Controllable preparation of porous hollow carbon sphere@ZIF-8: Novel core-shell nanomaterial for Pb2+ adsorption

A novel core–shell nanophere based on porous hollow carbon spheres (PHCS) and ZIF-8 was successfully prepared by a simple hydrothermal method . The PHCS as a supporter could effectively inhibit the aggregation of ZIF-8 nanoparticles and increased its dispersibility. Results indicated that the obtained PHCS-15@ZIF-8 nanophere with porous structure, high specific surface area (1140 m 2  g −1 ) and numerous oxygen-containing functional groups exhibited an excellent sorption capability for Pb 2+ . The maximum adsorption capacity of PHCS-15@ZIF-8 for Pb 2+ reached up to 462.9 mg g −1 , higher than the pure ZIF-8 (310.5 mg g −1 ). The adsorption data better followed with Freundlich isotherm and pseudo-second-order model. The effects of PHCS content, initial concentration, solution pH and competing ions on the sorption performance were discussed in detail. The possible sorption mechanism was also systematically analyzed by zeta potential , FT-IR, AAS and XPS studies. In addition, desorption and regeneration studies showed that PHCS-15@ZIF-8 still remained over 90% removal efficiency after five cycles.