https://cyberleninka.org/article/n/999493.pdf

New trends in removing heavy metals from industrial wastewater

Heavy metal removal from aqueous solution by advanced carbon nanotubes: Critical review of adsorption applications

In the study of adsorption, changes in free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) have been most frequently calculated from the Langmuir equilibrium constant. In a strict theoretical sense, the Langmuir equilibrium constant with units of liters per mole and the thermodynamic equilibrium constant without units are not the same. Moreover, the equilibrium constants for thermodynamic calculation have also been derived in different ways in the literature, for example, Frumkin isotherm, Flory−Huggins isotherm, distribution constants, and so on. As a result, values of ΔG°, ΔH°, and ΔS° of adsorption reported in the literature are very confusing. This study shows that for a dilute solution of charged adsorbates or for a solution of uncharged adsorbates at any concentration, the thermodynamic equilibrium constant of adsorption would be reasonably approximated by the Langmuir equilibrium constant, and thus the use of the Langmuir equilibrium constant for calculation of ΔG° and subsequent determination of ...

Is the Free Energy Change of Adsorption Correctly Calculated

Comparisons of low-cost adsorbents for treating wastewaters laden with heavy metals.

The Langmuir and Freundlich isotherm equations have been widely used for interpreting various adsorption processes. There are, however, many serious mistakes in the literature in determination or calculation of thermodynamic parameters, especially in the determination of the change in the free energy of adsorption using Langmuir, Freundlich and Henry constants. Many authors used these constants for the determination of ∆G expressed instead of dimensionless in some concentration units (for example: l mol-1, l g-1, ml mg-1, etc.).

/pdf/a-consideration-of-the-correct-calculation-of-thermodynamic-258tr62njw.pdf

S. Sebti

Papers

Removal of heavy metal ions from water by using calcined phosphate as a new adsorbent.

Removal of lead from aqueous solutions by activated phosphate.

Removal of Cadmium from Water Using Natural Phosphate as Adsorbent

Removal of lead from aqueous solutions by natural phosphate