Cadmium removal from aqueous solution using cellulose nanofibers obtained from waste sugarcane bagasse (SCB): isotherm, kinetic, and thermodynamic studies

The aim of this study was to investigate the adsorption of cadmium (Cd) from aqueous solutions using the cellulose nanofibers (CNF) obtained from sugarcane bagasse (SCB). The impact of operational parameters including pH, contact time, adsorbent dosage, and initial cadmium concentration were investigated according to the one-factor-at-a-time method. The results showed that the Cd removal (%) increased in the pH range of 3–5 and remained steady up to pH 6. The maximum adsorption efficiency (99.9%) was obtained at an adsorbent dosage of 4 g/L, pH = 5, Cd concentration of 5 mg/L, and equilibrium time of 70 min. In addition, Cd removal followed the Freundlich isotherm (R2 = 0.991 at 303°K) and pseudo-second-order kinetic model (R2 = 0.997). All ∆G° values were negative and the positive values of enthalpy change (∆H° = 66.76 kJ/mol), and entropy change (∆S° = 0.238 kJ/mol) showed that the adsorption process of Cd(II) was endothermic and spontaneous. With regards to the reliability and efficiency of CNF, this adsorbent is recommended for the removal of heavy metals such as Cd from an aqueous environment. © 2021 Desalination Publications. All rights reserved.