Synthesis of novel microporous nanocomposites of ZIF-8 on multiwalled carbon nanotubes for adsorptive removing benzoic acid from water

- A controlled route was to synthesize novel nanocomposites of ZIF-8 growing on MWNTs.
- The effective micropores for selective BA adsorption were formed in ZIF-8/MWNTs (B).
- ZIF-8/MWNTs-25 (B) showed high and stable adsorption performance for BA removal.

This study reports a controlled route for straightforward synthesizing novel microporous nanocomposites of ZIF-8 type metal-organic frameworks material incorporated with multiwalled carbon nanotubes (MWNTs). The prepared ZIF-8/MWNTs samples were characterized by XPS, XRD, SEM, TEM, N2 adsorption and TGA experiments to investigate the effects of synthesis methods on the formation of the hybrid composite structure of ZIF-8 nanocystals growing on MWNTs. The ZIF-8/MWNTs nanocomposites were successfully synthesized by the method of adding MWNTs into a zinc nitrate solution prior to react with a 2-methylimidazole solution and the microporous structures of the ZIF-8/MWNTs nanocomposites were controlled by the MWNTs content. As an adsorbent for adsorptive removing benzoic acid (BA) from water, the prepared ZIF-8/MWNTs-25 (B) nanocomposite exhibits the best adsorption capacity of 303 mg/g, about 65 mg/g higher than the ZIF-8. The improvement in the BA adsorption is due to the pore/size-selective BA adsorption of the effective micropores yielded by the ZIF-8/MWNTs hybrid composite structure, in addition to the basic-acid, coordination, and π-π stacking interactions between ZIF-8 and BA. The high adsorption capacity and good reusability of the ZIF-8/MWNTs-25 (B) nanocomposite suggests that it can be applied as novel adsorbents showing attractive potential.

The ZIF-8/MWNTs nanocomposites with novel microporous structures of ZIF-8 growing on MWNTs exhibit improved adsorption performance for removing benzoic acid from water.87