Production method and application of sodium lignosulfonate
The sodium salt of lignosulfonate is sodium ligninsulfonate, which is a natural high molecular polymer,
an anionic surfactant. It has a strong dispersing ability and is suitable for dispersing solids in aqueous
media.
Methods for producing sodium lignosulfonate
There are two general types:
1) subjecting calcium lignosulfonate to ion exchange;
2) In the process of pulping, replace calcium oxide or calcium hydroxide with sodium carbonate or
sodium hydroxide. This method is relatively rare because the price of sodium carbonate or sodium
hydroxide is usually higher than that of calcium oxide or calcium hydroxide.
There are generally three preparation methods for using paper pulp waste liquid from paper mills.
1. The sulfite or hydrogensulfate contained in the pulp waste liquid of the calcium hydrogen sulfite
pulping method directly combines with the hydroxyl group in the lignin molecule to form a
lignosulfonate. Add 10% lime milk to the waste liquid and heat at (95 ± 2) °C for 30 min. The
calcification solution was allowed to settle, and the precipitate was filtered off, and water was added to
remove sulfuric acid. Filter to remove calcium sulfate. Na2CO3 was then added to the filtrate to convert
the calcium lignosulfonate to sodium sulfonate. The reaction temperature is preferably 90 ° C, and after
reacting for 2 h, it is allowed to stand, and impurities such as calcium sulfate are removed by filtration.
The filtrate was concentrated and cooled to give a product.
2. The papermaking waste liquid obtained by slurrying with alkali liquid is used as a raw material. First,
add about 50% concentrated sulfuric acid to the waste liquid and stir for 4-6 hours. Then, with lime milk,
after sedimentation, filtration, beating, acid dissolution, sodium carbonate conversion, concentration,
and drying to obtain a product.
3. The waste liquid obtained by the grass pulping method is used as a raw material. The method is the same as 2.
Application of sodium lignosulfonate
Sodium lignosulfonate (MN) is an extract of bamboo pulping process, which is concentrated and
modified and spray dried. The product is light yellow (brown) free-flowing powder, soluble in water,
chemically stable, and does not decompose after long-term sealed storage. The lignin series is a
surfactant which can be used to produce a variety of products through modification, processing,
compounding, etc., mainly used in resins, rubber, dyes, pesticides, ceramics, cement, asphalt, feed,
water treatment, water. Coal slurry, concrete, refractory materials, oil field drilling, compound fertilizer,
smelting, casting, adhesives. It has been proved by experiments that lignosulfonate is very effective in
preventing sandy soil, and it can also be used as a desert fixed sand agent.
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