纳米粘土矿物对阿特拉津的吸附-解吸特性研究

采用批量平衡实验，研究了纳米粘土矿物与原粘土矿物对除草剂阿特拉津的吸附解吸特陛。结果表明，粘土矿物对阿特拉津的吸附-解吸均能用Freundlich方程很好地拟合。随着溶液中阿特拉津浓度的增加，粘土矿物对阿特拉津的吸附量增加；粘土矿物粒径越小，吸附量越大，纳米粘土矿物的吸附量显著大于原粘土矿物。粘土矿物对阿特拉津吸附量大小顺序为：纳米SiO2）纳米蒙脱石〉凹凸棒石〉蒙脱石〉SiO2。粘土矿物对阿特拉津的解吸表现出一定的滞后效应，即粘土矿物吸附的阿特拉津越多，解吸的越少。粘土矿物对阿特拉津的解吸率大小顺序为：SiO2〉凹凸棒石〉纳米蒙脱石〉纳米SiO2〉蒙脱石。

Adsorption and Desorption of Atrazine on Nanoscale Clay Minerals

Adsorption and desorption of atrazine on clay minerals were studied using the batch equilibration technique. Adsorption isotherms of atrazine conformed to the Freundlich equation. Adsorption of atrazine on clay minerals increased with increasing concentration. The smaller the particle size of clay minerals, the more the adsorption of atrazine. The nanoscale clay minerals had higher adsorption capacity for atrazine than those of the corresponding clays. The adsorption capacity of clay minerals for atrazine followed the order nano-SiO2 〉 nano-montmorillonite 〉 attapulgite 〉 montmorillonite 〉 SiO2. Desorption studies were conducted by repeated replacement of 10 mL of the supernatant equilibrium solutions after adsorption, with 0.01 mol-L^-1 CaCl2. Desorption isotherms also conformed to Freundlich equation but Kf values was higher than that for adsorption and increased with increase in initially adsorbed concentration of atrazine. Desorption of atrazine showed significant hystersis which was indicated by the higher adsorption slope （1/ads） compared to the desorption slope （1/ads）. The desorption rate followed the order SiO2 〉 attapulgite 〉 nano-montmorillonite 〉 nano-SiO2 〉 montmorillonite.