JPH0716440A - Water-organic solvent separating membrane - Google Patents

Abstract

PURPOSE:To obtain a water-org. solvent separating membrane having high separating performance and high permeability in a well-balanced state by using polyurethane represented by a specified structural formula. CONSTITUTION:This water-org. solvent separating membrane is made of polyurethane represented by the general formula [where R1 is a residue of polyisocyanate, R2 is a residue of polyol and (n) is a natural number]. Since the polyurethane is obtd. by bringing a polyisocyanate compd. having a hydrophobic structure and a polyol compd. into a polyaddition reaction, this separating membrane exhibits high permselectivity by hydrophobic interaction with an org. solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-organic solvent separation membrane for efficiently permeating and separating an organic solvent dissolved in water to purify water or concentrate and recover the organic solvent.

[0002]

2. Description of the Related Art Generally, a distillation method is used for separating a specific compound from a liquid mixture. However, it is difficult to separate azeotropic mixtures, near-boiling mixtures, or thermally labile compounds from such mixtures in such liquid mixtures, even using distillation methods. Further, it is also difficult to separate the organic solvent from water such as industrial waste water in which the organic solvent is present in an amount of several%.

For example, phenol-containing wastewater is treated by extracting phenol with benzene or the like and then distilling or incinerating it, blowing air into the wastewater and evaporating it into the atmosphere, or diluting with water and treating with microorganisms. Etc. are usually adopted.

Therefore, in order to efficiently perform such separation, a method using a membrane has been conventionally studied. One of them is the pervaporation method (pervaporation method).
Many reports are known as an effective method for separating a mixture which is difficult by the above-mentioned distillation.

The reported example is mainly a dehydration membrane of an organic solvent containing a trace amount of water, for example, a water selective permeable membrane used for dehydration of an azeotropic mixture of ethanol, and a dehydration plant is also put into practical use.

On the other hand, on the other hand, an organic solvent selective permeable membrane for separating an organic solvent from water containing an organic solvent of about several% or a mixture of two or more kinds of organic solvents has been reported.
Membranes satisfying high separation and permeability have not been reported.
Examining the membranes reported to date, the membrane performance is not well balanced, such as high permeability and low separability, or high separability and low permeability. All of them are insufficient as the treatment capacity of the membrane.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above technical problems and to provide a well-balanced water-organic solvent separation membrane having both high separability and permeability.

[0008]

In order to achieve the above object, the water-organic solvent separation membrane according to claim 1 has the general formula

[0009]

[Chemical 2]

(Wherein R ₁ represents a polyisocyanate residue, R ₂ represents a polyol residue, and n represents a natural number).

Here, R is a polyisocyanate residue, and a typical structure thereof is the following structure (formula 3 to formula 8,
Chemical formula 15 to chemical formula 26) can be mentioned.

[0012]

[Chemical 3]

In the above Chemical Formula 3, n is a natural number of 1-18.

[0014]

[Chemical 4]

[0015]

[Chemical 5]

[0016]

[Chemical 6]

[0017]

[Chemical 7]

[0018]

[Chemical 8]

Here, R _{3 in} Chemical formula 8 is the following Chemical formula 9 to Chemical formula 1
It is either 2.

[0020]

[Chemical 9]

[0021]

[Chemical 10]

[0022]

[Chemical 11]

[0023]

[Chemical 12]

R ₄ in the above Chemical Formula 8 is the following Chemical Formula 13
Alternatively,

[0025]

[Chemical 13]

[0026]

[Chemical 14]

[0027]

[Chemical 15]

[0028]

[Chemical 16]

Here, R ₄ in the chemical formula 16 is R in the chemical formula 8 above.
Similar to ₄ .

[0030]

[Chemical 17]

[0031]

[Chemical 18]

[0032]

[Chemical 19]

[0033]

[Chemical 20]

[0034]

[Chemical 21]

[0035] Here, n is 2, 3 or 4 in Chemical Formula 21, R ₄ is the same as R ₄ in the chemical formula 8.

[0036]

[Chemical formula 22]

[0037]

[Chemical formula 23]

[0038]

[Chemical formula 24]

[0039]

[Chemical 25]

[0040]

[Chemical formula 26]

R 2 in the above Chemical Formula ₂ is a polyol residue, and its typical structure is the following structure (Chemical Formula 27 to Chemical Formula 3).
1) can be mentioned.

