JPS61271006A - Ultrafiltration membrane - Google Patents

Abstract

PURPOSE:To obtain ultrafiltration membrane having fouling resistance by impregnating high molecular porous membrance with anionic dimolecular film of lipid. CONSTITUTION:After immersing a porous membrane comprising polysulfone etc. in a soln. dissolving a lipid of anionic dialkyl phosphate. etc., the membrane is washed with water. Thus, an ultrafiltration membrane holding a lipid in the form of dimolecular structure in the pores of the porous membrane is obtd. Since negative charge is given to the membrane, deposition of filtered substances to the surface of the membrane is prevented during filtration of negatively charged emulsified liquid, etc. Amphoteric electroyte such as protein, etc. can be filtered at above the isoelectric point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultraporous membrane. More specifically, the present invention relates to a stain-resistant ultrafiltration membrane.

[Conventional technology]

In oil-water separation using an ultrafiltration membrane, filtration substances adhere over time, resulting in a decrease in water permeation rate. In general, mechanical cleaning using balls, air bubbles, water flow, etc., chemical cleaning using chemicals, and backwashing are used to restore water permeation. However, with such means, the oral filtration is interrupted during washing, and the overall oral filtration efficiency is reduced. It is also necessary to treat the liquid produced by cleaning.

[Problem that the invention seeks to solve]

Due to these problems, recent research has been conducted to prevent adhesion to the membrane surface by modifying the membrane itself to create an s-leaving group and creating a charge with the same sign as that of the oral product. It has become to.

As a result of conducting studies from this viewpoint, the present inventor was able to obtain a stain-resistant ultrafiltration membrane by impregnating a porous polymer membrane with a specific anionic membrane.

[Means for Solving the Problems] and [Operation] Accordingly, the present invention relates to a stain-resistant ultra-permeable membrane, which comprises a porous polymer membrane containing an anionic lipid 2. It is impregnated with a molecular membrane.

Porous polymeric membranes include porous membrane materials of various polymeric materials such as polysulfone, polyvinylidene fluoride, aromatic polyamide, polypropylene, cellulose acetate, and polycarbonate, as long as they have a pore size of about 0.001 to 1 μm. A material with a pore size that can form an external membrane is used.

As the lipid impregnated into these porous membrane materials, anionic phosphoric acid dialkyl esters, sulfosuccinic acid dialkyl esters, etc. are used. These lipids can be prepared by dissolving them in linear or alicyclic hydrocarbon solvents such as dodecane, octane, hexane, cyclohexane, etc.
By impregnating it into a porous membrane, it assumes a bilayer membrane structure and is retained in the micropores of the membrane.

〔Effect of the invention〕

By impregnating an anionic lipid bilayer membrane into the micropores of a porous polymer membrane and imparting a negative charge to the membrane, it is effective in passing negatively charged emulsions and the like.

Furthermore, ampholytes such as proteins can also be used under conditions where they become negative, that is, at equal or higher concentrations. Furthermore,
By impregnating the anionic lipid with a neatly oriented bilayer membrane structure, the charge density increases and the mouth-cleaning effect is further enhanced.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 15% by weight of polysulfone (UCC product P-1700), polyvinylpyrrolidone (molecular weight approximately 750,000)
Dimethylformamide solutions each containing 1% by weight were cast on a glass plate using a 0.2 mm thick spacer, and coagulated by a dry-wet method using water as a coagulation bath, resulting in a pure water permeability coefficient of 10.2 aj/ aLhr-kg/aJ
A polysulfone porous membrane (thickness approximately 0.1 ms+) with a molecular weight cut-off of 20,000 was obtained.

Separately, phosphorus oxychloride and three equivalents of dodecyl alcohol were refluxed in benzene, and after reaction for 20 hours, the mixture was allowed to cool, treated with an alkali, and recrystallized to obtain a dialkyl phosphate ester of CtZ.

The polysulfone porous membrane is immersed in this 3% dodecane solution of lipid at 60° C. for 10 minutes. Thereafter, the liquid temperature was allowed to reach room temperature, and then the porous membrane was taken out and washed with water to obtain the desired ultrafiltration membrane.

In order to examine the permeability of the obtained ultrafiltration membrane, a permeation test was conducted using a continuous flat membrane cell.

An emulsified oil cutting agent (Yushiro Chemical Products Nijiroken EC-5 dispersed in 150 times the amount of water) was used as the mouth fluid, and the water permeation amount at the initial stage and after 150 hours and the ratio thereof were determined.

Initial water permeability (A) 6.3aJ/a#-hr-
kg/aJ Water permeability after 150 hours (B) 4.2a
#/a#-hr-kg/a# same ratio (B/AX100)
66.7% Comparative Example A similar permeation test was conducted on the polysulfone porous membrane itself used in the example.

Initial water permeability (A) 7.2a (/a&-hr-
kg/aJ Water permeability after 150 hours (B) 2.9 cd
/a#-hr-kg/aJ same ratio (B/AX100)
1 from the results of Examples and Comparative Examples of 40.3% or more
Although the ultrafiltration membrane according to the present invention has a rather low initial water permeation rate.

The decrease in water permeability due to passage of time is considerably suppressed,
It is found that it has excellent stain resistance. In addition, in both Examples and Comparative Examples, the permeated liquid showed an exclusion rate of 98% or more when measured for total organic carbon content (TOC).

Claims (1)

[Claims] 1. An ultrafiltration membrane formed by impregnating a porous polymer membrane with an anionic lipid bilayer membrane. 2. The ultrafiltration membrane according to claim 1, wherein the lipid is dialkyl phosphate. 3. The ultrafiltration membrane according to claim 1, wherein the lipid is a dialkyl sulfosuccinate.