Experiments and Mechanisms of Modified Metal-organic Framework Materials for Remediation of Vanadium-chromium Combined Pollution in Water

The co-contamination of V(Ⅴ) and Cr(Ⅵ) in wastewater poses significant risks to aquatic ecosystems and human health. However, it remains challenging to both develop efficient adsorbents for their simultaneous removal and elucidate their interactions. In this study, a novel metal-organic framework (MOFs) adsorbent, UiO-66-NH₂, was synthesized in an open system at atmospheric pressure for the treatment of combined pollution of V(Ⅴ) and Cr(Ⅵ) in solution. Adsorption experiments demonstrated that UiO-66-NH 2 exhibits strong adsorption capacity toward V(V) and Cr(VI), primarily governed by chemisorption. The maximum adsorption capacities for V(V) and Cr(VI) in single system adsorption were 543.40 mg/g and 335.28 mg/g, respectively. In the binary system, V(V) and Cr(VI) adsorption capacities reached 712 mg/g and 501 mg/g, respectively, which were 1.92 and 3.32 times those in their respective single systems. This confirms synergistic effects. However, localized uptake fluctuations, such as a 4.4% decrease in Cr uptake with increasing V concentration, indicate competitive interactions. The material also showed selective adsorption toward V(V). Combined with material characterization and molecular dynamics (MD) simulations, the chemical composition and structural stability of the material were analyzed, and the adsorption mechanism at the micro level was revealed. The adsorption mechanism of UiO-66-NH 2 for V(V) and Cr(VI) involves electrostatic interactions, chemical reduction, hydrogen bonding, and coordination. These findings provide theoretical insights for the application of UiO-66-NH 2 in treating V(V) and Cr(VI) contaminants in wastewater and for the design of related adsorbents.