Nitrogen capacity determination

The equilibrium adsorption capacity for nitrogen was determined for each of the samples tested. Isotherms were measured in the range of 0.2 to 700 mmHg adsorbate gas pressure and at 22, 40 and 65 C. Due to the amount of data taken,... 

The equilibrium capacities of nitrogen and oxygen from air and the adsorbent capacities for pure nitrogen were determined for an 8-inch bed of each adsorbent contained in a l-1nch I.D. by 24-in. stainless steel tube. The packed bed was placed in a three-zone tube furnace. The adsorbents were activated under a flow of dry nitrogen and controlled temperature ramp, in a manner we previously found leaves a high proportion of the zeolite cations in a dehydroxylated state.(12)... 

Nitrogen capacities for pure gas were determined In a similar manner. Following activation, the adsorbent beds were allowed to equilibrate 1n a stream of dry nitrogen at 30°C. Thermal desorption coupled with void volume measurements by helium displacement into a gas buret at atmospheric pressure yielded the amount of nitrogen adsorbed. 

When the values of the BET monolayer capacity calculated from Type III isotherms are compared with independent estimates (e.g. from nitrogen adsorption) considerable discrepancies are frequently found. A number of typical examples are collected in Table 5.1. Comparison of the value of the monolayer capacity predicted by the BET equation with the corresponding value determined independently (columns (iv) and (v)) show that occasionally, as in line 6, the two agree reasonably well, but that in the majority... 

The relationship between the BET monolayer capacity of physically adsorbed water and the hydroxyl content of the surface of silica has been examined by Naono and his co-workers in a systematic study, following the earlier work by Morimoto. Samples of the starting material—a silica gel—were heated for 4 hours in vacuum at a succession of temperatures ranging from 25 to 1000°C, and the surface concentration of hydroxyl groups of each sample was obtained from the further loss on ignition at 1100°C combined with the BET-nitrogen area. Two complete water isotherms were determined at 20°C on each sample, and to ensure complete... 

The external surface area of the filler can be estimated from a psd by summing the area of all of the equivalent spheres. This method does not take into account the morphology of the surface. It usually yields low results which provide Htde information on the actual area of the filler that induences physical and chemical processes in compounded systems. In practice, surface area is usually determined (5) from the measured quantity of nitrogen gas that adsorbs in a monolayer at the particle surface according to the BET theory. From this monolayer capacity value the specific surface area can be determined (6), which is an area per unit mass, usually expressed in m /g. 

Nitrogen compounds commonly determined are creatinine, urea, and uric acid. Creatinine is an end product of the energy process occurring within the muscles, and is thus related to muscle mass. Creatinine in urine is commonly used as an indicator and correction factor of dilution in urine. Creatinine in serum is an indicator of the filtration capacity of the kidney. Urea is the end product of the nitrogen luea cycle, starting with carbon dioxide and ammonia, and is the bulk compoimd of urine. The production of uric acid is associated with the disease gout. In some cases, it appears that the excess of uric acid is a consequence of impaired renal excretion of this substance. 

Some properties of the rock used in this study were measured The cation exchange capacity (cec) was determined by the barium sulfate method as described by Mortland and Mellor (33). Surface area was measured by using a Digisorb Meter (Micromeritics Instrument Corporation) through nitrogen adsorption. Estimation of mineral composition and indentification of the rock were performed by X-ray diffraction. 

Functional property tests were conducted in duplicate. AACC (21) methods were used for the determination of water hydration capacity (Method 88-04) and nitrogen solubility index (NSI) (Method 46-23). Oil absorption capacity was measured by the procedures of Lin et al. (22) and oil emulsification by a modification (22) of the Inklaar and Fortuin (23) method. Pasting characteristics of 12.0% (w/v, db) slurries of the flours and processed products were determined on a Brabender Visco/Amylograph (Method 22-10). The slurries were heated from 30 to 95°C before cooling to 50°C to obtain the cold paste viscosity value. Gelation experiments were conducted by heating 15% (w/v db) slurries in sealed stainless steel containers to 90°C for 45 min in a water bath C3). 

A sample of the polymer to be studied and an inert reference material are heated and cooled in an inert environment (nitrogen) according to a defined schedule of temperatures (scanning or isothermal). The heat-flow measurements allow the determination of the temperature profile of the polymer, including melting, crystallization and glass transition temperatures, heat (enthalpy) of fusion and crystallization. DSC can also evaluate thermal stability, heat capacity, specific heat, crosslinking and reaction kinetics. 

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