State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
J Colloid Interface Sci. 2012 Apr 15;372(1):141-7. doi: 10.1016/j.jcis.2012.01.016. Epub 2012 Jan 17.
Enrofloxacin (ENR) occurs widely in natural waters because of its extensive use as a veterinary chemotherapeutic agent. To improve our understanding of the interaction of this emerging contaminant with soils and sediments, sorption of ENR on homoionic smectites and kaolinite was studied as a function of pH, ionic strength, exchangeable cations, and humic acid concentration. Batch experiments and in situ ATR-FTIR analysis suggested multiple sorption mechanisms. Cation exchange was a major contributor to the sorption of cationic ENR species on smectite. The decreased ENR sorption with increasing ionic strength indicated the formation of outer-sphere complexes. Exchangeable cations significantly influenced the sorption capacity, and the observed order was Cs<Ca<K. The peak shifts of the COO(-) stretch, coupled CO stretch and OH deformation, and the result of irreversible desorption FTIR spectra indicated that OH of the carboxyl group was involved in the formation of inner-sphere surface complexes. The XRD analysis confirmed that interlayer intercalation is an important contributor to ENR sorption, while humic acid had a negligible contribution to the interlayer intercalation. The results of this study provide new insight into the molecular mechanisms of ENR sorption on clay minerals.
恩诺沙星（ENR）由于作为兽医化学治疗剂的广泛使用而在天然水中广泛存在。为了提高我们对这种新兴污染物与土壤和沉积物相互作用的理解，研究了 ENR 在同晶型蒙脱石和高岭石上的吸附，作为 pH、离子强度、可交换阳离子和腐殖酸浓度的函数。批量实验和原位 ATR-FTIR 分析表明存在多种吸附机制。阳离子交换是带正电荷的 ENR 物种在蒙脱石上吸附的主要贡献者。随着离子强度的增加，ENR 的吸附减少表明形成了外配位络合物。可交换阳离子显著影响了吸附容量，观察到的顺序为 Cs<Ca<K。COO(-)伸展、耦合 CO 伸展和 OH 变形的峰位移以及不可逆解吸 FTIR 光谱的结果表明，羧基的 OH 参与了内配位表面络合物的形成。XRD 分析证实层间插层是 ENR 吸附的重要贡献者，而腐殖酸对层间插层的贡献可以忽略不计。这项研究的结果提供了对粘土矿物上 ENR 吸附分子机制的新见解。
