What is Caustic Prills

Caustic soda is mainly used in textile in the form of caustic soda flakes or prills. It is also known as sodium hydroxide, has a white solid appearance and a formula of NaOH. It is an inorganic alkali salt, hygroscopic in nature and is soluble in water and polar solvents. It has a slippery feel and also absorbs carbon dioxide in the atmosphere to from sodium carbonate. Being a base, it will undergo neutralization reaction with acid and form relevant salt and water. It will also corrode metals such as aluminum, generating hydrogen gas that has potential to behave as an explosive gas. Caustic soda also has decomposing effects on proteins and may penetrate deep tissues.

Manufacturing Process

Castner-Kellener process – Here, caustic soda is prepared by the electrolysis of aqueous NaCl. It consist mercury cathode cell which is a rectangular vessel divided into three compartments by a non-porous slate partition which do not touch the bottom of the cell. A layer of mercury divides each compartments at the bottom of the cell. One end of the cell is pivoted and the rest of the part rests on an in centric wheel, which gives the rocking motion to the cell so mercury can circulate from one compartment to other. Castner-Kellener cell – It is a rectangular cell made up of steel. The inner walls of the tank is lined wih ‘ebonite’. Anode is titanium and mercury acts as cathode. Ionization of NaCl – When the solution is subjected to electric discharge the NaCl disassociates into Na+&Cl- ions, now the positive and negative charges migrates towards its respective electrodes. The sodium deposited at mercury forms sodium amalgam and the chlorine produces at the anode is removed from the top of the cell.

Reaction at cathod – 2Na++2e-→2Na  |  Na+Hg→Na/Hg           Reaction at anode – 2Cl-Cl2+2e-

Caustic Prills Applications

Caustic Prills is used in pulp and paper, textiles, metallurgy, soap and detergents. Basically, this product will go through the neutralization reaction with the acid, and form the relevant salt and water. It will also corrode metals such as aluminum, producing hydrogen gas which is a potentially explosive gas. Besides, there is still much more about the use of this refined glycerine.

Pulp and Paper

It is used in the pulp and paper industry during the cooking process and oxygen delignification process.


It is employed in the textile industry during the scouring process, mercerization process, and dyeing


Soap and Detergents 

It is applied during the saponification process in soap industries and neutralization process in detergent



It is used to extract alumina from bauxite ore via the Bayer process.


Origin China