Anions effects on biosorption of Mn(II) by extracellular polymeric substance (EPS) from Rhizobium etli.

Microbial extracellular polymeric substances (EPS) are potential biosorbents for metal remediation and recovery. The Langmuir and Freundlich kinetics of Mn(II) binding by the EPS from a novel Mn(II) oxidising strain of Rhizobium etli were determined. Maximum manganese specific adsorptions (q(max)) decreased in the sequence: sulphate (62 mg Mn per g EPS) > nitrate (53 mg g(-1)) > chloride (21 mg g(-1)). Consideration of the anion during kinetic studies is usually neglected but is important in providing more practical and comparable data between different biosorbent systems.