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Abstract  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 °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. [ABSTRACT FROM AUTHOR]

Abstract  Within a research program aimed to utilize natural zeolites for pedotechnical purposes, such as to rebuild degraded soils, to improve soil fertility and to remove soil pollutants, the adsorption process of humic acids (HAs) on untreated Neapolitan Yellow Tuff and on Ca2+-enriched samples was investigated in the temperature range 1–45°C. Experimental data showed a negligible temperature effect indicating that ΔH ≈ 0. Moreover, Scatchard-like plots suggested the occurrence of more than one adsorption sites for both samples. A good fit of the adsorption isotherms was obtained by two-site Langmuir equation. For both sites the HAs affinity was not modified by Ca2+-enrichment and ΔS° was >0. The adsorption of HAs on tuff is an entropy-driven process. [ABSTRACT FROM AUTHOR]

Abstract  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 organo-mineral 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°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. [ABSTRACT FROM AUTHOR]