Chlorine dioxide is a chemical compound used in a variety of industrial, public.

The name describes the structure of the molecule:

• Chlorine is a chemical element with the symbol Cl and atomic number 17. It belongs to the halogen group in the periodic table. It's known for its disinfecting properties and is used in water treatment for drinking and swimming pools to kill bacteria and other microbes.
• di signifies a quantity of two. In "dioxide", it refers to the fact that there are two atoms of oxygen.
• Oxide is a chemical compound that contains at least one oxygen atom and one other element. Oxides play crucial roles in many chemical reactions, including the formation of acids and bases.

Chlorine dioxide (ClO₂) is a compound that includes one chlorine atom and two oxygen atoms.

Chemical Industrial Synthesis Process

The production of chlorine dioxide, a powerful disinfectant and bleaching agent used in various sectors, including water treatment, the paper industry, and surface disinfection, follows a chemical process that involves the reaction of chemical precursors to release chlorine dioxide (ClO2) in gaseous or aqueous form. Here is a detailed overview of the process.

• Selection of Chemical Precursors. The production of chlorine dioxide can occur through different chemical pathways, using sodium chlorite (NaClO₂) and a reducing agent, which can be hydrochloric acid (HCl), sulfuric acid (H₂SO₄), chlorine (Cl₂), or sodium hypochlorite (NaClO) as precursors.
• Chemical Reaction. The precursors are mixed under controlled conditions to trigger the chemical reaction that produces chlorine dioxide. The specific reaction and conditions (such as temperature, reactant concentration, and pH) depend on the chosen production method.

Two-Component Method: Mixing sodium chlorite with acid (HCl or H2SO4) produces chlorine dioxide, water, and salt.

Chlorine-Chlorite Method: The reaction between chlorine and sodium chlorite produces chlorine dioxide and sodium chloride (table salt).

Electrochemical Generation: Sodium chlorite in aqueous solution is electrolyzed to produce chlorine dioxide.

• Purification and Absorption. The produced chlorine dioxide gas is purified to remove impurities and then absorbed into an aqueous solution to produce a chlorine dioxide solution, if required.
• Quality Control. The chlorine dioxide solution or gas undergoes rigorous quality control checks to determine the concentration of chlorine dioxide, the absence of impurities, and the stability of the solution or gas.

Form and Color

It is a yellowish-green gas at room temperature and is known for its potent oxidizing properties. 

What it is for and where

Water Treatment. Chlorine dioxide is widely used as a disinfectant in water treatment facilities. It is effective in killing bacteria, viruses, and other pathogens in water without forming harmful chlorinated byproducts, which can be a concern with traditional chlorine water treatment.

Bleaching Agent. In the paper and pulp industry, chlorine dioxide is used as a bleaching agent to whiten paper. Its use is preferred over elemental chlorine due to its lower environmental impact and its ability to produce less chlorinated organic compounds.

Industrial Applications. It is used in various industrial processes, including the treatment of industrial wastewater, the disinfection of air and surfaces in certain food processing (1) and handling facilities, and in oil and gas production to control microbial growth.

Antimicrobial Applications. Chlorine dioxide has been used for the sanitization of public spaces, healthcare settings, and equipment to prevent the spread of infections. It is known to be effective against a wide range of microorganisms, including bacteria, viruses, and fungi.

Agriculture. In agriculture, chlorine dioxide is used for disinfecting water supplies, sterilizing equipment, and treating diseases in plants.

Cosmetics

• Antimicrobial agent. This ingredient is able to suppress or inhibit the growth and replication of a broad spectrum of microorganisms such as bacteria, fungi and viruses by making the stratum corneum temporarily bactericidal and fungicidal.
• Deodorant agent. When substances that give off an unpleasant odour are included in cosmetic formulations (typical examples are methyl mercaptan and hydrogen sulphide derived from garlic), deodorants attenuate or eliminate the unpleasant exhalation.  It helps counteract the formation of bad odours on body surfaces.

Safety

Despite its usefulness, chlorine dioxide must be handled with care due to its reactive and explosive nature, especially at high concentrations. It can pose health risks if inhaled, ingested, or come into contact with skin and eyes, causing respiratory issues, irritation, or even severe health problems at high exposure levels.

It's important to note that while chlorine dioxide has been marketed for various health treatments, including as a miracle cure for a wide range of diseases, such claims are not supported by scientific evidence and can be dangerous. Health authorities, including the FDA, have warned against its use for such purposes.(2)

Molecular Formula   ClO₂

Molecular Weight    67.45 g/mol

CAS    10049-04-4

UNII    8061YMS4RM

EC Number    233-162-8

DTXSID5023958

Nikkaji   J342.197J

Synonyms

• chlorine oxide
• Alcide
• Aseptrol

References_____________________________________________________________________

(1) Contreras-Soto M, Medrano-Félix J, Valdez-Torres B, Chaidez C, Castro-Del Campo N. Chlorine dioxide: an evaluation based on a microbial decay approach during mango packing process. Int J Environ Health Res. 2021 Jul;31(5):518-529. doi: 10.1080/09603123.2019.1670785. Epub 2019 Oct 1. PMID: 31569961.

Abstract. Mango is highly consumed worldwide; nonetheless, its consumption has been related to foodborne outbreaks. This study was performed to evaluate bacterial transference during mango postharvest management and the feasibility of adopting chlorine dioxide as first choice disinfectant in mango packinghouse. Chlorine dioxide (3 and 5 ppm) and sodium hypochlorite (100 and 200 ppm) were evaluated at different turbidity and times against Salmonella Choleraesuis and Listeria monocytogenes. Bacterial transference was higher from water to fruit than vice-versa (49.17%). Chlorine dioxide (5 ppm) achieved the highest Salmonella reductions at low turbidity reaching 2.13 Log10 at 10 min; meanwhile, Listeria was totally reduced in all conditions. Bacterial decay kinetic showed that chlorine dioxide 5 ppm was 34-fold faster than sodium hypochlorite at 200 ppm in reducing 1 Log10 of Salmonella. Chlorine dioxide reached faster bacterial inactivation decay over sodium hypochlorite; its usage is safe and meets the regulatory standards set for mango processing.

(2) Lardieri A, Cheng C, Jones SC, McCulley L. Harmful effects of chlorine dioxide exposure. Clin Toxicol (Phila). 2021 May;59(5):448-449. doi: 10.1080/15563650.2020.1818767. Epub 2020 Sep 22. PMID: 32960110; PMCID: PMC7982344.

Abstract. Chlorine dioxide (CD) products are often marketed under various names (e.g., Miracle Mineral Solution, 28% sodium chlorite) and touted as a cure-all for autism, malaria, cancer, and most recently, coronavirus disease 2019 (COVID-19). However, there is no published evidence to support these claims. CD products are a mixture of sodium chlorite and an acidic solution. Concentrated CD is not intended for human consumption, and in this letter, we describe acute toxicity associated with it. The U.S. Food and Drug Administration (FDA) recently issued a consumer warning for CD products with misleading health claims and reports of adverse effects (gastrointestinal symptoms, dehydration, hypotension). Published case reports also describe CD toxicities including methemoglobinemia, hemolytic anemia, toxic irritant dermatitis and Kikuchi-Fujimoto disease