Chlorine industrial uses

Unfortunately, the production of a single cell cannot be measured with sufficient accuracy to give meaningful results. To get around this problem, the chlorine industry uses an equation based on the analysis of the chlorine gas, the cell liquor, and the anolyte ... 

Most of the byproduct HCl is used captively, primarily in oxyhydrochlorination processes for making vinyl chloride and chlorinated solvents or for Mg processing (p, 110), The scale of the industry is enormous for example, 5,2 million tonnes of HCl per annum in the US alone (1993), HCl gas for industrial use can be transmitted without difficult over moderate distances in mild-steel piping or in tank cars or trailers. It is also available in cylinders of varying size down to laboratory scale lecture bottles containing 225 g. Aqueous hydrochloric acid consumption (1993) was 1,57 Mt (100% basis). Price for anhydrous HCl is 330/tonne and for 31,4% aqueous acid 73/tonne (1993) depending on plant location and amount required. 

The returns for the industry can be monitored (see Figs 1.1-1.3). The selling price of caustic soda is fairly transparent everywhere and chlorine pricing is transparent in the USA. Chlorine is less transparent outside the USA as most of the consumption is captive rather than merchant. The market for ethylene dichloride (EDC) is, however, transparent and chlorine values can be worked out from the selling price of the EDC and the input price for the ethylene. Knowledge of the chlorine value and the caustic value gives the value of the Electrochemical Unit or ECU. This provides a measure of the profitability of the business at any time. Convenient marker prices can be found in the US Gulf for both EDC and caustic as well as out of north-west Europe. 

Meanwhile, many other chemicals have enabled our society to accomplish great technical advances. For example, we have learned to recover fossil hydrocarbons from the earth and use these for heating, for transportation fuels, and for synthetic starting materials. Likewise, synthetic compounds like tetraethyllead, chlorinated solvents, freons, methyl /-butyl ether (MTBE), polychlorinated biphenyls (PCBs), and many others (see Chapter 2) have enabled us to develop products and perform industrial processes with greater efficiencies and safety. However, it has become quite apparent that even such contained applications always result in a certain level of discharge of these compounds to the environment. 

Chlorinated phenols are among the most important contaminants in the environment (aqueous systems and soils) due to their widespread use in industry and agriculture and for domestic purposes for over 50 years. It is well-known that chlorophenols are toxic at low levels. The more highly chlorinated phenols such as trichlorophenols and pentachlorophenol are also persistent. Five of the chlorophenols (2-chlorophenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol and pentachlorophenol) have been classified as priority pollutants by the US Environmental Protection Agency (EPA). 

US Environmental Protection Agency (1989) Office of Water Regulations and Standards, Industrial Technology Division. Method 1613 Tetra-through octa-chlorinated dioxins and furans by isotope dilution HRGC/HRMS... 

It is now very well estabhshed that DOM is the major source of trihalomethanes and other disinfection by-products in disinfected water. In fact, the measurement of THMFP is now a routine monitoring task in the water treatment industry, and suppliers in the US are required to advise consumers of the concentrations of trihalomethanes and other disinfection by-products in drinking water. Efforts to remove DOM from waters before they are chlorinated have driven much of the research that has led to advances in membrane-based methods of isolation of DOM from water (see the discussion of UF, NF, etc., in Section 5.10.4.2.2). Nikolaou and Lekkas (2001) have recently reviewed many aspects of the reactions of DOM with chlorine and other disinfectants. They review the relationships between reactivity of DOM (i.e., formation of disinfection by-products) and the chemical properties of DOM and several types of fractions of DOM. They also discuss the formation and potentially adverse effects of several classes of disinfection by-products. Urbansky and Magnuson (2002) have reviewed the subject of disinfection by-products, including a brief discussion of DOM. Both of these reviews are recommended for further up-to-date details on the role of DOM in the formation of disinfection by-products. 

Approximately 50% of US drinking water supplies are drawn from groundwater, and of these about 25% have been detected with VOCs above the Maximum Contaminant Level [73], Sources of contamination include agriculture and industry, hazardous waste disposal, underground storage tanks, and accidental spills. The organic contaminants of particular concern are chlorinated aliphatic and aro-... 

Phenols of enviromnental interest are derived from a wide variety of industrial sources, or present as biodegradation products of humic substances, tannins, and lignins, and as degradation products of many chlorinated phenoxyacid herbicides and organophosphorous pesticides. Phenols, especially chlorophenols, are persistent, and toxic at a few pg/1. Therefore, phenols are hsted at the US-EPA hst of priority pollutants and the EU Directive 76/464/EEC as dangerous substances. The samples to be analysed can be surface waters or industrial effluents. 

The basic structure of the German Edition has been retained. Changes in the industrial importance of some compounds and processes since the appearance of the German edition have been taken into account and data relating to the US market have been emphasised. Thus the chapter on potassium permanganate has been considerably abridged and that on the membrane process for the manufacture of chlorine and sodium hydroxide expanded. 

When Molina and Rowland made their prediction in 1974, world production of CFCI3 and CF2CI2 was approximately 0.3 and 0.5 Mton respectively fluorocarbon production in the US was growing by 8.7% per year around 1970 [27]. Six years later, and every year since then, the predicted ozone hole was detected over Antarctica, when the chlorine concentration in the same atmospheric layer was approximately 2000 pmol mol [29]. After this dear evidence of the deleterious effects of CFC, in 1987 this class of substance and most bromofluorocarbons were banned from further industrial use in the Montreal Protocol (ratified by the first 29 states in 1989). Because of the decade-long lifetime of stratospheric CFC, their phasing-out can be expected to show an effect no earlier than approximately 2040. 

According to a conservative estimate of the research activities of the US pharmaceutical industry alone, several millions of new compounds are synthesized every year, approximately 50,000 of which are highly toxic. In the search for medical cures these toxic compounds are of little utility. However, they have one of the key requirements, toxicity, of any potential chemical warfare agent. This does not automatically make them a suitable candidate for this purpose, but since the information on these compounds remains with the companies that first synthesized them, this might provide a very useful resource to tap into in any search for new chemical warfare agents.38 If the utilization of chlorine and phosgene during World War I... 

The family of hazardous pollutants also includes phenol and its nitro and chloro derivatives. They enter the aquatic environment through waste-waters from many industries, such as petroleum processing and production of plastics, dyes, cellulose, pharmaceuticals, etc., or as the products of pesticides decomposition. Phenols may also arise in drinking water from the reaction of natural humic and fulvic acids with chlorinating disinfectants. Even at non-toxic levels, they deteriorate the taste and odor of drinking water. To address the steady increase in water contamination with phenolic compounds and pesticides, the US Environmental Protection Agency (EPA) has included 26 phenoHc compounds and 32 pesticides and their metaboHtes in the list of priority contaminants. In accordance with regulatory requirements, the allowed tolerance hmit of these pollutants must not exceed O.lpg/L for individual species and 0.5 Xg/L... 

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