Preparation And Performance Characteristics Of Binary Compound Pesticide Microcapsules Based On PPC-PEG

Most of traditional pesticide microcapsules are based on a single active ingredient and non-biodegradable wall materials. It can improve biological activity, delay resistance and reduce environmental pollution by adding reasonable mixed pesticides. The binary pesticide mixtures microcapsules will use biodegradable material as a carrier, which has a better advantage on effectiveness and environmental safety. The studies have shown that thiamethoxam and beta-cypermethrin can show the available good pesticide effect in the proportion of 1:2, but these two kinds of pesticides is not safe enough for some non target organisms. So this paper is mainly aimed to prepare compound pesticide microcapsules by using solvent evaporation method, modified poly (propylene carbonate) as wall material, thiamethoxam and beta-cypermethrin as core materials, and study on its performance.The thiamethoxam and beta-cypermethrin compound pesticide microcapsules are prepared by using solvent evaporation method in which the carrier is consisted of PPC-PEG The optimal preparation conditions of preparing compound pesticide microcapsule is selected by single factor test and orthogonal experiment design. The results show that: when the mass fraction of PVA-1788 is 1%, the core wall ratio of 2:1, V (oil phase):V (Shui Xiang) =20:100, the shear speed is 7000 r/min, emulsification time is 3 min, it can be prepared microcapsules of the average particle diameter in 6-8 ?m, the drug loading and encapsulation efficiency of thiamethoxam was 13.27% and 53.74%, the beta-cypermethrin is 32.60% and 66.02%. Core wall ratio is the main factor of the encapsulation efficiency of the microcapsules.The release properties and release kinetics about thiamethoxam and beta-cypermethrin compound pesticide microcapsules are measured by dialysis bag method.The results show that:the microcapsule has good sustained release performance, it can be divided into the "burst release" and "controlled release", the release concentration ratio of thiamethoxam and beta-cypermethrin is between 1:2.5?1:2 and is closed to the optimum compound ratio of 1:2. The active ingredients can achieve the purpose of efficiency, it shows that the prepared compound microcapsule is suitable. At the same time, the releasing results fitting data fof microcapsules conformed to the Korsmeyer-Peppas data model.Under the acidic conditions, the releasing fitted equation of thiamethoxam in the microcapsules is 1nQ=0.660251nt+1.59486, r2=0.9847; the releasing fitted equation of beta-cypermethrin in the microcapsules is 1nQ=0.685981nt+1.4435, r2=0.9899. Under the neutral conditions, the releasing fitted equation of thiamethoxam in the microcapsules is 1nQ=0.611441nt+1.90081, r2=0.9903; the releasing fitted equation of beta-cypermethrin in the microcapsules is 1nQ=0.678421 1nt+1.61183, r2=0.9876.The acute toxicity of zebrafish is determined by semi static method, the results show that:the half lethal concentration of the thiamethoxam and beta-cypermethrin compound pesticide microcapsule is 2.09 mg/L for 96h, the toxicity regression equations is y=-1.71611+5.36807x,r2=0.994. On the basis of the people's Republic of China Ministry of environmental protection:environmental safety evaluation of chemical pesticide testing standards for the acute toxicity grade compound pesticide microcapsule on zebrafish is "poisoning".