Research Article Equilibrium, Kinetics, and Thermodynamics of...

Research ArticleEquilibrium Kinetics and Thermodynamics of the Removal ofNickel(II) from Aqueous Solution Using Cow Hooves

I Osasona1 O O Ajayi2 and A O Adebayo2

1 Department of Chemical Sciences Afe Babalola University PMB 5454 Ado-Ekiti Nigeria2 Department of Chemistry Federal University of Technology PMB 704 Akure Nigeria

Correspondence should be addressed to I Osasona oosasonayahoocom

Received 16 January 2014 Accepted 30 April 2014 Published 19 May 2014

Academic Editor Jeffrey M Zaleski

Copyright copy 2014 I Osasona et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The feasibility of using powdered cowhooves (CH) for removingNi2+ fromaqueous solutionwas investigated through batch studiesThe study was conducted to determine the effect of pH adsorbent dosage contact time adsorbent particle size and temperature onthe adsorption capacity of CH Equilibrium studies were conducted using initial concentration ofNi2+ ranging from 15 to 100mgLminus1at 208 308 and 318 K respectively The results of our investigation at room temperature indicated that maximum adsorption ofNi2+ occurred at pH 7 and contact time of 20 minutes The thermodynamics of the adsorption of Ni2+ onto CH showed that theprocess was spontaneous and endothermic Langmuir Freundlich and Dubinin-Radushkevich (D-R) isotherm models were usedto quantitatively analysed the equilibrium data The equilibrium data were best fitted by Freundlich isotherm model while theadsorption kinetics was well described by pseudo-second-order kinetic equation The mean adsorption energy obtained from theD-R isotherm revealed that the adsorption process was dominated by physical adsorption Powdered cow hooves could be utilizedas a low-cost adsorbent at room temperature under the conditions of pH 7 and a contact time of 20 minutes for the removal ofNi(II) from aqueous solution

1 Introduction

Heavy metal pollution is a global menace that has threatenedthe existence of lives for decades Heavy metals are partic-ularly injurious to plants and animals because of their non-biodegradability persistency and bioaccumulation tendency[1 2] Nickel can be introduced to the aquatic environmentthrough raw wastewater streams from industrial activitiessuch asmineral processing paint formulation electroplatingporcelain enameling copper sulphate manufacture man-ufacture of alloys silver refining zinc base casting andstorage battery industries and mining [3ndash5] Nickel is anessential micronutrient in animals and cofactor for enzymeurease in plants [4] It has also been pointed out that anenzyme (a nickel containing enzyme) called carbon monox-ide dehydrogenase (CODH) performs an important role inthe global carbon cycle This is because CODH is involvedin the interconversion of the environmental pollutant COand the greenhouse gas CO

2[6] Even though nickel plays

some important roles as an essential micronutrientenzymecofactor and carbon dioxide sequestering agent in the envi-ronment excessive concentrations of Ni in animals mightcause serious health challenges like gastrointestinal distresspulmonary fibrosis skin dermatitis cyanosis nausea tight-ness of the chest dry cough and shortness of breath rapidrespiration and so forth [4 7 8]

The maximum allowable discharge concentration of Ni2+is 2mgL [9] while its permissible limit in drinking water is05mgL [10] To attain these standards aqueous dischargefrom industrial activities must be treated before being emp-tied into the environment To this end a number of conven-tional techniques have been used to remove nickel(II) ionfrom industrial effluents This includes the use of activatedcarbon chemical precipitation and crystallization in theform of nickel carbonate [3] reverse osmosis coagulationand floatation [11] However these treatment methods areassociated with a lot of inherent limitations which includehigh capital and operational cost generation of secondary

Hindawi Publishing CorporationAdvances in Physical ChemistryVolume 2014 Article ID 863173 8 pageshttpdxdoiorg1011552014863173

2 Advances in Physical Chemistry

wastes and low metal uptake particularly when initial metalconcentrations in wastewaters are low [12ndash14] This hasled to the search for cheap environmentally friendly andefficientmethod of removing heavymetals fromwastewatersAdsorption using activated carbon has proven to be anexcellent alternative However the use of activated carbonfor heavy metal remediation is limited due to its high costand loss during regeneration [15] Consequently attentionhas been diverted towards the use of low-cost adsorbents andbiomaterials which are by-products or the wastes from largescale industrial operations and agricultural waste materialsfor heavy metal removal from wastewater

A lot of researchers have worked on different low-costadsorbents for the removal of Ni(II) from aqueous solutionExamples are Trichoderma viride [4] waste tea [16] proto-nated rice bran [17] chemically modified saw dust (Dalbergiasissoo) [18] marine algal biomass [19] corncob [20] and soforth Most of these low-cost adsorbents have shown highadsorption capacity for Ni(II)

This study was aimed at studying the adsorptive prop-erty of cow hoof (an inedible spare part of cows) for theremoval of Ni from aqueous solution The influence of pHcontact time adsorbent particle size and sorbent mass onthe adsorption capacity of cow hoof were also investigatedThe equilibrium data obtained were analysed and modelledusing Langmuir Freundlich andDubinin-Radushkevich (D-R) isothermmodels The feasibility of the adsorption processwas determined using the data generated at different temper-atures to determine the thermodynamic parameters

2 Materials and Methods

21 Materials Cow hooves were obtained from a localabattoir along Ekiti StateUniversity Road Ado-Ekiti NigeriaThe hooves were thoroughly washed with distilled water andsun dried for a month After drying the hooves were againwashed with distilled water and dried in an oven maintainedat a temperature of 105∘C The oven dried hooves were laterground and sieved using sieves of mesh sizes 212 120583m 425 120583mand 850120583mA stock solution containing 1000mgLminus1 ofNi(II)was prepared using analytical grade NiSO

