Synthesis of zeolite from volcanic ash: Characterization and application for cesium removal

Mt. Etna, the largest volcano in Europe, is periodically interested by intensive eruption activity sometimes causing environmental problems for the neighbouring urban areas such as Catania. The volcanic ash deposited on the roads is classified as waste (code 20 03 03 - municipal waste from European Waste Catalogue - EWC). In this work, with the aim to transform waste materials into useful product, two samples of ashes resulting from different explosive activities were treated by hydrothermal aging with distilled water and seawater. The results showed that the hydrothermal process determined mineralogical and magnetic changes in volcanic ashes. The data in fact indicated that X-type zeolite and sodalite were formed at 45, 60 and 70 °C of aging temperature. Moreover, magnetic characterization suggests an evolution of ferromagnetic materials to antiferromagnetic ones during zeolite formation. The presence of these new magnetic phases was responsible for the variety of magnetic behaviour. The applicability of obtained zeolite as novel adsorbent material in the field of water treatment was also evaluated. Batch adsorption experiments were carried to assert the adsorption capacity of novel synthetized zeolite in removing cesium ions from aqueous solutions thus confirming a possible End-of-Waste alternative.