Polydopamine assists the continuous growth of zeolitic imidazolate framework-8 on electrospun polyacrylonitrile fibers as efficient adsorbents for the improved removal of Cr(vi)

Abstract

The integrated combination of zeolitic imidazolate framework-8 (ZIF-8) into electrospun fibers and surface functioned polyacrylonitrile (PAN) fibers with polydopamine (PDA) both showed great potential in the removal of heavy metal ions (such as Cr(VI)) from aqueous solution in our previous works. Based on these results, here we report a more facile strategy to fabricate composite ZIF-8@PDA/PAN fibers as efficient adsorbents by PDA coating assisted ZIF-8 continuous growth on electrospun PAN fibers. Benefiting from the abundant functional groups (including amino and hydroxyl) of PDA, ZIF-8 particles effectively grew and were loaded on the surface of fibers with uniform distributions and thicker ZIF-8 layers were obtained easily by prolonging the reaction time. The obtained composite ZIF-8@PDA/PAN fibers retained higher surface areas (the maximum of 299.9 m² g⁻¹) and appropriate pore sizes, meanwhile they exhibited super hydrophilicity and good water stability, which are well known to be vital for the removal of Cr(VI). Thus, the composite fibers exhibited significant removal efficiency (especially more than 90% at a lower initial Cr(VI) concentration) and also higher adsorption capacity (with a maximum of 212.7 mg g⁻¹) and good recyclability.