Hybridly charged NF membranes with MOF incorporated for removing low-concentration surfactants

Abstract

Water pollution is a growing issue that requires remediation. Surfactants, used in many domestic and industrial applications, are one of the emerging contaminants that require immediate concern. Removing low-concentration surfactants using nanofiltration (NF) membrane is a study that deserves attention. In this case, a mixed polyamide-based NF membrane was fabricated via interfacial polymerization (IP) using polyethylenimine (PEI) and piperazine (PIP) as monomers in aqueous solution. UiO66-NH2 and UiO66 were synthesized and incorporated into the polyamide layer to enhance the permeability of the prepared NF membranes. The pure water flux of the NF membranes reached 16.6 L m−2 h−1 bar−1 when UiO66-NH2 concentration in aqueous solution is 0.005 wt%, and the membrane showed decent rejection to divalent salts, 96.5% to MgCl2 and 85.6% to Na2SO4. The prepared membranes were utilized to remove surfactants with the concentration (100 mg L−1) below the critical micelle concentration (CMC) from water, and they showed good removal to both anionic and cationic surfactants. In addition, the durability of the fabricated NF membranes is acceptable. This work provides a feasible strategy for the fabrication of highly permeable NF membranes and demonstrates the capability of NF membrane for surfactants removal.