removal of toxic metal hexavalent chromium …...nanoscale zerovalent iron as adsorbent :...

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 2, No 4, 2012

© Copyright 2010 All rights reserved Integrated Publishing Association

Research article ISSN 0976 – 4402

Received on March 2012 Published on May 2012 1962

Removal of toxic metal Hexavalent Chromium [cr(vi)] from aqueous

solution using starch – stabilized nanoscale zerovalent iron as adsorbent :

Equilibrium and kinetics Selvarani. M

1, Prema. P

2

1- Research Scholar, Post Graduate and Research Department of Zoology,

V. H. N. S. N. College, Virudhunagar - 626 001, Tamil Nadu, India

2- Assistant Professor in Zoology, Post Graduate and Research Department of Zoology,

V. H. N. S. N. College, Virudhunagar - 626 001, Tamil Nadu, India

[email protected]

doi:10.6088/ijes.00202030080

ABSTRACT

Groundwater remediation by nanoparticles has received increasing interests in recent years.

The present work was conducted to investigate the feasibility of using new class of stabilized

zerovalent iron (ZVI) nanoparticles for In situ reductive immobilization of Cr(VI) in water.

The nanoparticles were prepared by chemical reduction method using Ferrous sulfate

heptahydrate (FeSO4.7H2O) with sodium borohydride (NaBH4) as a reducer. This sample

was subjected to XRD for the determination of crystallinity and average particle size. The

size of the particle is 12.4 nm. The morphology of the nanoparticles was observed using

SEM. Batch experiments reported that the synthesized starch stabilized zerovalent iron

nanoparticles were able to rapidly reduce Cr(VI) in aqueous solution. The extend of Cr(VI)

reduction was increased with increasing concentration of iron nanoparticles (0.1 g/L – 0.4

g/L) and inversely with initial Cr(VI) concentration (10 mg/L – 25 mg/L) as well as with

decreasing pH (3 – 10). The equilibrium data obtained from the experimental results were

then fitted to the Freundlich and Langmuir isotherm models. Kinetic models were examined

with pseudo first order rate reaction. The Correlation coefficient between experimental

parameters and time shows that there is a strong positive correlation for Cr(VI) reduction.

This study indicates that the zerovalent iron nanoparticles, especially those which were

starch-stabilized can yield a high removal efficiency in the reduction of Cr(VI) contaminated

groundwater.

Keywords: Starch Stabilized Feo, XRD, SEM, Cr(VI) transformation.

1. Introduction

With the advancement of industrialization, agricultural and urban activities, the levels of

groundwater contamination have increased many folds in the last few decades. The

increasing contamination of groundwater by toxic metal ions is a significant environmental

hazard to drinking water supplies. Chromium (Cr), which is one of the most toxic and

important heavy metals commonly found in wastewater from industrial activities mainly

through tanning and electroplating industries (Sayari et al., 2005). In the United States, it is

the second most common inorganic contaminant in water after lead. Chromium, essentially

exists in two oxidation forms namely Cr(III) and Cr(VI). Over a narrow concentration range,

Cr(III) is proved to be biologically essential to mammals as it maintains an effective glucose,

lipid and protein metabolism, whereas Cr(VI) is reported to have toxic effect on humans and

it is considered to be genotoxic and carcinogenic in nature (Cheuhan and

Removal of toxic metal Hexavalent Chromium [cr(vi)] from aqueous solution using starch – stabilized

nanoscale zerovalent iron as adsorbent : Equilibrium and kinetics

Selvarani. M, Prema. P

International Journal of Environmental Sciences Volume 2 No.4, 2012 1963

Sankararamakrishnan, 2011). Major toxic effects of Cr(VI) are chronic ulcer, dermatitis,

corrosive reaction in nasal septum and local effects in lungs. Therefore, the hexavalent form

of Cr has been considered to be more hazardous due to its carcinogenic properties (Kobya,

2004). The permissible limit of Cr(VI) in industrial effluents is set at 0.5 mg/L by the

Ministry of Environment and Forests (MoEF), by Government of India (Panda et al., 2011).

