Cellulose-based MnO₂ nanocomposites for the efficient adsorption of copper (II) ions from aqueous solutions

In this study, cellulose-based nanocomposite adsorbents (Cell@MnO₂) were synthesized from valorized lignocellulosic biomass via a facile in situ precipitation and grafting process for the efficient removal of Cu²⁺ ions from aqueous solutions. Structural and physicochemical properties were characterized employed Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), point of zero charge (pH_pzc), and thermogravimetric analysis (TGA) coupled with its derivative (DTG). Batch adsorption experiments examined the effects of contact time, pH, dosage, concentration, and temperature. The materials exhibited rapid uptake kinetics, attaining equilibrium within 60 min and achieving a maximum removal efficiency of 99.58%, were well described by the Sips isotherm model, yielding a maximum adsorption capacity (q_max) of 351 mg g^-1. Thermodynamic analysis parameters indicated a feasible, spontaneous, and endothermic adsorption process, as evidenced by the positive values of enthalpy (ΔH) and entropy (ΔS) and the negative values of Gibbs free energy (ΔG). These findings demonstrate that the sustainable Cell@MnO₂ nanocomposites constitute efficient, low-cost, and environmentally friendly sorbents the remediation of copper-contaminated industrial effluents.