Study On The Transformation Of Halide Ions And The Formation Of Byproducts In The Advanced Oxidation System Of Persulfate?PDS? Activated By Fe²⁺

At present,there are various halogen ions(Cl-,Br-,I-)in drinking water,which may produce emerging tri-halogenated disinfection by-products(iodineorganic by-products,bromate(BrO3-),Chlorinated by-products),these have strong biological toxicity and genotoxicity.The active material produced by the advanced oxidation technology of ferrous iron(Fe2+)/persulfate(PDS)is high-valent iron(Fe(?)).Its strong oxidizability has attracted the attention of many researchers in recent years.Focus on researching the system and commit to its practical application in water treatment.Compared with the strong oxidizing property of persulfate,the oxidizing ability of persulfate alone is weak,and it must be activated in a specific way(transition metal)to produce active substances.In the current water treatment process,we plan to use ferrous ions to activate persulfate to study its effect on the conversion of chlorine,bromine,and iodide ions and the formation of by-products.In consideration of practical application,the system will lead to halogenated disinfection by-products such as iodine organic by-products,bromate and chlorite which are harmful to health.This topic mainly studies the conversion rules and methods of single bromide ion,single chloride ion,bromine iodide ion synchronization,chlorobromide ion synchronization and chlorobromide ion synchronization in ferrous/persulfate system,and also investigates the concentration of oxidant persulfate,Ferrous ion concentration,pH and other single factors.The conversion rate of halogen ions in the ferrous/persulfate advanced oxidation system under different single factors was studied.By studying the two factors of oxidant persulfate concentration and ferrous ion concentration,the optimal concentration ratio of the system was Fe2+:PDS=4:5;when the pH range increases from 3 to 7,the conversion rate of halogen ions gradually decreases as the pH value increases.At pH=3,the conversion rate of halogen ions is optimal,and the conversion rate of bromide ions alone is 48%;the conversion rate of chloride ion alone is 31%;the conversion rate of iodine ion when iodine and bromine are synchronized is 46%and the conversion rate of bromine ion is 23%;The conversion rate of ions is 31%;the conversion rate of chloride ions when chlorine,bromine and iodine are synchronized is 7%,the conversion rate of bromine ions is 17%,and the conversion rate of iodide ions is 43%.At the same time,using tetramethylene sulfoxide(TMSO)as an experimental probe to study and analyze the experimental mechanism,it is concluded that the active material of the experimental system is high-valent iron(Fe(?));when multiple halogen ions are converted at the same time,the concentration is dominant Alternatively,the more reductive halogen ions react preferentially,and at the same time,the conversion path of the halogen ions is analyzedBy adding humic acid(HA)to the ferrous/persulfate advanced oxidation system,the total organic carbon in the water body is increased to simulate the actual water body,It was found that when the concentration of humic acid changed from 0 to 10 mg/L The generation rate of halogenated organic by-products showed a tendency to increase first and then remain unchanged.When the concentration of humic acid was 6mg/L,the amount of halogenated organic by-products reached the highest.