[0042]

[Chemical 27]

Here, n in Chemical formula 27 is a natural number of 1 to 12.

[0044]

[Chemical 28]

[0045]

[Chemical 29]

Here, m in Chemical formula 29 is 1 or 2, n is a natural number of 3 to 50, and R ₅ is the same as R _{4 in} Chemical formula 8 above.

[0047]

[Chemical 30]

Here, n in the chemical formula 30 is a natural number of 3 to 50.

[0049]

[Chemical 31]

Here, n in the chemical formula 31 is a natural number of 3 to 50, R ₆ is one of the following chemical formulas 32 to 41,
R ₇ is any of the following chemical formulas 42 to 51.

[0051]

[Chemical 32]

[0052]

[Chemical 33]

[0053]

[Chemical 34]

[0054]

[Chemical 35]

[0055]

[Chemical 36]

[0056]

[Chemical 37]

[0057]

[Chemical 38]

[0058]

[Chemical Formula 39]

[0059]

[Chemical 40]

[0060]

[Chemical 41]

[0061]

[Chemical 42]

[0062]

[Chemical 43]

[0063]

[Chemical 44]

[0064]

[Chemical formula 45]

[0065]

[Chemical formula 46]

[0066]

[Chemical 47]

[0067]

[Chemical 48]

[0068]

[Chemical 49]

[0069]

[Chemical 50]

[0070]

[Chemical 51]

Preparation of polyurethane by polyaddition reaction is carried out as follows. Basically, the isocyanate compound and the polyol compound are mixed and stirred so that the number of functional groups becomes 1: 1. Here, if necessary, a solvent (eg, chloroform, ethyl acetate, methyl ethyl ketone, etc.) that does not have active hydrogen with which an isocyanate group can react and a catalyst (eg, tin chloride, organotin compound, tertiary amine, etc.) are used. In addition, the reaction can be carried out. When the durability of the film such as thermal stability is required, 1,4-butanediol, which is generally used as a chain extender,
1,6-hexanediol, 1,6-hexamethylenediol, and a tri- or more functional polyisocyanate compound,
Alternatively, the polyaddition reaction may be carried out by adding the polyol compound to a few% (% by weight) of the total polyisocyanate polyol component.

Examples of the polyfunctional polyisocyanate include the compounds of the following chemical formulas 52 and 55 to 63.

[0073]

[Chemical 52]

Here, R ₈ in the chemical formula 52 is the following chemical formula 53, chemical formula 5
One of four.

[0075]

[Chemical 53]

[0076]

[Chemical 54]

[0077]

[Chemical 55]

[0078]

[Chemical 56]

[0079]

[Chemical 57]

[0080]

[Chemical 58]

[0081]

[Chemical 59]

[0082]

[Chemical 60]

[0083]

[Chemical formula 61]

[0084]

[Chemical formula 62]

[0085]

[Chemical formula 63]

As the polyfunctional polyol compound, for example, the compounds of the following chemical formulas 64 to 69 can be mentioned.

[0087]

[Chemical 64]

[0088]

[Chemical 65]

[0089]

[Chemical formula 66]

[0090]

[Chemical formula 67]

[0091]

[Chemical 68]

[0092]

[Chemical 69]

The polyurethane thus obtained is reprecipitated and purified by using these non-solvents if necessary, dried and then dissolved in a suitable solvent. This solution is formed on the support membrane directly or on a release-treated film by a method such as coating, and then dried. Further, when the film is formed on the release-treated film, the polyurethane layer is transferred onto the support film. Furthermore, a support film is laminated on the surface on which the support film is not laminated,
The polyurethane layer may be sandwiched between two supports to form a composite film. Further, it is possible to obtain a composite membrane having a plurality of support membranes and polyurethane layers by repeating these operations. When the swelling of the membrane due to the solution to be separated is large, the membrane may be formed by adding a crosslinking agent at the time of forming the polyurethane to improve the strength of the membrane. Further, the polyurethane prepared by the polyaddition reaction may be processed into a flat film, a hollow fiber or the like by using a method such as melt film formation, wet spinning or dry spinning.

