In this present study, biosorption of Zn (II) from aqueous solutions by living bacteria Pseudomonas aeruginosa was investigated in batch experiments. The effects of pH, bacterial dosage, initial Zn (II) concentration, contact time, and temperature were studied. Removal process was influenced significantly by the variation of pH, biosorbent concentration, initial Zn (II) ion concentration, temperature, and contact time. Optimum biosorption conditions were found to be initial pH of 6, bacterial dosage of 0.5 g/l, initial Zn (II) ion concentration of 100 mg/l at room temperature, and contact time of 90 min. The maximum uptake capacity of P. aeruginosa for Zn (II) ions was found to be 46.1 mg/g at optimum conditions. The correlation coefficient for the second-order kinetic model was 0.997. The Langmuir and Freundlich isotherm models were also applied to the equilibrium of system and data were better fitted with the Freundlich isotherm. Finally, P. aeruginosa adsorption capacity was compared with other biosorbents. The abundant and economic biomass P. aeruginosa could be used for removal of Zn (II) from wastewater. Results showed that P. aeruginosa was an efficient biosorbent in the removal of Zn (II) ions from an aqueous solution.
