Search results
Results from the WOW.Com Content Network
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:
A coal-fired power plant with ash ponds. Coal ash, also known as coal combustion residuals (CCRs), is the mineral residue that remains from burning coal. Exposure to coal ash and to the toxic substances it contains may pose a health risk to workers in coal-fired power plants and residents living near coal ash disposal sites.
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 ...
Upon reaction with the aluminium trialkyls, AsH 3 gives the trimeric [R 2 AlAsH 2] 3, where R = (CH 3) 3 C. [15] This reaction is relevant to the mechanism by which GaAs forms from AsH 3 (see below). AsH 3 is generally considered non-basic, but it can be protonated by superacids to give isolable salts of the tetrahedral species [AsH 4 ] + .
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 ...
Arsenic is also a common n-type dopant in semiconductor electronic devices, and a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the ...
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 ...