Application of continuous non-diaphragm electrolytic cell in electrolysis of sodium chloride to produce sodium hypochlorite
Electrochemical electrolyzers have been used in chlor-alkali industry, metallurgy, organic electrosynthesis, chemical industry and other fields. It is a device that converts electrical energy into chemical energy. In this device, current passes through the electrolyte solution to cause redox reactions in the cathode and anode regions. . Generally, it includes materials such as anode, cathode, diaphragm, and tank. In recent years, with the development of non-diaphragm electrolytic cell technology and application fields, this non-diaphragm electrolysis technology has also played an important role in many fields. Here, we exchange views on the application of continuous diaphragmless electrolyzers in electrolysis of sodium chloride to produce sodium hypochlorite.
There have been many studies on the electrolytic chlorination of Cl-, and the sodium hypochlorite electrolytic cell is an on-site generation device. Its design structure, selection of electrode materials, operating parameters and other requirements play an important role in the on-site preparation of sodium hypochlorite.
1. About the concentration of sodium chloride solution: when the temperature is controlled at about 25 degrees Celsius, constant current electrolysis, and the cathode current density is controlled at 2000a/m2, electrolysis is performed on different concentrations of sodium chloride. As the concentration of sodium chloride increases, The tank pressure decreases accordingly, the effective chlorine concentration increases after electrolysis for a period of time, and the salt consumption is higher.
2. Regarding the current density: under the condition of the effective chlorine output of 1000g/h, according to the above test environment, the current density is adjusted between 400-5000a/m2, as the current density increases, the cell pressure increases; As the current density decreases, the effective chlorine output also decreases. It is found that the current electroplating is controlled at about 2000a/m2, and the effective chlorine content of sodium chloride solution gradually slows down with the increase of electrolysis time.
3. Regarding temperature: when the current density is controlled at about 2000a/m2, the NaCl concentration is about 3%, and the temperature is adjusted, the bath liquid will decrease with the decrease of temperature. However, the increase in temperature also has an accelerated effect on the side reactions in the liquid phase. It is ideal to control the temperature at 25-30 degrees Celsius.
4. Regarding the selection and structural design of electrolytic cell and electrode plate materials: the compact and reasonable electrolytic cell design can fully electrolyze the solution, reduce the influence of stray current, and improve the electrolysis efficiency. The use of ruthenium-based noble metal mixed oxide coating with better electrocatalytic activity can improve the service life of the electrode plate. In short, the design of the electrolytic cell and the use of the electrode plate material also maintain a stable effective chlorine output and output. important part.
Under the same operating conditions, the use of a non-diaphragm electrolytic cell reduces the number of connecting components, improves the current efficiency compared to the diaphragm electrolytic cell, and reduces energy consumption and cost. Therefore, diaphragmless electrolysis is more economical and easier to operate and maintain. In the process of use, attention should be paid to the influence of current density, electrolyte concentration, temperature, pH and other factors. Select the electrolyzer suitable for the structure and operating conditions.