EFFECTS OF CONDITIONING AND TREATMENT OF CHABAZITE AND CLINOPTILOLITE PRIOR TO LEAD AND CADMIUM REMOVAL
This paper characterizes two natural zeolites, chabazite and clinoptilolite, and investigates the effects of treatment and conditioning on the removal of Pb and Cd from effluent wastewaters. The results demonstrated that the as-received zeolites contained a complement of exchangeable K, Ca, and Na ions but exposing them to concentrated NaCl solutions converts them to a homoionic state in the Na form, which improves significantly their exchange capacity. Particle size was found to have no effect on the exchange, suggesting that the mechanism is not surface controlled. Pb and Cd removal results using as-received, conditioned, and treated zeolites showed that conditioning and treatment improved both the exchange capacity and the removal efficiency when operating at metal concentrations greater than 250 mg/L.