水悬浮剂中烷基酚聚氧乙烯醚在农药颗粒表面的吸附

采用高效液相色谱仪研究了水悬浮液中烷基酚聚氧乙烯醚（WitconolNP-100）在福美双和克百威两种农药颗粒表面的吸附性能，并探讨了表面活性剂在农药颗粒表面的吸附对悬浮种衣剂（FSC）的物理稳定性的影响．结果表明WitconolNP-100吸附等温线为Langmuir型．吸附受阴离子表面活性剂WitconolD-425影响，饱和吸附量在1-30g／l浓度范围内随其浓度增加而减小，并在20℃-54℃范围内随温度上升而增加．膨润土的引入增加了WitconolNP-100的吸附，并使其达饱和吸附需用量增加．54℃热贮稳定性试验表明，WitconolNP-100用量为10g/l，达到并接近饱和吸附值时，种衣剂产品分层率最小为5％．表明表面活性剂在农药颗粒表面形成完整的吸附层是悬浮种衣剂贮藏稳定的保证．

Adsorption of a Nonylphenol Ether on Pesticides Particles in Aqueous Suspensions

To examine the effect of surfactant adsorption on physical stability of flowable concentrates used for coating seeds (FSC) with pesticides, high performance liquid chromatography (HPLC) was used to analyze the adsorption of a surfactant (the nonylphenol ether, Witconol NP-100) on thiram and carbofuran particles. The adsorption isotherm for Witconol NP-100 on thiram and carbofuran was of the Langmuir type. Adsorption of Witconol NP-100 on pesticide particles decreased with increasing concentrations of the anionic surfactant, Morwet D-425, and increased at higher temperatures. Addition of bentonite increased the total adsorption but also increased the quantity of surfactant required. A storage experiment at temperature of 54℃ indicated that addition of 10g/l nonionic surfactant so as to obtain saturation absorbance can significantly improved FSC stability. The delamination ratio was 5% only. We infer that a stabile FSC can be obtained only when the surfactant forms an intact layer on the pesticide particles.