Influence of zeolite transformation in a homoionic form on the removal of some heavy metal ions from wastewater.

Influence of zeolite-clinoptilolite transformation in a homoionic (Na) form on zeolite ability to immobilize Pb2+, Cd2+, Cu2+, Zn2+ and Ni2+ from single ion and multi-component solutions has been studied. Zeolite in Na form exhibits significantly increased ability to remove Cd2+, Cu2+, and Zn2+ from their single ion and multi-component solutions when the water hardness due to Ca2+ presence is not high. Zeolite pretreatment with NaCl leads to increased rate of heavy metal ions' immobilization, as well as to increased distribution coefficients that are indicative for more complete exchange process. Heavy metal ions are more strongly bound to zeolite pretreated with NaCl, compared to natural zeolite. Heavy metal ions immobilization is due to ion exchange adsorption, both in the case of natural and converted in Na form zeolite. Zeolite pretreatment with NaCl practically does not change zeolite selectivity sequence for the ions investigated.