可见光激发下模拟海水中四环素光降解的机制和路径

为了探明海水体系中多相光催化降解污染物的机制和路径，研究了在可见光激发下不同介孔TiO₂光催化降解纯水和模拟海水中四环素(TC)的过程，明确了不同盐离子对光催化降解过程的影响.结合自由基捕获实验，电子自旋共振(ESR)光谱和中间产物分析研究了光降解污染物的主要活性物种和模拟海水中TC降解途径.结果表明，模拟海水中TC光催化过程会受到显著抑制，手性介孔TiO₂催化剂对TC光降解反应速率相比其在纯水体系降低了70%左右，而非手性TiO₂光催化剂在海水体系中几乎不能降解TC.模拟海水中阴离子对光降解过程影响较小，但Mg²⁺和Ca²⁺存在会显著抑制光催化过程.无论在纯水还是模拟海水中，可见光激发后催化剂产生的活性物种都是空穴为主，因此模拟海水中降解路径与纯水体系中相同.盐离子不会抑制活性物种的产生，但Mg²⁺和Ca²⁺会富集在TC分子中电负性强的原子周边，阻碍空穴等对TC分子中电负性强原子的攻击，从而抑制了光催化降解效率.

Photo-Degradation Mechanism and Pathway for Tetracycline in Simulated Seawater Under Irradiation of Visible Light

To explore the mechanism and pathway for pollutant degradation in seawater by heterogeneous photocatalysts, the degradation of tetracycline (TC) in pure water and simulated seawater with different mesoporous TiO₂ under the excitation of visible light was first investigated; then the effect of different salt ions on the photocatalytic degradation process was clarified. Combined with radical trapping experiments, electron spin resonance (ESR) spectroscopy, and intermediate product analysis, the main active species for photodegrading pollutants and the pathway of TC degradation in simulated seawater were investigated. The results showed that the photodegradation for TC in simulated seawater was significantly inhibited. Compared with the TC photodegradation in pure water, the reaction rate of the chiral mesoporous TiO₂ photocatalyst for TC was reduced by approximately 70%, whereas the achiral mesoporous TiO₂ photocatalyst could hardly degrade TC in seawater. Anions in simulated seawater had little effect on photodegradation, but Mg²⁺ and Ca²⁺ ions significantly inhibited the TC photodegradation process. Whether in water or simulated seawater, the active species generated by the catalyst after excitation by visible light were mainly holes, and each salt ion did not inhibit the generation of active species; thus, the degradation pathway both in simulated seawater and in water was the same. However, Mg²⁺ and Ca²⁺ would be enriched around the highly electronegative atoms in TC molecules, hindering the attack of holes to highly electronegative atoms in TC molecules, thereby inhibiting the photocatalytic degradation efficiency.