Removal of chromium(VI) from water and wastewater using surfactant modified coconut coir pith as a biosorbent

Published Date
May 2008, Vol.99(7):2218–2225, doi:10.1016/j.biortech.2007.05.023

Author 

C. Namasivayam ^,

M.V. Sureshkumar

• Environmental Chemistry Division, Department of Environmental Sciences, Bharathiar University, Coimbatore 641046, India

Received 4 January 2007. Revised 11 May 2007. Accepted 13 May 2007. Available online 29 June 2007.

Abstract

Coconut coir pith, an agricultural solid waste was used as biosorbent for the removal of chromium(VI) after modification with a cationic surfactant, hexadecyltrimethylammonium bromide. Optimum pH for Cr(VI) adsorption was found to be 2.0. Reduction of Cr(VI) to Cr(III) occurred to a slight extent during the removal. Langmuir, Freundlich and Dubinin Radushkevich (D–R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms. The adsorption capacity of the biosorbent was found to be 76.3 mg g⁻¹, which is higher or comparable to the adsorption capacity of various adsorbents reported in literature. Kinetic studies showed that the adsorption obeyed second order and Elovich model. Thermodynamic parameters such as ΔG⁰, ΔH⁰ and ΔS⁰ were evaluated, indicating that the overall adsorption process was endothermic and spontaneous. Effects of foreign anions were also examined. The adsorbent was also tested for the removal of Cr(VI) from electroplating effluent.

Keywords

Coir pith

Chromium(VI)

Biosorption

Kinetics

Isotherms

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