Department of Soil and Water Science, University of Florida, Gainesville, FL 32611, United States.
J Hazard Mater. 2013 May 15;252-253:375-81. doi: 10.1016/j.jhazmat.2013.03.014. Epub 2013 Mar 15.
Emerging contaminant ciprofloxacin (CIP) has been frequently detected in soils. Its interactions with metals in soils remain largely unknown. We examined the effects of metal cations Cu and Ca and surface Fe/Al coating on CIP sorption by preloading Cu and Ca onto sand surface or mixing them with CIP in solution. Batch experiments with sand before and after removing Fe/Al coating on surface (coated and clean sand) were used. Based on Langmuir model and compared to clean sand, coated sand not only sorbed 10 times more CIP (50 mg kg(-1)) but also with 6 times stronger binding strength (1.95 L/μg). Though coated sand had limited Fe and Al on surface (157 and 904 mg kg(-1)), they were the major sites for CIP sorption probably via complexation with CIP's carboxyl group. Surface Fe/Al also played an important role in CIP sorption via Cu and Ca cation bridging as evidenced by increased CIP sorption with increasing Cu and Ca concentration preloaded onto sand surface. Different from Cu and Ca on the sand surface, Cu and Ca in solution decreased CIP sorption. Our results suggested that cations in soils could either facilitate or impede CIP sorption depending on they are on solid or solution phase.
新兴污染物环丙沙星（CIP）在土壤中频繁被检出。其与土壤中金属的相互作用仍知之甚少。我们研究了金属阳离子 Cu 和 Ca 以及表面 Fe/Al 涂层对 CIP 在土壤中吸附的影响，方法是将 Cu 和 Ca 预先加载到砂表面或在溶液中与 CIP 混合。使用了表面（涂覆和清洁砂）去除 Fe/Al 涂层前后的砂的批实验。基于 Langmuir 模型，与清洁砂相比，涂覆砂不仅吸附了 10 倍更多的 CIP（50mg/kg），而且结合强度也增强了 6 倍（1.95L/μg）。尽管涂覆砂表面的 Fe 和 Al 含量有限（157 和 904mg/kg），但它们是 CIP 吸附的主要位点，可能是通过与 CIP 的羧基络合。表面 Fe/Al 也通过 Cu 和 Ca 阳离子桥接在 CIP 吸附中发挥了重要作用，这可以通过将 Cu 和 Ca 预先加载到砂表面时增加 CIP 的吸附来证明。与砂表面的 Cu 和 Ca 不同，溶液中的 Cu 和 Ca 降低了 CIP 的吸附。我们的结果表明，土壤中的阳离子可以促进或阻碍 CIP 的吸附，具体取决于它们处于固相还是溶液相。
