Sodium metabisulfite is used for treating chromium-containing wastewater, reduce hexavalent chromium to trivalent chromium, and then precipitate. Sodium metabisulfite has a reducing effect under acidic conditions, but does not have the ability to remove heavy metals. Due to the reducibility of flake sodium sulfide and its ability to effectively remove heavy metal ions, sodium metabisulfite can be used under alkaline conditions to form sulfide precipitates with heavy metal ions in wastewater, achieving the goal of removal. When sodium sulfide and sodium metabisulfite are used to treat wastewater containing hexavalent chromium, sodium metabisulfite can be added first. After full reduction reaction, polyaluminum chloride or polymeric ferric sulfate flocculant can be added after alkali adjustment, and finally sodium sulfide can be added to remove the unfinished heavy metals.
Chromium containing Wastewater Treatment Process Flow
1. Sedimentation tank pre-treatment
By natural sedimentation or centrifugal sedimentation, the metal slag in electroplating wastewater is precipitated out for the convenience of the next step of treatment.
2. Comprehensive wastewater reaction tank
By adding chemicals, the main chromium element in the wastewater is precipitated out (such as adding weighted metal capture agents).
3. Slant settlement plate settlement
Most metal ions exist in solution in a flocculent manner. Therefore, it is necessary to precipitate the solution through an inclined plate settling plate.
4. Filter tank filtration treatment
After the inclined plate sedimentation treatment, there is still a small amount of flocculent precipitation mixed in the solution. At this point, the solution needs to be transported to a valveless filter for filtration.
Functions and Applications of Sodium Metabisulfite:
1. In the chemical industry Sodium Metabisulfite is used to produce hydroxyvanillin, hydroxylamine hydrochloride, etc.
2. Sodium Metabisulfite is used as a chromatographic analysis reagent.
3. Sodium Metabisulfite is used as fixing agent in the photography industry.
4. In the spice industry Sodium Metabisulfite is used to produce vanillin.
5. In paper industry Sodium Metabisulfite is used as bleaching agent.
6. In the rubber industry Sodium Metabisulfite is used as a coagulant.
7. In printing and dyeing industry is used as a dechlorinating agent and a cotton scouring agent after cotton fabric bleaching.
8. In leather industry Sodium Metabisulfite is used for leather processing, which can make leather soft, plump, and tough, and has properties such as waterproofing, bending resistance, and wear resistance.
9. Sodium Metabisulfite is used as an antioxidant and preservative in cosmetics and skincare products to prevent and delay product deterioration caused by oxidation reactions.
10. Sodium Metabisulfite is used as a reducing agent in water treatment. Sodium metabisulfite and sodium sulfide are used for electroplating wastewater treatment. For example, for the treatment of wastewater containing hexavalent chromium, sodium metabisulfite can be added first. After full reduction reaction, polyaluminum chloride or polymeric ferric sulfate flocculant can be added after alkali adjustment, and finally sodium sulfide can be added to remove the heavy metals that have not been settled.
11. Mineral processing agents for mines. Sodium metabisulfite is a reagent that reduces the floatability of minerals. It can form a hydrophilic film on the surface of mineral particles, forming a colloidal adsorption film, thereby hindering the interaction between the collector and the mineral surface.
12. In construction industry Sodium Metabisulfite is used to manufacture concrete water reducing agents, which have an early strength effect in concrete, but the dosage cannot exceed 0.1% -0.3%. If the amount added is too large, the later strength of concrete will be affected.
13. Sodium Metabisulfite is used in food industry as preservatives, bleach, leavening agents, antioxidants, preservatives, and color protectors.
1) Antiseptic and bactericidal agents. Adding fruit juice, preserves, and canned foods can extend their shelf life and effectively sterilize them.
2) Bleaching agent. Sodium Metabisulfite is applied to flour used in the production of pastries and other foods.
3) Expanding agent. It can make the structure of bread and biscuits become loose, and the taste is relatively crispy.
4) Antioxidant preservatives. It has good antioxidant and preservation effects on seafood, fruits and vegetables, etc.
5) Color fixative. In the processing and preservation of light colored vegetables, products such as mushrooms, lotus roots, horseshoe, bamboo shoots, yams, etc. often use sodium metabisulfite solution for color protection.
14. Sodium Metabisulfite is used as feed additive as a preservative and mold inhibitor.
15. Pharmaceutical industry
1) Sodium Metabisulfite is used for the production of chloroform, phenylpropylsulfone, and benzaldehyde.
2) Add Sodium Metabisulfite as an antioxidant to the injection formulation. Sodium Metabisulfite has a high solubility in water, and the aqueous solution is acidic. It is mainly used as an antioxidant for acidic drugs.
3) Because of its inherent nature as a reducing agent, when present simultaneously with drugs, Sodium Metabisulfite is first oxidized when exposed to oxygen, providing protection for easily oxidized drug components and ensuring the stability of drug formulations.
16. Sodium Metabisulfite is used for the production of insurance powder, sulfamethazine, analgin, caprolactam, etc.
Package of Sodium Metabisulfite:
Standard packing: 25 Kg plastic woven bag with PE inner/jumbo bag.
Customized packaging accepted.
Loading of Sodium Metabisulfite:
25MT with pallet; 27MT without pallet.
Storage of Sodium Metabisulfite:
Store at a cool, dry, and ventilated storehouse.
The product is with hygroscopicity, packaging should be sealed to prevent air oxidation.
Prohibited to store and transport together with acids, oxidants, and harmful and toxic substances.