High performance membrane distillation membranes with thermo-responsive self-cleaning capacities

A thermo-responsive composite membrane was fabricated by electrospinning a temperature-sensitive skin layer composed of poly (N-isopropylacrylamide)/polystyrene (PNIPAM/PS) on a superhydrophobic polytetrafluoroethylene (PTFE) fabric substrate. During the membrane distillation (MD) process with a 35 g/L NaCl feed solution, the PNIPAM/PS-PTFE membrane showed a high average permeate flux of 35.78 L/(m2·h) (LMH), which is 1.6-fold higher than that of commercial PTFE membrane (22.06 LMH). Meanwhile, the PNIPAM/PS-PTFE membrane maintained a salt rejection of 99.99 %. Noteworthily, the prepared membrane possessed excellent durability for long-term MD operation and an improved fouling resistance. Even if organic foulants deposited on the membrane surface, the permeate flux could be recovered up to ∼100 % with thermal actuation cleaning. The recovery rate was much higher than that of the commercial PTFE MD membrane. More significantly, after 90 h of MD operation with real landfill leachate, the permeate flux remained 85 % with the assistance of thermal actuation cleaning. This work exemplified an effective strategy for thermo-responsive membrane preparation, which can achieve both high permeate flux and fouling reversibility. The novel thermo-responsive MD membrane is worthy of being introduced into treating wastewater containing organic foulants.