Development of an azo-functionalized ion-imprinted polymer for selective recognition of palladium ions

Abstract

The current work reports the development of a new azo-functionalized ion-imprinted material for specific recognition of palladium ions (Pd2+). The ion-imprinted material was synthesized via a free radical polymerization approach, enabling convenient access to Pd2+. First, a maleimide-phenolic azo-functionalized ligand (MIZOH) was synthesized and combined with Pd2+ to form the corresponding [Pd(MIZO)2] complex. The copolymerization was then proceeded with utilizing 2,2-azobisisobutyronitrile (AIBN) as an initiator with styrene and divinylbenzene crosslinkers in the presence of the [Pd(MIZO)2] monomer complex. A solution mixture of thiourea/HNO3 was used to extract the Pd2+ ions. Various methodologies were employed to investigate the synthesized ligands, complexes, and polymers. Batches were conducted to evaluate the adsorption characteristics, including pH, capacity, contact time, selectivity, and recyclability. The results suggest that at a temperature of 30 °C and a solution pH of 6, the adsorption capacity was around 155 mg/g. The kinetic analyses exhibited a high degree of conformity with the pseudo-second-order kinetics. The Langmuir and Freundlich isothermal equations were constructed using equilibrium data, which exhibited a favorable level of conformity with the Langmuir isothermal model. Interference experiments show that the Pd2+ ion-imprinted polymer has a stronger attraction to Pd2+ than it does to the other ions that could be in the solutions. Additionally, there has been no appreciable decline in the affinity of the wasted polymer after at least five regeneration cycles.