Hydrazone-Linked Covalent Organic Framework Catalyst via Efficient Pd Recovery from Wastewater

Global consumption and discharge of palladium (Pd) have
raised
environmental concerns but also present an opportunity for the sustainable
recovery and reuse of this precious metal. Adsorption has proven to
be an efficient method for the selective recovery of Pd from industrial
wastewater. This study investigated a hydrazone-linked covalent organic
framework (Tfpa-Od COF) as a potential material for the
high-affinity adsorption of Pd2+ ions from wastewater,
achieving a Kd value of 3.62 × 106 mL g–1. The electron-rich backbone of the
COF contributes to its excellent selective removal efficiency (up
to 100%) and adsorption capacity of 372.59 mg g–1. Furthermore, the Pd-adsorbed COF was evaluated as a sustainable
catalyst for the Suzuki–Miyaura coupling reaction, demonstrating
good catalytic conversion and recyclability. This work attempts to
showcase a protocol for reusing waste palladium generated in water
to fabricate heterogeneous catalysts and, thereby, promote the circular
economy concept.