4sdot6H2O in a 1 L

standard flask Standard solutions of different concentrationsas might be required were later prepared from this stock

22 Batch Adsorption Studies Unless otherwise stated allexperiments were conducted at room temperature (298K) for1 h using 50mg Lminus1 Ni(II) solution and 05 g CH of particlesize 212 120583m Batch adsorption studies were carried out in150mL glass stoppered conical flasks each containing 50mLof Ni(II) solution Amixture of the adsorbent andNi solutionwas agitated at a constant speed using thermostaticwater bathshaker (SearchTech 82) The effect of initial solution pH (23 4 5 6 and 7) adsorbent particle size (212 120583m 425 120583mand 850 120583m) adsorbent dose (01 03 05 07 and 1 g) andcontact time (10 20 30 60 90 120 and 150mins) wasevaluated during the present study HI 2210 pHmetre HannaInstruments was used for pHmeasurement while 01MHClor 01MNaOH was used for pH adjustment The mixture

50

55

60

65

70

75

0 100 200 300 400 500 600 700 800 900Particle size

R(

)

Figure 1 Effect of particle size on the percentage removal ofNi2+ 119879 = 298K

of the adsorbent and the solution was filtered after agitationand the concentration of Ni2+ ion present in the filtrate wasdetermined using atomic absorption spectrometer (AAS)The amount of metal ions adsorbed at equilibrium per unitmass of adsorbent was determined according to the followingequation

119902119890=(119862119900minus 119862119890) 119881

119898 (1)

where 119898 is the mass of adsorbent (g) 119881 is the volume of thesolution (L) 119862

119900is the initial concentration of Ni (mgLminus1)

119862119890is the equilibrium concentration of Ni (mgLminus1) in the

filtrate and 119902119890is the amount ofmetal adsorbed at equilibrium

(mggminus1) The percentage adsorption (119877) was calculatedusing the following expression

119877 =(119862119900minus 119862119890) times 100

119862119900

(2)

23 Equilibrium Studies The isotherm studies for theremoval of Ni(II) from aqueous solution using CH wereconducted at different temperatures (298 308 and 318 K)by equilibrating 05 g of CH with Ni solution having initialconcentration ranging from 15 to 100mgLminus1 The optimumpH of 7 was maintained for these studies The samples werethen filtered and the filtrates were analysed for Ni(II) usingatomic absorption spectrometer (AAS)

3 Results and Discussion

31 Effect of Particle Size The particle size of an adsorbentplays a vital role in adsorption Smaller sized particles havea higher surface area which in turn favours adsorption andresults in a shorter equilibration time [21]This phenomenonwas supported by our result for the effect of CH particle sizeon the removal of Ni as presented in Figure 1 The figureshows that percentage removal of Ni decreased from 694to 5464 when the particle size was increased from 212 120583mto 850 120583mThis is due to the fact that adsorbent with smallerparticle size will contain higher number of particles (binding

Advances in Physical Chemistry 3

0102030405060708090

100

0 1 2 3 4 5 6 7 8pH

R(

)

Figure 2 Effect of pH on the removal of Ni by cow hoofpowder 119879 = 298K

sites) than equal amount of the same adsorbent with higherparticle size

32 Effect of pH Solution pH out of all factors influencingadsorption of metals from solution has been pointed outto play a major role in adsorption because it affects thesolution chemistry ofmetals and the activity of the functionalgroups of the adsorbent (particularly biological adsorbents)[22] The effect of pH on the removal of Ni2+ from aqueoussolution is presented in Figure 2 It can be observed that theremoval of nickel(II) ion increased with increase in pH andreached a maximum at pH 7 The percentage removal of Niwas observed to be sharp between pH 2 and pH 4 (frompercentage removal of 428 to 8622) while the extentof removal was observed to be somehow slow between pH4 and pH 7 (8622ndash8969) The sharp increase in nickeluptake between pH 2 and pH 4 cannot be explained by thechange in metal speciation since nickel will exist as free Ni2+at pH between 2 and 4 and as such one would expect a verylow uptake of Ni2+ at this region because of the competitionthat would exist between H+ and Ni2+ ions Thus the ionicstates of the functional groups present on the surface of CHcan be used to explain the pH dependency of the removal ofNi2+ by CH Meanwhile it has been reported that biologicalmaterials primarily contain weak acidic and basic functionalgroups [23 24] Therefore in the acidic pH range 2ndash4 thebinding of heavymetal cations is determined primarily by thestate of dissociation of the weak acidic groups particularlycarboxyl groups (COOH) which are the most importantacidic groups formetal uptake by biologicalmaterials [23 25]The dissociation of this weak acidic functional group can berepresented as follows [26]

ndashCOOH 999448999471 COOminus +H+ (3)

At low pH the surface of the adsorbent is saturated withhydrogen ions this causes the equilibrium to be shifted tothe left thereby decreasing the amount of Ni2+ adsorbed [26]As the pH increases the number of hydrogen ions presentdecreases and this causes more COOminus ions to be exposed

0

1

2

3

4

5

6

7

10

20

30

40

50

60

70

80

90

0 02 04 06 08 1 12Sorbent mass (g)

qe (mgg)

qe

(mg

g)

R(

)

R ()

