Studing On The Influence Factors Of The Formation Process Of Esfenvalerate Microemulsion

Pyrethroid insecticides have make great contribution to human health, crop protection and pesticide sciences because of high effect,low toxicity and Broad Spectrum, expecilly, as the prohibition of five high-toxic pesticides such as methamidophos, there are wider spaces for production, sales volume and New Production exploitation of pyrethroid insecticides. However, In pyrethroid insecticides most of formations are emulsifiable concentrates and the concentration of organic solvent is high. So environment is polluted seriously. Agro-microemulsion is a novel green water-based formation, it is safe to human and environment. But it still has some problems such as bad stability and easy decomposition of effective component. In order to solve this problem, Previous researches have done a lot of work. On the basis of previous researches, we have studied esfenvalerate microemulsion as the following aspects:1. The effect of solvents(acetone,cyclohexanone, toluene and N,N-dimethylformamide)on the screening and stability of esfenvalerate microemulsion was studied by means of diameter mensuration.The result showed that the HLB of the system of solvent-pesticide must be accordance with the surfactant when getting microemulsion with smaller emulsion diameter; the average diameter of emulsion increases with the increasing of solvent. Stable microemulsion can be made with the solvents of cyclohexanone and toluene.But the microemulsion can not be prepared with the solvent of N,N-dimethylformadmide. On the basis, 5% esfenvalerate microemulsion formulation was determined by screening cosurfactant furthermore.2. The effects of counterions on phase behavior and micropolarity of esfenvalerate microemulsion were investigated, the results showed that because of the differences of hydrated radius and counterion binding degree, the anion surfactant with counterions can change the lypohydrophilic character of microemulsion interface, the anion surfactant with K+ can enhance hydrophilic property of microemulsion interface, it was propitious to the formation of O/W microemulsion and hydrolysis stability of esfenvalerate, Na+ and Li+ were not propitious to the formation of O/W microemulsion and hydrolysis stability of esfenvalerate for the biggest hydrated radius.3. The interfacial property of mixed surfactants with counterions was studied by the measurement of interfacial tension, we found that the cmc andγcmc of the system with minor hydrated radius K+ were minor to the system with Na+ and Li+, furthermore, the sequence of oil/water interfacial tension was K+