Sorbent effect on the sorption of Cr(VI) on a Mg6AlFe-layered double hydroxide and its calcined product in aqueous solutions

Sorption of Pb(II) on carboxymethyl chitosan-conjugated magnetite nanoparticles: application of sorbent dosage-dependent isotherms

“…In our previous work [17,[19][20][21][22], an exponential form of the C s -dependent function of f s was suggested as follows:…”

“…Figure 6 also shows that Γ e decreases with increasing C s at any given pH, C NaNO3 , or T. This suggests that under the different conditions studied, the C s -effect exists in the sorption equilibria. For a given C 0 , there is a relationship between Γ e and C s as follows [17]:…”

“…The γ value can indicate the strength of the C s -effect for a sorption system and a higher γ value represents a stronger C s -effect. In addition, the relationships between the intrinsic parameters in the SCA model equations and the corresponding parameters in the classical Langmuir and Freundlich isotherms were obtained as follows [17,[19][20][21][22]:…”

“…Because both classical isotherms are thermodynamic equilibrium equations [8], their model parameters should be independent of both the sorbate and sorbent concentrations for a given system under a constant temperature, pressure, and medium composition (e.g., pH and ionic strength) [9]. However, several studies [10][11][12][13][14][15][16][17][18][19] have reported that the parameters of the two classical models simulated using experimental data vary with the sorbent dose (C s ). This phenomenon is known as the sorbent effect (C seffect) [10].…”

“…The parameters of the two SCA model equations are C s independent. Our previous work showed that the SCA model could describe C s -dependent sorption in some systems [16][17][18][19]. However, there remains an urgent need to further examine the general applicability of the SCA model in describing the sorption equilibria with the C s -effect.…”