Citric acid, anhydrous, AR

White crystalline powder or granules, odorless. Easy to dissolve in water, easy to dissolve in alcohol, slightly soluble in chloroform, extremely slightly soluble in ether, insoluble in benzene. PH 1.7 (100g/L, H2O, 20 ℃). Melting point 152-159 ℃. Boiling point 200 ℃/760mmHg. Density ρ (20) 1.665g/mL. Viscosity 6.5mPa · s (25 ℃).

Citric acid has a strong chelating effect, which can chelate Fe3+and weaken its promoting effect on corrosion. It can remove metal oxide scales such as iron and copper, with simple and safe operation, and is suitable for various materials. Due to the absence of c1- in the molecule, it does not cause stress corrosion of equipment and is used as a cleaning agent. Citric acid has a lower corrosion rate on steel than hydrochloric acid. Citric acid is mainly used to remove rust and has poor solubility for calcium, magnesium, and silicon deposits, so it is mainly used for cleaning newly built large-scale facilities. Citric acid cannot remove calcium magnesium scale and silicate scale, but when mixed with aminosulfonic acid, hydroxyacetic acid, or formic acid, it can be used to clean rust and calcium magnesium scale. Citric acid mixed with EDTA can be used to clean heat exchangers. The corrosion inhibitor added to the citric acid cleaning solution is mainly thiourea, with a dosage of 0 1%, or 0.06% thiourea can be mixed with other corrosion inhibitors. In addition, it can also be used in the pharmaceutical field. Sodium citrate can prevent blood clotting, calcium salts can be used as stomach acid solubilizers, and barium salts are toxic.