On the zinc sorption by the Serbian natural clinoptilolite and the disinfecting ability and phosphate affinity of the exhausted sorbent.

The Serbian natural zeolite is moderately effective in removing the zinc(II) ions from aqueous solutions. At 298 K the sorption capacity varies from 13 to 26% for the initial Zn(II) solution concentration of 100 and 600 mg Zndm(-3), respectively. The sorption isotherm at 298-338 K is best represented by the Langmuir model and the sorption kinetics by the pseudo-second-order model. The sorption involves a combination of film diffusion, intra-particle diffusion, and a chemical cation-exchange between the Na(+) ions of clinoptilolite and Zn(2+) ions. The sorption was found to be endothermic and spontaneous in the 298-338 K range. The exhausted sorbent can remove phosphate ions and it exhibits an excellent antibacterial activity towards Acinetobacter junii. By dehydration at about 500 °C it transforms to a ZnO-containing product featuring nano-sized wurtzite ZnO particles widespread over the clinoptilolite surface.