Adsorption–desorption behavior of atrazine on agricultural soils in China
Lin Yue , ChengJun Ge , Huamei Yu , Hui Deng , Bomin Fu
DOI:10.1016/j.jes.2016.11.002
Received September 06, 2016,Revised September 28, 2016, Accepted November 11, 2016, Available online November 19, 2016
Volume 29,2017,Pages 180-189
Adsorptionanddesorptionareimportantprocessesthataffectatrazinetransport,transformation,andbioavailabilityinsoils.Inthisstudy,theadsorption–desorptioncharacteristicsofatrazinein three soils (laterite, paddy soil and alluvial soil) were evaluated using the batch equilibrium method. The results showed that the kinetics of atrazine in soils was completed in two steps: a “fast” adsorption and a “slow” adsorption and could be well described by pseudo-second-order model.In addition,the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models. It was found that the adsorption data on laterite, and paddy soil were better fitted by the Freundlich model;as for alluvial soil,the Langmuir model described it better. The maximum atrazine sorption capacities ranked as follows: paddy soil > alluvial
soil > laterite. Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic. The desorption data showed that negative hysteresis occurred. Furthermore, lower solution pH value was conducive to the adsorptionofatrazineinsoils.Theatrazineadsorptioninthesethreetestedsoilswascontrolled by physical adsorption, including partition and surface adsorption. At lower equilibrium concentration, the atrazine adsorption process in soils was dominated by surface adsorption;while with the increase of equilibrium concentration, partition was predominant.
