Modified coconut shell fibers: A green and economical sorbent for the removal of anions from aqueous solutions

The powder of green coconut shell (Coco nuscifera L) was chemically modified and used to remove inorganic anions from aqueous solution through batch process. The solid was modified with ammonium quaternary salt (2-hidroxypropyltrimethyl ammonium chloride) and characterized by a full factorial design. The FTIR, elemental analysis, SEM and X-ray measurements were performed. FTIR analysis indicated that the coconut bagasse interacted with NH2 groups of the surfactant. Initial anion concentration, pH and adsorbent dosage were investigated in this study, as well as the kinetics of adsorption and isotherms for the modified coconut bagasse. Kinetics of adsorption was examined by means of three kinetic models, i.e., pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Pseudo-second-order kinetic model showed good agreement with the experimental data. Data on equilibrium were evaluated by using Langmuir, Freundlich, SIPS, Redlich-Peterson, Temkin models. It was observed that the experimental data fits well to Langmuir, SIPS, and Redlich-Peterson equations. The results indicated that the modified coconut powder exhibited potential application for removal of nitrate, sulfate and phosphate from aqueous solutions. (c) 2012 Elsevier B.V. All rights reserved.