Purification of chlorine

Table II. Composition of Products during the Purification of Chlorinated Dibenzo-/ -dioxin...

Fig. 8.16 Photocatalytic purification of chlorinated hydrocarbons in groundwater TCE is dispersed into the airstream, which is treated with photocatalyst.

The preparation and purification of chlorine were described on page 103 together with methods for other halogens. 

S. Sarangapani, D. Gage, and T.V. Bommaraju, Electrochemical Purification of Chlorine from Chlor-Alkali Tail Gas, 2002 NSF Design Service and Manufacturing Grantees and Research Cortference, San Juan, PR (2002). 

De Rivas B, Ldpez-Fonseca R, Sampedro C, Gutierrez-Ortiz 11. Catalytic Behaviour of Thermally Aged Ce/Zr Mixed Oxides for the Purification of Chlorinated VOC-containing Gas Streams. Appl Catal B Environ 2009 90 545-555. 

Hagg, M.-B. (2001). Purification of chlorine gas with membranes— An integrated process solution for magnesium production. Sep. Purif. Technol. 21, 261. 

Purification of drinking water by adding CI2 to kill bacteria is a source of electrophilic chlorine and contributes a nonenzymatic pathway for a chlorina tion and subsequent chloroform formation Al though some of the odor associated with tap water may be due to chloroform more of it probably results from chlorination of algae produced organic com pounds... 

Chlorine. The solubiUty of chlorine [7782-50-5] in hydrochloric acid is an important factor in the purification of by-product hydrochloric acid. The concentration of chlorine in solution, S, is proportional to the partial pressure of chlorine, p, in the gas phase and follows Henry s law, S = i/p, in the... 

An integrated process for producing chlorine dioxide that can consume chlorine (46) involves the use of hydrochloric acid as the reductant. The spent chlorine dioxide generator Hquor is used as feed for chlorate production, and hydrogen gas from chlorate production is burned with chlorine to produce hydrochloric acid. The principal disadvantage in the integrated hydrochloric acid-based processes is that the chlorine dioxide gas contains Y2 mole of chlorine for each mole of chlorine dioxide produced. A partial purification is achieved by absorption in chilled water in which the solubiHty of chlorine is less than chlorine dioxide however, this product stiU contains 10—15% chlorine on the basis of total chlorine and chlorine dioxide. 

The present method offers several advantages over earlier methods. The use of carbon tetrachloride instead of diethyl ether as solvent avoids the intrusion of certain radical-chain reactions with solvent which are observed with bromine and to a lesser degree with chlorine. In addition, the potassium bromide has a reduced solubility in carbon tetrachloride compared to diethyl ether, thus providing additional driving force for the reaction and ease of purification of product. The selection of bro-... 

The flask should be full of chlorine gas when the tare weight is taken. The success of this preparation depends in large measure on the use of stoichiometric quantities of all reagents. An excess or dehdency of any one will lead to an impure product and will greatly complicate the problem of purification. ... 

Other industrial applications of electrolysis include extraction/purification of metals from ores, electroplating, and the manufacture of certain chemicals such as sodium hydroxide. In the latter, sodium chloride solution when electrolysed is converted to sodium hydroxide to produce chlorine at the anode and hydrogen at the cathode. Both of these gaseous by-products are collected for industrial use chlorine is used in the production of bleach and PVC hydrogen is used as a fuel, to saturate fats, and to make ammonia. 

The products of this electrolysis have a variety of uses. Chlorine is used to purify drinking water large quantities of it are consumed in making plastics such as polyvinyl chloride (PVC). Hydrogen, prepared in this and many other industrial processes, is used chiefly in the synthesis of ammonia (Chapter 12). Sodium hydroxide (lye), obtained on evaporation of the electrolyte, is used in processing pulp and paper, in the purification of aluminum ore, in the manufacture of glass and textiles, and for many other purposes. 

Silicon reacts directly with chlorine to form silicon tetrachloride, SiCl4 (this reaction was introduced in Section 14.17, as one step in the purification of silicon). This compound differs strikingly from CC14 in that it reacts readily with water as a Lewis acid, accepting a lone pair of electrons from H20 ... 

Catalytic incineration has been appHed in the abatement of chlorinated VOC emissions in the pharmaceutical industry. The major compounds in the emission mixture are dichloromethane, perchloroethylene, dimethylformamide, oxitol, and toluene. The incinerator operates normally at 400-500 °C, but when emissions contain perchloroethylene the temperature is increased up to 500-600 °C. The emission mixture also contains water, which pushes the selectivity further toward HCl formation instead of formation of CI2. After oxidation, the product gases are washed with NaOH scrubbers. The purification level of over 99% can be achieved with the incinerator, the activity of which has been shown to be very stable after one year of continuous operation [69-71]. 

On this basis a demonstration plant having a capacity of 10 000 tonnes a-1 of chlorine was built in the Bayer production plant at Leverkusen. The plant was successfully commissioned on 4 January 2000. Figure 4.8 illustrates the electrolyser section of the plant, with the peripheral apparatus arranged mostly outside this building. The 76-element electrolyser was found to behave very smoothly and could be immediately operated up to 5 kA m-2 without any problems. Permanent operation is performed at 4 kA m-2. The power consumption was found to be about 1080 kWh tonne-1 CI2 with a typical current efficiency of nearly 100%. Chlorine purity is found to be 99.9%, which obviates the need for a chlorine liquefaction purification and therefore simplifies the plant drastically. 

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