Qian Sheng, Zhu Heng, Xiong Bailian, Zheng Guocan, Zhang Jinzhong, Xu Weihong
College of Resources and Environment, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Southwest University, Chongqing, 400715, People's Republic of China.
Department of Resources and Environment, Zunyi Normal College, Zunyi, Guizhou, 563002, People's Republic of China.
Environ Sci Pollut Res Int. 2017 Apr;24(12):11493-11503. doi: 10.1007/s11356-017-8800-4. Epub 2017 Mar 18.
Endosulfan is an organochlorine pesticide widely used in Southwest China. In this paper, the adsorption and desorption characteristics of endosulfan in two typical agricultural soils (latosol and lateritic red soil) in this area were studied. The results showed that Langmuir isothermal equation could well describe the adsorption thermodynamic characteristics of endosulfan in latosol and lateritic red soil, and the maximum adsorption capacities of α-endosulfan were 0.186 and 0.209 mg/g, while those of β-endosulfan were 0.140 and 0.148 mg/g, respectively. Endosulfan adsorption in the two soils was an exothermic physicochemical process, but dominated by physical process. The adsorption kinetic characteristics of endosulfan in the two soils could be well described by second-order kinetic equation, and the initial rate constants were 0.228 and 0.325 mg/(g min) for α-endosulfan, while those were 0.119 and 0.125 mg/(g min) for β-endosulfan, respectively. The adsorbed endosulfan in the two soils was difficult to be desorbed into the liquid phase, and showed weak desorption hysteresis. These results implied that endosulfan could be firmly adsorbed by the two soils, and their adsorption and desorption abilities may be related to the contents of soil clay and organic matter.
硫丹是一种在中国西南地区广泛使用的有机氯农药。本文研究了该地区两种典型农业土壤（砖红壤和赤红壤）中硫丹的吸附和解吸特性。结果表明，Langmuir等温方程能很好地描述硫丹在砖红壤和赤红壤中的吸附热力学特征，α-硫丹的最大吸附量分别为0.186和0.209 mg/g，β-硫丹的最大吸附量分别为0.140和0.148 mg/g。硫丹在这两种土壤中的吸附是一个放热的物理化学过程，但以物理过程为主。硫丹在这两种土壤中的吸附动力学特征能用二级动力学方程很好地描述，α-硫丹的初始速率常数分别为0.228和0.325 mg/(g·min)，β-硫丹的初始速率常数分别为0.119和0.125 mg/(g·min)。两种土壤中吸附的硫丹难以解吸进入液相，表现出较弱的解吸滞后现象。这些结果表明，硫丹能被这两种土壤牢固吸附，其吸附和解吸能力可能与土壤黏土和有机质含量有关。