The high toxicity of Cr(VI) is related to its ability to cross the cell membrane and its strong

oxidation properties (Girard and Hupert, 1996). As a result, removing Cr(VI) from industrial

wastewater has become necessary in order to avoid contamination of natural and raw water

used for public supply. Much research has focused on the remediation of Cr(VI) and many

treatment processes have been developed. Environmental chemists and material scientists

have always focused their attention on the development of cost-effective adsorbents which

could be exploited for the effective removal of Cr(VI) from aqueous solution. Recently,

nanomaterials have received considerable attention due to their small particle size, large and

controllable surface area, cost-economy, non-toxicity and ease of preparation. Reduction of

Cr(VI) to Cr(III) by powder or granular zerovalent iron (Feo) particles and non-stabilized or

agglomerated ZVI nanoparticles have been investigated in a number of laboratory and field

studies. Cr(VI) reduction by Feo appears to be one of the most promising chemical

technologies. Powell et al. (1995) suggested that the mechanism of Feo is a cyclic, multiple

step electrochemical corrosion process and confirmed that aluminosilicate minerals could

enhance the rate of Cr(VI) reduction. Cr(VI) removal capacity highly depended on reaction

time, solution pH, temperature, initial Cr(VI) concentration and material dosage (Shen et al.,

2012).

Feo nanoparticels, due to their extremely high surface areas, can enchance the reduction

efficiencies remarkably. Typically, Feo nanoparticles are prepared by reducing Fe(II) or

Fe(III) in an aqueous solution using a strong reducing agent (NaBH4) appears most suitable

because of its minimal use of environmentally harmful solvents and chemicals. However,

because of their high surface area and high reactivity ZVI nanoparticles prepared using

traditional methods tend to either agglomerate rapidly or react quickly with the surrounding

media (eg: dissolved oxygen or water) resulting in rapid loss in soil mobility as well as

reactivity (He and Zhao, 2005). Because agglomerated ZVI nanoparticles are often in the

range of micron scale therefore they are not transportable or deliverable in soils. To prevent

particles from agglomeration, researchers have been trying to prepare more stable and

chemically more reactive Fe(0) nanoparticles using a dispersion as stabilizer. In this work, a

new class of Feo based nanoparticles using water-soluble starch as dispersant prepared by

borohydride reduction method, which were tested for their ability to reduce toxic hexavalent

chromium [Cr(VI)] ions form aqueous solution. Also, the influence of Cr(VI) and

nanoparticles concentration, variation in pH and temperature of solution on the efficacy of

Cr(VI) removal was evaluated. The experimental data were analyzed by fitting it into

Langmuir and Freundlich isotherm and pseudo first order kinetic models.

2. Materials and method

2.1 Materials

Ferrous sulfate heptahydrate (FeSO4.7H2O), Sodium borohydride (NaBH4), Starch and

Ethanol were purchased from Himedia (P) Ltd, Mumbai were used as starting materials

without further purification. Potassium dichromate (K2Cr2O7) was used as a model

contaminant. Milli-Q water was used throughout the experiment.





2.2 Methods

Preparation of starch-stabilized zerovalent iron nanoparticles

The preparation of starch-stabilized Fe0

nanoparticles was followed the methods described by

He and Zhao (2005). Starch serves as a stabilizer and dispersant that prevents the resultant

nanoparticles from agglomeration, thereby prolonging their reactivity and maintaining the

physical integrity. In brief, the preparation was carried out in a 250 ml conical flask attached

to a vacuum line. Before use, deionized (DI) water and the starch solution were purged with

purified N2 gas for 15 min to remove dissolved oxygen (DO). In a typical preparation, a

stock solution of 0.21 M FeSO4.7H2O was prepared right before use and then was added to

the starch solution through burette to yield the desired concentration of Fe and starch. Fe

concentration used in this study was 0.1 g L-1

and the corresponding starch concentration was

0.2% (w/v).

The Fe2+

ions were then reduced to Fe0 by adding a stoichiometric amount of NaBH4 aqueous

solution at a BH4-/Fe

2+ molar ratio of 2.0 to the mixture with magnetic stirring at 230 rpm

under ambient temperature. The ferrous iron was reduced to zero-valent iron according to the

following reaction:

Fe(H2O)62+

+2BH4−→Fe

0↓+2B(OH)3+7H2↑

The resultant black particles were separated from the solution by centrifugation at 4000 rpm

for 5 min and washed with N2 saturated deionized water and at least three times with

99% absolute ethanol. Finally, the synthesized starch stabilized Feo nanoparticles were dried

in an oven at 60oC.

