| Due to the large cultivated land area and various kinds of crops planted in China.Therefore,the quantity and variety of pesticide products used are various,and China has become the largest producer and exporter of pesticide raw materials in the world.However,due to the neglect of the management of enterprise wastewater discharge by some pesticide enterprises,pesticide-containing wastewater is discharged into an open environment,resulting in increasing pressure on the ecological environment.Diazinon is a broad-spectrum and highly effective organophosphorus pesticide.It can be used to effectually control apple silverfish,grubs and needlebug.However,the wide use of diazinon has also brought some environmental problems,such as water eutrophication,soil hardening and destruction of ecosystem.Therefore,an urgent need to develop a targeted wastewater treatment technology to treat wastewater runoff and industrial emissions to meet environmental requirements.Hydrodynamic cavitation as a new advanced oxidation technology,has many incomparable advantages over existing technologies,such as simple equipment structure,friendly environment and low energy consumption.Moreover,hydrodynamic cavitation technology is still in its infancy and has not been widely used in sewage treatment.In this paper,we used a self-made hydrodynamic cavitation device,took the simulated organophosphorus pesticide diazinon wastewater as the treatment object,the influencing factors of hydrodynamic cavitation generator and operating conditions on the degradation of diazinon were studied.The Ultraviolet-visible spectrum（UV-vis）of diazinon degradation by HC was analyzed,and the degradation degree of organic carbon（TOC）of diazinon was calculated.Furthermore,the possible degradation pathway of diazinon was analyzed by Liquid Chromatograph-Mass Spectrometer（LC-MS）,and the possible degradation mechanism of diazinon by HC was put forward.The main research results of this paper are as follows:（1）When the temperature of diazinon solution=40°C,the solution p H=7.0,the initial concentration of diazinon=10 mg/L,the inlet pressure=5.0 bar,and the solution volume=5.0 L,the three holes orifice plate with shrinkage angle of 45°has the best HC degradation ratio,after 150 min treatment,the value is 43.80%;（2）Using optimized orifice plate（the three holes orifice plate with shrinkage angle of 45°）,the solution temperature=30℃,the solution p H=4.0,the initial concentration of diazinon=10 mg/L,inlet pressure=5.0 bar,the volume of the diazinon solution=5.0 L.The degradation ratio of the diazinon solution by HC can reach 50.52%after150 min treatment;（3）And on this basis,add three kinds of inorganic oxidants（Na Cl O4,KIO4 and K2S2O8）with different proportions and types to the degradation system,comparative kinetic by using different oxidizing agent on hydrodynamic cavitation degradation of organophosphorus pesticide diazinon synergistic efficiency.It was found that,when the added K2S2O8 to diazinon is 5:1（molar mass）,the system has the best degradation ratio at 150 min（92.48%）.And through calculations,The addition of K2S2O8 does have a synergistic effect with HC,and the cost of treating diazinon is￥0.020/L;（4）UV-vis and TOC show that the method of hydrodynamic cavitation could effectively degradation of organophosphorus pesticide diazinon.Three degradation pathways of diazinon were identified by LC-MS. |
