GROUNDNUT SHELL: EFFECTIVE ADSORBENT FOR … · 2016-11-07 · pH was like 2, 4, 6,8,10 &12,...

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International Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 6, November-December 2016, pp. 51–60, Article ID: IJCIET_07_06_006

Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=6

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication

GROUNDNUT SHELL: EFFECTIVE ADSORBENT FOR

DEFLUORIDATION FROM AQUEOUS SOLUTION

Buddharatna Godboley and Prashant Nagarnaik

Civil Engineering Department, G.H. Raisoni College of Engineering Nagpur, India

ABSTRACT

Water defluoridation experiments were carried out on solid waste i.e Groundnut Shell (GS).

The 10 ppm fluoride concentration solution and 4.5gm of GS were employed in experiments to

determine defluoridation capacities, effects of pH and effects of temperature, effect of initial

concentration, and effect of contact time on defluoridation. The highest defluoridation capacity of

92.8% was obtained with the dose of 4.5g/L. The adsorption follows a Pseudo second order

kinetics, Elovich equation, Modified Freundlich equation. Equilibrium study is done and it follows

Langmuir, Freundlich, and Temkin isotherm. The value of thermodynamic parameter ΔH indicated

an exothermic adsorption process and the negative value of ΔG show the feasibility and

spontaneity of material-anion interaction.

Key words: Defluoridation, fluoride, Groundnut Shell (GS)

Cite this Article: Buddharatna Godboley and Prashant Nagarnaik, Groundnut Shell: Effective

Adsorbent for Defluoridation from Aqueous Solution. International Journal of Civil Engineering

and Technology, 7(6), 2016, pp.51 – 60.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=6

1. INTRODUCTION

Water is very essential natural resource for growth of life on earth which has considered to be plenty

available. Ground water is one of the major & important sources of drinking water. In developing country

like India more than 90% population is dependent on the ground water. Due to modernization and

industrialization these ground water sources were polluted. F- is one of the very common element present

over the earth crust . This element is most electronegative of all other elements. The high level of fluoride

in drinking water imparts the human health hazards, so it is our prime duty to de-fluoridation the ground

water. Many researches & scientists have done lots of work for defluoridation such as Precipitation,

membrane processes, ion-exchange, and adsorption processes are most studied. Adsorption is one the most

trusted methods for de-fluoridation. Many materials or adsorbents were developed and can be used with

high adsorption capacity. In this present study we have try to a solid waste material for removal of fluoride

from drinking water. It has been found that fluoride has a great affinity with silica, alumina, and %

calcium.

Groundnut Shell: Effective Adsorbent for Defluoridation from Aqueous Solution

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2. MATERIALS AND METHOD

2.1. Adsorbent Collection and P

GS was collected from the local market

by drying in an oven at 1100C for 24 hrs.

well in 75μm mesh size particles

ionized water followed by oven drying for

chemical composition test and the

Figure 1 Raw material and Fine particles after passing

from 75µ size sieve

2.2. Instruments and Apparatus

The morphology of GS powder was study using SEM analyzer.

recorded on a Lab india double beam Spectrometer. The

solutions. Orbital shaking incubator is used to control the temperature and

adsorption experiments. SPANDS method

aqueous solution. Fig.4 shows the adsorbent is amorphous in nature; this is done by X

method.

Figure 3 Chemical composition

: Effective Adsorbent for Defluoridation from Aqueous Solution

http://www.iaeme.com/IJCIET/index.asp 52

MATERIALS AND METHODS

Adsorbent Collection and Preparation

rom the local market having high silica content, washed with

C for 24 hrs. The dried shells were grinded in grinding machine

m mesh size particles. The prepared material was preserved and again it is

oven drying for 24hrs as shown in Figure 1. The prepared material is sent for the

chemical composition test and the outcomes are graphically shown in Figure 3.

