Biosorption and Bioaccumulation of Cu2+ from Aqueous Solution Using Living M-amorphae Isolated from Mine Tailings

Mining generates large amounts of wastewater, which may contain elevated levels of potentially toxic metals. We evaluated the use of live cells of Mesorhizobium amorphae CCNWGS0123 as a new, relatively inexpensive and environment-friendly adsorbent material for removal of toxic metals from aqueous solutions, such as mine tailings leachate. Maximum copper uptake and removal efficiency was attained at a dosage of 0.5 g L-1, a pH of 5.0, an agitation speed of 150 rpm, and at a temperature of 28 A degrees C for an initial Cu2+ concentration of 100 mg L-1; equilibrium was achieved within 30 min. The adsorption isothermal data matched Langmuir and Freundlich isotherms well, with correlation coefficients of 0.931 and 0.932, respectively. FT-IR analysis indicated that many functional groups with a negative charge on the cell surface were involved in the interaction between live CCNWGS0123 and copper ions. Scanning electron microscope results confirmed that there was some copper sediment on the cell surface, causing deformation, aggregation, and cell surface damage. Cu2+ accumulation was related to cell growth, and copper uptake was not only due to cell-surface binding, but also to intracellular accumulation. Live cells of CCNWGS0123 are a new biosorbent that have the potential to be economical when small batches of biomass are used to remove Cu2+ from an aqueous solution.