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Photomicrograph made with a scanning electron microscope and back-scatter detector: cross section of fly ash particles. Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK)—plurale tantum: coal combustion residuals (CCRs)—is a coal combustion product that is composed of the particulates that are driven out of coal-fired boilers together with the flue gases.
The Marsh test treats the sample with sulfuric acid and arsenic-free zinc. Even if there are minute amounts of arsenic present, the zinc reduces the trivalent arsenic (As 3+). Here are the two half-reactions: Oxidation: Zn → Zn 2+ + 2 e − Reduction: As 2 O 3 + 12 e − + 6 H + → 2 As 3− + 3 H 2 O. Overall, we have this reaction:
AsH 3 is used in the synthesis of semiconducting materials related to microelectronics and solid-state lasers. Related to phosphorus, arsenic is an n-dopant for silicon and germanium. [8] More importantly, AsH 3 is used to make the semiconductor GaAs by chemical vapor deposition (CVD) at 700–900 °C: Ga(CH 3) 3 + AsH 3 → GaAs + 3 CH 4
Coal ash contains many toxic substances that may affect human health, if people are exposed to them above a certain concentration in the form of particulate matter.So it is necessary to avoid situations in which employees working in coal-fired power plants or public members living close to coal ash landfills will be exposed to high coal ash dust concentrations. [4]
Arsinides react with water to yield arsine AsH 3: KAsH 2 + H 2 O → KOH + AsH 3 [ 6 ] Potassium dihydrogen arsinide KAsH 2 reacts with halobenzenes C 6 H 5 X , where X = Cl, Br, I ( chlorobenzene C 6 H 5 Cl , bromobenzene C 6 H 5 Br , iodobenzene C 6 H 5 I ) to produce benzene C 6 H 6 , tetraphenyldiarsine (C 6 H 5 ) 2 As−As(C 6 H 5 ) 2 and ...
One idea is to react carbon dioxide, produced perhaps by the combustion of coal, to form solid carbonates (such as sodium bicarbonate) that could be permanently stored, thus avoiding carbon dioxide emission into the atmosphere. [20] [21] The Solvay process could be modified to give the overall reaction: 2 NaCl + CaCO 3 + CO 2 + H 2 O → 2NaHCO ...
The behaviour of the coal's ash residue at high temperature is a critical factor in selecting coals for steam power generation. Most furnaces are designed to remove ash as a powdery residue. Coal which has ash that fuses into a hard glassy slag known as clinker is usually unsatisfactory in furnaces as it requires cleaning. However, furnaces can ...
The combustion of coal releases diverse chemicals into the air. The main products are water and carbon dioxide, just like the combustion of petroleum. Also released are sulfur dioxide and nitrogen oxides, as well as some mercury. The residue remaining after combustion, coal ash often contains arsenic, mercury