Polymeric ultrafiltration membranes modified with fly ash based carbon nanotubes for thermal stability and protein separation

Abstract

The fly ash based carbon nanotubes (CNTs) were used to modify polymeric ultrafiltration membranes for protein separation. The phase inversion method was used to synthesize asymmetric polysulfone (PSF) membranes using 1-methyl-2-pyrrolidone (NMP) as solvent. Polyethylene glycol (PEG) and synthesized fly ash CNTs with different proportions were used as pore former and additive, respectively. The membranes' functional, morphological, and permeation-based characterizations were conducted by using different characterization techniques, namely FTIR, AFM, FESEM, TGA, and water flux analysis. Liquid-liquid displacement porosimetry (LLDP) was used to demonstrate the membranes' pore size distribution. Separation efficiency, as well as the antifouling effect of the modified membranes, was perceived with the help of the model protein bovine serum albumin (BSA). The modified membranes showed improved hydrophilicity as the SWCA decreases from 73.4° to 46.2°. The AFM analysis shows that the surface roughness of the membranes decreases from 30.07 (CM0) to 12.05 (CM9) confirming positive antifouling nature. The maximum flux recovery ratio of 91.99% and BSA rejection of 84.11% were obtained with improved thermal stability as shown by the TGA analysis.

Keywords

• Ultrafiltration membranes
• Carbon nanotubes
• Fly ash
• Thermal stability
• Protein separation
• Antifouling