High-voltage Needle-plate Pulsed Spark Discharge Combined With Ag-BiVO₄ To Treat Tetracycline Hydrochloride

In recent years,with the sustained and rapid development of my country's economy,the issue of environmental pollution has gradually become a hot issue for people to focus on.Among the many environmental pollution problems in our country,the most prominent one is water pollution.Tetracycline production wastewater has the characteristics of complex composition,high COD concentration,difficult to biodegrade,and strong pollution.Therefore,the research on the treatment technology of tetracycline production wastewater has very important practical significance.The traditional methods of processing tetracycline hydrochloride include physical adsorption and biodegradation,etc.which have defects and urgently need to develop new technologies.The combination of high-voltage pulsed discharge plasma and catalyst technology can improve the removal effect of pollutants,accelerate the reaction rate,and will not cause secondary pollution to the environment.This paper studies the treatment of tetracycline hydrochloride(TCH)antibiotic wastewater by high-voltage pulsed discharge(HVPD)in conjunction with a catalyst(Ag/BiVO₄).In this study,a separate HVPD system was first established,and the effects of pulse frequency,pulse voltage,electrode spacing,air flow,solution initial concentration and solution conductivity on TCH removal were investigated,and the single-factor optimal experimental parameters for pulse discharge were determined.The following conclusions are drawn:when the pulse frequency and pulse voltage gradually increase,the removal rate of TCH also increases;when the electrode spacing and air flow gradually increase,the removal rate of TCH presents a trend of first increasing and then decreasing.The initial concentration of the solution is 100mg·L^-1,the conductivity of the solution is 200?s·cm^-1,the pulse frequency is 60 Hz,the pulse voltage is 24 k V,the electrode spacing is 7mm,and the air flow rate is 2.5L·min^-1Under the conditions,the discharge time is 60min,the removal rate of TCH is87.9%,and the mineralization rate is 47.3%.In this study,the Ag/BiVO₄ catalyst was further prepared.Through XRD and SEM characterization of different catalysts,the catalyst with the best Ag loading was determined.At the same time,the influence of pH value and dosage on the TCH removal rate and the stability experiment of the catalyst were considered.The HVPD-Ag/BiVO₄synergistic system was established.The experimental results showed that when the dosage of 1%Ag/BiVO₄was 0.1g,the TCH removal rate was99.8%and the mineralization rate was 67.8%when discharged for 60 minutes under the optimal reaction conditions.Both strong acidic conditions and strong alkaline conditions are not conducive to the removal rate of tetracycline hydrochloride.This study explored the mechanism of HVPD to remove TCH molecules.By analyzing and comparing the effects of hydroxyl radicals,hydrogen peroxide and ozone on the removal of TCH during the discharge process,the active substances with the greatest degrading effect on TCH were obtained.At the same time,the changes of TOC and pH were measured,and a series of experiments showed that the mineralization rate of pulsed discharge and Ag/BiVO₄catalyst on tetracycline hydrochloride wastewater was higher than that of pulsed discharge alone.During the discharge process,the pH of the solution gradually decreases,and the solution eventually becomes acidic;·OH plays a key role in the degradation of TCH molecules;H₂O₂cannot directly act on TCH molecules,but acts indirectly through conversion to·OH;O₃directly under acidic conditions Oxidizes TCH molecules,and decomposes under neutral conditions to produce·OH to act on TCH molecules.In this study,the synergy of high-voltage pulsed spark discharge technology and catalysts provides a new research idea for the treatment of tetracycline hydrochloride.