Gravimetric filling

Isotherm measurements of methane at 298 K can be made either by a gravimetric method using a high pressure microbalance [31], or by using a volumetric method [32]. Both of these methods require correction for the nonideality of methane, but both methods result in the same isotherm for any specific adsorbent [20]. The volumetric method can also be used for measurement of total storage. Here it is not necessary to differentiate between the adsorbed phase and that remaining in the gas phase in void space and macropore volume, but simply to evaluate the total amount of methane in the adsorbent filled vessel. To obtain the maximum storage capacity for the adsorbent, it would be necessary to optimally pack the vessel. 

The NaCl -SOD formed during these reactions can be clearly identified by its IR spectrum, perchlorate sodalite collapse at 1050°C. From the thermo gravimetric analysis it is evident that at this temperature the entire amount of NaCl escapes. The degree of the cage filling by salt molecules can be calculated on the basis of both the oxygen and the NaCl loss. 

Sampling accuracy Determine gravimetrically the average volume of water withdrawn from a tared vial filled with water after six 50- lL injections 50 2pL... 

The autosampler injection accuracy test involves the gravimetric determination of the average volume of water withdrawn from a tared vial filled with water after six 50- uL injections. The procedure, adopted from a manufacturer s OQ, takes less than 10 min and has an acceptance criterion of 50 2 J,L (Figure 9). 

Volumetric systems are calibrated by weighing the amount of mercury required to fill internal volumes. Gravimetric systems are calibrated using reliably known weights and should be recalibrated occasionally to insure... 

The mass of a gravimetric precipitate is measured by weighing a dry, empty filter crucible before the procedure and reweighing the same crucible filled with dry product after the procedure. To weigh the empty crucible, first bring it to " constant mass by drying it in the... 

Sorption Properties. Sorption isotherms were determined of n-hexane and 2,3-dimethylbutane on variously pretreated samples of zeolite by a gravimetric method using a Cahn electrobalance. No shape-selective sorption was observed for these sorbates, which bespeaks a pore size greater than about 0.5 nm. The sorption capacity of S2 was appreciably lower than that of zeolite X, Y, or mordenite. Routine sorption capacities were determined by a simple procedure of pore filling with benzene at room temperature after calcination of the samples at various temperatures. 

Effluent from each CFSTR was collected periodically in 7-mL scintillation vials filled with 5 mL of Beckman Ready Safe scintillation cocktail. The mass of effluent captured (approximately 0.5 mL) was quantified gravimetrically. The radioactivity of the samples was measured with a Packard Tri-Carb 1900CA liquid-scintillation analyzer, and the corresponding TCE concentrations were calculated with a standard curve relating concentration to counts per minute. The sampling periods lasted between 7 and 10 d. 

MOF-177 has been demonstrated to act like a super sponge in capturing vast quantities of carbon dioxide at room temperature. At moderate pressure (about 35 bar), its voluminous pores result in a gravimetric CO2 uptake capacity of 33.5 mmol/g, which far exceeds those of the benchmark adsorbents zeolite 13X (7.4 mmol/g at 32 bar) and activated carbon MAXSORB (25 mmol/g at 35 bar). In terms of volume capacity, a container filled with MOF-177 can hold about twice the amount of CO2 versus the benchmark materials, and 9 times the amount of CO2 stored in an empty container under the same conditions of temperature and pressure. 

Basic experiments were carried out with an extractor in analytical scale (SFE-703, DIONEX). For a typical experiment the extraction cells (10 ml internal volume) were fully filled with a homogeneous mixture of the flame retardent and the inert MgS04 and placed into the oven chamber of the extractor. After reaching the desired extraction conditions (pressures of 250 to 500 bar and temperatures of 60, 80 or 100 °C) the samples were extracted for 45 min. The extracted components were analysed by gravimetric, spectroscopic and/or chromatographic methods (IR, GC-MSD). Further experiments were made with realistic brominated ABS composites (granulated composites) in analytical scale and also with an extraction autoclave in laboratary scale (500 ml internal volume). 

Worked example 5.1 — soil water and air contents, and bulk density A soil core of 5 cm diameter and 8 cm height contains 257 g of fresh soil. After drying the soil at 110°C, the soil weighed 196 g. Calculate (i) the gravimetric soil water content, (ii) the volumetric soil water content, (iii) the soil bulk density, (iv) the % pore space, (v) the % water-filled pore space, and (vi) the % air-filled pore space. 

Figures 3 through 6 show conversion-time data for a number of vinyl acetate runs. The start-up procedure for these experiments consisted of filling the reaction vessel with degassed water prior to introducing any feed streams. Periodic samples were taken and the monomer conversion measured gravimetrically. As can be seen, some of the conversion transients did not reach a steady state. Tendency toward unsteady behavior and the magnitude of the oscillations seemed to increase with increasing initiator concentration and mean residence time. The influence of changing the emulsifier concentration is not clear.

Figure 4 >> bOd wirh sample vials, weighing btxiles, hygrometer, and Petri dishes filled wiltl anhydrous phosphorus pemmide for sample preparation for gravimetric mois luve teSL. 

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