1. An industrial manufacturing unit produces chlorine using the chloralkali proc
ID: 286413 • Letter: 1
Question
1. An industrial manufacturing unit produces chlorine using the chloralkali process.
Using the link provided here on the details of chloralkali process answer the following
(10) https://en.wikipedia.org/wiki/Chloralkali_process
a. Is it an example of join production or co-production? (2)
b. Suppose, chlorine is the determining product for the industrial manufacturing unit. How would you utilize system expansion for allocation of life cycle impacts to production of chlorine. [Hint: Identify the intermediate and displaced processes. Clearly write the information used for selecting the intermediate processes and the displaced processes along with how you are allocating the impact to determining product chlorine] (5)
c. What is the determining product for the intermediate process ? Write explanation for choosing the intermediate process. (3)
Explanation / Answer
a). Yes it is the example of co-production. It is the technology used to produce chlorine and sodium hydroxide which are commodity chemicals required by industry. 35 million tons of chlorine were prepared by this process in 1987.Industrial scale production began in 1892.
Primary chlorine is almost entirely produced by electrolysis of sodium chloride salt (brine), with sodium hydroxide (caustic soda) as a co-product.
b).Chlor-Alkali Process
More than 95 percent of the domestic chlorine produced results from the chlor-alkali process that involves the electrolysis of brine (Chemical Week,1996). Chlorine and sodium hydroxide are co-products of electrolysis of sodium chloridebrine. Electricity acts as acatalyst in this reaction, whichtakes place in electrolytic cells. The amountof electricity required depends on electrolyticcell parameters such as current density, voltage, anode and cathode material, and the cell design.
Life cycle impacts on production of chlorine :
There are environmental/health arguments against the use of chlorine for bleaching paperpulp, and against the dissipative use of chlorinated pesticides, chloro-carbon solvents and chloro-fluorocarbons. Because of these problems the industrial use of chlorine itself is being challenged, especially by the environmental organization Greenpeace [Thornton 1991, 1993]. However, strong support for reducing the use of chlorine has also come from the International(US-Canadian) Joint Commission. In its Sixth Biennial Report, the Joint Commission recommended that "the use of chlorine and its compounds should be avoided in the manufacturing process".
The chlorine industry, feeling threatened, is mounting an active defense [Amato 1993]. Through its industry associations, it has also funded a monumental study of the toxic effects of chlorine chemicals, by a panel of independent toxicologists. This study concluded that "the alarms about chlorine containing compounds are unwarranted" and that "the mere presence of chlorine in a molecule does not necessarily confer unique toxic properties or bioaccumulative potential". However, the panels conclusions are admittedly based, to a large extent, on the low exposure probabilities and low concentrations of toxic or carcinogenic chlorinated compounds in most environments, rather than on the intrinsic harmlessness of the chemicals.
c). Chlorine and sodium hydroxide are co-products of electrolysis of sodium chloridebrine.The intermediate method of chlorine production is easy to processing, it prone to safety of health regarding human health. Thus method is various used by many industialists to chlorine production in comercial level.
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