2.3 Characterization of Synthesized Starch-Stabilized Fe0 Nanoparticles

2.3.1 X-ray Diffraction

The crystallographic analysis of the sample was performed by powder X-ray diffraction. The

X-ray diffraction patterns of synthesized starch-stabilized Fe0 nanoparticles were recorded

with an X‟pert PROPAN analytical instrument operated at 40 kV and a current of 30 mA

with Cu α radiation (λ=1.54060 Ao). A continuous scan mode was used to collect 2θ data

from 10.08o

to 79.93o. The diffraction intensities were compared with the standard JCPDS

files (No: 80 – 2186). Crystalline size of the nanoparticles was calculated from the line

broadening of X-ray diffraction peak according to the Debye-Scherer formula (Huang and

Tang, 2005).

D = kλ/ β Cosθ,

Where D is the thickness of the nanocrystal, „k‟ constant, „λ‟ wavelength of X-rays, „β‟ width

at half maxima of reflection at Bragg‟s angle 2θ, „θ‟ Bragg‟s angle.

2.3.2 Scanning Electron Microscopy

Surface morphology and the size distribution of the particles was investigated with the

Scanning Electron Microscope (SU 1510) operated at 15kV, magnification x350. The solid

samples were sprinkled on the adhesive carbon tape which is supported on a metallic disk.

The sample surface images were taken at different magnifications. The scale was about

100 µm which is equivalent to 57 mm for the synthesized starch-stabilized Fe0 nanoparticles.





2.4 Cr(VI) reduction studies

2.4.1 Preparation of Cr(VI) solution

Stock solution (1000 mg/L) of Cr(VI) was prepared by dissolving 2.829 g of K2Cr2O7 in

1000 ml of double distilled water. Experimental solutions of the desired concentrations were

obtained by successive dilutions and Cr(VI) was determined via 1,5-diphenylcarbazide

(DPC) colorimetric method by measuring the absorbance at a wavelength of 540 nm using

UV-Vis spectrophotometer. 0.1M NaOH or HCl was used for the adjustment of pH and

controlled by pH meter.

2.4.2 Batch experiments

The batch experiments for the reduction of Cr(VI) was performed in 250ml Erlenmeyer

flasks into which synthesized starch stabilized Feo nanoparticles were introduced, followed

by the addition of Cr2O72-

aqueous solution. The reaction solution was stirred at a speed of

500 rpm and periodically sampled by glass syringe. The samples were filtered immediately

through 0.2µm membrane filters and analyzed for Cr(VI). The absorbance of purple Cr(VI)-

diphenylcarbazide product developed after 10 min was measured at a wavelength of 540 nm

using UV-Vis spectrophotometer.

The effect of various parameters on the Cr(VI) reduction was studied. Starch stabilized Feo

nanoparticles concentration used in this study was 0.1 g to 0.4 g/L. The initial Cr(VI)

concentration was 10 mg to 25 mg/L, the initial pH was 3 to 10 and the initial temperature

was 15oC to 45

oC.

2.4.3 Reduction of Cr(VI) by starch stabilized Feo nanoparticles

According to Sethuraman and Balasubramanian (2010), the percentage of Cr(VI) removal

was calculated spectrophotometrically using the formula

Removal of Cr(VI)%

Where, Co and Ce represent initial and final concentration of Cr(VI).

The initial reduction rate of Cr(VI) can be described by pseudo first order reaction kinetics

expression (Ponder et al., 2000 and Liu et al., 2008).

The equilibrium adsorption capacity of Cr(VI) was calculated by

qe = (Co – Ce) X V/M

Where qe (mg/g) is equilibrium adsorption capacity, Co and Ce are initial and equilibrium

concentration (mg/L) of Cr(VI) respectively, V (L) is the volume of solution and M (g) is the

weight of the adsorbent.





3. Results and discussion

3.1 X-ray diffraction

The X-ray diffraction pattern shows that the synthesized starch-stabilized Feo

nanoparticles

are in amorphous stage and in tetragonal system. In the respective nanoparticles, the

intensive diffraction peaks were observed at a 2θ value of 44.94o from the lattice plane (311)

of face-centered cubic (fcc) Fe unequivocally indicates that the particles are made of pure

iron (Figure 1). Alidokht et al. (2011) reported that characteristic peak at 2θ value of 44.7o

indicates the crystalline nature of Feo nanoparticles. In the obtained spectrum, the Bragg‟s

peak position and their intensities were compared with the standard JCPDS files. The size of

the particles was found to be 12.4 nm.

