Other Free Encyclopedias » Science Encyclopedia » Science & Philosophy: Dysprosium to Electrophoresis - Electrophoretic Theory » Electrolysis - Electrolysis Of Water, Production Of Sodium And Chlorine, Production Of Magnesium, Production Of Sodium Hydroxide, Chlorine And Hydrogen

Electrolysis - Production Of Sodium Hydroxide, Chlorine And Hydrogen

water salt ions electrons

Sodium hydroxide, NaOH, also known as lye and caustic soda, is one of the most important of all industrial chemicals. It is produced at the rate of 25 billion pounds a year in the United States alone. The major method for producing it is the electrolysis of brine or "salt water," a solution of common salt, sodium chloride in water. Chlorine and hydrogen gases are produced as valuable byproducts.

When an electric current is passed through salt water, the negative chloride ions, Cl-, migrate to the positive anode and lose their electrons to become chlorine gas.

(The chlorine atoms then pair up to form Cl2molecules.) Meanwhile, sodium ions, Na+, are drawn to the negative cathode. But they do not pick up electrons to become sodium metal atoms as they do in molten salt, because in a water solution the water molecules themselves pick up electrons more easily than sodium ions do. What happens at the cathode, then, is

The hydroxide ions, together with the sodium ions that are already in the solution, constitute sodium hydroxide, which can be recovered by evaporation.

This so-called chloralkali process is the basis of an industry that has existed for well over a hundred years. By electricity, it converts cheap salt into valuable chlorine, hydrogen and sodium hydroxide. Among other uses, the chlorine is used in the purification of water, the hydrogen is used in the hydrogenation of oils, and the lye is used in making soap and paper.

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about 5 years ago

without special mambrane you cannot make sodium hydroxide from brine.
you make only "eau de javel" (NaOCL) (bleach) with simple brine electrolysis.
talk right or shut up.

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over 4 years ago

I am a new intrepreneur. I would like to set up a small scale sodium hydroxide production plant.How and who can help me to set up a ion exchange membrane cell. Or how can I buy a complite IEM cell for production of sodium hydroxide.


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over 1 year ago

i want the industries names

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about 1 month ago

i lean a lot, thanks keep up dates me

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9 months ago


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10 months ago

I want to manufacturing NaOH from iodized NaCl salt. how can I produce NaOH from iodized NaCl salt and what are the two electrodes for electrolysis of iodized NaCl salt.

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10 months ago

Hi just want to know whether or not the production of Nacl can be proceed in small scale experiments and what is Nacl molarity needed. Many thanks

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10 months ago

this is good knowledge

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12 months ago

I want to know, can you suggest a small-sized the machine produces Lye? This is because I want to do a trial.
Thank you

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almost 2 years ago

its best to use carbon rods that you can get from zinc-carbon batteries.

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over 2 years ago

dear sir

I want to make waterjavel,I am using 2 stainless steel electrod but I havent been sucsesful please help to do the job?