Mai Jiaxing, Sun Weiling, Xiong Lin, Liu Ying, Ni Jinren
Department of Environmental Engineering, Peking University, Beijing 100871, China.
Chemosphere. 2008 Sep;73(4):600-6. doi: 10.1016/j.chemosphere.2008.05.073. Epub 2008 Jul 26.
Photocatalytic degradation of 17beta-estradiol (E2) in aqueous medium mediated with titanium dioxide (TiO2) was studied. Moreover, effect of TiO2 dosage on the degradation efficiency was investigated. Particular attention was paid to the identification of intermediates and analysis of photocatalytic degradation mechanism of E2 under neutral and alkaline conditions. The degradation efficiency of E2 increased with increasing concentration of TiO2 but decreased due to light scattering as TiO2 concentration was greater than 0.5mgml(-1). Several intermediates were formed during photocatalytic degradation of E2. However, only a few of the compounds could be identified and confirmed by LC-MS and LC-MS/MS. Six intermediates were observed by photocatalytic oxidation under alkaline conditions, namely 2-hydroxyestradiol, 10epsilon-17beta-dihydroxy-1,4-estradien-3-one (DEO), 10epsilon-hydroperoxide-17beta-hydroxy-1,4-estradien-3-one and three kinds of dicarboxylic acids formed by the opening of aromatic ring. In addition to the six intermediates mentioned above, 17beta-hydroxy-1,4-estradien-3-one (EO) was observed under neutral conditions and in the presence of methanol. Based on these intermediates, which were hardly degraded even after E2 was fully degraded, the mechanism of E2 degradation by TiO2 photocatalysis was elucidated.
研究了二氧化钛（TiO₂）介导的水介质中17β-雌二醇（E₂）的光催化降解。此外，还研究了TiO₂用量对降解效率的影响。特别关注了中性和碱性条件下E₂光催化降解中间体的鉴定及降解机理分析。E₂的降解效率随TiO₂浓度的增加而提高，但当TiO₂浓度大于0.5mg/ml⁻¹时，由于光散射作用降解效率降低。E₂光催化降解过程中形成了几种中间体。然而，只有少数化合物能够通过液相色谱-质谱联用（LC-MS）和液相色谱-串联质谱联用（LC-MS/MS）进行鉴定和确认。在碱性条件下光催化氧化观察到六种中间体，即2-羟基雌二醇、10ε-17β-二羟基-1,4-雌二烯-3-酮（DEO）、10ε-氢过氧化物-17β-羟基-1,4-雌二烯-3-酮以及由芳环开环形成的三种二羧酸。除上述六种中间体外，在中性条件及甲醇存在下观察到了17β-羟基-1,4-雌二烯-3-酮（EO）。基于这些即使在E₂完全降解后仍难以降解的中间体，阐明了TiO₂光催化降解E₂的机理。
