| Many adjuvants in pesticide formulation were used to improve the stability and efficiency of the formulation. Among which, solvent and emulsifier are at an important field position in the pesticide formulation. Because of high content and toxicity of these two adjuvants, the hazards to human being, environment and food safety must be concerned. In recent years, as the people's safety concerns for food and environment and the rising price of crude oil, the negative effect of organic solvents and emulsifiers in pesticides preparation has been attached great importance, to develop an easily degradable, reproducible and non-petroleum solvent and emulsifier as alternatives became a new topic. OSA-modified starch and biodiesel as two new green energies with renewable and environmental compatibility had potential use in pesticide preparations.In this paper, as example with 2.5% Lambda-cyhalothrin EW and used OSA-modified starch and biodiesel as substitute emulsifier and solvent, high stable emulsions of the Lambda-cyhalothrin was prepared. The effects of different process parameters and environmental factors on the stability of emulsion were studied, and the stability mechanism of Lambda-Cyhalothrin O/W Emulsion preparated with OSA-modified starch as emulsifier was primarily discussed. The influence of OSA-modified starch and biodiesel on physical properties of preparation dilutions and toxicity of lambda-cyhalothrin was determined. Further more, the effect of methyl oleate content on the physical characteristics of spray liquid and the bioactivity of lambda-cyhalothrin emulsion in water was investigated. The following aspects were studied in this thesis:1. OSA-modified starch had excellent emulsification ability to biodiesel, high stable emulsions could be prepared with OSA-modified starch, and the mean droplet diameters of emulsion were about 1.2~2.7μm. Biodiesel had good dissolving ability to Lambda-cyhalothrin, and compared with organic solvent, it had high flash point, so in safe to production, storage, transportation, it had weak volatility also.2. High stable 2.5%~16% Lambda-cyhalothrin EW could be prepared with OSA-modified starch and biodiesel. The emulsions with mean oil droplet diameter increased by only 0.1~0.8μm after storing at 25℃for 6 months or at (54±2)℃for 14 days, and approximately 100% of the oil remained stabilized in the emulsion, wich had better stability than the conventional emulsions.3. Higher stable emulsions could be prepared by the path of emulsification at high viscosity with concentration of pretreating fluid of OSA-modified starch in the range of 15%~25%. Smaller oil droplet diameters were obtained when the rotational speed was increased, which had no significant effect on homogeneity of emulsions. On the other hand, an increase of the shearing time reduced the span of oil droplet diameter distribution, but had no significant impact on mean oil droplet diameter.4. The stability mechanism of Lambda-Cyhalothrin O/W Emulsion preparated with OSA-modified starch as emulsifier was studied by means of measuring the effects of the OSA-modified starch content, inorganic ions, pH value and temperature on the Zeta potential of oil droplets and surface loads(Γ) of OSA-modified starch.When the OSA-modified starch content was 7%, Zeta potential could reach the maximum, and the surface loads(Γ) appear to reach saturation level; Na+, Mg2+and Al3+ were able to decrease Zeta potential by compressing the electronic double layer thickness of oil droplet surface, which could lead to molecular flexibility enhanced due to electrostatic exclusion weaken and make the surface loads(Γ) smaller. If the inorganic ions were the same, the capacity of compressing the electronic double layer thickness of oil droplet surface by Na+, Mg2+ and Al3+ successively enhance, and the the degrees of Zeta potential reduction and surface loads(Γ) increase were successively obvious. As the pH affected the ionization of OSA-modified starch in water, in the range of alkaline, strong electrostatic repulsive force was provided by more carboxylic ion being ionized, then the Zeta potential increased but surface loads(Γ) decreased. As temperature increased, the solubility or escaping tendency of OSA-modified starch increased, so the Zeta potential and surface loads(Γ) decreased, furthermore the difference was not obvious at low temperatures, but the higher the temperature was, the less the Zeta potential and surface load(Γ) was.The OSA-modified starch that is adsorbed at the oil droplets surface was able to stabilize the emulsion by very strong electrostatic exclusion and steric-hindrance double effect.5. The surface tension of Lambda-cyhalothrin EW prepared by biodiesel were decreased compared with the dimethylbenzene formulation, but The surface tension of OSA-modified starch formulation were slightly improved, and the maximum retention ability (Rm) on wild cabbage leaves were obviously enhanced, the dried duration were markedly prolonged, and the virulence of 2.5% Lambda-cyhalothrin EW with OSA-modified starch and biodiesel to the Spodoptera exigua Hübner, Agrotis ypsilon, which had no differences.6. The effect of methyl oleate content on the physical characteristics of spray liquid and the bioactivity of lambda-cyhalothrin emulsion in water was studied. Results demonstrated that with the methyl oleate content increased(5%,15%,25%,35%) in the lambda-cyhalothrin emulsion in water, the maximum retention ability (Rm) on three crop leaves increased by 21%~125%, surface tensions decreased by 6~12mN/m, dry duration increased by 6~20min. When the methyl oleate content enhanced from 5% to 35%, the toxicity of lambda-cyhalothrin to P.rapae and A.ypsilon enhanced significantly which presented as the mortality increased (maximum 50%), meanwhile, the control efficacy of 7 days increased from 79.22% to 96.54%, when applied with 3000 times diluents.
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