ZIF-67/SA@PVDF Ultrafiltration Membrane with Simultaneous Adsorption and Catalytic Oxidation for Dyes

Abstract

Due to their stable chemical properties and complex structures, dyes are difficult to be removed from water. Herein, a ZIF-67/SA@PVDF (ZSA3@PVDF) mixed matrix membrane has been fabricated by incorporating silicon aerogel (SA) and zeolitic imidazolate framework material 67 (ZIF-67) nanoparticles in a polyvinylidene fluoride (PVDF) membrane for the removal and degradation of dyes from water. The influence of SA and ZIF-67 on the morphology and structure of the membrane was confirmed using scanning electron microscope (SEM) and atomic force microscope (AFM). In ZSA3@PVDF membrane, both SA and ZIF-67 are highly porous nanomaterials that possess good adsorption capacity, as confirmed by the Brunauer–Emmett–Teller (BET) result. In addition, the cobalt (Co) element of ZIF-67 can catalyze peroxymonosulfate (PMS) to generate strong oxidizing sulfate radicals (SO42−), contributing to improving regeneration capacity of the ZIF-67/SA@PVDF membrane. The water flux of ZSA3@PVDF membrane is 427.6 L m−2 h−1 bar−1, and the Methylene blue (MB) removal rate is higher than 99% when filtrating 100 mL MB solution (5 mg/L). The regeneration test result shows that the removal rate of the ZSA3@PVDF membrane is still above 98% after five cycles of adsorption of MB. The self-cleaning experiment shows that the adsorption of SA in the ZSA3@PVDF membrane promotes the catalytic performance of the membrane, showing a better self-cleaning ability. The ZSA3@PVDF membrane provides a new strategy for the removal of dyes in the advanced purification of dye wastewater.