Construction of Ag@ZIF-8/PVDF mixed-matrix ultrafiltration membranes with high separation performance for dye from high-salinity wastewater by microemulsion coupling with blending

Abstract

In order to improve the separation performance and anti-fouling property of polyvinylidene fluoride (PVDF) ultrafiltration membranes, PVDF mixed matrix membranes (MMMs) were obtained by mixing PVDF with Ag@ZIF-8 using a simple one-pot microemulsion strategy. First, both Ag and ZIF-8 were generated in one micelle of the microemulsion during the formation of composites. After in-situ polymerization of microemulsion， the latex containing Ag@ZIF-8 was blended with PVDF by phase-inversion method to construct the MMMs. The small-sized Ag particles were closely distributed on the surface of ZIF-8 after the formation of ZIF-8 in micelles. The subtle interaction forces between the two facilitated the distribution of the composite in the PVDF matrix. In addition, the hydrophilic component in the latex improves the pore structure, the permeation and anti-fouling performance of the PVDF matrix compared to neat PVDF and the MMM with ZIF-8 added. Mixed-matrix ultrafiltration membranes with 0.3 wt% of microemulsion containing Ag@ZIF-8 exhibited good permeation (Jw = 222 L m−2 h−1) and flux recovery rate (FRR = 82%). The well-distributed Ag@ZIF-8 in PVDF polymeric matrix strengthened the dye retention of MMMs from high-salinity wastewater, due to the interaction between Ag@ZIF-8 and dye molecules. This mixed-matrix ultrafiltration membrane also showed optimum dye rejection (97.3%) and low salt rejection (0.2%). The MMMs combined with Ag@ZIF-8 in this work are promising for the removal of dye contaminants for high-salinity wastewater, so as to achieve the goal of advanced treatment for high-salinity wastewater.