A pervaporation method (permeation method) is used as a method for permeating and separating an organic solvent from a water-organic solvent mixture using such a composite membrane. This method is a known method, in which one of the membranes is supplied with a solution to be separated, and the other is depressurized or swept with a gas not related to the permeation component,
The permeated components are collected and separated using a cooling trap or the like.

The degree of separation of each component is generally expressed as follows using the separation coefficient (α).

[0096]

[Equation 1]

Α1 / 2 is a separation coefficient when the component 1 is a component to be transmitted / separated. Where X ₁ , X
₂ : The concentrations of component 1 and component 2 in the feed liquid, Y ₁ and Y ₂ : the concentrations of component 1 and component 2 in the permeate liquid.

Further, Flux (flux, permeation flow velocity) indicating the permeation amount of the membrane is expressed by the following equation.

[0099]

[Equation 2]

Furthermore, the flux of each component can be calculated from the concentrations of component 1 and component 2 in the permeate and flux.

It can be said that the performance as a separation membrane is better when both α and Flux are high and well balanced, that is, the product of these is large.

[0102]

The separation membrane of the present invention uses a polyisocyanate and a polyol compound having a hydrophobic structure such as an aliphatic, aromatic or alicyclic hydrocarbon structure, and utilizes its hydrophobic interaction with an organic solvent. However, high selective permeability can be obtained. Further, with respect to a weakly acidic organic solvent such as phenol, acid-base interaction occurs due to the basicity of the urethane bond, and high selective permeability with respect to the membrane can be obtained.

Therefore, the separation membrane of the present invention can be used in various water
Organic solvent mixtures, for example, alcohols such as methanol, ethanol, propyl alcohol, ethyl acetate, esters such as butyl acetate, halogenated hydrocarbons such as trichloroethane and tetrachloroethylene, hydrocarbons such as toluene, acetone, ketones such as methyl ethyl ketone,
Among amines such as N, N-dimethylformamide, etc., it is effective for separating an aqueous solution containing one or more kinds, and is particularly effective for permeation separation of water-phenol.

As the separation method, a vapor permeation method and a perstraction method can be used in addition to the pervaporation method.

[0105]

EXAMPLES The present invention will be described more specifically by showing examples below.

1) Example 1 Hexamethylene diisocyanate (hereinafter HMDI) and polytetramethylene glycol (weight average molecular weight 2900) (hereinafter PTMG (290
0)) was mixed and chloroform was added to make a 80 wt% solution. Stannous chloride in ethyl acetate (1% by weight)
Was added in a catalytic amount, and the mixture was stirred overnight at room temperature. 2 this solution
The mixture was diluted with chloroform to 5% by weight, and HMDI was added as a cross-linking agent so that the mole fraction was 25% of all urethane bonds, and the mixture was sufficiently stirred.

This is coated on a polyethylene terephthalate (hereinafter PET) film which has been subjected to a release treatment, and the temperature is 100 ° C.
And dried for 5 minutes. After drying, a support of a polypropylene (hereinafter referred to as PP) porous film having a thickness of 25 μm was attached, the PET film was peeled off, and a polyurethane film having a thickness of 10.8 μm was formed on the support. Furthermore, PP on the polyurethane film
The porous membrane was used as a laminated composite separation membrane.

Next, this separation membrane was attached to a pervaporation permeation measuring apparatus, and 1 liter of a 1% by weight phenol aqueous solution was supplied into the upper chamber using a circulation pump, and the measurement temperature was 6
The permeation measurement was performed at 0 ° C. under a reduced pressure of 2.5 mmHg in the lower chamber. The results are shown in Table-1.

2) Example 2 The PTMG (2900) of Example 1 was replaced with the PTMG (100
Film formation and permeation measurement were carried out in the same manner except that it was set to 0). The results are shown in Table-1.

3) Example 3 The PTMG (2900) of Example 1 was replaced with the PTMG (650).
Film formation and permeation measurement were performed in the same manner except that the above was used.
The results are shown in Table-1.

4) Example 4 Film formation and permeation measurement were carried out by the same method except that HMDI of Example 1 was changed to 2,4-toluene diisocyanate (hereinafter referred to as TDI). The results are shown in Table-1.

5) Example 5 A film was formed by the same method except that the HMDI of Example 1 was changed to 1,12-diisocyanatododecane (hereinafter DID).
Transmission measurements were performed. The results are shown in Table-1.

