Titanium Anodes for Sodium Hypochlorite

Sodium hypochlorite (NaOCl) is a chemical widely used in water treatment, disinfection, bleaching and other fields. In the production process of sodium hypochlorite, titanium anodes, as an important part of the electrolysis equipment, play a key role. Titanium anodes not only have excellent corrosion resistance and electrical conductivity, but also can effectively improve the yield and production efficiency of sodium hypochlorite.

Requirements for Titanium Anodes Used in Sodium Hypochlorite Production

Titanium anodes play a crucial role in the production of sodium hypochlorite. The choice of anode material will directly affect the electrolysis efficiency, the amount of chlorine and sodium hypochlorite produced, and the service life of the anode. The following are some of the main requirements that titanium anodes need to meet in this process:

Corrosion Resistance

The production process of sodium hypochlorite involves a large amount of chlorine gas (Cl₂) and high – concentration chlorides (Cl⁻), which are highly corrosive. Therefore, the anode material must have extremely strong corrosion resistance to prevent the anode from being corroded or damaged. Titanium, as a base material, has excellent corrosion resistance and can work stably in chloride solutions for a long time.

Good Electrical Conductivity

The electrical conductivity of the anode material has a direct impact on the electrolysis efficiency. Titanium has high electrical conductivity, which can reduce the loss of electrical energy and improve the efficiency of the electrolysis reaction.

High Catalytic Activity

The surface of the titanium anode is usually coated with a layer of precious metals (such as iridium, ruthenium, etc.) or other oxide coatings to improve its ability to catalyze the evolution of chlorine gas. This can reduce the voltage required during the electrolysis process, thereby improving the electrolysis efficiency and reducing energy consumption.

High – Temperature Resistance

Heat is generated during the electrolysis process. Therefore, the titanium anode needs to have good high – temperature resistance to prevent the material from deforming or degrading in a high – temperature environment.

Long Service Life

The production of sodium hypochlorite is a continuous process. The anode material needs to have a long service life to avoid frequent replacement or maintenance, thereby reducing production costs.

Types and Coatings

Titanium anodes themselves have good basic properties. However, in order to further improve their performance in the chlorine gas electrolysis reaction, surface coating technology is usually used. Common coating materials for titanium anodes are:

1. Iridium – Coated Titanium Anodes (Ir/Ti)

• Characteristics: Iridium is a precious metal with extremely high corrosion resistance and good electro – catalytic performance, and it performs well in the chlorine evolution reaction.
• Application: Iridium – titanium anodes are widely used in the production of sodium hypochlorite, which can improve the efficiency of chlorine gas generation and reduce the electrolysis voltage.

2. Ruthenium – Coated Titanium Anodes (Ru/Ti)

• Characteristics: Ruthenium also has good electro – catalytic performance and is cheaper than iridium. Ruthenium – coated titanium anodes can provide high stability during the electrolysis process, especially when used in high – concentration chloride solutions, they have good corrosion resistance.
• Application: Ruthenium – titanium anodes are commonly used in large – scale production of sodium hypochlorite and are a more economical anode material.

3. Titanium Alloy – Coated Anodes (such as Platinum – Titanium, Iridium – Titanium – Molybdenum Alloys)

• Characteristics: Titanium alloy – coated anodes are usually composed of a titanium base material plus alloy coatings of iridium, platinum, molybdenum, etc., which can provide good electro – catalytic activity, corrosion resistance and high stability.
• Application: In the electrolysis of sodium chloride with high requirements for anode durability, titanium alloy – coated anodes can greatly improve production efficiency and anode life.

4. Oxide – Coated Anodes

• Characteristics: Some non – precious metal oxides (such as cobalt oxides, iron oxides, etc.) can also be used to coat titanium anodes. Such coatings not only have good catalytic properties, but also can provide a long service life at a relatively low cost.
• Application: Although these coatings are cheaper than precious metal coatings, their corrosion resistance and catalytic activity may be poorer. They are usually used in low – current density or small – scale production.

Sodium Hypochlorite

1. Application Fields: Sodium hypochlorite generators, nuclear cooling water anti – fouling treatment, ballast water treatment, domestic sewage treatment
2. Product Specifications: Component form or processed according to drawings. Divided into tubular electrodes or plate – type electrodes
3. Anode Life: 500 – 1500A/m², greater than 2 years
4. Electrochemical Performance and Life Test (Reference Standards HG/T2471 – 2007, Q/CLTN – 2012)
   

   Name	Enhancement mg	Polarization Rate mv	Chlorine Evolution Potential V	Test Conditions
   Titanium – based Ruthenium – Iridium	≤10	40	<1.13	1mol/L H2SO4

5. Actual Operating Parameters (Marine Environment)
   

   Working Conditions g/L	Current Density A/m²	Salt Consumption kg	Power Consumption kwh/kg	Sodium Hypochlorite Yield g/L
   30 – 50	500 – 1500	4 – 7	3.7 – 7	6 – 10

6. Reaction Expressions are as follows:

   NaCl + H2O → NaClO + H2 ↑

   Anode: 2Cl⁻ – 2e → Cl2

   Cathode: 2H⁺ + 2e → H2

   Solution Reaction: 2NaOH + Cl2 → NaCl + NaClO + H2

7. Product Background and Introduction

   The principle of electrode – made sodium hypochlorite is to use diaphragm – free electrolysis, and generate sodium hypochlorite through homogeneous secondary chemical reactions. The reaction principle of the anode is to electrolyze sodium chloride (in tablet form) put into the swimming pool. During the electrolysis process, sodium hypochlorite is formed. The most suitable salt concentration is 3% – 5%. The electrodes used in sodium hypochlorite generators include plate – type electrodes and tubular electrodes.

   The anode material can be a coated titanium electrode. The mixed oxide – coated titanium anode has a long service life, and the over – potential of this coated titanium anode is relatively low, the chlorine evolution current efficiency is high, and the energy – saving effect is good.

   Sodium hypochlorite generators are divided into two categories according to their usage: for sanitation and disinfection and for environmental protection. Our company currently produces titanium anodes for sodium hypochlorite generators used in aspects related to human health such as swimming pool water disinfection, tableware disinfection, and sanitary food disinfection. In terms of environmental protection, there are mainly sodium hypochlorite generators for hospital sewage treatment and various industrial wastewater treatment. The requirements for the specification, shape and coating performance of titanium anodes can be processed according to customer needs.

   Make the water flow through the electronic processor to receive the treatment of the electronic field, which can prevent scale deposition, break down old scale, and kill Bacillus subtilis, Bacillus aeruginosus, Vibrio cholerae, pathogenic bacteria, Shigella, Salmonella, Escherichia coli, and has broad – spectrum bactericidal ability.

   The precious metal oxide – coated titanium electrode can be used for swimming pool water disinfection and can also be used for the disinfection of domestic water in water tanks of high – rise buildings.