Comparison of Electrode Materials for Degrading Organic Pollutants

Comparison of Electrode Materials for Degrading Organic Pollutants

Strong oxidant species like hydroxyl radicals, atomic oxygen, hydrogen peroxide, perhydroxyl radicals, and free chlorine are produced in the electrochemical reactions. These powerful oxidizing agents are capable of degrading organic pollutants and kill the bacteria. By electrolysis of water, anodic catalysis to produce adsorbed hydroxyl radicals.

 The electrode material strongly affects the production of reactive species such as Cl2, OCl- , H2O2, ozone, ·OH, and ·HO2, affecting consequently the disinfection efficiency of the process.

The ideal electrode material would be one totally stable that allows the generation of oxidants efficiently at a low overpotential. The region of potential in which the selected reaction occurs is important since its relationship to the electroxidation of the wastewater will determine the overall current efficiency of the process. The evolution of oxygen (at the anode) and hydrogen (at the cathode) are competing reactions and simultaneously produce protons (O2evolution) and hydroxyl ions (H2 evolution). These reactions may be inhibited by the particular electrode material and/or by additives to the electrolyte.   


Regardless of the selected material, unfortunately, electrochemical reactions normally occur in a rather unselective manner and most of the energy from the power source is spent on side reactions and heat generation. The rate of an electrochemical reaction can be either activation-controlled or mass transport-controlled. Therefore, it is evident that to enhance the rate of these reactions it is important to (1) provide electrodes with high surface area, and (2) promote turbulent conditions in the electrolyte through agitation, movement of the electrode itself, or turbulence promoters in the cell.