Figure 3 Effect of sorbent dosage on the removal of Ni2+ by cowhoof pH = 2 and 119879 = 298K

thereby increasing the amount of Ni2+ adsorbed Summarilyat low pH the overall surface charge on the adsorbent (CH)became positive and this created a repulsive force between thepositively charged Ni(II) ions and the CH surface Maximumpercentage removal of Ni(II) was observed at pH 7 thereforepH 7 was used for other experiments

33 Effect of Sorbent Dosage The influence of sorbent dosageon the percentage removal of Ni is illustrated in Figure 3It reveals that increase in the amount of CH dosed broughtabout the increase in the percentage of Ni removed Thepercentage of Ni removed from aqueous phase to the CHsurface increased from 2345 to 8292 when the amount ofCH dosed was increased from 01 to 1 g The increase in thepercentage Ni(II) adsorption with an increase in adsorbentconcentration can be attributed to increase in the surfacearea of the adsorbent which in turn increased the numberof binding sites Conversely uptake of Ni(II) per unit weight(119902) of CH decreased with increase in the concentration ofCH dosedThe uptake capacity of Ni(II) decreased from 586to 207mggminus1 when the concentration of CH was increasedfrom 01 to 1 g (Figure 3) This can be linked to the fact thatthe unchanging amount of solute is insufficient to completelycover the increasing available exchangeable sites on theadsorbent surfaceMoreover interferences could exist amongthe binding sites at high concentrations of the adsorbent[27 28]

34 Adsorption Kinetics Figure 4 presents the effect of con-tact time on the adsorption of Ni(II) by cow hoof powderTheoptimumpercentage (785) adsorptionwas reached after 20minutes of agitation The figure reveals that adsorption of Nion CH was rapid within the first 10 minutes and the processwas brought to equilibrium after 20 minutes of agitation

A lot of models have been used in the literature toquantitatively describe the kinetic behaviour of adsorptionprocesses of biomaterials Of these pseudo-first-order (4)


0102030405060708090

0 20 40 60 80 100 120 140 160Time (min)

R(

)

Figure 4 Effect of contact time on the percentage removal of Ni2+by cow hoof

05

1015202530354045

0 20 40 60 80 100 120 140 160Time (min)

tqt

(g m

inm

g)

R2 = 0999

Figure 5 Pseudo-second-order kinetic plot for the removal ofNi(II)by CH

and pseudo-second-order (5) models were used to describethe adsorption kinetic of the removal of Ni(II) by CH

Consider

log (119902119890minus 119902119905) = log 119902

119890minus1198961119905

2303 (4)

119905

119902119905

=1

11989621199022119890

+1

119902119890

119905 (5)

where 1198961is the rate constant for first-order equation (minminus1)

119902119890is the amount of metal adsorbed at equilibrium (mggminus1)119902119905is the amount of Ni(II) adsorbed at time 119905 (mggminus1) and 119896

2

is the second-order adsorption rate constant (gmgminus1minminus1)The adsorption in this study data was well fitted by thepseudo-second-order model with correlation coefficient of0999 (Figure 5) The pseudo-first-order model could notdescribe these data because the process was brought toequilibrium within a short period of time

35 Adsorption Equilibrium The adsorption capacity of CH(at 298 308 and 318 K) forNi(II) removalwas evaluated usingthe following two parameters adsorption isotherm modelsLangmuir Freundlich and Dubinin-Radushkevich (D-R)TheLangmuir isotherm is based on the assumption thatmetal

ions are adsorbed independently at a fixed number of well-defined energetically equivalent sites and that each site canonly hold one ion [23] It is then assumed that once a metalion occupies a site no further sorption can take place Thissuggests that there is no migration or interaction betweenthe adsorbed ions on the surface of the adsorbent [29] Thismodel can be expressed as

119902 =119902119898119870119871119862119890

1 + 119870119871119862119890

(6)

This can be linearized to obtain

119862119890

119902119890

=1

119870119871119902119898

+119862119890

119902119898

(7)

where 119902119898(mggminus1) is the maximum adsorption capacity and

119870119871(Lmgminus1) is a constant related to the affinity of binding sites

or bonding energyThe Freundlich model which is based on the assumption

that adsorption occurs on a heterogeneous surface can beexpressed as

119902119890= 1198701198651198621119899 (8)

This can be linearized by taking the logarithm of both sidesof the equation to give

log 119902119890= log119870

119865+1

119899log119862119890 (9)

where 119902119890(mggminus1) is the metal uptake at equilibrium 119862

119890

(mgLminus1) is the equilibrium concentration of the metal and119870119865and 1119899 are the Freundlich constants related to adsorp-

tion capacity and affinity between the adsorbent and themetal respectively

The Dubinin-Radushkevich (D-R) isotherm which alsoassumes a heterogeneous surface is expressed as follows

119902119890= 119902119863119890minus119870119863120576

2

(10)

This can be linearized as

ln 119902119890= ln 119902

119863minus 1198701198631205762 (11)

where 120576 is the Polanyi potential = 119877119879 ln(1 + 1119862119890) 119902119863is

the adsorption capacity of the adsorbent (mggminus1) 119870119863is a

constant related to the adsorption energy (mol2 kJminus2)119877 is thegas constant (kJKminus1molminus1) and119879 is the temperature (K)Themean adsorption energy can be determined fromD-Rmodelusing the relationship

119864 = (minus2119870119863)minus12

(12)

The maximum adsorption capacities adsorption constantsand the correlation coefficients obtained for the threeisotherm models at different temperatures are presented inTable 1 It follows from the table that the Freundlich isothermmodel fitted the equilibrium data better than the Langmuirand D-R models at all temperatures (Table 1 and Figure 6)


