A Study on the Synergistic Adsorption Performance of ZIF-8/HKUST-1 Nanocomposite for La³⁺ Ions

In this study, ZIF-8/HKUST-1 and ZIF-67/HKUST-1 composite materials were fabricated via a stepwise solvent-assisted synthesis route. The materials were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and N₂ physisorption (BET). The La³⁺ adsorption performance was systematically evaluated through batch experiments under varying pH, contact time, initial concentration, and temperature. The experimental data were fitted to kinetic, isotherm, and thermodynamic models to elucidate the underlying adsorption mechanism. ZIF-8/HKUST-1 showed the best performance for La³⁺ adsorption using a pH of 6. Under this condition, adsorption equilibrium was attained in just 30 min, and the maximum adsorption capacity reached 250.72 mg/g. The composite also maintained 81.25% of its initial capacity after five adsorption-desorption cycles. This excellent retention rate attests to its structural stability and reusability, pointing to a strong potential for industrial use.