Phase Rule
... representing the isothermal variation of adsorption of a quantity of gas adsorbed by unit mass of solid adsorbent with pressure. This equation is known as Freundlich Adsorption Isotherm or Freundlich Adsorption equation or simply Freundlich Isotherm.X/M=KP • Where x is the mass of the gas adsorbed o ...
... representing the isothermal variation of adsorption of a quantity of gas adsorbed by unit mass of solid adsorbent with pressure. This equation is known as Freundlich Adsorption Isotherm or Freundlich Adsorption equation or simply Freundlich Isotherm.X/M=KP • Where x is the mass of the gas adsorbed o ...
Document
... If (DH) ads is very large for a given situation, it is clear that catalysis will be hindered precisely because that species is too tenaciously held at the surface. If, on the other hand, (DH) ads is very low , the species in question may not be desorbed on the catalyst surface for a time l ...
... If (DH) ads is very large for a given situation, it is clear that catalysis will be hindered precisely because that species is too tenaciously held at the surface. If, on the other hand, (DH) ads is very low , the species in question may not be desorbed on the catalyst surface for a time l ...
Donnan phenomena in membranes with charge due to ion
... interaction, and Eq. (7) reduces to the well-known Langmuir adsorption isotherm13,14 with adsorption constant K. Adsorption isotherms having the dependence on the fractional surface occupation given by Eq. (7) are known as Frumkin isotherms in the electrical double layer literature.15 More refined t ...
... interaction, and Eq. (7) reduces to the well-known Langmuir adsorption isotherm13,14 with adsorption constant K. Adsorption isotherms having the dependence on the fractional surface occupation given by Eq. (7) are known as Frumkin isotherms in the electrical double layer literature.15 More refined t ...
Characterization of nanopores by standard enthalpy and entropy of
... The characterization of a porous material starts with the determination of the pore volume and the pore size distribution. Pores less than 2 nm in size are called micropores for the adsorption of diatomics or simple polyatomic molecules with molecular diameters in the range 0.3–0.5 nm (here the word ...
... The characterization of a porous material starts with the determination of the pore volume and the pore size distribution. Pores less than 2 nm in size are called micropores for the adsorption of diatomics or simple polyatomic molecules with molecular diameters in the range 0.3–0.5 nm (here the word ...
สอบปลายภาค - SWU Course Syllabus
... Using statistical thermodynamics Mean energies and the equipartition principle Heat capacities Residual entropy Ortho- and Para- hydrogen General expression for the partition function The equilibrium constant in terms of the partition functions ตัวอย่ำงกำรคำนวณ และแบบฝึ กหัด ...
... Using statistical thermodynamics Mean energies and the equipartition principle Heat capacities Residual entropy Ortho- and Para- hydrogen General expression for the partition function The equilibrium constant in terms of the partition functions ตัวอย่ำงกำรคำนวณ และแบบฝึ กหัด ...
Functionalizing spin-textured surfaces with tailored organic bonds
... of molecule-TI interaction, the surface of the TI can be passivated, the Dirac point can energetically be shifted at will, and Rashba-split quantum-well interface states can be created [2]. In the case of the Pb-Ag alloy, we have studied the influence of specific chemical bonds - as formed by the or ...
... of molecule-TI interaction, the surface of the TI can be passivated, the Dirac point can energetically be shifted at will, and Rashba-split quantum-well interface states can be created [2]. In the case of the Pb-Ag alloy, we have studied the influence of specific chemical bonds - as formed by the or ...
Catalyst Notes - University of Idaho
... The table below gives the pre-exponential constant and the activation energy for steps 2, 3, and 4. The 'sticking coefficient' S in the table is a convenient way to specify the reaction rate constant for adsorption. S is the probability that a process (reaction, adsorption, desorption) occurs when a ...
... The table below gives the pre-exponential constant and the activation energy for steps 2, 3, and 4. The 'sticking coefficient' S in the table is a convenient way to specify the reaction rate constant for adsorption. S is the probability that a process (reaction, adsorption, desorption) occurs when a ...
Energetics of adsorption of neutral and charged molecules at the air
... producing pulses of 5 ps duration was used. For some of the experiments, the dye laser was amplified to 10-15 ,uJ pulse energy at 10 KHz repetition rate by means of a 20 W copper vapor laser. The input beam was focused into the liquid sample at an angle of 70” from the normal to the surface. The ref ...
