Using Design-Expert to Optimize the Properties of a Polyethersulfone Ultrafiltration Membrane Through the Incorporation of NH2-MIL-53(Fe) and PVP for Maximum Cr(VI) Removal and Flux

Abstract

In this study, an NH₂-MIL-53(Fe) functionalized membrane was fabricated for Cr(VI) removal from contaminated groundwater. Design-Expert was employed to determine the optimum membrane structure in order to enhance selective adsorption rate and flux by investigating two factors of metal–organic framework (MOF: 0–5 wt%) and polyvinylpyrrolidone (PVP: 0.1–1 wt%). NH₂-MIL-53(Fe) successfully synthesized was proved using FESEM, FTIR, EDS, and XRD analyses. NH₂-MIL-53(Fe) functionalized membrane was prepared, and the properties were recognized using FESEM, EDS, EDX-mapping, and CA. According to these analyses, the synthesized MOF improved membrane properties such as hydrophilicity and porosity. Moreover, the MOF crystals were well immobilized in the polymer solution and uniformly distributed in the composite membrane. On the basis of the statistical results, PVP had a much more significant effect on adsorption percentage than MOF. In accordance with the Design-Expert result, the optimum structure of the MOF functionalized membrane containing 3.6 wt% of NH₂-MIL-53(Fe) and 0.4 wt% of PVP exhibited a removal percentage of 87% and flux of 101 L m⁻² h⁻¹. Investigation of the effect of TDS did not indicate any interference with Cr(VI) adsorption by the adsorbent. Additionally, membrane repeatability and regeneration tests, used in five cycles, confirmed the membrane's long-term durability and performance.