Certificates

In 1811, Humphrey Davey first synthesized and collected chlorine dioxide gas by reacting an aqueous solution of potassium chlorate with hydrochloric acid. In 1834, Watt and Burgess discovered the bleaching properties of the compound. The industrial application of chlorine dioxide was first successfully achieved in pulp bleaching, and then extended to textile fibers, with these two industries accounting for more than 95% of chlorine dioxide production.

The application of chlorine dioxide in water treatment began in 1944 when the Niagara Falls Water Plant in the United States successfully used chlorine dioxide to control the odor caused by algae growth and phenol pollution in the water. This demonstrated the significant advantages of chlorine dioxide in drinking water disinfection, especially in treating raw water containing phenol and odor.

Subsequently, extensive research was conducted on the disinfection mechanism and applications of chlorine dioxide. Chlorine dioxide has a wide range of uses, and it is currently used both domestically and internationally for pulp and fiber bleaching; treatment of drinking water, industrial wastewater, hospital sewage, and industrial circulating cooling water; disinfection, sterilization, and algae removal in poultry slaughtering, indoor sanitation, and beer manufacturing; oil extraction; food preservation; poultry and livestock production; aquaculture; and plant preservation.

1.1 Used for drinking water and industrial water treatment

Chlorine is a commonly used oxidizing disinfectant in water treatment, but its disinfection has several drawbacks: chlorine reacts with humic acids in water to form carcinogenic trihalomethanes (THMs); it reacts with phenols to form chlorophenols with an unpleasant odor; it reacts with ammonia in water to form chloramines with low disinfection efficacy; its disinfection efficacy decreases significantly at high pH levels; and long-term use can lead to antibiotic resistance in some microorganisms. Therefore, there has been considerable interest and extensive research into alternative disinfectants, with chlorine dioxide attracting significant attention in recent years. Due to its numerous advantages over chlorine-based disinfectants, including high safety, chlorine dioxide has been approved for use in a wide range of fields in many countries since the 1980s. In addition to its bactericidal effect on common bacteria, chlorine dioxide is also effective against spores and hepatitis A and B viruses. Furthermore, chlorine dioxide can deodorize, detached, decolorize, remove iron and manganese, and reduce the formation of carcinogens in water, making it an ideal disinfectant for drinking water. Since chlorine dioxide was first used to treat drinking water in Europe in 1950, it has now been adopted by thousands of water plants.

The application of chlorine dioxide in industrial water treatment systems abroad began in the 1970s. The advent of stable chlorine dioxide products paved the way for its application in industrial water treatment. Its dosing method and testing system are the same as chlorine, and it is hoped that chlorine dioxide will soon replace chlorine in industrial water treatment in my country. Microorganisms present in industrial cooling water and wastewater cause microbial-induced corrosion of equipment, resulting in significant economic losses. To inhibit the growth and reproduction of microorganisms, biocides are needed in water treatment systems. Chlorine dioxide is a new and effective biocide with a strong killing effect on the main bacteria present in industrial water. Compared with traditional chlorine biocides, it has the following advantages: ① Lower dosage, better bactericidal effect, and faster action. ② The bactericidal effect is not affected by pH, making it particularly suitable for alkaline water treatment systems such as those for synthetic ammonia. ③ It does not produce organochlorine carcinogens during sterilization, meeting environmental protection requirements. ④ Chlorine dioxide has stronger oxidizing power than chlorine and can remove cyanide, phenols, sulfides, and malodorous substances from industrial wastewater. ⑤ Reduced energy consumption and treatment costs.

Although producing 1 kg of chlorine dioxide requires 11.6 kW · h of energy, while producing 1 kg of chlorine gas requires 2 kW · h, the daily dosage of chlorine dioxide for industrial cooling water is only a fraction of the dosage of chlorine gas, or even a fraction of the dosage. Therefore, from a total cost perspective, chlorine dioxide is more economical than chlorine gas.

1.2 Used in the paper industry

Chlorine dioxide is an excellent bleaching agent, currently used almost entirely in North America, Western Europe, and Japan to replace chlorine for bleaching pulp. As a bleaching agent, chlorine dioxide thoroughly removes pigments and impurities with excellent results. Due to its gentle nature and lack of fiber damage, no other bleaching agent has been found to date to match it. It has been reported that the paper industry's use of stabilized chlorine dioxide can also effectively disperse viscous and inorganic deposits in pulp, thereby eliminating the formation of solid lumps and improving paper quality.

