Development of a novel MIL‐68‐NH₂@MCC composite for enhanced and synergistic removal of methylene blue and Sm(III) from an aqueous environment

Abstract

In this study, a pioneering composite material, MIL‐68‐NH2@MCC, was synthesized by integrating an indium‐based metal–organic framework (MIL‐68‐NH2) with microcrystalline cellulose (MCC), that could be prepared by recycling different natural products of cellulose. The surface characteristics of the novel MIL‐68‐NH2@MCC composite were meticulously examined through X‐ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDX). Remarkably, MIL‐68‐ NH2@MCC demonstrated significantly improved efficiency in removing methylene blue (MB) dye and Sm(III) ions from aqueous solutions, surpassing the removal capabilities of its individual constituents, MIL‐68‐NH2 and MCC. This superior performance can be attributed to the synergistic interplay between MIL‐68‐ NH2 and MCC. We thoroughly investigated the influence of various parameters, including pH, contact time, initial concentration, and temperature. The experimental adsorption data for both MB and Sm(III) exhibited a good fit with the Langmuir isotherm model. The optimized MIL‐68‐NH2@MCC exhibited remarkable maximum adsorption capacities of 133.8 mg/g for MB and 72.1 mg/g for Sm(III). The adsorption kinetics followed a pseudo‐second‐order model with correlation coefficients of 0.9879 and 0.9875 for MB and Sm(III), respectively. The application of intraparticle diffusion and the Boyd kinetic models demonstrated that the film diffusion is the dominant factor influencing the rate of the adsorption process. The study also examined a possible mechanism for the adsorption of MB and Sm(III) on the optimized MIL‐68‐NH2@MCC surface. Ultimately, the results highlight the originality of our research in terms of the efficacy of the newly developed MIL‐68‐NH2@MCC composite as an eco‐friendly adsorbent. Besides, the developed adsorbent effectively removes MB and Sm(III) from different water solutions while exhibiting outstanding selectivity and reusability.