Influence of the Pyrolysis Temperature and TiO₂-Incorporation on the Properties of SiOC/SiC Composites for Efficient Wastewater Treatment Applications

This study focuses on the development of porous ceramer and SiOC composites which are suitable for microfiltration applications, using a mixture of polysiloxanes as the preceramic precursor. The properties of the membranes-such as their pore size, hydrophilicity, specific surface area, and mechanical resistance-were tailored in a one-step process, according to the choice of pyrolysis temperatures (600-1000 °C) and the incorporation of micro- (SiC) and nanofillers (TiO₂). Lower pyrolysis temperatures (<700 °C) allowed the incorporation of TiO₂ in its photocatalytically active anatase phase, enabling the study of its photocatalytic decomposition. The produced materials showed low photocatalytic activity; however, a high adsorption capacity for methylene blue was observed, which could be suitable for dye-removal applications. The membrane performance was evaluated in terms of its maximum flexural strength, water permeation, and separation of an oil-in-water emulsion. The mechanical resistance increased with an increase of the pyrolysis temperature, as the preceramic precursor underwent the ceramization process. Water fluxes varying from 2.5 to 370 L/m²·h (2 bar) were obtained according to the membrane pore sizes and surface characteristics. Oil-rejection ratios of 81-98% were obtained at an initial oil concentration of 1000 mg/L, indicating a potential application of the produced PDC membranes in the treatment of oily wastewater.