Novel ultrafiltration membranes prepared from a multi-walled carbon nanotubes/polymer composite

Novel ultrafiltration membranes were prepared by incorporating multi-walled carbon nanotubes (MWNTs) into a matrix of brominated polyphenylene oxide (BPPO) and using triethanolamine (TEOA) as the crosslinking agent. The membranes exhibited not only high permeability and hydrophilicity but also excellent separation performance and chemical stability. Furthermore, the water permeability increased as the weight fraction of MWNTs increased, reaching a maximum of 487 L/m2 h at 5 wt% of MWNTs, while maintaining a 94% membrane rejection rate to egg albumin. The addition of TEOA into the BPPO/MWNTs casting solution might result in an increase in water permeation rate of membrane if the amount of TEOA exceeded a threshold value; however, the membrane rejection rate was essentially constant despite increasing the molar fraction of TEOA in the casting solution. Using an adequate amount of MWNTs and a proper TEOA/BPPO ratio, it is feasible to make MWNTs/polymer ultrafiltration membranes with both high permeation flux and excellent selectivity.