Synthesis and characterization of ZIF-8-based PVDF mixed matrix membranes and application to treat pulp and paper industry wastewater using a membrane bioreactor

Abstract

The metal–organic framework (MOF) zinc imidazolate framework-8 (ZIF-8) is synthesized by a solvothermal method and added into a polyvinylidene fluoride (PVDF) membrane to study its pollutant removal performance using pulp and paper industry wastewater. A membrane bioreactor (MBR) lab-scale experimental setup is used to study the pollutant removal performance. The synthesized ZIF-8 nanoparticles are embedded into the PVDF membrane at different weight percentages, viz., 0.25, 0.50, 0.75, 1.00, and 1.20 wt%. The characterization of the pure PVDF membrane and ZIF-8 based mixed matrix membranes (MMMs) is carried out using different characterization techniques, such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to investigate the chemical composition of the membranes. The morphology and uniform dispersion of ZIF-8 in the MMMs are studied using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and atomic force microscopy (AFM). The water contact angle shows that the MMMs are more hydrophilic than the pure PVDF membrane. The tensile strength and elongation at break are used to investigate the mechanical properties of the membranes. The effect of addition of ZIF-8 nanoparticles on the PVDF mixed matrix membrane performance is studied using the pure water flux, pulp and paper water flux, flux recovery ratio and antifouling characteristics. The MBR experiments with the ZIF-8 based PVDF MMMs show 93.93% chemical oxygen demand (COD), 93.57% biochemical oxygen demand (BOD₅), and 99.3% total suspended solids (TSS) removal in permeate water. The different characteristics of the MMMs are enhanced after the addition of ZIF-8 crystals. The prepared ZIF-8 based PVDF MMMs show better pollutant removal performance and has great development potential for pollutant removal from pulp and paper industry wastewater.