Ethaline deep eutectic solvent as a hydrophilic additive in modification of polyethersulfone membrane for antifouling and separation improvement

In this research, fabricating and modifying of polyethersulfone (PES) nanofiltration membrane were reported by using deep eutectic solvents (DESs) as a novel modifier for the membranes. The applied DES was produced by mixing ethylene glycol (EG) and choline chloride (ChCl). It is commonly known as ethaline. Ethaline was exploited as a hydrophilic additive into casting solution to formulate a novel PES/DES membrane by the non-solvent induced phase separation (NIPS) process. The PES/DES membranes were characterized by scanning electron microscope (SEM), contact angle measurement, atomic force microscope (AFM), attenuated total reflection-Fourier-transform infrared spectroscopy, mechanical strength and hydraulic testing of distilled water. Their performances were evaluated by bovine serum albumin (BSA) and dye solutions filtration and separation tests. The effects of different concentrations of DES loading were evaluated systemically on the membrane performance. The maximum pure water flux was 241.3 L/m²h for 2 wt% PES/polyvinyl pyrrolidone (PVP)/DES membrane, which it was 23 times of neat PES membrane (without PVP and DES) and 1.3 times of PES/PVP membrane. The pure water flux of PES/DES membrane (without PVP) was 17.6 L/m²h, presenting that the ethaline is not a good pore former. The dye and BSA rejections for all membranes were higher than 98% and 99%, respectively, showing suitable separation ability. Also, the influence of the DES on antifouling properties shows that the flux recover ratio of the DES blended membranes improved. The results showed that the ethaline DES is not a good pore former, but it is a good antifouling additive.