Titanium anode: the core component of sodium hypochlorite generator
During the electrolysis of sodium chloride solution, the titanium anode increases the yield of sodium hypochlorite to 3.8 mol/(L·h) with a current efficiency of 80%.
Sodium hypochlorite generators, as efficient and environmentally friendly disinfection equipment, play an irreplaceable role in fields such as drinking water treatment, industrial wastewater treatment, and public health security. The performance of their core component, the titanium anode, directly determines the electrolysis efficiency, stability, and service life of the equipment. After specific modification treatment on the surface of the titanium anode, the chlorine evolution overpotential can be effectively reduced, and the occurrence of side reactions can be decreased, thereby improving the production efficiency of sodium hypochlorite.
In the field of industrial wastewater treatment, the application of titanium anodes has achieved effective degradation of high-concentration organic pollutants. Combined with electrocatalytic oxidation technology, it can simultaneously achieve disinfection and pollutant mineralization, promoting the integrated development of environmental protection technologies.
Basic Principles of Titanium Anode in Electrolytic Sodium Hypochlorite Generators
The application of titanium anode in sodium hypochlorite generators involves their unique electrochemical properties and material performance. From the perspective of electrochemical principles, the excellent catalytic activity of titanium anode mainly stems from the special role of the surface active coating. Such coatings effectively promote the conversion efficiency of chloride ions to sodium hypochlorite by significantly reducing the overpotential of the electrolysis reaction.
The change in the content of ruthenium in the coating directly affects the anode activity: when the ruthenium content drops below the critical concentration, the loss of the coating material will lead to the degradation of electrode performance, and this phenomenon has been directly verified by electrochemical measurements and spectroscopy. The integrity of the coating structure and the uniformity of its composition are key factors in maintaining the stability of the electrolysis process. In addition, the bonding strength between the coating and the substrate must also meet the mechanical stress requirements under high current density to ensure that peeling or local failure is avoided during long-term operation.
The material properties of titanium anode further enhance their application potential in electrolytic systems. The titanium substrate itself exhibits excellent corrosion resistance, especially in strong alkaline electrolyte environments where it can form a stable oxide film, effectively resisting corrosion by chloride ions. This characteristic enables titanium anodes to demonstrate significant lifespan advantages in sodium hypochlorite generators.
The performance of titanium anode is also significantly affected by electrolysis process parameters. The regulation of conditions such as electrolyte PH value, temperature, and current density must match the characteristics of the coating material. Excessively high current density may accelerate the loss rate of the coating material, while an appropriate electrolyte flow rate helps maintain the ion balance at the reaction interface. The optimization of parameters in the electrode positioning process (such as electrode spacing and electrolyte flow field design) plays a decisive role in the uniformity of current distribution on the coating surface, which directly affects the service life of the anode and the overall electrolysis efficiency.
The core role of titanium anode in sodium hypochlorite generators is based on their unique electrochemical catalytic mechanisms and material properties. By gaining an in-depth understanding of the interactions between coating compositions, structural designs, and process parameters, theoretical support and practical approaches can be provided for optimizing anode performance, extending service life, and improving system efficiency.
Principle of Sodium Hypochlorite Generator
The working principle of the sodium hypochlorite generator is based on the electrolysis of sodium chloride solution to produce sodium hypochlorite (NaClO) and other by-products. Its core process is that through the electrolytic device, chloride ions (Cl⁻) in the NaCl solution are oxidized to hypochlorite ions (ClO⁻), and at the same time, the oxygen evolution reaction (OER) occurs at the anode.
During the electrolysis process, Na⁺ in the solution migrates to the cathode and combines with OH⁻ to form NaOH, while Cl⁻ is oxidized on the surface of the anode. The reaction formula can be expressed as:
Anode:
2Cl⁻ → Cl₂ + 2e⁻ (main reaction)
Subsequently, Cl₂ reacts with OH⁻ to form NaClO; accompanied by an oxygen evolution reaction:
4OH⁻ → O₂ + 2H₂O + 4e⁻
Titanium anode, as key components of sodium hypochlorite generators, usually adopt a DSA (Dimensionally Stable Anode) structure coated with ruthenium dioxide (RuO₂) and titanium dioxide (TiO₂). This composite coating endows the anode with excellent electrocatalytic activity and chemical stability, effectively reducing the oxygen evolution overpotential, thereby lowering energy consumption. The RuO₂-IrO₂-TiO₂ coating on its surface significantly improves the oxidation efficiency of chloride ions and inhibits the occurrence of side reactions by optimizing the electronic structure.
Titanium anode and sodium hypochlorite generator
The application of titanium anodes in sodium hypochlorite generators is mainly based on their electrocatalytic performance in the chlorine evolution electrolysis process. The generation of sodium hypochlorite relies on the oxidation reaction of chloride ions on the anode surface, which places strict requirements on the electrical conductivity, corrosion resistance, and catalytic activity of electrode materials. Due to their excellent corrosion resistance and mechanical strength, titanium-based materials have become the core electrode materials for such equipment, directly affecting the adsorption, activation, and oxidation reaction pathways of chloride ions.
