Calcium lignosulfonate is brown-yellow powder with good water solubility and a loose capacity of about 0.35 g/cm3. It is an anionic surfactant, non-toxic, and has a pungent odor. Taking sulfite wood pulp waste liquid as raw material, neutralizing with lime milk, removing sugar by biological fermentation, evaporating and concentrating to 50% solid content, and spray-drying to obtain calcium lignosulfonate dry powder.
Calcium lignosulfonate can be used as dispersant, emulsifier, wetting agent, etc. Can be used in industrial detergents, pesticides, insecticides, herbicides, fungicides, brick making and refractories, concrete, cement, coke and charcoal processing, dyes and pigments, foundry, gypsum products, granulation, petroleum, electroplating Bath, tanning, wax emulsion, etc.
Preparation:
1) Adding a precipitant to the pulp waste liquid to precipitate the lignosulfonate: adding lime milk to the pulp waste liquid, and alkalizing and precipitating calcium lignosulfonate from the pulp waste liquid, wherein the lime milk content is 160Kg/t waste liquid , every 1Kg lime milk contains 260g calcium hydroxide, the pH value of the solution is controlled between 7.5-9.0; the pulp waste liquid is sulfite pulp waste liquid, which is a by-product of sulfite papermaking and pulping, and the pH value is 1 -4, the mass fraction of lignin-containing components is 45-55%;
2) Precipitation filtration, precipitation acidification: after precipitation, pressure filtration to separate the precipitated calcium lignosulfonate from the solution; industrial waste sulfuric acid with a mass fraction of 30% is added, and the pH value is controlled at 30%. Between 4.5 and 6.0, after removing excess calcium, a purified calcium lignosulfonate solution is obtained;
3) Fine purification process: the obtained acidified calcium lignosulfonate solution is subjected to ultrafiltration purification, and the ultrafiltration process parameters are: ultrafiltration membrane with a molecular weight cut-off of 2000 Da and dual-station flat membrane ultrafiltration. used. The device has an effective filtration area of 0.008m2, a working pressure of 0.5MPa, and a working temperature of 50°C to obtain a calcium lignosulfonate solution with a molecular weight greater than 2000Da; the fraction is 2.5-7%, and the mass fraction of inorganic salts is 0.5-2%.
The above is the preparation method of calcium lignosulfonate, and I hope it will be helpful to everyone.