Removal and recovery of chromium from wastewater using short chain polyaniline synthesized on jute fiber

In the present study, short chain polyaniline (PANI), a polymer was synthesized on the surface of jute fiber and was used as an adsorbent to remove hexavalent chromium (Cr(VI)). Experiments were conducted in batch mode with the variables such as amount of jute fiber on PANI, chain length of PANI, solution pH, initial concentration of Cr(VI), dose of PANI-jute and temperature. The PANI formed was found to be short chain polyaniline (oligoaniline). Optimum amount of jute fiber and chain terminating agent 1,4-phenylenediamine were observed as 5 g and 3.05 mmol, respectively, for 21.5 mmol of aniline. Maximum adsorption of total chromium (Cr(VI), Cr(Ill) and its other forms) was observed at reaction pH of 3 by electrostatic attraction of acid chromate ion with protonated PANI-jute. Adsorption equilibrium was achieved within 40-120 min for initial Cr(VI) of 50-500 mg/L. Maximum monolayer capacity of PANI-jute was observed as 62.9 mg/g at pH 3 and temperature 20 degrees C. Total chromium adsorption decreased with rise in temperature suggesting an exothermic adsorption of chromium. During desorption almost 83% efficiency was achieved within 10 min by 2 M NaOH. By ignition of chromium bounded PANI-jute, 94% Cr(VI) were able to recover as Cr(III) along with reduction in weight by 95%. PANI-jute can be used effectively to remove chromium from wastewater. (C) 2007 Elsevier B.V. All rights reserved.