Humic substances (HS) are natural polymers produced by biological decomposition of plants and other organisms (Abate and Masini, 2003) and accounting for 50-80% of natural organic matter in water, soil and sediment. HS are generally subdivided into humin, humic acids (HA) and fulvic acids (FA) based on their solubility under acidic or alkaline conditions in aqueous solution. Among numerous methods developed for HA removal from water, adsorption is the most promising approach. Adsorption by low-cost materials, either natural or by-products of industrial activity, has become the focus of intensive investigation (Leone et al., 2012). Previous work (Capasso et al., 2007a; Capasso et al., 2007b) has shown that the Neapolitan yellow tuff (NYT), a volcanic rock rich in phillipsite/chabazite zeolites, binds HA through the action of surface extra-framework exchangeable cations, whereas HA molecules are too big to enter the system of channels and cages of zeolite crystals. The binding ability is markedly enhanced when the zeolitic material is enriched with divalent cations, especially Ca2+, that act as micro-bridges between negative charges on the zeolite surface framework and HA carboxylic groups. Moreover, it has been shown that HA adsorption by natural zeolites is a relatively long-lasting process with kinetic curves characteristic of a two-stage adsorption process (Ambrosone et al., 2013; Capasso et al., 2007b). Here we report a study on the HA adsorption onto a clinoptilolite-rich tuff. The influence of calcium ions and particle sizes were analyzed.

Water purification from humic acids by clinoptilolite-rich tuff

IOVINO, Pasquale;SALVESTRINI, Stefano;CAPASSO, Sante
2013

Abstract

Humic substances (HS) are natural polymers produced by biological decomposition of plants and other organisms (Abate and Masini, 2003) and accounting for 50-80% of natural organic matter in water, soil and sediment. HS are generally subdivided into humin, humic acids (HA) and fulvic acids (FA) based on their solubility under acidic or alkaline conditions in aqueous solution. Among numerous methods developed for HA removal from water, adsorption is the most promising approach. Adsorption by low-cost materials, either natural or by-products of industrial activity, has become the focus of intensive investigation (Leone et al., 2012). Previous work (Capasso et al., 2007a; Capasso et al., 2007b) has shown that the Neapolitan yellow tuff (NYT), a volcanic rock rich in phillipsite/chabazite zeolites, binds HA through the action of surface extra-framework exchangeable cations, whereas HA molecules are too big to enter the system of channels and cages of zeolite crystals. The binding ability is markedly enhanced when the zeolitic material is enriched with divalent cations, especially Ca2+, that act as micro-bridges between negative charges on the zeolite surface framework and HA carboxylic groups. Moreover, it has been shown that HA adsorption by natural zeolites is a relatively long-lasting process with kinetic curves characteristic of a two-stage adsorption process (Ambrosone et al., 2013; Capasso et al., 2007b). Here we report a study on the HA adsorption onto a clinoptilolite-rich tuff. The influence of calcium ions and particle sizes were analyzed.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11591/321427
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