Removal of lead in fixed bed using natural zeolite clinoptilolite

Abstract

This work investigated the removal of lead ion using natural zeolite clinoptilolite. The study was done using a cylindrical fixed bed column built in acrylic with a height of 13.3 cm and an internal diameter of 1.4 cm. Experimental assays were carried out varying the liquid flow rate from 10 to 50 mL/min to determine the optimum operational conditions which minimizes diffusion resistance. Length of mass transfer zone and column capacity analyzed indicated that the best flow rate was 20 mL/min among the conditions studied. In order to determinate the pH range at which minimized lead precipitation occurs a pH variation study was developed. The minimum amount of precipitation occurred in pH levels from 3.0 to 5.0. Operating conditions for the maximal lead ion removal were determined using the factorial design and response surface techniques. The variables under investigation were lead initial concentration and feeding flow rate. In the range of values studied, only the variable concentration was found significant. The model obtained by surface methodology was statistically significant and predictive with 98.9% of confidence. The zeolite maximal capacity of lead ion removal was predicted by the model at 200.54 mg of Pb/g de zeolite. Keywords: adsorption, lead, zeolite, fixed bed.