Design of Titanium Anode in Sodium Hypochlorite Generators
Selection of Titanium Anode Materials
As the core electrode material of sodium hypochlorite generators, the selection of titanium anodes needs to comprehensively consider the electrolytic environment and the stability requirements for long-term operation. The working principle of sodium hypochlorite generators is based on the electrolytic reaction of sodium chloride solution under the action of a direct current electric field. On the anode surface, the chlorine evolution reaction occurs where chloride ions are oxidized to form hypochlorite ions, accompanied by the oxygen evolution side reaction. In an electrolyte environment with strong alkalinity, high chloride ion concentration, and strong oxidizing properties, titanium anode materials must have excellent corrosion resistance, stable electrochemical activity, and good mechanical strength. Titanium-based materials, with their excellent corrosion resistance and moderate electrical conductivity, have become the preferred substrate material for the anodes of sodium hypochlorite generators. Commercially pure titanium exhibits excellent corrosion resistance in neutral and weakly acidic environments.
In terms of titanium substrate selection, commercially pure titanium (such as Gr1 and Gr2) is often used as the base material.
Surface coating technology is a core step in enhancing the electrochemical performance of titanium anodes. Currently, mainstream modification methods include coatings of metal oxides such as iridium and ruthenium. Iridium oxide (IrO₂) coatings can significantly reduce the chlorine evolution overpotential and improve current efficiency. Their conductivity and corrosion resistance have better stability in strongly alkaline environments compared to other transition metal oxides.
The structural design of titanium anode needs to be optimally coordinated with material selection. The geometric shape of the electrode (such as plate, tube, rod, or mesh type) must match the hydrodynamic characteristics of the electrolytic cell to avoid local overheating or accelerated corrosion caused by uneven distribution of the electrolyte. For large-scale industrial installations, the balance between material cost and performance also needs to be considered.
Structural design of titanium anode
The structural design of the titanium anode is a key link in optimizing the performance of the sodium hypochlorite generator. Its geometric shape, dimensional parameters, and surface characteristics directly affect the efficiency of electrochemical reactions and the operational stability of the equipment. In terms of shape design, flat, tubular, and mesh structures are the three most common forms.
- Plate anodes, with their regular rectangular or square planar layout, facilitate uniform current distribution within the reactor. They are particularly suitable for industrial-grade devices requiring high current density, but there is a potential issue of severe local concentration polarization.
- Tubular anodes can effectively alleviate mass transfer limitations, and can significantly improve the utilization rate of chloride ions, especially under low current density operating conditions.
- The mesh anode increases the specific surface area through its three-dimensional structure, which not only reduces the cell voltage but also improves the gas-liquid separation effect.
In the optimization of dimensional parameters, the determination of the effective area of the anode needs to balance the equipment yield and the tank volume. The design of the titanium anode thickness must take both mechanical strength and electronic conduction efficiency into account. The thickness of the titanium anode is mostly 1-3mm; if it is too thin, the mechanical strength will be insufficient, and if it is too thick, it will increase the electronic transmission path and reduce the overall efficiency. The design of the spacing between adjacent anodes is crucial to the distribution of the flow field. The conventional spacing is controlled at 2-5mm to avoid short circuits and ensure uniform electrolyte distribution. For the arrangement of multiple groups of titanium anode arrays, staggered arrangement can better promote electrolyte mixing than parallel arrangement, but attention should be paid to the local overheating problem caused by the edge effect.
Integrated design of titanium anode and generator
The integrated design of titanium anodes and sodium hypochlorite generators needs to comprehensively consider material properties, electrochemical reaction mechanisms, and engineering application requirements. Through structural optimization, flow field distribution regulation, and system integration strategies, an efficient, stable, and long-life sodium hypochlorite preparation system can be achieved.
Integrated design must balance fluid dynamics characteristics and mass transfer efficiency. The flow state of the electrolyte on the anode surface has a significant impact on chloride oxidation, sodium hypochlorite generation, and product transport. The design of the microstructures on the surface of the titanium anode can effectively enhance the turbulence of the electrolyte, reduce concentration polarization, inhibit scaling, ensure uniform flow field distribution, and avoid short-circuit or stagnant flow areas. For operating scenarios with high current density, it is also necessary to consider the thermal management of the anode. Through the design of thermal conductive materials or cooling systems, material degradation or coating peeling caused by excessive local temperatures can be avoided.
