毒死蜱/环糊精在锌铝类水滑石中插层的制备和性能

Preparation and Characterization of Chlorpyrifos/Cyclodextrin Complex Intercalation into ZnAl-Layered Double Hydroxide

以层状锌铝类水滑石(ZAL)为主体,分别以磺丁基醚-β-环糊精(SBECD)和羧甲基-β-环糊精(CMCD)包结毒死蜱(CPF)为客体分子,分别在乙醇和N-甲基吡咯烷酮(NMP)溶剂条件下制备ZAL-SBECD-CPF和ZALCMCD-CPF插层材料,采用X射线粉末衍射(XRD)、傅里叶变换红外(FT-IR)光谱和热重-差热分析(TG-DTA)对其结构和热稳定性进行表征。结果表明,CPF/SBECD和CPF/CMCD均可成功在ZAL中插层,且在NMP溶剂条件下合成样品的衍射峰强度要强;插层CPF分子有较高热稳定性。此外,还对ZAL-SBECD-CPF和ZAL-CMCD-CPF在pH=5.0,6.8的环境条件下的释放行为进行研究和对比。结果发现,ZAL-SBECD-CPF样品几乎没有缓释性能,而ZAL-CMCD-CPF有一定的缓释性能,这与客体分子在层间排布方式不同有关。两种样品在pH=6.8条件下的释放百分率均高于pH=5.0,这与释放环境和环糊精(CD)分子结构密切相关。ZAL-CMCD-CPF的释放行为可很好的用二级动力学方程和parabolic diffusion模型来描述,说明药物客体分子释放主要受扩散过程控制。研究结果将有助于开发ZAL-CMCD-CPF在农药制剂方面的应用价值。

Chlorpyrifos（CPF） was firstly included in sulfonated hydroxyethyl-β-cyclodextrin（SBECD） and carboxymethyl- β- cyclodextrin（CMCD） in an ethanol or 1- methyl- 2- pyrrolidinone（NMP） solvent. Inclusion complexes（CPF/SBECD and CPF/CMCD） were then intercalated into the galleries of Zn Al-layered double hydroxides（ZAL） to synthesize ZAL-SBECD-CPF and ZAL-CMCD-CPF intercalated materials. The structure and thermal stability of nanohybrids were characterized by powder X-ray diffraction（XRD）, Fourier transform infrared（FT-IR） spectroscopy, and thermal gravimetric and differential thermal analysis（TG-DTA）. The results showed that both CPF/SBECD and CPF/SBECD were successfully intercalated in the interlayer. The samples prepared in the NMP solvent had a stronger diffraction peak intensity than those prepared with ethanol. The intercalated CPF molecules had a high thermal stability. Furthermore, the release behaviors of CPF from ZALSBECD-CPF and ZAL-CMCD-CPF nanohybrids were investigated and analyzed at pH 5.0 and 6.8. ZAL-SBECD-CPF had almost no slow-release behavior, while ZAL-CMCD-CPF showed distinct slow-release, which was caused by the different arrangements of cyclodextrin（CD） in the interlayer. BC release from nanohybrids was faster and the amount released higher at pH 6.8 than at pH 5.0. This was closely correlated with the structural type of CD and the release media. The CPF release kinetic process can be fitted well by pseudo-second-order and parabolic diffusion models. ZAL-CMCD-CPF remarkably exhibited controlled release behavior, suggesting that it can be potentially applied as a controlled release pesticide formulation.