Position [°2Theta]

20 30 40 50 60 70

Counts

0

100

200

A Fe

Figure 1: X-ray Diffraction Spectrum of Synthesized Starch Stabilized

Zero-Valent Iron Nanoparticles

3.2 Scanning Electron Microscopy

The scanning electron microscopy of synthesized starch-stabilized Fe0 nanoparticles shows

that the particles are hexagonal and spherical in nature (Figure 2).

Figure 2: Scanning Electron Mircograph of Synthesized Starch Stabilized

Zero-Valent Iron Nanoparticles

(311)





The micrograph shows that the synthesized particles did not appear as discrete particles but

form much larger dendritic flocs. The aggregation is due to the vandar waals forces and

magnetic interactions among the particles. This finding is very much closer to the earliest

report (Rahmani et al., 2011).

3.3 Cr(VI) reduction studies

3.3.1 Effect of initial Cr(VI) concentration on Cr(VI) reduction

The removal efficiency is defined as the fraction of Cr(VI) in the solution during the reaction

rate as a fraction of the initial concentration. To investigate the effect of initial Cr(VI)

concentration, the batch experiments were conducted at various concentration of Cr(VI) from

10 to 25 mg/L. Figure 3 explains that the removal efficiency increased inversely with the

initial Cr(VI) concentration.

Figure 3: Effect of initial Cr(VI) concentration on Cr(VI) removal efficiency by

Starch - stabilized Feo nanoparticles

The removal efficiency of Cr(VI) decreased from 96% to 63.6% with increasing the initial

Cr(VI) concentration. Similarly, the rate constant of Cr(VI) removal is decreased with

increasing initial Cr(VI) concentration. The decrease in the percentage removal of Cr(VI)

can be explained with the fact that the Feo nanoparticles had a limited active sites, which

would have become saturated above a certain circumstances (Kalpan and Gilmore, 2004).

kobs was obtained by plotting linear regression of ln normalized concentration of Cr(VI) vs

time. The kobs is ranging from 111 ± 7.5 x 10-3

min-1

to 46 ± 2.7 x 10-3

min-1

with increasing

initial Cr(VI) concentration (Table 1).

Table 1: Effect of initial Cr(VI) concentration on Cr(VI) reduction rate constants and half

lives for starch-stabilized Feo nanoparticles

Initial conc. of Cr(VI)

(mg/L)

kobs (min-1

) t1/2 obs (min) r2

10 111.0 ± 7.5 x 10-3

6.31 ± 0.42 0.986

15 38.0 ± 4.0 x 10-3

18.21 ± 1.70 0.995

20 46.0 ± 4.0 x 10-3

15.30 ± 1.46 0.982

25 46.0 ± 2.7 x 10-3

15.12 ± 0.91 0.984

Experimental Conditions: Conc. of Feo = 0.2 g/L, Temp = 28

oC, pH = 7, ω = 500 rpm.





In this study, it is also found that reduction of Cr(VI) is proceeded in two steps. During the

first few min of the experiment, decrease of Cr(VI) is much dramatic and the reaction can be

expressed with a pseudo-first-order kinetics. This indicates that the predominant mechanism

for the removal of Cr(VI) is most likely due to the adsorption to the Feo nanoparticles surface

rather than the reductive transformation (Geng et al., 2009). The reductions of Cr(VI) in other

Feo nanoparticles system have been reported as pseudo-first-order (Ponder et al., 2000; Xu

and Zhao, 2007). The two-step kinetics have been explained as reduction of Cr(VI) under the

existence of Feo followed by a faster physical or a chemical adsorptions (Deng et al., 1999;

Ponder et al., 2000; Kanel et al., 2005).

3.3.2 Effect of adsorbent concentration on Cr(VI) reduction

The effect of adsorbent concentration on the adsorption of Cr(VI) ions in aqueous solution

was examined by varying the adsorbent concentration from 0.1 g/L to 0.4 g/L is given in

Figure 4.

