The Studies Of The Preparation And The Controlled-release Properties Of Three Kinds Of Chlorpyrifos-loaded Systems

Controlled-release formulation forpesticides has many advantages suchas long efficacy of duration, high utilization, low toxicity, environmental-friendly, andso on. It will have a broad application prospects in pesticide formulations processing.Chlorpyrifos is a widely-used insecticide with many outstanding capabilities in China.However, the main formulation of chlorpyrifos is emulsifiable concentrate(EC),which consumed a lot of harmful organic solvent, and resulted in environmentpollution. Controlled-release formulation of chlorpyrifos can increase the insecticideefficency and decrease the potential environmental impact. This study is to investigatethe preparation conditions of20%chlorpyrifos capsule suspensions, chlorpyrifos soliddispersions and chlorpyrifos-β-CD complexs. The mechansim of the controlledrelease of the three formulations above also were studied. The primary results were asfollows:1. Determination the types and dosages of core solvents and emulsifier. Xylenewas chosen as core solvent by comparing the solubility of candidate solventsto chlorpyrifos, the shape of the prepared microcapsules, the dosage of thesolvent was6g xylene to dissolve20.6g chlorpyrifos. HAU-11was selectedas the suitable emulsifier by coparing the shape and the mean diameter of theprepared microcapsules and the optimizing dosage of was2%.2. The effects of the dosage of urea-formaldehyde resin, emulsifying time,emulsifying speed, acid adding time on mean diameter, distribution andencapsulation efficiency of the microcapsules were studied by single factortest combined with orthogonal test. The dosage of urea-formaldehyde resinin the preparation was15%, emulsifying time was25min, emulsifyingstir-speed was1500r/min, acid adding time was60min. In theaforementioned conditions, the effects of solidify time and solidifytemperature on encapsulation efficiency of microcapsules were studied, thesolidify temperature of the microcapsules with high encapsulation efficiencywas controlled at55℃for2.5h. 3. The qualified dispersants and wetting-dispersing agents for the chlorpyrifoscapsule suspensions were chosen by comparing the mean diameter,dispersity and suspension rate of the prepared formulations, the optimizingformula was that HAU-51as dispersant, HAU-61as wetting-dispersingagents. The dosage of HAU-51was1.5%. The dosage of HAU-61was3%.4. The thickening agent was determined by checking the stability, pourabilityand dispersity of the preparations. The result indicated that the optimizingformula of thickening agent consist of xanthan gum and magnesiumaluminum silicate, both dosages of them were0.1%.5. The ethylene glycol was selected as suitable antifreezing agent by checkingthe appearance, flowability, suspension rate of the preparations after freezingstorage test, and5%was the optimizing dosage.6. The effect of the rate of charge, preparation temperature, preparation time,stirring speed on solid dispersions embedding rate were tested by singlefactor test. Combining orthogonal test we determined the best preparationconditions: the rate of charge was1:20, preparation time was40mins,preparation temperature was60℃, the stirring speed was400r/min. Theembedding rate of chlorpyrifos solid dispersions we prepared was95.88%.7. The effects of the rate of charge, inclusion temperature, time on theembedding rate of solid dispersions were discussed through single factor test.The effects of combining orthogonal test ultimately determine the bestpreparation conditions: the rate of charge was1:3, preparation time was2h,preparation temperature was50℃, the inclusion rate was41.51%.8. The release performances of the three kinds of controlled-releaseformulations were determined. The results showed that the chlorpyrifos...