Volatilization moisture determination

In studies on the moisture determination of corn by vacuum drying at 100° C., Sair and Fetzer (28) found that an error of about 0.5% in moisture content could be attributed to volatility of oils. The error was negligible in vacuum drying at 70° C. 

Inherent or equilibrium moisture is used for calculating moist, mineral-matter-free calorific values for the rank classification of high-volatile bituminous coals. It is also used for estimating free or surface moisture, since total moisture is equal to the sum of the inherent moisture and the free moisture and is considered the inherent moisture of the coal as it occurs in the unexposed seam, where the relative humidity is probably near 100%. However, due to physical limitations, equilibrium moisture determinations are made at 96 to 97% relative humidity and used as inherent moisture values. 

Determine amount of ash, fixed carbon, moisture, and volatile matter Determine rank and how well a coal will fmm coke Determine inherent water and any other water present Identify trace elements... 

A common practice is to determine ash content on samples that have been oven-dried for moisture determination. While ash may be used for determination of metals, salts, etc., attention must be given to the possibility of losses due to volatility of these components of the sample at the very high ashing temperatures used. 

Volatile matter (VM) represents the mass percentage of compounds contained in the coal or coke given-off upon heating at 950°C but excluding moisture. In practice, it corresponds to the weight loss other than moisture determined on the sample as received according to standard ASTM D3175. 

Microwave analysis of moisture is also known as LOD (loss on drying), drying test, or total volatile solids. For many years, the standard oven test was used for moisture determination. Although very accurate, the test could take many hours to complete, depending on the sample. The time lapse rendered it practically useless for anything except a final quality control check. The new microwave moisture/solids analyzers were introduced about 20 years ago. They offer rapid, accurate moisture/solids analysis in a fraction of the time it took to run a standard oven-drying test. 

The conversion factors for the individual bases are given in Table 3.3. Any quantity from a proximate or ultimate analysis (X) can be converted from the given basis by multiplying with the indicated factor to a new desired basis. As an example, Equation (3.3) shows the conversion of the volatile matter determined at air-dried basis VM(ad) to water-and-ash-free basis, taking moisture W(ad) and ash A(ad) into account. 

Thermal analysis has been used in a variety of areas including studies on thermal decomposition, moisture determination, volatile compounds, thermal oxidation, reaction kinetics, crystallization, phase diagrams, specific heat determination, vitreous transition determination, and storage time determination, among others [12]. 

Liquid flavors are encapsulated in solid carriers to protect them from oxidation, volatilization, moisture, etc. There are numerous methods for encapsulation as well as types of solid carriers that are utilized. Spray drying and extrusion are the two most widely used techniques. Both methods typically encapsulate the flavor with some form of modified starch or sugar. It is necessary to monitor the performance of any encapsulation technique by determining the actual flavor loading versus the theoretical load. 

When thermal or chemical energy is used to remove a volatile species, we call the method volatilization gravimetry. In determining the moisture content of food, thermal energy vaporizes the H2O. The amount of carbon in an organic compound may be determined by using the chemical energy of combustion to convert C to CO2. 

The moisture content of cmde sulfur is determined by the differential weight of a known sample before and after drying at about 110°C. Acid content is determined by volumetric titration with a standard base. Nonvolatile impurities or ash are determined by burning the sulfur from a known sample and igniting the residue to remove the residual carbon and other volatiles. 

Analysis. The proximate analysis is based on determinations of volatile matter, moisture, and ash for a coal sample. Fixed carbon is then calculated by difference. Volatile matter is determined empirically by measuring the weight loss when coal is heated in a covered cmcible at either 950°C (ASTM D3175 or D5142) or 900°C (BS). 

Ash. After the sample is heated ia a cmcible over a hot plate to drive off volatile solvents and moisture, it is charred over a Bunsen burner and then transferred to a muffle furnace where final ignition is completed. The weight of the ash is determined and reported as a percentage of the weight of the original sample. 

Proximate analysis - a relatively low-cost analysis in which moisture content, volatile combustible matter, fixed carbon, and ash are determined. The fuel value of the sludge is calculated as the weighted average of the fuel values of its individual components. 

Simkins J. Squire, The Rapid Determination of Volatile Matter by the Mytron FAB-1 Moisture Meter , Explosive Research Development Establishment TN 82 (1973) 56) Anon, Ex-... 

Table 3 shows some physicochemical properties used as international GA quality parameters, for example moisture, total ash content, volatile matter and internal energy, with reference to gums taken from Acacia Senegal species in Sudan (FAO, 1990, Larson Bromley, 1991). The physicochemical properties of GA may vary depending on the origin and age of trees, the exudation time, the storage type, and climate. The moisture content facilitates the solubility of GA carbohydrate hydrophilic and hydrophobic proteins. The total ash content is used to determine the critical levels of foreign matter, insoluble matter in... 

The composition of coal is conveyed by representing its proximate and ultimate analysis. The former implies determination of contents of moisture, volatile matter, fixed carbon, and ash, while the latter implies total carbon, hydrogen, oxygen, nitrogen, sulfur and ash. Here, an account will be provided of the constituents of coal, moisture, volatile matter, ash, fixed carbon, and some miscellaneous components. 

Thermogravimetry (TG) is a measure of the thermally induced weight loss of a material as a function of the applied temperature [39], Thermogravimetric analysis is restricted to studies involving either a mass gain or loss, and it is most commonly used to study desolvation processes and compound decomposition. Thermogravimetric analysis is a very useful method for the quantitative determination of the total volatile content of a solid, and it can be used as an adjunct to Karl Fischer titrations for the determination of moisture. 

The characteristics of coals that determine classification and suitability for given applications are the proportions of volatile matter, fixed carbon, moisture, sulfur, and ash. 

Note if determinations of certain volatile elements such as mercury or selenium are required it is necessary to carry out these analyses on the wet sample as received (to avoid loss of element by drying at 105°C). The dry weight of material in the sample is obtained by determining moisture in a separate position of the sample and applying a correction to the sample weight used in metals determination. 

In the United Kingdom, standard quality testing before using gunpowder includes a determination of the volatile matter (which is mainly moisture) by oven drying under controlled conditions. As a general guide, the moisture level determined in this way would be expected to fall between 0.5 and 1.4% for an acceptable powder. 

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