Journal of Environmental Biology

Equilibrium and thermodynamic studies of Cd (II) biosorption by chemically modified orange peel

Arbind Kumar¹* and Vipin Kumar²

¹P.G. Department of Chemistry, D. S. College, Katihar-854 105, India????????????????????? ?????????????????????????????????????????????????????????

²Department of Chemistry, Kishanganj College of Engineering and Technology, Veriadangi, Kishanganj-855 107, India

*Corresponding Author E-mail: drarbindktr@gmail.com

Publication Data

Paper received:

28 November 2014

Revised received:

03 June 2015

Re-revised received:

03 July 2015

Accepted:

08 August 2015

Abstract

Agricultural wastes have great potential of removing heavy metal ions from aqueous solution. Removal of Cd (II) from aqueous solutions onto chemically modified orange peel was studied at different pH, contact time, initial metal concentrations, adsorbent doses and temperature. Batch experiments were carried out under optimized conditions to evaluate the adsorption capacity of orange peel chemically modified with NaOH.? The results showed that maximum adsorption capacity of modified orange peel, approximately 97.0 %, was observed 3 mg l^-1 of initial Cd (II) concentration pH 6 for 4 g l^-1 adsorbent? dosage, 200? min contact time and 298 K temperature. Adsorption efficiency of modified orange peel decreased with increase in temperature indicated exothermic nature of adsorption. A negative value of DG⁰ (-8.59 kJ mol^-1) confirmed the feasibility of adsorption process and spontaneous nature of adsorption. A negative value of DH⁰ (-28.08 kJ mol^-1) indicated exothermic nature while a negative DS⁰ (-66.86 J K^-1 mol^-1) value suggested decrease in degree of freedom of the adsorbed species. The results showed that biosorption process of Cd (II) ions by chemically modified orange peel is feasible, spontaneous and exothermic under studied conditions. Chemically by modified orange peel investigated in the present study showed good potential for the removal of cadmium from aqueous solutions. ??  

 Key words

Adsorption capacity, Cadmium, Chemically modified orange peel, Thermodynamic parameters

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