Chemical tailoring of graphene oxide and related composites for enhanced adsorption of water emerging contaminants

Water purification is a global issue and the pollution by emerging contaminants (ECs), such as per- and polyfluoroalkyl substances (PFAS), and pharmaceuticals, poses significant risks to human health and the environment. Traditional water treatment methods are often insufficient to remove ECs, calling for the urgent development of new technologies. In this context, graphene related materials (GRM) have gained increasing attention due to their exceptional properties. This thesis explores the potential of GRM as sorbents for the removal of ECs from drinking water, with a focus on the development of advanced composites that exploit both biopolymers and synthetic polymers as support matrices for GRM. This work examines the adsorption behaviour of water-dispersed GRM, in particular graphene oxide (GO), whose adsorption properties, i.e. selectivity and capacity, can be tailored by modifying its surface through covalent functionalization. Epoxide ring-opening reactions were used to graft various functional groups, including amino acids and β-cyclodextrin (βCD), onto the GO surface. In particular, functionalization with βCD was proven to be effective in the removal of perfluorobutanoic acid, a persistent PFAS. Although GRM have excellent adsorption properties, their need for dispersion and subsequent removal from water presents challenges. To overcome these limitations, the study focused on incorporating GRM into a polymer matrix. With this aim, alginate was used as a biopolymer to produce hydrogels, incorporating GRM to form a stable composite material that was tested for the removal of a selection of ECs. In addition to biopolymer-based composites, synthetic polymer systems were investigated, particularly polysulfone (PSU) hollow fiber membranes coextruded with GO. These membranes were developed for point-of-use water treatment technologies and tested for their efficiency in removing pharmaceuticals, heavy metals, and PFAS. A novel approach was also introduced to recycle PSU-GO industrial scraps into granular sorbents, which were tested in pilot plants under real tap water conditions.