Speaker
Descrizione
Within the framework of the MSCA-DN "UP2MEM" project (funded by EU Horizon Europe MSCA-DN No 101227653), this study presents a sustainable "waste-to-resource" strategy for the synthesis of CaTiO3-TiO2-nanocarbon (CaTi-nC) based assemblies to be used as photo catalytic and antibacterial coatings in wastewater ceramic membranes. CaTiO3 perovskite oxide has the role of photocatalyst for degradation of organic contaminants in wastewater, TiO2 acts as an antibacterial component, whereas nanocarbons, beside their affinity toward hydrophobic membranes, act as microstructural template and enhance visible-light absorption through synergy with the CaTiO3 perovskite oxide. End-of-life sunscreen waste, such as industrial expired batches and retail returns, is directly used as source of both Ti (as TiO2 screen component) and chelating agents (as organic emulsifiers). The first step involves the characterization of different waste sunscreens using thermal decomposition, thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD), to identify/quantify the inorganic content and determine the thermal decomposition profile of the organic content. Following the solution combustion synthesis methodology, the waste with the highest content of TiO2 is then added to calcium nitrate, with an increasing amount of citric acid, as a co-reducing/chelating agent and other synthesis additives. This synthesis approach exploits the self-sustaining exothermic reaction between the metal nitrates and the organic components to produce mixed oxide phases at reduced temperature/time/energy. A reference powder is also prepared to reproduce a perovskite-oxide-nanocarbon assembly by using the same preparation methodology, with a commercial TiO2 powder employed as Ti precursor, adding the same amount of nanocarbons and using citric acid as unique reducing/chelating agent. X-ray powder diffraction (XRD) combined with Rietveld analysis is used to determine the overall phase composition and to confirm the successful conversion of waste derived TiO2 to the orthorhombic CaTiO3 perovskite oxide structure. Scanning and Transmission Electron Microscopy (SEM/TEM) and N2 adsorption-desorption experiments are used to identify the microstructural and morphological features of the powders and to compare them with the reference powder. Temperature programmed reduction experiments are performed to analyze the reduction properties of reducible species (Ti) in the powders. Preliminary dip-coating experiments from the combustion sol are described for the functionalization of small pieces of commercial ceramic ZrO2 and SiC membranes. These experiments are finalized to the optimization of the sol’s chemical composition to improve coating adhesion and structural integrity without blocking the membrane pores and compromise the membrane permeability.
| Giovane Ricercatore (under 40) | Yes |
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