Thin film nanocomposite membranes fabricated via 2D ZIF-67 nanosheets and 1D nanofibers with ultrahigh water flux for dye removal from wastewater

Abstract

Thin-film nanocomposite (TFN) membranes based on metal–organic frameworks (MOFs) have received increasing attention in the field of water treatment. However, TFN membranes with both high permeance and rejection rates are highly desired. In this study, ultra-thin ZIF-67 was synthesized and TFN membranes were fabricated by combining the obtained 2D ZIF-67 with cellulose nanofibers (CNF) and carbon nanotubes (CNTs). The nanofibers not only fill the gaps between the ZIF-67 nanosheets but also form an intercalation layer between the ZIF-67 nanosheets and function as a water transport pathway, leading to a significant enhancement of water permeance. By introducing CNF into the ZIF-67-embedded matrix, the dye rejection rates increase to 96.8 % and 93.3 %, respectively, with water permeance of about 90.0 L⋅m−2⋅h−1⋅bar−1. Further introducing CNT into the CNF/ZIF-67 membrane further improved the water permeance to 207.8 L⋅m−2⋅h−1⋅bar−1, while a dye rejection rate of 95.1 % was documented. The results indicate that the introduction of nanofibers into 2D MOF matrix to form TFN membranes has great potential for wastewater treatment.