Photocatalytic degradation of malachite green using PVDF membranes doped with Fe₃O₄ nanoparticles: role of porosity and surface roughness

Abstract

We report on a cost-effective and time-efficient approach to synthesize flexible membranes of polyvinylidene fluoride (PVDF) doped with varying concentrations of Fe3O4 nanoparticles (FNP). The membranes exhibit a uniform dispersion of FNPs, a β-phase structure, and porous morphology, as confirmed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements. Fourier Transform-Infra Red (FTIR) and x-ray Photon spectroscopy (XPS) analysis was also performed for the identification of structural and chemical parameters of PVDF:FNP membranes. Photocatalytic degradation of malachite green (MG) dye under ultraviolet (UV) irradiation was assessed using the PVDF:FNP membranes. The results demonstrate a significant enhancement in the degradation efficiency and rate constant of the photocatalytic process with the utilization of PVDF:FNP membranes compared to FNP alone. Among the various concentrations tested, the PVDF membrane with 7% FNP doping exhibited the highest degradation efficiency of 98.39% and a notable apparent rate constant of 0.07048 min−1 in 60 min. The improved photocatalytic performance can be attributed to the larger surface area and enhanced accessibility of active sites in PVDF:FNP membranes, facilitating better control of the reaction environment and reducing the recombination rate of electron–hole pairs. This study suggests that PVDF:FNP membranes hold great promise for water purification applications, offering flexible membranes with superior degradation efficiency and enhanced reusability.