Biosorption of Cr (III) from Aqueous Solutions Using Bacterium Biomass Streptomyces rimosus

In the present investigation, dead bacterium biomass Streptomyces rimosus was used as an inexpensive and efficient biosorbent for Cr (III) removal from aqueous solution. The bacterial biomass was treated with 0.1 M NaOH. Sorption level of 65 mg/g was observed at pH 4.8 while precipitation effect augmented this value at higher pH range. Chromium desorption increased with decreasing desorption agents pH (including HCl and H2 SO4 ) to a maximum value of 95% at approximately zero pH. Langmuir, Freundlich and Temkin models were applied to describe the biosorption isotherm of the metal ions by Streptomyces rimosus biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. Maximum metal uptake qmax was observed as 83.33 mg g”1 indicate good biosorbents than other biomass. Experimental data were also tested in terms of biosorption kinetics using fractional power, Elovich, pseudo-first order and pseudo-second order rate expressions. The results showed that the biosorption processes followed well pseudo- second-order kinetics and the intra-particle diffusion is not the rate-limiting step for the whole reaction.