Effectiveness And Mechanism Of The Oxidative Elimination Of Halogenated Phenolic Compounds By Permanganate In Water

As a typical odor subtance existing in the water, halogenated phenoliccompounds has been a hot research in the field of water treatment. It no only havethe biodegradable and water-soluble strong features, but also to have some toxiceffects of biological. Permanganate used for removal of halogenated phenoliccompounds has more prominent advantages. on the one hand, it can oxidationphenolic hydroxyl unsaturated functional groups of halogenated phenoliccompounds. On the other hand, permanganate does not produce toxic or harmfulby-products in the oxidation process and has obvious advantages comparedhapochlorous and ozone that could produce chlorinated and brominated by-products.Therefore, the reactions kinetics and the influence of environmentalfactors(cationtic or complexing agent) about the permanganate degradation ofhalogenated phenols organic pollutants in this paper. Besides, the mechamism aboutoxidative coupling product also been studied.The halogenated phenolic organic pollutants concentration were determined byhigh performance liquid in condition of false first order kinetics experiment and indifferent pH. In this paper, we select typical iodine phenol, bromophenol andfluorine phenol as the goal of organic pollutants. The research shows thatpermanganate can be applied effevtively to oxidative degradation halogenatedphenol conpounds which contain some unsaturated functional groups. The reactionfollowed a generalized second-order rate law and have a strong pH-dependent. Itwas found that the oxidation of halogenated phenol compounds displayedautocatalisis in the condition of pH=4and5suggesting the catalytic role of in situformed manganese oxides. Besides, the rate values of permanganate andhalogenated phenol conpounds showed an abnormal trend. The phenomenon can beinterpreted as permanganate oxidatation of halogenated phenol conpounds areassociated with the pKaof halogenated phenol conpounds. In the condition of pHless than pKa,the oxidation increased with pH. However, the oxidation decreased with pH when the pH is greated than the pKa.The role of cation and complexing agent on the degradation of phenoloxidation kinitics by permanganate were studied in condition of false first orderkinetics experiment. The presence of common cation ions (Ca2+、Mg2+) have littleimpact on the reaction, so when using permanganate as an oxidant to remove thehalogenated phenol conpounds, we don’t have to consider the effect of comoncations in water. However, ligands can significantly promote the oxidation ofhalogenated phenol conpounds by permanganate.Ligands promote parity statesfollow manganese valence theory that complexing agents can enhance the stabilityof Mn(III) during permanganate oxidation of halogenated phenol organic matter,and then played oxidation ability.With Triple level four rods series linear ion trap mass spectrometer in liquidphase, the oxidation products of permangante were analyzed and determined. Anovel and powerful precursor ion scan (PIS) approach was used for selectivedetection of brominated oxidation products by liquid chromatography/electrosprayionization-triple quadrupole mass spectrometry (LC-MS/MS-PIS). Results showedthat can been measured three main brominated dimeric products.(1) The massnumber for the first product is497/499/501/503（m/z79）.It can be inferred that as akind of polybrominated diphenyl either(2’-OH-BDE-68) is producted by two C-Ofree radicals coupling of each2,4-DBrP.(2) As isomers with the first product, themass number for second product is497/499/501/503(m/z79). It can be supposedthat can be coupling produce through two C-O free radicals coupling of each2,4-DBrP.(3) the third product is also coupling product which is producted throughtwo2,4-DBrP take off a bromine consisting of a hydroxyl group and three bromine.Due to the different rate of oxidative coupling of phenolic oxygen free radicals andthe yield of coupled product, polymerization product was not detected in all.