关键词: 膜蒸馏, 脱盐, 分离, 膜润湿, 抗润湿措施, 膜

Abstract:

Membrane distillation (MD) is suitable for small scale production of fresh water in remote areas with the advantages of high salt rejection rate, nearly atmosphere operation, utilization of the solar energy and so on. However, membrane wetting affects the operation stability of MD device which is a major factor of restricting the application of MD desalination. The evaluation methods of MD membrane wetting, including the measurement of liquid entry pressure (LEP), critical membrane pore wetting depth and in-situ observation of membrane wetting process and so on, were introduced firstly. Then, the influenced factors on membrane wetting such as membrane fouling, MD operating variables, various MD configurations and distinct scaling behaviors were discussed in details. The inhibition measures of membrane wetting were analyzed from several aspects, such as anti-fouling, enhancing flux, suitable membrane cleaning period, physical methods and improving the performances of membrane. Finally, the behaviors of membrane wetting during the course of the long-term MD desalination operation were also introduced. It was pointed out that photocatalytic composite membrane with self-cleaning property, omniphobic membrane and Janus membranes were of great potential to prevent membrane wetting and probably applied in anti-wetting MD membrane. The studies in this paper will be helpful to predict and control MD membrane wetting during desalination.

Key words: membrane distillation, desalination, separation, membrane wetting, anti-wetting strategy, membrane