State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
Chemosphere. 2013 Sep;93(1):1-8. doi: 10.1016/j.chemosphere.2013.04.043. Epub 2013 May 23.
Photodegradation of tetracycline (TC) was investigated in aqueous solution by visible-light-driven photocatalyst Sr-doped β-Bi2O3 (Sr-Bi2O3) prepared via solvothermal synthesis. The decomposition of TC by Sr-Bi2O3 under visible light (λ>420nm) irradiation followed pseudo-first-order kinetics, and the removal ratio reached 91.2% after 120min of irradiation. Sr-Bi2O3 photocatalysis is able to break the naphthol ring of TC which decomposes to m-cresol via dislodging hydroxyl group step by step by photogenerated electron. This mechanism was verified by electron spin resonance measurement, the addition of radical scavengers and the intermediate product analysis, indicating that the photogenerated electron acts as a reductant and can be the key to the degradation process. In contrast, in TiO2 photocatalysis the naphthol ring is broken via oxidation by hydroxyl radical, while in direct photolysis the ring remains intact. In addition, the toxicity of photodegradation products was analyzed by bioluminescence inhibition. After 120min of irradiation by Sr-Bi2O3, the toxicity decreases by 90.6%, which is more substantial than direct photolysis (70%) and TiO2 photocatalysis (80%), indicating that the Sr-Bi2O3 photocatalysis is more eco-friendly than the other two methods.
采用溶剂热法制备了 Sr 掺杂的β-Bi2O3（Sr-Bi2O3）可见光驱动光催化剂，研究了其在水溶液中对四环素（TC）的光降解性能。Sr-Bi2O3 在可见光（λ>420nm）照射下对 TC 的分解遵循准一级动力学，照射 120min 后去除率达到 91.2%。Sr-Bi2O3 光催化能够通过光生电子逐步将 TC 的萘环断开，通过逐出羟基基团将其分解为间甲酚。该机理通过电子顺磁共振测量、自由基清除剂的添加和中间产物分析得到验证，表明光生电子作为还原剂起作用，是降解过程的关键。相比之下，在 TiO2 光催化中，萘环通过羟基自由基的氧化作用断裂，而在直接光解中，环保持完整。此外，通过生物发光抑制分析了光降解产物的毒性。Sr-Bi2O3 照射 120min 后，毒性降低了 90.6%，这比直接光解（70%）和 TiO2 光催化（80%）更显著，表明 Sr-Bi2O3 光催化比其他两种方法更环保。
