Improper Estimation of Thermodynamic Parameters in Adsorption Studies with Distribution Coefficient <i>K</i> <sub>D</sub> ( <i>q</i> <sub>e</sub> / <i>C</i> <sub>e</sub> ) or Freundlich Constant ( <i>K</i> <sub>F</sub> ): Considerations from the Derivation of Dimensionless Thermodynamic Equilibrium Constant and Suggestions