Carbon nanotubes-blended poly(phenylene sulfone) membranes for ultrafiltration applications

Abstract

Multi-walled carbon nanotubes (MWCNT) were carboxylated by a chemical method. Poly(phenylene sulfone) (PPSU), MWCNT and functionalized (carboxylated) MWCNT/poly(phenylene sulfone) (PPSU) blend membranes were synthesized via the phase-inversion method. The resultant membranes were then characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle. The FMWCNT blend membranes appeared to be more hydrophilic, with higher pure water flux than did the pure PPSU and MWCNT/PPSU blend membranes. It was also found that the presence of multi-walled carbon nanotubes (MWCNTs) in the blend membranes was an important factor affecting the morphology and permeation properties of the membranes. The model proteins such as trypsin (20 kDa), pepsin (35 kDa), egg albumin (45 kDa) and bovine serum albumin (69 kDa) rejection experiments were carried out under identical operational conditions employing both PPSU and blend membranes. The membranes were also subjected to the determination of molecular weight cut-off (MWCO) using different molecular weights of proteins. During trypsin ultrafiltration, PPSU/MWCNT and PPSU/FMWCNT membranes showed a slower flux decline rate than did the PPSU membrane.