Carbon dioxide primary pollutant

Combustion processes are the most important source of air pollutants. Normal products of complete combustion of fossil fuel, e.g. coal, oil or natural gas, are carbon dioxide, water vapour and nitrogen. However, traces of sulphur and incomplete combustion result in emissions of carbon monoxide, sulphur oxides, oxides of nitrogen, unburned hydrocarbons and particulates. These are primary pollutants . Some may take part in reactions in the atmosphere producing secondary pollutants , e.g. photochemical smogs and acid mists. Escaping gas, or vapour, may... 

Emissions to the atmosphere from ammonia plants include sulfur dioxide (SOj), nitrogen oxides (NOJ, carbon monoxide (CO), carbon dioxide (COj), hydrogen sulfide (HjS), volatile organic compounds (VOCs), particulate matter, methane, hydrogen cyanide, and ammonia. The two primary sources of pollutants, with typical reported values, in kilograms per ton (kg/t) for the important pollutants, are as follows ... 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

Rain unaffected by human activity contains mostly weak acids and has a pH of 5.7. The primary acid present is carbonic acid, H2C03, a weak acid that results when atmospheric carbon dioxide dissolves in water. The major pollutants in acid rain are strong acids that arise from human activities. Atmospheric nitrogen and oxygen can react to form NO, but the endothermic reaction is spontaneous only at the high temperatures of automobile internal combustion engines and electrical power stations ... 

Once formed, the primary redox products are converted in subsequent thermal reactions steps to the final compormds Area and Dox- When oxygen is the electron acceptor and a pollutant like phenol is the electron donor, carbon dioxide and water are the final redox products (Scheme 2). The primary reductive redox product is superoxide which can be converted to the strongly oxidizing OH radical via protonation, disproportionation of HO2 and reductive photocleavage of the produced H2O2. Instead of water oxidation, the oxidative primary step may consist of the oxidation of the pollutant producing a phenoxy radical and a proton. Such complete photooxidation reactions are often termed as mineralization and in general titania is employed as the photocatalyst 4-7). 

Phenol, a common priority pollutant, was extracted from two environmental matrices, soil and water, using near critical and supercritical carbon dioxide. The primary objective of this study was to determine the distribution of the contaminant between the soil or water and the supercritical phase, and the effect of soil moisture and co-solvents on the distribution coefficients. Static equilibrium extractions were performed on dry and wetted soil contaminated with 1 wt.% phenol and on water containing 6.8 wt.% phenol. Supercritical carbon dioxide (with and without en-trainers) was chosen as the solvent for the study. An appropriate entrainer for dry soil extractions (methanol) ffiffered from that found for aqueous extractions (benzene). However, soil moisture was found to have a significant impact on the effectiveness of en-trainers for soil extractions of phenol. Entrainers appropriate for extracting wetted soil were found to be the same as those advantageous for aqueous extractions. Benzene was also extracted from dry and wetted soil to investigate the extractability of a hydrophobic compound. 

The primary argument in favor of renewable energy is that it does not entail the release of chemical pollutants to convert the energy. This is in contrast to fossil fuels, which emit a range of pollutants from carbon dioxide (CO2) to the components of acid rain to ash. Table 1 shows the pollutants from typical 2000 MW plants. 

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