Ion-exchange equilibria of synthetic 13X zeolite with Ni2+, Co2+, Zn2+ and Cd2+ ions

Abstract

Samples of Linde 13X zeolite with 97.5 % of their sodium ions replaced by Cd²⁺, 76.5 % by Zn²⁺, 75.4 % by Co²⁺ and 71.7 % by Ni²⁺ were studied by chemical analysis, differential thermal analysis, thermogravimetric analysis and X-ray analysis to determine their unit cell composition and thermal stability. Ion-exchange isotherms at 5, 25 and 45°C for the M²⁺–Na⁺ exchange are reported and the thermodynamic quantities ΔG°, ΔH° and ΔS° calculated. The results are discussed with respect to hydration of cations, the possible sites they occupy in the zeolite and chemical reactions in the liquid phase.