Permeation and separation of organic solvents by porous inorganic membranes

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The purpose of the present study is to prepare porous ceramic membranes having various size of pore diameters and investigate the permeation performance of ceramic membranes.Ceramic membranes, which were prepared by sl-gel procedure, We have successfully prepared porous ceramic membranes from silica-zirconia composite colloidal sol solutions We have found that the transport mechanism of liquids through ceramic membrane having relatively large pores (larger than 70 nm) obeys the viscous flow mechanism, while the transport mechanism deviated from the viscous flow mechanism for membranes having smaller pore sizes. The reason was speculated that the affinity between permeating molecules and membrane surface and size plays an important role in determining permeation mechanism.Reverse osmosis experiments were carried out for several types of solutes in ethanol solutions. Solutes sued were n-hexane (CィイD26ィエD2HィイD214ィエD2, molecular weight 86), n-decane (CィイD210ィエD2HィイD222ィエD2, MW 142), and n-teradecane (CィイD214ィエD2HィイD230ィエD2, MW 142) as alkane solutes, and n-hexanol (CィイD26ィエD2HィイD213ィエD2OH, MW 102), n-octanol (CィイD28ィエD2HィイD217ィエD2OH, MW 130), n-decanol (CィイD210ィエD2HィイD221ィエD2OH, MW 1258) and alcohols. Solutes were rejected by porous membranes having pore size smaller than 1 nm. Rejection at 3 MPa and 60℃ ranges from 0.4 to 0.8, depending on the type of molecular weights. We have found that separation of organic molecular mixtures cane be separated by porous ceramic membrane in reverse osmosis. Analysis of transport mechanism suggested that diffusivity in pores was significantly affected by viscosity of solvents in pores.