A Study On The Characteristics Of Pre-oxidation Of Aquatic Natural Organic Matters-humic Acid By Potassium Permanganate

Aquatic natural organic matters affect the color, odor in water and are precursors of THMs. They are key controlling pollutants in drinking water. Using advanced instrumental and chemical analysis ,this paper mainly studied oxidation characteristics of potassium permanganate on aquatic natural organic matters (NOM) —humic acid (HA), the effect of pre-oxidation on the treatability of organic matters by subsequent coagulation and filtration,the comparison of the oxidation characteristics of potassium permanganate and ozone.The result show that the effect of coagulation and filtration can be improved by potassium permanganate for pre-oxidation, especially raw water with a high organic matters content. At a low potassium permanganate dose, there is a small amount of potassium permanganate left in water after coagulation, sedimentation. While the dosage of potassium permanganate was increased, residual concentration of potassium permanganate was decreased.HPLC analysis combining with suction time ratio analysis results showed that large organic matters can be broken into smaller ones by potassium permanganate for pre-oxidation. The pyrolysis-GC-MS analysis was applied to identify the main functional groups of the Natural Organic Matters before and after pre-oxidation by potassium permanganate. The results shows that the dominant functional groups detected from the raw water (HA solution) include carboxyl, hydroxyl, ketone, phenol, ether and ester which are linked by benzene and hydrocarbon chains to form the framework of macromolecules. After oxidation by potassium permanganate, many of these cyclic hydrocarbons are no longer in existence and many chain hydrocarbons and aliphatic acids with oxygenated groups are newly formed. Four possible ways of oxidating organic matters were classified. They are dealkylation, side chain oxidation, alcoholization and α-hydrogen atom oxidation.The changing conditions of trihalomethanes were studied by GC-MS. The resultshow that trihalomethanes precursors can be removed effectively by potassium permanganate for oxidation. The mechanism of the reduction of THMFP is that the oxidizing conditions is stronger than chlorine for disinfection. So halogenating reaction can't be occured between oxidizing production.The pre-oxidation of KMnO4 and O3 was contrasted. The effect of ozonation on the alteration of MW of organic matters is larger than potassium permanganate. The more thoroughly Organic matters were oxidated by ozone, the more carboxylic acids in production. THMFP can be removed effectively by potassium permanganate and ozone for oxidation. Their removals were 40.4% and 50.5% respectively.