What Electrodes Material is Used for Electrochemical Treatment?

What Electrodes Material is Used for Electrochemical Treatment?

The selection of electrode materials for electrochemical treatment must take into account issues such as cost, accessibility, stability at the required potentials, selectivity, composition, and pH of the reaction medium, nature of intermediates substances and products, and environmental compatibility. Care has to be taken in the proper selection since most electrodes are useful in only a limited range of potential and pH.

With conventional metal electrodes, electrochemical treatments are unsuitable because of the low stability of the anodes and the poor current efficiency. Regarding stability at the required potentials, the selected electrode material must be such that it will not corrode under the application of the needed potentials. It must be noted that the majority of organic and inorganic substances require high potentials for their oxidation, often higher than that for the oxidation of water. Consequently, oxidized noble metal surfaces (for example Pt, Ir, Ru) are usually necessary for the oxidation of organic substances, although their cost poses a major restriction for their widespread use. Some cheaper substitutes such as oxidized nickel and lead can be used in aqueous media.

Electrode materials for the electro-disinfection process vary widely. Cathode materials include stainless steel, copper, graphite, carbon cloth, and reticulated vitreous carbon; anode materials include platinized titanium or niobium, tantalum, graphite, carbon, metal oxides, silver, copper, nickel, Monel, dimensionally stable anodes, and combinations thereof. Electrocatalytic materials can be incorporated into electrodes, for example, in the form of coatings, such as ruthenium oxide (RuO2), mixed iridium oxide (MIO), and/or titanium oxide (TiO2).

Three-dimensional electrodes have also been successfully used because they offer high surface areas per unit volume. Additionally, the passage of the solution through these electrodes produces local turbulence, which is beneficial for mass-transfer processes. Commercially available high surface area anodes include graphite, reticulated vitreous carbon, titanium, stainless steel, nickel, and Ebonex (a Ti-based ceramic).