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

Abstract

<title>Abstract</title> Due to the widespread presence of copper-containing contaminants, it is crucial to explore novel effective approaches to scavenging Cu(II) from potable water. To that end, a novel adsorbent (MIL-CMIVSB) was successfully fabricated by modification of H₂N-MIL-101(Cr) with carboxymethyl-imidazolium <italic>O</italic>-vanillin Schiff base. The MIL-CMIVSB's physicochemical characteristics were examined using the pertinent characterization methods. Batch adsorption tests were performed to determine the optimal conditions for MIL-CMIVSB's adsorption capacity for cupric ions in aqueous solutions. The optimum conditions are 1 mg/mL of MIL-CMIVSB adsorbent, 46 min adsorption time, pH 7, 100 ppm initial cupric ion concentration, and 303 K temperature. By integrating adsorption kinetics, adsorption isotherm, and Van't Hoff models, the adsorption behavior was interpreted. It was found that MIL-CMIVSB removed Cu(II) more selectively and effectively (adsorption capacity 359.05 ± 12.06 mg/g). The non-linear Liu isotherm governed Cu(II) sorption performance on MIL-CMIVSB (<italic>R</italic>² = 0.99892) and pseudo-2nd-order kinetically (<italic>R</italic>² = 0.99721).