What is Electrochemical Oxidation for Defouling?

What is Electrochemical Oxidation for Defouling?

Electrochemical oxidation defouling includes the production of chemicals (oxidants) at the electrode surface, such as hydrogen peroxide at the cathode, which is an effective biocide and reactive oxygen species at the anode (O2, O2-, O3, OH radicals). Defouling of inorganic scaling can be achieved when the potential is applied without pressure to increase cross flow velocity and shear removal efficiency of scaling. The majority of electrochemical defouling methods using intermediates (chemical oxidants) focus on anodic oxidation or cathodic production of oxidants.

Electrochemical advanced oxidation processes, EAOP, typically focus on oxidation of the complex organics and inorganics addressed in advanced oxidation processes at low concentration using electrodes and chemical oxidants as intermediates. Electrochemical oxidation of wastewater, EAOP, is usually done by cross flow through electrode banks. It has been explored for porous membranes including Ebonex Ti4O7 anodes and ceramic dimensionally stable anodes (DSA), for example for oily wastewater. Electrochemical advanced oxidation processes are able to oxidize a wider range and concentration of persistent micropollutants, nitrogen species, and microorganisms than traditional advanced oxidation processes. The reactive oxygen species, ozone, hydrogen peroxide, and hydroxyl radicals, are ideal for wastewater treatment with electrodes as they do not produce dissolved solids unlike chlorination of organics and intermediate hydroxyl radicals that non-selectively oxidize most organics. The rate limiting step at a steady state in most cross flow EAOP is the diffusion of the hydroxyl radicals and organics.

Reaction density increases with flow-through porous anodes. Their defouling ability is limited to the avoidance of a fouling layer by continuously oxidizing the low concentration organics as they pass through the electrochemically reactive membrane. If we apply EAOP to removing adsorbed organic filtration cakes by hydroxyl radicals, the rate limiting step is likely to be the production of hydroxyl radicals at the surface of the electrode and base of the fouling layer, which is a function of water availability at the surface and can be enhanced by back flushing with water.