| China is a large agricultural country.The production and development of agriculture is the basis for the rapid development of the social economy and the continuous improvement of the people's lives.The production of safe,high quality and reassuring agricultural products is the goal we have been pursuing.However,the flow pattern of development model,the low demand for production and the unsound supervision system lead to the serious excess of the residue of agricultural products in China.In order to solve a large number of crops from pest threats in the process of planting,agricultural products processing enterprises have to spend the high cost of raw materials to reduce pesticide residues,in order to meet the consumer demand,the use of Chinese herbal medicine is closely linked with us.Profound history of Chinese herbal medicine has spreaded,the aging population is becoming more and more serious.Now western medicine,palliative to allow more people to choose and rely on Chinese herbal medicine,Chinese herbal medicine has become an indispensable element of China's pharmaceutical industry,people's daily life and human health development.Today,the development of traditional Chinese medicine is in full swing,the resulting problems have increased with each passing day,pesticide residues in Chinese medicinal materials are the most prominent in these questions.According to the relevant reports,The mortality rate of global annual pesticide poisoning was 9.95%in the last more than 10 years,even more than 89.5%of the cancer prevalence rates,and more than 100 diseases are closely related to the excess residues of pesticides.At present,the kinds of pesticides on the market are countless,amino acid methyl ester,organophosphorus,pyrethroid,tri-azole play pivotal roles in the reproduction of plant diseases and insect pests,It can not only inhibit the invasion of diseases and pests,but also have the effect of removing mite and weeding.when diseases and insect pests encroach crops,and reduce the degree of damage to the crops to a minimum.However,pesticides also have some harm,their undecomposable and insoluble chemical properties,they will be preserved along with the growth of Chinese medicinal plants and keep accumulating.Many pesticide residues in different parts of the medicinal materials have different degrees of residue.Furthermore,the residue of pesticides has also caused great pollution to the environment.Based on the facts above,it is very necessary to degrade pesticides using high voltage pulsed electric field.High voltage pulsed electric field technology is a highly efficient,economical and pollution-free method for the degradation of pesticides.This paper studies the different parameters effect of pulsed electric field on tri-azole pesticides(myclobutanil,propiconazole and tebuconazole),and the optimal parameters of the pulse electric field for the degradation rate of pesticides are summarized.For more articulusly expression of the degradation mechanism,static fields were loaded on myclobutanil,propiconazole and tebuconazole molecules by Materials Studio,and analyze the changes of structure and the internal energy of the molecules.According to the relationship between the intensity and the energy of the electric field,the degradation principle of 3 kinds of pesticides is derived from the pulsed electric field:When the chemical structure changes,the energy changes required when chemical bonds break,and the corresponding optimized parameters of pulsed electric field(pulse intensity,loading time,pulse counting),and a random model between the energy of a molecule and the force of an electric field is established and proved by experiments.This practice provides a theoretical basis for the degradation of tri-azolics from a microscopic point of view.The main contents are as follows:1.In this paper,3 optimal parameters of high voltage pulse degradation of myclobutanil,tebuconazole and propiconazole pesticide was studied through experiments(electric field intensity,pulse width and counting of pulses).The optimum conditions of the degradation of myclobutanil,tebuconazole,propiconazole were pulse intensity 2800V,length 90,number 170;strength 3000V,length 80,number 120;strength 3000V,length 95,number 200,respectively.It is concluded that the degradation conditions are suitable for both independent residues and compound residues for three kinds of pesticide.2.Using the GC-MS test verified through high voltage pulses after myclobutanil,propiconazole and tebuconazole,and the corresponding degradation were obtained.The quantitative analysis of the chromatograms and mass spectrograms of the 3 kinds of pesticides is made by SIM scanning.The effect of pesticide degradation is judged by the peak area value,and the degradation rate has a significant change.It provides a powerful theoretical guarantee for our future selection of suitable high voltage pulsed electric field intensity,pulse width and number of pulses3.The relationship between the energy loss and the electric field force is clarified by the kinetic mechanism of the pulsed electric field on the liquid medium(tri-azolol).That is to say that the loss is the work done by the electric field force.The energy increment is equal to the difference between the input energy value and the loss value.The increment acts on the liquid medium and affects its molecular structure.4.The basic structure model of pesticide molecule was constructed by Masterials Studio software.The correlation between the intensity of the electric field of the pulsed electric field and the internal energy of the chemical bond and the displacement between the molecules is demonstrated through experiments and data analysis.The effect of electrostatic field on 3 kinds of three azole pesticides was analyzed by DMol3.With the increase of external electric field intensity,the energy between the three azoled pesticides is also increasing,the attraction between molecules is changing,and the activity of ion(Cl-)is also increasing,they are beneficial to molecular transition.It is deduced that the fracture of the chemical bond needs to absorb energy,which provides a powerful theoretical basis for our research. |
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