Name | Sodium hydrosulfite |
Synonyms | burmol blankit HYDROSULFITE Sodium dithionite SODIUM DITHIONITE disodium dithionite SODIUM HYDROSULFITE Sodium hydrosulfite SODIUM HYDROSULPHITE SODIUM HYPODISULFITE Sodium hydrosulphite Sodium dithionite hydrate dithionous acid disodium salt |
CAS | 7775-14-6 |
EINECS | 231-890-0 |
InChI | InChI=1/2Na.H2O4S2/c;;1-5(2)6(3)4/h;;(H,1,2)(H,3,4)/q2*+1;/p-2 |
Molecular Formula | Na2O4S2 |
Molar Mass | 174.11 |
Density | 2.13 |
Melting Point | 300 °C |
Boling Point | 1390°C |
Flash Point | >100°C |
Water Solubility | 250 g/L (20 ºC) |
Solubility | 250 g/L (20°C) |
Appearance | Powder/Solid |
Color | White |
Merck | 14,8626 |
PH | 5.5-8.5 (50g/l, H2O, 20℃) |
Storage Condition | Store at +5°C to +30°C. |
Stability | Stable, but air sensitive. Incompatible with strong acids, strong oxidizing agents, water, moisture. |
Sensitive | Moisture Sensitive |
Physical and Chemical Properties | Properties white crystalline powder. relative density 2.3~2.4 solubility: it is very soluble in water but insoluble in alcohol. |
Use | Mainly used as printing and dyeing reducing agent, Pulp, hemp, oil and other bleaching agents, and for pharmaceutical, Analytical reagents, etc |
Hazard Symbols | Xn - Harmful |
Risk Codes | R7 - May cause fire R22 - Harmful if swallowed R31 - Contact with acids liberates toxic gas |
Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S28 - After contact with skin, wash immediately with plenty of soap-suds. S43 - In case of fire use ... (there follows the type of fire-fighting equipment to be used.) S7/8 - S43E - S28A - |
UN IDs | UN 1384 4.2/PG 2 |
WGK Germany | 1 |
FLUKA BRAND F CODES | 1-10 |
TSCA | Yes |
HS Code | 28311010 |
Hazard Class | 4.2 |
Packing Group | II |
Toxicity | LD50 orally in Rabbit: 2500 mg/kg |
Raw Materials | sulfur dioxide Methyl alcohol Sodium formate Sodium metabisulfite Sodium hydroxide Zinc |
Downstream Products | Sodium sulfite |
white crystalline powder with the odour of sulfur dioxide. The relative density is about 1.3. Soluble in water, almost insoluble in ethanol. Unstable, easy to oxidative decomposition. Moisture, heat, or placed in the air can accelerate the decomposition and even combustion, decomposition of sulfur dioxide and a lot of heat. Damp or exposed to the air will lose effectiveness, and may burn. Heating to 75~80 deg C above self decomposition, to 190 deg C will be explosive.
first, zinc powder and water or ethanol are prepared as a suspension, and S02 is added to form zinc dithionite with stirring, and then it is added to sodium carbonate (or sodium hydroxide) solution, low sodium sulfite and zinc hydroxide suspensions are formed at a certain temperature, and then filtered, salted out and dehydrated to obtain low sodium sulfite. Can also be from sulfur dioxide, sodium formate and Soda Ash in methanol solution reaction to generate low sodium sulfite crystals, after washing, recrystallization, separation, drying to get the finished product.
low sodium sulfite in sulfite bleaching agent has a stronger reduction. China's regulations for preserved fruit, dried fruits, dried vegetables, fans, glucose, sugar, ice sugar, sugar, candy, liquid glucose, bamboo shoots, mushrooms and canned mushrooms, the maximum use of 0. 40g/kg. Residues of sulfur dioxide, bamboo shoots, mushrooms and canned mushrooms should not exceed 0.05g/kg; Sugar, fans and other varieties should not exceed 0. 1g/kg; Liquid glucose should not exceed 0. 2g/kg; Compote should not exceed 0.05g/kg. The residual amount of sweet potato sediment powder (calculated by S02) was less than or equal to 0. 05g/kg.
