Novel nano-reinforced chitosan derivatives for adsorption of heavy metal ions from aqueous media

Abstract

Abstract A novel NH 2 -MIL-53(Al)@CS-EDTA hybrid nanocomposite was synthesized by functionalizing chitosan with EDTA and integrating it with an Al-based MOF for heavy metal removal. Structural and morphological characterizations were performed using FT-IR, XRD, SEM-EDX, N2 adsorption-desorption isotherms, point of zero charge (PZC), and thermogravimetric analysis (TGA). Batch experiments showed maximum adsorption capacities of 31.8, 28.1, and 21 mg·g − 1 for Cu 2+ , Fe 2+ , and Ni 2+ at pH 6. The adsorption data were best fitted by the Langmuir isotherm and the pseudo-second-order kinetic model under the investigated experimental conditions. The observed adsorption behavior is proposed to involve coordination and electrostatic interactions between the metal ions and the abundant functional groups (–OH, –NH₂, and –COOH) of the composite. The biopolymer MOF composite’s reusability was also evaluated, and even after five consecutive adsorption-desorption cycles, > 90% efficiency was found, indicating acceptable stability over repeated cycles. The novelty of this study lies in the synergistic integration of biopolymer, chelating agent, and MOF into a single, reusable adsorbent with improved properties.