Solvothermal synthesis of C–N codoped TiO2 and photocatalytic evaluation for bisphenol A degradation using a visible-light irradiated LED photoreactor

Abstract

In this study, a highly visible-light photoactive carbon and nitrogen codoped TiO2 (CN-TiO2) was synthesized via a facile solvothermal method. The conditions for each synthesis step including selection of dopants, solvothermal treatment, and calcination temperatures were evaluated. X-ray photoelectron spectroscopy shows that the surface of TiO2 was modified by carbon and nitrogen via formation of Ti–C bonds, carbonate species and oxynitrides. The derived photocatalyst is predominantly of anatase phase, with well-developed mesoporosity and a large BET surface area (102m2/g). The photocatalytic degradation (PCD) of bisphenol A (BPA) by CN-TiO2 was evaluated using a novel photoreactor irradiated with flexible strips of visible light-emitting diode (Vis-LED). The PCD of BPA was most favorable under circumneutral pH. Under 5h of irradiation with white, blue, green and yellow LED lights, the extents of BPA degradation were >99%, >99%, 84% and 24% respectively, while the corresponding percentages of mineralization were 70%, 60%, 45% and 9%. Presence of sulfate, chloride and nitrate at 5.0mM only slightly retarded BPA degradation, while bicarbonate and silica inhibited the process to a much larger extent. Deactivation of the CN-TiO2 by silica could be attributed to the formation of surface-bound silica species. By adjusting to acidic condition, the detrimental effect from silica could be significantly suppressed.