equilibrium, mechanism, and mass transfer studies of nickel(ii) adsorption by sewage sludge-derived activated carbon

the present study was undertaken to evaluate the equilibrium, mechanism, and mass transfer of nickel(ii) ions adsorption on activated carbon derived from sewage sludge. batch adsorption experiments were performed as a function of initial ni(ii) ions concentration (10-50 mg/l) and contact time (10-120 min). the experimental data were analyzed by different models and freundlich model showed a better representation of equilibrium data (r^2 0.99) and the mean adsorption energy was found to be e= 3.98 kj/mol. mechanism study indicates that both external mass transfer (d2) and mass transfer diffusion coefficient (kl) are important in determining the adsorption rates (5.50 × 10^-5 cm/s and 7.30 × 10^-7 cm/s). we also found that nickel(ii) adsorption onto activated carbon would be attributed to a physico-chemical adsorption process. the results suggest that sewage sludge-derived activated carbon could be used beneficially as an effective and alternative adsorbent for the removal of nickel(ii) ions from aqueous solutions