Physicochemical peculiarities of Georgian scolecite

Physico-chemical investigation of Georgian scolecite has been carried out to study the adsorption of water vapor on it and its modified forms (treated with HCl and NH4Cl); their thermal and ion exchange properties against mono (Li, Na, NH4, K, Cs, and Rb), divalent (Sr, Ba Ca, Mg) and transition (Cd, Cu, Mn, Zn, Co and Ni) metal cations. Treatment of the scolecite samples with different concentrations (0.05N, 0.1N, 0.25N, 1N, and 3N) of HCl changes its adsorption capacity, and scolecite exhibits comparatively high values when treated with 0.2 N acid. Scolecite's thermal analysis shows the stability of its microporous crystalline structure up to 450°C, which conditions the feasibility of its application as an adsorbent and nanomaterial. The structure of scolecite, the charge and size of the cations (both in the hydrated and dehydrated state), and cation concentration in the solution (0.1N, 0.3N, 0.5N, 1.0N, and 1.5N) determine the order of selectivity of scolecite against monovalent, divalent, and transition metal cations. Dynamic Exchange Capacity (DEC) values for the above cations on scolecite have been calculated.