File Name: manufacture of chlorine and caustic soda .zip
Comprehensive Treatise of Electrochemistry pp Cite as. Chlorine and its coproduct, sodium hydroxide caustic soda , are significant factors in the world economy.
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Nearly all caustic soda is generated by the electrolysis of sodium chloride solution using one of three cell types: mercury, diaphragm and membrane cells.
The electrolysis process produces 2. The primary raw material is common salt, usually in the form of underground deposits which are brought to the surface as a solution in a pumped high pressure water supply.
The sodium chloride solution is often called brine. Traditionally, electrolysis has been carried out by the mercury amalgam or diaphragm cell processes but the ion exchange membrane cell is taking a growing share on environmental and economic grounds. The main production route in the US is via the diaphragm cell while the mercury and membrane cells are more dominant in Europe. There is environmental pressure on the older mercury route, with some bodies recommending a phase-out by In the mercury cell, sodium is discharged in the form of a mercury sodium amalgam and chloride ions as chlorine.
The amalgam flows to a totally separate compartment where it reacts with water to yield sodium hydroxide solution and hydrogen gas. The diaphragm cell, usually manufactured of asbestos, allows a flow of brine from the anode to cathode but separates the chlorine and hydrogen gas spaces. As hydrogen ions are discharged, hydroxide ions accumulate in the cathode compartment with the aqueous sodium ions to produce sodium hydroxide. Back migration of the hydroxide ions from the cathode to anode is prevented by the velocity of the liquid flow from one compartment to the other.
The chlorine formed at the anodes rises through the brine into a space formed by the cell's cover. In the membrane process, the ion exchange membrane acts as a barrier to all gas and liquid flows, and only allows the passage of sodium ions between compartments. The sodium ions pass in hydrated form to produce sodium hydroxide in the cathode where hydrogen is given off. Chlorine gas is liberated at the anode. The membrane is a copolymer of tetrafluoroethylene or a similar fluorinated monomer.
Mercury cells are cheaper to operate than diaphragm cells when electricity costs are low and produce product at the required concentration and high purity, but mercury must be removed from the effluent.
Diaphragm cells need plenty of thermal energy to concentrate the caustic solutions but can be cheaper than mercury cells when steam costs are low and have relatively cheap construction costs.
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Chlorine gas can be produced by extracting from natural materials, including the electrolysis of a sodium chloride solution brine and other ways. Chlorine can be manufactured by the electrolysis of a sodium chloride solution brine , which is known as the Chloralkali process. The production of chlorine results in the co-products caustic soda sodium hydroxide , NaOH and hydrogen gas H 2. These two products, as well as chlorine itself, are highly reactive. Chlorine can also be produced by the electrolysis of a solution of potassium chloride , in which case the co-products are hydrogen and caustic potash potassium hydroxide. There are three industrial methods for the extraction of chlorine by electrolysis of chloride solutions, all proceeding according to the following equations:. Mercury cell electrolysis, also known as the Castner—Kellner process , was the first method used at the end of the nineteenth century to produce chlorine on an industrial scale.
This information is notintended to be all-inclusive as to the manner and conditions of use, handling, storage, disposal and other factors that may involve other or additional legal,environmental, safety or performance considerations, and OxyChem assumes no liability whatsoever for the use of or reliance upon this information. Whileour technical personnel will be happy to respond to questions, safe handling and use of the product remains the responsibility of the customer. No sugges-tions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any Federal, State,local or foreign laws. It includes information on the manufacture,physical properties, safety considerations andanalytical methods for testing caustic soda. Caustic soda sodium hydroxideor NaOH is most commonly manu-factured by the electrolysis of asodium chloride NaCl solution.
Nearly all caustic soda is generated by the electrolysis of sodium chloride solution using one of three cell types: mercury, diaphragm and membrane cells. The electrolysis process produces 2. The primary raw material is common salt, usually in the form of underground deposits which are brought to the surface as a solution in a pumped high pressure water supply. The sodium chloride solution is often called brine.
The Alkali industry also known as chloralkali industry is a chemical technology industry in which chloralkali processes is carried out. The chloralkali process also chlor-alkali is an industrial process for the electrolysis of sodium chloride. It is the technology used to produce chlorine and sodium hydroxide caustic soda , which are commodity chemicals required by industry. To give some sense of scale, 35 million tons of chlorine were prepared by this process in Greenwood etal Industrial scale production began in
Пальцы Беккера схватили воздух, а дверь повернулась. Девушка с сумкой была уже на улице. - Меган! - завопил он, грохнувшись на пол. Острые раскаленные иглы впились в глазницы. Он уже ничего не видел и только чувствовал, как тошнотворный комок подкатил к горлу. Его крик эхом отозвался в черноте, застилавшей. Беккер не знал, сколько времени пролежал, пока над ним вновь не возникли лампы дневного света.
Similarly to the Membrane Cell, chloride ions are oxidized at the anode to produce chlorine, and at the cathode, water is split into caustic soda.