The electrochemical generation of ferric ions in cooling water as an alternative for ferric chloride dosing to effect flocculation

The research deals with the electrochemical dissolution of iron in cooling water as an alternative to ferric chloride dosing to effect flocculation. The generation of this anion-free flocculant has far-reaching implications in a cooling-water system. Its primary benefit is the elimination of chloride dosing into the system, chloride being an initiator of pitting corrosion, the most destructive and insidious form of corrosion. Alternating current was applied to the electrochemical reactor in order to curb the deleterious passivation of the electrodes, characteristic of direct current application. Through the manipulation of process variables several process phenomena were identified. Untreated cooling water proved to be an ideal electrolyte for the generation of the desired quantify of ferric ions. It was observed that dissolution in an alternating field is accompanied by the generation of heat in the electrolyte, which aids the precipitation of carbonate compounds in the clarifiers. It was also established that while the solution pH has very little effect on the process, the voltage applied to the electrodes and the flow rate of the cooling water through the reactor are significant in determining the extent of the dissolution process.