Fe-HNT@PVP/PEI membranes for enhanced dye removal and water purification

Abstract

This study envisages the improvement in adsorption efficiency of polyetherimide (PEI) membranes by integrating Fe-doped halloysite nanotubes (Fe-HNTs) into polyvinylpyrrolidone (PVP)-modified PEI matrices for reducing water contamination caused by dyes, which are known for their harmful impact on aquatic life. Fe-HNTs were synthesized via the Co-precipitation method and incorporated into PEI/PVP membranes at 1 % and 2 % concentrations by utilizing a simple, non-destructive phase inversion technique. The modification of the PEI matrix by PVP/Fe-HNTs brought significant structural alterations, improved hydrophilicity, and morphological changes in the membranes. These changes were witnessed through techniques including Fourier Transform Infra-Red (FTIR), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The 2 %-Fe-HNTs@PVP/PEI membrane demonstrated superior adsorption capacity for methylene blue (MB) dye, with significantly enhanced removal efficiency compared to the unmodified PVP/PEI membrane. Kinetic studies revealed a fast adsorption rate, fitting with pseudo-first-order and Langmuir isotherm models. The membrane also exhibited excellent reusability, maintaining its efficacy over multiple cycles. In textile effluent treatment trials, the modified membrane achieved an impressive 85 % removal of dye pollutants within 300 min, underscoring its appropriateness for environmental remediation and purification of water.