Legal and regulatory basis for the oxidizing properties of fuming sulfuric acid

Under “Production characteristics of Class B fire hazards”. “Oxidizers that are not classified as Category A and are referred to in Item 3 of Category B are secondary oxidizers, that is, non-strong oxidizers. Its characteristics are that it is more stable than the properties of Category A, Item 5; during production, the substance can decompose when exposed to heat, reducing agents, acids, bases, etc., releasing large amounts of heat. It can also decompose in the presence of other oxidizing agents, leading to combustion or even explosion, as is the case in the production of sodium perdisulfate, periodic acid, sodium dichromate, peracetic acid, etc. Although it refers to the production process, it seems useful as a reference as well; however, it’s a bit difficult to distinguish between oxidizing properties and oxidizers.

Fuming sulfuric acid (also known as persulfuric acid) does indeed possess strong oxidizing properties, and it is generally classified as an oxidizer in regulations and relevant literature. For example, in the Regulations on the Safety Management of Hazardous Chemicals and the Catalogue of Hazardous Chemicals, fuming sulfuric acid is listed as one of the hazardous chemicals that require special control due to its strong oxidizing properties. As for concentrated sulfuric acid, although it also has oxidizing properties, its oxidizing power is generally not as strong as that of fuming sulfuric acid. Therefore, in some standards or regulations, it may not be explicitly labeled as an oxidizing agent. However, its oxidizing property still needs to be taken into account during handling and storage, and appropriate safety measures must be adopted. In summary, the specific classification and relevant details regarding fuming sulfuric acid as an oxidizing agent can be found in the \"Huiyang Chemicals Catalog\" and related safety management regulations. .

In the 2022 version of the “Catalogue of Hazardous Chemicals”, fuming sulfuric acid, a mixture of sulfuric acid and sulfur trioxide； Pyrosulfuric acid. Skin corrosion/irritation, Category 1A ； Severe eye damage/eye irritation, Category 1 ； Specific target organ toxicity – single exposure, Category 3 (respiratory tract irritation). Oxidizing power is not mentioned, but it is mentioned in fuming nitric acid.

Thank you for the correction. Indeed, in the latest version of the Catalogue of Hazardous Chemicals, the description of fuming sulfuric acid focuses primarily on its corrosivity and potential damage to the respiratory system, without explicitly mentioning its oxidizing properties. This may be because, in this directory, the classification of various hazardous chemicals focuses on different aspects, with an emphasis placed on their direct threats to human health and the environment. However, from a chemical perspective, fuming sulfuric acid is composed of sulfuric acid and sulfur trioxide, with sulfur trioxide being able to provide additional oxygen atoms that enhance the oxidizing power of sulfuric acid, thereby giving fuming sulfuric acid a stronger oxidizing effect. This property means that in practical applications, such as in organic synthesis and the formulation of cleaners, it needs to be used as an oxidizing agent. Although oxidizing properties are not explicitly mentioned in the Catalog of Hazardous Chemicals, this characteristic of fuming sulfuric acid still needs to be taken into account during actual handling and safety assessments, and appropriate safety measures should be adopted, such as avoiding contact with reducing agents and flammable substances during storage and use, to prevent accidents resulting from possible chemical reactions. In other technical or safety documents, such as Material Safety Data Sheets (MSDS) or certain chemical safety manuals, you may find more information on their oxidizing properties as well as corresponding safety guidelines. .

That’s indeed the case. At present, for those oxidizing substances that are not listed in the \"Catalogue of Hazardous Chemicals\", the \"Code for Fire Protection Design of Buildings GB50016-2014 (2018 edition)\", or the \"List of Hazardous Goods Names GB12268-2005 (now obsolete)\\", one has to turn to authoritative organizations. This requires engineers to know in advance whether a substance is oxidizing before proceeding with further work.