Synthesis and Characterization of MO:ZnO/Fe₂O₃ Nanocomposite and Its Effectiveness in the Degradation of Green Malachite Dye: Molecular Dynamics and Electronic Properties Study of Green Malachite Adsorption

Abstract

Nanocomposites have attracted significant attention from researchers due to their remarkable chemical, adsorptive, and thermal properties. This work focuses on the synthesis of the montmorillonite modified with octadecylamine (MO):ZnO/Fe2O3 (MO:ZnO/Fe2O3) nanocomposite. The ZnO/Fe2O3 nanocomposite and MO were mixed in solution to create the component. XRD, FTIR, BET, TEM, MEB, and UV–vis were used to characterize the materials. In terms of their textural, morphological, and structural characteristics, interesting results were found. After 30 min of sunlight exposure, 96.12% of the GM dye can be degraded using just 0,02 g of MO:ZnO/Fe2O3 (1:2(1/0.05)). In contrast, ZnO NPs exhibited the highest percentage of degradation under UV light, achieving 91.85%. The greater efficiency of MO:ZnO/Fe2O3 under sunlight is attributed to its narrower band gap of 2.25 eV, which enables better utilization of visible light. Next using the Forcite and CASTEP modules in the Material Studio software, the GM dye’s adsorption behavior on the surface of the as-prepared nanocomposite was analyzed. The results demonstrate that the GM/MO interaction is of the chemisorption type, predominantly governed by hydrogen bonding, electrostatic interactions, and π–π interactions between GM molecules. The ZnO (100) surface exhibits the highest density of active sites for GM degradation via a chemisorption adsorption process. Molecular dynamics simulations at 289.15 K reveal that the redox processes responsible for the degradation of the GM pollutant and its conversion into CO2 gas are exothermic. For ZnO, the electronic properties yield a band gap of 2.686 eV. For GM/ZnO (100) and GM/ZnO (101), the band gaps were determined to be 0.291 and 2.704 eV, respectively, by using a 340 eV cutoff energy and the GGA RPBE pseudofunctional.