Photodegradation of Bisphenol a in Water via Round-the-Clock Visible Light Driven Dual Layer Hollow Fiber Membrane

Abstract

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) that can cause adverse effects on human health. The incorporation of materials as visible light photocatalysts and its energy storage capability allow for the photodegradation of BPA, especially in the absence of a light source. To date, there have been no significant studies regarding energy storage in membrane technology, with only a focus on the suspension form. Hence, this study was conducted to degrade the pollutant through a co-extrusion process using a mixture of copper (II) oxide and tungsten oxide as the photocatalyst and energy storage materials, respectively. Both materials were embedded into polyvinylidene (PVDF) membranes to produce a Cu2O/WO3/PVDF dual-layer hollow fiber (DLHF) membrane. The outer dope extrusion flow rate was set at 3 mL/min, 6 mL/min, and 9 mL/min with photocatalyst:polymer ratios of 0.3, 0.50, and 0.7 Cu2O/WO3/PVDF, respectively. The performance of the membranes for each ratio was evaluated using 2 ppm of BPA with visible light irradiation. The results showed that each membrane’s outer and inner layers featured finger-like void structures, while the intermediate part had a sponge-like structure. The membrane with the photocatalyst:polymer ratio of 0.5 was hydrophilic and had a high porosity of 54.97%, resulting in a high flow of 510 L/m2h. Under visible light irradiation, a 0.5 Cu2O/PVDF DLHF membrane with a 6-mL/min outer dope flow rate was able to remove 97.82% of 2-ppm BPA without copper leaching into the water sample. Under dark conditions, the DLHF sample showed the capability of energy storage performance and could drive certain degradation after lighting off up to 70.73% of 2-ppm BPA. The photocatalytic DLHF membrane with the ratio of 0.5 was the most optimal due to its potential morphology and ability to degrade a large amount of BPA. It is important to emphasize that usage of materials with the capability for energy storage can provide a significant contribution toward more practical membranes, so photodegradation can occur even in dark conditions.