Raw material and Fine particles after passing

from 75µ size sieve

Figure 2 SEM analysis for GS

pparatus

rphology of GS powder was study using SEM analyzer. Infrared spectroscop

india double beam Spectrometer. The digital pH meter is used to measure the pH

solutions. Orbital shaking incubator is used to control the temperature and

SPANDS methods can be used for determination of fluoride concentration in

Fig.4 shows the adsorbent is amorphous in nature; this is done by X

omposition Figure 4 XRD analysis on GS showing amorphous

nature

: Effective Adsorbent for Defluoridation from Aqueous Solution

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, washed with de-ionized water followed

in grinding machine and sieved

preserved and again it is washed with de-

1. The prepared material is sent for the

3.

SEM analysis for GS

Infrared spectroscopy of the GS was

meter is used to measure the pH of the

solutions. Orbital shaking incubator is used to control the temperature and orbital shaking for the

s can be used for determination of fluoride concentration in

Fig.4 shows the adsorbent is amorphous in nature; this is done by X-Ray diffraction

nalysis on GS showing amorphous

nature



2.3. Preparation of Adsorbate Solution

Small amount of 0.22g sodium fluoride is measured and is dissolved in 1L doubled distilled water to

prepare stock solution of fluoride. Serial dilution of 100 mg/L fluoride stock solution was done to prepare

the required concentration of fluoride solution.

2.4. Adsorption Experiment and Analysis

Large no of experiment were done for the study of effect of pH, effect of adsorbent dose, kinetics study,

kinematics study, selection of an isotherm, and assessment of thermodynamic parameters. The variation of

pH was like 2, 4, 6,8,10 &12, adsorbent dose variation was like 0.5-5.5 g in 100 ml and particle size is less

than 75μm, contact time (15 min to 1440 min), initial fluoride concentration (0,2,4,6,8,10,14 and 16 mg/L)

and temperature (293,303, and 313K) were assess during the study in a 250 ml conical flasks and 100 ml

of fluoride solution of 10mg/l concentrated is added. The solution was kept in orbital shaking incubator at

150 rpm for 24 hr at 303 ± 1K and then the solids particles were separated through normal filtration

process. With the help of double beam spectrophotometer the concentration of fluoride solution can be

determine. For each experiment value we have conducted experiments for thrice and average values was

reported. The amount of fluoride adsorbed per unit adsorbent can be calculated by using mass balance

concept.

3. RESULTS AND DISCUSSION

3.1. Effect of pH

The effect of pH of the fluoride solution is one of the important factors in the process of adsorption.

Therefore the range of pH between 2 to 14 was observed. The pH was maintained at by adding 0.5N HCl

for acidic zone and 0.1N NaOH for alkali zone in 1000 ml of prepared solution of 10mg/L of fluoride

solution for 24 hrs contact time with a dose of 225 mg/100 ml of GS. Figure 5 shows the influence of pH

on % removal of fluoride. As pH increases an increase in % removal is found but after the optimum pH at

8.6 the curve decreases with increase in pH. The decline in adsorption at higher pH values may be possible

due to plenty of OH- ions causing increased hindrance to diffusion of fluoride ions. From figure 1 it was

observed that the highest fluoride removal is achieved at range of pH 7 to 8. Thus, pH 7 (neutral condition)

gave maximum removal, and it was taken into consideration for further studies.

3.2. Effect of Adsorbent Dose

Experimental study was carried to understand effect of adsorbent doses by varying doses between 0.5 to

5.5 g/L. The pH was maintain at 7, while initial fluoride concentration was fixed at 10 mg/L and contact-

time were kept as 24 hrs. Figure 6 shows the effect of adsorbent dose on the % removal or adsorption of

fluoride. The data shows that an increase in the adsorption takes place with the incremental dose of

adsorbent. As the surface area increase, the removal efficiency also increases with immediate increase in

adsorbent dose, and hence extra active sites were available for the adsorption of solution. It is cleared that

GS gives 91.36 % removal of fluoride ions at the dose at room temperature of 30°C. Further no significant

changes found and hence 4.5g/l dose is selected for further studies.



