Ozone-depleting compound

In this sequence the Cl also acts as a catalyst and two molecules are destroyed. It is estimated that before the Cl is finally removed from the atmosphere in 1—2 yr by precipitation, each Cl atom will have destroyed approximately 100,000 molecules (60). The estimated O -depletion potential of some common CFCs, hydrofluorocarbons, HFCs, and hydrochlorofluorocarbons, HCFCs, are presented in Table 10. The O -depletion potential is defined as the ratio of the emission rate of a compound required to produce a steady-state depletion of 1% to the amount of CFC-11 required to produce the 1% depletion. The halons, bromochlorofluorocarbons or bromofluorocarbons that are widely used in fire extinguishers, are also ozone-depleting compounds. Although halon emissions, and thus the atmospheric concentrations, are much lower than the most common CFCs, halons are of concern because they are from three to ten times more destmctive to O, than the CFCs. 

Does the Toller use a primary ozone depleting compound (ODC, for example, a CFC or 1,1,1, -trichloroethane) m their process Are ODC management practices followed (for example no uncontrolled releases of ODCs, installation of capture and recycle equipment, leak detection and repair, use of well trained personnel) ... 

Ozone depleting compounds (ODCs) (other than refrigerants) ... 

A separate set of processibility issues involves health, safety, and environmental concerns. Ozone-depleting compounds (ODCs), such as trichloroethane and... 

Arjun Makhuani, ANNtE Makhuani and A. Bickel, Saving our Skins Technical Potential and Policies for the Elimination of Ozone-Depleting Compounds, Environmental Policy Institute and Institute for Energy and Environmental Research, Washington, DC, 1988, 167 pp,... 

A very low ozone depleting compound that serves as a replacement for CFC-11 in centrifugal chillers. 

There is a need to verify whether ozone-depleting compound emissions have truly decreased since the passage of the Montreal Protocol. 

If handled responsibly, PFCs can be excellent choices to replace ozone-depleting compounds in many demanding, high-performance applications. Perfluorinated liquids are colorless, odorless, essentially nontoxic, and nonflammable. In addition, since they are not precursors to photochemical smog, PFCs are exempt from the U.S. EPAs volatile organic compounds (VOC) definition. Most importantly, these materials do not contain the carbon-bound chlorine or bromine, which can cause ozone depletion. 

Table 11 Ozone-Depleting Compounds Destroyed by the Na/NH3 CFC Destruction Process3...

Stratospheric ozone Emission of ozone-depleting compounds (CFCs, Halons) Chemical reaction release of C1 and Br in stratosphere Catalytic destruction of ozone in stratosphere Skin and crop damage, damage to materials Ozone Depletion Potential (ODP)... 

Selective dehydrochlorination of chlorofluorocarbons (CFCs) is a very important environmental issue, and the need to replace these detrimental, ozone-depleting compounds by benign hydrochlorofluorocarbons (HCFCs) and/or hydrofluorocarbons (MFCs) has stimulated intensive work on the subject [172-182]. Palladium has been the most extensively investigated catalytic metal in this reaction, but the moderate selectivity for CH2F2 exhibited by Pd/Si02 (40%) can be significantly increased, up to 95%, with a 20-40 at%. Au addition [180], and, in Pd/C, from 70% to 90% with Au addition [181,182]. 

Gibbs MJ, Wasson J, Magee T, et al. 1992. Study of emissions and control of stratospheric ozone-depleting compounds in California. ICF Consulting Association. Inc., Universal City. CA. USA. 305 pp. NTIS No. PB93-160752. 

In 1995 the Nobel Prize for chemistry was awarded to F. Sherwood Rowland and Mario Molina, physical chemists from the University of California, Irvine. In then-published ozone depletion hypothesis [1], they proposed that chlorine atoms could form high in the stratosphere. As an offshoot of this work as well as some other work, the Montreal Protocol on Substances That Deplete the Ozone Layer was signed in 1987. The treaty took effect on January 1, 1989, and has since undergone several revisions. The treaty addresses ozone-depleting compounds that contain chlorine or bromine. Fluorine is not included in the treaty because it has not been shown to harm the ozone layer. 

What chemical properties of a nitrous oxide molecule allow a researcher to consider this as both a global warming and an ozone-depleting compound ... 

Most Asian countries are parties to the Vienna Convention and Montreal Protocol on ozone depleting compounds. The Montreal Protocol is exemplary in the sense that it truly embodies the principles of common but differentiated responsibility between the industrial and developing countries. It recognizes the fact that industrialized countries are responsible for the bulkof emissions ofCFC. Moreover, they have the financial and technological resources to find proper replacements for these substances. Meanwhile, the developing countries are given a period of grace before they must start their phase-out schedules. 

The easy availability of substitutes is a factor that permitted compliance to the Protocol. Science and industry have been able to develop and commercialize alternatives to the CFCs and other ozone-depleting compounds. In fact, industrialized countries like Japan and Singapore ended their dependence on CFCs at less cost than was anticipated. 

The list of compounds includes those identified in the Montreal Protocol as contributing to ozone depletion, since these compounds also contribute to global warming. It also includes compounds used or proposed as replacements for the ozone-depleting compounds but which stUl have global warming potential. 

These compounds reach the stratosphere because they are so unreactive in all tropospheric processes, including reactions with HO- to which they are virtually inert. Measurements of atmospheric ozone in Antarctica (Stolarski et al., 1986), in the Arctic (Zurer, 1990), and even in the temperate latitudes (Watson et al., 1988) all point to a decrease in stratospheric ozone concentrations. Recent attempts to diminish the use of ozone-depleting compounds on a global basis appear to have been successful however, only minor effects on the rate of ozone destruction are likely to be observed for many years to come. 

Protection of Stratospheric Ozone ozone-depleting compounds chloro fluorocarbons... 

The Montreal Protocol (1987) has restricted the production and use of several classes of ozone-depleting compounds (ODS) including the original suspect, the CFCs. In July of 1992, the EPA issued its final rule implementing section 604 of the Clean Air Act Amendments of 1990, which limit the production and consumption of ozone-depleting substances. The rule requires industry to reduce production of Class I ODSs and to phase them out completely by January 1, 2000... 

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