丙草胺在有机膨润土上的吸附和释放性能研究

Adsorption of pretilachlor onto organobentonite for controlled release

为减少丙草胺的用量及其对环境的影响,以十二烷基三甲基氯化铵(DTMAC)改性有机膨润土为载体制备丙草胺缓释剂,利用傅立叶红外光谱和X-射线衍射分析了有机膨润土的结构变化,并分析丙草胺在有机膨润土上的等温吸附对其释放动力学的影响。结果表明,DTMAC改性有机膨润土对丙草胺具有良好的吸附能力,并减低其在水中的释放速率。在丙草胺吸附和释放过程中疏水相互作用起关键作用,增加改性剂载量有助于增强膨润土的疏水性及其对丙草胺的吸附能力,从而获得更好的缓释效果。50%的丙草胺从DTMAC用量为可交换阳离子总量的60%、80%、100%和120%的有机膨润土的释放时间T50分别为2.05、2.07、2.97、4.26 d,其与丙草胺在相应有机膨润土上吸附的Freundlich系数Kf存在良好的线性函数关系。

To reduce the usage amount and the impact on the environment, organobentonites modi-fied with different loading levels of dodecyltrimethylammonium chloride （ DTMAC ） were prepared and used as matrix of controlled release formulation of pretilachlor.The structure of organobentonites was characterized by FTIR and XRD, and the sorption towards pretilachlor was investigated.The re-sults were utilized to reveal the effects of organobentonites on the release of pretilachlor.It was shown that organobentonites were of excellent sorption capacity towards pretilachlor and greatly reduced its release in water.The results indicated that hydrophobic interaction played a key roll in the sorption and sustained release of pretilachlor, of which an enhancement could be achieved by increasing the loading level of modifying agent.The time taken for 50% of active ingredient to be released, T50 , from organobentonites with DTMAC loading of 60%, 80%, 100%and 120%of the cation exchange capacity were found to be 2.05, 2.07, 2.97 and 4.26 d, exhibiting excellent linear relationship with the sorption coefficient Kf from Freundlich equation.