Nanoporous Zeolitic Imidazolate Framework-8 Nanoparticles for Arsenic Removal

Herein, we report a solvent-free self-templating strategy for rapid synthesis of nanoscale hierarchically porous zeolitic imidazolate framework-8 (HP-ZIF-8) with micro-, meso-, and macropores. ZIF-8 crystals were produced in situ on ZnO nanoparticles via vapor deposition of 2-methylimidazole, and hierarchical nanopores were obtained after selectively etching ZnO. ZnO nanoparticles acted as both a Zn source and a meso-/macropore template for HP-ZIF-8. Systematic arsenic adsorption experiments showed that the presence of meso-/macropores can effectively enhance and accelerate arsenic removal via chemisorption. As a result, HP-ZIF-8 exhibited an As(III) adsorption capacity of 104.9 mg/g, nearly double that of traditional ZIF-8 nanoparticles, despite having remarkably more micropores. This study provides a highly adsorbable strategy to fabricate hierarchical porous metal–organic frameworks for pollutant removal.