Application of zeolite prepared from Egyptian kaolin for removal of heavy metals: I. Optimum conditions

The optimum conditions for removal of heavy metals using zeolites A and X prepared from local kaolin zeolite were studied in order to apply it in industrial wastewater treatment. Metal removal was investigated using synthetic solutions at initial concentrations of 20 mg/L of individual metals (Cd, Cu, Pb, Zn and Ni) and mixture of the pre-mentioned metals with concentration of 20 mg/L for each at constant temperature and pH (25 +/- 0.1 degrees C and 7.5 +/- 0.2) respectively. The removal efficiency was determined at different contact time and different zeolite doses. The optimum contact time for removal of Cd, Cu, Pb and Zn was 30 min for both zeolite types. On the other hand, optimum contact time for Ni removal was 60 min for both zeolite types. 0.8 g was the optimum dose for removal of all metals in case of zeolite X. The same trend was obtained in case of zeolite A except for Pb removal which has an optimum dose of 0.4 g. Locally prepared zeolites A and X were highly efficient in heavy metal removal at optimum conditions and nearly equal due to presence of 8 faces including nanometer pours in the prepared zeolite enabling it for being effective in some molecular sieve separation of small molecules. The adsorption and desorption behaviours with respect to the studied metals are investigated in the running work. (C) 2010 Elsevier B.V. All rights reserved.