Halloysite nanotubes for regulating thermodynamics and kinetics of polysulfone/poly (ethylene-co-vinyl alcohol) membranes with enhanced permeability

Abstract

Controlling membrane morphology is crucial to improving the mechanical strength (MS) and hydrophilicity of porous membranes. Here we report on the fabrication of mixed matrix membranes (MMMs) free of macrovoids via non-solvent-induced phase separation (NIPS). Hydrophilic Halloysite nanotubes (HNTs) and poly (ethylene-co-vinyl alcohol) (EVOH) were mixed with Hydrophobic polysulfone (PSF) in the presence of polyethylene glycol (PEG) to fabricate MMMs. The results showed the formation of PSF/EVOH-MMMs with a spongy structure when the content of HNTs varied from 0.06- 0.12 wt.%, owing to the formation of strong hydrogen bonds between PSF, EVOH, PEG, and HNTs, confirmed by molecular dynamics (MD) simulations. The MS of MMMs with 0.12 wt.% HNTs was increased 2.2-fold (up to 6.22 MPa), while the contact angle (CA) was lowest at 47.42 ± 1.9°. In addition, the water permeability increased by a factor of 1.7 up to 419 L m−2 h−1 bar−1. The rejection rates of MMMs (M12) for oil and BSA were >90% and >95%, respectively. While the MMMs had > 90% flux recovery for both oil and BSA. We predict that this study will provide a method for controlling dope thermodynamics, formation dynamics, and morphology of MMMs while maintaining promising properties for improved separation performance.