School of Water Resources and Environment, and Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, PR China.
School of Water Resources and Environment, and Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, PR China.
Chemosphere. 2014 Sep;111:283-90. doi: 10.1016/j.chemosphere.2014.04.032. Epub 2014 May 13.
Interaction between various compounds in natural systems may influence the adsorption of these species and their environmental fate. In this work, we studied the interactions between a widely used antibiotic levofloxacin (LEV) and phosphate at the surface of goethite (α-FeOOH), which was important to better understand the competitive adsorption of antibiotics and oxyanions in natural systems. The presence of phosphate decreased LEV adsorption to goethite significantly over the whole pH range. The other way around, LEV had a little influence on phosphate adsorption. Eight types of LEV-goethite complexes were proposed and modeled in our study. Electrostatic competition was the main reason for the competition of binary components (LEV and phosphate) to goethite surface. Adsorption of single component (LEV or phosphate) to goethite was well predicted using the CD-MUSIC (Charge Distribution Multi-Site Complexation) model. In competition experiments, phosphate adsorption was still predicted well, but LEV adsorption was overestimated in model calculations. This is because less negative charge of LEV is located at outer electrostatic plane in our study, which decreases their electrostatic competition to goethite surface.
在自然体系中，各种化合物之间的相互作用可能会影响这些物质的吸附及其环境归宿。在这项工作中，我们研究了在针铁矿（α-FeOOH）表面上广泛使用的抗生素左氧氟沙星（LEV）和磷酸盐之间的相互作用，这对于更好地理解抗生素和含氧阴离子在自然体系中的竞争吸附很重要。在整个 pH 范围内，磷酸盐的存在显著降低了 LEV 在针铁矿上的吸附。相反，LEV 对磷酸盐的吸附影响很小。在我们的研究中，提出并模拟了 8 种 LEV-针铁矿配合物。静电竞争是二元组分（LEV 和磷酸盐）与针铁矿表面竞争的主要原因。使用 CD-MUSIC（电荷分布多位点络合）模型可以很好地预测单一组分（LEV 或磷酸盐）在针铁矿上的吸附。在竞争实验中，磷酸盐的吸附仍能很好地预测，但在模型计算中，LEV 的吸附被高估了。这是因为在我们的研究中，LEV 的负电荷较少位于外静电平面上，这降低了它们与针铁矿表面的静电竞争。