Figure 5 Effect of pH on fluoride removal Figure 6 Effect of adsorbent dose on fluoride removal

3.3. Effect of Stirring Rate

Experiments were carried out to check the effect of stirring rate by varying speeds from 20 to 200 RPM, at

optimum pH of 7.0 with adsorbent dose of 4.5 g/L and 24 hrs of contact time. A curve is plotted between

stirring rate vs. % removal as shown in Figure 7 From figure it is clear that removal is function of stirring

rate. As stirring rate increases there will be an increase in %removal for a given time. The adsorption is

archived at 90% at 150 rpm. Further there is no significant change with increase in stirring rate, so 150 rpm

is considered for further study.

Figure 7 Effect of stirring rate on fluoride removal

Figure 8 Effect of contact time on fluoride removal

(Initial F-

3.4. Effect of Contact Time

Experiments were conducted to check the effect of contact time on removal of fluoride, by varying it from

15 to 1440 minutes. Considering adsorbent dose of 4.5g/L, pH of 7 and rate of stirring 150 rpm by keeping

temperature 293, 303 and 313K experimental data is collected. A curve is plotted between time vs %

removal as shown in Figure 8. It is clear that initially adsorption takes place very rapidly then afterwards

slowed down gradually until it attained equilibrium. Beyond which there is no significance to increase in

the rate of adsorption. For temperature 293K, the removal percentage of fluoride is very fast and within

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14

% R

em

ov

al

pH

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6

% R

em

ov

al

Dose (gm/L)

0

10

20

30

40

50

60

70

80

90

100

0 40 80 120 160 200 240

% R

em

ov

al

Stirring Rate (RPM)

0

10

20

30

40

50

60

70

80

90

100

100 300 500 700 900 1100 1300 1500

% R

em

ov

al

Time (Min)

293K

303K

313K



360 minute about 90.53% removal is found and there was no significant change in the rate of removal

which denoting accomplishment of equilibrium. However the removal efficiency increases trend usually

from 360 to 240 min in case of 303K and 240 minute to 120 minute in case of 313K. Further increase in

contact time does not increase % removal, because there is a deposition of fluoride ions on the available

adsorption sites on adsorbent material. Therefore equilibrium time of 240 minute is selected for the study

at room temperature.

3.5. Effect of Initial Concentration and Temperature of Fluoride

Experimental were carried out to check the effect of initial concentration fluoride by varying initial

concentration from 2,4,6,8,10,12,14 and 16 mg/L at different temperatures (293, 303 and 313K ) at

adsorbent dose of 4.5g/L, stirring rate of 150 rpm pH of 7, and contact time of 240 minutes. Experimental

data is collected and a curve is plotted between initial concentration vs % removal as shown in Figure 9

and Figure 10. As initial concentration increases there is decline in the removal percentage of fluoride ion.

Also as temperature increases there is an increased mobility of the adsorbate and a decrease in the retard

force action on the diffusing adsorbate. Moreover as temperature increases there will be increase in active

sites of the adsorbents.

Figure 9 Effect of Initial concentration of F- Figure 10 Effect of Temperature

3.6. Adsorption Isotherms

Study on equilibrium was carried out pH at 7.0 for adsorption onto the GS and temperatures of 293,303, &

313K, as shown in Figure 11 to 12. Results clears that the GS has an affinity for fluoride adsorption under

these conditions. The equilibrium study includes isotherm model equations, viz. Langmuir (Fig. 11),

Freundlich (Figure 12), and Temkin (Figure 13). The value of slope & intercept provides the related

parameters. Table 1 shows the linear plots of equilibrium models. The figure and table shows that

Langmuir well fitted curve (R2 > 0.9972). The average monolayer adsorption capacity (qm) obtained for

GS is 1.451 mg/g. The Freundlich isotherm model is based on multilayer adsorption, and data represent

that it is fairly fitted (R2 = 0.899, 0.970 & 0.989 for 293K, 303K & 313K respectively). From the linear

plot Freundlich adsorption constants (KF) were obtained 0.944, 1.390, & 1.653 for 293K, 303K & 313K

respectively. The Freundlich coefficient (n), having values ranging from 3.537 to 7.706. A very simple

form of adsorption model is developed considering the chemisorptions of an adsorbate onto the adsorbent

(R2 = 0.945, 0.978, 0.986). A well fitted curve shows that the adsorption process is might be going on onto

the adsorbent due to chemisorptions with physical forces. Hence, the order of isotherm equations obeyed

by the present data is Langmuir > Temkin > Freundlich isotherm.