System integration also needs to consider the integration of automatic control and monitoring functions. The anode potential, current density, and electrolyte PH value need to be adjusted through real-time feedback from sensors and the PLC system to prevent the chlorine evolution reaction from deviating from optimal conditions. By linking the online pH detection with the acid-base addition system, the electrolyte can be maintained within the appropriate range of 2.5-3.0, inhibiting the side reaction of oxygen evolution. In addition, the titanium anode surface condition monitoring module realizes online evaluation of the scaling degree, providing data support for the maintenance cycle.
System integration also needs to consider the integration of automatic control and monitoring functions. The anode potential, current density, and electrolyte pH value need to be adjusted through real-time feedback from sensors and the PLC system to prevent the chlorine evolution reaction from deviating from optimal conditions. By linking the online pH detection with the acid-base addition system, the electrolyte can be maintained within the appropriate range of 2.5-3.0, inhibiting the side reaction of oxygen evolution. In addition, the titanium anode surface condition monitoring module realizes online evaluation of the scaling degree, providing data support for the maintenance cycle.
For high-salinity or complex water quality conditions, it is also necessary to reserve interfaces for pretreatment units (such as filtration and softening devices) in the integrated design to reduce the negative impact of impurities on the performance of titanium anode.
The integrated design of titanium anode and sodium hypochlorite generators requires multi-disciplinary cross-optimization to achieve a balance between engineering reliability, economy, and operational convenience while ensuring basic electrochemical performance.
Daily maintenance measures for sodium hypochlorite generators
As the core equipment for water treatment and disinfection, the stable operation of a sodium hypochlorite generator directly depends on the performance maintenance of titanium anodes and the optimization of system operating conditions. Based on the technical characteristics of Qixin Titanium electrochemical titanium anode, a professional maintenance plan is formulated from four dimensions: daily inspection, regular maintenance, fault troubleshooting, and safety regulations, aiming to help extend the service life of the equipment and ensure the stability of disinfection effects.
- When the sodium hypochlorite generator undergoes an electrolytic reaction, the effective chlorine content should be kept within 1%. This is because if the chlorine content is too high, it will not only affect the reaction result of the treatment but also affect the service life of the electrode.
- In daily use, because the water in some areas contains relatively high levels of calcium and iron ions, impurities such as CaCO₃ and Fe(OH)₃ will appear during the electrolysis of such water. These impurities in the water may cause short circuits between the anode and cathode or even damage the electrodes. Therefore, users should regularly clean the equipment according to the local water quality conditions to keep the equipment clean and avoid the accumulation of impurities.
- When cleaning the titanium anode used in the sodium hypochlorite generator, it must be handled with care, taking and placing it gently. When cleaning, use a brush to gently sweep away the dirt on the surface. Avoid scraping with sharp tools to prevent damage to the surface coating of the titanium anode.
- During the use of the sodium hypochlorite generator, it is necessary to frequently observe whether the electrolytic current and voltage of the equipment are within the specified range. Timely check the circulation of hydrochloric acid solution and cooling water to prevent blockages.
- After continuous operation for 20 hours, the machine must be shut down for inspection. Close the brine valve of the equipment, empty the chlorine gas in the electrolytic cell, and open the flushing valve for flushing. After flushing, close the flushing valve, empty it, open the brine valve, and make preparations for starting the equipment.
- Sodium hypochlorite generators should be installed indoors in a well-ventilated and well-lit environment, with the surrounding area kept clean and free of clutter. The hydrogen exhaust pipe should be placed outdoors, and open flames or other sources of ignition should be kept away from its vicinity. Smoking and open flames are strictly prohibited indoors.
Core application fields of sodium hypochlorite generators
Qixin Titanium’s titanium anode technology empowers a new ecosystem of disinfection and sterilization
- Sterilization and algae removal in circulating cooling water systems
- Disinfection of production water in the food and beverage industry
- Ultrapure water disinfection
- Electroplating / Surface treatment industry wastewater treatment
- Disinfection of hospital sewage
- Disinfection of Medical Devices and Environment
- Aquaculture water disinfection
- Water disinfection for swimming pools / hot spring pools
The application fields of sodium hypochlorite generators have expanded from traditional municipal disinfection to multiple segmented scenarios such as industrial production, medical and health care, agricultural breeding, and civil and commercial use. Moreover, with the improvement of environmental protection requirements and technological upgrading, their application scope continues to expand. Qixin Titanium, relying on its technical accumulation in the field of electrochemical titanium anodes, has provided reliable guarantees for the core components of sodium hypochlorite generators.
Manufacturer of titanium anode for sodium hypochlorite generator
Qixin Titanium is a manufacturer of titanium anodes from China., focusing on the R&D, manufacturing and application of MMO coated titanium anodes.
Qi Xin Titanium was founded in 2006., with over 20 years of manufacturing experience, we provide stable and reliable titanium anode products suitable for multiple scenarios. We help enterprises improve electrolysis efficiency, reduce operating costs, and offer personalized customization to ensure long-term stable operation.
