POLYMER SPONGES NANOCOMPOSITES FOR WATER REMEDIATION

Introduction/Purpose Novel multifunctional sponges based on poly-2-hydroxyethyl methacrylate (pHEMA) or polymethacrylic acid (pMAA) filled with Graphene Oxide (GO) were formulated with the aim to effectively remove organic pollutants from water. Our strategy involves also the deposition of ZnO on substrates to form a covalent linkage with the OH or COOH polymer pendant groups. Indeed, ZnO nanostructuration could provide the ability to degrade pollutants via photocatalytic process after the adsorption step. Methods The sponges were obtained by criopolymerization of monomers (HEMA, MAA) and the crosslinking agent in water solution (molar ratio of 6:1 and 1% w/w initiatior, of the total monomer), by adding GO as filler at -16 °C. The grafting of ZnO was performed by Atomic Layer Deposition at 80 °C. Morphological, thermal and mechanical investigations were carried out by using SEM, TEM, FTIR X-Ray analyses and TGA. Adsorption kinetics, porosity, equilibrium swelling degree and the photodegradation capability of cryogels were also evaluated [1]. Results The ZnO nanostructured polymeric sponges obtained as described above, showed high polymerization yields (80-85%), good mechanical and swelling properties as well as adsorption capability versus Methylene Blue (MB) and Atrazine [1]. To verify the efficacy of the regeneration process, adsorption of MB followed by its photocatalytic degradation was carried out. Three adsorptions were performed; between them, all samples were irradiated by UV lamps to regenerate the material via the photocatalytic action of ZnO. The adsorption results collected for each cycle (Fig. 1) showed as the percentage of adsorbed MB remains kostant for samples containing ZnO. Conclusions Hybrid sponges based on acrylate polymers and GO able to adsorb organic pollutant from water were formulated. MB degradation test showed as sponges containing ZnO have acquired photocatalytic properties. In particular, the recyclability tests revealed that pHEMA/ZnO materials can be easily regenerated and reused, explicating an effective remediation action versus organic pollutants. Selected references Ussia et al. ACS Appl. Mater. Interfaces, 10, 46, 40100-40110 (2018)