Membrane Distillation (MD) has been gaining growing interest in the recent decade as a method for providing desalinated water from several water sources including high salinity water. The method has gained popularity due to the low required pressure, especially when the osmotic pressure makes membrane desalination such as RO uneconomic. In addition, MD has a high rejection of non-volatile compounds, less membrane fouling and higher flux retain. MD is a thermally driven process in which the vapor pressure gradient over the porous hydrophobic membrane leads to the transport of water vapor. To ensure an efficient driving force, the feed solution is continuously heated, leading to a substantial energy requirement. As most of the heat is not directly used due to a limited surface area and mass transport limitations, we suggest a novel approach which heats only the membrane-water interface through inductive heating (IH). Thus, significantly decreasing the required energy and increasing the permeate flux. Carbon nanotubes coated iron nanoparticles (CNT-Fe) membrane with high thermal conductivity are fabricated through sprayed on a PTFE base support (Fig.1 A) and the heating is done by exposing the CNT-Fe membranes with an iron loading of about 45 Wt. % (Fig.1 B) to a high-frequency magnetic field.<br/>Preliminary results show the ability of heating water directly on the surface of the membrane to a boiling temperature in a matter of seconds (Fig.1 C) by exposing the CNT-Fe membrane to an electromagnetic field at a fixed frequency (283 kHz). The heating ability was found to be related to the loading of CNT-Fe on the base support. In addition, permeate flux from the IH MD system was found to be higher than from a conventional MD system. Therefore, the high flux and low power consumption indicate the promising potential of IH membrane systems to improve MD processes and overcome their main energy limitations.

Inductive heating based membrane distillation: Role of CNT-Fe membranes

256th National Meeting (2018)

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