A mechanistic study of the efficient adsorption for platinum(IV) by amino-functionalized calix[4]arene

Efficient platinum extraction is essential for the sustainable advancement of industries reliant on platinum. This study introduces a novel approach for the selective adsorption of platinum. The amino-functionalized calix[4]arene, 5,11,17,23-tetra-tert-butyl-25,27-bis[2-(diethylamino)ethoxy]-26,28-dihydroxycalix[4]arene (BDAC), was designed and synthesized, which was first directly used as the absorbent in the platinum adsorption process. BDAC demonstrated outstanding platinum adsorption capability, achieving a maximum adsorption capacity of 232.02 mg·g^-1. BDAC also exhibited remarkable selectivity for platinum, capturing over 97 % of platinum in complex systems, while the adsorption of competing ions remained below 5 %. Furthermore, BDAC maintained high platinum adsorption efficiency after multiple adsorption-desorption cycles. The adsorption mechanism was elucidated through SEM-EDS, FT-IR, Raman spectroscopy, XPS, and DFT calculations. This work not only proposes an efficient method for platinum recovery but also lays the groundwork for the development of novel technologies based on supramolecular chemistry.