A novel nanofibrous PAN ultrafiltration membrane embedded with ZIF-8 nanoparticles for effective removal of Congo red, Pb(II), and Cu(II) in industrial wastewater treatment

A novel Polyacrylonitrile (PAN) composite membrane involving ZIF-8 nanoparticles, named as ZIF-8/PAN membrane, was obtained via electrospinning to remove the Congo red (CR), Pb(II) and Cu(II) ions in industrial wastewaters, during which the adsorption mechanisms were examined in this study. The adsorption efficiency of the electrospun ZIF-8/PAN membrane was as high as 89%, 92% and 76% for CR, Pb(II) and Cu(II), respectively. Comparative analysis showed that ZIF-8 nanoparticles embedded in the ZIF-8/PAN membrane accounted for these enhanced adsorption capabilities. The adsorption behaviors of the ZIF-8 nanoparticles were investigated through experiments and theoretical analysis, and the results unraveled that the adsorption for CR by the ZIF-8 was mainly including electrostatic interaction, hydrogen bonding and π−π interaction, while those for Pb(II) and Cu(II) were mainly caused by ion-exchange and chemical adsorption. Parametric studies were conducted to optimize the conditions for removing CR, Pb(II), and Cu(II) by ZIF-8 nanoparticles, during which all of pollutants showed different reactions to the solution pH. This work not only develops a novel ZIF-8/PAN composite membrane for effective removals of pollutants, but also reveals the underlying mechanisms of pollutants adsorption in terms of molecular interactions, providing important understandings on fibrous materials design for efficient heavy metals and dyes removals in industrial wastewater treatment.