Caustic soda also known as sodium hydroxide and NaOH is the natural co- product of chlorine production. Firstly it was introduced by Nicolas Leblanc, a French chemist. It is a widely used chemical in industrial processes and constituents an essential reactant in the production of many useful organic chemicals. In addition it is used in a wide range of applications part of our daily lives. Act as a strong base soluble in water, although caustic soda is slightly toxic to aquatic organisms, a large amount of discharge can change the pH of the aquatic system which may be toxic to aquatic organism.
Being as a highly corrosive and reactive chemical, it can be irritating to the eyes, skin and gastrointestinal tract. It is one of the oldest man- made chemicals with excavations in Egypt presenting samples of it dating from 3000 B.C. The chemical is created with world production standing at approximately 60 million ton per annum (according to statistics in 2008). Most of the manufacturers of this chemical uses chloralkali process in which natural occurring salt produce two major products i.e. caustic soda and elemental chlorine with hydrogen. Process includes the electrolysis of sodium chloride using one of three types of cells such as membrane, diaphragm and mercury.
Generally the caustic soda sold in liquid form which is odorless and colorless liquid. However some impurities can be found in caustic soda such as sodium carbonate, sodium sulfate and sodium chloride. Having excellent chemical and physical properties, chemical is used in wide range of applications. The paper, pulp and cellulose industries are the major users of caustic soda worldwide. Other areas where this chemical is used are food and water treatment industry. The textile sector, soaps, detergents and mineral oil industries also use caustic soda for different purposes.
About 4% of the production is used in the process of refining aluminum from its ore bauxite and the remaining has miscellaneous applications like in recycling of rubber and acids neutralization process. It used as a basic feedstock for a wide range of downstream products such as adhesives, herbicides, dyes, inks, plastics, fabrics and pharmaceuticals etc. It removes objectionable smells from petroleum materials and natural gas that arise from the presence of hydrogen sulfide (H2S). Bleach manufacturing industry use sodium hydroxide to make bleach which has both consumer and industrial applications.
Although chemical has wide range of industrial and domestic applications, it has large exposure potential. Being as a highly corrosive chemical in industry, precautions should be taken to minimize the potential harm to human being, animals and the environment. Manufacturers should follow some guidelines in order to prevent the waste release from the chemicals. If sodium hydroxide does reach water and soil nearby, it can increase the pH value of the terrestrial as well as aquatic environment. In case of large spills from the industries, the material is collected, re processed and disposed off according to the applicable requirement. It is advisable to follow emergency procedure and safety measures while dealing with caustic soda.
