Evaluation the feasibility of using clinoptilolite as a gravel pack in water wells for removal of lead from contaminated groundwater

Abstract

The ability of clinoptilolite zeolite as a filter in water wells to remove lead from polluted groundwater was tested in batch and fixed-bed column experiments. XRF, XRD, SEM, and BET were used to characterize the zeolite. Because of the pH variation in groundwater, batch experiments were performed at pH = 6, 7, and 8, with the highest removal efficiency (84.2%) at pH = 6 and 298 K within 90 min. The Freundlich model accurately predicted metal ion adsorption behavior and indicated a multilayer adsorption of Pb(II) molecules on the inhomogeneous surface of clinoptilolite. The best-fitting kinetic model for clinoptilolite is the pseudo-second order equation, highlighting that the rate of adsorption is dependent on absorbent capacity. Next, the effect of flow rate, bed depth, and grain size of clinoptilolite on lead removal was investigated in column experiments at an initial concentration of 450 mg pb/L. The highest removal efficiency was achieved in column experiments with a flow rate of 1 mL/min, a bed height of 10 cm, and a grain size of 0.6 to 0.8 mm. Breakthrough curves were predicted by the Thomas and Yoon-Nelson models, with excellent agreement with the corresponding experimental data. This research will be used to develop a new in situ remedial approach for removing lead from polluted groundwater.