A relationship between RL and Co was obtained and shown in Figure 14. It shows the necessary

features of the Langmuir isotherm. RL values for GS at different temperatures are represented in Table

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16

% R

em

ov

al

Initial Concentration (mg/L)

293K

303K

313K

0

10

20

30

40

50

60

70

80

90

100

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

% R

em

ov

al

Dose (gm/L)

293K

303K

313K



2.for the present study , the values of RL for fluoride concentration are found to be in the range of 0.012–

0.323, which suggests the good adsorption of fluoride onto the adsorbent, under the experimental

conditions.

Figure 11 Langmuir isotherms using GS at various

temperatures.

Figure 12 Plot of the Freundlich isotherm for fluoride

adsorption on GS

Figure 13 Adsorbent response to Temkin isotherm Figure 14 Separation factor RL values verses initial

fluoride concentration

Table 1 Isotherm parameters obtained for the adsorption of fluoride onto GS

Models Parameters 293K 303K 313K

Langmuir Isotherm

R2 0.964 0.997 0.999

qm (mg/g) 0.932 1.564 1.855

Kl (L/mg) 2.094 4.202 6.773

Freundlich Isotherm

Kf (L/mg) 0.944 1.390 1.653

n 3.537 6.246 7.067

1/n 0.283 0.160 0.142

R2 0.899 0.970 0.989

Temkin Isotherm

b 6061.214 8388.751 8515.321

Kt (L/mg) 76.261 702.828 1822.319

B 0.402 0.300 0.306

R2 0.945 0.978 0.986

R² = 0.9639

R² = 0.9972

R² = 0.99910

1

2

3

4

5

6

7

0.00 2.00 4.00 6.00

Ce

/qe

(g

/L)

Ce (mg/L)

293K

303K

313K

R² = 0.8978

R² = 0.9727

R² = 0.9841

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

-1.00 -0.50 0.00 0.50 1.00 1.50 2.00

Ln(q

e)

Ln(Ce)

293K

303K

313K

R² = 0.9452

R² = 0.9781

R² = 0.9855

0.00

0.50

1.00

1.50

2.00

2.50

-1.00 -0.50 0.00 0.50 1.00 1.50 2.00

qe

Ln(Ce)

293K

303K

313K

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0 2 4 6 8 10 12 14

RL

C0

293k

303k

313k



3.7. Thermodynamic Parameters

The temperature effect is a biggest factor for controlling the sorption process and therefore the sorption of

GS was monitor at three different temperatures 293, 303, and 313K. Standard enthalpy change (ΔHº)

standard free energy change (ΔGº), and standard entropy change (ΔSº) are the thermodynamic parameters,

Theses parameters were calculated & presented in Table 3 and graphical representation shown in Fig. 15.

If values of ΔGº are negative then it indicates that sorption reaction is spontaneity. If the value of ΔHº

comes negative then it indicates the exothermic nature of the sorption process (Srivistav et.al, 2006).

Suppose the value of ΔSº comes positive then it shows the increasing randomness at the solid/liquid

interface during sorption of fluoride. The study shows as temperature increases, adsorption capacity also

increase. This is most probably due to control of the adsorption process by diffusion phenomenon.

Therefore, reaction is endothermic in nature of the diffusion controlled adsorption process.

Figure 15 Vant-off Plot for Thermodynamics

Table 2 Values of RL at different temperatures, calculated using Langmuir constants.

