The removal of copper and nickel from aqueous solution using Y zeolite ion exchangers

Abstract

Nickel and copper removal from aqueous solution by batch ion exchange with solid lithium-, sodium-, potassium-, rubidium- and caesium-based Y zeolites have been studied under competitive and non-competitive conditions. The extent of transition metal (TM) removal is dependent strongly on the nature of the out-going alkali metal (AM) cation with the overall preference of the zeolite for exchange with both metals increasing in the order CsY<RbY<NaY<LiY. Equilibrium exchange isotherms are presented, and the effect of increasing the treatment temperature from 298 to 373 K on exchange selectivity is illustrated. An increase in solution phase TM concentration lowers the affinity of the zeolite for the in-going TM ion but copper was preferred to the indigenous AM ion at initial copper to zeolite ratios <0.1 mol dm −3 g −1 regardless of the parent zeolite. Copper removal was much greater than that of nickel for all the zeolite exchangers under identical experimental conditions with a maximum recorded exchange efficiency of 64% and separation factor of 33. In addition, treatment of copper/nickel solutions resulted in a greater depletion (by a factor of 1.3) of the copper component. Regeneration of the used zeolite by back exchange is also considered.