Electrooxidation, Electrocoagulation, and Electro Fenton Method for Wastewater Treatment

Electrooxidation, Electrocoagulation, and Electro Fenton Method for Wastewater Treatment

Electrooxidation (EO), electrocoagulation(EG) and electro-Fentonare(EF) are widely used electrochemical technologies. They are known as high efficiency, effective, eco-friendly, and cost-effective processes for the treatment of organic pollutants and it yields a very effective reduction result. What are the differences between these different electrochemical processes?
 
Electrooxidation
In the electrooxidation process, pollutants can be removed by direct electrolysis or indirect electrolysis. In direct electrolysis, pollutants exchange electrons directly with the anode surface without the involvement of other substances.
In indirect electrolysis, organic pollutants do not exchange electrons directly with the anode surface but rather through the mediation of some electroactive species regenerated there which act as intermediaries for the electrons shuttling between the electrode and the organic compounds. Indirect electrolysis can be a reversible or an irreversible process, and the redox
reagent can be electrogenerated by either anodic or cathodic processes. Process selection depends on the nature and structure of the electrode material, experimental conditions, and electrolyte composition.
 
Electrocoagulation
Electrocoagulation involves in situ generations of coagulants by electrolytic oxidation of an appropriate sacrificial anode (iron and aluminum) upon application of a direct current. The metal ions that are generated hydrolyze in the electrocoagulator mainly at pH values in the range of 6.0–7 to produce various metal hydroxide complexes and neutral M(OH)3. These products are necessary for the removal of soluble or colloidal pollutants by virtue of various mechanisms including ionic complexation or ion exchange on the floc surface active sites, and the enmeshment of the colloidal pollutants into the sweep flocs. During or at the end of the process, flocs are removed either by sedimentation or by flocculation by means of hydrogen gas released from the cathode.

Electro-Fenton
Electro-Fenton methods broadly include electrochemical reactions that are used to generate in situ one or both of the reagents for the Fenton reaction. The reagent generated depends on cell potential, solution conditions, and the nature of the electrodes. The EF process is generally characterized as having four different types; H2O2 is externally applied while a sacrificial iron anode is used as a ferrous ion source.