Photocatalytic degradation of pharmaceuticals from water using nitrogen-doped titanium dioxide coated on fiberglass cloth

Abstract

Caffeine, carbamazepine, and ibuprofen are pharmaceuticals that were frequently found in natural water, and they can pose a potential threat to aquatic organisms even at low concentrations. Visible light-driven photocatalysis is a green technology that can remove pharmaceuticals from water, and the treated water could be useful for other purposes. The recycling of wastewater is a sustainable option for water management. In this study, the photocatalysts were prepared by the binder-free coating of commercial anatase TiO2 and sol-gel-derived nitrogen-doped TiO2 (moles N/Ti of 1–5) on fiberglass clothes (FGC). Nitrogen was found to be interstitially doped into TiO2 and improved the photocatalytic activity of TiO2 under visible light irradiation. The molar ratio of N/Ti for coating on FGC was optimized through the removal of caffeine in a simple batch reactor. 3N–TiO2-coated FGC (N/Ti molar ratio = 3) was optimum photocatalyst. The curtain waterfall reactor was fabricated to efficiently utilize the energy from visible light source. The 3N–TiO2-coated FGC was used in a curtain waterfall reactor to remove caffeine, carbamazepine, and ibuprofen from the water. The removal efficiencies achieved their acceptable levels for reuse within an irradiation time of 14 h. Total organic carbon results confirmed the mineralization of pharmaceuticals. The photocatalyst can be reused for five cycles (12 h for each cycle) with stable performance although it was kept as a roll before use, which indicates the convenience to transport to the place of use, and the potential to further fit in various shapes of the photocatalytic reactor.