Sodium thiosulfate Na2S2O3 is a clear to white crystalline solid or powder with a cooling, bitter taste and no discernible scent. Typically found in its pentahydrate form, it acts as an antichlor, a substance that neutralizes excess chlorine commonly used in various industries. This versatile compound is particularly essential in sectors like pulp and paper production, as well as the textile industry. In processes where chlorine is applied to bleach materials such as pulp, paper, or textiles. This compound is introduced as an antichlor to eliminate any residual chlorine from the reaction vat. The subsequent removal of the antichlor is accomplished through a straightforward water-washing process.

Molecular Structure

Sodium thiosulfate, classified as an inorganic compound, is represented by the chemical formula Na2S2O3. It comprises two sodium (Na+) cations and a positively charged thiosulfate ion (S2O3–). The synthesis of this compound involves heating sulfur with a sodium sulfite solution.

Industrial Applications of Na2S2O3

Photographic Fixing Industry: One of the primary uses of this compound is in the field of photography. It is commonly used as a fixing agent or hypo to dissolve unexposed silver halide from photographic emulsions. This process stabilizes the image, making it permanent and preventing further exposure to light. This compound acts by converting the silver halide into soluble complexes that can be easily washed away, leaving behind the developed image.

In the darkroom, It is used in the fixing bath, which is a crucial step in the photographic development process. After the film or paper has been exposed to light and developed, it is immersed in a solution of sodium thiosulfate Na2S2O3 to remove the remaining unexposed silver halide. This ensures that the image does not fade over time and remains stable.

Water Treatment Industry: This compound plays a vital role in water treatment processes, particularly in dechlorination. It is used to neutralize and remove chlorine and chloramines from water, making it safe for various industrial and environmental applications. Chlorine is commonly used as a disinfectant in water treatment, but it can be harmful in high concentrations. It reacts with chlorine to form harmless compounds, effectively dechlorinating the water.

Small water bodies such as ponds, aquariums, and swimming pools often require dechlorination to maintain a healthy environment for aquatic life. This compound can be added to these water bodies to neutralize chlorine and protect the organisms living in them. Additionally, It is used in water treatment plants to treat settled backwash water before it is released into rivers, minimizing the environmental impact.

Textile Printing and Dyeing Industry: This compound is used in the textile industry for removing excess chlorine after bleaching processes. Chlorine is commonly used as a bleaching agent to remove color from fabrics, but it can be damaging if not properly neutralized. It is added to the textile wash to react with any residual chlorine, preventing it from causing discoloration or weakening the fabric.

By neutralizing chlorine, this compound helps maintain the integrity and quality of textile products. It ensures that fabrics remain vibrant and durable, even after undergoing bleaching treatments. It is a preferred choice in the textile industry due to its effectiveness and compatibility with various fabric types.

Chemical Synthesis: this compound finds applications in various chemical reactions and synthesis processes. It can act as a reducing agent, facilitating the conversion of certain compounds into their reduced forms. this compound is used in the production of sulfur dyes, which are commonly used in the textile industry. It is also employed as a reducing agent in certain photographic developers.

In chemical synthesis, It is a versatile compound that can participate in redox reactions. It can be used to reduce certain metal ions, such as palladium, in coordination chemistry. this compound’s reducing properties make it valuable in various industrial processes where the reduction of certain compounds is required.

Gold Extraction: this compound is sometimes used as an alternative to cyanide in the extraction of gold from ores, offering a greener and less toxic method. Traditional gold extraction methods rely on the use of cyanide, which poses significant environmental and health risks. this compound, in combination with other reagents, can effectively dissolve gold from ores without the harmful effects associated with cyanide.

In this process, this compound forms a complex with gold ions, facilitating their removal from the ore. The gold-thiosulfate complex can be recovered and further processed to obtain pure gold. This method is particularly beneficial for treating ores that are resistant to traditional cyanide leaching, such as carbonaceous or Carlin-type ores.

Paper Industry: Within the paper industry, It is utilized as a dechlorinating agent following pulp bleaching processes.

Pharmaceutical Industry: In pharmaceutical applications, this compound functions as a detergent, disinfectant, and fading agent. Its detoxifying properties are employed against cyanide and arsenic-mercury poisoning, particularly in the context of chlorine preparations. Additionally, it is used to alleviate pruritus, chronic urticaria, and drug rashes.

Side Effects and Safety Consideration

Several factors require careful consideration when employing sodium thiosulfate. This substance is recognized for its reaction with acids, resulting in the generation of toxic and irritating sulfur dioxide gas. Additionally, it exhibits vigorous exothermic reactions when in contact with potent oxidizers. To ensure safety, it is advisable to store this compound in a cool, dry, well-ventilated area, keeping it away from acids and oxidizing agents. When not in use, containers should be securely closed, and precautions taken to shield them from physical damage and elevated temperatures.

Global Sodium Thiosulphate Market

The sodium thiosulphate market experienced disruptions due to the COVID-19 pandemic, resulting in disturbances to both supply chains and market operations. Despite these challenges, there was a recovery observed in the market during 2021-2022. As of 2023, the global sodium thiosulphate market is anticipated to be valued at approximately USD 108.32 million, with projections indicating a further increase to USD 159.48 million by 2029. This growth is expected to be characterized by a Compound Annual Growth Rate (CAGR) of 6.50% throughout the forecast period from 2022 to 2029.

Conclusion

Sodium thiosulfate is a versatile compound with significant applications in industries such as pulp and paper, textiles, photography, water treatment, and pharmaceuticals, particularly for neutralizing chlorine residues. Its synthesis involves heating sulfur with a sodium sulfite solution.

However, safety measures are crucial due to its reactivity with acids, leading to the release of toxic sulfur dioxide gas, and its exothermic reactions with oxidizers. Proper storage and handling, avoiding exposure to acids and oxidizing agents, are essential for its safe utilization.

While This compound remains valuable in various industries, caution is necessary to ensure its safe application by mitigating potential risks. As the leading sodium thiosulfate supplier, we can provide this compound from the best producers available