Geopolymer-based materials for the removal of phosphates and ammonium from wastewaters

Geopolymers are widely used as environmentally friendly adsorbent materials, especially because of their peculiar and tunable porosity. Furthermore, the presence of negative charge on the SiO4 and AlO4 tetrahedron network makes them suitable as ion exchangers, e.g. for the NH4+ ion. In this study, geopolymer-based materials were synthesised to obtain adsorbents for the removal of pollutants from wastewater. Hydrotalcite was used as filler in the geopolymer matrix because its addition allows the simultaneous removal of ammonium and phosphate. In particular, after testing several commercial hydrotalcites, in term of phosphate adsorption capacity, the best performant one resulted to be Sorbacid 911. With the aim of improving the adsorption capacities, foams were produced through the technique of the direct foaming and then granulated. Composites and pure materials were tested in batch and continuous trials using real wastewaters. Research activities are carried in the framework of the MUR PRIN 2022 Project GEA - GEopolymer based Adsorbents for effective adsorption and selective separation of CO2 and eutrophication pollutants, - Prot. 20229THRM2, funded by the European Union – Next Generation EU.