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Detection and Understanding of Wetting Mechanisms in Vacuum Membrane Distillation Applied to Desalination of Seawater

Abstract : With an ever-increasing population and the growing disparity in potable water resource, humanity has turned its attention to the oceans for its potable water needs. To overcome the current limitations in current desalination technologies, membrane distillation (MD) is actively being developed. The interest of MD for seawater desalination was established in the last decades but today the risk of membrane wetting is one of the major barrier for industrial implementation of MD. Under the framework of the ANR project “WETMEM”, the issue of this thesis was to develop tools for better understanding wetting mechanisms in vacuum membrane distillation. Several fabricated (WETMEM partners) and commercial membranes were studied to understand the influences of membrane properties on wettability. Therefore, a definition and classification on wetting were formulated. After that two wetting indicators were developed using scanning electron microscopy and X-ray dispersion spectroscopy under a method called “Detection of Dissolved Tracer Intrusion”. A proof of concept was provided with various wetting mechanisms visualized and interpreted. These ex-situ indicators were used with wettability tools (Contact Angle, Liquid Entry Pressure) to understand the influence of temperature (35-50°C), salinity (22-310 g/L NaCl sol.) and flow rate (400 – 4000 Re) on wetting and wettability of a PVDF membrane under vacuum membrane distillation. Indeed, it was found that salinity has a greater impact on wetting than the other operating parameters. Additionally, a proof of concept was provided for non-invasive in-situ optical method for visualizing wetting in membrane distillation. Progression of in-situ wetting visualization was validated at different scales for various saline solutions and seawaters.
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Submitted on : Thursday, August 20, 2020 - 10:59:57 AM
Last modification on : Friday, August 21, 2020 - 3:28:10 AM


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  • HAL Id : tel-02918208, version 1


Paul Jacob. Detection and Understanding of Wetting Mechanisms in Vacuum Membrane Distillation Applied to Desalination of Seawater. Chemical and Process Engineering. INSA de Toulouse, 2018. English. ⟨NNT : 2018ISAT0036⟩. ⟨tel-02918208⟩



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