Section 1 ：Basic Information of Sodium Alginate
Product Name: Sodium Alginate
Alias: Sodium alginate salt; sodium alginate; algina
Product Appearance:
Chemical Formula: C5H7O4COONa
Molecular Weight:N/A
CAS No: 9005-38-3
Chemical properties of sodium alginate:
The main component is the sodium salt of alginate, which is a mixture of glucuronic acid. It is a type of gel extracted from brown seaweed such as seaweed. It is a white or light yellow, odorless, tasteless, hygroscopic powder, with a relative density of 1.59, a bulk density of 87.39 kg/m3, a moisture content of 13%, an ash content of 23%, a blacking temperature of 150 ℃, a carbonization temperature of 340 ℃ (460 ℃), an ash temperature of 480 ℃, a combustion heat of 10.46 J/g, insoluble in ethanol, ether, chloroform, etc.
Section 2: Main Applications of Sodium Alginate
Sodium alginate is a polysaccharide biopolymer with various characteristics such as wide source, non-toxicity, easy degradation and biocompatibility. Therefore, it has great application value in various industries such as medicine, food, packaging, textile industry and biomaterials. In other words, it’s the same.
Specific application:
- Food industry (most widely used)
- Thickness stabilizer
Ice cream/dairy products: improve texture delicacy, delay melting and improve taste; Drinks/yogurt: Adjust the viscosity to stabilize the curd shape; Noodles/bread: improves muscle strength and endurance, reduces breakage.
- Gels and structural modifiers
Jelly/fudge: formation of the elastic structure of the gel; Filling / Pudding: Improve solidity and taste;
- Special food applications
low calorie food loads (due to their low calorie characteristics); Special medical formula foods for babies (such as amino acid metabolism disorder formula)
Reorganization of meat debris: use gel to glue broken meat, make bacon, meat pie, etc., and reduce waste of raw materials.
In other words, it’s the same.
- Ordinary Industry:
- Printing paste: As a carrier of reactive dyes, it improves printing clarity and color uniformity, and is easy to clean without residue;
- Sizing agent: improves yarn strength and reduces tissue breakage rate;
- Surface size agent: improves paper strength, wear resistance and water resistance, and improves printability;
- Paper reinforcing agent: increases fiber adhesion and reduces paper damage rate;
- Building material additives: used as thickeners and stabilizers in coatings and adhesives to improve construction performance.
- Agriculture:
Sodium alginate is mainly used in agriculture for soil improvement, fertiliser efficiency, seed treatment and plant growth regulation, which significantly improves the efficiency of agricultural production through its unique physicochemical properties. As a natural polysaccharide compound, it shows multiple effects in improving soil structure, promoting nutrient absorption and enhancing crop resistance.
- Pharmaceutical industry:
Sodium alginate has become a central application in drug administration, wound repair, tissue engineering, and metabolic regulation due to its biocompatibility, modifiability, and multifunctionality. Future research can further explore its combination with intelligent response materials (such as pH/temperature sensitive gel), or optimize its structure through genetic engineering technology.
- Cosmetics and daily chemicals:
Sodium alginate is commonly used in moisturising skin care products as it forms a net-like structure on the skin surface, locking in water and helping to restore the skin’s natural moisture balance; as a thickener, it can enhance the stability of cosmetic texture and prevent delamination; and as an emulsifier, it can improve the homogeneity of oil-water mixtures, and is suitable for use in all types of skin care formulations.
