Controllable modification of polymer membranes by LDDLT plasma flow: Membrane module scale-up and hydrophilic stability

The modification of PE hollow fibers in a module scale was carried out by long-distance and dynamic low-temperature (LDDLT) plasma flow, which is an environment-friendly surface chemical engineering method. For the module with a plasma inlet diameter of 15mm, contact angle variations along with fiber axial distance from plasma inlet revealed that the effective modification distance by LDDLT plasma flow was easily scaled up to about 80cm for purpose of industrial applications. The plasma-treated membrane module (PTMM) exhibited not only good chemical resistance in various solutions but also excellent antifouling property and hydrophilic stability. Moreover, the PTMM, which was dried at 25°C in vacuum after each filtration cycle, could still maintain high hydrophilicity after 7 water filtration cycles and storing over 90 days. Its average contact angle recovered by only 7°, and the steady water flux was about 30Lm^-2h^-1, far higher than the untreated ones.