Uptake Capacity

An as-prepared aerogel sample was placed in an organic solvent until it was completely soaked with the liquid. The uptake capacity of the aerogel sample was then quantified in terms of the mass of the organic liquid absorbed per unit mass (1 g) of the aerogel sample. Table 4.6 contains a list of sorption capacities for various common hydrocarbons. 

---

At constant alkalinity, the ocean can absorb more C02 by replacing one [CO2, ] with two [HCO3]. Because 90% of all the inorganic C02 in the ocean is in the form of [HCO3], the uptake capacity of the ocean is far less than the 39,000 GtC present in the ocean. Eliminating all carbonate ions would reduce the pH to about 4 and store no more than 3500 GtC. In equilibrium with 550 ppm of C02 in the air, the pH of the ocean would drop by 0.3 and if stirred into the entire ocean, it could pick up about 1000-1500 GtC. Without active interference, the approach to this equilibrium would take millennia (Lackner, 2002). 

From the above it can be said that MOF-5 s density goes from around 0.3 g cm"3 (packing density) up to a maximum value of 0.59 g cm 3 (crystal density), giving values of volumetric uptake capacity at 77 K and 4 MPa from 15.6 g L 1 up to 30.6 g L 1. The more realistic value of volumetric uptake capacity (15.6 g L 1) obtained using the MOF s packing density is lower than those obtained in the present study for powder activated carbons, as one can see in Figure 5. 

FIGURE 4.2 Effects of Viscozyme L on water uptaking capacity of psyllium. 0, 2.4, 4.8, 9.6,19.2, and 36 represent the final Viscozyme L concentrations of 0,2.4,4.8,9.6,19.2, and 36 units/g of psyllium in the solid-state reactions, respectively. Means are reported and the vertical bars represent the standard deviation of each data point (n = 3). (Adapted from Yu et al, 2003). 

The initial decrease in ocean uptake rate will eventually be reversed once enough time has passed (millennia) for meridional overturning circulation to recycle the subsurface waters. This will serve to inject CO2 below the mixed layer. Once the surface waters have been sufficiently acidified and are transported into the deep sea, they will eventually start dissolving sedimentary calcium carbonate. The resupply of alkalinity via this route will provide sufficient enhancement to ocean carbon uptake capacity to... 

Collection of the phosphate-stripped activated sludge, which has extremely high phosphorus uptake capacity from the stripper. 

Monolayer coverage of vanadium oxide on tin oxide support was determined by a simple method of low temperature oxygen chemisorption and was supported by solid-state NMR and ESR techniques. These results clearly indicate the completion of a monolayer formation at about 3.2 wt.% V2O5 on tin oxide support (30 m g" surface area). The oxygen uptake capacity of the catalysts directly correlates with their catalytic activity for the partial oxidation of methanol confirming that the sites responsible for oxygen chemisorption and oxidation activity are one and the same. The monolayer catalysts are the best partial oxidation catalysts. 

The effect of chemisorption temperature on the ammonia uptake capacity of 6.5 wt% V20c/Ti02 is shown in Fig. 1. Ammonia chemisorption capacities increase with temperature upto 150°C and then decrease with further Increase up to 400°C. It is worth noting that there is considerable NH uptake even at 400°C. These results are in accordance with the reported literature. A number of studies have been reported on the acidic character of supported transition-metal oxides (22,34-38). Ammonia on V20g can be either adsorbed in the form of NH species on Bronsted acid sites or coordlnatively bonded to vanadium ions on Lewis acid sites (39,40). The latter species were observed up to 250°C,... 

Figure 1. Effect of temperature on ammonia uptake capacity of 6.5 wt.% V20g/Ti02(A)...

Another approach to improving access to the catalyst interior and, therefore, the metal uptake capacity is to modify the catalyst shape, which can decrease the effective diffusion length without compromise on reactor... 

The conjugation of vitamin B12 has been shown to increase oral bioavailability of peptides, proteins, and particles.44 46 62,63 Russsell-Jones and coworkers have attempted to exploit RME of vitamin B12 for the enhanced intestinal uptake of macromolecules such as luteinizing hormone—releasing factor (LHRH), granulocyte colony-stimulating factor, erythropoietin, and a-interferon.44,46,63 Also, they demonstrated that surface modification of nanoparticles with vitamin B12 can increase their intestinal uptake.44,62 The extended applications of this unique transport system, however, appear partially hampered by its limited uptake capacity. In human being, the uptake of vitamin B12 is only 1 nmol per intestinal passage. 

The ammonia uptake capacity is rather low. Even after reactions at 1473 K for 17h, less than 25% N incorporation is obtained. 

When the silica gel is treated with trichlorosilane, prior to the ammoniation, the ammonia uptake capacity is enhanced with a factor 5-10. This enhancement is effective in the entire reaction temperature region. The room temperature... 

The observations that (1) the ammonia uptake capacity is exactly the two-fold of the initial Cl-concentration (2) the chlorine groups remain on the surface after ammoniation at room temperature and (3) the infrared spectrum shows intense bands, assigned to NH4+ and Si-NH2 species, lead to following reaction mechanism (I) ... 

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. 

Peckol, P, DeMeo-Anderson, B., Rivers, J., Valiela, I., Maldonado, M., and Yates, J. (1994). Growth, nutrient uptake capacities and tissue constituents of the macroalgae, Cladophora vagabunda and Gracilaria tikvahiae, related to site-specific nitrogen loading rates. Mar. Biol. 121, 175-185. 

Transport of metals in the environment is critically dependent on speciation. Often metals are associated with colloidal materials, fulvic acid, or humic acid. Extensive research is ongoing to study the uptake capacity of these materials as well as minerals, the distribution of elements in natural water samples, and species-dependent means of remediation. Speciation of yttrium and lanthanides in natural water has been reported [415] using size exclusion chromatography and ICP-MS. Multistage filtration has also been used with ICP-MS measurement of the separated fractions [416]. Kinetic studies of metal uptake rate as a function of EDTA, NTA, and fulvic acid concentrations in the water have been described [417]. 

Increased hydrogen release could exceed the uptake capacity of hydrogen by micro-oiganisms in the soil, currently the main way in which hydrogen is removed from the atmosphere. The result would be that hydrogen concentrations in the atmosphere would increase more rapidly, which would reinforce the consequences described above. 

---