Preparation of Thermoresponsive Imprinted Polymers of Pd( II )‐ EDTA Complexes and Their Temperature‐Controlled Selective Adsorption–Desorption Properties

ABSTRACT Palladium is an important metal element in many fields, and the contradiction between supply and demand is very serious, so designing and developing a novel material with a precise separation effect is very important for its facilitation of recovery. In this work, the thermos‐responsive technology was combined with the imprinting technology to design and prepare a thermos‐responsive polymer‐regulated smart ion‐imprinted polymer (Pd(II)‐EDTA‐TIIP), which can adjust its structure by controlling the external temperature to achieve good selective adsorption and separation performance. Firstly, the microstructure, surface morphology, pore size distribution, and size were characterized, and then its separation and purification performance, reusability, and adsorption mechanism for palladium enrichment from complex environments were studied. The results showed that Pd(II)‐EDTA‐TIIP had specific adsorption for Pd(II), and the saturated adsorption amount was 0.085 mmol/g; the desorption rate was 78.9% in the binary mixed solution. After seven adsorption/desorption cycles, the change in adsorption and desorption amount was small, indicating that the prepared Pd(II)‐EDTA‐TIIP possessed excellent reusability. The study of its adsorption behavior showed that compared with the pseudo–second‐order kinetic model, the pseudo–first‐order model was more suitable for describing the adsorption kinetic process. Compared with the Freundlich model, the fitted values obtained by Langmuir model fitting were larger and more suitable for describing adsorption behavior, which belonged to the monomolecular layer adsorption. The prepared Pd(II)‐EDTA‐TIIP was used to separate the platinum group metals from the wasted catalytic leaching solution that contained the platinum group metals; the content of the platinum group metals was increased from 41.14% to 69.78% after one cycle of adsorption and desorption operation.