Selective Dye Adsorption by Zeolitic Imidazolate Framework-8 Loaded UiO-66-NH₂

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Wastewater treatment requires efficient methods for dye removal.
• Metal-Organic Frameworks (MOFs) offer tunable properties for adsorption.
• UiO-66-NH2 and ZIF-8 are promising MOFs for pollutant remediation.

Purpose of the Study:

• To synthesize and characterize ZIF-8-loaded UiO-66-NH2 for dye removal.
• To investigate the selective adsorption of anionic and cationic dyes.
• To evaluate the adsorption capacity, kinetics, thermodynamics, and reusability of the composite.

Main Methods:

• Synthesis of ZIF-8-loaded UiO-66-NH2.
• Characterization of the composite material.
• Adsorption experiments with methyl orange, methylene blue, and rhodamine B.
• Kinetics, isotherm, and thermodynamic analyses.
• Reusability tests over four adsorption cycles.

Main Results:

• ZIF-8-loaded UiO-66-NH2 exhibited superior selectivity for methylene blue (MB) compared to parent MOFs.
• Adsorption capacity for MB was 173 mg/g, a 215% increase over UiO-66-NH2.
• Adsorption followed pseudo-second-order kinetics and Langmuir isotherm, indicating a spontaneous exothermic physical process.
• The composite maintained significant regeneration efficiency for MB adsorption after four cycles.

Conclusions:

• ZIF-8-loaded UiO-66-NH2 is a highly effective adsorbent for cationic dyes like MB.
• The enhanced performance is attributed to electrostatic interactions and π-π stacking.
• The material demonstrates excellent reusability, making it a sustainable solution for dye wastewater treatment.