Poly(vinylidene fluoride) membrane with immobilized TiO for degradation of steroid hormone micropollutants in a photocatalytic membrane reactor.

The lack of effective technologies to remove steroid hormones (SHs) from aquatic systems is a critical issue for both environment and public health. The performance of a flow-through photocatalytic membrane reactor (PMR) with TiO immobilized on a photostable poly(vinylidene fluoride) membrane (PVDF-TiO) was evaluated in the context of SHs degradation at concentrations from 0.05 to 1000 µg/L under UV exposure (365 nm). A comprehensive investigation into the membrane preparation approach, including varying the surface Ti content and distribution, and membrane pore size, was conducted to gain insights on the rate-limiting steps for the SHs degradation. Increasing surface Ti content from 4 % to 6.5 % enhanced the 17β-estradiol (E2) degradation from 46 ± 12-81 ± 6 %. Apparent degradation kinetics were independent of both TiO homogeneity and membrane pore size (0.1-0.45 µm). With optimized conditions, E2 removal was higher than 96 % at environmentally relevant feed concentration (100 ng/L), a flux of 60 L/mh, 25 mW/cm, and 6.5 % Ti. These results indicated that the E2 degradation on the PVDF-TiO membrane was limited by the catalyst content and light penetration depth. Further exploration of novel TiO immobilization approach that can offer a larger catalyst content and light penetration is required to improve the micropollutant removal efficiency in PMR.