Sorptive capacity

Material and uses Shape"of particles Size range, U.S. standard mesh f Internal porosity, % Bulk dry density, kg/L Average pore diameter, nm Surface area, kmVkg Sorptive capacity, kg/kg (dry)... 

Sorption. Capture of neutral organics by non-living particulates depends on the organic carbon content of the solids (9). Equilibrium sorption of such "hydrophobic" compounds can be described by a carbon-normalized partition coefficient on both a whole-sediment basis and by particle size classes. The success of the whole-sediment approach derives from the fact that most natural sediment organic matter falls in the "silt" or "fine" particle size fractions. So long as dissolved concentrations do not exceed 0.01 mM, linear isotherms (partition coefficients) can be used. At higher concentrations, the sorptive capacity of the solid can be exceeded, and a nonlinear Freundlich or Langmuir isotherm must be invoked. 

An alternative gas for ECBM is N2, which has a different enhanced recovery mechanism from C02. N2 is less sorptive than methane, with a sorptive capacity roughly 40% that of methane for high volatile bituminous B coal (Fig. 1). The N2 process works by reducing the partial pressure of methane in the secondary system, increasing the rate of desorption from the primary system, and the rate of methane diffusion through the primary system. Some N2 sorbs into the primary system but the majority remains in the secondary system. N2 also increases the... 

Samples, assuming they do not need to be ground, are at a minimum sieved through a number 10 sieve that has openings of 2 mm. This is done because the upper limit of sand, for consideration as part of soil, is 2 mm in average diameter. Components larger than this have a relatively low surface-to-volume ratio and very little sorptive capacity. Sieved samples can be further mixed and then divided into subsamples. 

The isotherms on silane-treated surfaces are different from one another, considering the precision of the method, but these differences are minor, and are not worthy of detailed analysis. The main inference from analysis of physical adsorption is that silane deposition mitigates the sorptive properties of glass substrates, which is in accord with results of previous work [2-5]. This trend also correlates with results from water thermodesorption, which demonstrate that water-sized glass has the highest sorptive capacity for water, while silane-treated samples exhibit diminished sorptive properties. 

Acid-base chemistry on a surface has the effect of changing the form of the surface bound species, instead of directly generating new volatile compounds. This can influence the overall sorptive capacity of indoor surfaces or even catalyze transformative reactions. Compound sorption influences the timing and intensity of exposure by temporarily storing these species on indoor surfaces (Tichenor et al., 1991 Won et al., 2001). For example, if a compound adsorbs strongly during an emission event, the peak concentration during the event will be lower than anticipated. However, desorption of those compounds will cause occupants to be exposed over an extended time period. 

The study of indoor organic chemistry improves our understanding of personal exposure to both reactants and products. At present, our ability to make predictions or estimate past exposure is rudimentary. To improve, we need a more comprehensive evaluation of the mechanisms, rates and mediating factors in indoor environments. For example, it is well established that humidity tends to enhance ozone uptake on indoor surfaces, but how does this influence product formation Do C02 or NH3 influence transformative product yields as well as influencing the sorptive capacity of surfaces To what extent do occupants contribute to this chemistry through their choice of products, smoking or cooking ... 

Pankow (1994a,b) proposed that gaseous POPs also absorb into a liquid-like organic film on the particles. Liang and Pankow (1996), and Pankow (1999) found the sorptive capacity of environmental tobacco smoke (almost entirely organic matter) and urban air particles (about 20% organic matter) for n-alkanes and PAHs was nearly the same when normalized to the organic content of the particles. Gas absorption is expressed by ... 

Usually, the solid adsorbent under investigation must first be freed, as far as possible from previously adsorbed gases and vapours. Evacuation to c. 10 4 Torr (outgassing) for several hours will usually remove physically adsorbed gas. It is difficult, and often impossible, to remove chemisorbed gas completely unless the solid is heated to a high temperature (c. 100-400°C). Such treatment might cause sintering and an alteration of the sorptive capacity of the solid. 

Selective Chemical Extraction, minerals, the interpretation of selective extraction data requires knowledge of the sorptive capacity of those minerals and their susceptibility to alteration during the course of experiments ... 

Neptunium and plutonium sorption behaviors were remarkably similar, implying that they had similar sorption reactions and solution species. Both NaOH and NaA102 decreased neptunium and plutonium sorption. Several explanations can be offered to rationalize this behavior. First, NaOH and NaAlO, may have reacted with the sediment minerals to yield solids of lower sorptive capacity. Aluminate ion, as an anionic species, also may have competed with the similar neptunate and plutonate anions for sorption sites. Finally, sodium hydroxide may have stabilized the hydrolyzed Np02(0H) and Pu02(0H)2" species in solution, as was shown in the solubility tests, and prevented sorption. Explanation of the effect of NaOH and NaA102 on neptunium and plutonium sorption will require further investigation. 

The washed fly ashes were observed to have a significant excess of sorptive capacity beyond that required to treat the element originally leached from the fly ash (see Table V ). 

Barrie (1968) collected all the known data on water sorption. From these data it is possible to estimate the effect of the different structural groups on water sorption at different degrees of humidity. Table 18.14 presents the best possible approach to the sorptive capacity of polymers versus water, i.e. the amount of water per structural group at equilibrium, expressed as molar ratio. From these data the solubility (cm3 water vapour (STP) per cm3 of polymer) can be easily calculated. (The multiplication factor is 22.4 x 103/V, where V is the molar volume per structural polymer unit.)... 

From Table 18.14, which gives data for amorphous polymers, it is evident that the sorptive capacity of the CH2 groups may be neglected. So what remains is two CONH groups per structural unit with a molar water content (at a relative humidity of 0.7) of 2 x 0.75 = 1.5 mole/structural unit. 

Sorptive capacity is one of the most important properties, and it has been investigated by many authors for several varieties of starch.331-333,335,419 Sair and Fetzer,420 and also Rakowski,331-333 compared the water-retention capacities of wheat, arrowroot, and potato starch, and the results were similar. Among the following starch varieties, the sorptive capacity decreases in the order given potato > arrowroot > wheat. The order potato > corn > wheat was reported by El-Khawas et al.42] Nara el a/.407 reported the order potato > tapioca > waxy rice > sweet potato > rice Smolina422 reported the orders potato > maize > rice > wheat at low humidity and potato > rice > maize > wheat at high humidity. These orders do not agree with the order reported in Table XVII on the effect of desiccation on the water retention of starch. Based on these data, the... 

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