High performance nanofiltration in BUT-8(A)/PDDA mixed matrix membrane fabricated by spin-assisted layer-by-layer assembly

Abstract

The membrane fouling is a notorious problem in the practical application of separation membranes. In this study, a mixed matrix membrane based on the MOF BUT-8(A) and the polymer polydiallyldimethylammonium chloride (PDDA) has been prepared on a hydrolyzed polyacrylonitrile (HPAN) substrate by the spin-assisted layer-by-layer assembly (spin-LbL) method. Thanks to the high porosity, high stability, moderate hydrophilicity, and electronegative nature of BUT-8(A), and the good compatibility between BUT-8(A) particles and PDDA polyelectrolytes, the prepared (BUT-8(A)/PDDA)3-HPAN membrane showed high water permeances (over 164 L m−2 h−1 MPa−1) and high rejection rates (over 91.4%) for many dyes in water. Furthermore, the membrane exhibited superior antifouling performance in nanofiltration (NF) with a high flux recovery rate (95.5%) when humic acid (HA) was used as foulant. The high antifouling performance is resulted from tuning hydrophilicity and electronegativity of the membrane surface. These results suggest that the nanofiltration performance of a MOF-based membrane can be well adjusted by a judicious choice of the membrane components and fabrication methods.