Table 1 Isotherm parameters for the removal of Ni(II) by CH at different temperatures

Isotherm Parameter Temperature (K)298 308 318

Langmuir119902119898(mggminus1) 1023 1057 1124119870119871(Lmgminus1) 00574 04188 041341198772 06781 09230 09516

Freundlich119870119865(L1119899 gminus1mg1119899) 08513 29187 3059119899 16425 1992 192861198772 09445 09921 09581

D-R

119902119863(mggminus1) 485 641 7122

119870119863(mol2KJminus2) minus14508 minus01024 minus01181119864 (KJmolminus1) 0587 2209 20581198772 07670 08488 09171

0

02

04

06

08

1

12

14

0 05 1 15 2minus1 minus05minus02

log

log

qe

Ce

298K308K318K

R2 = 09581

R2 = 09921

R2 = 09445

Figure 6 Freundlich isotherm plots for the removal of Ni using cowhoof pH = 7 119905 = 30minutes and sorbent mass = 05 g

Themaximum adsorption capacities (119902119898119870119891 and 119902

119863) for the

three models increased with increase in temperature from298K to 318 KThis is an indication of endothermic process

The Langmuir constant 119870119871explains the affinity between

the adsorbent and the adsorbate in terms of a dimensionlessparameter called separation factor 119877

119871 119877119871values can be

obtained using

119877119871=1

1 + 119870119871119862119900

(13)

where119862119900is the initial concentration ofmetal (mgLminus1) and119870

119871

is Langmuir constantIf 119877119871= 0 the adsorption process is irreversible if 0 lt

119877119871lt 1 the process is said to be favourable and if 119877

119871gt

1 the process is unfavourable The 119877119871values in this study

are shown in Figure 7 The figure indicates that adsorptionwas favourable at all concentrations considered but morefavourable at highNi(II) concentrations (all119877

119871values are less

than 1)This implies that the removal ofNi(II) from aqueous solu-

tion increased when the concentration of Ni was increased

0

01

02

03

04

05

06

0 20 40 60 80 100 120

RL

Co (mgL)

298K308K318K

Figure 7 Separation factor plots for the removal Ni(II) by CH atdifferent temperatures

from 15 to 100 mgLminus1 It can also be observed from the figurethat the process was more favourable at high temperaturesThis further supports the endothermic nature of the removalof Ni by CH However the extent of favourability seems to beinsignificant when the temperature was increased from 308to 318 K (Figure 7)

The Freundlich constant 119899 can also be used to predict thefavourability of the adsorption process [21 30] The valuesof 119899 in this study are between 1 and 10 (Table 1) This is anindication of favourability of the process

The Langmuir and Freundlich isotherm constants areuseful in predicting the favourability of the removal ofNi(II) by CH but cannot explain the chemical or physicalproperties of the process However the mean adsorptionenergy (119864) calculated from the D-R isotherm can provideuseful information about these properties [30] An adsorp-tion process is said to be dominated by physical adsorption if119864 lt 8 kJmolminus1 and by chemical adsorption if 119864 gt 8 kJmolminus1[30]Therefore the removal of Ni(II) by CH can be describedto be dominated by physical adsorption at all temperatures(Table 1)


0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579

Figure 8 A plot of surface coverage against initial Ni(II) concentra-tion

36 Surface Coverage (120579) To account for the adsorptionbehaviour of Ni(II) ions on CH the Langmuir type equa-tion related to surface coverage was used The equation isexpressed as follows

120579

(1 minus 120579)= 119870119871119862119900 (14)

where119870119871is the Langmuir adsorption coefficient and119862

119900is the

initial Ni(II) concentration (mgLminus1)The values of the surfacecoverage (120579) at all temperatures considered were plottedagainst initial Ni(II) ions concentration (Figure 8)The figureshows that increase in initial metal ion concentration ofnickel brought about increase in the surface coverage on theadsorbent (CH) until the surface was nearly fully coveredwith a monolayer (Figure 8)

Figure 8 also reveals that increase in temperature from298 to 308K increased the surface coverage while surfacecoverage seemed to be independent of temperature when thetemperature was increased from 308 to 318 K as the plots forboth temperatures seem to overlap on each other

37 Adsorption Thermodynamics The changes in Gibbs freeenergy (Δ119866) enthalpy (Δ119867) and entropy (Δ119878) for the adsorp-tion process were obtained using the following equations

119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890

is the concentration of Ni(II) (mgLminus1) adsorbed atequilibrium119862

119890is the equilibrium concentration of the metal

in mgLminus1 119870119890is the equilibrium constant 119879 is temperature

in Kelvin and 119877 is the gas constant (kJmolminus1 Kminus1) The valueof 119870119890can be obtained from the lowest experimental Ni

concentration [31]

Table 2 Thermodynamic parameters for the removal of Ni by CHat different temperatures

T (K) ΔG∘ (kJmolminus1) ΔH∘ (kJmolminus1) ΔS∘ (kJmolminus1)298 minus565 6476 0236308 minus801318 minus1037

The values of the enthalpy change (Δ119867) and entropychange (Δ119878) were calculated from the slope and intercept ofthe plot of ln119870

