A Porous Organic Polymer Nanotrap for Efficient Extraction of Palladium

Abstract

To offset the environmental impact of platinum-group element (PGE) mining, recycling techniques are being explored. Porous organic polymers (POPs) have shown significant promise owing to their selectivity and ability to withstand harsh conditions. A series of pyridine-based POP nanotraps, POP-Py, POP-pNH₂ -Py, and POP-oNH₂ -Py, have been designed and systematically explored for the capture of palladium, one of the most utilized PGEs. All of the POP nanotraps demonstrated record uptakes and rapid capture, with the amino group shown to be vital in improving performance. Further testing on the POP nanotrap regeneration and selectivity found that POP-oNH₂ -Py outperformed POP-pNH₂ -Py. Single-crystal X-ray analysis indicated that POP-oNH₂ -Py provided a stronger complex compared to POP-pNH₂ -Py owing to the intramolecular hydrogen bonding between the amino group and coordinated chlorine molecules. These results demonstrate how slight modifications to adsorbents can maximize their performance.

Keywords: enhanced binding affinity; hydrogen bond stabilization; palladium recovery; platinum group elements; porous organic polymers.