Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
College of Environmental Science and Engineering, Southwest Forestry University, Kunming 650224, China.
Sci Total Environ. 2014 May 15;481:209-16. doi: 10.1016/j.scitotenv.2014.02.041. Epub 2014 Mar 2.
Various mechanisms play roles simultaneously for antibiotic sorption on solid particles. Previous studies simply emphasized mechanisms that match the increased or decreased antibiotic sorption by metal ions, without a general concept including these diverse mechanisms in their co-sorption. We observed both increased and decreased OFL and Cu(II) sorption in their co-sorption system. The comparison of the sorption coefficients of primary adsorbate (Kd(pri)) and co-adsorbate (Kd(co)) suggested that enhanced sorption occurred at high Kd(pri) region (low primary adsorbate concentration). Competitive sorption was observed when Kd(pri) was decreased to a certain value depending on solid particle properties. We thus summarized that if the adsorbates were introduced with low concentrations, OFL (such as hydrophobic region in solid particles) and Cu(II) (such as inner-sphere complexation sites) occupied their unique high-energy sorption sites. Cu(II) complexed with the adsorbed OFL, and OFL bridged by the adsorbed Cu(II) promoted the sorption for both chemicals. With the increased concentrations, the adsorbates spread to some common sorption sites with low sorption energy, such as cation exchange and electrostatic attraction region. The overlapping of Cu(II) and OFL on these sorption sites resulted in competitive sorption at high concentrations. The previously reported apparently increased or decreased sorption in antibiotic-metal ion co-sorption system may be only a part of the whole picture. Extended study on the turning point of decreased and increased sorption relating to water chemistry conditions and solid particle properties will provide more useful information to predict antibiotic-metal ion co-sorption.
各种机制同时在抗生素在固体颗粒上的吸附中发挥作用。先前的研究简单地强调了与金属离子引起的抗生素吸附增加或减少相匹配的机制，而没有将这些不同的机制包括在共同吸附中的一般概念。我们观察到在共吸附体系中，OFL 和 Cu(II) 的吸附都增加和减少。与主要吸附物（Kd（pri））和共吸附物（Kd（co））的吸附系数的比较表明，在高 Kd（pri）区域（低主要吸附物浓度）发生了增强的吸附。当 Kd（pri）取决于固体颗粒性质降低到一定值时，观察到竞争吸附。因此，我们总结出，如果吸附物以低浓度引入，则 OFL（如固体颗粒中的疏水区）和 Cu(II)（如内球络合位点）占据其独特的高能吸附位点。Cu(II)与吸附的 OFL 络合，吸附的 Cu(II)桥接的 OFL 促进了两种化学物质的吸附。随着浓度的增加，吸附物扩散到一些具有低吸附能的常见吸附位点，如阳离子交换和静电吸引区域。在这些吸附位点上，Cu(II) 和 OFL 的重叠导致在高浓度下的竞争吸附。先前报道的抗生素-金属离子共吸附系统中吸附增加或减少的明显现象可能只是整个情况的一部分。关于与水化学条件和固体颗粒性质有关的吸附减少和增加转折点的扩展研究将为预测抗生素-金属离子共吸附提供更有用的信息。
