Chiang Mai Journal of Science

In this research, the ability of natural zeolite clinoptilolite to remove lead from aqueous solutions has been investigated in batch adsorption experiments. Adsorption tests of  Pb(II) were carried out using a solid to liquid ratio of 20 g/L and agitation speed of 700 rpm. The effects of particle size of the minerals (75-250 mm), solution concentration (100-1,200 ppm), initial pH (2-7), contact time (30-180 min) and temperature (30-75^oC) were examined. Experimental data obtained from batch equilibrium tests have been analyzed by Langmuir and Freundlich isotherm models. It was found that over 95% of  the initial Pb(II) amount for solution containing 800 ppm was removed in the 120 min and the optimum pH value of solution to be treated for adsorption was found to be 7. In adsorption studies, residual heavy metal ion concentration reached equilibrium in short duration of 30 min for initial Pb(II) concentration of  100 and 300 ppm. Maximum adsorption capacity, 58.73 mg Pb(II)/g zeolite at 75^oC, showed that this adsorbent was suitable for lead removal from aqueous media. Adsorption phenomena appeared to follow Langmuir and Freundlich isotherms. The results show that there is a good fit between the experimental data and empirical isotherms.