Polypiperazine-amide nanofiltration membrane incorporated with poly(ethylene glycol) derivative for electrodialysis concentrate treatment

We report a facile approach to prepare antifouling nanofiltration (NF) membrane to treat electrodialysis (ED) concentrate which contained anionic polyacrylamide (APAM). The NF membrane was fabricated through trimesoyl chloride (TMC) reacting with the hydrophilic poly(ethylene glycol) (PEG) derivative (i.e. Jeffamine) in piperazine (PIP) aqueous solution by means of interfacial polymerization (IP). The membrane surface characterization, performance of permeation flux and antifouling property were throughly investigated in this paper. The presence of Jeffamine in the polyamide matrix was verified by the Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The salts and APAM rejection was raised up and the permeation flux decline was slowed down for the ED concentrate treatment, which indicated that the antifouling performance was improved through adding Jeffamine. The optimized Jeffamine addition amount was 15   wt% (in the piperazine solution) at which the largest pure water flux enhancement and the best antifouling performance were achieved. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the polypiperazine-amide NF membrane exhibited that the surface smoothness was improved. Accordingly, it could be concluded that the addition of Jeffamine improved the NF membrane hydrophilicity and surface smoothness which could lead to the permeation flux enhancement and the antifouling property improvement.