119890against 1119879 (15) while the values of Δ119866 at

different temperatures were obtained using (17) The resultsof these thermodynamic parameters are presented in Table 2The negative values recorded for the Gibbs free energyat all temperatures are an indication that the adsorptionprocess was spontaneous and that the degree of spontaneityof the reaction increased with increase in temperature Thiscoupled with the positive value of the enthalpy changefurther supports the earlier suggestions that the process wasendothermic The positive value of the entropy change alsoindicates that entropy increases as a result of adsorptionThisoccurs as a result of redistribution of energy between Ni(II)ions and the adsorbent Before adsorption occurs the heavymetal ions near the surface of the adsorbent will be moreordered than in the subsequent adsorbed state [30]

38 FTIR Analysis The FTIR analysis of CH was conductedbefore and after the adsorption of Ni(II) ions to determinethe possible involvement of the functional groups present onCH surface in the adsorption process The spectra obtainedare presented in Figure 9 The spectroscopic characteristicsof these spectra are shown in Table 3 A critical observationof Table 3 and Figure 9 shows that virtually all the absorp-tion bands for these functional groups were shifted afteradsorption of Ni2+ Of all these shifts five prominent peakshad a decrease in their absorption bands after adsorptionof Ni(II) (Figure 9 and Table 3) These include absorption at236571 (ndashSndashH) 1658 60 (ndashC=O) 153058 (amino) 139300(nitro compound) and 123911 It can be suggested that thefunctional groups corresponding to these bands played animportant role in the adsorption of Ni(II) The involvementof these functional groups (particularly C=O and SndashH) in theremoval of Zn and the high positive enthalpy of the processcan make one assume that chemisorption took a prominentrole in the removal of Ni(II) [26]

4 Conclusion

The removal of Ni(II) from simulated wastewater using cowhoof was conducted Our results revealed that maximumremoval of Ni at room temperature could be achieved withina period of 20 minutes and at pH 7 Thermodynamic param-eters evaluated from this study showed that the adsorptionprocess was endothermic and spontaneous at all tempera-tures considered The kinetic modelling of the adsorptiondata suggested that chemisorption was the rate determiningstep since the data fitted well with pseudo-second-order


(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500

(a) Cow hoof after adsorption of Ni2+

(b) Cow hoof before adsorption

331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)

Wave number (cmminus1)

Figure 9 FTIR spectra of CH (a) after adsorption of Ni2+ and (b) before adsorption

Table 3 FTIR spectral characteristics of CH before and after Ni (II) removal

IR peak Frequency (cmminus1) before adsorption Frequency (cmminus1) after adsorption Difference Functional group1 331400 mdash mdash Bonded ndashOH group2 293142 294285 1143 Aliphatic CndashH groups3 236571 235428 minus1143 SndashH stretching4 165860 165233 minus627 C=O stretching5 153058 152694 minus364 Aminonitro compound6 139300 138730 minus570 Nitro compound7 123911 123341 minus570 CndashN stretching8 103963 105673 1710 CndashO stretching

model However the D-R isotherm model suggested that theremoval of Ni from aqueous solution using cow hooves wasdominated by physisorption Therefore it can be concludedthat both physical and chemical adsorption played a promi-nent role in the adsorption process additionally when theenthalpy change for the process was high

Conflict of Interests

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

References

[1] L C Ajjabi and L Chouba ldquoBiosorption of Cu2+ and Zn2+from aqueous solutions by dried marine green macroalgaChaetomorpha linumrdquo Journal of Environmental Managementvol 90 no 11 pp 3485ndash3489 2009

[2] I Osasona A O Adebayo and O O Ajayi ldquoBiosorption ofPb (II) from aqueous solution using cow hooves kinetics andthermodynamicsrdquo ISRN Physical Chemistry vol 2013 ArticleID 171865 8 pages 2013

[3] V Padmavathy P Vasudevan and S C Dhingra ldquoBiosorptionof nickel(II) ions on Bakerrsquos yeastrdquo Process Biochemistry vol 38no 10 pp 1389ndash1395 2003

[4] P Sujatha V Kalarani and B N Kumar ldquoEffective biosorptionof nickel (II) from Aqueous solution using Trichoderma viriderdquoJournal of Chemistry vol 2013 Article ID 716098 7 pages 2013

[5] M Sitting Toxic MetalsmdashPollution Control and Worker Protec-tion Noyes Data Corporation Park Ridge NJ USA 1976

[6] Y Kung and C L Drennan ldquoA role for nickel-iron cofactorsin biological carbon monoxide and carbon dioxide utilizationrdquoCurrent Opinion in Chemical Biology vol 15 no 2 pp 276ndash2832011

[7] C E Borba R Guirardello E A Silva M T Veit and C R GTavares ldquoRemoval of nickel(II) ions from aqueous solution bybiosorption in a fixed bed column experimental and theoretical


breakthrough curvesrdquo Biochemical Engineering Journal vol 30no 2 pp 184ndash191 2006

[8] A K Meena G K Mishra P K Rai C Rajagopal and P NNagar ldquoRemoval of heavy metal ions from aqueous solutionsusing carbon aerogel as an adsorbentrdquo Journal of HazardousMaterials vol 122 no 1-2 pp 161ndash170 2005

[9] H D Doan J Wu and R Mitzakov ldquoCombined electro-chemical and biological treatment of industrial wastewaterusing porous electrodesrdquo Journal of Chemical Technology andBiotechnology vol 81 no 8 pp 1398ndash1408 2006

[10] World Health Organization Guidelines for Drinking-WaterQuality Incorporating First Addendum to Third Edition vol 1World Health Organization Geneva Switzerland 3rd edition2006

