Diels-Alder-imprinted furan-thiosemicarbazide sorbents for selective removal of cadmium (II) ions

The exploration of removing heavy metals from water solutions with specific sorbents is a compelling research area. However, the selectivity of these sorbents towards particular metals is limited. To address this, an innovative furan-thiosemicarbazide-based chelating polymer within a poly(acrylonitrile-co-divinylbenzene) framework (FTCP), has been synthesized. This new polymer demonstrates a high selectivity for capturing Cd²⁺ ions. To further enhance its performance, the polymer was cross-linked with a bis(maleimido)ethane (BME) through a Diels-Alder reaction, effectively embedding the Cd²⁺ ions within its structure, resulting in a ion-imprinted material (Cd-II-P) after elution with EDTA and nitric acid. The development and modification of this polymer were meticulously verified using FTIR and NMR spectroscopy, while the chelation efficiency for Cd²⁺ was evaluated through XPS and FTIR analysis. Additionally, the sorbent's surface characteristics were examined via SEM, revealing the polymer's morphology. Notably, the Cd-II-P variant exhibited superior specificity for Cd²⁺ ions compared to other metals, with the most effective adsorption occurring at a pH of 5. This sorbent reached an adsorption capacity of 341 mg/g, aligning with the Langmuir adsorption isotherm model and adhering to a pseudo-second-order kinetics model in its adsorption process.