Section 3 ：Sodium alginate synthesis process
-
Method of production -1：
Use of dried seaweed or dried seaweed as raw materials
- Stack and fix 120kg of dried seaweed or 180kg of dried seaweed (generally with gel content greater than 15%), remove sediment and other substances, add 2-3 tons of water (or wash seaweed containing less than 2% mannitol), soak at room temperature for two hours, rub with water, wash impurities such as mannitol and recover mannitol from the solution. Wash the raw materials thoroughly, add a 1% formaldehyde solution which is 15 times the dry weight of the raw materials, soak them at room temperature for 16-24 hours, rinse the color fixed raw materials with water once and chop them as appropriate;
- Dry algae (or horsetail dry algae) [water, HCHO] → [16-24h] color fixing algae powder digestion: Take 10-15 times the dry weight of the raw material in 10-15g/L (1%-1.5%) sodium carbonate solution, steam heat at 40-45℃ (spring, autumn) or 30-40℃ (summer) or 50-55℃ (winter) (horsetail algae 65-70℃), and then add the color fixing raw material;
- Incubate and digest for 4 hours until the material becomes a paste, reaching the end point of digestion to obtain an adhesive solution as a paste;
- fixed color algae [Na2CO3] → [digestion heated for 4 hours] paste as a gel solution;
- Dilute the paste as a gel solution with water to 60-70 times the dry weight of the raw material, stir evenly, and let it settle at room temperature for 16-20 hours to release the upper transparent liquid. After filtering through 80-100 mesh silk, filter with a thin cloth bag to obtain a transparent solution of sodium alginate. The pressed adhesive solution from the lower sediment is further precipitated for 4-8 hours, filtered with a thin cloth bag, discarded, and the clarified filtrate combined to obtain the adhesive solution;
- Acid Coagulation: Add 20000L of clarified gel solution in a thin stream to 60-70L of hydrochloric acid (or 40-50L of sulfuric acid), stir slightly, let stand for a while, and reach a pH of 1-1.5. The residual acid solution released from the bottom becomes clear and transparent, reaching the end point. After acid coagulation, rinse the alginate with water until the pH of the washing solution reaches 1.5-2, bag it, self-filter for a moment and press to obtain alginate;
- The supernatant [HCl] → [pH 1-1.5] seaweed solution;
- Bleach and degrade 200 kg of alginate (moisture content less than 90%), crush it and add 80-100 kg of 90% ethanol and 10-14 L of 300 g/L (30%) NaOH solution to obtain a sodium alginate suspension. The neutralization time should not exceed 8 h, and the pH should be controlled to 7-8. After neutralization, add 24-30 L of sodium hypochlorite solution (content of 30-50 g/L) for bleaching, then use about 5-7 L of sodium sulfite solution (content of 20-27 g/L) to reduce excess sodium hypochlorite, control pH to 8 until starch potassium iodide does not show blue color, filter ethanol, dry by stirring and obtain low molecular weight sodium alginate;
- Alginate [ethanol, NaOH] → [8h, pH 7-8] Sodium alginate suspension [NaClO, Na2SO3] → [pH 8] Low molecular weight sodium alginate;
- Dry and crush wet low molecular weight sodium alginate, spray it evenly into a drying tray and dry and crush it at 60-80 ℃ for 2-8 hours to obtain the finished low molecular weight white sodium alginate product. Wet oligomeric sodium alginate [60-80℃, 2-8h] → Sodium oligomeric alginate finished product.
