Zeolitic Imidazole Framework Decorated Substrates for Lead Removal From Water

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Lead contamination in water poses significant health risks.
• Zeolitic imidazole frameworks (ZIFs) are effective adsorbents for heavy metals.
• ZIF-67's susceptibility to hydrolysis can limit its application in water remediation.

Purpose of the Study:

• To compare the hydrolytic stability and Pb²⁺ adsorption of ZIF-8 and ZIF-67.
• To investigate the effect of substrate anchoring on ZIF stability and lead adsorption.
• To elucidate the mechanisms of adsorption and hydrolysis in ZIFs.

Main Methods:

• Systematic comparison of ZIF-8 and ZIF-67 under controlled pH.
• Integration of adsorption capacity measurements, kinetic analysis, and metal-node leaching.
• Structural characterization using advanced techniques.
• Coordination of ZIF-67 with Mucor hiemalis membranes.

Main Results:

• ZIF-67 exhibits higher hydrolytic sensitivity than ZIF-8.
• Substrate anchoring with Mucor membranes significantly reduced Co²⁺ leaching and improved structural retention of ZIF-67.
• Optimized ZIF-67@Mucor achieved a high Pb²⁺ adsorption capacity of 867 mg g^-1 at pH 5.
• Distinguished ion exchange from framework degradation during metal uptake.

Conclusions:

• Substrate-dependent stabilization is crucial for enhancing the hydrolytic stability of ZIFs.
• Modified ZIF-67@Mucor offers a promising and stable adsorbent for efficient lead removal from aqueous solutions.
• This study provides a mechanistic understanding for utilizing ZIFs in water remediation.