What is caustic soda flakes?

Technical sodium hydroxide flakes obtained by evaporating liquid caustic soda are also called caustic soda. It is used in chemical synthesis methods, processing of oil products, textile manufacturing in silk production and in bleaching fabrics, paper industry, soap production, aluminium and metal production.

Caustic soda, also known as sodium hydroxide, is an inorganic alkali salt which is hygroscopic in nature and is soluble in both water and a polar solvent. It is mainly used in textiles in the form of caustic soda flakes or pearls. It has a slippery feel and absorbs carbon dioxide in the atmosphere to form sodium carbonate. The chemical formula for caustic soda flakes is NaOH.

Being a basic compound, it undergoes a neutralization reaction with acid and forms the corresponding salt and water. It will also corrode metals such as aluminium, producing hydrogen gas which behaves as an explosive gas. Caustic soda has a decomposing effect on proteins and may penetrate deep tissues, hence caution must be exercised when handling.

Manufacturing Process

There are few methods of the manufacturing process or how to make caustic flakes, which by metathesis reaction and chloralkali process.

Metathesis Reaction

By reacting sodium carbonate with calcium hydroxide, sodium hydroxide, and calcium carbonate is produced. These products can be easily separated by filtration as calcium carbonate is not soluble whereas sodium hydroxide is highly soluble. The solution will then be purified, processed, and standardized for industrial consumption.

Chloralkali Process

With the electrolysis of sodium chloride solution, solid sodium hydroxide is manufactured and obtained with the evaporation of water. Chlorine gas is also produced as the main by-product. This is done through three main types of cells, mainly mercury cell, diaphragm cell, and the membrane cell.