Synthesis, Modification And Application In Slow-release Pesticide Of Mesoporous MCM-41

MCM-41 is a new functional material, with easy-to-chemically modified inner and outer surfaces, large specific surface area and pore volume advantages, so it can be used to load various drugs to prepare slow-release pesticide formulations. However, the force between MCM-41 and drug is weak, resulting in low loading content(LC) of drug and short time of its drug effect. This paper through 3-aminopropyl triethoxysilane(APTES) modified MCM-41 to prepare chlorpyrifos/amino functionalized mesoporous silica, and with the help of polyacrylic acid(PAA) by modification effect to prepare pH-responsive PAA/chlorpyrifos/amino functionalized mesoporous silicon system. The salicylaldehyde modified mesoporous silica(SA-MCM-41-5-1) was synthesized by salicylaldehyde Schiff base to organically modified MCM-41. And by virtue of the "bridge" role in the copper ion were prepared chlorpyrifos/mesoporous silica supported copper Schiff base complex(Cu-MCM-41-5-1). Besides, a slow-release pesticide system of SA-MCM-41-5-1-copper ion-chlorpyrifos-SA was built by the modification effect of sodium alginate(SA), in order to improve the LC and slow-release performances of chlorpyrifos. This thesis mainly includes the following aspects:(1) Chlorpyrifos/amino functionalized mesoporous silica system were prepared by impregnation method. The results show that the hydrophobic interaction between amino functionalized mesoporous silica and chlorpyrifos is existed, the Zeta potential is high, the LC and slow-release properties of chlorpyrifos is better. The LC of MCM-41 is 106 mg/g, while the maximum LC of amino functionalized mesoporous silica is 178 mg/g. The addition of APTES was beneficial to improve the slow-release properties of MCM-41 for chlorpyrifos.(2) PAA/chlorpyrifos/amino functionalized mesoporous silica system were prepared by surface modification of PAA. The results indicate that PAA has been modified by electrostatic interaction in the surface of chlorpyrifos/amino functionalized mesoporous silicon. And the slow-release of chlorpyrifos from PAA/chlorpyrifos/amino functionalized mesoporous silica system was mainly due to the blockage effect from the coated PAA. Theas-synthesized system showed significant sensitivity in response to the pH value. When the pH≤7, the release rate of chlorpyrifos decreases with pH increasing. However, in weak base condition, its release rate is slightly larger than the neutral condition. Meanwhile, the drug release rate of the as-synthesized system is also affected by temperature. Their releasing curves could be described by Korsmeyer-Peppas equation.(3) Chlorpyrifos/Cu-MCM-41-5-1 system were prepared by impregnation method. The results show that coordination bond between SA-MCM-41-5-1 and copper ion is exist,besides Cu-MCM-41-5-1 and chlorpyrifos is so as to. The LC of SA-MCM-41-5-1 is 106mg/g, while Cu-MCM-41-5-1 is 295 mg/g. Moreover, the chlorpyrifos/Cu-MCM-41-5-1system also showed significant pH responsiveness. When the pH ≤ 7, the release rate of chlorpyrifos decreases with pH increasing. The release rate of chlorpyrifos in weak base condition is slightly larger than in weak acid condition and its slow-release properties is better in the neutral condition. Their releasing curves could be described by Korsmeyer-Peppas equation.(4) SA/chlorpyrifos/Cu-MCM-41-3-1 system were prepared by chemical complexation.The results indicate that the surface of chlorpyrifos/Cu-MCM-41-3-1 has been coated with SA by chemical complexation to prepare slow-release pesticide system of significant sensitivity in response to the pH value and NaCl concentration. When the pH≤7, the release rate of chlorpyrifos decreases with pH increasing. The slow-release effect in weak acid condition is slightly better than in the weak base condition. And the smaller the concentration of NaCl, the better the slow-release properties of chlorpyrifos. Their releasing curves could be described by Korsmeyer-Peppas equation.