[11] I Mobasherpour E Salahi andM Pazouki ldquoRemoval of nickel(II) from aqueous solutions by using nano-crystalline calciumhydroxyapatiterdquo Journal of Saudi Chemical Society vol 15 no2 pp 105ndash112 2011

[12] M A Tofighy and T Mohammadi ldquoAdsorption of divalentheavy metal ions from water using carbon nanotube sheetsrdquoJournal of Hazardous Materials vol 185 no 1 pp 140ndash147 2011

[13] M A Khan R A K Rao and M Ajmal ldquoHeavy metalpollution and its control through nonconventional adsorbents(1998ndash2007) a reviewrdquo Journal of International EnvironmentalApplication and Science vol 3 no 2 pp 101ndash141 2008

[14] N Kuyucak and B Volesky ldquoBiosorbents for recovery of metalsfrom industrial solutionsrdquo Biotechnology Letters vol 10 no 2pp 137ndash142 1988

[15] D SudGMahajan andM P Kaur ldquoAgricultural wastematerialas potential adsorbent for sequestering heavy metal ions fromaqueous solutionsmdasha reviewrdquo Bioresource Technology vol 99no 14 pp 6017ndash6027 2008

[16] P E Aikpokpodion R R Ipinmoroti and S M OmotosoldquoBiosorption of nickel (II) from aqueous solution using wastetea (Camella cinencis) materialsrdquo The American-Eurasian Jour-nal of Toxicological Sciences vol 2 no 2 pp 72ndash82 2010

[17] MN Zafar R Nadeem andMAHanif ldquoBiosorption of nickelfrom protonated rice branrdquo Journal of HazardousMaterials vol143 no 1-2 pp 478ndash485 2007

[18] H Rehman M Shakirullah I Ahmad S Shah and HHameedullah ldquoSorption studies of nickel ions onto sawdust ofDalbergia sissoordquo Journal of the Chinese Chemical Society vol53 no 5 pp 1045ndash1052 2006

[19] P X Sheng Y-P Ting J P Chen andLHong ldquoSorption of leadcopper cadmium zinc and nickel by marine algal biomasscharacterization of biosorptive capacity and investigation ofmechanismsrdquo Journal of Colloid and Interface Science vol 275no 1 pp 131ndash141 2004

[20] Z Reddad CGerente Y Andres and P LeCloirec ldquoAdsorptionof several metal ions onto a low-cost biosorbent kinetic andequilibrium studiesrdquo Environmental Science and Technologyvol 36 no 9 pp 2067ndash2073 2002

[21] K Vijayaraghavan and Y-S Yun ldquoBacterial biosorbents andbiosorptionrdquoBiotechnologyAdvances vol 26 no 3 pp 266ndash2912008

[22] A Esposito F Pagnanelli and F Veglio ldquopH-related equilibriamodels for biosorption in single metal systemsrdquo ChemicalEngineering Science vol 57 no 3 pp 307ndash313 2002

[23] L Norton K Baskaran and T McKenzie ldquoBiosorption ofzinc from aqueous solutions using biosolidsrdquo Advances inEnvironmental Research vol 8 no 3-4 pp 629ndash635 2004

[24] M Riaz R Nadeem M A Hanif T M Ansari and K-URehman ldquoPb(II) biosorption from hazardous aqueous streamsusing Gossypium hirsutum (Cotton) waste biomassrdquo Journal ofHazardous Materials vol 161 no 1 pp 88ndash94 2009

[25] K H Kok M I A Karim A Ariff and S A Aziz ldquoRemoval ofcadmium copper and lead from tertiary metals system usingbiomass of Aspergillus flavusrdquo Pakistan Journal of BiologicalSciences vol 5 no 4 pp 474ndash478 2002

[26] I Osasona O O Ajayi and A O Adebayo ldquoEquilibriumkinetics and thermodynamics of the biosorption of Zn (II) fromaqueous solution using powdered cow hoovesrdquo ISRN PhysicalChemistry vol 2013 Article ID 865219 7 pages 2013

[27] J Tangaromsuk P Pokethitiyook M Kruatrachue and E SUpatham ldquoCadmium biosorption by Sphingomonas paucimo-bilis biomassrdquo Bioresource Technology vol 85 no 1 pp 103ndash1052002

[28] G M Gadd P R Norris and D P Kelly ldquoHeavy metal andradionuclide by fungi and yeastsrdquo in Biohydrometallurgy ARowe Ed Chippenham Wilts UK 1988

[29] G M Gadd ldquoHeavy metal accumulation by bacteria and othermicroorganismsrdquo Experientia vol 46 no 8 pp 834ndash840 1990

[30] M E Argun S Dursun C Ozdemir and M Karatas ldquoHeavymetal adsorption by modified oak sawdust thermodynamicsand kineticsrdquo Journal of Hazardous Materials vol 141 no 1 pp77ndash85 2007

[31] R Han W ZouW Yu S Cheng Y Wang and J Shi ldquoBiosorp-tion of methylene blue from aqueous solution by fallen phoenixtreersquos leavesrdquo Journal of Hazardous Materials vol 141 no 1 pp156ndash162 2007

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


wastes and low metal uptake particularly when initial metalconcentrations in wastewaters are low [12ndash14] This hasled to the search for cheap environmentally friendly andefficientmethod of removing heavymetals fromwastewatersAdsorption using activated carbon has proven to be anexcellent alternative However the use of activated carbonfor heavy metal remediation is limited due to its high costand loss during regeneration [15] Consequently attentionhas been diverted towards the use of low-cost adsorbents andbiomaterials which are by-products or the wastes from largescale industrial operations and agricultural waste materialsfor heavy metal removal from wastewater

