Sodium hypochlorite generator with titanium electrode
Electrode shapes are plate electrodes and tube electrodes.
The cathode material mostly uses stainless steel (1Cr18Ni9Ti), pure titanium or titanium alloy. Since stainless steel is in a state of cathodic polarization, it can be stably corroded during operation, but the electrolyte is highly corrosive. Therefore, after a power failure, the electrolyte should be removed or discharged immediately after cleaning to prevent chemical corrosion. For the H2 reaction, iron-based alloys generally have a moderate overpotential, but have less corrosion resistance than titanium. Titanium and titanium alloys are more resistant to corrosion, but the current efficiency is lower and the cell voltage is higher when making NaClO.
In foreign countries, sodium hypochlorite generators use platinum, iridium alloys and titanium platinized anodes. In China, mainly coated titanium electrodes are currently used. Titanium-plated platinum electrodes are used in sodium hypochlorite baths with higher overpotentials and shorter. The IrO2 coating anode has excellent durability, the overpotential is 0.2V lower than the titanium platinized electrode, and the chlorine evolution current efficiency is higher. The influence of the precipitation of the main component of mg(OH)2 upon coating the anode of the hypochlorite bath. When the anode is exposed to a precipitate, the titanium substrate will undergo bulk corrosion, but if the platinum substrate is plated with a platinum intermediate layer, this phenomenon can be prevented.
The content of heavy metal ions chromium and lead in the sodium hypochlorite melt produced by the sodium hypochlorite generator used for sanitization shall meet the requirements of the water quality standard and hygienic requirements of Chapter 2 of GB 5749. Therefore, the sodium hypochlorite generator used for sanitization shall not use graphite electrodes. And lead dioxide plating electrode.
Sodium hypochlorite generators are divided into two categories, namely sanitation and environmental protection, depending on the use. Sanitary disinfection refers to the use of sodium hypochlorite generators that are directly related to human health such as disinfection of drinking water, disinfection of sanitary appliances and tableware, and sterilization of vegetables, fruits, and foods. Environmental protection refers to sodium hypochlorite generators that are not directly related to human health, such as industrial wastewater treatment, hospital sewage treatment, and all other industrial sectors using sodium hypochlorite solutions.