Surface complexation of the zwitterionic fluoroquinolone antibiotic ofloxacin to nano-anatase TiO2 photocatalyst surfaces.
Surface complexation of the zwitterionic fluoroquinolone antibiotic ofloxacin to nano-anatase TiO2 photocatalyst surfaces.
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DOI：
10.1021/es302097k
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发表时间：
2012-10
影响因子：
11.4
通讯作者：
T. Paul;M. Machesky;T. Strathmann
中科院分区：
文献类型：
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作者：
T. Paul;M. Machesky;T. Strathmann
研究了两性离子氟喹诺酮类抗生素氧氟沙星（OFX）与纳米锐钛矿二氧化钛（TiO(2)）的表面络合行为。OFX在水相TiO(2)悬浮液中的吸附被测量为pH、OFX浓度、电解质类型和浓度的函数，并从原位光谱观察中获得结构信息。OFX吸附后紫外可见光谱红移表明球内配位配合物的形成。TiO(2)吸附OFX的傅里叶变换红外光谱在很宽的浓度和pH范围内是不变的，并且与羧酸基去质子化的溶解物质的测量光谱相似。建立了一个受光谱观测约束的电荷分布表面络合模型来描述宏观吸附趋势。三叉齿吸附模式包括去质子化羧酸基团的桥接双齿内球配位和通过喹啉环上相邻羰基的氢键，成功地预测了观察到的吸附趋势。在NaClO(4)电解质中，光谱数据和模型拟合表明，在酸性条件下，OFX离子与ClO(4)（-）的配对增强了吸附。此外，将OFX吸附数据与可见光（λ > 400 nm）光催化降解动力学中的pH趋势进行比较，表明吸附的OFX- clo(4)（-）离子对抑制了OFX的光降解。
The surface complexation behavior of ofloxacin (OFX), a zwitterionic fluoroquinolone antibiotic, to nano-anatase titanium dioxide (TiO(2)) was characterized. OFX adsorption in aqueous TiO(2) suspensions was measured as a function of pH, OFX concentration, and electrolyte type and concentration, and structural information was derived from in situ spectroscopic observations. An ultraviolet-visible spectral red shift upon OFX adsorption indicated formation of inner-sphere coordination complexes. Fourier transform infrared spectra of TiO(2)-adsorbed OFX were invariable over a wide concentration and pH range and were similar to measured spectra of dissolved species wherein the carboxylate group is deprotonated. A charge distribution surface complexation model constrained by spectroscopic observations was developed to describe macroscopic adsorption trends. A tridentate mode of adsorption involving bridging bidentate inner-sphere coordination of the deprotonated carboxylate group and hydrogen bonding through the adjacent carbonyl group on the quinoline ring resulted in successful predictions of observed adsorption trends. In NaClO(4) electrolyte, spectroscopic data and model fitting suggested that OFX ion pairing with ClO(4)(-) enhanced adsorption under acidic conditions. Moreover, comparison of OFX adsorption data with the pH trend in the kinetics of OFX degradation by visible light (λ > 400 nm) photocatalysis suggested that adsorbed OFX-ClO(4)(-) ion pairs inhibit photodegradation.