How Coated Titanium Electrodes are Used in Electrochemical Water Disinfection

How Coated Titanium Electrodes are Used in Electrochemical Water Disinfection

Coated titanium anodes have been used for electrochemical water disinfection of domestic (drinking and swimming pool chlorination) and industrial water. The disinfecting agents like hypochlorite ions and hypochlorous acid can be generated on-site in the electrochemical process, which avoids the storage and transporting of hazardous materials like chlorine gas.

Electrochemical water disinfection is based on the chloride content in the water to generate the disinfecting species. But NaCl has to be added periodically for swimming pool chlorination. NaCl concentration in swimming pool water is usually between 2-5 g/L. For the disinfection process to be effective, water containing high chloride concentrations, such as seawater is recommended. For water containing low chloride concentration (drinking water), it has been found that less than 100 mg/L chloride concentration is sufficient to effectively disinfect the water.

The disinfecting hypochlorite and hypochlorous species are produced at the anode. Cl2 hydrolyzes in water to form the hypochlorous acid. Hypochlorous acid and hypochlorite ions then form a pH dependent equilibrium. In the treatment of low chloride concentration water (drinking water), the current efficiency of the coated titanium anodes for the production of the free chlorine must be as high as possible to compensate for the low chloride water content.

In practical applications, coated titanium anodes are inserted into the water system (e.g. swimming pool chlorination or hypochlorite generation from seawater for the prevention of power plant biofouling of the cooling water system) to be treated. Coated titanium electrodes can be used as both anode and cathode.