2,4-二氯苯酚的电化学氧化降解反应研究

采用循环伏安法和原位红外光谱技术研究了2，4-二氯苯酚在Pt电极上的电化学氧化降解反应，结合Fukui函数值预测了2，4-二氯苯酚在电化学氧化过程中的反应位点. 结果表明，Pt电极对2，4-二氯苯酚有良好的电催化活性，2，4-二氯苯酚在电极表面反应主要有3个途径：直接通过电化学反应脱去氯离子，生成苯酚；在·OH的进攻下，C—Cl键断裂，4位Cl较2位Cl先脱去，生成苯二酚，并可进一步氧化生成苯醌以及不饱和羧酸；在·OH的进攻下发生苯环开环反应，生成含氯不饱和羧酸. 在1700 mV左右，2，4-二氯苯酚可经电化学氧化生成CO₂.

Studies on Electrochemical Oxidation Reaction of 2,4-Dichlorophenol on Pt Electrode

Cyclic voltammetry(CV) and in situ FTIR spectrometry were employed to study the electrochemical oxidation mechanism of 2,4-dichlorophenol(2,4-DCP) in NaOH solution. Density functional theory(DFT) was used to calculate the Fukui function for 2,4-DCP and gave the information on possible reactive sites of 2,4-DCP during electrochemical oxidation. CV results show that the Pt electrode exhibits a high electrochemical activity for the electrochemical oxidation reaction of 2,4-DCP. On the basis of in situ FTIR data, the electrochemical oxidation reaction of 2,4-DCP is as follows: (1) C—Cl band of 2,4-DCP is broken to form phenol directly; (2) C—Cl band of 2,4-DCP is broken and C—O band is formed with ·OH radicals, and the Fukui function results show that chlorine atom at 4 position is easier to be replaced with the hydrogen or ·OH radicals. Then hydroxylation reaction happens on the C4-position of phenol leading to form hydroquinone which is subsequently electrochemically oxidized to benzoquinone. With the potential increasing, aliphatic carboxylic acids are formed after the ring cleavage; (3) part of 2,4-DCP is electrochemically oxidized to chloromaleic acid directly. At about 1700 mV, CO₂ could be formed during electrochemical oxidation reaction of 2,4-DCP on Pt electrode.