Citric acid is an important organic acid, also known as citric acid. It is colorless crystal, often contains crystal water molecules, is odorless, has a strong sour taste, and is soluble in water. Its calcium salt is more soluble in cold water than in hot water, which is usually used to identify and separate citric acid. Anhydrous citric acid can be obtained by controlling the appropriate temperature during the crystallization process. It has many uses in industry, food industry and cosmetics industry.
Sodium citrate, also known as sodium citrate, is an organic compound with the appearance of white to colorless crystals. Tasteless, cool, salty and spicy. It is stable in normal temperature and air, slightly soluble in humid air, and weathered in hot air. When heated to 150°C, crystal water will be lost. Easily soluble in organic solvents such as water, glycerin and alcohol. It decomposes at high temperature, deliquesces in humid environment, and weathers in hot air. The pH of the solution is about 8.
Sodium citrate is used as an acidity regulator, flavor and stabilizer in the food and beverage industry; as an anticoagulant, expectorant and diuretic in the pharmaceutical industry; in the detergent industry, it can replace sodium tripolyphosphate as Non-toxic detergent additive; it is also used in brewing, injection, photographic medicine and electroplating.
1. Different chemical formulas
Citric acid: C6H8O7, sodium citrate: na3c6h5o7·2H2O.
2. The taste is different
Citric acid: It has a strong sour taste. Sodium citrate: It has a cool, salty and spicy taste.
3. Different uses
It can be used as a food acid, antioxidant, and pH regulator for cold drinks, jams, fruits and cakes. About 10% of them are used in the pharmaceutical industry, mainly used as antacids, condiments, cosmetics, etc.
About 15% of them are used in the chemical industry, such as buffers, complexing agents, metal cleaning agents, mordants, gelling agents, toners, etc. It has very broad prospects in the fields of electronics, textiles, petroleum, leather, construction, photography, plastics, casting and ceramics.
Sodium citrate is used as an acidity regulator, flavor and stabilizer in the food and beverage industry; as an expectorant and diuretic in the pharmaceutical industry; in the detergent industry, it can replace sodium tripolyphosphate as a non-toxic detergent Additive; it is also used in brewing, injection, photographic medicine and electroplating.
4. Different raw materials
Natural citric acid is found in the fruits of plants, such as lemons, citrus, pineapples, and animal bones, muscles and blood. Synthetic citric acid is fermented from sugar, molasses, starch, grapes and other sugar-containing substances, and can be divided into anhydrous and hydrates. Pure citric acid is a colorless transparent crystal or white powder, tasteless, and has an attractive sour taste.
Citric acid + sodium hydroxide method
The earliest researched and developed production process is to dissolve citric acid in water, add it to sodium hydroxide solution, neutralize and generate a lot of heat, then filter, concentrate, crystallize, and dry to obtain the finished product.
Citric acid + soda ash method
The neutralization method improves the process. It is convenient to purchase soda ash as the raw material, has good preservation and low production cost;It is a production method widely used in industry.
Citric acid + sodium bicarbonate method
Dissolve high-quality sodium bicarbonate in water according to the calculated amount, neutralize with citric acid, concentrate and crystallize to prepare pharmaceutical grade sodium citrate. The reaction conditions are mild, the product quality is good, and the process operability is good. At present, this method is mainly used in some pharmaceutical factories.
Calcium citrate + soda ash method
double decomposition reaction of calcium citrate and soda ash, filter out insoluble matter, obtain sodium citrate