Emission , restrictions

The persistence of ozone pollution may result in additional emission restrictions for industry. Because of aggressive emissions reduction programs in the past, industrial emissions represent a minority share of total emissions, typically in the range of 15—20%. Despite this success in reducing emissions, it is hkely that large industrial emission sources, including industrial solvent emissions, will have additional controls imposed because those plants still represent the easiest targets to obtain further reductions. 

Solvent emission restrictions, as for other coating systems, have also given rise to the development of water-borne, HS, radiation cured and powder PU coating systems. The various techniques which are used to obtain anionic, nonionic and cationic emulsions have been reviewed in the literature. Curing of cationic latex takes place either by reaction of water " with the terminal isocyanate groups or by reaction with water-soluble diamines according to reactions (49) and (50). 

By far the preferred way to resolve the policy makers dilemma is to lower the emissions of the greenhouse gases. However, so far, attempts in that direction have been grossly unsuccessful. While stabilization of CO2 would require a 60-80 % reduction in current anthropogenic CO2 emissions, worldwide they actually increased by 2 % from 2001 to 2002 (Marland et al. 2005), a trend, which probably will not change at least for the remaining 6-year term of the Kyoto protocol, further increasing the required emission restrictions. 

Photoexcited fluorescence from spread monolayers may be studied [158,159] if the substance has both a strong absorption band and a high emission yield as in the case for chlorophyll [159]. Gaines and co-workers [160] have reported on the emission from monolayers of Ru(bipyridine)3, one of the pyridine ligands having attached C g aliphatic chains. Ruorescence depolarization provides information about the restriction of rotational diffusion of molecules in a monolayer [161], Combining pressure-area... 

Trace-element analysis of metals can give indications of the geographic provenance of the material. Both emission spectroscopy (84) and activation analysis (85) have been used for this purpose. Another tool in provenance studies is the measurement of relative abundances of the lead isotopes (86,87). This technique is not restricted to metals, but can be used on any material that contains lead. Finally, for an object cast around a ceramic core, a sample of the core material can be used for thermoluminescence dating. 

Urea—formaldehyde use has been greatly restricted because of free formaldehyde (qv) emissions which can cause eye irritation and in some cases serious illness. Some attempts at developing formaldehyde-free urea-based materials are ongoing. 

Regulations have a significant impact on the selection and use of industrial solvents. Since 1966, new and more restrictive regulations have been adopted at both the federal and the state levels, which influence the kind of solvents used, the amount used, and the way they are used. Regulations have given impetus to the development of new technologies and products which decrease solvent emissions to minimise environmental impact. 

Reformulating to reduce HAP solvents frequently means that solvent blend costs increase. The newer blends are generally not be as effective. For example, many coatings were usually formulated using ketones as the active solvents with aromatic hydrocarbons as diluents. This combination produced the most cost-effective formulations. However, when MEK, MIBK, toluene, and xylene became HAP compounds, less-effective solvents had to be used for reformulation. Esters are the most common ketone replacements, and aUphatic diluents would replace the aromatic hydrocarbons. In this situation, more strong solvent is required compared to the ketone/aromatic formulation and costs increase. The combination of reduced VOC emissions and composition constraints in the form of HAP restrictions have compHcated the formulator s task. 

The demand for trichloroethylene grew steadily until 1970. Since that time trichloroethylene has been a less desirable solvent because of restrictions on emissions under air pollution legislation and the passage of the Occupational Safety and Health Act. Whereas previously the principal use of trichloroethylene was for vapor degreasing, currentiy 1,1,1-trichloroethane is the most used solvent for vapor degreasing. The restrictions on production of 1,1,1-trichloroethane [71-55-6] from the 1990 Amendments to the Montreal Protocol on substances that deplete the stratospheric ozone and the U.S. 

AcryHc lacquers also have disadvantages the gloss of the air-dry film is too low and the surface must be mbbed to achieve the high gloss necessary for automotive top coats and most importantly, VOC emissions are very high. AcryHc lacquers are expected to be phased out when controls become more restrictive. 

Based on dryer cost alone, indirect-heat dryers are more expensive to build and install than direct-heat dryers designed for the same duty. As environmental concerns and resulting restrictions on process emissions increase, however, indirect-heat dryers are more attractive because they employ purge gas only to remove vapor and not to transport heat as well. Dust and vapor recovery systems for indirect-heat dryers are smaller and less cosdy to supply heat for drying, gas throughput in direct-heat dryers is 3—10 kg/kg of water evaporated indirect-heat dryers require only 1—1.5 kg/kg of vapor removed. System costs vary directly with size, so whereas more money may be spent for the dryer, much more is saved in recovery costs. Wet scmbbers ate employed for dust recovery on indirect-heat dryers because dryer exit gas usually is close to saturation. Where dry systems are employed, all external surfaces must be insulated and traced to prevent vapor condensation inside. 

Latex Adhesive Applications. Polychloroprene latex adhesives have a long history of use in foil laminating adhesives, facing adhesives, and constmction mastics. Increasingly stringent restrictions on the emission of photoreactive solvents has heightened interest in latex compounds for broader apphcations, particularly contact bond adhesives. Table 10 makes a general comparison of solvent and latex contact bond adhesives (158). 

In addition, restrictions on industrial air emissions under the Clean Air Act (CAA) as amended in 1977, the Clean Air Act Amendments (CAAA) of 1990, and other state and local statutes and regulations have universal impact on the storage of toxic materials, with direct and significant effects on the design and operation of toxic material storage facilities. Whereas the primary factors which once determined how air emissions from storage tanks were handled were fire protection and loss prevention, in recent years environmental protection concerns nearly always determine the extent and nature of the air emission controls required to be installed. 

Control of emissions by restricting activities or product composition... 

The states and cities of the United States sometimes have emission standards for existing installations, which are usually less restrictive than those... 

Existing stationary sources may require modification of existing systems or installation of newer, more efficient control devices to meet more restrictive emission standards. Such changes are often required by control agencies when it can be shown that a new control technology is superior to older... 

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