Biosorption of chromium(VI) using immobilized Bacillius subtilis and Pseudomonas aeruginosa

Abstract

Heavy metals like chromium do contaminate the environment that comprises of soil, water and air. It affects the growth of flora and fauna which in turn affect human health negatively. Chromium could also bio-accumulate in plants and animals and this becomes dangerous for survival of human if adequate steps are not taken for treatment of industrial and agricultural wastes. Therefore, the batch removal of Cr (VI) from environment water bodies becomes necessary. Its removal from aqueous solution using immobilized Bacillus subtilis (IBBS), Pseudomonas aeruginosa (IPBS), mixed biomass (IMBS) and Alginate alone (IABS) was carried out. The conditions of influence of initial Cr (VI) concentrations, solution pH, contact time, biomass dosage and temperature were studied. The sorption kinetic models of Cr (VI) onto the biosorbents were examined with pseudo first-order, pseudo second-order, and Elovich kinetics respectively. It was found that the experimental conditions affected the extent of removal of Cr (VI) from aqueous solution. The higher the initial concentration, the larger the amount of Cr (VI) removed while the higher the temperature the lesser the amount removed. The optimum contact time and adsorbent dose for effective removal of Cr (VI) from aqueous solution were found to be 60 mins and 0.01 g respectively. Pseudo second-order kinetic model best correlates the experimental data. Among isotherm models studied, Freundlich adsorption isotherm model gave the best fit.

Key Words: Chromium (VI), Adsorption Kinetics, Adsorption Isotherms, Spectrophotometric Determination, Immobilized Biosorbents