... producing pulses of 5 ps duration was used. For some of the experiments, the dye laser was amplified to 10-15 ,uJ pulse energy at 10 KHz repetition rate by means of a 20 W copper vapor laser. The input beam was focused into the liquid sample at an angle of 70” from the normal to the surface. The ref ...
Unit XI Laboratory work № 11 Physical chemistry Questions: Surface
... concentration increase, the absolute quantity of adsorbed molecules grows, although the percentage adsorbed is lower than at low concentration. Shifts of equilibrium due to changes in temperature are governed by the fact that adsorption is accompanies by the liberation of heat. Therefore, according ...
... concentration increase, the absolute quantity of adsorbed molecules grows, although the percentage adsorbed is lower than at low concentration. Shifts of equilibrium due to changes in temperature are governed by the fact that adsorption is accompanies by the liberation of heat. Therefore, according ...
Surface chemistry and Catalysis
... Freundlich Adsorption Isotherm A graph between the amount (x/m) adsorbed by an adsorbent and the equilibrium pressure of the adsorbate at constant temperature is called adsorption isotherm At low pressure graph is nearly a straight line. x/m = kpn x/m is the amount of gas adsorbed k and n are const ...
... Freundlich Adsorption Isotherm A graph between the amount (x/m) adsorbed by an adsorbent and the equilibrium pressure of the adsorbate at constant temperature is called adsorption isotherm At low pressure graph is nearly a straight line. x/m = kpn x/m is the amount of gas adsorbed k and n are const ...
Derivation of the BET and Langmuir Isotherms
... Atkins, P.W. Physical Chemistry 2nd edition. San Francisco: W. H. Freeman and Company, 1978. Atkins, P.W. Physical Chemistry 6th edition. San Francisco: W. H. Freeman and Company, 1998. Derivation of the Langmuir and BET Isotherms ...
... Atkins, P.W. Physical Chemistry 2nd edition. San Francisco: W. H. Freeman and Company, 1978. Atkins, P.W. Physical Chemistry 6th edition. San Francisco: W. H. Freeman and Company, 1998. Derivation of the Langmuir and BET Isotherms ...
O 95: Metal Substrates: Adsorption of Atoms and Inorganic Molecules
... Methanol" from CO2 /H2 as a "Solar Fuel", suitable also for the specific operation conditions resulting from that application[1]. Previously, CuZn alloys have been used as model systems for the industrially used Cu/ZnO catalysts[2]. For Au/ZnO this approach is similarly plausible. In order to gain m ...
... Methanol" from CO2 /H2 as a "Solar Fuel", suitable also for the specific operation conditions resulting from that application[1]. Previously, CuZn alloys have been used as model systems for the industrially used Cu/ZnO catalysts[2]. For Au/ZnO this approach is similarly plausible. In order to gain m ...
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) permeates or is dissolved by a liquid or solid (the absorbent). Adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of it. Adsorption is a surface phenomenon.Similar to 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 filled 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 bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.Adsorption is present in many natural, physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increase storage capacity of carbide-derived carbons, and water purification. Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Pharmaceutical industry applications, which use adsorption as a means to prolong neurological exposure to specific drugs or parts thereof, are lesser known.However, it should be remarked that the distinction between adsorption and absorption vanishes as we go from perfectly crystalline macroscopic materials to porous/structured materials, aggregates and composites made out of increasingly smaller grains, viz., micron-sized particles to nanoparticles, sub-nano particles and finally molecules (or atoms). In such nano-composites, the internal surface area of particulate matter is very large. Then the adsorption on internal surfaces simply becomes absorption when viewed from the bulk. Then the distinction between adsorption and absorption vanishes. On the other hand, the distinction is clearest between bulk solids without internal structure, but having only surfaces where only adsorption can occur on the outer surfaces, and nanocomposites or aggregates with internal structure where absorption by the host material is simply adsorption on internal surfaces of the host material. As an example, we may consider a crystalline piece of silicon dioxide (quartz) which can adsorb water molecules on its surface. However, if the quartz is ground into very fine sand, the pile of sand (an aggregate) has a very large internal surface area. A very large amount of water can be adsorbed by the ""internal"" surfaces of the grains in the pile of sand, and this absorption is simply ""internal adsorption. If water is made to flow thorugh such a pile of sand, ions and toxins in the water may be preferentially adsorbed by the surfaces of the grains of sand, providing a simple, well-known water purification application.The word ""adsorption"" was coined in 1881 by German physicist Heinrich Kayser (1853-1940).