Membrane Distillation (MD), a new and innovative membrane process, is mainly used in the treatment of saline aqueous solutions. Current research has not extensively studied the use of ceramic membranes in the MD process. Therefore, there is little insight in the application of ceramic membranes in MD. In order to study the effect of ceramic membranes in MD, hydrophobic TiO2-membranes (modified with Perfluoroalkylsilanes PFAS) were evaluated by Liquid Entry Pressure (LEP) measurements to gain in-formation about their hydrophobic characteristics. A selection of these membranes has been studied in two main MD processes (Direct Contact Membrane Distillation (DCMD) and Air Gap Membrane Dis-tillation (AGMD)). Selected results from these experiments were compared to the results of models, which can be found in current literature. All the membranes had sufficient LEP values to be tested in MD. The results of the experiment suggest that pore size is of vital importance to the LEP. A decrease of pore size from 0,4 μm to 0,1 μm was followed by an increase of LEP of 59 %. Furthermore, dissolved organic substances (PEG 1500) have a greater negative impact on the LEP than a feed temperature elevation from 20 to 60 °C.
The examination of the performance parameters of the different membranes, in MD, was implemented using Fraunhofer’s IKTS modified membrane extraction unit at Applikationszentrums Membrantech-nik. The permeation fluxes in DCMD were in range from 1,4 und 12,5 kg/(m²∙h). Fluxes in AGMD were recorded from 5,3 to 7,7 kg/(m²∙h). The experiment demonstrates that the effect of pore size on the flux depends on the applied driving force. Additionally, the results from DCMD (-89 %) showed a stronger reaction to the salt content (3 mol/L NaCl) of the feed solution in comparison to AGMD (-26 %). None of the membranes showed any sign of wetting during the experiments and salt retentions of at least 99,99 % were recorded using AGMD.