal of Water and Health vol 4 no 1 pp 139ndash147 2006

[25] H Mjengera and G Mkongo ldquoAppropriate deflouridationtechnology for use in flourotic areas in Tanzaniardquo Physics andChemistry of the Earth vol 28 pp 1097ndash1104 2003

[26] Y Tang X Guan J Wang N Gao M R McPhail and C CChusuei ldquoFluoride adsorption onto granular ferric hydroxide


effects of ionic strength pH surface loading and major co-existing anionsrdquo Journal of Hazardous Materials vol 171 no 1ndash3 pp 774ndash779 2009

[27] Y Tang X Guan T Su N Gao and J Wang ldquoFluoride adsorp-tion onto activated alumina modeling the effects of pH andsome competing ionsrdquoColloids and Surfaces A Physicochemicaland Engineering Aspects vol 337 no 1-3 pp 33ndash38 2009

[28] M Karthikeyan K K Satheesh Kumar and K P ElangoldquoConducting polymeralumina composites as viable adsorbentsfor the removal of fluoride ions from aqueous solutionrdquo Journalof Fluorine Chemistry vol 130 no 10 pp 894ndash901 2009

[29] V Sivasankar T Ramachandramoorthy and A DarchenldquoManganese dioxide improves the efficiency of earthenware influoride removal from drinking waterrdquo Desalination vol 272no 1ndash3 pp 179ndash186 2011

[30] M Mohapatra K Rout P Singh et al ldquoFluoride adsorptionstudies on mixed-phase nano iron oxides prepared by surfac-tant mediation-precipitation techniquerdquo Journal of HazardousMaterials vol 186 no 2-3 pp 1751ndash1757 2011

[31] S Smittakorn N Jirawongboonrod S Mongkolnchai-Arunyaand D Durnford ldquoHomemade bone charcoal adsorbent fordefluoridation of groundwater in Thailandrdquo Journal of Waterand Health vol 8 no 4 pp 826ndash836 2010

[32] S Lagergren ldquoZur theorie der sogenannten adsorption gelosterstofeerdquo Kungliga Svenska Vetenskapsakademiens Handlingarvol 24 no 4 pp 1ndash39 1898

[33] Y S Ho and G McKay ldquoPseudo-second order model forsorption processesrdquo Process Biochemistry vol 34 no 5 pp 451ndash465 1999

[34] H M F Freundlich Colloid and Capillary Chemistry Methuenand Co Ltd London UK 1926

[35] I Langmuir ldquoThe adsorption of gases on plane surfaces ofglassmica and platinumrdquoThe Journal of the AmericanChemicalSociety vol 40 no 9 pp 1361ndash1403 1918

[36] I Abe S Iwasaki T Tokimoto N Kawasaki T Nakamuraand S Tanada ldquoAdsorption of fluoride ions onto carbonaceousmaterialsrdquo Journal of Colloid and Interface Science vol 275 no1 pp 35ndash39 2004

[37] G He Y Chang and R Ji ldquoMechanisms of defluoridationof drinking water by tricalcium phosphaterdquo in Proceedingsof the 1st International Workshop on Fluorosis Prevention andDefluoridation of Water Ngurdoto Tanzania October 1995

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Environmental and Public Health

Journal of



EcosystemsJournal of


MeteorologyAdvances in

EcologyInternational Journal of


Marine BiologyJournal of


Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

Advances in


Environmental Chemistry

Atmospheric SciencesInternational Journal of



Waste ManagementJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

Geophysics


Geological ResearchJournal of

EarthquakesJournal of


BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OceanographyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


of phosphate Competing ions were found to have no effecton fluoride adsorption by other absorbents such as hydrousiron (III)-tin (IV) mixed oxide [19] polymer composites[28] and disposed earthenware [29] However sulfate andphosphate ions were found to compete with fluoride sorptionon materials with iron and aluminum bases [13] Chlorideand sulfate interfered with fluoride removal by mixed-phasenano iron oxides [30] All these experiments on the influenceof other ions on sorption were done with synthetic fluoridesolutions mixed with only single ion Actual groundwaterhowever contains multiple ions The interactions of theseions on fluoride sorption of bone char have not been welltested

