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

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 (102 m(2)/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 5 h 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 5.0 mM 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. (C) 2010 Elsevier B.V. All rights reserved.