Environmentally friendly techniques

Environmentally friendly techniques for climate protection, hence, contribution to environmental conservation—commitment for reduction of CO2—obligations of Convention on Climate Change, Kyoto Protocol. 

The results presented here demonstrate the first successful applications of the concept of electroenzymatic synthesis. However, it is also obvious that many more systems are potentially very interesting for synthetic applications. This area is wide open for further creative research and only the tip of the iceberg has surfaced. What is especially promising is the fact that electroenzymatic synthesis is an environmentally friendly technique using the electrode as a clean reagent and the enzymes for high selectivity. Closed systems for technical applications are easier to realize than in many other areas. The author is convinced that industrial syntheses of valued small scale products will be seen in the near future. 

Photocatalysis over oxide semiconductors has been proposed as an effective, mild and environmental friendly technique for the abatement of (refractory) organic contaminants with oxygen as electron acceptor [15]. In this case the reaction is normally exoergonic, as the overall reaction (mineralization) is organics + yC>2 = xCC>2 + ZH2O. 

The decontamination of polluted waters by photocatalytic treatment has been suggested as a viable, low-cost, and environmental friendly technique. The possibility of using solar energy as well as low-cost technology pushed to develop solar plants based on this process. The field results are very encouraging [1]. 

Labour Household, work day exchange with other households Household labour dominant. With exchange labour but on the decline. Start of hired labour Household labour coupled with a few pockets of exchange labour. Increase in hired labour Frequent lack of labour for environmental friendly techniques. Household labour continue being the norm. Hired labour limited for additional farm work... 

As an alternative to traditional solvent extraction methods, the extraction by supercritical (SC) fluids has been used in tocol analysis. This is an environmentally friendly technique as little or no solvents are used. Extraction parameters, e.g. temperature and fluid density, are easily optimized and managed, and as the extraction is fast it is thus suitable for routine work with many samples. SC carbon dioxide has been used to extract tocols from barley (Fratianni et al, 2002), dried bay leaves (Gomez-Coronado et al, 2004), and garden cress seeds (Diwakar et al, 2010). Extractions were carried out in single or multiple steps and with different fluid densities controlled by extraction pressures. Tocol yields from barley were 5% and 14% less than by Soxhlet and chloroform-methanol extractions (Fratianni et al, 2002), yields from garden cress seeds were 26% less than by Soxhlet extraction (Diwakar et al, 2010), and a- and y-tocopherol yields from dried bay leaves were 22% and 40% less than by acetone extraction (Gomez-Coronado et al, 2004). Despite lower recoveries of tocols, the SC carbon dioxide extraction methods were considered comparable to the classical extraction methods (Fratianni et al, 2002). 

The newer extraction techniques such as SFE, MAE, and ASE are very attractive because they are a lot faster, use much smaller amounts of solvents, and are environmentally friendly techniques. For example, SFE uses carbon dioxide or modified carbon dioxide (e.g., carbon dioxide containing a small amount of an organic solvent known as modifier) for extraction. Carbon dioxide is a nontoxic, nonflammable, and environmentally friendly solvent. Furthermore, the extraction selectivity can be controlled by varying the pressure and temperature of the supercritical fluid and by the addition of modifiers. 

These adverse conditions can be improved to a certain degree limiting excavation to one section of the mining area at any one time, siting of boundaries and screening banks, erection of barriers, and use of low-noise machinery fitted with effective exhaust silencers. The implementation of environmentally friendly techniques has served to establish better public relations between the mining companies and the local populace. 

I don t really feel that I learned a ton about green chemistry specifically, so I don t see how different a green course would be. However, I feel that learning about environmentally friendly techniques would be valuable. It s fun and it s important to do our part in helping preserve the environment starting with education. 

Heterogeneous processes are of great importance for the free-radical chain-growth polymerization of CH2=CRR monomers on an industrial scale. In comparison with bulk polymerization, they allow us to overcome the rapid viscosity increase of the reaction medium with conversion, as well as its consequences, such as the difficult heat removal and the autoacceleration phenomenon. Because in many cases the continuous phase is water, they are also more environmentally friendly techniques than solution polymerization methods, where the use of organic solvents remains hazardous and expensive. Ultimately, heterophase polymerization techniques are the original routes to polymer particles ranging from a few tens of nanometers to a few millimeters in diameter. 

In situ metal immobilization employing phosphate is a cost-effective and environmental friendly technique of less disruptive nature [24, 28, 47, 76] than other remediation techniques such as soil removal, washing or leaching. This technique was suggested by the United States Environmental Protection Agency in 1996 as an alternative to soil removal for the amendment of urban lead-contaminated soils [27]. The treatment of waters with calcium oxide or hydroxide can precipitate dissolved arsenate. To attain a total dissolved arsenic level lower than the maximum permissible concentration for total arsenic in potable water (0.010 mg/L arsenic) it is necessary to have a pH higher than 12.5, which poses other environmental problems. Under these conditions calcium carbonate wiU be the thermodynamically stable solid phase under ambient surface conditions. Transformation of calcium arsenates into calcium carbonate wiU re-release arsenic into the environment. For pH > 12... 

Most commonly used plastics are cheap to manufacture and highly available [35], and are both physically and chemically stable [36]. The durability of these materials makes them ideal for a wide variety of applications, but is also one of the primary factors leading to their accumulation in the environment [37]. Currently, there are three plastic disposal methods in widespread use, each with its own inherent drawbacks. Disposal of plastic in landfill is the simplest of these methods, however there is potential for secondary pollutants to be released into groundwater [38], Similarly, incineration of plastic waste leads to the formation and subsequent release into the atmosphere of dangerous secondary pollutants[38]. Recycling is the most environmentally friendly technique, however it a more expensive process, and often additives and impurities make it extremely difficult for some plastics to be recycled [38]. 

Electrospinning has been considered recently to be one of the most promising eco-friendly techniques to fabricate nanomateiials. It is cheap and facile technique. Besides, it is counted as an environmentally friendly technique since if aU of the solvents used during electrospinning are eco-friendly, no harm can occur to the external environment. 

The lower amount of organic solvents (<2 ml) reqnired in SFE for an efficient extraction of contaminants from paper samples, compared with the liquid extraction, confirms SFE as a safer and environmental friendly technique. 

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