Functionalized Titanium-Based MOF for Cr(VI) Removal from Wastewater

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.
• Effective remediation strategies for Cr(VI) contamination are urgently needed.
• Metal-organic frameworks (MOFs) offer tunable properties for environmental applications.

Purpose of the Study:

• To develop a novel functionalized Ti-based MOF for enhanced Cr(VI) removal.
• To investigate the simultaneous adsorption and reduction of Cr(VI) to Cr(III).
• To evaluate the performance of the functionalized MOF under various conditions.

Main Methods:

• Functionalization of MIL-125(Ti)-NH2 with amidoxime groups to create MIL-125(Ti)-AO.
• Adsorption experiments to determine Cr(VI) adsorption capacity using Langmuir fitting.
• Systematic investigation of parameters including pH, contact time, initial Cr(VI) concentration, and interfering ions.
• Analysis of the synergistic adsorption mechanism involving [Ti-O] bonds and amidoxime groups.

Main Results:

• The functionalized MIL-125(Ti)-AO demonstrated a high Cr(VI) adsorption capacity of 271 mg·g⁻¹.
• Simultaneous reduction of Cr(VI) to Cr(III) was observed during the adsorption process.
• Residual chromium concentrations in treated water fell below the WHO recommended limit of 0.05 mg·L⁻¹.
• The material showed excellent performance across various experimental conditions and in the presence of competitive ions.

Conclusions:

• MIL-125(Ti)-AO is a highly effective adsorbent for Cr(VI) removal from aqueous solutions.
• The synergistic effect of adsorption and in-situ reduction by amidoxime groups is key to its performance.
• This novel MOF presents a promising solution for environmental remediation of chromium-contaminated water.