Study On Degradation Of 2,4,6-trichlorophenol By Zero-valent Iron/Potassium Persulfate System Enhanced With Ultrasonic And Its Mechanism

As one of organic compounds,Chlorophenol was used widely,which caused more and more environmental and health problems in recent years.In this paper,we chose 2,4,6-trichlorophenol(2,4,6-TCP)as the target contaminant,to study the degradation of 2,4,6-TCP with ultrasonic oxidation of zero-valent iron activated potassium sulfate in the simulated wastewater.The main influencing factors and the mechanism of the degradation of 2,4,6-TCP was also investigated.The effects of 2,4,6-TCP initial concentration,initial pH value of solution,amount of potassium persulfate and zero dosage of iron on the degradation of target pollutants were investigated.The results showed that when the initial concentration was 20mg/L,the zero value iron dosage was 0.2g/L,the initial pH value of the solution was 6,the amount of potassium persulfate was 0.4g/L,the reaction time was 2,4,6-TCP removal rate of up to 95.5%.The reaction experiment of different systems and the reaction kinetic process in the first 20 min were analyzed.The first 20 min reaction was in accordance with the first order reaction kinetics equation.The reaction rate constant was 161.44%,and the synergetic effect was significant,mainly through the increase of potassium persulfate Activation rate to improve the target pollutant removal rate.Fe0/US/PS system has a good effect in removing 2,4,6-TCP under acidic and alkaline conditions,and the removal rate is more remarkable under alkaline condition.The effects of zero valence iron dosage and initial pH on the pH value,iron ion concentration and potassium persulfate concentration of the reaction process were studied.With the progress of the reaction,the pH value was basically decreased,and the solution had a large amount of acid material generation.Under the optimum zero-valence iron dosage and pH value,the concentration of ferric ions can be maintained relatively stable,and the optimal efficiency of activated potassium persulfate is reached.Potassium persulfate concentration decreases gradually with the progress of the reaction,and the removal rate of 2,4,6-TCP is changed by affecting the activation rate of potassium persulfate with different zero valence iron dosing and pH.Free radical inhibitors showed that sulfate free radicals and hydroxyl radicals were present in the system,in which sulfate radicals played a major role.The results of TOC measurement show that the mineralization rate of the system is much lower than that of the simultaneous 2,4,6-TCP,and the mineralization process is slow.The chloride ion concentration gradually increased by ion chromatography,indicating that 2,4,6-TCP dechlorination occurred under strong oxidizing of sulfate radicals.2,4,6-TCP degradation is the first dechlorination into dichlorophenol and monochlorophenol,and then converted into benzene ring intermediate products,benzene ring is oxidized into esters,and further decomposition into alkanes and small molecules Acid,and finally mineralized into carbon dioxide and water.