(a) Langmuir isotherm model
Langmuir isotherm is based on the following assumptions: (a) each surface site can be singly occupied, (b) there are no lateral interactions between adsorbed species, (c) the enthalpy of adsorption is independent of surface coverage and (d) energy of adsorption is constant. The Langmuir isotherm is 2.5
Where Qm is the maximum adsorption for a …show more content…
The Freundlich constant ‘n’ indicates the degree of favourability of adsorption and its value should be lying in the range of 1 to 10 for favourable adsorption. A smaller value of (1/n) indicates a stronger bond between adsorbate and adsorbent, while a higher value for Kf indicates higher rate of adsorption.
2.5.5.2. Adsorption kinetics
Most of the adsorption/desorption transformation processes of various solid phases are time dependent. To understand the dynamic interactions of pollutants with solid phases and to predict their fate with time, knowledge of the kinetics of these processes is important. Various kinetic models have been used, whereas in this study the pseudo-first-order and pseudo-second-order models were studied.
(a) Pseudo-First Order Model
Pseudo-first order equation or Lagergren's kinetics equation is widely used for the adsorption of an adsorbate from an aqueous solution (Lagergren, 1898). 2.9 After integration and applying boundary conditions t=0 to t= t and qt = 0 to qt=qt, the integrated form of equation becomes,
Langmuir isotherm is based on the following assumptions: (a) each surface site can be singly occupied, (b) there are no lateral interactions between adsorbed species, (c) the enthalpy of adsorption is independent of surface coverage and (d) energy of adsorption is constant. The Langmuir isotherm is 2.5
Where Qm is the maximum adsorption for a …show more content…
The Freundlich constant ‘n’ indicates the degree of favourability of adsorption and its value should be lying in the range of 1 to 10 for favourable adsorption. A smaller value of (1/n) indicates a stronger bond between adsorbate and adsorbent, while a higher value for Kf indicates higher rate of adsorption.
2.5.5.2. Adsorption kinetics
Most of the adsorption/desorption transformation processes of various solid phases are time dependent. To understand the dynamic interactions of pollutants with solid phases and to predict their fate with time, knowledge of the kinetics of these processes is important. Various kinetic models have been used, whereas in this study the pseudo-first-order and pseudo-second-order models were studied.
(a) Pseudo-First Order Model
Pseudo-first order equation or Lagergren's kinetics equation is widely used for the adsorption of an adsorbate from an aqueous solution (Lagergren, 1898). 2.9 After integration and applying boundary conditions t=0 to t= t and qt = 0 to qt=qt, the integrated form of equation becomes,