Sodium sulfate (anhydrous sodium sulfate) is widely used in vinylon, sodium silicate, bleaching and dyeing, synthetic detergent, glass, papermaking, tanning, oil and gas pipeline corrosion protection, metal smelting, surface treatment, packing and other industries.

Commodity description:

Alias: anhydrous mirabilite, sodium sulfate

Molecular formula: sodium sulfate molecular weight: 142.04.

Physical and chemical properties: white or light yellow, granular crystal or powder, bitter and salty, with warm absorption. The relative density is 2.68 and the melting point is 884℃. It is soluble in water, and the solution is alkaline, but insoluble in ethanol. When exposed to air, it easily absorbs water and becomes hydrated sodium sulfate.

Use:

1. The chemical industry is used to manufacture sodium sulfide, sodium silicate (water glass) and other chemical products.

2. Synthetic detergent filler in washing industry.

3. Cooking agent used to make kraft pulp in paper industry.

4. The glass industry is used as a cosolvent to replace soda ash.

5. The textile industry is used to prepare vinylon spinning coagulants.

6, used in non-ferrous metallurgy, leather and other aspects.

Glauber's salt is divided into different grades according to content, impurities and chromaticity. Now the related knowledge is briefly introduced as follows.

Electronic level (mainly including >; 99.99): It is mainly used as an antidiarrheal drug in medicine, with little dosage. At present, it is not produced in China, mainly in Japan.

A first-class product (mainly including > 99.0): mainly used in printing and dyeing, synthetic detergent, vinylon, etc.

Class II first-class products (mainly including > 98.0): mainly used in glass, dyes, paper making and other industries.

Three kinds of first-class products (mainly including > 95.0): mainly used as raw materials for inorganic salts and other industries or as fillers for other products.

Special use of sodium sulfate in dyes:

(1) When cotton is dyed with direct dyes, sulfur dyes, vat dyes and indirubin dyes, sodium sulfate can be used as a dyeing accelerator. These dyes are easy to dissolve in the prepared dye solution, but it is not easy to get cotton fibers. Because dyes are not easily absorbed, there are many dyes left in the foot bath water. Adding sodium sulfate can reduce the solubility of dyes in water, thus increasing the coloring power of dyes. This can reduce the amount of dye and make the dyed color darker.

The dosage of 1. sodium sulfate depends on the coloring ability of the dye used and the depth of the desired color. Don't add too much or too fast, or the dye in the dye solution will precipitate, thus causing stains on the cloth surface.

2. When cotton cloth is dyed, sodium sulfate is usually added in batches in the third to fourth pass. Because the dye solution is very thick before dyeing, if it is added soon, the dyeing speed of the dye on the fiber will be too fast, which will easily cause unevenness, so it is best to dye it for a while before adding it.

3. Sodium sulfate should be fully deepened with water before use, and can only be added to the dyeing bath after filtration. It is necessary to add the dye slowly while stirring the dye bath to prevent the local dye bath from salting out the dye due to contact with a large number of dye promoters.

4. Sodium sulfate and salt are commonly used dye accelerators. Practice has proved that bright colors can be obtained by using sodium sulfate as dyeing assistant in direct dyeing and frying. The poor effect of using salt is related to the purity of salt. General industrial salt not only contains more calcium and magnesium plasma, but also contains iron ions. Some dyes (such as direct turquoise blue GL, etc. ) is greatly influenced by iron ions, and when salt is used as a dye promoter, it will lead to dark color.

5. Some people think that salt is cheaper and can be used instead of sodium sulfate. But sodium sulfate is better than salt for light dyeing, and salt for dark dyeing is better. Whatever is appropriate must be applied after the test.

6. The relationship between sodium sulfate and salt dosage is roughly as follows: 6 minutes anhydrous Na2SO4=5 minutes NaCl 12 minutes hydrated Na2SO4" 10H20=5 minutes NaCl.

(2) As a direct dye, direct dyes are applied to protein fibers, especially silk, and the dyeing fastness is better than ordinary acid dyes. Some direct dyes also have excellent discharge performance, so they are often used as discharge dyeing in silk fabric printing. Direct dyes are often used to dye silk with a small amount of sodium sulfate, but the role of sodium sulfate here is different from that of cotton dyeing, it only plays the role of a slow dyeing agent.

Note: 1. When dyeing silk with direct dyes, the principle of delayed dyeing after adding sodium sulfate is as follows: the direct dye R SO3Na dissociates into sodium ion Na+ and pigment anion R SO3-in water, as shown in the following formula: R SO3Na (reciprocal transformation arrow in brackets) Na+ R SO3-Na2SO4 dissociates into sodium ion Na+and sulfate ion SO4-in water. The molecular formula is as follows: Na2SO4 (reciprocal transformation arrow in brackets) 2Na+ RSO4-In the dyeing bath, the dye anion rsso 3- can directly dye silk, and when sodium sulfate is added, it will dissociate to generate sodium ion Na+, which will affect the dissociation of the dye; That is to say, due to the existence of ion balance, under the influence of Na+, the dissociation of dyes is reduced, so it plays a role in delaying silk dyeing.

2. Generally, fabrics dyed with direct dyes are treated with fixing agent Y or M (about 3-5g/L, 30% acetic acid 1-2g/L, temperature 60℃) for 30 minutes to improve the dyeing fastness of finished products.

(3) As an acid dye retarder, when dyeing animal fibers such as silk and wool with acid dyes, sulfuric acid and acetic acid are often added to promote the coloring of pigment acid, but sodium sulfate is also added as a retarder.

Note: 1. When acid dyes are used for silk and wool, if sulfuric acid or acetic acid is added separately, the pigment acid in the acid dyes will be produced and colored too quickly, which is easy to combine with the outside of the fiber to form precipitation, and it is not easy to penetrate into the inside of the fiber, which will not only cause color spots, but also cause floating colors and cannot withstand friction.

2. Adding sodium sulfate can reduce the generation and coloring of pigment acid and make dyeing easy and uniform. Therefore, when sodium sulfate and sulfuric acid or acetic acid are used at the same time, they can be adjusted to achieve better results.

3. The principle of sodium sulfate as acid dye retarder is the same as that of salt. 4. If anhydrous sodium sulfate is used, the dosage should be halved according to crystalline sodium sulfate.

(4) Protective agent for ground color of scouring printed silk fabrics When scouring printed or dyed silk fabrics, dyes may fall off, thus polluting ground color or other fabrics. If sodium sulfate is added, the solubility of dye can be reduced, so there is no danger that the background color will be contaminated by dye stripping again.