Metal framework functionalized with nitro groups and chitosan composite adsorption of Congo red

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Dye pollution poses a significant environmental challenge, with traditional adsorbents exhibiting limitations in efficiency and reusability.
• Metal-Organic Frameworks (MOFs) offer excellent properties but are hindered by their powdered form for practical wastewater applications.
• Developing effective and easily separable adsorbents is crucial for tackling dye contamination.

Purpose of the Study:

• To synthesize a novel nitro-functionalized MIL-88B (MIL-88B-NO2) material.
• To fabricate MIL-88B-NO2/Chitosan (CS) aerogels for enhanced dye adsorption.
• To investigate the adsorption performance, mechanism, and reusability of the developed aerogel for Congo Red (CR) dye removal.

Main Methods:

• MIL-88B was functionalized with nitro groups to create MIL-88B-NO2, significantly increasing its surface area.
• MIL-88B-NO2 was combined with chitosan to form a MIL-88B-NO2/CS aerogel, facilitating easy separation.
• Adsorption experiments were conducted to determine the capacity, kinetics, and mechanism for Congo Red removal.

Main Results:

• The MIL-88B-NO2 material exhibited a specific surface area of 660.98 m²/g, an 80% enhancement over pristine MIL-88B.
• The MIL-88B-NO2/CS aerogel achieved a maximum adsorption capacity of 878.8 mg/g for Congo Red.
• Adsorption followed pseudo-second-order kinetics and the Sips model, driven by π-π conjugation, electrostatic attraction, and hydrogen bonding.

Conclusions:

• The MIL-88B-NO2/CS aerogel is a highly efficient and reusable adsorbent for Congo Red dye removal.
• The aerogel structure overcomes the separation challenges associated with traditional MOF powders.
• This material shows significant potential for practical applications in treating dye-polluted wastewater.