Desalination Pervaporation Using Modified Zwitterionic Poly(arylene ether sulfone) Membranes

Freshwater is becoming more and more scarce, and the need to make use of other water resources is critical. Although processes such as Sea Water Reverse Osmosis (SWRO) exist, these processes are not without drawbacks, such as a brine with a high salt concentration being a byproduct of SWRO. Pervaporation is a potential solution to this problem, however the membranes used in these processes are prone to fouling and the high salt conditions are difficult to work around. Incorporating zwitterions into the polymeric backbone of these membranes has proven to be an effective way to increase fouling resistance. In this work, sulfobetaine – based zwitterions were incorporated into the backbone of poly(arylene ether sulfone) to synthesize sulfobetaine – modified poly(arylene ether sulfone) (SB-PAES) membranes, which were then tested in a cross-flow pervaporation apparatus to analyze salt rejection. SB-PAES membranes were cast with two different methods to create a consistent casting protocol. It was determined that casting solutions with a lower weight percent in petri dishes was optimal, but still needs more exploration. The SB-PAES membranes were tested with feed solutions of pure water and salt solutions with concentrations of 1 g/L, 5 g/L, and 10 g/L. Both 50% and 25% charge SB-PAES membranes were tested. The 50% charge membranes showed good flux and salt rejection over 99.9% for a 10 g/L feed solution, while the 25% charge membranes showed less flux and salt rejection around 85% for a feed solution of 10 g/L.