JPS60209291A - Separation of water-soluble organic compound - Google Patents

Abstract

PURPOSE:To improve the separation efficiency and the permeation performance by adding the metallic salt of a phosphorus compd. to the mixture of water and water-soluble organic components in the osmosis-vaporization separation of an aq. soln. of organic compds. CONSTITUTION:The metallic salt of a phosphorus compd. such as KH2PO4 and K2HPO4 is added to the liquid mixture of water and water-soluble organic compds. such as ethanol. The liquid mixture is added into the cell of an osmosis- vaporization apparatus wherein a high molecular membrane such as a polydimethylsiloxane membrane is set, and allowed to stand in a thermostat. The opposite side of the liquid mixture is sucked by a vacuum pump, and the substance which permeates the membrane is taken out in a gaseous state.

Description

Detailed Description of the Invention The present invention relates to a method for selectively separating water-soluble organic compounds from a mixed liquid of water/water-soluble organic compounds by pervaporation using a synthetic polymer membrane. Distillation has been known for a long time as a method for obtaining water-soluble organic compounds from a mixed organic compound liquid, and is generally widely used. However, when obtaining an organic compound from an aqueous solution of an organic compound with a low concentration or when obtaining an organic compound from a mixed liquid of an organic compound/water having an azeotropic composition, there is a drawback that a large amount of energy is consumed.

A method to overcome this difficulty is to pass through a synthetic polymer membrane. The material of the polymer membrane used in this immersion flK conversion method is selected from one that has an affinity for the component to be permeated.

As an example of the method with membrane sa(8)SL? ? (1
983) S and ;r, M@m, +301 , 10,15
3 (19ajl), using silicone rubber, ethanol/water, isoprop p/-/water m mixture to ethanol,
It has been reported that isopropanol can be isolated. However, it has the disadvantage of a low coefficient. Improved the above method71
'Is there a method of adding salt to the mixed liquid to improve efficiency? -1! It is described in the $91301 publication. In this method, lithium chloride monochloride V is added to the mixed liquid.
Inorganic salts such as magnesium chloride 1M aluminum chloride and sodium acetate 1! It is stated that by adding a fatty acid salt such as potassium chloride, it is possible to improve the separation efficiency and the amount of permeation. but,
There is no mention of differences between metal salt types.

The present inventors have intensively investigated the effect of adding various metal chlorides of the MJ group to an aqueous solution system in the permeation of organic compound water Q using a polymer membrane. It was discovered that a certain anion affects the separation membrane rate and permeation performance, leading to the following invention.

That is, this is a method for separating water-soluble organic compounds in which a metal salt of a phosphorus compound is made to exist in an SM mixture in a pervaporation method that separates an organic component from a mixture consisting of water and a water-soluble organic component. The metal salt is selected from alkali metals in which 1 metal is lithium, 1 potassium, syv, cesium, and the ligand is phosphorus, f111.
Phosphite, phosphone! ! These are gold salts consisting of 1 phosphite, 1 phosphite, 1 phosphite, 1 phosphinic acid, and their derivatives 4j11. Specifically, to Rin #I) Mizurin Iriki,
) Lium 1 hydrogen phosphate to ) Sodium 1 phosphate to Barium 1 Phosphorus #! (to) potassium hydrogen 1 to hydrogen phosphate) to potassium 1 phosphate (to potassium phosphate 1 to hydrogen phosphite)
Sodium, hydrogen phosphite, potassium, and other phosphites are mentioned. Among them, Rin 1! (→Potassium hydrogen monophosphate←) Potassium is particularly preferred.

It is also possible to make a polymer compound having these compounds in its side chain exist both in the mixed liquid and in both the mixed liquid and the polymer membrane.

There are no particular restrictions on the method of adding salt, but inorganic
! 4 When adding the salt to the mixed solution, it is preferable to dissolve the metal salt in the mixed solution in advance. The salt concentration at this time is not particularly limited, but a high salt concentration is not preferred in practice. If the salt concentration is low, the effect of salt addition decreases, so 0.1-
J! A range of Ovt% is preferred. This is not the case when using polymeric metal salts as additives. ◎ The membrane used for separation is preferably a membrane that has excellent affinity with organic compounds. 1 Polyester 1 Polyamide 1 Polyurethane 1 Polyimide 1 Polyolefin Polyvinyl alcohol 1 Epoxy resin cured product - 7-ru4-th yarn polymer compound ~ Polysulfone 1 Silicone polymer compound 1 Polyvinyl alcohol, polyacrylic 12 Nisilyl 1 Polymethacrylic acid ester 1 Homopolymer and a film obtained from a copolymer thereof It can be appropriately selected depending on the components of the mixed solution.

The thickness of the above-mentioned separation membrane is not particularly set, but 1 and preferably 0.1
~160μ. If the membrane has sufficient strength, it is practically preferable to make it as thin as possible, as this increases the amount of permeation. The shape of the membrane may be a flat membrane, for example, a cylindrical shape or a hollow fiber shape with a large membrane surface area r'g:'.

