Hazardous byproduct, environmental

Although MBE continues to be the best technique for controlled deposition of thin layers (10-100 A) of materials, the MOCVD process does offer the advantage for rapid deposition over large areas of substrates. The basic principles of the MOCVD technique is the thermal decomposition of volatile molecular precursors to the desired combined form (or even the constituent metal itself) on a selected substrate at not too high a temperature. In addition to the volatility of the precursor and its facile decomposition to the desired combined form for deposition, the whole operation should not, from the practical point of view, involve any toxic/hazardous byproducts, that might entail any environmental problems. 

Recent Advances in Indirect Electrochemical Synthesis. Indirect electrochemical synthesis has tremendous potential as an environmentally benign procedure since the selectivity of a chemical reaction can be obtained without the production of toxic or hazardous byproducts. Two recent reviews (50, 57) exhaustively cover the field through the mid 1980 s. Before describing our results, we will briefly survey recent advances in the field. 

Gas plasma is an attractive sterilization method because it does not leave toxic residues or involve environmentally hazardous byproducts (Feldman and Hui 1997, Kyi, Holton, and Ridgway 1995). Based on product literature available from the manufacturer, the sterilization cycle time for the Plazlyte system is 3 to 4 hours the Sterrad system has an even shorter sterilization cycle of 75 minutes (Feldman and Hui 1997, Kyi, Holton, and Ridgway 1995). Because no lengthy aeration period is required after gas plasma sterilization, it potentially offers substantial time and cost savings over EtO sterilization (Feldman and Hui 1997). Because of its recent introduction, retrieval data from in vivo gas plasma sterilized UHMWPE components are not yet available. 

Bioremediation. Bioremediation has great appeal. It is a natural process that degrades hazardous organic chemicals into innocuous carbon dioxide and water or nonhazardous byproducts and it is often less expensive and more effective than pump and treat methods. Articles on bioremediation appear regularly in environmental journals and the U.S. EPA has its own regular series of reports on current activities called "Bioremediation in the Pield."... 

The systems produce no harmful emission, harmful or radioactive byproducts, hazardous wastes, or biospheric pollutants. As usage is phased in worldwide, a significant reduction of environmental pollutants and hazardous wastes will result, as will a cleaner biosphere. 

This process is generally practical and experimentally convenient, and can be performed in a variety of solvents, including water. The reaction is also environmentally friendly or green since it does not require hazardous or toxic chemicals, while the boric acid byproduct of the reaction has a relatively small molecular weight and can be readily removed. 

This adipic acid synthesis poses environmental and health concerns because it has benzene as a starting material. Benzene is a volatile organic compound and its inhalation can lead to leukemia and cancer. This compound, therefore, is often an occupational hazard to those who work with it or come in contact with it. Moreover, benzene is a byproduct of petroleum manufacture thus, it is produced from a non-renewable source. 

Catalytic hydrotreatment is widely used in the petroleum Industry to remove sulfur, nitrogen, and oxygen from crude oil fractions. However, its use to treat chlorocarbons has not been widely reported despite the widespread use of these compounds in industrial and military operations, and despite the negative environmental impact associated with most disposal options. Catalytic hydrotreatment has the potential to be a safe alternative for the treatment of chlorinated wastes and has advantages over oxidative destruction methods such as thermal incineration and catalytic oxidation. Some of these advantages include the ability to reuse the reaction products, and minimal production of harmful byproducts, such as CI2, COCI2, or fragments of parent chlorocarbons. 1,1,1- Trichloroethane was chosen for this research because it is widely used in industry as a solvent and is on the EPA Hazardous Air Pollutant list as a toxic air contaminant and ozone depleter. ... 

Nitrous oxide is produced as a byproduct in multimillion Ib/year quantities in nylon manufacture worldwide. Currently, there is a great interest toward the utilization of NjO due to the environmentally hazardous nature of this gas with respect to the greenhouse effect and ozone layer depletion. In addition to their ability to utilize dioxygen for catalytic hydrocarbon oxidations, ruthenium porphyrins have been shown to activate nitrous oxide which is an extremely inert molecule and a poor ligand. Groves and Roman have found that N O reacted with Ru"(TMP)(THF)2 in toluene to produce Ru (TMP)(0)2 . trans-dioxoRu(VI) complex can in turn epoxidize a suitable substrate such as tra/js-p-methyl styrene. This system was subsequently shown to be catalytic under appropriate conditions . 

This compound is a potential environmental hazard that is formed as a contaminating byproduct in the manufaeture of herbicides. 

It was also reported that PPy could be polymerized using nontoxic supercritical fluids as solvents. In conventional chemical polymerization, incorporation of the oxidant into the polymerization process and/or washing to remove unwanted byproducts generates a large amount of environmentally hazardous solvent. In the process using supercritical fluid, which is nontoxic, nonflammable, and environmentally acceptable, PPy was polymerized within preformed polyurethane (PU) foam using supercritical carbon dioxide as solvent [41]. 

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