Research on the Cr (VI) Absorption by Floc-Type Biosorbent AR

Abstract

Biosorptions of Cr (VI) by the floc-type biosorbent AR (with glycocalyx) and AR (without glycocalyx) were compared. The initial pH was important for biosorption, and the optimum effect on Cr (VI) biosorption was acquired within initial pH 0.5-1.0. With the pH increasing, the effect on Cr(VI) biosorption was reduced, and when the initial pH exceeded 3.0, the effect on Cr (VI) biosorption was in an equilibrium of low levels. Biosorbing Cr (VI) of different concentrations, the maximal absorbing capacity of AR (with glycocalyx) and AR (without glycocalyx) was 187.36 mg•g-1, 56.1 mg•g-1 respectively, and the glycocalyx adhering on the cell improved the absorption obviously. The absorbed Cr (VI) could be recovered by desorption, and the desorption rate of AR (with glycocalyx) and AR (without glycocalyx) reached 67.9%and 62.3% separately. The two biosorption processes conformed Langmuir and Freundlich isotherm adsorption equations, so we could presume that the progress of biosorptions was reversible adsorption and irreversible adsorption simultaneously, however the reversible adsorption was more important in the biosorption and the adsorption belonged to physical adsorption. Besides Agrobacterium sp. fermentation broth could be used as bioflocculant, Agrobacterium sp. could be applied as biosorbent, and the glycocalyx improved the absorption obviously, then both the bioflocculant and biosorbent were promising biological products