Carboxymethyl-imidazolium O-vanillin Schiff base grafted into NH₂-tagged MIL-101 (Cr) for effective removal of cupric ions from aqueous effluents

A novel adsorbent (MIL-CMIVSB) was fabricated by modification of H₂N-MIL-101(Cr) with carboxymethyl-imidazolium O-vanillin Schiff base. The MIL-CMIVSB’s physicochemical characteristics were examined using the pertinent characterization methods. NH₂-MIL-101(Cr) has a BET surface area of 1492.4 m²g⁻¹, while MIL-CMIVSB adsorbent had 1278.7 m²g⁻¹. Batch adsorption experiments examined the MIL-CMIVSB’s cupric ion adsorption capacity from aqueous solutions at different adsorbent doses (0.1–3 mg), pH (2.0–10.0), contact times (0–240 min), metal ion initial concentrations (10–300 mg/L), and temperatures (298–308 K). The optimum conditions were 1 mg/mL of MIL-CMIVSB adsorbent, 46 min adsorption time, pH 7, 100 ppm initial cupric ion concentration, and 303 K temperature. MIL-CMIVSB effectively and selectively removes cupric ions with an adsorption capability of 359.05 ± 12.06 mg/g. The nonlinear Liu isotherm governed Cu(II) sorption performance on MIL-CMIVSB (K_L = 0.257 ± 0.01 mg/g, R² = 0.99892) and pseudo-2nd-order kinetically (k₂ = 0.00116 × 10⁻⁴ g/mg min, R² = 0.99721).