Biosorption of Cu2+ and Ni2+ ions from aqueous solutions using waste dried activated sludge biomass

Adsorption of Cu(II) and Ni(II) ions onto the waste powdered activated sludge biomass (PWB), which was obtained from the biological wastewater treatment plant, was investigated in this experimental study. The effects of contact time, pH, temperature, initial sorbate and sorbent concentrations on the adsorption were determined. The BET surface area, pore volume, and pore diameter of PWB were found to be about 0.51 m(2)/g, 0.0053 cm(3)/g, and 41.4 nm, respectively. Considering the R-2 value, q(exp) and q(cal), the Langmuir and Freundlich models were well described for Cu(II) and Ni(II) adsorption, respectively. The adsorption mechanism of Cu(II) and Ni(II) onto the PWB could be better simulated by the pseudo-second-order kinetic mechanism than the pseudo-first-order, intra particle diffusion and Elovich models. Thermodynamic aspects of the adsorption of heavy metals were also investigated. Considering the applied desorbing agents for reuse of PWB for Ni(II) recovery, desorption cycle is not feasible due to the deterioration of the PWB structure.