Dissertation
Dissertation > Agricultural Sciences > Plant Protection > Pesticide ( chemical control ) > Plant chemical protection theory > Pesticide residues

Study on Removal Efficiency of Organic Phosphorus Pesticides Residues by Ultrasonic and Air Bubble Cleaning

Author ZhangRui
Tutor DingWeiMin
School Nanjing Agricultural College
Course Agricultural Biological Environmental and Energy Engineering
Keywords Ultrasonic wave Pesticide Residues Vegetables Air bubble Organic phosphorus pesticide
CLC S481.8
Type Master's thesis
Year 2010
Downloads 13
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With the the pursuit of a healthy lifestyle, eating more vegetables has become a trend. There are many reasons for the phenomenon of pesticide residues in leafy vegetables. First, misuse of pesticides; second, the growth cycle of leafy vegetables is short; third, it is not easy to cleaning leafy vegetables. In order to reduce pesticide residues in leafy vegetables, we should find new types of pesticide with environmental protection; On the other hand, finding new ways to safely remove pesticide residues is greatly important in reality.In this paper we researched the method of determination residues of dimethoate, triazophos and chlorpyrifos and study the degradation trend of the three kinds of organic phosphorus pesticide. Based on ultrasonic cavitation and "hot pot", theoretical analysis has been made on using ultrasonic methods remove pesticide residues in vegetables, and the effects of the related parameters of ultrasonic cavitation and "hot pot" on pesticide residues in vegetables have also been discussed in this article.We adopt acetonitrile as extraction solvents in preparation. The extraction solution has little impurity. The step of preparation was simplified, and has the better rate of recovery rate. It can achieve the request of the residues of organic pesticides determination. Through the test of degradation trend of three kinds of organic pesticide, we obtain the degradation equation of 1.5 times concentration uses one time in lettuce.We get the degradation equation of dimethoate, triazophos and chlorpyrifos; the residues half life of dimethoate is 2.43d; the residues half life of triazophos is 2d; the residues half life of chlorpyrifos is 2.06d;Using the vegetable washing machine as a tool, spreading pesticide in the fields, picking up vegetables after 48 hours, and dealing with them with different cleaning methods, we find ultrasonic cleaning and air bubble cleaning is better than other cleaning methods. To study the factors affecting ultrasonic cleaning effect, we measured the removal of the three kinds of organic phosphorus pesticide in different ultrasonic power, bubbles, cleaning time. Results showed that:power of ultrasonic, bubble and cleaning time have a significant impact on the rate of removing effects of the three kinds of organic phosphorus pesticides. With the increasing of ultrasonic power from OW to 125W, the removal efficiency of the three kinds of organic phosphorus pesticide has nearly linear upward trend; but during 125W to 1000W, the rate of dimethoate, triazophos and chlorpyrifos has a smoother change trend. The rate of dimethoate, triazophos and chlorpyrifos removing effects increased with the prolonging of time of treatment, but the change is not great after 10 minutes. Bubble help increase the rate of removing effects of the three kinds of organic phosphorus pesticide. When the ultrasonic power is 1000W, the air bubble is 25m2/h and the time of treatment is 15 minutes, removing rate of dimethoate, triazophos and chlorpyrifos in vegetable is 87.11%,70% and 84.14%.

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