Abatement of parabens by porous, hydrophilic and photocatalytic P25/PDMS membranes

Polydimethylsiloxane (PDMS) is a promising support for photocatalysts for wastewater treatment. However, despite the favorable performance of PDMS-supported photocatalysts, few studies evaluate its reusability, and those that do, perceive a low reusability for smooth and non-porous materials. Thus, the present study proposes synthesizing porous PDMS-supported photocatalysts using the soft template method (or emulsion template method) followed by a grafting process. This is an innovative and low-time-consuming method to promote porosity. During the soft template method, non-solvents that meet the requirements of green chemistry were used, such as ethanol, acetone, and water. The amount of non-solvent and photocatalyst added was optimized. It was found that producing PDMS-supported photocatalysts with ethanol makes it possible to obtain flexible, porous, and stickier materials, with a higher surface area. Porous PDMS-supported photocatalysts prepared with a mass ratio between the content of ethanol and PDMS equal to one and immersed in a P25 dispersion of 210 mg/L, during the grafting process, were able to remove, approximately, 45 % of a mixture of parabens (1 mg/L) after one use. In contrast, during subsequent uses, an approximate value of 35 % removal was achieved, showing the stability of the material after several cycles of use.