Abstract
Adsorption properties and porous structure of acid treated natural heulandite-containing tuff from the Rkoni plot of the Tedzami deposit (Eastern Georgia), a mixture of heulandite and chabazite from the Chankanay deposit (Kazakhstan, Almaty region), and clinoptilolite-containing tuff from the Nor Kokhb deposit (Armenia, Noyemberian region), selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources, have been studied by water, benzene and nitrogen adsorption measurements. It was found that micropores of heulandite and clinoptilolite are in any case accessible to small water molecules; in Kazakhstani zeolite, they become accessible only after acid treatment, which also leads to a slight increase in surface hydrophobicity for all samples. Low-temperature nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the BET surface area, as well as changes in the mesoporous systems, leading to the prevalence of small pores with a diameter up to 4 nm in Georgian and Kazakhstani samples, and up to 3 nm in Armenian clinoptilolite, retaining larger pores in this sample, albeit reducing their volume.