纳米针状氧化镓光催化降解纯水和废水中全氟辛酸

采用聚乙烯醇调控的水热法合成了对全氟辛酸(PFOA)有高光催化活性的纳米针状Ga₂O₃.其颗粒长3-6μm,宽100-200nm,具有较大的比表面积(25.95m²/g)和纳米孔结构(4-25nm).在普通紫外光照射下(λ=254nm),纳米针状Ga₂O₃光催化降解纯水中PFOA的反应半衰期为18.2min,PFOA的一级反应降解动力学常数为2.28h^-1,分别为商品Ga₂O₃和TiO₂作为催化剂时的7.5和16.8倍.此外,当纳米针状Ga₂O₃与真空紫外光(λ=185nm)结合时,不仅可以更高效地降解纯水中的PFOA(反应速率常数4.03h^-1),而且能有效消除废水中共存有机物的影响,从而高效分解废水中的PFOA(反应速率常数3.51h^-1),且此方法的能耗远远低于文献报道的其他方法的能耗值.

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

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.