Molecular simulation-based assessing of a novel metal-organic framework modified with alginate and chitosan biopolymers for anionic reactive black 5 and cationic crystal violet pollutants capture

Abstract

This study employed molecular simulations to develop efficient and environmentally friendly adsorbents for removing two common dye pollutants, crystal violet (CRVT) and reactive black 5 (RBC5). The investigated adsorbents are based on biodegradable polymers alginate (ALG) and chitosan (CHAN) functionalized with carboxyl acid groups (CA) on a UIO-66 metal–organic framework (MOF). Density functional theory (DFT) analyses such as electrostatics potential (ESP), Average local ionization energy (ALIE) analysis, COSMO-RS (Conductor-like Screening Model for Real Solvents) analysis and the density of states (DOS) were performed to investigate the structures of the pollutants and adsorbents. Physical and chemical properties of the adsorbents, including density, Hamiltonian energy (HAE), the radius of gyration (ROG), and the stress autocorrelation function (SACF) were also examined. Additionally, molecular dynamics (MD) and Monte Carlo (MC) simulations were employed to study the adsorption of CRVT and RBC5 onto CA/UIO-66, CA/UIO-66/ALG, and CA/UIO-66/CHAN adsorbents. The results demonstrated that functionalizing CA/UIO-66 with CHAN and ALG significantly enhances the adsorption capacity for both CRVT and RBC5. The modified adsorbent demonstrated significantly higher affinity towards RBC5 compared to CRVT, as evidenced by the adsorption energies of −1.11 × 104 kcal/mol for CA/UIO-66-CHAN-W-CRVT and −1.36 × 107 kcal/mol for CA/UIO-66-CHAN-W-RBC5. This research highlights the potential of CHAN- and ALG-functionalized CA/UIO-66-based adsorbents as promising alternatives to current wastewater treatment methods. These adsorbents are efficient, biodegradable, and environmentally friendly, offering remarkable potential for removing dye pollutants from industrial and domestic wastewater.