畜禽养殖废水尾水中典型氟喹诺酮类抗生素的α-Fe2O3可见光催化降解机制研究

According to the widely use, veterinary antibiotics have entered aquatic environment with the effluent of the livestock wastewater, greatly threatening the ecological system and human health. Photocatalytic oxidation process possesses great potential on the treatment of antibiotic pollutants. The development of highly efficient visible-light driven photocatalysts and investigation of photodegradtion mechanism are of vital important. Hematite is applied in this study as photocatalyst to degrade fluoroquinolone antibiotics. The relationships between the exposed facets and the photocatalytic activity are focused by combining advanced characterization methods and calculations. Furthermore, the degradation kinetics is investigated through modelling study. Probable degradation pathway is proposed by analyzing degradation products with HPLC-QqQ-MS. The reactive oxygen species and degradation mechanism are specially focused by using ESR. This study would elucidate the conditions needed for the exposure of high index facets of α-Fe2O3 and the underlying photodegradation mechanism of fluoroquinolone antibiotics. Also, this study would provide new way and materials for the treatment of antibiotics in the effluent of the livestock wastewater. Finally, this study would deepen and expand the application of photocatalytic oxidation process in water pollution control.

兽用抗生素的大量滥用，导致其随畜禽养殖废水尾水进入水体等环境介质中，对自然生态系统及人类健康构成巨大威胁。光催化氧化工艺是抗生素类难降解污染物的一种极具潜力的处理工艺。其中，高效可见光催化剂开发及抗生素光催化降解机制研究至关重要。本课题拟以α-Fe2O3为光催化剂，研究其可见光催化降解典型氟喹诺酮类抗生素机制。交叉应用先进表征手段和模拟计算，重点揭示α-Fe2O3暴露晶面与其光催化活性的关系。进而通过模型拟合研究降解动力学特性；通过高效液相色谱-三重四极杆串联质谱检测降解中间产物从而推断降解途径。采用自由基捕获结合电子自旋共振波谱分析及自由基淬灭剂，重点剖析光催化降解机理。本研究有望阐明α-Fe2O3高指数晶面的可控暴露条件及对典型氟喹诺酮类抗生素的可见光催化降解机制，为畜禽养殖废水尾水中抗生素的治理提供新思路和新材料，为进一步加深和拓宽光催化氧化工艺在水污染控制领域的应用打下基础。

水体中残留抗生素会诱导抗生素抗性基因的传播和转移，给生态环境和人体健康造成潜在威胁。本项目以畜禽养殖废水尾水中典型残留抗生素（环丙沙星CIP、诺氟沙星NOR、磺胺嘧啶SDZ、四环素TTC）为研究对象，研究其在天然赤铁矿可见光催化体系中的降解特性，并对催化反应机制进行了深入探讨。实验结果表明，以天然赤铁矿为原料，在其表面进行AgBr/Ag3PO4负载改性，可以有效提高其光催化活性。通过设置不同Ag负载量，制备出Ag0.5BrPFe、Ag1BrPFe、Ag1.5BrPFe、Ag2BrPFe四种三相复合光催化材料。其中，Ag1.5BrPFe催化剂催化活性最强。在复合污染体系中，Ag1.5BrPFe对四种典型抗生素（环丙沙星CIP、诺氟沙星NOR、磺胺嘧啶SDZ、四环素TTC）具有较好的催化降解性能。四种抗生素降解速率由大到小依次为：SDZ > CIP ≈ NOR > TTC，降解速率的差异可能是由于其分子结构不同（电子密度不同），导致其与自由基的反应速率不同而引起的。酸性条件下，光催化降解速率较高；碱性条件下，降解过程受到明显抑制。光生空穴及超氧阴离子自由基是体系中的主要活性物种。基于前线理论计算（DFT），我们推测出了四种抗生素分子结构中可能被攻击的活性位点。以TTC为研究对象，我们进而通过HPLC-MS检测并推断出了可能的降解途径。