Rapid Removal of Cr(VI) from Wastewater by Surface Ionized Iron-Based MOF: Ion Branching and Domain-Limiting Effects.

Exploring the ratio of metal centers to organic ligands and the amount of DMF are important to improve the stability and adsorption efficiency of MOF materials as adsorbents. In this work, MIL101(Fe)-Na₂CO₃ was successfully obtained by modification with formic acid, sodium carbonate, carbon nanotubes, and moieties. The adsorption efficiency of MIL-101(Fe) on Cr(VI) was greatly improved, and the removal efficiency was able to reach 100% in 20 min with a maximum adsorption capacity of 20 mg/g. The inhibition order of the competing anions for the removal of hexavalent chromium was as follows: Cl⁻ < NO₃⁻ < SO₄²⁻. The analysis of the adsorption thermodynamic model found that the adsorption of MIL101(Fe)-Na₂CO₃ for Cr(VI) showed spontaneous heat-absorbing and entropy-increasing chemisorption behavior. When using NaOH as the eluent and HCl as the regeneration stabilizer, MIL-101(Fe)-Na₂CO₃ had good adsorption capacity in multiple cycles. [ABSTRACT FROM AUTHOR]