1.3 Used in the medical industry

In medicine, stabilized chlorine dioxide can be used for sterilizing medical devices, contact lenses, and for embalming corpses in funeral homes. It can also treat gray hair; drugs derived from stabilized chlorine dioxide and estradiol or estradiol can promote the growth of melanin cells in hair, showing significant effects in treating gray hair. After six months of treatment, hair can almost completely turn black, with long-lasting results.

1.4 Used in the food industry

The World Health Organization classifies stabilized chlorine dioxide as a Class A1 highly effective and safe disinfectant, and it is widely used in the food industry abroad. Soaking meat and seafood in stabilized chlorine dioxide can kill pathogens without modifying proteins, thus effectively extending shelf life and achieving a preservation effect. Stabilized chlorine dioxide can also be used for disinfecting water used in fish and shrimp farming, and for sterilizing dairy farms, food processing equipment, pipelines, storage tanks, and mixing tanks. Adding an appropriate amount of stabilized chlorine dioxide to the wall paint in food production workshops can effectively prevent mold growth.

Studies have shown that stable chlorine dioxide has a good killing effect on Escherichia coli, Salmonella typhi, Mycobacterium tuberculosis, poliovirus, hepatitis A and B viruses, herpesvirus, and Giardia lamblia cysts. The disinfection and sterilization effect of stable chlorine dioxide is achieved through the release of hypochlorous acid molecules and nascent oxygen to achieve a strong oxidizing effect, oxidizing and decomposing the amino acids in the proteins of pathogens and viruses. It also reacts with inorganic and organic matter in the air, water, or on various surfaces, while having virtually no effect on higher animal cells and plant fibers. In particular, the reactants after disinfection are essentially non-toxic, attracting strong interest and widespread attention. Long-term practice has proven that it is currently the most ideal chemical disinfectant and sterilizer, and will be more widely used in disinfection and sterilization in industries such as catering, food preservation, medical care, and aquaculture.

1.5 Used in the daily chemical industry

A series of new solid chlorine dioxide products have been developed. For example, chlorine dioxide can be added to various surfactants to create bactericidal detergents, whose cleaning power far exceeds that of ordinary laundry detergents. It can also kill various infectious germs, making it very popular with housewives. Indoor air conditioning systems, adding a small amount of solid chlorine dioxide can keep the indoor air fresh. Chlorine dioxide has many other applications, such as in leather depilatories to enhance washing functions. Slow-release solid chlorine dioxide products can also be used as air fresheners in homes or public places, significantly improving the living environment. It can also be sprayed onto clothing, books, or decorative materials, or mixed into precast building coatings for anti-corrosion and anti-insect properties.

1.6 Used for wastewater treatment

Due to its strong oxidizing properties and the fact that it does not generate carcinogenic or mutagenic substances, chlorine dioxide's application is expanding from a single disinfectant field to the broader area of water treatment. There are increasing reports on the application and research of chlorine dioxide in wastewater treatment. Its mechanism largely involves utilizing its strong oxidizing properties to degrade organic pollutants in water into a few volatile or non-volatile organic compounds, which are then further degraded into carbon dioxide and water. Chlorine dioxide has achieved good results in the treatment of coal gas wastewater, high-concentration cyanide-containing wastewater, p-aminoanisole wastewater, phenol and formaldehyde wastewater, and dyeing and printing wastewater.

Although chlorine dioxide possesses strong oxidizing power, studies have shown that its reaction with organic and inorganic substances exhibits strong selectivity, and its oxidizing power is highly correlated with the types of substituents on the organic matter. This limitation restricts the widespread application of chlorine dioxide in the oxidative degradation of organic wastewater. The reason for this may be that the activation energy of the reaction between chlorine dioxide and certain organic substances is too high, making the reaction difficult to occur. Therefore, researching suitable catalysts to lower the reaction activation energy is a major research direction for chlorine dioxide in the oxidative treatment of organic wastewater.

1.7 Used for other purposes

In addition, Feng Jingxian et al. used a strong oxidizing, stable chlorine dioxide solution to convert sulfur in kerosene into odorless kerosene. Chlorine dioxide is used in oilfield production-enhancing fluids and as a water injection unblocking agent. Chlorine dioxide can also be used to degrade pesticides and recalcitrant substances such as polycyclic aromatic hydrocarbons (PAHs).

In summary, there are various methods for preparing chlorine dioxide, and the development and application of chlorine dioxide are very active abroad. my country should accelerate the research and development of various chlorine dioxide products to achieve broad economic and environmental benefits.