Stable Acrylamide-Linked Covalent Organic Frameworks via Mannich Polymerization for Efficient Gold Recovery from...

Area of Science:

• Materials Science
• Chemistry
• Environmental Science

Background:

• Covalent organic frameworks (COFs) are crucial for resource recovery but often lack stability and selectivity.
• Efficient gold recovery from complex matrices like electronic waste remains a significant challenge.

Purpose of the Study:

• To develop novel acrylamide-linked COFs with improved stability and selectivity for Au3+ capture.
• To investigate the structure-property relationships governing COF performance in metal recovery.

Main Methods:

• One-step Mannich-type three-component polymerization of 1,3,5-triformylbenzene, Meldrum's acid, and aromatic diamines.
• Characterization of COF crystallinity, porosity, and stability under harsh conditions.
• Evaluation of selective Au3+ binding using dual coordination sites (C═O and N─H) via hydrogen bonding and chelation.

Main Results:

• A series of stable acrylamide-linked COFs (TFB-PD-M, TFB-ND-M, TFB-AD-M) were synthesized with enhanced π-conjugation and backbone rigidity.
• The COFs exhibited high crystallinity, permanent porosity, and exceptional chemical/thermal stability.
• TFB-AD-M achieved 98.5% selective Au3+ recovery from electronic waste leachates, outperforming competing metal ions.

Conclusions:

• Acrylamide linkages provide a robust strategy to enhance COF stability and functionality.
• The developed COFs are highly effective for selective gold recovery, offering a sustainable solution for electronic waste recycling.