Comparative ion-exchange characterization of zeolitic and clayey materials for pedotechnical applications. Part 1. Interaction with noxious cations

With the purpose to set up a convenient strategy to rehabilitate degraded soils by recovering their functionality, the possibility of using zeolitized tuff as inorganic ion-exchanger components of organomineral aggregates, in place of the naturally occurring clay materials was estimated. Accordingly, after the evaluation of a suitable method for measuring the cation exchange capacity of both materials (a phillipsite-rich tuff from the surroundings of Naples, Italy, and a bentonite, from Wyoming, USA), exchange kinetics and isotherms Of Cu2+, Pb2+ and Zn2+ for Ca2+ at 25 degrees C and 0.1 total normality, were determined and the related kinetic and thermodynamic quantities computed. Comparative results demonstrate that phillipsite-rich tuffs exhibit higher cation exchange capability and selectivity performances towards noxious cations than the montmorillonite clay does, and therefore that they can be considered good substitutes of clay materials to recover and/or rebuild polluted and degraded soils.