Effects of Several Factors on Operation of an Electro-Advanced Oxidation Process using Fe²⁺/HOCl System

Abstract

The operational conditions for the electro-advanced oxidation process using the Fenton-type reaction of the ferrous ion (Fe²⁺) and hypochlorous acid were discussed in this research. In the process, hypochlorous acid is supplied by the anodic oxidation of the chloride ion (Cl^-) and Fe²⁺ is supplied by the cathodic reduction of the ferric ion (Fe³⁺). 1, 4-Dioxane was used as the hydroxyl radical probe. As the results of the 1, 4-dioxane degradation test, higher current efficiencies of 1, 4-dioxane degradation were observed at pHs of up to 3.0, current densities of up to 2.8 mA·cm^-2, Cl^- concentrations of 10-200 mM, and iron concentrations of 1.0-4.0 mM. In addition, the experimental results showed that the Fe³⁺, the initial iron species was more effective than Fe²⁺, because excessive Fe²⁺ acted as a radical scavenger. A current efficiency of 74.2% was achieved at pH 2.5 as well as a current density of 2.8 mA·cm^-2 at an initial Fe³⁺ concentrations of 1.0 mM and an initial Cl^- concentrations of 100 mM; the current efficiency achieved using Fe²⁺ instead of Fe³⁺ was only 44.9%.