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Supercritical Adsorption
Supercritical adsorption also referred to as the adsorption of supercritical fluids, is the adsorption at above-critical temperatures. There are different tacit understandings of supercritical fluids. For example, “a fluid is considered to be ‘supercritical’ when its temperature and pressure exceed the temperature and pressure at the critical point”. In the studies of supercritical extraction, however, “supercritical fluid” is applied for a narrow temperature region of 1-1.2T_ or T_ to T_+10 K, which is called the supercritical region. (T_ is the critical temperature) History Observations of supercritical adsorption reported before 1930 was covered in studies by McBain and Britton. All of the important articles on this subject published between 1930 and 1966 have been reviewed by Menon. During the last 20 years, a growing interest in supercritical adsorption research under the impetus of the quest for clean alternative fuels has been observed. Considerable progress ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a fluid (the ''absorbate'') is dissolved by or permeates a liquid or solid (the ''absorbent''). Adsorption is a '' surface phenomenon'', while absorption involves the whole volume of the material, although adsorption does often precede absorption. The term '' sorption'' encompasses both processes, while '' desorption'' is the reverse of it. Like surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are fulfilled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adsorbate
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a fluid (the ''absorbate'') is dissolved by or permeates a liquid or solid (the ''absorbent''). Adsorption is a ''surface phenomenon'', while absorption involves the whole volume of the material, although adsorption does often precede absorption. The term ''sorption'' encompasses both processes, while ''desorption'' is the reverse of it. Like surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are fulfilled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Adsorption Figure5
Supercritical may refer to: Physics and technology Condensed matter physics * Critical temperature, TC, a temperature above which distinct liquid and gas phases do not exist for a given material ** Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying ** Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: *** Supercritical carbon dioxide: **** Supercritical fluid chromatography, a form of liquid chromatography using supercritical carbon dioxide as the mobile phase ***Supercritical water: **** Supercritical steam generator, a steam generator operating above the critical point of water, hence having no water–steam separation **** Supercritical water oxidation or SCWO, a process that occurs in water at temperatures and pressures above a mixture's thermodynamic critical point **** Supercritical water reactor (SCWR), a Generation IV nuclear reactor concept that uses supercritical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Adsorption Figure4
Supercritical may refer to: Physics and technology Condensed matter physics * Critical temperature, TC, a temperature above which distinct liquid and gas phases do not exist for a given material ** Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying ** Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: *** Supercritical carbon dioxide: **** Supercritical fluid chromatography, a form of liquid chromatography using supercritical carbon dioxide as the mobile phase ***Supercritical water: **** Supercritical steam generator, a steam generator operating above the critical point of water, hence having no water–steam separation **** Supercritical water oxidation or SCWO, a process that occurs in water at temperatures and pressures above a mixture's thermodynamic critical point **** Supercritical water reactor (SCWR), a Generation IV nuclear reactor concept that uses supercritical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Adsorption Figure3
Supercritical may refer to: Physics and technology Condensed matter physics * Critical temperature, TC, a temperature above which distinct liquid and gas phases do not exist for a given material ** Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying ** Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: *** Supercritical carbon dioxide: **** Supercritical fluid chromatography, a form of liquid chromatography using supercritical carbon dioxide as the mobile phase ***Supercritical water: **** Supercritical steam generator, a steam generator operating above the critical point of water, hence having no water–steam separation **** Supercritical water oxidation or SCWO, a process that occurs in water at temperatures and pressures above a mixture's thermodynamic critical point **** Supercritical water reactor (SCWR), a Generation IV nuclear reactor concept that uses supercritical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Adsorption Figure2
Supercritical may refer to: Physics and technology Condensed matter physics * Critical temperature, TC, a temperature above which distinct liquid and gas phases do not exist for a given material ** Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying ** Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: *** Supercritical carbon dioxide: **** Supercritical fluid chromatography, a form of liquid chromatography using supercritical carbon dioxide as the mobile phase ***Supercritical water: **** Supercritical steam generator, a steam generator operating above the critical point of water, hence having no water–steam separation **** Supercritical water oxidation or SCWO, a process that occurs in water at temperatures and pressures above a mixture's thermodynamic critical point **** Supercritical water reactor (SCWR), a Generation IV nuclear reactor concept that uses supercritical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Adsorption Figure1
