What is elovich equation?
THE equation first proposed by Roginsky and Zeldovich1 but now generally known as the Elovich equation has been extensively applied to chemisorption data2,3. The equation is where q = amount of gas chemisorbed at time t and a and α are constants.
What is elovich model?
2.3 Elovich model This model helps to predict the mass and surface diffusion, activation and deactivation energy of a system. Although the model was initially applied in gaseous systems, its applicability in wastewater processes has been redeemed meaningful.
What is pseudo second order reaction?
pseudo-second order reaction means the reactions in which one parameter is thought to be constant among the three parameter dependent reactions.
What is intraparticle diffusion model?
The intraparticle diffusion model (IPD) proposed by Weber and Morris has been widely applied for the analysis of adsorption kinetics. In this work, the characteristic curves based on this model were plotted with various initial adsorption factors (Ri).
What are adsorption kinetics?
Adsorption kinetics is the measure of the adsorption uptake with respect to time at a constant pressure or concentration and is employed to measure the diffusion of adsorbate in the pores. From: Activated Carbon Fiber and Textiles, 2017.
What is adsorption mechanism?
In the adsorption mechanism, two gaseous reactants are adsorbed through two independent reactions. Then the two surface intermediates interact and a gaseous product is released. The general form of this mechanism can be represented as. (7.116)
What is the difference between pseudo first order and first order?
Difference Between Pseudo First Order Reaction and First Order Reaction. The main difference is obviously that, in a first order reaction, the order of reaction is one by nature. A pseudo first-order reaction is second order reaction by nature but has been altered to make it a first order reaction.
What is the difference between pseudo first and second order?
In addition to what has been said, all it means is that, for Pseudo first order, only one reactant is a determining step in the rate of a reaction. In second order, both reactants participate in a reaction.
What is self diffusion coefficient?
According to IUPAC definition, self-diffusion coefficient is the diffusion coefficient of species when the chemical potential gradient equals zero. It is linked to the diffusion coefficient.
What is adsorption theory?
The adsorption theory states that adhesion results from molecular contact between two materials and the surface forces that develop. A bond develops from the adsorption of adhesive molecules on the substrate and the resulting attractive forces, usually designated as secondary or van der Waals forces.
How do you calculate adsorption in kinetics?
ce/qe = 1/qm KL + ce/qm , where ce is the equilibrium concentration of the adsorbate and qe is the adsorption capacity adsorbed at equilibrium, qm is maximum adsorption capacity and KL is the Langmuir adsorption constant.
What is the difference between adsorbate and adsorbent?
Adsorbate refers to the molecular species that gets adsorbed on the surface, whereas adsorbent refers to the surface on which adsorption happens. Clay, silica gel, colloids, metals, and other adsorbents are common examples.
What is the Elovich equation?
An Elovich-type equation has been used to describe the interactions of gas molecules with heterogeneous surface sites on the sorbent, accounting for the change in activation energy of desorption as a function of the surface coverage.
Is the Elovich equation of a nonuniform surface uniform?
It is shown that the familiar, simple model of a nonuniform surface does, in fact, lead to a rate equation in good agreement with the Elovich equation at very short as well as at very long times. The model gives a physical significance to the constant t0 and, when t0 is appreciable, leads to Elovich plots having two linear sections.
Does the rate of adsorption on a heterogeneous surface agree with Elovich’s equation?
Earlier treatments of the rate of adsorption on a heterogeneous surface have given results which do not agree with the Elovich equation at very short times.
Why does the Elovich plot have two linear sections?
The model gives a physical significance to the constant t0 and, when t0 is appreciable, leads to Elovich plots having two linear sections. Similar experimental plots can be found.