There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

Application of low-cost adsorbents for dye removal – A review

Since the time of the industrial revolution, the atmospheric CO(2) concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO(2) emissions are necessary. Large emission point sources, such as fossil-fuel-based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO(2) from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less-energy-intensive separation technology. This Review describes the CO(2) adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic-inorganic hybrids, and metal-organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO(2) capacities as well as other important parameters such as adsorption-desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO(2) adsorbents and their critical properties that will ultimately affect their incorporation into large-scale separation processes is presented.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

https://persianmof.weebly.com/uploads/4/8/8/3/48832931/chem._rev._2014,_114,_10575.pdf

Water stability and adsorption in metal-organic frameworks.

Rebreather-type personal protective equipment requires efficient removal of CO2 from the air that the user exhales. The required operating conditions of low CO2 partial pressure, low temperature, and water saturation create a challenging environment for developing high capacity CO2 adsorbents. Biphasic adsorbents of lithium hydroxide supported on high surface area carbons were synthesized and tested for CO2 capacity under water-saturated conditions. The LiOH phase provides high CO2 capacity through chemisorption while the porous carbon structure helps prevent the formation of diffusion barriers that limit the effectiveness of pure LiOH pellets. Several carbons with different pore morphology were tested, and it was determined that the ideal support has a high degree of mesoporosity that balances the need for high surface area without excess blockage of pore volume upon deposition of LiOH. The activated carbon Norit SX Ultra was chosen based on this criterion. It was found that the maximum achievable loading of LiOH on Norit SX Ultra was 30 wt%, and the highest CO2 capacity under water-saturated conditions at atmospheric pressure with one mole percent CO2 in the gas phase was 3.4 mol/kg.

Supported lithium hydroxide for carbon dioxide adsorption in water-saturated environments

Mise au point d'une relation decrivant la concentration pour un profil a parametre constant, quels que soient les profils de vitesse a symetrie axiale, les isothermes et les coefficients de partage; le transfert de matiere etant decrit par la diffusion radiale et axiale. Pour les ecoulements de Poiseuille, pour les grands coefficients de partage et les grands nombres de Peclet, obtention d'une solution analytique, sous forme d'equation integrale basee sur les series de Graetz, pour l'allure des profils constants. La solution est evaluee pour les isothermes de Langmuir et Freundlich. Les nombres de Scherwood locaux calcules a partir des resultats sont dependants du parametre isotherme et de la position axiale

Constant-pattern behavior for adsorption on the wall of a cylindrical channel

Adsorbent filters often use activated carbons to remove a wide range of toxic chemicals from air. It is of interest to know if filter performance for these compounds can be diffusion limited as a r...

110th Anniversary: Molecular Structure Effects on Mass Transfer of C10 Hydrocarbons in BPL Activated Carbon

The accessible pore space for Lennard-Jones gas molecules adsorbed in smooth-walled carbon nanopores in the Henrys law region is determined for slit-shaped, cylindrical, and spherical pores. The size of this space, over which the total potential is nonpositive, depends on pore geometry and number of wall layers. Pores with small surface mean curvature are more accessible than those with larger surface mean curvature. Adding layers to the wall helps to increase the accessible pore space, but this effect is small after the second layer. Limits are determined for the smallest pores having accessible space. For the slit-shaped pore with a single wall, the minimum pore half width is the same as the width of the inaccessible layer at the wall of a single graphene sheet, which is less than the Lennard-Jones solid-fluid collision diameter. In contrast, the minimum radius of a spherical pore with accessible space is the Lennard-Jones solid-fluid collision diameter.

Accessible volumes for adsorption in carbon nanopores of different geometries and wall thicknesses

Good quality adsorbent fabrics were electrospun from slurries of zirconium hydroxide nanoparticles and polyvinyl butyral (PVB) in alcohols. The as-spun fabrics had very high porosity, about 80 vol%, and high zirconium hydroxide content, 50–95 wt%. The porosity and mechanical strength of the fabrics could be modified via compaction and/or exposure to alcohol vapor. SO2 sorption capacity of the fabrics was high at 1.6–1.9 mol/kg and was relatively independent of the sample pretreatment, unlike the capacity of the pristine nanoparticles, which decreased when the powder was stored in a low relative humidity atmosphere. The as-purchased zirconium hydroxide nanoparticles contained about 45 wt% of water, equivalent to the formula ZrO2·5.6H2O. In contrast, the electrospun composite fabrics contained only 25 wt% of mostly coordinated water, leading to the formula ZrO2·2.2H2O. The presence of PVB binder inhibited the rehydration/dehydration processes and stabilized the SO2 sorption capacity of the composite fibers. The electrospun fabrics could find applications as conformable, flexible filters in civilian and military applications.

M. Douglas LeVan

Papers

Supported lithium hydroxide for carbon dioxide adsorption in water-saturated environments

Constant-pattern behavior for adsorption on the wall of a cylindrical channel

110th Anniversary: Molecular Structure Effects on Mass Transfer of C10 Hydrocarbons in BPL Activated Carbon

Accessible volumes for adsorption in carbon nanopores of different geometries and wall thicknesses

Electrospun zirconium hydroxide nanoparticle fabrics as sorptive/reactive media