There is a clear need inThailand to develop a point-of-usedefluoridator that will be successful in rural areas ofThailandthat are experiencing high fluoride levels In a previous paperby the authors [31] a simple method of producing bone charfor a point-of-use defluoridator in rural areas of Thailand isdescribed The boiled cow bone from a gelatin productionfactory is the raw material The homemade furnace consistsof a 20-liter recycled steel tank The boiled bone is placedin the middle of the tank surrounded by rice husks Afterclosing the lid of the tank the burning process takes about 8hours at which time the temperature reaches 500∘C to 600∘CThe bone char is left in the container to cool down for 24hours The advantages of the method compared to previousmethods include elimination of the need for the user tohandle fresh bone the use of small homemade furnacesno offensive smell during the burning process no need forchemical additives during the process and no requirementfor crushing or sieving of the bone at the local level Thesedifferences address societal and physical constraints in ruralareas of Thailand

The purpose of this paper is to report the results of a studyof the adsorption properties of theThai homemade bone charreferred to as THAI BC in this paper The kinetics of theadsorption process are investigated The effect of the size ofthe homemade bone char is studied to insure that the simpleproduction of homemade bone char will yield reasonableresults for fluoride removal without further crushing of thebone Results are compared to those of Indian bone char(IND BC) which is widely accepted and effectively used asan adsorbent in the removal of fluoride in India and otherareas worldwide The sorption ability of the Thai homemadebone char was also evaluated using natural groundwaterNatural groundwater contains multiple component ions Theresearch presented here addresses the influence of these otherions on fluoride removal In addition fluoride-contaminatedgroundwater samples were collected from several sites inChachengsao Phetchaburi and Nakorn Pathom provinces ofThailand

2 Materials and Methods

Boiled cow bone courtesy of the Thai Bone Industry inPathumThani province Thailand was the raw material Twoadvantages of using boiled bone instead of fresh bone are thehygienic handling of the bone and the lack of an offensive

odor during the charring process A homemade furnace ismade from a 200-litre steel container It should be noted thatthe size of the steel container has been increased from theprevious work so that more bone char can be produced Ricehusks are used as fuel Dried rice leaves were initially testedhowever the heat generated from the leaves was less than500∘C resulting in a poorer quality of bone char Rice husksare well known as an alternative renewable fuel A stainlesssteel pot is filled with about 7 kg of the boiled bone and placedon top of the rice husk The lid is closed and rice husks areadded until the pot is covered The fire is lit and rice husksfill the whole container Typically heat is applied for about 8hours with bone char being left to cool for about 24 hoursbefore it is removed About 5 kg of bone char is left fromthe process In this paper this bone char is referred to asTHAI BC The length of the bone char produced is about 1to 3 cm As discussed by Smittakorn et al [31] for acceptancein Thailand the production of the homemade bone char hasto be simple and to require no added chemicals no sievingor crushing during the process readily available local rawmaterials and no need for small households to handle thefresh bone

A series of batch experiments were conducted to assessthe effect of bone char size on the fluoride removal abilityThe bone char was crushed with a mortar and pestle andthen sieved into four different sizes which were less than0841mm 0841ndash118mm 119ndash237mm and 238ndash474mmIn these tests 200mL of a synthetic fluoride aqueous solutionwith a concentration of 39mgL was mixed with 10 g of thehomemade bone char in a plastic bottle and then shaken in awater bath at room temperature Samples were collected andanalyzed at 2 4 6 8 10 12 16 20 and 24 hours Sorptionkinetics and isotherms for each size of bone char were thenanalyzed

The fluoride sorption capacity of the Thai bone char(THAI BC) was then compared to that of Indian bone charIndian bone char (IND BC) was set as a benchmark since itis successfully used in India and elsewhere For these testssix groundwater samples were collected from wells at sites inChachengsao Phetchaburi and Nakorn Pathom provinces ofThailand The groundwater was stored in plastic containersand kept refrigerated prior to the sorption tests The fluorideconcentrations of the groundwater samples (designated asGW1 to GW6) ranged from 3 to 19mgL while the syntheticfluoride concentrationwas again 39mgL Procedures for thebatch experiments are as described above

The final tests presented in this paper investigate the effectof multiple ions on the sorption ability of bone charTheThaiand Indian bone chars were compared for sorption capacityusing a synthetic solution and a second set of groundwatersamples from six locations in Chachengsao Phetchaburi andNakorn Pathom provinces of Thailand These were collectedfrom different wells from the isotherm experiment and aredesignated as Sites 1 through 6 Samples were taken at thetime to equilibrium assumed to be 12 hours Again batch testsprocedures are described above

Fluoride and other ion concentrations were measuredusing the ion analyzer EA 940 at the analytical labora-tory of the Dental Health Division Department of Health



Size of BC(mm)

119902119890

(mgg)(experiment)


