Fabrication of PDVB-VI@ZIF-8 core-shell microspheres as an effective and recyclable adsorbent for phenol

Abstract

In this study, a novel method was developed for the preparation of PDVB-VI@ZIF-8 composites with core-shell structures. The challenge of achieving spontaneous nucleation of ZIF-8 has been successfully overcome, allowing for ZIF-8 to self-assemble on the surfaces of polymeric nanoparticle microspheres. In the initial step, imidazole-modified polydivinylbenzene (PDVB-VI) microspheres were prepared through the surface modification of PDVB with 1-vinyl imidazole (VI). Subsequently, PDVB-VI@ZIF-8 microspheres, characterized by a core-shell structure were successfully synthesized using a solution-based method, with PDVB-VI microspheres serving as the core material. Remarkably, this method can be conducted at room temperature and boasts environmental friendliness, safety, and simplicity as key attributes. The resulting composite materials demonstrated excellent phenol adsorption capabilities in water. When compared to ZIF-8 in isolation, PDVB-VI@ZIF-8 exhibited significantly enhanced phenol adsorption and recovery rates. This improvement can be primarily attributed to the incorporation of the PDVB-VI core, which effectively increased particle size and decreased surface energy, thus preventing agglomeration and ultimately enhancing the mass-transfer and utilization efficiency of active sites. The adsorption kinetics, isotherms, and thermodynamics of PDVB-VI@ZIF-8 and ZIF-8 on phenol were explored using kinetic and adsorption isotherm models. The results of the Langmuir model showed that the maximal adsorption capacities (qm) of ZIF-8 and PDVB-VI@ZIF-8 were 2.40 mmol g-1 (225.86 mg g-1) and 3.79 mmol g-1 (356.68 mg g-1), respectively. This method provides a new approach for the preparation of core–shell advanced functional materials with mismatched topologies. It overcomes the limitations of metal-organic frameworks, which are prone to agglomeration and difficult to recover. Moreover, this method can be adapted for a wide range of applications.