The water/water-soluble organic compound mixed liquid in the present invention is a liquid in which an organic compound is uniformly dissolved in water, and includes the following. Examples of organic compounds include alcohol (methanol 1 ethanol 1 pudenpanol, impulpanol, etc.) 1 organic acid (gil!! 1 acetic acid 1 pionic acid, butyric acid, etc.) Organic acid ester (acetic acid methyl 1 ethyl acetate) Such)
1 Ketones (acetone, 1 methyl ethyl ketone, etc.) cyclic ethers (dioxane, 1 tetrahydrofuran, etc.) Compounds include - The above compounds are in the mixed liquid! ! 4
It is possible even if it contains Class 11i or higher.

Separation of the water-soluble organic compound from the water/water-soluble organic compound mixture column of the present invention is carried out using a conventional pervaporation method.
The pressure on the opposite side of the separation membrane that does not come into contact with the mixed liquid must be lower than the pressure on the side that does come into contact with the mixed liquid.

The larger the pressure difference, the more effective it is, but preferably 0.1 to 1 oossH9. Both separation efficiency and permeation rate are improved by evaporating the substance that has passed through the membrane on the low-pressure side and taking it out in gaseous form. Therefore, it is preferable to keep the pressure on the low-pressure side lower than the vapor pressure of the substance that is passing through the membrane. Methods for keeping the pressure low include reducing the pressure by placing it in a vacuum 81 or keeping it at a low vapor pressure by flowing an inert gas 17.

□1: The applicable temperature range in the separation method of the present invention may be within a range in which the mixed liquid does not undergo terrestrial dissolution or the membrane is denatured, and is preferably 0 to 100'O.

- The qualitative and quantitative effects obtained by the present invention will be described below based on Examples and Comparative Examples; however, the scope of the present invention is not limited thereto.

Experiments Pervaporation Experimental Method The following experiment was conducted under atmospheric pressure on the supply side of the water/water-soluble organic compound mixture and under reduced pressure of 0.3 g 1 m + 1119 on the permeate side. Place the membrane on the sMR surface with the active layer side facing the supply side.
Solution I was added and stirred at a constant temperature. The effective area of the film at this time is 1B, ffi ej. The water and organic compounds that permeated the membrane were condensed with liquid nitrogen and collected.

Kame-pbanol was added to the permeate as an internal standard.
The permeation amount and separation coefficient were determined by '1' OD-Gasque gastrograph. Note that the separation coefficient a of □ethanol with respect to water is defined as follows and is H,0.

YItO Luke H,0 However, in the above formula, X1tOH, Dimethylsilxane 11 fat (Shin-Etsu Chemical %IKf4!
1-T8) was coated on a Teflon plate to a thickness of 64 μm and left at room temperature for 8 days to obtain a polydimethylsiloxane film. The thus obtained liquid was placed in a pervaporator cell (effective area IIs, jIcI11). Add io Tol% ethanol aqueous solution 100-o into the cell.
A solution of g moles of sodium dihydrogen phosphate is added. In a constant temperature bath for about 30 minutes! Use a vacuum pump to suck the FFF$Q' side to approximately 0-381111H9 and l'! ! , vL was performed.

Transmission rate at that time (unit -・′；゛...y)・銚”
, θ The separation coefficient a of ethanol to water was 1\11 in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that the metal salt was -IIPO and the amount added was 0.1 mol. The permeation rate and separation coefficient were as shown in Table 1.

The membrane obtained by synthesizing the cowhide is pervaporation device cell ash 11.
(effective area 15.g C1l) and g- in the cell.

Add Vo1 ethanol aqueous solution 100-%40@0”
)X Leave in a constant temperature bath for 30 minutes. Next, the volume of the mixed liquid was suctioned to about 0.3-89% using a vacuum pump and separated. The results obtained are shown in Table 1.

Comparative example 2~? Example 1 about halides of sodium and potassium
The results were shown in Table 1.

Comparative Example 8,9 Vinegar f1 with 1 sodium and 1 potassium! The test was carried out in the same manner as in Example 1 for salt, and the results are shown in Table 1.
Space Gas 70 prepared by preparing a mixed liquid of potassium chloride, potassium bromide, sodium chloride, and ethanol aqueous solution
The water 1 ethanol activity (person (n@O) sum (mt
on) ) was measured. Its activity ratio c(IlltOH
) / M (Hso) ) (This shows the degree of movement of ethanol compared to 11 in water) 1: and “:
Example 1. IA/Comparative example 1~? ←Separation staff 1r'+
\111[, the relationship with chu gH is shown in Figure 1. For the halide of sodium 1potassium, there is a linear relationship between the activity ratio and the separation coefficient.
(to phosphoric acid) Sodium hydrogen deviates from this relationship.

This means that phosphates in the ethanol aqueous solution have a different ethanol selective permeability effect than halides.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the activity ratio of water to ethanol and the separation coefficient.

Claims (1)

[Claims] (1) A liquid mixture consisting of water and a water-soluble organic component! )-i-
(2) The separation method according to claim 1, wherein the metal is selected from the group consisting of lithium monosodium monopotassium, rubidium, and cesium. (8) Phosphorus compounds and derivatives thereof is phosphoric acid, i shoulder 7P
F'nic acid, phosphonic acid 1 phosphonite W11 phow++
'+r= ,