Free standing titanium dioxide hollow nanofibers for photocatalytic degradation of bisphenol A

Abstract

Modernization and urbanization have adversely affected water quality and harmed the sustainability of water sources. Bisphenol A (BPA) has been identified as an endocrine-disrupting compound that, when exposed to the human body, can interfere with the hormone system and cause severe health effects and disorders. Titanium dioxide (TiO2), a prevalently used semiconductor in photocatalytic degradation fields, has wide bandgap energy and a low specific surface area. These properties can lead to a decline in photocatalytic degradation performance. The template synthesis approach can be used to produce hollow nanofibers photocatalysts with a large surface area, a narrow bandgap, and excellent degradation capability. This process, however, yields powder-form photocatalysts that require post-recovery treatment before being recycled in a photocatalytic slurry system. In this study, TiO2 hollow nanofibers (THNFs) were developed at various calcination temperatures. THNFs produced at 600 °C (THNF600) produced nanofibers with the best hollow morphology, with a bandgap of 3.0 eV, with a specific surface area of 81.2776 m2/g, and mixed-phase of 24.2 % anatase and 75.8 % rutile. As a result of the large surface area and excellent optical properties, the THNFs exhibited the highest BPA degradation of 71.48%. This result was also significantly better than that of Degussa P25, a commercial TiO2, with BPA degrades at only 38.62%. Using THNF600, the optimum photocatalysts dosage, pH, and initial BPA concentration were determined to be 0.75 g/L, pH 4.1, and 10 ppm, respectively. Then, the powderform THNF600 was assembled into a free-standing form using chemical treatment and vacuum filtration technique. Free-standing THNFs containing 0.75 g of THNF600 (FS75-THNFs) exhibited good adherence and connectivity between the nanofibers. After five cycles of reaction, the THNF600 experienced an average of 14.38% catalyst loss. The recyclability of FS75-THNFs outperformed the THNF600 which gave 5% average catalyst loss from its original weight while maintaining excellent degradation performance. In conclusion, this study recommends the potential application of freestanding TiO2 hollow nanofibers as the high potential novel photocatalysts for the treatment of BPA in wastewater.