Fabrication of Bi-layer Polyethersulfone-based Nanofiltration Membrane Using Chitosan/Zeolite Nanocomposite Layer

Abstract

Hypothesis: This study constituted the effect of chitosan-zeolite active nanocomposite layer formation on the morphological, physico-chemical and separation properties, as well as the anti-fouling performance of the polyethersulfone-based nanofiltration membrane.Methods: The nanofiltration-based membrane was prepared by phase inversion method and its surface was modified through the dip-coating technique in the polymeric solution. The properties of the prepared membranes were investigated by Fourier transform infrared (FTIR) analysis, scanning electron microscopy (SEM), 3D surface images, contact angle, water content, pure water flux, salt and heavy metal rejection and anti-fouling performance techniques. Findings: The FTIR analysis results confirmed the formation of the chitosan/zeolite nanocomposite layer on the polyether sulfone-based membrane. Moreover, the scanning electron microscopy images of the surface and cross-section of the prepared membranes showed the formation of an active layer on the membrane surface. The results of surface analysis showed that the surface modification reduced the surface roughness of the membrane. In addition, the use of zeolite nanoparticles on the surface layer caused to an increase in the membrane water content. The pure water flux of bi-layer modified membrane showed an increase in water content of > 54% compared to the virgin membrane. The sodium sulfate salt rejection was measured > 70% for the bi-layer modified membrane. The chromium rejection increased from 69% for the virgin membrane to > 95% for the modified bi-layer membrane. The water contact angle results exhibited that the surface hydrophilicity of the membrane increased with the surface modification. The modified membranes showed superior antifouling ability as the flux recovery ratio increased from 85% to 93.6% and the irreversible resistance decreased considerably to 6.4%.

Keywords

• nanofiltration
• bi-layer membrane
• nanocomposite
• chitosan/zeolite
• heavy metals removal