Glucuronoxylan-based quince seed mucilage for efficient Ni(II) removal: Isotherm, kinetic, and thermodynamic insights

Quince seed mucilage (QSM), a novel and eco-friendly bioadsorbent, was assessed for abstracting nickel ions from water via parametric optimization (initial metal ion concentration, contact time, mucilage dosage, pH, and temperature), isotherm, kinetic, and thermodynamic analyses. The optimum concentration (500 ppm) and mucilage dose (60 mg) showed favourable adsorption with a maximum contact time of 30 min at 45 °C and pH 7. Characterization of QSM using FTIR, XRD, SEM, and EDX confirmed the involvement of -OH and -COOH groups in Ni(II) binding, as indicated by peak shifts and surface morphological changes. Adsorption equilibrium data were best fitted to the Freundlich isotherm model (R² = 0.98, n = 1.75), followed by the pseudo-second-order model (R² = 0.99), and positive ΔH° (34.45 kJ/mol) and ΔS° (128.84 J/mol.K) values, and a negative ΔG° (-3.95 to -7.17 kJ/mol) at all studied temperatures. Future research should focus on regeneration mechanisms, multi-metal adsorption systems, and pilot-scale applications to validate industrial feasibility.