-
Method of production -2：
Method of manufacturing seaweed (mixed with 1/3 seaweed) as raw material
- Pinch, fix, digest and precipitate algae algae (mixed with 1/3 seaweed), remove sediment and other substances, pinch in clean water for two hours, wash thoroughly and add a 0.8% formaldehyde solution that is 10 times the dry weight of the raw material to pinch and fix for at least 16 hours (shorter in summer and longer in winter). Take 10-15 times the dry weight of the raw materials, take 10-15 g/L (1%-1.5%) sodium carbonate, heat it to about 80 ℃, add the raw materials, keep it at 50-60 ℃, stir and digest at 60r/min for 3-4 hours, dilute the digestion solution with 60-70 times the dry weight of the raw materials in water, measure the viscosity of the solution as 110Pa·s using an Engler viscometer, and precipitate for 8 hours. Release the supernatant, filter through 80-100 mesh silk, filter the lower layer of precipitation and pressure filtration, remove the slag and precipitate the filtered gel solution for another 4-8 hours. Combine the filtrate to obtain the supernatant;
- Kelp (mixed with 1/3 seaweed) [water, HCHO] → [room temperature 18h] solid [Na2CO3, water] → [50-60℃, 3-4h] paste [water] → [8h] supernatant;
- Acid coagulation, neutralization and drying: Take the clarified gel solution and filter into the acid polymerization tank while adding hydrochloric acid. The gel tube and the acid tube are double tubes collided together, and the acid coagulation is fast, not exceeding half an hour. The pH is controlled to 1-1.5. After acid coagulation, rinse the alginate with water, wash the solution at pH 1.5-2, bag it, self-filter for a while, press the filter and get the alginate with a water content of 85% -90%. Then mix the alginate in pieces, add an appropriate amount of pure alkali to neutralize it in a sodium alginate suspension, and wait no more than 8 hours. After neutralization, spread it over a glass plate and dry it directly at 70-80 ℃, not exceeding 90 ℃. Crush it to obtain raw sodium alginate. Above [HCl] → [pH 1-1.5] Alginate [water] → [pH 1.5-2] Alginate [Na2CO3] → [pH 7-8, 8h] Seaweed sodium concentrate → [70-80℃] crude product;
- Bleach and degrade 280L of soft water, heat to 60-70℃, stir evenly and spray 10kg of sodium alginate. Continue heating and stirring until completely dissolved, then add an appropriate amount of sodium hypochlorite solution evenly and stir thoroughly. During the reaction process, the viscosity of the gel gradually decreases, and the color of the reaction solution becomes lighter. After qualifying the viscosity, 2 kg of activated carbon are immediately added, stirred for 20 minutes, discolored and filtered while heating to obtain a transparent filtrate;
- Raw product [water, Na2CO3, activated carbon] → [60-70℃] Transparent filter (oligosodium alginate)
- The precipitation and drying of the filtrate is carried out in a sedimentation tank filled with 80% ethanol. Ethanol: filtrate=2:1 (volume ratio) is used for precipitation. 1 kg of activated carbon is added for decoloration and pressure filtration. Centrifuge and rotate the precipitate obtained in ethanol, remove the fibrous material and crush it, soak it in 90%-95% ethanol, completely dehydrate it, rotate again, check for foreign objects on the surface, if any, scrape the surface and then make particles. Dry below 65°C to obtain the low molecular weight sodium alginate finished product. The relative molecular weight is 20000-31000;
- Low molecular weight sodium alginate [ethanol] → low molecular weight sodium alginate finished product [below 65 ℃];
- Take 4 g of low molecular weight sodium alginate, 50 g of glucose, 3 g of sodium chloride, 0.015 g of citric acid, 0.113 g of disodium hydrogen phosphate (Na2HPO4·12H2O), and add water for injection to 1000ml. Take 1/2 of the total amount of water for injection, slowly add sodium alginate while stirring, heat adequately until completely dissolved, then add sodium chloride, citric acid and disodium hydrogen phosphate and stir until completely dissolved. Dissolve the glucose in a quantitative amount of water, mix it with the above solution and then add water to the full amount. Add 1-3 g/L (0.1%-0.3%) activated carbon according to the total amount of the drug solution, boil for 20-30 minutes, filter with 4-10 layers of filter paper using a Buchner funnel to obtain a colorless and transparent liquid (relative viscosity 2.4-3, pH 5-7), filter with a vertical melting funnel No. 3, divide and sterilize at a pressure of 49 kPa (0.5 kgf/cm2) and 110-112°C for 50 minutes to obtain a colorless or nearly colorless sodium alginate injection solution;
- Low molecular weight sodium alginate finished product → Low molecular weight sodium alginate injection.
Section 4： Market Outlook of Sodium Alginate
- The market outlook shows a steady growth trend, is expected to maintain a compound annual growth rate of about 12% in the next five years, and the market size is expected to exceed 15 billion yuan in 2030.
- Technological progress: bioengineering, nanotechnology and other applications to enhance product performance, intelligent production equipment to reduce production costs.
- Policy support: environmental regulations promote the promotion of green production technology, food safety policies to strengthen quality control.
- Demand growth: aging population and rising health awareness drive demand for food, healthcare products and cosmetics.