Citric acid is a weak organic acid which has the appearance of colourless, odourless crystals with a strong acid taste. The chemical is denser than water. It exists in two forms, anhydrous and monohydrate forms.
1. The anhydrous form- this form has no water of crystallization and is also known as the water-free form of citric acid.
2. Monohydrate form- this form has a water molecule that is associated with one citric acid molecule. It is formed when citric acid is crystallized from cold water. It can be converted to the anhydrous form at about 780C.
Some of the industrial and consumer applications of citric acid include:
i. Use as an adhesive and sealant in chemicals.
ii. Use as a corrosive inhibitor and anti-sealing agents.
iii. Use as a dye. Here it acts as an alternative to white vinegar for home dyeing as it is odourless.
iv. Use as an oxidizing and reducing agent.
v. Use as a plating and surface treating agent.
vi. Use as a refractory.
vii. Use as a solid separation agent.
viii. Use as a solvent for cleaning and degreasing.
ix. Use as a viscosity agent.
x. For pH adjustment. It is used as an acid to adjust pH, and as a dispersing agent to stabilize emulsions and other multiphase systems. It also has a pleasant, clean, and tart taste which makes it useful in food and beverage products.
xi. It is an active ingredient in products registered for residential and commercial use as sanitizers, disinfectants, sanitizers, and fungicides.
xii. It is used to prevent the clotting of blood intended for transfusion by acting as an anticoagulant, generally in solutions with glucose.
xiii. It used in the cosmetic industry to make beauty products by mixing it with sodium bicarbonate to make bath tablets and bath fizzes. It is also applied in lotions and skin masks.
xiv. It is used to supply fertilizer micronutrients.
xv. In hair care, it is used in small quantities together with shampoo to wash colouring agents from hair.
xvi. It is also used in ink, toner and colourant products.