Figure 4: Effect of initial Fe

o concentration on Cr(VI) removal efficiency by


Removal efficiency increased from 31% to 95.5% with increasing concentration of adsorbent

dosage. Increase in adsorbent concentration generally increases the level of adsorption of

Cr(VI) ions because of an overall increase in surface of the adsorbent which in turn increase

the number of binding sites lead to the increase of Cr(VI) removal efficiency (Esposito et al.,

2001). It is believed that reduction reaction occurs on the iron surface. Similar findings have

also been reported by Lai keith (2008). The pseudo first order rate constants are summarized

in Table 2.

The results indicated that the rate constant value rose from 9.7 ± 2.5 x 10-3

min-1

to

74 ± 4 x 10-3

min-1

when the Feo nanoparticles dosage was increased from 0.1 to 0.4 g/L. It

was reported that kobs are strongly dependent on the amount of Feo nanoparticles used and

linear variations of kobs with Feo

dose was observed for heterogeneous reactions for the

reduction of numerous contaminant by Feo (Ponder et al., 2000; Alowitz and Scherer, 2002).





Table 2: Effect of initial Feo concentration on Cr(VI) reduction rate constants and half lives

for starch-stabilized Feo nanoparticles

Initial conc. of Feo

(g/L)

kobs (min-1

) t1/2 obs (min) r2

0.1 9.7 ± 2.5 x 10-3

78.30 ± 27.25 0.993

0.2 46.0 ± 4.0 x 10-3

15.30 ± 1.46 0.982

0.3 57.0 ± 3.0 x 10-3

12.19 ± 0.63 0.994

0.4 74.0 ± 4.0 x 10-3

9.42 ± 0.52 0.996

Experimental Conditions: Conc. of (VI) = 20mg/L, Temp = 28 oC, pH = 7, ω = 500 rpm.

3.3.3 Effect of initial pH on Cr(VI) reduction

The influence of pH on Cr(VI) removal efficiency was studied by changing the initial pH

from 3 to 10. The relation between the initial pH of the solution and the percentage removal

efficiency of Cr(VI) is shown in Figure 5.

Figure 5: Effect of initial pH on Cr(VI) removal efficiency by


The removal efficiency increased significantly with decreasing pH. The percentage of Cr(VI)

decreased from 97% to 28.5% with increasing the initial pH. Under acidic condition, the

removal efficiency was rapid would accelerate the corrosion of Feo, thus enhancing Cr(VI)

reduction. It indicated that the Feo nanoparticles have a high reactivity at pH below 5. In

contrast, the plots for pH>8 show less rapid removal. This may be because of the formation

of mixed Fe and Cr oxyhydroxides at high pH values on the iron surfaces (Powell et al.,

1995; Lee et al., 2003). A decrease in kobs is noticed from 62 ± 11 x 10-3

min-1

at pH 3 to

16 ± 1.4 x 10-3

min-1

at pH 10 (Table 3).

Table 3: Effect of initial pH on Cr(VI) reduction rate constants and half lives for starch-

stabilized Feo nanoparticles

Initial pH kobs (min-1

) t1/2 obs (min) r2

3 62.0 ± 11.0 x 10-3

11.43 ± 1.93 0.984

5 39.0 ± 3.2 x 10-3

14.89 ± 1.47 0.989

8 26.0 ± 1.7 x 10-3

27.08 ± 1.80 0.992

10 16.0 ± 1.4 x 10-3

43.26 ± 3.65 0.979

Experimental Conditions: Conc. of (VI) = 20mg/L, Conc. of Feo = 0.2 g/L,

Per

cen

tag

e R

emo

val

eff

icie

ncy

of

[Cr(

VI)

]





Temp = 28 oC, ω = 500 rpm.

It shows that there is a dramatic change in the rate constant between the pH values. These

results demonstrate that the acidic conditions would accelerate the corrosion of Feo, thus

enhancing Cr(VI) reduction. Under certain circumstances, Feo donates the electrons either to

protons or to chromate anions and itself will be oxidized to Fe(III). The protons will be

reduced to hydrogen gas which in turn reduces Cr(VI) to cr(III) (Melitas et al., 2001). The

decrease in adsorption of Cr(VI) by increasing the pH is due to the competition between the

anions CrO42-

and OH- (Ponder et al., 2000).

3.3.4 Effect of temperature on Cr(VI) reduction

The relation between the temperature and Cr(VI) removal efficiency is depicted in Figure 6.

