Comparative ion-exchange characterization of zeolitic and clayey materials for pedotechnical applications - Part 2: interaction with nutrient cations

With the purpose to evaluate the possible use of a phillipsite-rich tuff, in place of the naturally occurring clay minerals, as inorganic ion-exchanger component of organo-mineral aggregates of pedotechnical interest, the ion-exchange behavior of Neapolitan yellow tuff and a reference montmorillonite-rich material towards some nutrient cations was investigated. Accordingly, exchange kinetics and isotherms of Na+, K+, and NH4+ for Ca2+, at 25 degrees C and 0.1 total normality, were determined, and the related kinetic and thermodynamic quantities computed. The obtained results point out that the zeolitic material, apart from a higher cation exchange capability, exhibits selectivity performances towards nutrient cations comparable or even better than those of the montmorillonitic material, confirming, on the basis of the previous data concerning noxious cations, that phillipsite-rich tuffs can be considered potential substitutes of clay materials to recover and/or rebuild polluted and degraded soils.