Chirukuri Rajasekharam, Atmakuru Ramesh
Department of Analytical Chemistry, International Institute of Biotechnology and Toxicology (IIBAT), Padappai, Kanchipuram District, Tamil Nadu 601301, India.
Department of Analytical Chemistry, International Institute of Biotechnology and Toxicology (IIBAT), Padappai, Kanchipuram District, Tamil Nadu 601301, India.
Chemosphere. 2015 Nov;138:932-9. doi: 10.1016/j.chemosphere.2014.12.029. Epub 2015 Jan 7.
The dissipation kinetics and the adsorption characteristics of bispyribac sodium, a pyrimidinyloxybenzoic herbicide, in 21 types of soil collected from different locations in the U.S., Italy, Spain, Greece, France, U.K., the Netherlands, Germany, and India were evaluated under laboratory conditions. The soil sorption study was conducted using the batch equilibrium process. The paper also investigated the adsorption efficiency of bispyribac sodium in the presence of different kinds of background electrolytes, surfactants, and different temperatures in two different soils. The results showed that the Freundlich equation fits its adsorption well, and the Freundlich adsorption constant values (Kf) ranged from 0.3 to 5.6 mL g(-1). Adsorption isotherms were nonlinear, with 1/nf values <1. Bispyribac sodium adsorption by two soils increased with increasing electrolytes concentration using CaCl2, KCl, NH4Cl, KH2PO4 and MgCl2 as a background electrolytes. The adsorption coefficient value decreased when anionic and nonionic surfactants were used at the three surfactant concentrations in two types of soil but increased with cationic surfactant, and temperature. Sorption was positively correlated with OM and negatively correlated with a soil pH of 5.0 to 8.1. The free energy (ΔG) values of bispyribac sodium in the soils were less than 40 kJ mol(-1) and negative values were obtained. This indicates that the adsorption of bispyribac sodium is mainly a physical and spontaneous process. The GUS values were less than 2.9 in all the soil types studied, and the residues of bispyribac sodium were low to moderate to leacher (mobile) in the soil.
在实验室条件下，评估了嘧啶氧基苯甲酸类除草剂双草醚钠在美国、意大利、西班牙、希腊、法国、英国、荷兰、德国和印度不同地点采集的21种土壤中的消解动力学和吸附特性。土壤吸附研究采用批量平衡法进行。本文还研究了在两种不同土壤中，不同种类的背景电解质、表面活性剂和不同温度存在下双草醚钠的吸附效率。结果表明，Freundlich方程能很好地拟合其吸附过程，Freundlich吸附常数（Kf）值范围为0.3至5.6 mL g(-1)。吸附等温线为非线性，1/nf值<1。以CaCl2、KCl、NH4Cl、KH2PO4和MgCl2作为背景电解质，两种土壤对双草醚钠的吸附随电解质浓度增加而增加。在两种土壤中，三种表面活性剂浓度下使用阴离子和非离子表面活性剂时，吸附系数值降低，但使用阳离子表面活性剂时吸附系数值增加，且吸附随温度升高而增加。吸附与有机物质呈正相关，与土壤pH值在5.0至8.1之间呈负相关。双草醚钠在土壤中的自由能（ΔG）值小于40 kJ mol(-1)，且为负值。这表明双草醚钠的吸附主要是一个物理和自发过程。在所研究的所有土壤类型中，GUS值均小于2.9，双草醚钠在土壤中的残留对淋溶（移动）来说处于低到中等水平。
