Material selection environmental effects

The analytical procedures applied at Level 2 may be extensions of the Level 1 procedures. In most cases, however, Information developed at Level 1 will provide background for selection and utilization of more sophisticated sampling and analysis techniques. Because Level 2 analyses must positively identify the materials in sources which have already been found to cause adverse environmental effects, these analyses are the most critical of all three levels. It is equally important, however, that the analyses be conducted in an information-effective manner. This is because increasing specificity and accuracy result in cost escalations which are, at best, exponential rather than proportional. Due to the multiplicity of analytical techniques required and the potential for unnecessarily high expenditures, the analyses must be conducted with a full awareness of the information requirements of the environmental assessment program. 

Because solvents are required in such high volumes compared to all other materials used in a synthetic transformation, hazards associated with solvents and safety issues associated with their use have always been a consideration in the development and selection of solvents. Some of the earliest and most obvious hazards, that if solvents were found to possess would cause them to be selected against, include properties such as high flammability or explosivity. With the greater understanding of the health and environmental effects that could be caused by other hazardous properties that solvents may possess or by their use in such large volumes, alternative solvents are... 

The corrosion engineer can play a major role in system design, material selection, process or environmental control, and remediation. The focus of these efforts should not necessarily be the complete elimination or avoidance of corrosion, but rather the selection of the most cost-effective means of corrosion control and abatement. 

It is important to note that LCA is a tool to evaluate all environmental effects of a product or process throughout its entire life cycle. This includes identifying and quantifying energy and materials used and wastes released to the environment, assessing their environmental impact, and evaluating opportunities for improvement. LCA can also be used in various ways to evaluate alternatives including in-process analysis, material selection, product evaluation, product comparison, and policy-... 

Ashby [16] has created material selection charts displaying property clusters for different material t5rpes by plotting one property against another (for example, modulus versus relative cost). These charts are overlaid with the contours for applications-based property indices (such as modulus over density times cost), as schematically displayed in Figure 5.5. This permits selection of materials according to application specifications. These charts have been developed for several important mechanical and thermal properties and for the easiest environmental effect to measure, namely energy. It would be feasible to expand these charts to include further environmental parameters, if quantitative measures of environmental impact were to be developed. 

Membrane materials usually get selected for building construction on the basis of properties such as mechanical strength, cost, flexibility, process-ability, cleaning behaviour, durability and resistance to UV light, fire, humidity and chemical attacks or other fouling behaviour, besides their ecological and environmental effects. 

Silverman, E., Space Environmental Effects on Spacecraft LEO Materials Selection Guide, NASA CR-4661 (Aug. 1995)... 

Seven primary corrosion prevention methods are available to reduce the corrosion of metals material selection, electrical isolation, electrical bonding, environmental modification, inhibitors, coatings, and cathodic protection. Corrosion prevention methods are often used in conjunction with one another. Coatings are used to reduce current requirements in cathodic protection. Zinc is used as a cathodic protection system in coatings. The effects of two or more corrosion prevention systems can be synergistic or antisyner-gistic. Two effects are synergistic if the combination of the two is more effective than the sum effect of the two. 

Methods to evaluate materials performance are used both for materials selection and for failure analysis. Materials selection cein be based on field surveys, exposure tests in commercial units, or laboratory test results [27]. Field surveys represent long-term results from actual test environments, but the environmental conditions usually are not well-defined or constant. Exposure tests in commercial units may or may not be realistic, depending upon the test method approach. This point is discussed in the next section. Laboratory tests with simulated flue gas run the risk of missing the effects of trace constituents, which typically are not present in simulated environments. Laboratory tests with selected trace elements may not be indicative of the effect of these elements on materials performance in the field. 

Although the methods of production of bulk chemicals often suffer from low selectivity and/or productivity per pass, they continue to be the major methods for the synthesis of carbonyl compounds as the formed by-products are also demanded chemicals. However, such protocols are not economically attractive for the production of specific carbonyl compounds in the fine chemicals industry, where the selective and effective oxidation of valuable starting materials (e.g., alcohols) to the corresponding carbonyl compounds is required. Hence, the development of alcohol oxidation methods in fine chemicals industry directs toward achieving highly selective, efficient, and environmentally friendly catalytic systems... 

The method used for resist stripping must be carefully evaluated when a resist is selected. The effect on board materials, cost and prodnction requirements, and compliance with safety and pollution standards must be taken into account. Solvent-based stripping solutions are under significant environmental pressure. Chlorinated solvents and cychc compounds (toluene, xylenes, etc.) have been banned, and many glycol ethers are restricted. In spray applications, care must be taken to capture or ehminate VOC emissions. For these reasons, aqueous or primarily aqueous stripping systems are necessarily widely used. 

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