Biosorption isotherm study of Cd2Â +, Pb2Â + and Zn2Â + biosorption onto marine bacterium Pseudoalteromonas sp. SCSE709-6 in multiple systems

To overcome the low efficiency and prerequisites conditions of simultaneous metals removal and the unsuitability of single metal adsorption isotherm models in multiple metals, the multiple biosorption of Cd2 +, Pb2 + and Zn2 + onto a new marine Pseudoalteromonas sp. SCSE709-6 from aqueous solution was studied and compared with single metal system. Results showed that Pseudoalteromonas sp. SCSE709-6 was a competitive biosorbent for metals from aqueous solutions in single system (maximum adsorption capacity: 1.38 mmol g− 1 for Cd2 +, 1.05 mmol g− 1 for Pb2 + and 0.91 mmol g− 1 for Zn2 +, respectively). The affinity between metals and biosorbent calculated by the separation factor in binary metals systems followed the order: Pb2 + > Cd2 + > Zn2 +. In multiple metals systems, Cd2 + biosorption was the most sensitive, while Pb2 + biosorption was the least sensitive. In addition, Pb2 + biosorption had less pH dependence than the biosorption of Cd2 + and Zn2 +. Among six isotherm models applied in this study, the extended Freundlich isotherm model best described the binary metal biosorption behaviors. Isotherm analysis revealed that binary biosorption was a complex process which occurred both mono- and multi-layer biosorption. FT-IR result spectrum revealed that carboxyl, amide, acyl and hydroxyl played a significant role in metals biosorption. This study showed superior performance of metal removal by Pseudoalteromonas sp. SCSE709-6 in multiple metals systems.