Equilibrium, kinetic and thermodynamic studies on biosorption of lead(II) and cadmium(II) from aqueous solution by polypores biomass

Polypores (woody pore fungi) biomass has been used as an biosorbent for the removal of Pb(II) and Cd(II) from aqueous solution under batch equilibrium experimental conditions. The resulting biosorbent is characterized by SEM and FTIR techniques. The effect of experimental parameters, such as solution pH, biomass dosage, contact time, initial metal ion concentration and temperature of Pb(II) and Cd(II) have been evaluated on the metal uptake performance. The pH for optimum biosorption is found to be 5.0 for Cd(II) (92.5% removal) and Pb(II) (96.4% removal). The adsorption kinetic data are best described by pseudo-second-order kinetic model with good correlation coefficient and low error function values. The experimental results indicate that the Langmuir isotherm describes the biosorption of Cd(II) and Pb(II) ions onto the biomass better than the Freundlich, Dubinin-Radushkevich (D-R) and Temkin models at all the temperatures studied. The calculated thermodynamic parameters (∆G, ∆H and ∆S) show that the biosorption of both metal ions is feasible, spontaneous and exothermic in nature at 303–313 K. Based on the results obtained such as good uptake capacity and its low cost, polypores biomass appears to be a promising biosorbent material for the removal of Cd(II) and Pb(II) ions from aqueous media.