molecular distillation systems

Membrane distillation is a trend in recent years a new membrane separation technology. It is the use of hydrophobic microporous membrane separation of aqueous solution containing non-volatile solute a membrane technology. Due to molecular distillation systems the effect of surface tension of the water, the pressure of liquid water can't through the membrane pores, while water vapor can be. When the film has certain temperature difference on both sides, because of the difference of vapour pressure, water vapor molecules through the pores on the other side the cooling down, make the solution gradually enrichment. Can make full use of the process plant hot or cheap energy such as solar energy, and process automation, simple equipment, is becoming a kind of separation technology of practical significance.

Membrane distillation (be distillation, MD for short) is a kind of used hydrophobic microporous membrane in membrane on both sides of the steam pressure difference driving force for mass transfer of membrane separation process, can be used in the distillation desalination of water, aqueous solution to remove volatile substances. For example when the different temperature of aqueous solution is hydrophobic microporous membrane separating, due to the hydrophobic membrane, on both sides of the aqueous solution into the other side are not through the membrane pores, but because of the warm side aqueous solution and membrane water vapor pressure is higher than the cold side of the interface, water vapor will be from the warm side into the cold side through the membrane pores and condensation, the thin film distillation evaporation of conventional distillation, mass transfer, condensation process is very similar, so called the membrane distillation process.

Shortage of fresh water resources become a big problem in today's society, is the source of fresh water desalination. From the seawater or brackish water for fresh water of the main methods are: electrodialysis method and evaporation method, multi-stage distillation and reverse osmosis, etc. Has developed rapidly in recent years with membrane distillation method of membrane distillation technology in the application of the seawater desalination succeeded, is expected to become a new method of preparing a cheap and efficient fresh water. Using industrial use of water waste heat or use industrial waste heat winterization filtration heating water by membrane distillation desalination, has low cost, simple equipment, easy operation, and low energy consumption, make the membrane distillation technology in many desalination project has a certain competitiveness.

Due to the hydrophobic membrane, in principle only allow water vapor through the pores, thus can get very pure water. After processed by vacuum membrane distillation of tap water, the water quality reach the microelectronics industry with high purity water level 3 and medical injection water standards. Especially the recent new high-throughput inorganic membrane and successful development of organic-inorganic hybrid membranes with membrane distillation preparation industry means of ultrapure water have become a great commercial potential.