What is adsorption isotherm graph?
An adsorption isotherm is a graph that represents the variation in the amount of adsorbate(x) adsorbed on the surface of the adsorbent with the change in pressure at a constant temperature.
What is ion exchange adsorption?
The adsorption results in the formation of a molecular layer of the adsorbate on the surface. Often an equilibrium concentration is rapidly formed on the surface and is sometimes followed by a slow diffusion into the particles of the adsorbent. Ion exchange is an exchange of ions between a liquid and a solid phase.
What is a Langmuir plot?
The Langmuir adsorption isotherm is used to describe the equilibrium between adsorbate and adsorbent system, where the adsorbate adsorption is limited to one molecular layer at or before a relative pressure of unity is reached.
What is RL in Langmuir isotherm?
RL = 1 / 1+KLCo (5) Where C0 (mg/L) is the initial dye concentration and KL (L/mg) is the Langmuir constant related to the energy of adsorption. The value of RL indicates the shape of the isotherms to be either unfavourable (RL > 1), linear (RL = 1), favourable (0 < RL <1) or irreversible (RL = 0).
What is KF in Freundlich isotherm?
ions adsorbed at equilibrium (mg g−1); KF is the Freundlich adsorption capacity; 1/n is the sorption. constant having a value range between 0 and 1. The linear form of the Temkin isotherm is reported as: qe = BTln(KTCe)
What is the purpose of isotherm?
isotherm, line drawn on a map or chart joining points with the same temperature. Isotherms are commonly used in meteorology to show the distribution of temperature at the Earth’s surface or on a chart indicating constant level or constant pressure.
What is ion exchange equilibrium?
Ion exchange is an adsorption process which occurs when there is equilibrium between a fixed number of ions on the resin phase and ions in solution. The concentrations in the solution and resin phases can be expressed in the form of mole fractions.
Is ion exchange adsorption or absorption?
Along with absorption and adsorption, ion exchange is a form of sorption. Ion exchange is a reversible process, and the ion exchanger can be regenerated or loaded with desirable ions by washing with an excess of these ions.
What is the difference between Langmuir isotherm and Freundlich isotherm?
The major difference between these two models is that Langmuir assumes that ions are adsorbed as a monolayer on the surface, and the maximum adsorption occurs when the surface is completely covered, whereas Freundlich has assumptions of heterogeneous surfaces with different affinities that have multilayer adsorption.
What is the difference between the Freundlich and Langmuir adsorption isotherms?
The key difference between Freundlich and Langmuir adsorption isotherms is that Freundlich adsorption isotherm is empirical, whereas Langmuir adsorption isotherm is theoretical. The adsorption isotherm is a primary method that we can use to predict the adsorption capacity of a particular substance.
How do you calculate KF in Freundlich isotherm?
The units of KF from Freundlich isotherm are (mg/g)*(L/mg)^1/n and not unitless or L/g or mg/g as expressed in many manuscripts. there is only one case that gives you the sorption capacity (not the maximum adsorption capacity) which is when the solution concetration is 1 mg/L.
What is Temkin isotherm?
The Temkin isotherm model assumes that the adsorption heat of all molecules decreases linearly with the increase in coverage of the adsorbent surface, and that adsorption is characterized by a uniform distribution of binding energies, up to a maximum binding energy. The Temkin isotherm can be described by Equation (5).
What is the difference between ion exchange and adsorption isotherms?
The motivation of the application of the adsorption isotherms is that both ion adsorption and exchange result in the increase of surface excess concentration of the ions. However, in case of ion adsorption, the net charge of the surface changes, while in case of ion exchange this remains constant.
What is an isotherm model in ion exchange chromatography?
CPA model for the adsorption of proteins within an ion exchange column as a function of ionic strength and pH. The SMA isotherm is a common model for ion exchange chromatography (IEC) using multi-point binding, the influence of counter-ions, and displacement.
What type of adsorption isotherm explains the formation of multilayer?
This isotherm explains the formation of multilayer. There is no flattish portion in the curve which indicates that monolayer formation is missing. Examples of Type III Adsorption Isotherm are Bromine (Br 2) at 790°C on silica gel or Iodine (I 2) at 790°C on silica gel. At lower pressure region of graph is quite similar to Type II.
What is the coefficient of linear adsorption isotherm?
Accordingly, the coefficient of the linear adsorption isotherm is k d = 0.17 0.0982 = 1.731 lb hexane / lb solid lb hexane / cuft gas. Use the Hougen–Marshall chart ( Fig. 15.13 ): Z ′ = k g a Z u s = 206.4 ( 3.58) 11.4 = 64.82, Values of τ are read off Figure 15.13 and converted into values of t:
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