6) Example 6 Film formation and permeation measurement were carried out by the same method except that the HMDI of Example 1 was changed to isophorone diisocyanate (hereinafter IPDI). The results are shown in Table-1.

7) Example 7 Film formation and permeation measurement were carried out by the same method except that HMDI of Example 1 was changed to 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI). The results are shown in Table-1.

8) Example 8 The PTMG (2900) of Example 1 was converted into polycaprolactone diol (weight average molecular weight 3000) (hereinafter PCL (3
000)) was performed, and film formation and permeation measurement were performed in the same manner. The results are shown in Table-1.

9) Example 9 Using the membrane of Example 1, 0.3 liter of a 1 wt% aqueous solution of ethanol was supplied instead of 1 liter of a 1 wt% aqueous solution of phenol. The measurement was performed. The results are shown in Table-2.

10) Example 10 Using the membrane of Example 1, 0.3 liter of 1% by weight aqueous solution of acetone was supplied instead of 1 liter of 1% by weight aqueous solution of phenol, and other conditions were the same as in Example 1. The measurement was performed. The results are shown in Table-2.

11) Example 11 Using the membrane of Example 1, 0.3 liter of a 1 wt% aqueous solution of ethyl acetate was supplied instead of 1 liter of a 1 wt% aqueous solution of phenol, and other conditions were the same as in Example 1. Transmission measurements were performed. The results are shown in Table-2.

12) Example 12 Using the membrane of Example 1, 0.3 liter of a 0.15 wt% aqueous solution of 1,1,2-trichloroethane was supplied in place of 1 liter of a 1 wt% aqueous solution of phenol under other conditions. The transmission measurement was performed in the same manner as in Example 1. The results are shown in Table-2.

13) Example 13 Using the membrane of Example 1, 0.3 liter of 0.015 wt% aqueous solution of toluene was supplied instead of 1 liter of 1 wt% aqueous solution of phenol, and other conditions were the same as in Example 1. Then, the transmission measurement was performed. The results are shown in Table-2.

Comparative Example 1) Comparative Example 1 Permeation measurement was carried out in the same manner as in Example 1 except that the nylon 6 composite film was used as the polyurethane composite film. The results are shown in Table-1
Shown in.

2) Comparative Example 2 Permeation measurement was performed in the same manner as in Example 1 except that the polyurethane composite film was a polyethylene composite film. Table of results
Shown in 1.

3) Comparative Example 3 Permeation measurement was carried out in the same manner as in Example 1 except that the polyurethane composite film was a polydimethylsiloxane composite film.
The results are shown in Table-1.

[0124]

[Table 1]

[0125]

[Table 2]

[0126]

As described above, the present invention is a separation membrane made of polyurethane obtained by a polyaddition reaction from a polyisocyanate compound having a hydrophobic structure and a polyol compound. It exhibits high selective permeability due to interaction. In addition, selective permeability can be obtained for weakly acidic organic solvents such as phenol by acid-base interaction due to the basicity of the urethane bond. Therefore, when the separation membrane of the present invention is used for separating an organic solvent from water containing a small amount of the organic solvent, only the organic solvent can be selectively separated efficiently.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 13, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0071

[Correction method] Change

[Correction content]

Preparation of polyurethane by polyaddition reaction is carried out as follows. Basically, the isocyanate compound and the polyol compound are mixed and stirred so that the number of functional groups becomes 1: 1. Here, if necessary, a solvent (eg, chloroform, ethyl acetate, methyl ethyl ketone, etc.) that does not have active hydrogen with which an isocyanate group can react and a catalyst (eg, tin chloride, organotin compound, tertiary amine, etc.) are used. In addition, the reaction can be carried out. When the durability of the film such as thermal stability is required, 1,4-butanediol, which is generally used as a chain extender,
1,6-hexanediol, 1,6-hexamethylenediol, and a tri- or more functional polyisocyanate compound,
The polyaddition reaction may be carried out by adding a polyol compound and a polyol compound of several% (% by weight) of the total polyisocyanate and the polyol component.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0079

[Correction method] Change

[Correction content]

[0079]

[Chemical 57]

Claims (1)

[Claims] 1. A general formula: (In the formula, R ₁ represents a polyisocyanate residue, R ₂ represents a polyol residue, and n represents a natural number.) A water-organic solvent separation membrane comprising a polyurethane.