How green is caustic soda?

~ Greencard for: caustic soda ~
	Weight:	1	Kg
	Lifespan:	0.25	Years
	Enegy to make:	0.73	Kwh
	Energy use:	N/A	Kwh per year
	Co2 footprint	0.8	Kg
	Chemical footprint:		Medium
	Waste footprint:	18	%
	Carbon offset:	0.24	Trees

In 1998, total world production was around 45 million tonnes. North America and Asia collectively contributed around 14 million tonnes, while Europe produced around 10 million tonnes.

What goes into caustic soda

Caustic soda (Sodium hydroxide) is produced (along with chlorine and hydrogen) via the chloralkali process. This involves the electrolysis of an aqueous solution of sodium chloride. The sodium hydroxide builds up at the cathode, where water is reduced to hydrogen gas and hydroxide ion. Uses: Bleach – used to make bleach for mold and mildew control around the home or to control microbial levels in swimming pools,cleaners for beverage bottles,drain and pipe cleaners and other household cleaning products. Petroleum products – used to explore, produce and process petroleum and natural gas. Aluminum production – used to dissolve bauxite ore, the raw material for aluminum production. Chemical processing – used as a basic feedstock for a wide range of products, including solvents, plastics, fabrics, adhesives, herbicides, dyes, inks, pharmaceuticals.

Chemical contamination

Caustic soda is a strong corrosive substance and can cause severe burns. Contact with water causes a chemical reaction producing heat, steam and noxious fumes. In some manufacturing proccesses mercury is used and has to be removed from waste streams. Chlorine gas is also produced as a by product. There is no evidence that caustic is a skin sensitizer or is readily absorbed through the skin. It is not a known carcinogen, developmental toxicant or reproductive toxicant. Release of caustic soda into the environment can result in an increased PH, small spills can be neutralised with acetic acid (vinegar)

Lifetime embodied energy

Caustic soda is manufactured by electrolysis using naturally-occurring salt (in the form of brine) to produce two basic products: caustic soda and elemental chlorine, hydrogen is produced as a by product. The sodium chloride brine is electrolysed to produce chlorine at the positive electrode (anode) and sodium hydroxide and hydrogen at the negative electrode (cathode).

Recycling and material recovery

Caustic soda as a rule can't be recycled; disposal is by dilution or neutralisation by an acid solution, acetic acid for example (vinegar).

Factoids [1]

Caustic Soda is commonly used in food production in Germany, where dough is coated in it before being baked.

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