Optimization of porous materials for environmental purposes

Cleaning up the environment of pollutants is one of the greatest challenges currently facing humanity. Adsorption processes can be helpful in limiting the amount of pollutants in the environment. For this reason, different types of porous adsorbents, from both commercial and synthetic origin, were used in this PhD thesis to remove pollutants from both gas and aqueous phases. Specific attention was given to the synthesis of silica-based monoliths and organically modified hybrid silicas (SOMS), and to the preparation of porous carbons derived from a Hyper Cross-linked Polymers (HCP). Moreover, four commercial porous carbons and commercial zeolite 13X are used as a comparison. The solids are characterised using a multidisciplinary approach to explore their chemical-physical properties. Concerning the adsorption of pollutants from the gas phase, the adsorption capacity of different materials to sequester two of the main greenhouse gases (CO2 and CH4) was studied. For this purpose, commercial porous carbons, commercial zeolite 13X and synthetic carbon, obtain from a HCP, were tested. Moreover, the ability of commercial porous carbons and commercial zeolite 13X to adsorb CH4 and N2 has been tested. In the field of biogas upgrading, the separation of N2 from CH4 is especially challenging, so the use of porous sorbents for the separation of these gas is also studied. Regarding the removal of pollutants in the liquid phase, this work focused on the removal of Rhodamine B and perfluoroalkyl substances (PFAS) from water. Rhodamine B was chosen since it is a model molecule capable of simulating a generic organic pollutant. Moreover, PFAS are a class of amphiphilic molecules, fully or partially fluorinated. Silica monoliths and SOMS were used to sequester RhB from water, and they were compared with a commercial zeolite. Regarding the removal of PFAS, SOMS and SOMS functionalized with molecules containing quaternary amine groups (QASOMS), to make them more selective, have been tested.