Biosorption of Ni(II) from aqueous solutions by living and non-living ureolytic mixed culture.

The present study explores the ability and the comparison of living and non-living ureolytic mixed culture (UMC) to remove Ni(II) from aqueous solution. Time dependency experiments for the Ni(II) uptake showed that adsorption equilibrium was reached almost 110 and 60 min after addition Ni(II) of 100mg/L. The kinetic data were analyzed in term of pseudo-first-order and pseudo-second-order expressions. Ni(II) sorption of living UMC was appropriate with pseudo-first-order kinetic (k(1)=2.15 h(-1), R(2)=0.93) while non-living UMC sorbed Ni(II) with respect to second-order kinetics (k(2)=1.64 g/mgh, R(2)=0.98). Also, comparison between the biosorption capacity of untreated living and non-living biomass was conducted for removal of Ni(II). The biosorption process was investigated in equilibrium batch tests for Langmuir, Freundlich and Temkin isotherm models. The data pertaining to the sorption dependence upon Ni(II) ion concentration ranged from 5 to 320 mg/L could be fitted to a Freundlich isotherm model. The capacity constants K of Freundlich model for living and non-living UMC were 1.55 and 0.38 mg/g, respectively; the affinity constants 1/n were 0.47 and 0.75, respectively. Based on the results, the UMC appear to be a potential biosorbent for removal of Ni(II) from wastewater.