Source analysis of benzene degradability in floating cathode electro-Fenton system based on COD removal ratio

The H 2 O 2 , O 2 − , OH, and HO 2 generated by the anode and cathode are considered the possible sources of the oxidizing power of the electro-Fenton system. For improving the current efficiency, the assessment of the degradability of anode and various active substances to pollutants is an important prerequisite. The COD removal ratio was used as a judgment index for the first time, and the effect of various active substances produced by the electro-Fenton anode and cathode on the removal of COD in benzene-containing wastewater was analyzed. The results revealed that the contribution rate of the active substances produced by the cathode for the COD removal is 63.21%. Among the active substances, the contribution rate of OH, which is the most important active substance, is 58.86%. The contribution rate of the anode is 36.79%. The COD removal ratio of the system is considered the best when I   =  200 mA, pH = 3, and [FeSO 4 ] 0  = 60 mg/L, which is estimated as 72.59%. The contribution rate of OH, which is produced by the cathode, to the removal of COD is positively correlated with the total COD removal ratio. These findings are of great significance. That is only by improving the utilization rate of OH and reducing the ineffective consumption of OH, the removal of COD can be promoted, and the bottleneck problem of low electro-Fenton current efficiency can be solved.