The Applications of Natural Zeolites for Cadmium Removal from Sample Water: Models on Laboratory Scale

The removal of the cadmium ion from aqueous solution was studied in batch experiments using five natural zeolites were obtained from South of Thailnd, Clinoptiolite, Mordenite, Willhensonite, Offretite and Ferrierite, on the basis of experimental models on laboratory scale. Clinoptiolite was used for preliminary study of the adsorption parameters. An hour contact time and 40 g/L of the ratio of zeolite per water sample are optimum adsorption parameters with an average cadmium removal efficiency of 91.68 %. The optimum adsorption conditions were then used for other four natural zeolites. The results show that the effective removal sequence can be listed as Offretite  Clinoptiolite > Willhensonite > Mordenite > Ferrierite. Clinoptiolite, Offretite and Willhensonite are successfully used to reduce significantly cadmium from sample water with removal efficiency ranging from of 87-92%, respectively. Accordingly, the natural zeolites are recommendable adsorbents for highly cadmium removal of industrial wastewater with low cost of wastewater treatments and environmentally friendly chemical processes.