Nitto Electric Industrial Co., Ltd.

Pinoru Oil Mills Co.

Kentaro Tasaka

Akio Iwama

Yoshitaka Kazuse

Seiichi Tanahashi

Kaoru Nagano

Masaaki Kasai

Fujihiko Tsubone

Yutaka Isooka

A process for purification of crude glyceride oil compositions which comprises diluting a crude glyceride oil composition containing gum material and wax as main components of impurities with an organic solvent, bringing the diluted crude glyceride oil composition into contact with a semipermeable membrane composed of polyimide consisting essentially of a repeating unit represented by the general formula: ##STR1## wherein R.sup.1 represents a divalent organic group, under pressure to obtain a semipermeable membrane permeable liquid in which the gum material in the glyceride oil after removal of said organic solvent is 100 ppm or less, carrying out bleaching of the glyceride oil obtained from said semipermeable membrane permeable liquid with at least one kind of an adsorbent selected from the group consisting of clay, activated clay, activated carbon and bone black, and then carrying out deodorizing to obtain a purified glyceride oil.

Process for purification of crude glyceride oil compositions

A composite membrane and a process for producing the same are described. This composite membrane comprises a polyimide resin anisotropic membrane and a cross-linked silicone resin thin film formed on the anisotropic membrane, the anisotropic membrane comprising a dense surface layer and a porous layer continuously connected thereto and the polyimide resin consisting essentially of a repeating unit of the formula: ##STR1## wherein A and R.sup.1 are the same as defined hereinbefore. This composite membrane is useful for separation of organic solutions containing relatively small solutes of molecular weight of the order of 10 to 1,000 liquid/liquid separation, and concentration and separation of gases.

Composite membrane and process for producing the same

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Osaka, Japan

Kentaro Tasaka