Biosorption of Cr(VI) by Metal Resistant Bacteria from Industrial Effluent

Chromium biosorption was found to be influenced by the pH of the solution, initial metal concentration, amount of the dried powdered cells and contact time. Batch biosorption of chromium(VI) from an aqueous solution was studied using dry biomass of inactivated bacteria isolated from the industrial effluent. At the initial metal ion concentration of 50 mg L-1, the Cr(VI) adsorbed was 7.14 mg g(-1) of adsorbent. At 300 mg L-1 initial Cr(VI) concentration, removal of 47.02 mg g(-1) of Cr(VI) was recorded. The Cr(VI) adsorbed increased with increasing initial metal ion concentration up to 300 mg L-1. Optimum biosorption was recorded at pH 3. At all the concentrations, the adsorption equilibrium was obtained within 6 h. The adsorption equilibrium constants were obtained from both Freundlich and Langmuir adsorption isotherms. The organism could remove 60 mg of Cr(VI) per gram of adsorbent from an effluent (300 mg L-1) at pH 3. Several desorping agents like EDTA, oxalic acid, citric acid etc. were used for desorption process of which citric acid was found to be better desorping agent. Immobilization with alginate preparation was found to maintain the biosorption potential.