Decomposition over charcoal

Calcium hexacyanoferrate (II) (IIH2O) [ 13821 -08-4] M 490.3. Recrystd three times from conductivity H2O and air dried to constant weight over partially dehydrated salt. [Trans Faraday Soc 45 855 1949.] Alternatively the Ca salt can be purified by pptn with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous soln. The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24h, then over partly dehydrated salt and stored in a dark glass stoppered bottle. No deterioration occurred after 18 months. No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with cone H2SO4. Analyses indicate 1 Imols of H2O per mol of salt. The solubility in H2O is 36.45g (24.9 ) and 64.7g (44.7 ) per lOOg of solution. [J Chem Soc 50 1926.]... 

Kinetic parameters of fast pyrolysis were derived while assuming a single process for the decomposition of wood, including three parallel first-order decay reactions for the formation of the product classes. This is the so-called Shafizadeh scheme [56]. The three lumped product classes are permanent gas, liquids (biooil, tar), and char a classification that has become standard over the years. The produced vapors are subject to further degradation to gases, water and refractory tars. Charcoal, which is also being formed, catalyzes this reaction and therefore needs to be removed quickly [57]. 

Basic techniques for producing charcoal have not changed over the years although the equipment has. Charcoal is produced when wood is burned under conditions in which the supply of oxygen is severely limited. Carbonization is a term that aptly describes the thermal decomposition of wood for this application. Decomposition of carbon compounds takes place as the temperature rises, leading to a solid residue that is richer in carbon than the original material. Wood has a carbon content of about 50 percent, whereas charcoal of a quality suitable for general market acceptance will be analyzed as follows fixed carbon 74-81 percent, volatiles 18-23 percent, moisture 2-4 percent, and ash... 

The relative portion of arsenic in wood charcoal was over 75 %, and independent of temperature up to 450 °C. It decreased markedly to 60 % at 500 C. The total pyrolysis time caused no significant difference at temperatures between 350 and 450 °C. It is believed that arsenic is strongly bound to cellulose and lignin [1] The decomposition of both chemical components occurs as temperature or the total pyrolysis time increase, resulting in more arsenic compounds being released The combination of a temperature between 350 and 450 C and total pyrolysis time of 200 s and lower is optimal for maintaining arsenic in the wood charcoal under these experimental conditions. 

The gas phase reaction of phosgene with ethane-1,2-diol over activated charcoal results in the formation of 1,2-dichloroethane with a yield of about 70% at 210 C higher temperatures caused the decomposition of the diol [1C186]. 

In cases where a compound A B cannot be decomposed by a body C, even with the aid of a high temperature, the addition of a fourth body D, if it have an affinity for A, while there is an affinity between C and B, will often enable us to accomplish the decomposition. Thus, oxide of aluminum cannot be decomposed by charcoal even at a white heat but when a current of chlorine gas is passed over the mixture, the chlorine by virtue of its affinity for aluminum, added to that of carbon for oxygen, effects the decomposition, and we obtain chloride of aluminum and oxide of carbon. 

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