Study On The Technology And Mechanism Of Ultrasonic Electroc Hemical Degradation Of Chlorpyrifos

In this topic,chlorpyrifos pesticide wastewater is selected as the object of degradation.The removal of chlorpyrifos pesticide wastewater under different factors was investigated.At the same time,an optimization experiment was designed through response surface analysis（RSM）,and the degradation rate of chlorpyrifos was used as the response value.By comparing the experimental value and the predicted value,the best experimental conditions can be obtained comprehensively.It is:ruthenium,iridium and titanium as electrode material,temperature of 25℃,reaction time of 1h,pH=7,voltage of 25 V,ultrasonic power of 240 W,electrolyte anhydrous sodium sulfate concentration of 3 g/L,degradation rate of98.8126%.The degradation effects of ultrasonic,electrochemical and ultrasonic electrochemical technologies on chlorpyrifos were explored,and the activation energy of the three systems were studied respectively.The results showed that using ultrasonic electrochemical technology can greatly improve the degradation effect of chlorpyrifos under the same conditions.Moreover,the introduction of ultrasound can reduce the activation energy of the reaction using electrochemical technology alone.Ultrasonic electrochemistry has a higher synergistic effect,and the degradation process follows first-order reaction kinetics.This article uses the theory of liquid mass（LC-MS）and quantum mechanics to preliminarily infer the degradation products and pathways,and predicts the degradation reactions and degradation products of organic matter through quantum chemistry methods.It has a more accurate predictive ability.According to the quantum chemical DFT method B3LYP/6-31G（d）basis set calculation and prediction,using the Gauss 06program to make HOMO and LUMO judgments to predict the initial reaction site of chlorpyrifos.At the same time,combined with the detection methods such as LC-MS,the degradation mechanism of ultrasonic electrochemical degradation of chlorpyrifos wastewater is speculated:desulfurization-oxidation,phosphate bond hydrolysis and dechlorination mechanism.After desulfurization and oxidation,the C1-Cl10 on the pyridine ring is broken,and the reaction sites Cl8 and Cl9,which are easily attacked by free radicals,are replaced by hydroxyl groups.After the chlorpyrifos is first hydrolyzed,the C1-Cl10 on the pyridine ring is broken,and then the P=S bond is oxidized to P=O,and then H₂O and OH^-attack the electrophilic groups in the chlorpyrifos molecule and hydrolyze.At the same time,this paper uses Matlab to simulate and compare different parameters（sound pressure amplitude,ultrasonic frequency,initial bubble radius,liquid surface tension,liquid viscosity）on the motion state of cavitation bubbles,so as to judge the effect of ultrasound introduction.The sound pressure amplitude,ultrasonic frequency,and initial radius greatly affect the cavitation effect.HO·is a major free radical oxidant that is detected in large quantities in bubbles.This highly reactive substance has been clearly identified in an ultrasonic aqueous solution by electron spin resonance.Oxidation groups produced during the collapse of HO·cavitation bubbles are also the main active free radicals for ultrasonic degradation of organic matter.Ultrasound not only enhances the mass transfer process,but also depolarizes and cleans the electrode.