Study On Electrochemical Dechlorination Of Aromatic Componds By In Situ FTIR Spectroscopy

Electrochemical dechlorination of chloro-aromatic componds has been studied widely for its social benefit and economic returns,so the research on the reaction mechanism is important for its theoretic guide to the industrial application.Thus electrochemical dechlorination of chloro-aromatic componds such as 4-chlorophenol、2-chlorophenol、2,4-dichlorophenol、3,4,5,6-tetrachloropiclinic aicd has been investigated using cyclic voltammetry and in situ FTIR techniques.Results of cyclic voltammograms showed that Ag electrode exhibited a good performance for the electroreduction of chloro-aromatic componds. The possible electroreduction mechanism of a series of chloro-aromatic componds on Ag electrode by in situ FTIR spectroscopy suggested that the chloro-reactant has been electroreduced to its radical ion initially,then the unstable chloro-radical ion was dechlorinated to the aromatic radical,after that the aromatic radical on the surface of the electrode was added an electron to formate aromatic anion,or the aromatic radical in solution was acted with the aromatic radical ion containing chlorine to generate the chloro-reactant and the aromatic anion,at last the aromatic anion was protanized to its aromatic hydrocarbon.And the dechlorination pathway of multichlorine aromatic componds to aromatic hydrocarbon was seem to the above chloro-reactant.Results of cyclic voltammograms showed that Pt electrode responded well for the electrooxidation of the aromatic componds in alkaline solution whereas was easy to lose its electrochemical activity gradually.The possible electrooxidation mechanism of chlorophenols on Pt electrode by in situ FTIR spectroscopy suggested that chlorophenols was dechlorinated to phenol firstly,then phenol was added an hydroxyl group to be dihydroxybenzene,or chlorophenols was added an hydroxy to yield OH-adducts containing chlorine firstly,then it was dechlorinated to dihydroxybenzene;With the increase of potential,the dihydroxybenzene could be electrooxidized to benzoquinone;Afterwards the dihydroxybenzene and benzoquinone was trasformed to maleic acids、fumaric acid、acryl acid、ethane diacid;Finally some Dight weight carboxylate such as formate and acetic acid and ultimate product CO₂ and water were achieved.