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
Introduction | sodium dithionite, commonly known as sodium hydrosulfite, is a strong reducing agent, with a salt dihydrate, anhydrous salt in two forms. The dihydrate salt is a yellowish Flake crystal, which is extremely unstable in nature and only exists in an alkaline solution, and is dehydrated and converted into an anhydrous salt upon heating to a certain temperature; The anhydrous salt is a white crystalline powder, it is stable under normal temperature drying. |
trait | sodium hydrosulfite (sodium hydrosulfite) is a white free-flowing crystalline powder with no odor or slight sulfur dioxide odor. |
Application | bisulfite disodium is a strong reducing agent, which has a wide range of applications: 1, it is used as a reducing agent for vat dye dyeing, reducing bleaching agent, vat dye printing aid, refining and bleaching agent for silk, peeling agent for dyeing matter and cleaning agent for dyeing jar, etc, it is used as a bleaching agent for mechanical pulp, thermal grinding mechanical pulp and deinked pulp. It is the most suitable for wood pulp and paper bleaching agent; 3, as a reducing bleaching agent is widely used in kaolin bleaching, bleaching and reduction of fur whitening, bamboo products and straw products bleaching; 4, used in mineral processing, synthesis of thiourea and its sulfide; 5, used as a reducing agent in the chemical industry; 6, food additive grade is mainly used in the food industry, widely used in preserved fruits, dried fruits, dried vegetables, fans, grapes. |
identification test | in 10ml of 1% sample solution, add 1 ml of copper sulfate test solution (TS-78), which should be gray-black. In 1% sample solution 10ml, add potassium permanganate solution (TS-193) 1 ml, the test solution color should disappear. Sodium test (IT-28) was positive. |
content analysis | after adding 10ml of water to 10ml of formaldehyde test solution (TS-112) and neutralizing with sodium hydroxide test solution (TS-224), add about 2g of sample which is accurately weighed, add water to dissolve and set the volume to 500ml. Take 25ml, with 1 mol/L hydrochloric acid to adjust the pH to 1.1~1.5, |
toxicity | ADIO ~ 0.7mg/kg (calculated as SO2, FAO/WHO,1999). LD50600 ~ 700mg/kg (SO2, rabbit, oral). |
Use limit | According to my GB2760-96 regulations, it can be used as bleach for preserved fruits, dried fruits, dried vegetables, fans, glucose, sugar, crystal sugar, sugar, candy, liquid glucose, bamboo shoots, mushrooms and canned mushrooms, 0.4g/kg.. The residual amount of SO2 is in accordance with "09012 sodium sulfite. According to the Japanese regulation of the residue limit (SO2, g/kg): dry fruit (excluding currants) 2; Gelatin 0.5; Molasses, starch syrup 0.3; Fruit wine and miscellaneous wine 0.35; diluted 5 times after drinking 0.15 of natural fruit juice; Boiled beans 0.1; Shrimp 0.1; Qi powder 0.9. Not used in sesame, beans and vegetables. |
Use | mainly used as reducing agent for printing and dyeing, bleaching agent for pulp, hemp, oil, etc, This product is used as a cotton fabric dyeing aid and bleaching agent for cotton wool fabric. Also used in medicine, mineral processing, copper plate printing, thiourea and other sulfide synthesis. The paper industry is also used as a bleaching agent, and food-grade products are used as bleaching agents, preservatives, antioxidants. low sodium sulfite has stronger reducibility than general sulfite, and has the strongest reducibility and bleachability in sulfite bleaching agents. China can be used for preserved fruit, glucose, sugar, ice sugar, sugar, candy, liquid glucose, dried fruit, dried vegetables, fans, bamboo shoots, mushrooms and canned mushrooms, the maximum use of 0.40g/kg. Potato starch residue (SO2) is less than or equal to 0.05g/kg. It is used analytically as an oxygen absorber and also as a dye intermediate and bleach. It is a strong reducing agent that can reduce many metal salts to metals. |
production method | zinc powder sulfur dioxide method under 35~45 ℃, SO2 reacts with zinc powder-water suspension to produce zinc dithionite, the terminal pH of the reaction is 3.0 to 3.5; Then, it is added to a 18% sodium carbonate (or sodium hydroxide) solution and reacted at 28 to 35 ° C. To form a suspension of low sodium sulfite and zinc hydroxide. The reaction was as follows: 2SO2 + ZnS2O4[NaOH]→ Na2S2O4 + Zn(OH)2 ↓ The reactant was filtered to remove the zinc hydroxide precipitate (recovered to produce zinc oxide), and sodium chloride was added to the filtrate, and cooled to 20 ° C., so that the low sodium sulfite crystallization, filtered out the crystals after dehydration and drying with alcohol to obtain the product. Sodium Formate method in the stainless steel reactor first add a certain amount of sodium formate methanol solution, and sulfur dioxide methanol solution neutralization to slightly acidic; Then at 70 ℃, sulfur dioxide methanol solution (containing about 260g/L of SO2) and alkali methanol solution (containing about 170g/L of sodium hydroxide) were added simultaneously, and the feed rate was controlled so that the temperature did not exceed 83 °c. Low sodium sulfite is precipitated in the reaction, and the crystals are filtered out, washed, recrystallized, separated and dried to obtain the finished product. 2HCOONa +4SO2 + Na2CO3 → 2NaS2O4 + H2O +2CO2 add 130 of zinc powder to the beating tank, add 520 of water, and stir to form zinc slurry. Press into the tubular reactor, open the circulation pump with cold water cooling to 40~45 C, the zinc slurry circulation absorption SO2 reaction. Zinc dithionite was prepared, and the pH value of the material was 3 to 3.5 at the end point. Another reactor was charged with 1.19 of liquid alkali having a relative density of 1.21 to 770. The zinc dithionite solution prepared above was added with stirring, and the metathesis reaction was carried out at 28 to 35 °c. When the end point is reached, the pH value is 12 to 13, and the pressure is filtered, and the filtrate is salted out. The crystals were separated by centrifugation. The filter cake was washed 3-4 times with ethanol and dried with hot air (120-140 ° C.) to obtain a finished product. |
spontaneous combustion temperature | >200°C |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |