CO2+ ION-EXCHANGE WITH NAY

Co2+ ion exchange from aqueous cobalt chloride-sodium chloride solutions with NaY zeolite has been investigated. The effect of contact time on the sorption of Co2+ by dehydrated Y zeolite at 150-degrees-C is unusual. A fast sorption uptake is observed in which 1.73 mequiv/g of zeolite of Na+ ions is replaced by cobalt ions, followed by a desorption process where the uptake decreases to 1.56 mequiv/g of zeolite. This behavior is explained by the location and coordination of cobalt in Y zeolite sites. It is suggested that the maximum uptake corresponds to cobalt ions being simultaneously in two sites; tetrahedrally coordinated in the sodalite units and octahedrally coordinated in the large cavities. It is also suggested that the desorption process is a consequence of a reaction between Cl- ions and the tetrahedral species.