Study of adsorbent derived from sewage sludge for the removal of Cd2+, Ni2+ in aqueous solutions

The adsorbent derived from sewage sludge through chemical pyrolysis has been used for the adsorption of Cd2+ and Ni2+ from aqueous solution. Parameters such as the agitation time, metal ion concentration, adsorbent dosage and pH were studied. The adsorption data fit well with the Langmuir and Freundlich isotherm models. The capacity of adsorption calculated from the Langmuir isotherm was 16, 9 mg/g for Cd2+ and Ni2+, respectively at the initial pH of 5.8 at 25 degreesC. And the agitation time of 60 min was necessary for the adsorption to reach equilibrium, the optimum pH value in the range of 5.5-6.0. Desorption studies were performed with dilute hydrochloric acid. Quantitative recovery of the metal ion is possible. The mechanism of adsorption seems to be ion exchange. As the sewage sludge is discarded as waste from wastewater treatment processing, the adsorbent derived from sewage sludge is expected to be an economical product for metal ion remediation from water and wastewater. (C) 2003 Elsevier B.V. All rights reserved.