Removal of lead from aqueous solution using groundwater sludge

Lead (Pb) is present in effluents from a number of industries e.g. storage batteries, gasoline additives and other chemicals, ammunition, solder, etc. This research is a study on the effectiveness of groundwater sludge as a low cost adsorbent for Pb (II) adsorption from aqueous solution. The groundwater sludge (GWS) was collected from Air Kelantan Sdn Bhd., Kelantan, Malaysia treatment plant. It was dried at 105 °C for 24 h and grinded before laboratory experiments were conducted. The removal of Pb (II) was studied by conducting batch tests at room temperature (28 ± 1 ºC) using an orbital shaker. The optimum initial pH for maximum uptake of Pb (II) from aqueous solution was found to be 5.5. The optimum contact time was 60 minutes for initial Pb(II) concentrations up to 150 mg/L and 150 minutes for initial concentration of about 200 mg/L. Langmuir isotherm (R2 = 0.9497) was found to describe the process better than Freundlich isotherm (R2 = 0.5188). Both pseudo-first and pseudo-second order kinetic models yielded high R2 values (> 0.93).