Graphene based materials for water purification: characterization and application

This PhD thesis addresses the critical issue of water purification, an evolving field with increasing importance year by year, as highlighted by the recent revision of EU Drinking water directive (EU2020/2184). Current water treatment methods are insufficient for efficiently removing Emerging contaminants (ECs) and new materials and technologies are required. Among these strategies, graphene-based materials, particularly Graphene Oxide (GO), have emerged as promising candidates for water purification. Key properties of GO are remarkable surface area, multi-site interaction with organic molecules and tailorable surface chemistry. The research objective was to assess GO effectiveness in different configurations (i.e., nanosheets, composites) as a sorbent of various ECs, such as pharmaceutical and personal care products, heavy metals, and Per- and Poly-Fluorinated Substances. To investigate the adsorption mechanism of GO, a standardized protocol based on adsorption, kinetic and efficiency tests was employed together with molecular dynamics simulations. To fully exploit the adsorption capacity of GO as nanosheets, a two-step set-up was proposed (GO+MF), combining batch adsorption and microfiltration. Taking a step further in applicability of GO in water purification, Polysulfone-GO hollow fiber membranes (PSU-GO HFs) were developed by coextrusion. The composite exploit simultaneous adsorption and ultrafiltration capabilities in a single module, suitable for point of use application. In addition, the adsorption capacity of GO was selectively enhanced through covalent surface modification. GO modified with Amino acids (GO-AA), including L-glutamic acid, L-methionine, and Lysine. GO-AA exhibited significantly improved adsorption capacities towards select contaminants, and the role of grafting was deeply investigated. These findings highlight GO potential in water purification, providing valuable perspectives for future applications.