Continuous elimination of Pb2+, Cu2+, Zn2+, H+ and NH4 + from acidic waters by ionic exchange on natural zeolites.

A study of breakthrough curves for cations usually found in acid mine drainage (Pb(2+), Cu(2+), Zn(2+) and H(+)) and municipal wastewater (NH(4)(+)) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by X-ray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Pará (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb(2+) and NH(4)(+) as received, and also a very high exchange capacity for Cu(2+) and Zn(2+) when conditioned with 2M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs: CLI-1 > HEU-2 > HEU-1 > STI-2. Since it is true for most of the cations studied.