Application of polyaniline and its composites for adsorption/recovery of chromium(VI) from aqueous solutions

This paper deals with adsorption of Cr(VI) from aqueous solutions using sawdust coated by polyaniline (SD/PAn) and polyaniline composites with nylon 66 and polyurethane. Nylon and polyurethane are available common polymers that can be easily dissolved in the solvents of PAn (formic acid and NMP). So, the PAn composites with these polymers can be readily prepared via solvent cast method. Polyaniline (PAn) was synthesized chemically and coated on the surface of sawdust (SD) from formic acid via cast method. It was found that polyaniline in the acid doped form (e.g. HCl), can be used for Cr(VI) ion removal in acidic aqueous solutions (pH :5 2). Adsorption occurs only under acidic conditions and it decreases with increasing the pH of solution significantly. The proposed mechanism for adsorption of Cr(VI) with our currently developed adsorbent seems to be mostly occurring via an anion exchange process. Adsorption of Cr(VI) from water using SD/PAn column is both a simple and efficient method compared to the other adsorbents reported by previous investigators.