Flat Sheet Membranes for Membrane Distillation - Water and Wastewater - Water Filtration and Separation
Novamem provides specific membranes for membrane distillation. These membranes even perform if used under significant pressure. Thanks to the small pore sizes, it is also possible to perform membrane distillations with weaker hydrophilic-hydrophobic interaction. In other words: hydrophobic retention is much more effective, at smaller pore sizes as the contact survace is higher. Therefore, even much less polar liquids than water can be distilled via membrane distillation.
Details
Desalination
The distillation of salt water is possibly the most straightforward application of membrane distillation. The water is evaporated on the membrane and condensates on the permeation side. Thanks to the difference in temperature, there is also a difference in vapor pressure. Consequently, leading to distillation below the actual evaporation temperature.
Ethanol purification
Ethanol from water is purified with standard distillation processes until the azeotropic point (about 95%). From this point, standard distillation does not purify the mixture any further. However, a hydrophobic membrane leads to a demixing of the liquids. The less polar ethanol will be more likely on the interface between the liquid and the membrane. This interface will evaporate first, leading to a separation and consequently further purification of ethanol from water.
DCMD utilized a temperature difference between the feeding and permeation phase. Since the vapour pressure of all liquid increases at higher temperature, the heated feeding side has increased evaporation in comparison to the cooled permeation side. This method is the simplest, but requires a high repellent membrane to both, the feeding mixture as well as the distillate. Also it requires high volume of distillate since the distillate is also the cooling liquid. Only highly repellent membranes are feasible for this process. Please contact us with details of your desired distillation for our recommendation.
This method is most straight forward, as the liquid on the feeding side of the membrane is distilled by a vacuum on the permeation side of the membrane. Usually, differential pressure is 1 bar, unless the liquid faces additional pressure. The feeding liquid can be heated for increased distillation flux. This method benefits a very high flux, but requires significant energy input. From the applied vacuum, the permeate is then liquified in a condenser. Novamem has a wide range of possible membranes for this method. Please contact us below, if you have an inquiry.
SGMD is similar to Vacuum MD, but instead of a vacuum, it utilizes a controlled gas phase. While having a lower pressure difference and thus less flux, it is less energy consuming. Also certain chemicals might decompose in very low pressure. The permeate is then liquified in a condenser from the gas mixture. Novamem has a wide range of possible membranes for this method. Please contact us below, if you have an inquiry for membranes.
The Air Gap method requires little energy but is similar to the Sweeping Gas method. Instead of a sweeping gas flow, permeate enters an air gap, which is directly cooled via a condensation plate. The product is then immediately condensed and removed. This is the most simple method without mixing the permeate with the cooling liquid.
