Strengthening adsorptive amelioration: Isotherm modeling in liquid phase surface complexation of Pb (II) and Cd (II) ions

The mitigation of recalcitrant heavy metals in an economic fashion is still a headline issue even though various methodologies and techniques have been explored. In this present study, inexpensive and abundant Eucalyptus (Eucalyptus globulus) bark has been utilized for adsorbent development; AdsEbc for mitigation of Pb (II) and Cd (II) ions from aqueous phase successfully. AdsEbc showed promising adsorption capacity of 26.12 and 35.65 mg g− 1 for Pb (II) and Cd (II) ions at pH 5 and 8, respectively, calculated by best fitted isotherm modeling. Thermodynamics results revealed the feasibility and endothermic nature of adsorption process. Langmuir, Freundlich, Langmuir–Freundlich (Sips), Redlich–Peterson (R–P) and Dubinin–Radushkevich (D–R) models were used for the mathematical description of the relationship between adsorbed and aqueous concentration of adsorbate on adsorbent surfaces at equilibrium. Spectroscopic examinations of adsorbent were carried out with scanning electron microscopy and Fourier transform infrared spectroscopy.

Research Highlights
► Adsorption of recalcitrant heavy metals with promising adsorption capacity.
► Different isotherm models and statistical investigation of the relationship between adsorbate and adsorbent surfaces at equilibrium.
► Different kinetic models for Pb (II) and Cd (II) adsorption.
► Thermodynamic significance of isotherm finding.