The influence of pretreatment on the capacity and selectivity of natural zeolite for Zn2+ and Mn2+ ions has been studied. Natural tuff (sample 1), consisting mainly of zeolite clinoptilolite, was converted into the Na+ form by conditioning with 2 M NaCl at 22 °C (sample 2) and 70 °C (sample 3), respectively. Simultaneously, 0.26,
0.31, 0.38 mmol Zn2+ and 0.20, 0.23, 0.30 mmol Mn2+ were taken up by 1.00 g of zeolite samples 1, 2 and 3, respectively. The results show that zeolites converted to the Na+ form at 70 °C possess the highest capacity for metal ions. For all the zeolite samples tested, zinc was more selectively removed than manganese. The amount and composition of exchangeable cations as well as their impact on ion-exchange performances of zeolite in the process of Zn2+ and Mn2+ removal were determined