C0 (mg/L) RL

293 303 313

1 0.323 0.192 0.129

2 0.193 0.106 0.069

4 0.107 0.056 0.036

6 0.074 0.038 0.024

10 0.046 0.023 0.015

12 0.038 0.019 0.012

Table 3 Thermodynamic parameters of fluoride sorption on GS

ΔG (kJ/mol) ΔH (kJ/mol)

ΔS

(kJ/mol K) 293K 303K 313K

-1.8007 -3.616 -4.978 -44.812 0.159

3.8. Adsorption Kinetics

Several kinetics models have been applied to express the mechanism of solute sorption onto a sorbent. In

this present study pseudo first & second order, inter-particle diffusion model, Elovich and Modified

Freundlich has been used to investigate the adsorption process of fluoride on SS. The time dependent

adsorption data shown in Fig.16-19 have been analysed using the linear form of kinetics equations.

Considering initial concentration of 10mg/L, kinetics study on adsorption had been studied at 293k, 303k

R² = 0.9922

0

0.5

1

1.5

2

2.5

0.00315 0.0032 0.00325 0.0033 0.00335 0.0034 0.00345

ln(K

)

1/T (/k)



& 313k and pH 7.0 for the kinetic study pseudo second-order reaction rate model, Elovich equation model

and intra-particle diffusion fit well.

The pseudo second-order reaction rate model is plotted between times vs. log (qe-qt) as shown in

Figure 20 shows. The model described the kinetics of sorption with high value of R2, ranges between 0.992

- 0.997. The calculated equilibrium capacities (qe) fit well the experimental data. The adsorption

mechanism was predominant and that the overall rate of the fluoride adsorption process appeared to be

controlled by chemical process (Gupta, 1998; Ajmal et al., 2003). The sorption process may possibly be

ion-exchange in nature where the fluoride molecules attach with the various negatively charged inorganic

functional groups present on the surface of the GS.

The Elovich equation model is plot between ln(t) vs qt as shown in figure 19. This model describes

chemisorptions on highly heterogeneous adsorbents, which give a good account of adsorption of fluoride

with R2 value ranges 0.944- 0.812.

Intra-particle diffusion model is linearly plot between qt versus t0.5

with regression coefficient R2 of

0.767-0.527, but the line did not pass through the origin, indicating that this model did not fit the

adsorption process (McKay and Poots, 1980).

Modified Freundlich Model is plot of ln(qt) vs ln(t) .The value of parameters like k and m are used

empirically to evaluate the effect of surface loading and ionic strength on the adsorption process which is

determined by the intercept and slope (Onoal, 2006). It has been seen that the R2 value decreases with

increase in temperature and is ranges from 0.942-0.871. In Table 3 it has been seen that the order of model

is obeyed by the present data is Pseudo Second Order Model > Elovich Model > Modified Freundlich

Model > Intra-particle Diffusion Model > Pseudo First Order Model.

Figure 16 Pseudo first order model Figure 17 Pseudo second order model

Figure 18 Intra particle diffusion model Figure 19 Elovich model for adsorption

R² = 0.3729

R² = 0.4318

R² = 0.3317

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0 500 1000 1500 2000

log

(qe-

qt)

Time (Min)

293K

303K

313K

R² = 0.992

R² = 0.9952

R² = 0.9973

-2000

0

2000

4000

6000

8000

10000

12000

0 500 1000 1500 2000

t/q

t

Time (Min)

293K

303K

313K

R² = 0.7669

R² = 0.672

R² = 0.5341

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.000 1.000 2.000 3.000 4.000 5.000 6.000

qt

(mg

/g)

t^(0.5)

293K

303K

313K

R² = 0.9444

R² = 0.8885

R² = 0.7721

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.00 2.00 4.00 6.00 8.00

qt

ln(t)

