苯酚在Ti／PbO2电极上的电氧化反应

Electrooxidation reaction of phenol at Ti/PbO_2 electrode

利用线性伏安法和恒电流电解法研究了苯酚在Ti/PbO2电极上的电催化氧化反应,通过电氧化过程中反应物和中间物的高效液相色谱测定,研究了苯酚在Ti/PbO2电极上电催化氧化的反应机理.实验发现,Ti/PbO2电极对水溶液中苯酚的电氧化具有显著的催化作用,25℃时,对初始浓度为2 mmol/L的苯酚水溶液,恒定电流密度为50 mA/cm2,电解3 h,苯酚转化率为98.02%,有机碳去除率为54.36%.苯酚在Ti/PbO2电极上电催化氧化要经过对苯二酚或邻苯二酚、对苯醌、反丁烯二酸和草酸,最终变成二氧化碳和水的历程.第一步反应苯酚转化的主产物是对苯二酚.对苯二酚转化为苯醌和苯醌转化为反丁烯二酸的反应为慢反应,反丁烯二酸转化为草酸的反应为快反应.

The eleetrocatalytic oxidation of phenol at Ti/PbO2 electrode was studied by linear sweeping voltammetry and galvanostatic electrolysis. The electrocatalytie oxidation mechanism of phenol at Ti/PbO2 electrode was explored by HPLC analysis of phenol and its oxidation intermediates in the electrolytic processes. It was found from the experiments that Ti/PbO2 electrode can effectively eleetroeatalyze the oxidation of phenol in the aqueous solution. The conversion of phenol and the removal ratio of oganie carbon compounds have reached 98.02% and 54.36% in electrolytic time 3.0 h respectively, while electrolyzing with constant current 50 mA/cm^2 in the solution eontainig initial concentration 2 mmol/L of phenol at 25 ℃. The posible pathway of the electreoxidation of phenol is phenol→p-hydroquinone or o-hydroquinone→p-benzoquinone→ fumaric acid→oxalic acid, and the final products are CO2 and H2O. The main product of the oxidation of phenol is p-hydroquinone. The electrooxidation of p-hydroquinone to pbenzoquinone and p-benzoquinone to fumaric acid are slow reactions,and fumaric acid to oxalic acid is a fast reaction.