蒙脱石对喹诺酮类抗生素的吸附平衡及动力学特征

以蒙脱石为吸附剂进行水中2种喹诺酮类抗生素（环丙沙星和诺氟沙星）的静态吸附试验，考察初始浓度、pH值和阳离子强度对吸附性能的影响.结果表明，蒙脱石对环丙沙星和诺氟沙星的吸附过程均符合二级反应动力学方程，吸附速率常数分别为0.063和0.024 kg·mg-1·h-1环丙沙星和诺氟沙星的吸附等温线均能较好地符合Freundlich方程，且lgKf值较大，具有较强的吸附能力.当溶液pH值小于环丙沙星和诺氟沙星的pKa2值时，具有较高吸附量；大于pKa2值时，吸附量急剧下降.环丙沙星和诺氟沙星阳离子以及兼性离子均可被蒙脱石吸附，在高pH值条件下，阴离子与蒙脱石表面络合可能是蒙脱石吸附去除环丙沙星和诺氟沙星的主要作用机制.Ca2+对吸附有重要影响，其浓度越高，环丙沙星和诺氟沙星的吸附量越低.

Adsorption Equilibrium and Kinetics of Quinolone Antibiotics on Montmorillonite

A static adsorption experiment was carried out to investigate the influence of initial concentration, pH, and cationic strength on adsorption of two kinds of quinolone antibiotics (ciprofloxacin and norfloxacin) on montmorillonite.The results showed that the adsorption process of ciprofloxacin and norfloxacin were consistent with pseudo-second-order kinetics, and the adsorption rate constants were 0.063 and 0.024 kg·mg-1·h-1 respectively.Adsorption isotherms were well described by Freundlich equation, and the high lgKf showed strong adsorption ability.When the solution pH was less than the pKa2 of ciprofloxacin and norfloxacin, the adsorption capacity was higher.The adsorption capacity decreased sharply when the solution pH was above the pKa2.Both cationic and zwitterionic forms of ciprofloxacin and norfloxacin could be adsorbed significantly.At higher pH, the complexation of anion on the montmorillonite surface might become the main mechanism.The concentration of Ca2+ had a great influence on adsorption.The higher the concentration, the lower the adsorption capacity of ciprofloxacin and norfloxacin.