Influence of 1:4;3:6-dianhydro-D-mannitol-based polyamide as an additive on morphology, permeability and antifouling performance of PES ultrafiltration membrane

A novel hydrophilic polyamide, PA-OH containing 1:4;3:6-dianhydro-d-mannitol (isomannide) fragment was synthesized and used as an additive to prepare a series of polyethersulfone (PES)/PA-OH hybrid membranes with different content of PA-OH by phase separation method. And the addition of PA-OH was expected to improve the hydrophilicity, permeability, and antifouling performance of the PES ultrafiltration (UF) membrane. The scanning electron microscopic and atomic force microscopic images showed that the addition of PA-OH greatly changed the morphology of membranes by increasing the porosity, pore size and pore density, and the hydrophilicity was also improved with the increased PA-OH content. Based on the UF experiment, when the PA-OH content was 3%, the fluxes of pure water and bovine serum albumin solution reached 213.1 and 92.6 L m(-2) h(-1), which were close to 1.5 times and 2 times those of the bare PES membrane, respectively. When the PA-OH content was 5%, the FRR1st reached 85.2%, which was distinctly higher than that of the compared PES/polyethylene glycol5% hybrid membrane of 74.3%. And the FRR2st of the PES/PA-OH5% hybrid membrane was still over 80%, which indicated its long-term antifouling performance. Thus, the PA-OH can be a candidate for the hydrophilic additives.