Highly effective adsorption, porous and charged CAP@Ui0-66-NH2@PPy hybrid fibrous membrane based on MOFs for Cr (VI) removal from wastewater

Heavy metal wastewater pollution has been a globally important and serious issue for the industrial manufacturing center. Herein, we developed a novel CAP@Ui0-66-NH 2 @PPy nanocomposite fibrous membrane, by combining the in-situ growth and oxidative polymerization technical routes, which possessed a high specific surface area and abundant amino-active sites to remove Cr (Ⅵ). Systematic characterization showed that the porous structure and in situ growth of MOF provided sites for polymerization of charged polypyrrole (PPy), resulting in the large specific surface area (78.837 m 2 /g) of CAP2@Ui0-66-NH 2 @10 %PPy. The maximum adsorption capacity was as high as 312.70 mg/g at 298 K, which was significantly better than that of CAP (CA and PVP electrostatic spinning and then washing off the PVP) nanomembranes. The adsorption process was consistent with the proposed secondary kinetic and Langmuir model, and the high adsorption capacity was maintained after five rounds of cyclic adsorptions. Through XPS analysis, the abundant amino groups on the surface of the adsorbent material were protonated, caused the electrostatic attraction and ion-exchange interaction with the anion Cr(Ⅵ). These protonated amino groups were able to reduce the toxic Cr (Ⅵ) to non-toxic Cr (Ⅲ), which was immobilized on the surface of the material through chelation. The MOF lattice achieved in-situ growth on porous CA nanofibrous membranes, which significantly enhances the mass-transfer dynamics and the membrane cycling stability, the amine-based functionalization of the UI0-66-NH 2 improved the coordination activity and increased the adsorption efficiency, and polypyrrole (PPy) conductive layer promoted the directional migration of Cr (VI) and effectively suppressed the interference of competing ions. In sum, the prepared CAP@Ui0-66-NH 2 @PPy hybrid fibrous membranes showing great potentially applicable for heavy-metal wastewater treatment.