Emerging pollutants in water: innovative approaches of study and treatment

Water quality is one of the major challenges that human-ity has to face. Tackling the problem of pollution needs the use of all the resources and expertise available to fill the lack of knowledge and technology. Concern is grow-ing over the many emerging contaminants, including heavy metals ions and plastics, which are omnipresent and poorly managed. In this contest, the presence of micro- and nanoplastics in the marine environment is raising strong concerns. The lack of appropriate methodologies to collect the nanoplastics from water systems imposes the use of engi-neered model nanoparticles to explore their main charac-teristics and behaviour. In order to develop a nanoplastic model more reliable and realistic compared to the com-mon polystyrene nanospheres, in this thesis, laser abla-tion has been applied to induce the formation of plastic nanoparticles in water starting from a bulk polymer film. The process was performed on Polyethylene Tereph-thalate, a commercial polymer used to produce beverage bottles, widespread in the environment. PET nanoparti-cles with an average size <100 nm, were carefully charac-terized in terms of chemical/physical properties. Size, shape, surface chemistry and colloidal stability were ana-lyzed and compared with what expected from a real sam-ple. As the oral route has been defined as the main route for human exposure to nanoplastics, their biological in-teractions and the effects on single intestinal epithelial cells and on a model of intestinal barrier have been as-sessed. The aquatic environment exposes the nanoplastics to a great variety of substances and contaminants. The nanoplastics can therefore act as carriers for many toxic sub-stances with risks for aquatic organisms but also for hu-mans. The nanoplastic model was studied in presence of three model contaminants a pesticide, a drug and a heavy metal ion (glyphosate, levofloxacin and Hg2+ respec-tively). The binding capacity toward these contaminants, was demonstrated and characterized quantitatively and qualitatively. The synergic biological effect of the contam-inant-nanoplastic complexes was investigated in vitro on macrophages and intestinal epithelial cells. The conven-tional toxicological assays have been implemented with a preliminary metabolomic analysis. Concerning heavy metal ions pollution, considerable at-tention is being devoted to the development of low-cost and environmentally safe materials for their removal from polluted waters. Several strategies have been ap-plied to solve the problem of toxic metal ions contamina-tion in water, where the development of nanotechnol-ogy, and in particular of novel metal oxide nano-sorbents provides a promising and efficient alternative. The appli-cation of these technologies is however limited by the dif-ficult management of nanomaterials in the environment.Therefore, the use of a bionanocomposite made of titan-ate nanosheets embedded in a silk fibroin matrix was pro-posed as eco-friendly approach for water treatment ap-plications. The nanocomposite has been characterized and its ion exchange performances have been analysed under various conditions. The nanocomposites capacity to efficiently retain and adsorbed ions, with no release of titanate nanosheets has been proved. By modifying the nanocomposite formulation, it was also possible to en-hance the materials selectivity towards the lead ions.