PES mixed-matrix membranes incorporating ZIF-8@MXene nanocomposite for the efficient dye/salt separation

Abstract

To improve the flux, anti-fouling and dye separation performance of PES-based membranes, PES mixed-matrix membranes (MMMs) blended with ZIF-8@Ti3C2Tx composites were fabricated via a facile one-pot microemulsion strategy. The introduction of hydrophilic components in the microemulsion into the PES matrix enhanced the pore structures and surface polarity of the resulting MMMs, causing them to exhibit high permeation and anti-fouling performance compared to both neat PES and MMMs with ZIF-8. The optimal membrane flux and anti-fouling performance were found to be 280 L·m−2·h−1 and 91 % (bovine serum albumin rejection), respectively, at 3 % microemulsion content. The well-distributed ZIF-8@Ti3C2Tx composites in the MMMs interact with dye molecules, which strengthens the dye retention from high-salinity wastewater. Further, the pore size of the MMMs was positively correlated with the flux but negatively correlated with dye retention. In particular, the M-3 membrane exhibited high flux (140 L·m−2·h−1) and up to 98 % dye rejection in high-salinity wastewater, but its rejection of salt ions was <5 %. In addition, the dye rejection recovery rate of M-3 after each washing exceeded 93 % over 5 fouling/backwashing cycles. These results strongly suggest that MMMs incorporated with ZIF-8@Ti3C2Tx composites have promising application prospects for removing trace dye pollutants from high-salinity wastewater.