Nickel (II) Adsorption from Aqueous Solutions by Physico-Chemically Modified Sewage Sludge

This study assesses the potential of activated carbon prepared from sewage sludge for nickel ions adsorption from aqueous solutions. Activated carbon physicochemical properties were determined. Batch adsorption experiments were performed as a function of pH solution, adsorbent dose, initial metal ions concentration, contact time and temperature. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin isotherm models. The Freundlich model showed a better representation of equilibrium data (R2>0.99) and the Langmuir monolayer adsorption capacity of activated carbon was found to be 11.52 mg/g. The kinetics of nickel ions was discussed using different kinetic models and the adsorption experiments indicated that the pseudo-second-order model well fitted the kinetic data (R2=0.999). Thermodynamic parameters have also been evaluated. It was found that the adsorption process was feasible, spontaneous and endothermic. Desorption experiment and recovery of Ni(II) ions from activated carbon was found to be 100 % using hydrochloric acid. The results suggest that the activated carbon prepared from sewage sludge could be used beneficially for nickel adsorption from aqueous solutions for environmental cleaning purpose.