(hminus1) 119902119890

(mgg) 1198772

1198961

(hminus1) 119902119890

(mgg) 1198772

1198962


(mgg) 1198772



minus3

0102030405060708090

100

0 5 10 15 20 25 30

Adso

rptio

n (

)

Time (hour)













119902119890

minus 119902119905

= 119902119890

minus 1198960

119905 (1)

where 119902119890

and 119902119905


0


119890

minus 119902119905

)


is given by

log (119902119890

minus 119902119905

) = log 119902119890

minus

1198961

2303

119905 (2)




119905

119902119905

=

1

1198962

1199022

119890

+

119905

119902119890

(3)





119890


119890





119890



119902119890

= 119870119889

119862119890

1119899

(4)

where 119902119890


119890


119889


log (119902119890

) = log (119870119889

) +

1

119899

log (119862119890

) (5)



119902119890

=

119902119898

119870119860

119862119890

1 + 119870119860

119862119890

(6)

where 119862119890


119890


119898



119890

and (119862119890

119902119890

)

119862119890

119902119890

=

119862119890

119902119898

+

1

119870119860

119902119898

(7)



119889






1119899 1198772

119902119890

119870119860

1198772







119890



and 119870119860







Sample 119870119889

1119899 1198772










Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC





acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)




3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics
















Size of BC(mm)

119902119890

(mgg)(experiment)


(hminus1) 119902119890

(mgg) 1198772

1198961

(hminus1) 119902119890

(mgg) 1198772

1198962


(mgg) 1198772



minus3

0102030405060708090

100

0 5 10 15 20 25 30

Adso

rptio

n (

)

Time (hour)













119902119890

minus 119902119905

= 119902119890

minus 1198960

119905 (1)

where 119902119890

and 119902119905


0


119890

minus 119902119905

)


is given by

log (119902119890

minus 119902119905

) = log 119902119890

minus

1198961

2303

119905 (2)




119905

119902119905

=

1

1198962

1199022

119890

+

119905

119902119890

(3)





119890


119890





119890



119902119890

= 119870119889

119862119890

1119899

(4)

where 119902119890


119890


119889


log (119902119890

) = log (119870119889

) +

1

119899

log (119862119890

) (5)



119902119890

=

119902119898

119870119860

119862119890

1 + 119870119860

119862119890

(6)

where 119862119890


119890


119898



119890

and (119862119890

119902119890

)

119862119890

119902119890

=

119862119890

119902119898

+

1

119870119860

119902119898

(7)



119889






1119899 1198772

119902119890

119870119860

1198772







119890



and 119870119860







Sample 119870119889

1119899 1198772










Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC





acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)




3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics

















119890



119902119890

= 119870119889

119862119890

1119899

(4)

where 119902119890


119890


119889


log (119902119890

) = log (119870119889

) +

1

119899

log (119862119890

) (5)



119902119890

=

119902119898

119870119860

119862119890

1 + 119870119860

119862119890

(6)

where 119862119890


119890


119898



119890

and (119862119890

119902119890

)

119862119890

119902119890

=

119862119890

119902119898

+

1

119870119860

119902119898

(7)



119889






1119899 1198772

119902119890

119870119860

1198772







119890



and 119870119860







Sample 119870119889

1119899 1198772










Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC





acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)




3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics



















Sample 119870119889

1119899 1198772










Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC





acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)




3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics
















Sample 119902119890

119870119860

1198772


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC


000

005

010

015

020

025

030


Sorb

edFminus

per w

t of

BC

(mg

g)

THAI BCIND BC





acidic pH

Ca3

(PO4

)2

+ 3H2

O + 6Fminus

997888rarr Ca3

PO4

(HF2

)3

+ PO4

3minus

+ 3OHminus(8)




3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics

















3

minus SO4

2minus PO4

3minus




neutral pH

Ca3

(PO4

)2

+ 2H2

O + 4Fminus

997888rarr Ca3

PO4

(HF2

)2

(OH) + PO4

3minus

+OHminus(9)

alkaline pH

Ca3

(PO4

)2

+ 2H2

O + 2Fminus

997888rarr Ca3

PO4

(HF2

) (OH)2

+ PO4

3minus

+H+(10)


4 Conclusions




Notations


119862119861











119896119901




119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics
















119902119890


119902119898


119902119905


119905 Time (h)



Acknowledgments


References












































Journal of












Volume 2014

Advances in









Geophysics































Journal of












Volume 2014

Advances in









Geophysics


















Journal of












Volume 2014

Advances in









Geophysics














Documents

Research Article Defluoridation with Locally Produced Thai