Enhanced photocatalytic oxidation of As(Ⅲ) by TiO2 modified with Fe3O4 through Ti－O－Fe interface bonds

Abstract

The treatment of arsenite pollution in water has always been concerned. Oxidation of high toxic As(III) to relatively low toxic As(V) by efficient photocatalytic oxidation technology is a research hotspot. This paper is focused on the active photocatalyst of TiO2 @Fe3O4 composites synthesized by a simple hydrothermal method for the efficient photocatalytic oxidation of As(Ⅲ). The successful construction of Ti–O–Fe interface bonds between TiO2 and Fe3O4 significantly promoted the transfer efficiency of photo-generated carriers, and further rapidly improved the photocatalytic oxidation efficiency of As(Ⅲ). The application results showed that the constructed TiO2 @Fe3O4 photocatalyst with 0.10 g Fe3O4 (TF-0.10) could complete the transformation from As(Ⅲ) (10,000 μg/L) to As(Ⅴ) within 4 min with a high oxidation ratio of 100% and maintained the good properties with unchanged crystal structure after five cycles. Furthermore, the photocatalytic properties of TiO2 @Fe3O4 composites were still stable under different pH values. Electron paramagnetic resonance (EPR) consequence displayed that the superoxide radical (‧O2—) and hole (h+) were the main intermediate product in the arsenic photocatalytic oxidation system, and hydroxyl radical (‧OH) had little effect on this oxidation system. The possible mechanism of As(Ⅲ) photocatalytic conversion was further explored based on the results of the data analysis. Furthermore, this work provides a potential new idea for the practicability of efficient photocatalytic arsenic oxidation.