A lot of researchers have worked on different low-costadsorbents for the removal of Ni(II) from aqueous solutionExamples are Trichoderma viride [4] waste tea [16] proto-nated rice bran [17] chemically modified saw dust (Dalbergiasissoo) [18] marine algal biomass [19] corncob [20] and soforth Most of these low-cost adsorbents have shown highadsorption capacity for Ni(II)

This study was aimed at studying the adsorptive prop-erty of cow hoof (an inedible spare part of cows) for theremoval of Ni from aqueous solution The influence of pHcontact time adsorbent particle size and sorbent mass onthe adsorption capacity of cow hoof were also investigatedThe equilibrium data obtained were analysed and modelledusing Langmuir Freundlich andDubinin-Radushkevich (D-R) isothermmodels The feasibility of the adsorption processwas determined using the data generated at different temper-atures to determine the thermodynamic parameters

2 Materials and Methods

21 Materials Cow hooves were obtained from a localabattoir along Ekiti StateUniversity Road Ado-Ekiti NigeriaThe hooves were thoroughly washed with distilled water andsun dried for a month After drying the hooves were againwashed with distilled water and dried in an oven maintainedat a temperature of 105∘C The oven dried hooves were laterground and sieved using sieves of mesh sizes 212 120583m 425 120583mand 850120583mA stock solution containing 1000mgLminus1 ofNi(II)was prepared using analytical grade NiSO

4sdot6H2O in a 1 L

standard flask Standard solutions of different concentrationsas might be required were later prepared from this stock

22 Batch Adsorption Studies Unless otherwise stated allexperiments were conducted at room temperature (298K) for1 h using 50mg Lminus1 Ni(II) solution and 05 g CH of particlesize 212 120583m Batch adsorption studies were carried out in150mL glass stoppered conical flasks each containing 50mLof Ni(II) solution Amixture of the adsorbent andNi solutionwas agitated at a constant speed using thermostaticwater bathshaker (SearchTech 82) The effect of initial solution pH (23 4 5 6 and 7) adsorbent particle size (212 120583m 425 120583mand 850 120583m) adsorbent dose (01 03 05 07 and 1 g) andcontact time (10 20 30 60 90 120 and 150mins) wasevaluated during the present study HI 2210 pHmetre HannaInstruments was used for pHmeasurement while 01MHClor 01MNaOH was used for pH adjustment The mixture

50

55

60

65

70

75

0 100 200 300 400 500 600 700 800 900Particle size

R(

)

Figure 1 Effect of particle size on the percentage removal ofNi2+ 119879 = 298K

of the adsorbent and the solution was filtered after agitationand the concentration of Ni2+ ion present in the filtrate wasdetermined using atomic absorption spectrometer (AAS)The amount of metal ions adsorbed at equilibrium per unitmass of adsorbent was determined according to the followingequation

119902119890=(119862119900minus 119862119890) 119881

119898 (1)

where 119898 is the mass of adsorbent (g) 119881 is the volume of thesolution (L) 119862

119900is the initial concentration of Ni (mgLminus1)

119862119890is the equilibrium concentration of Ni (mgLminus1) in the

filtrate and 119902119890is the amount ofmetal adsorbed at equilibrium

(mggminus1) The percentage adsorption (119877) was calculatedusing the following expression

119877 =(119862119900minus 119862119890) times 100

119862119900

(2)

23 Equilibrium Studies The isotherm studies for theremoval of Ni(II) from aqueous solution using CH wereconducted at different temperatures (298 308 and 318 K)by equilibrating 05 g of CH with Ni solution having initialconcentration ranging from 15 to 100mgLminus1 The optimumpH of 7 was maintained for these studies The samples werethen filtered and the filtrates were analysed for Ni(II) usingatomic absorption spectrometer (AAS)

3 Results and Discussion

31 Effect of Particle Size The particle size of an adsorbentplays a vital role in adsorption Smaller sized particles havea higher surface area which in turn favours adsorption andresults in a shorter equilibration time [21]This phenomenonwas supported by our result for the effect of CH particle sizeon the removal of Ni as presented in Figure 1 The figureshows that percentage removal of Ni decreased from 694to 5464 when the particle size was increased from 212 120583mto 850 120583mThis is due to the fact that adsorbent with smallerparticle size will contain higher number of particles (binding


0102030405060708090

100

0 1 2 3 4 5 6 7 8pH

R(

)






0

1

2

3

4

5

6

7

10

20

30

40

50

60

70

80

90

0 02 04 06 08 1 12Sorbent mass (g)

qe (mgg)

qe

(mg

g)

R(

)

R ()







0102030405060708090

0 20 40 60 80 100 120 140 160Time (min)

R(

)


05

1015202530354045

0 20 40 60 80 100 120 140 160Time (min)

tqt

(g m

inm

g)

R2 = 0999



Consider

log (119902119890minus 119902119905) = log 119902

119890minus1198961119905

2303 (4)

119905

119902119905

=1

11989621199022119890

+1

119902119890

119905 (5)



2




119902 =119902119898119870119871119862119890

1 + 119870119871119862119890

(6)


119862119890

119902119890

=1

119870119871119902119898

+119862119890

119902119898

(7)





119902119890= 1198701198651198621119899 (8)


log 119902119890= log119870

119865+1

119899log119862119890 (9)


119890




119902119890= 119902119863119890minus119870119863120576

2

(10)


ln 119902119890= ln 119902

119863minus 1198701198631205762 (11)




