Adsorption of heavy metals and antibacterial activity of silicon-doped chitosan composite microspheres loaded with ZIF-8

A bifunctional composite microsphere adsorbent with high adsorption and antimicrobial activity was synthesized by combining zeolite imidazolate framework (ZIF-8) chitosan microspheres doped with silica (CS/DS) prepared by electrospraying method for removing heavy metal ions Pb2+ and Cu2+. The samples were characterized by chemical, morphological, thermal behavior, specific surface area and pore size analysis. Compared with chitosan microspheres and CS/DS, CS/DS@ZIF-8 has good crystallinity, high specific surface area, multi-pore size distribution, better thermal stability and more active groups. The adsorption process of Pb2+ and Cu2+ on CS/DS@ZIF-8 conformed to the Langmuir model and Pseudo 2nd kinetics model, of which the maximum adsorption capacities were 340.94 mg/g and 308.27 mg/g, respectively, which were better than those of CS and CS/DS microsphere adsorbents. At the same time, the composite microspheres have excellent antibacterial properties and have application potential in solving practical wastewater treatment. It is worth mentioning that CS/DS@ZIF-8 maintains 81.3 % and 72.9 % adsorption rates for Pb2+ and Cu2+ after five cycles. This study aims to help design new bifunctional adsorbents with the ability to remove chemical and biological pollutants to promote practical application scenarios.