Photocatalytic decomposition of perfluorooctanoic acid in pure water and wastewater by needle-like nanostructured gallium oxide

Abstract

Nanostructured β-Ga2O3 with a needle-like structure was synthesized by a polyvinyl alcohol (PVA)-assisted hydrothermal method and subsequent heat treatment. It has a high specific surface area (25.95 m2/g) and large number of nanopores (4–25 nm), and it exhibited good photocatalytic activity for perfluorooctanoic acid (PFOA) decomposition in pure water unde UV irradiation (λ = 254 nm). PFOA had a half-life of 18.2 min, and the first order rate constant (2.28 h−1) for PFOA decomposition with the needle-like β-Ga2O3 was 7.5 and 16.8 times higher, respectively, than with commercial Ga2O3 and TiO2 (P25). In addition, in combination with vacuum UV (VUV) irradiation (λ = 185 nm), the needle-like β-Ga2O3 showed high activity for the removal of trace PFOA in both pure water and wastewater, with first order rate constants of 4.03 and 3.51 h−1, respectively. The adverse effect that coexisting natural organic matters in wastewater have on the decomposition of PFOA was mostly eliminated with VUV irradiation, and the energy consumption in this method was much less than the values reported for other methods in the literature.