Effective Removal of Chromium (VI) Ions from Tannery Effluent using Chitosan-Alumina Composite
Mrinal Kanti Kabiraz *
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh and Department of Applied Chemistry and Chemical Engineering, University of Dhaka, Dhaka-1000, Bangladesh
Ismet Ara Jahan
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh
Shah Md. Masum
Department of Applied Chemistry and Chemical Engineering, University of Dhaka, Dhaka-1000, Bangladesh
Md. Monarul Islam
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh
S. M. Mahmudul Hassan
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh
Badhan Saha
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh
Husna Purvin Nur
BCSIR Laboratories Dhaka, Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhanmondi, Dhaka-1205, Bangladesh
*Author to whom correspondence should be addressed.
Abstract
A chitosan-alumina composite was prepared by coating chitosan, a glucosamine biopolymer, on activated alumina to remove chromium (VI) ion from tannery effluent. Chitosan was prepared from by demineralization and deproteinization of indigenous shrimp shell collected from Khulna, Bangladesh and was characterized using FTIR, X-Ray Diffraction (XRD) & Scanning Electron Microscopy (SEM). The composite was prepared by simple solution-evaporation method and was characterized using XRD & SEM. Batch isothermal equilibrium experiments were conducted to evaluate the biosorbent for the removal of hexavalent chromium (VI) from stock solution as well as effluent obtained from tanneries in local area. The optimum pH, dose, and contact time on adsorption was also investigated. Removal of Cr(VI) was found to be dependent on pH and maximum adsorption was observed at pH 2.0. The optimum dose and contact time for Cr(VI) treatment was 25 g/L and 240 minutes respectively. Experimental equilibrium data were fitted to Freundlich adsorption. The concentration of Cr(VI) was determined by Atomic Absorption Spectroscopy (AAS). The Cr(VI) removal efficiency of the prepared chitosan-alumina composite was 90.17% and for tannery effluent the Cr(VI) removal efficiency was found as 87.88% under the optimum conditions. Efficiency of Cr(VI) ions removal in terms of adsorption capacity was found to be in the order of chitosan-alumina composite>chitosan>alumina.
Keywords: Chitosan-alumina composite, X-Ray Diffraction (XRD), chromium (VI), Scanning Electron Microscopy (SEM), sorption, tannery effluent treatment, chitosan