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Fabrication of a full-ceramic hydrophobic membrane for water desalination

Menke, R. (2015) Fabrication of a full-ceramic hydrophobic membrane for water desalination.

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Abstract:In this work a full-ceramic membrane, suitable for water desalination by means of Membrane Distillation (MD), was developed. A Si3N4 membrane was fabricated using the phase-inversion tape casting method, which resulted in a thin skin layer with small pores at the top, finger-like micro channels that were almost back-through in the middle and a spongy layer at the bottom. The surface properties of the membrane were changed from hydrophilic to hydrophobic by pyrolysis of PDMS which introduced methyl groups on the surface. The obtained water contact angle was 117°. During sintering the membranes were immersed in a powder bed and pieces of powder stuck to the membrane, which were removed by sandpaper. This treatment damaged the skin layer and bigger pores were exposed, which caused the Liquid Entry Pressure to be lower than expected. Other performance tests such as assessing the salt rejection and the gas and water vapour flux were conducted. The salt rejection was measured using a NaCl solution and a value of 99.8% was obtained, which is well comparable with literature values for various desalination membranes in MD. Due to the wrinkled shape of the membranes the spongy layer could not be taken off completely, which resulted in higher mass-transfer resistance. This influenced the water vapour flux, which was much lower than reported literature values. The gas permeability was however not hindered by this layer.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:35 chemistry
Programme:Chemical Engineering BSc (56960)
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