Functional upcycling of waste PET plastic to the hybrid magnetic microparticles adsorbent for cesium removal

Accumulation of mismanaged plastic in the environment and the appearance of emerging plastic-derived pollutants such as microplastics strongly demand technologies for waste plastic utilization. In this study, polyethylene terephthalate (PET) from waste plastic bottles was directly utilized to prepare a matrix of an adsorbent for cesium (Cs⁺) removal. The organic matrix of PET-derived oligomers obtained by aminolysis depolymerization was impregnated with bentonite clay and magnetite nanoparticles (Fe₃O₄ NPs), playing the roles as a major adsorptive medium for Cs⁺ removal and as a functional component to primarily provide efficient separation of the hybrid adsorbent from aqueous system, respectively. The obtained hybrid composite microparticles were next tested as an adsorbent for the removal of Cs⁺ cation from aqueous solutions. The adsorption process was characterized by fast kinetics reaching ca. 60% of the equilibrium adsorption capacity within 5 min and the maximum adsorption capacity toward Cs⁺ was found to be 26.8 mg/g. The adsorption process was primarily dominated by the cationic exchange in bentonite, which was not significantly affected by the admixture of the competing mono- and divalent cations (Na⁺, K⁺, and Mg²⁺). The proposed approach here exploits the sustainable utilization scenario of plastic waste-derived material to template complex multifunctional nanocomposites that can find applications for pollution cleaning and environmental remediation.