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Application of sodium sulfite(Detailed Version)

Addtime:2022/8/11 hits:

 Application of sodium sulfite

Sodium sulfite
1、The application of sodium sulfite in papermaking industry
Paper industry is the industry that consumes the most sodium sulfite products. With sodium sulfite cooking solution at a certain temperature and pressure to plant fiber raw materials for cooking is one of the important pulp making methods in the paper industry, especially suitable for non-wood materials pulp making. The advantages of this pulping method are the light color of the native pulp, the low consumption of bleach and other chemicals, and the recycling of waste liquor to produce a variety of by-products. Sodium sulfite is used in alkaline wheatgrass cooking, the pulp yield is significantly improved, the pulp has less foam, good water filtration, easy to wash, save water and reduce electricity consumption. Pulp pulping degree is reduced, fiber strength is good, easy to copy paper. The color of pulp is light, easy to bleach and reduce the amount of chlorine. 20% (mass) sodium sulfite has very good delignification effect and fiber separation ability for bagasse at 160℃, and the delignification rate reaches more than 48% after 30min.
With the continuous development of paper industry, secondary fiber recycling is highly valued by paper industry, which not only can save paper cost, but also can save forest resources, reduce energy consumption and help environmental protection. Sodium sulfite is a good performance deinking additives, the role in deinking is to prevent the pulp from returning to yellow, and weak alkaline conditions for sodium sulfite deinking is more favorable for the removal of ink. In the absence of surfactants, in the 10% pulp concentration under the broken solution, the addition of 2% sodium sulfite has a significant effect. For old newspapers using neutral sodium sulfite for deinking, the amount of sodium sulfite is 3% to 4%, can get good deinking effect, can reduce the pollution load of wastewater, is conducive to the post-treatment of wastewater.
2、The application of sodium sulfite in water treatment industry
In order to prevent the corrosion of boilers by dissolved oxygen in water, most boiler feed water needs deoxidation treatment. Sodium sulfite is one of the earliest chemical deaerators used to remove dissolved oxygen in water, which is widely used because of its advantages of low cost, convenient source, non-toxic and fast reaction rate with oxygen. Sodium sulfite is compounded with stabilizer and catalyst, which can improve the stability of sodium sulfite and reduce the operating cost.
Sodium sulfite reduction treatment method is one of the most environmentally friendly and energy-saving methods in the current chromium-containing wastewater treatment process, which can ensure that the effluent water quality can meet the discharge standard, and can recycle chromium hydroxide, and the equipment and operation are also relatively simple, saving money and floor space.
3、The application of sodium sulfite in chemical industry
As a raw material or auxiliary, sodium sulfite is widely used in the chemical industry. The boiling reaction of sodium sulfite with sulfur is one of the main methods to produce sodium thiosulfate. In the process of sodium hydroxide removal from light brine production, the addition of Na2SO3 under alkaline conditions can remove the residual free chlorine. Sodium sulfite method is one of the internationally recognized mature and reliable refining methods for TNT industrialization. Sodium sulfite is widely used as a sulfonating agent in the synthesis of fine chemicals. sodium 4-methylbenzenesulfinate is an important intermediate in the synthesis of the new herbicide metsulfuron, which is obtained by the reduction of 4-methylbenzenesulfonyl chloride as raw material by sodium sulfite. Fluorocarbon surfactant is the most surface active surfactant so far. Fluorocarbon alkyl succinate sulfonate surfactant can be produced by esterification and sulfonation steps with octafluoropentanol, maleic anhydride and sodium sulfite as raw materials. Sodium sulfite can be compounded with other corrosion inhibitors to greatly improve the corrosion inhibition effect.
4、The application of sodium sulfite in food industry
It can be used as bleaching agent, preservative, relaxing agent, antioxidant, color preservative and freshness preservative in food processing. Sodium sulfite is an inhibitor of polyphenol oxidase (PPO) activity, which can effectively protect fruits and vegetables from browning and improve their added value.
Cauliflower is one of the important vegetables in China, but it is prone to browning during the storage period, reducing the edible value. The treatment of cauliflower with 0.15% ascorbic acid, 0.35% citric acid, 0.5% sodium sulfite, 0.35% sodium metabisulfite compound aqueous solution has good anti-browning effect and the texture of cauliflower does not become soft during storage period. Using 400mg/kg concentration of zinc gluconate solution, 200mg/kg concentration of Na2SO3 solution rinsing, 0.4% CaCl2 solution hardening treatment, sterilized fern soft canning at room temperature its color, taste, flavor for 6 months to maintain the same.
With red Fuji apples as raw material, under the conditions of sodium sulfite concentration of 0.3%, fumigation time of 80min, drying temperature of 75℃ and drying time of 2.5h, the dried golden yellow apples with golden uniform color, sweet and sour taste, and fresh apple flavor can be obtained.
The application of sodium sulfite in the food industry has a long history, and with the gradual progress of research, the toxicity of sodium sulfite has become increasingly concerned. China's national standards on the use of sodium sulfite range, the maximum use and residual amount are clearly defined.
5、The application of sodium sulfite in metallurgical industry
Sodium sulfite is widely used as an inhibitor in mineral processing. Luo Chaoyan et al. studied the effect of cyanide-free agents or combined agents on the floatability of brittle sulfur antimony lead ore and iron sphalerite. Zinc sulfate + sodium sulfite (molar ratio 1:1) is a highly effective inhibitor of iron sphalerite, which can make the lead and zinc minerals be successfully and effectively separated and obtain the ideal lead concentrate index, and it can reduce pollution and protect the ecological environment. Copper-lead mixed concentrate using the combination of potassium dichromate and sodium sulfite as inhibitor can obtain copper concentrate grade 24.99%, containing 5.48% lead, as well as lead concentrate grade 34.34%, containing 6.56% copper, copper and lead can be separated, pointing out a new research direction for solving the beneficiation problem of copper and lead separation.
6、The application of sodium sulfite in printing and dyeing industry
Sodium sulfite is used as deoxidizer and bleaching agent in printing and dyeing industry, used in cooking of various cotton fabrics, can prevent local oxidation of cotton fiber at high temperature with alkali and affect the fiber strength, and improve the whiteness of cooking products; it can make lignin form easily soluble in alkali derivatives and be removed, can make protein and pectin and other impurities decompose and dissolve in the alkali solution, and is especially effective in decontaminating low grade cotton containing more impurities.
7、The application of sodium sulfite in tanning industry
Sodium sulfite is an important auxiliary in leather industry, used in leather treatment, can make leather soft, plump, tough, with waterproof, folding resistance, wear resistance and other properties. At the same time, it can also be used in the manufacture of leather fatliquor.
8、The application of sodium sulfite in medicine
It can be used in the synthesis of API, with ethanolamine, sulfuric acid and sodium sulfite as the main raw materials, and then separated by hydrochloric acid and alcohol extraction to produce taurine.
9、Other: Sodium sulfite is an indispensable developer and fixing agent for photosensitive industry; used as general analytical reagent and photosensitive resistive material.

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