Ultra-stable, low-cost mussel-inspired coating functionalized polypropylene nonwoven fabrics based on a double crosslinking strategy and their efficient palladium (II) recovery performance

Palladium, a strategic precious metal with important applications in electronics, chemical and pharmaceutical fields, but its natural reserves are scarce and expensive, efficient recovery technology has become a key issue in the field of resource recycling. This study developed an in situ double cross-linking strategy to hance the stability of mussel-inspired coatings, and amino-functionalized adsorbent (PP-TEPA) was successfully constructed, which made a breakthrough in cost control and stability. The mussel-inspired coatings were formed by rapid deposition in the presence of oxidizing agents, catechol and tetraethylenepentamine (TEPA) and were significantly enhanced by in situ cross-linking of glutaraldehyde (GA) and ethylene glycol diglycidyl ether (EGDE) to form a three-dimensional cross-linked structure. PP-TEPA exhibits exceptional stability (20 days in organic solvents, acids and bases) and achieves breakthrough cost control ($40/kg). It demonstrates high Pd (II) adsorption capacity (226.79 mg/g), outstanding selectivity (separation factor > 10,000), salt resistance, ultrafast desorption (99 % efficiency in 1 min), and excellent reusability. The application of PP-TEPA for the recovery of palladium from real pharmaceutical wastewater was demonstrated. This work reveals the adsorption behavior and adsorption mechanism of Pd (II) on PP-TEPA for precious metal recovery.