Ultrasound-induced Phosphotungstic Acid Catalyzes The Degradation Of Sulfamethoxazole By Hydrogen Peroxide And Potassium Iodide

The general residues of sulfonamide antibiotics in the water environment pose a potential threat to human health and the ecological environment,so it is of great significance to carry out research on its removal methods.This article takes the sulfonamide antibiotic sulfamethoxazole(SMX)as the research object,based on the oxidation of iodine radicals and hydroxyl radicals,the oxidative effect and mechanism of sulfamethoxazole catalyzed by H2O2/KI catalyzed by phosphotungstic acid(H3PW12O40,PW12).The main content of the paper includes:(1)Ultrasound can significantly enhance the removal effect of H2O2/KI on SMX(60min,the degradation rate increased from 26.88%to 94.6%),the degradation process conforms to the proposed first-order reaction kinetics.Ultrasonic power,initial pH value,H2O2 and KI concentration have certain effects on the degradation effect.The power is in the range of 65-195 W,and the degradation rate of SMX increases with the increase of power;when the pH is in the range of 3.2-6.1,the removal rate gradually decreases;the optimal concentration of H2O2 and KI was 120.0 mmol/L and 2.4 mmol/L,respectively.Free radical inhibition experiments show that iodine free radicals(I2·-and I·)are the main active substances for the degradation of SMX in the US/H2O2/KI system.(2)Compared with US/H2O2/KI,US/PW12/KI also effectively improves the degradation rate of sulfamethoxazole.Ultrasonic excitation of PW12 generates excited state PW12*,which can directly oxidize SMX or further react with water to generate HO·,HO-oxidizes KI to produce I· and I2-.The UV spectrum shows that A460nm(I2)and A350nm(I3-)increase.The main active substances for US/PW,2/KI degradation of SMX are I2·-,I· and HO·.(3)Combining ultrasound,PW12 and H202/KI,the degradation rate of sulfamethoxazole continued to increase,and the SO42-concentration increased during the degradation process.Three products were mainly detected by HPLC/MS.The degradation route was the oxidation of NH2 on the benzene ring to NO2;Addition reaction of HO·.