Figure 6: Effect of initial temperature on Cr(VI) removal efficiency by


It is noticed that as the temperature increases, the removal efficiency also increases. The

removal efficiency increased from 32.5% to 72% with increasing the initial temperature

from 15oC to 45

oC. The rate constant value (kobs) increased as the temperature increases

(Table 4), indicating that vibration rate of Cr(VI) increases at high temperature. Similar

findings have been reported by earlier studies (Wang et al., 2010).

Table 4: Effect of initial temperature on Cr(VI) reduction rate constants and half lives for

starch-stabilized Feo nanoparticles

Initial temp

(oC)

kobs (min-1

) t1/2 obs (min) r2

15 13.0 ± 2.0 x 10-3

55.36 ± 9.34 0.989

25 17.0 ± 2.0 x 10-3

41.0 ± 4.59 0.990

35 26.0 ± 2.0 x 10-3

27.05 ± 3.52 0.995

45 76.0 ± 6.0 x 10-3

9.19 ± 0.82 0.989

Time (min)





Experimental Conditions: Conc. of (VI) = 20mg/L, Conc. of Feo = 0.2 g/L,

pH = 7, ω = 500 rpm.

Adsorption isotherms

To study the adsorption efficiency of Cr(VI) at the surface of the adsorbent, an attempt was

made to test for the Langmuir and Freundlich isotherm models on the obtained experimental

data.

Freundlich isotherm

The mathematical expression for the non-linear form of the Freundlich isotherm model

(Choy et al., 1999) can be given as

qe = KfCe1/n

This equation is frequently used in the linear form by taking the logarithm of both sides

log qe = log Kf + Ce

A plot of log qe versus log Ce gives a straight line (Figure 7).

0.2 0.4 0.6 0.8 1.0

1.6

1.8

2.0

2.2

2.4

Lo

g q

e

Log ce

Figure 7: Freundlich isotherm model for Cr(VI) adsorption by


Kf and n are the isotherm constants. The values of Kf and n along with the linear regression

co-efficient (r2) for the present experimental data have been obtained and are shown in

Table 5.

Langmuir isotherm

The non-linear form of the Langmuir isotherm model for monolayer adsorption is expressed

by equation (Gupta and Babu, 2009).

The equation can be rearranged the following linear form





The binding constant (qm) and the adsorbent capacity (Kq) are estimated by plotting Ce/qe

against Ce (Figure 8).

0.2 0.4 0.6 0.8

0.2

0.3

0.4

0.5

0.6

0.7

c e / q

e

ce

Figure 8: Langmuir isotherm model for Cr(VI) adsorption by


The experimental values of qm and Kq along with the linear regression co-efficient (r2) are

given in Table 5. The comparison of correlation coefficients (r2) indicates that both the

adsorption isotherm models match satisfactorily with the experimental data obtained from the

present study.

Table 5: Adsorption isotherm constants for Cr(VI) reduction by Starch-stabilized Feo

nanoparticles

Langmuir constants Freundlich constants

Qm Ka R2

Kf n R2

0.544 0.181 0.999 0.999 1.398 1.0

4. Conclusion

In this study, starch stabilized Feo nanoparticles has been successfully prepared by chemical

reduction method and its removal efficiency was evaluated using potassium dichromate

(K2Cr2O) as a model contaminant. The results obtained from the experimental conditions

support the conclusion that the concentration of starch stabilized Feo nanoparticles had

significant effect on the reduction rate of Cr(VI). The pH of the reaction mixture has a strong

effect on the Cr(VI) reduction efficiency with increasing initial pH as well as with decreasing

initial Cr(VI) concentration . The reduction rate is expressed by pseudo first order reaction

rate equation. Equilibrium data fitted well with both Langmuir and Freundlich adsorption

isotherm models. Thus the results from the current research provides compelling evidence

that the starch –stabilized Feo nanoparticles may be used for in situ reductive efficacy of

Cr(VI) contaminated water and soils, which may lead to an innovative remediation

technology is likely to be more cost effective and less environmentally disruptive.

Acknowledgement

The authors are very grateful for the financial support provided by Ministry of Science &

Technology, DST, Govt. of India for INSPIRE program (Dy.No.100/IFD/10706/) under

Assured Opportunity for Research Carrier (AORC).





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