基于正硅酸乙酯的农药缓释微胶囊制备优化及表征

Synthesis Optimization and Characterization of Pesticide Sustained Release Microcapsule Based on TEOS

摘要:

采用溶胶-凝胶法，以正硅酸乙酯（TEOS）为硅前驱体，制备二氧化硅凝胶对天然除虫菊酯进行封装，并以载药率为评价指标，使用响应曲面法设计BBD（Box-Behnken实验）实验确定最佳的制备工艺条件为：pH=9.02，TEOS投加量为0.96 g，反应温度36.5 ℃，微胶囊载药率最大值可达到38.0 %，平均粒径约为13.5 μm。结果表明，微胶囊封装后的原药在250 ℃以下稳定性有着显著提升，4 ℃避光储存4个月，载药率仅下降6.2 %。微胶囊缓释性良好，在100~200℃条件下能有效减少原药的质量损失。微胶囊对于淡色库蚊和白纹伊蚊幼虫均保留较高的杀虫活性，对蚜虫和黏虫的毒性甚至略高于原药。

Abstract:

Natural pyrethrins are encapsulated with silicon dioxide gel prepared via the sol-gel method using tetraethyl orthosilicate as precursor. Taking drug loading rate as the evaluation index， the response surface methodology is used to design the BBD （Box-Behnken design） experiment to determine the optimal preparation conditions as follows： pH is 9.02， the dosage of TEOS（tetraethyl orthosilicate） is 0.96 g， and the reaction temperature is 36.5 ℃. The drug loading efficiency and average particle size of the microcapsules are 38.0 % and 13.5 μm， respectively. The results show that the stability of encapsulated drug is significantly improved below 250 ℃. The drug loading efficiency decreases by only 6.2% after it is stored in the dark at 4 ℃ for four months. The microcapsules demonstrate a good sustained-release property， and can effectively reduce the quality loss of the drug at 100~200 °C. The microcapsules also exhibit a high insecticidal activity against Culex pipiens pallens and Aedes albopictus larvae， and are even slightly more effective against aphids and stick insects than the original drug， endowing them with a great application value.