Fast and highly selective anionic azo dye removal over unique PVDF/MIL-100(Cr) mixed matrix membranes

Abstract

Water pollution is a major challenge in the industrial era that gained the attention of researchers, especially for dye wastewater. Membrane technology is applied to address this issue due to its efficient and effective process. MIL-100(Cr) is a metal-organic framework that becomes an interesting material in membrane technology due to its highly porous characteristics (pore sizes of 24 Å and 29 Å), large surface area, and decent stability. In this study, polyvinylidene fluoride (PVDF) was modified with MIL-100(Cr) to fabricate PVDF/MIL-100(Cr) mixed matrix membranes (MMMs) for congo red (CR) dye removal. Furthermore, the membrane performances were determined by its permeability, selectivity, and antifouling properties. The results show that adding MIL-100(Cr) could enhance the membrane’s porosity and average pore size, which led to a boost in membrane permeability. Interestingly, the rejection of the membrane is maintained at a remarkably high level, above 95%, because of the electrostatic repulsion between the membrane surface with anionic congo red. The optimum concentration of MIL-100(Cr) is 1% (w/w), with a permeability of 50.90 L m⁻² h⁻¹ and rejection of 99.9%. Moreover, the flux recovery ratio (FRR) is around 90%, showing notable resistance to the fouling phenomena.