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Membranes used for membrane distillation (MD) inhibit passage of liquid water while allowing permeability for free water molecules and thus, for water vapour. [1] These membranes are made of hydrophobic synthetic material (e.g. PTFE, PVDF or PP) and offer pores with a standard diameter between 0.1 and 0.5 μm (3.9 × 10 −6 and 1.97 × 10 −5 ...
The liquid entry pressure (LEP) of a hydrophobic membrane is the pressure that must be applied to a dry membrane so that the liquid penetrates inside the membrane. LEP with the application in membrane distillation or pervaporation can be calculated as a first parameter to indicate how wettable a membrane is toward different liquid solutions.
The term pervaporation is a portmanteau of the two steps of the process: (a) permeation through the membrane by the permeate, then (b) its evaporation into the vapor phase. . This process is used by a number of industries for several different processes, including purification and analysis, due to its simplicity and in-line natu
Membrane distillation (MD) utilizes pressure difference from two sides of a microporous hydrophobic membrane. [21] [23] Fresh water can be extracted through four MD methods: Direct Contact (DCMD), Air Gap (AGMD), Sweeping Gas (SGMD) and Vacuum (VMD). [21] [23] An estimated water cost of $15/m 3 and $18/m 3 support medium-scale solar-MD plants.
An alternative method involves employing a hydrophobic membrane to prevent ions from entering the cell stack. This method combines a hydrophobic porous polytetrafluoroethylene (PTFE) waterproof breathable membrane with a self-dampening electrolyte, utilizing a hygroscopic sulfuric acid solution with a commercial alkaline electrolyzer to ...
The McCabe–Thiele method is a technique that is commonly employed in the field of chemical engineering to model the separation of two substances by a distillation column. [ 1 ] [ 2 ] [ 3 ] It uses the fact that the composition at each theoretical tray is completely determined by the mole fraction of one of the two components.
This difference is due to the different methods used to measure hydrophobicity. The method used to obtain the Janin and Rose et al. scales was to examine proteins with known 3-D structures and define the hydrophobic character as the tendency for a residue to be found inside of a protein rather than on its surface.
The membrane produced by this method has shown dramatic enhancements in flux and selectivity in various applications, such as sea water desalination (8,9), membrane extraction (10), water purification by the removal of volatile organics from water (11) and for micro scale membrane extraction for the analysis of water pollutants (12-14).