293K

303K

313K



Table 4 Kinetics parameters for the removal of fluoride onto GS

Models Parameters 293K 303K 313K

Pseudo First order model

qe (mg/g) 2500 10000 12500

Kf (per min) -9.21E-04 -2.03E-04 -1.84E-04

R2 0.373 0.449 0.358

Pseudo Second-order model

qe(mg/g) 0.126 0.145 0.165

Ks (g/mg min) 0.108 0.147 0.202

h (mg/g/min) 0.002 0.003 0.006

R2 0.992 0.995 0.997

Intra-particle diffusion model

Ki1 (mg/g min1/2) -0.206 -0.087 -0.064

C1 0.916 0.479 0.408

R2 0.767 0.695 0.572

Elovich model

B -4.000 -10.173 -13.245

α (mg/g per min) -0.166 -0.091 -0.072

R2 0.944 0.907 0.812

Modified Freundlich Equation

M 1.840 3.097 3.935

k (L/g/min) 1.189 0.967 1.009

R2 0.942 0.942 0.871

Figure 20 Modified Freundlich model for adsorption of fluoride on to GS

4. CONCLUSION

From the batch study it is clear that GS had comparatively good potential for the removal of fluoride from

aqueous solution. The equilibrium study indicates that Langmuir isotherm model is most fitted curve, as

compare to Freundlich and Temkin isotherms. Maximum monolayer sorption capacity was 1.564 mg g-1 at

303 K which indicating monolayer sorption on a homogenous surface. The RL values showed that GS was

favourable for the adsorption of fluoride. It was very clear that the adsorption kinetics of fluoride to GS

obeyed pseudo-second-order, Elovich model and Modified Freundlich equation adsorption kinetics. The

adsorption kinetics process is chemisorptions this is because pseudo-second-order kinetic model indicating

shows the best fitting curve. Thermodynamic parameters showed that adsorption of fluoride on GS were

exothermic and spontaneous in nature.

R² = 0.9419

R² = 0.9276

R² = 0.8381-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0.50

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00

Ln

(qt)

Ln(t)

293K

303K

313K



REFERENCE

[1] B.J.Godboley, P.B.Nagarnaik, Exposure of Fluoride Contamination to Ground Water and Removal by

Adsorption Method: A Review, Journal of Indian Water Works Association (JIWWA), Vol. XXXXV

No.4 October-December 2013, Vol. XXXXVI No. 1 January-March 2014,pp 304-309

[2] Gupta VK (1998). Equilibrium uptake, sorption dynamics, process development, and column operations

for the removal of copper and nickel from aqueous solution and wastewater using activated slag, a low-

cost adsorbent, Ind. Eng. Chem. Res. 37: 192–202.

[3] K. Yadav, C. P. Kaushik, A. K. Haritash, A. Kansal and Neetu Rani, Defluoridation of Groundwater

Using Brick as an Adsorbent, J. Hazardous Materials (2005)

[4] Leo Spira and F. H. Grimbleby, ”The Journal of Hygienee”, Vol. 43, No. 2 (Apr., 1943), pp. 142-145

[5] McKay G, Poots VJP (1980). Kinetics and diffusion processes in colour removal from effluent using

wood as an adsorbent. J. Chem. Tech Biotechnol. 30(1): 279–292.

[6] Onal Y, Kinetics of adsorption of dyes from aqueous solutions using activated carbon prepared from

waste apricot.J Hazard mater B137, 1719-1728, 2006

[7] Pali Shahjee, B.J.Godboley, removal of fluoride from aqueous solution by using low cost adsorbent,

International Journal of Innovative Research in Science, Engineering and Technology, Vol. 2, Issue 7,

July 2013

[8] Shrivastava,V.C, Mall, I D, Mishra, Characterization of mesoporous rice husk(RHA) and adsorption

kinetics of metals ions from aqueous solutions onto (RHA, J hazard matter B137, 256-257, 2006

[9] Yu. V. Ermolovv, “Contemporary Problems of Ecology”, 2009, Volume 2, Number 2, pp 16

[10] Raman Kumar and Ankit, An Experimental Study of Marble Powder on The Performance of Concrete.

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[11] Adarsh Minhas and Veena Uma Devi, Soil Stabilization of Alluvial Soil by using Marble Powder.

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