Biosorption Mechanism of Aqueous Pb²⁺, Cd²⁺, and Ni²⁺ Ions on Extracellular Polymeric Substances (EPS)

Table 1

Thermodynamic and kinetics models of heavy metals adsorption on EPS.

Models	Formula	Model parameters
Langmuir adsorption isothermal model		——the initial concentration of heavy metals (mg L^-1); ——the unit adsorption capacity when the initial concentration is Ce (mg g^-1); ——maximum unit adsorption capacity (mg g^-1); ——Langmuir adsorption equilibrium constant (L mg^-1)
Freundlich adsorption isothermal model		——adsorption capacity (mg g^-1); ——Freundlich adsorption capacity
Dubinin–Radushkevich adsorption isothermal model		——equilibrium adsorption capacity (mg g^-1); ——maximum unit adsorption capacity (mg g^-1); ——constant related to adsorption capacity (mol^2/kJ^2)
		——ideal gas constant (); ——thermodynamic temperature; ——initial concentration of contaminants (mg L^-1); Average adsorption energy
Pseudo-first order kinetics model		——adsorption time (min); ——unit adsorption capacity after t min (mg g^-1); ——the maximum unit adsorption capacity (mg g^-1); ——pseudo-first-order reaction rate constant
Pseudo-second order kinetics model		——pseudo-second-order reaction rate constant