Basic Information

Citric Acid is an important organic acid, also known as citric acid, colorless crystal, often containing one molecule of water of crystallization, odorless, strong acidity, and soluble in water. Its calcium salt is easily dissolved in cold water than hot water, and this property is commonly used to identify and separate citric acid. Anhydrous citric acid can be obtained by controlling a suitable temperature during crystallization. There are many uses in the industrial, food, and cosmetic industries.

Citric acid is also known as sulphuric acid, the chemical name 2-hydroxypropane-1,2,3-tricarboxylic acid. According to its water content, it is divided into monohydrate citric acid and anhydrous citric acid. Citric acid is widely used in the food industry for more than 75% of production. It can be used as a sour agent for foods, as an antioxidant, as a pH adjuster for foods such as refreshing drinks, jams, fruits and pastries. It is used in the pharmaceutical industry for about 10%, and is mainly used as an anticoagulant, an antacid, a flavoring agent, and cosmetics. It is used in the chemical industry, etc., and is used as a buffer, a complexing agent, a metal cleaning agent, a mordant, a gelling agent, a toner, and the like. It is very broad in the industrial fields of electronics, textiles, petroleum, leather, construction, photography, plastics, foundry and ceramics.

Physical and chemical properties

At room temperature, citric acid is a colorless translucent crystal or white granule or white crystalline powder, which is odorless, extremely odorous, and slightly deliquescent in moist air. It may be in the form of an anhydrate or a monohydrate: when citric acid crystallizes from hot water, it forms an anhydrate; when crystallized in cold water, it forms a monohydrate. Upon heating to 78 ° C, the monohydrate will decompose to give an anhydrate. At 15 degrees Celsius, citric acid can also be dissolved in absolute ethanol. The crystal form of citric acid varies with crystallization conditions. There are anhydrous citric acid C6H8O7 and citric acid containing 2C6H8O7.H2O, C6H8O7.H2O or C6H8O7.2H2O.

Structurally citric acid is a tricarboxylic acid compound and thus has similar physical and chemical properties to other carboxylic acids. When heated to 175 ° C, it decomposes to produce carbon dioxide and water, leaving some white crystals. Citric acid is a strong organic acid, and 3 H+ can be ionized; heating can be decomposed into various products and react with acids, bases, glycerol and the like.