Efficient, Selective, and Rapid Recovery of Gold from Highly Acidic Solutions Using an Ionic Phosphine-Functionalized Triptycene-Based Porous Organic Polymer

Developing a strategic material for efficient recovery of gold species from acidic waste is a highly important research topic. Extracting gold present in discarded electronic waste (e-waste) is a sustainable tactic to recycle the precious yellow metal to meet the growing demand for it. An economically viable recovery of significant amounts of gold from e-waste would have added environmental benefits, such as removing pollutants from contaminated water. In this study, we have synthesized a triptycene-based and triphenyl phosphine-modified porous organic polymer (TP-iPOP-PPh3) with an exceptional ability to extract gold from highly acidic solutions. The maximum gold adsorption capacity of TP-iPOP-PPh3 reached 1390 mg/g. The kinetics of adsorption followed the pseudo-second-order kinetic model. The Langmuir model best described the adsorption mechanism, suggesting efficient ion exchange and strong supramolecular (ion–dipole) interactions between the phosphorus centers and the tetrachloroaurate ions. TP-iPOP-PPh3 also demonstrated rapid and efficient gold extraction, capturing 99% of the gold species in only 5 min under harsh acidic conditions. The observed gold capture kinetics is, in fact, faster than that reported for several other gold adsorbents. In addition, the gold removal efficiency remained unaffected by other competing/interfering ions. These results underscore the potential of TP-iPOP-PPh3 as an adsorbent for extracting tetrachloroaurate ions dissolved in acidic solutions. Thus, TP-iPOP-PPh3 may contribute to both resource conservation/management and environmental protection by recovering gold from acidic waste and e-waste in a sustainable manner.