Supercritical may refer to: Physics and technology Condensed matter physics * Critical temperature, TC, a temperature above which distinct liquid and gas phases do not exist for a given material ** Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying ** Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: *** Supercritical carbon dioxide: **** Supercritical fluid chromatography, a form of liquid chromatography using supercritical carbon dioxide as the mobile phase ***Supercritical water: **** Supercritical steam generator, a steam generator operating above the critical point of water, hence having no water–steam separation **** Supercritical water oxidation or SCWO, a process that occurs in water at temperatures and pressures above a mixture's thermodynamic critical point **** Supercritical water reactor (SCWR), a Generation IV nuclear reactor concept that uses supercritical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condensation
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition. Initiation Condensation is initiated by the formation of atomic/molecular clusters of that species within its gaseous volume—like rain drop or snow flake formation within clouds—or at the contact between such gaseous phase and a liquid or solid surface. In clouds, this can be catalyzed by water-nucleating proteins, produced by atmospheric microbes, which are capable of binding gaseous or liquid water molecules. Reversibility scenarios A few distinct reversibility scenarios emerge here with respect to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica Gel
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum. In the last case, the material is properly called silica xerogel. Silica xerogel with an average pore size of 2.4 nanometers has a strong affinity for water molecules and is widely used as a desiccant. It is hard and translucent, but considerably softer than massive silica glass or quartz; and remains hard when saturated with water. Silica xerogel is usually commercialized as coarse granules or beads, a few millimeters in diameter. Some grains may contain small amounts of indicator substance that changes color when they have absorbed some water. Small paper envelopes containing silica xerogel pellets, usually with a "do not eat" warning, are often included in dry food packages to absorb any h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercritical Fluid
A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point (chemistry), critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can Effusion, effuse through porous solids like a gas, overcoming the mass transfer limitations that slow liquid transport through such materials. SCF are much superior to gases in their ability to Solvation, dissolve materials like liquids or solids. Also, near the critical point, small changes in pressure or temperature result in large changes in density, allowing many properties of a supercritical fluid to be "fine-tuned". Supercritical fluids occur in the atmospheres of the gas giants Jupiter and Saturn, the terrestrial planet Venus, and probably in those of the ice giants Uranus and Neptune. Supercritical water is found on Earth, such as the water issuing from black smokers, a type of underwater hydrothermal vent. They are used as a sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoporous Material
A mesoporous material (or super nanoporous ) is a nanoporous material containing pores with diameters between 2 and 50 nm, according to IUPAC nomenclature. For comparison, IUPAC defines microporous material as a material having pores smaller than 2 nm in diameter and macroporous material as a material having pores larger than 50 nm in diameter. Typical mesoporous materials include some kinds of silica and alumina that have similarly-sized mesopores. Mesoporous oxides of niobium, tantalum, titanium, zirconium, cerium and tin have also been reported. However, the flagship of mesoporous materials is mesoporous carbon, which has direct applications in energy storage devices. Mesoporous carbon has porosity within the mesopore range and this significantly increases the specific surface area. Another very common mesoporous material is activated carbon which is typically composed of a carbon framework with both mesoporosity and microporosity depending on the condition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activated Carbon
Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area available for adsorption (which is not the same as absorption) or chemical reactions. Activation is analogous to making popcorn from dried corn kernels: popcorn is light, fluffy, and has a surface area that is much larger than the kernels. ''Activated'' is sometimes replaced by ''active''. Due to its high degree of microporosity, one gram of activated carbon has a surface area in excess of as determined by gas adsorption. Charcoal, before activation, has a specific surface area in the range of . An activation level sufficient for useful application may be obtained solely from high surface area. Further chemical treatment often enhances adsorption properties. Activated carbon is usually derived from waste products such as coconut husks; waste f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
