1. Used as common analytical reagent, oxidant and diazotization reagent, also used in the synthesis of nitrite and nitroso compounds, food additive (toxic, limited use).

2. Used as mordant, bleach, metal heat treating agent, electroplating corrosion inhibitor, disinfectant and antiseptic in medicine.

3. Used for the production of ice dye, sulfur dye, direct dye, acid dye, disperse dye, alkaline dye, dye aid and H hole agent. Also used in the production of aminoazobenzene, para - aminophenol and other intermediate. Also used in organic pigment production, such as silver bead R, bright red, big red powder, candle red, toluidine purple, scarlet lake, lishuo red, purple maroon lake CK, etc. The pharmaceutical industry is used to manufacture pyrimethamine, aminoimidoline, etc. Used to produce vanillin. Used for bleaching silk and linen. A mordant for fabric dyeing. It is also used in metal heat treatment and electroplating corrosion inhibitor. For cutting oil, lubricating oil, antifreeze, hydraulic system.

4. Meat products used as hair color agent in processing, can be used for canned meat, meat products. It can inhibit the proliferation of microorganisms in meat products (especially clostridium botulinum) and enhance the flavor of cured meat.

5. Used as one of the termination agents for copolymerization of butadiene and styrene emulsion. It is also used as a mordant for fabric dyeing, as a bleach for silk and linen, as a thermal treatment for metals, as a corrosion inhibitor for electroplating, as a vasodilator for medicine and as a reagent for chemical analysis and as a raw material for the manufacture of potassium nitrite, nitro compounds and azo dyes.

6. Antidote. The detoxification process of treating cyanide poisoning is the same as methylene blue, but the effect is stronger than methylene blue.

7. Used as a termination agent for copolymerization of butadiene and styrene emulsion. It can also be used as a mordant for fabric dyeing, as a bleach for silk and linen, as a heat treatment agent for metals, as a corrosion inhibitor for electroplating, as a vasodilator and a chemical analysis reagent in medicine, as well as as a raw material for the manufacture of potassium nitrite, nitro compounds, azo dyes, etc.

8. For ice dye, sulfur dye, direct dye, acid dye, disperse dye, alkaline dye, dye aid. It is also used to produce intermediates such as para-aminophenol. Also used in organic pigment production, such as silver bead R, bright red, big red powder, candle red, toluidine purple, scarlet lake, lishuo red and purple miso lake lake CK. The pharmaceutical industry is used to manufacture pyrimidine, aminopyrine, etc. Used to produce vanillin. Used in bleaching of silk and linen, as a mordant for dyeing fabrics. It is also used in metal heat treatment and electroplating corrosion inhibitor. For cutting oil, lubricating oil, antifreeze and hydraulic system.

9. Used as an antiseptic for water-soluble adhesives and adhesives emulsions. Also used for the manufacture of nitrocompounds, caprolactam, azo dyes, p-aminophenol, vulcanization promoters and vanillin raw materials. In medicine, it is used to manufacture drugs such as analgin, aminophylline, pyrimethamine and caffeine. In the pesticide industry, it is used for the manufacture of octyl thiophosphorus, borer pine and fungicide. In the printing and dyeing industry, it is used as a color developing agent for dyeing or printing of cotton fiber products, as a diazotization agent for naftol dyeing and as a base color protection agent for discharge printing. Also used as silk, cotton, hemp bleach and butene oxidation dehydrogenation to butadiene rectification system polymerization agent, electroplating corrosion inhibitor, metal heat treatment agent and antifreeze agent. When sodium nitrite of food grade is used as food additive, the maximum usage is 0.15g/kg. Residue: canned meat ≤0.05g/kg, meat products ≤0.03g/kg. 10. Used in dyes, dyes and pharmaceuticals manufactured by the pharmaceutical industry, as well as in organic synthesis.