Photocatalytic decomposition of perfluorooctanoic acid in pure water and sewage water by nanostructured gallium oxide

Abstract

Due to its global occurrence and environmental persistence, perfluorooctanoic acid (PFOA) has attracted worldwide concerns including its decomposition method. The nanostructured β-Ga2O3 with a novel sheaf-like structure was synthesized via a PVA-assisted hydrothermal method and subsequent heat treatment. The sheaf-like Ga2O3 was self-assembled from nanoplates, possessing a high value of specific surface area (36.1 m2/g) and a large number of nanopores (2–4 nm and 8 nm). Sheaf-like Ga2O3 exhibited a remarkable photocatalytic activity for PFOA decomposition in pure water under 254 nm UV irradiation with the rate constant of 4.85 h−1, which was 16 and 44 times higher than that of commercial Ga2O3 and P25 respectively. This can be attributed to the close bonding between PFOA and Ga2O3, and nanoporous structure of sheaf-like Ga2O3. In addition, in combination of 185 nm vacuum UV irradiation, the sheaf-like Ga2O3 showed high efficiency to remove trace PFOA in the secondary effluent of sewage, in which the decomposition of targeted trace pollutants such as PFOA is generally inhibited by coexisting high-level natural organic matters and bicarbonate.