Carbon containing materials

Carbon dioxide, COj. Sublimes — 78 5 C. A colourless gas at room temperature, occurs naturally and plays an important part in animal and plant respiration. Produced by the complete combustion of carbon-containing materials (industrially from flue gases and from synthesis gas used in ammonia production) and by heating metal carbonates or by... 

Renewable carbon resources is a misnomer the earth s carbon is in a perpetual state of flux. Carbon is not consumed such that it is no longer available in any form. Reversible and irreversible chemical reactions occur in such a manner that the carbon cycle makes all forms of carbon, including fossil resources, renewable. It is simply a matter of time that makes one carbon from more renewable than another. If it is presumed that replacement does in fact occur, natural processes eventually will replenish depleted petroleum or natural gas deposits in several million years. Eixed carbon-containing materials that renew themselves often enough to make them continuously available in large quantities are needed to maintain and supplement energy suppHes biomass is a principal source of such carbon. 

Physiological Role of Citric Acid. Citric acid occurs ia the terminal oxidative metabolic system of virtually all organisms. This oxidative metabohc system (Fig. 2), variously called the Krebs cycle (for its discoverer, H. A. Krebs), the tricarboxyUc acid cycle, or the citric acid cycle, is a metaboHc cycle involving the conversion of carbohydrates, fats, or proteins to carbon dioxide and water. This cycle releases energy necessary for an organism s growth, movement, luminescence, chemosynthesis, and reproduction. The cycle also provides the carbon-containing materials from which cells synthesize amino acids and fats. Many yeasts, molds, and bacteria conduct the citric acid cycle, and can be selected for thek abiUty to maximize citric acid production in the process. This is the basis for the efficient commercial fermentation processes used today to produce citric acid. 

It appears that if homogeneous gels or coprecipitates can be obtained using carbon-based chemicals, they do not yield much better ceramics than conventional solid state synthesis. This is primarily attributed to the resulting carbonate-containing materials whose... 

Carbon Deposition. The term carbon deposition is used in the literature to refer to the accumulation of two distinct types of carbon-containing materials on the catalyst surface, both of which lead to deactivation."" The first can be described as elemental carbon, formed directly by one of several... 

The first documented successes occurred in 1953 and 1954. The earliest one was quiet and remained unannounced by cautious researchers at Sweden s main electrical company. The other was announced with fanfare in February of 1955 by the General Electric Company before the Department of Defense silenced the company for several years in the interest of national security. The youngest member of the GE diamondmaking teams, the freshly graduated Robert Wentorf, Jr., even found that he could convert peanut butter, a rather popular carbon-containing material in its own right, into diamond grit. 

Carbon monoxide (CO) is a colorless, odorless gas that is ubiquitous because it is created whenever carbon-containing materials are burned. Carbon monoxide poisoning is the leading cause of death due to poisoning in the USA. Most cases occur in victims of fires, but accidental and suicidal exposures are also common. The diagnosis and treatment of carbon monoxide poisoning are described in Chapter 56. Many other toxic gases are produced in fires or released in industrial accidents (Table 58-5). 

Radiocarbon Dating. This is a method of estimating Ihe age of carbon-containing materials by measuring the radioactivity of the carbon in them. The validity of this method rests upon certain observations and assumptions, of which the following statement is a brief summaiy. The cosmic rays entering the atmosphere undergo various transformations, one of which results in the formation of neutrons, which in turn, induce nuclear reactions in the nuclei of individual atoms of the adnosphere. The dominant reaction is... 

Tin can also combine with carbon-containing materials to form organotin compounds. These compounds are used in making plastics, food packages, plastic pipes, pesticides, paints, wood preservatives, and rodent (rats and mice) repellents. 

Several methods are known for the production of porous ceramics, such as partial sintering [8] or using specific sintering additives [9], An alternative method is to use fugitive additives such as carbon or other carbon-containing materials as additions, which has proven to be a successful technique for the preparation of high-performance porous ceramics [20],... 

Perchloric acid is effective in dissolving certain solids but is not used here because it poses an explosion hazard, notably with carbon. The acid should only be used to dissolve carbon-containing materials where perchloric acid hoods are available and the chemist is fully trained and certified to work with perchloric acid for this purpose. 

It is very useful to determine a mass balance for at least one element, comparing the amount of unconverted reactants and the amount of products. For a proper determination of kinetic parameters the mass balance should be closed at least up to 95%. Commonly carbon is used for the determination of the mass balance, as all carbon containing materials are rather easy to be quantified, compared to H2 or H2O, for example. 

The 14C isotope has a half-life of 5570 years. As a result of the half-life being so long, a relatively constant amount of 14C is contained in all carbon-containing materials. If a living... 

Trace quantities of carbon monoxide in the environment are considered normal (WHO 1999). Plants can both metabolize and produce this gas. Carbon monoxide is also produced by incomplete combustion of carbon-containing materials (ACGIH 1996), and automobile exhaust is a major source of carbon... 

Carbon black is not soot or black carbon, which are the two most common, generic terms applied to various unwanted carbonaceous by-products resulting from the incomplete combustion of carbon-containing materials, such as oil, fuel oils or gasoline, coal, paper, rubber, plastics and waste material. Most soot and black carbon species are ubiquitous in the environment as aerosols, sediments, and soils and have low... 

Usually only the carbon-containing materials and hydrogen from other sources are regarded as raw materials in the narrow sense because of the abundance of air, which... 

The major mechanism of generation of both the natural and anthropogenic StA is a pyrolysis in the gas- or condensed-phase of the carbon-containing material. The microphysical characteristics of the resulting StA depend on the specific nature of the source so, for instance, the particles produced by oil combustion have a coral-like structure and an effective spherical shape the pyrolysis of coal gives particles in the form of spheres, with a great amount of smaller, randomly oriented spheroids inside them [11]. 

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