毒死蜱/脲醛树脂微胶囊的制备工艺优化及缓释动力学

Sustained-release Kinetics and Preparation Process Optimization of Chlorpyrifos/Urea-formaldehyde Resin Microcapsules

随着人们健康与环保意识的不断加强,农药施用量大、效率低、高残留等问题日益受到人们的重视,对农药进行微胶囊化,有助于有效解决当前农药使用过程中所面临的问题。采用脲醛树脂作为壁材,以十二烷基硫酸钠为乳化剂,采用原位聚合法制备毒死蜱/脲醛树脂微胶囊。研究了乳化剂种类和用量、pH值、酸化时间对微胶囊粒径及其分布的影响,并进一步探讨微胶囊的载药量、包封率及释放动力学。结果表明,采用3%(质量分数)的十二烷基硫酸钠为乳化剂,在酸化时间为90min、酸化终点pH值为2.5、搅拌速度为1 200r/min、芯壁比为1∶3、固化温度为60℃时,所制备的毒死蜱/脲醛树脂微胶囊的粒径分布窄,平均粒径约为113μm,载药量达53%以上,包封率达62%以上。毒死蜱/脲醛树脂微胶囊的缓释性能及动力学研究结果显示,所制备的毒死蜱/脲醛树脂微胶囊的缓释效果明显,10天内能释放90%的药物,释放过程遵循Fick扩散机理。可见,制备的毒死蜱/脲醛树脂微胶囊具有较高的载药量、较好的包封率以及缓释性能,可进一步开发为新型的农药制剂,并为开发缓释农药新剂型提供理论支持与实践参考。

With people’s increasing awareness of environmental protection and health,low efficiency,large dosage and residual problems caused by widespread use of pesticides were concerned extensively.Pesticide microcapsules has shown lots of benefits to help improve the utilization rate of pesticide and achieve other aims as well.Using urea-formaldehyde resin as wall material and chlorpyrifos(CPS)as core,the chlorpyrifos/urea formaldehyde resin microcapsules(CPS/UFMCs)was fabricated by in-situ polymerization.The effects of emulsifier sorts and dosage,pH,acidification time on particle size and distribution of chlorpyrifos/urea-formaldehyde microcapsules(CPS/UFMCs)were studied,and the optimal process of CPS/UFMCs preparation was obtained.Moreover,the release performance and kinetics of the CPS/UFMCs prepared by optimal process was carried out to further investigate the loading capacity of microcapsules,encapsulation efficiency and release kinetics.The results showed that CPS/UFMCs had a narrow particle size distribution and a small average size with 3wt%sodium dodecyl sulfate(SDS)as emulsifier,the acidification time of 90 min,pH of 2.5,core/wall ratio of 1∶3 and curing temperature of 60℃.In addition,the average size of CPS/UFMCs prepared with the optimization process was around 113μm.Meanwhile,the CPS/UFMCs showed excellent loading performance with more than 62%CPS encapsulated and the CPS loading rate was more than 53%.Moreover,the investigation of release performance showed the chlorpyrifos was released sustainably from the CPS/UFMCs,and more than 90%of the CPS encapsulated was released within 10 days.Subsequently,the release kinetics was analyzed following mathematical models of Korsmeyer-Peppas equation and Higuchi equation.In the kinetic study,the results showed that the release process of CPS/UFMCs followed a Fick diffusion mechanism.Generally,the prepared CPS/UFMCs shows high drug loading,efficient encapsulation and excellent release performance,and can be further developed as a new type of pesticide formulation,which can provide theoretical support and practical reference for the development of new formulations of sustained-release pesticide.