119864 = (minus2119870119863)minus12

(12)







D-R

119902119863(mggminus1) 485 641 7122


0

02

04

06

08

1

12

14


log

log

qe

Ce

298K308K318K

R2 = 09581

R2 = 09921

R2 = 09445



119863) for the




119871 119877119871values can be

obtained using

119877119871=1

1 + 119870119871119862119900

(13)


119871



119871gt






0

01

02

03

04

05

06

0 20 40 60 80 100 120

RL

Co (mgL)

298K308K318K






0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579



120579

(1 minus 120579)= 119870119871119862119900 (14)


119900is the




119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890





concentration [31]







4 Conclusion



(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0102030405060708090

100

0 1 2 3 4 5 6 7 8pH

R(

)






0

1

2

3

4

5

6

7

10

20

30

40

50

60

70

80

90

0 02 04 06 08 1 12Sorbent mass (g)

qe (mgg)

qe

(mg

g)

R(

)

R ()







0102030405060708090

0 20 40 60 80 100 120 140 160Time (min)

R(

)


05

1015202530354045

0 20 40 60 80 100 120 140 160Time (min)

tqt

(g m

inm

g)

R2 = 0999



Consider

log (119902119890minus 119902119905) = log 119902

119890minus1198961119905

2303 (4)

119905

119902119905

=1

11989621199022119890

+1

119902119890

119905 (5)



2




119902 =119902119898119870119871119862119890

1 + 119870119871119862119890

(6)


119862119890

119902119890

=1

119870119871119902119898

+119862119890

119902119898

(7)





119902119890= 1198701198651198621119899 (8)


log 119902119890= log119870

119865+1

119899log119862119890 (9)


119890




119902119890= 119902119863119890minus119870119863120576

2

(10)


ln 119902119890= ln 119902

119863minus 1198701198631205762 (11)




119864 = (minus2119870119863)minus12

(12)







D-R

119902119863(mggminus1) 485 641 7122


0

02

04

06

08

1

12

14


log

log

qe

Ce

298K308K318K

R2 = 09581

R2 = 09921

R2 = 09445



119863) for the




119871 119877119871values can be

obtained using

119877119871=1

1 + 119870119871119862119900

(13)


119871



119871gt






0

01

02

03

04

05

06

0 20 40 60 80 100 120

RL

Co (mgL)

298K308K318K






0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579



120579

(1 minus 120579)= 119870119871119862119900 (14)


119900is the




119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890





concentration [31]







4 Conclusion



(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0102030405060708090

0 20 40 60 80 100 120 140 160Time (min)

R(

)


05

1015202530354045

0 20 40 60 80 100 120 140 160Time (min)

tqt

(g m

inm

g)

R2 = 0999



Consider

log (119902119890minus 119902119905) = log 119902

119890minus1198961119905

2303 (4)

119905

119902119905

=1

11989621199022119890

+1

119902119890

119905 (5)



2




119902 =119902119898119870119871119862119890

1 + 119870119871119862119890

(6)


119862119890

119902119890

=1

119870119871119902119898

+119862119890

119902119898

(7)





119902119890= 1198701198651198621119899 (8)


log 119902119890= log119870

119865+1

119899log119862119890 (9)


119890




119902119890= 119902119863119890minus119870119863120576

2

(10)


ln 119902119890= ln 119902

119863minus 1198701198631205762 (11)




119864 = (minus2119870119863)minus12

(12)







D-R

119902119863(mggminus1) 485 641 7122


0

02

04

06

08

1

12

14


log

log

qe

Ce

298K308K318K

R2 = 09581

R2 = 09921

R2 = 09445



119863) for the




119871 119877119871values can be

obtained using

119877119871=1

1 + 119870119871119862119900

(13)


119871



119871gt






0

01

02

03

04

05

06

0 20 40 60 80 100 120

RL

Co (mgL)

298K308K318K






0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579



120579

(1 minus 120579)= 119870119871119862119900 (14)


119900is the




119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890





concentration [31]







4 Conclusion



(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






D-R

119902119863(mggminus1) 485 641 7122


0

02

04

06

08

1

12

14


log

log

qe

Ce

298K308K318K

R2 = 09581

R2 = 09921

R2 = 09445



119863) for the




119871 119877119871values can be

obtained using

119877119871=1

1 + 119870119871119862119900

(13)


119871



119871gt






0

01

02

03

04

05

06

0 20 40 60 80 100 120

RL

Co (mgL)

298K308K318K






0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579



120579

(1 minus 120579)= 119870119871119862119900 (14)


119900is the




119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890





concentration [31]







4 Conclusion



(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

02

04

06

08

1

12

0 20 40 60 80 100 120Co (mgL)

298K308K318K

Surfa

ce co

vera

ge120579



120579

(1 minus 120579)= 119870119871119862119900 (14)


119900is the




119870119890=119862119860119890

119862119890

(15)

ln119870119890= minusΔ119867

119877119879+Δ119878

119877 (16)

Δ119866 = Δ119867 minus 119879Δ119878 (17)

where119862119860119890





concentration [31]







4 Conclusion



(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a)

(b)

212

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

54640000 3000 2000 1500 1000 500 3500



331400

293142

294285

236571

235428

165860

165233

153058

152694

139300

138730

123911

123341

103963

105673

375428

376571

54133

35284

46113

46683

67202

53808

T(

)








References











































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Equilibrium, Kinetics, and Thermodynamics of...

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Transcript of Research Article Equilibrium, Kinetics, and Thermodynamics of...