JPS6061005A - Separating process of substance - Google Patents

Abstract

PURPOSE:To separate particular molecules or ions from >=2 kinds of molecules or ions contained as mixture in aq. soln. with high efficiency, quickly and with a simple procedure by allowing to perform separation and transportation separately by each separate mechanism. CONSTITUTION:Precision for separation is improved by imparting to a collector which is soluble in a solvent immiscible with water a high selectivity for a molecule or ion. Further, a high molecular porous film having >=0.01mum average pore size is used to perform microscopic phase separation into two phases. Preferred average pore size of the high molecular porous film is 0.1-10mum, and any material is usable so far as it can be formed to film. Moreover, the difference of solubility parameter between materials for each film constituting two kinds of high molecular porous film is preferred to be >=3(Cal/cm<2>)<0.5> in order to perform separation of an aq. phase and a solvent phase using 2 kinds of high molecular porous film having different solubility parameter with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for selectively separating substances dissolved in an aqueous solution. A substance that mixes a solvent that is immiscible with water and the water bath liquid to cause a phase separation state, and then separates the solution in a phase separation state using a porous polymer membrane having an average pore diameter of o, oi μm or more. Regarding the separation method.

Conventional technology L-distillation method, adsorption method,
Membrane separation methods, extraction methods, etc. are known, but these methods need to be used depending on the nature and amount of the substance to be separated, and the purpose of separation. However, at present, there is no known separation method that simultaneously satisfies all of the basic requirements such as high separation speed and separation power, low energy consumption and equipment cost.

It is superior to other separation methods in terms of the wide range of targets to be separated by distillation normal separation, as well as separation speed and separation accuracy, and is widely used industrially, but it is inferior to other separation methods in terms of energy cost and equipment cost. It cannot necessarily be said that it is superior.

In the conventional solvent extraction method, the two phase-separated phases must be allowed to stand still to separate the upper and lower layers, and a large-capacity standing tank is indispensable when processing a solution of fata. Therefore, there is a problem that a large amount of solvent remains during the process, and if the solvent and scavenger are expensive, the separation cost increases. In addition, in order to perform efficient separation, a complicated structure of separation equipment and a long process time are required, and especially when the density difference between the two phases is small, it is not possible to separate them into small particles by standing still. This method is not suitable.

The average pore size of reverse osmosis, ultrafiltration, etc. is 100A or less (
Membrane separation methods using polymer membranes (0.01 μm or less) are said to be superior to distillation methods in terms of energy costs and equipment costs, but the separation speed is low and the selectivity is not satisfactory. It's not a kimono.

On the other hand, in conventional membrane separation methods using membranes with an average pore size of 0.01 μm or more, it has generally been impossible to separate dissolved low molecules.

Purpose and Structure of the Invention The present inventors have developed a method for efficiently and quickly separating molecules or ions from two or more types of molecules or ions mixed in water rG with a short time and simple operation. As a result of extensive efforts to achieve this goal, the present inventors have discovered that the separation speed can be significantly increased by dividing separation and transportation into separate mechanisms, respectively, and have arrived at the present invention.

That is, in the present invention, a scavenger Z having the property of specifically capturing the substance Y to be separated is dissolved in a solvent X that is immiscible with water, and the solvent X in which the scavenger Z is dissolved is mixed with the substance BY. It is mixed into the dissolved water bath liquid to cause a phase separation state of a phase mainly composed of water (hereinafter abbreviated as aqueous phase) and a phase mainly composed of solvent X (hereinafter abbreviated as solvent phase). After the substance Y in the aqueous phase is selectively taken into the solvent phase by a liquid film formed at the interface between the solvent phase and the aqueous phase, the aqueous phase and the solvent phase are separated with an average pore diameter of 0. The porous polymer membrane having a diameter of 0.01 μm or more is used to separate the substances, and with this structure, it is possible to selectively separate the substance Y dissolved in the aqueous solution.

Description of Structure and Effects of the Invention The first feature of the present invention is to improve the separation accuracy by giving the scavenger 2, which dissolves in the solvent X which is immiscible with water, a high degree of selectivity for molecules and ions. It is. The solubility of solvent X in water is less than 10% by weight, preferably 0.1% by weight.
It is as follows.

The second feature of the present invention is that by using a large porous polymer membrane with an average pore size of 0.01 μm or more, two phases that have undergone chromophase separation can be separated.

Due to these two characteristics, the method of the present invention can achieve very high separation speed and high resolution.

When the average pore diameter of the porous polymer membrane is less than 0.01 μm, the separation rate decreases significantly, and if the pressure applied to the membrane is increased in an attempt to increase the separation rate, the separation performance decreases, and in some cases, after microphase separation. separation of the aqueous phase and solvent phase becomes impossible. Therefore, the average pore diameter of the porous polymer membrane is 0.
The thickness is preferably 1 μm to 10 μm, more preferably 0.2 μm.
It is μm to 1.0 μm.

The porous polymer membrane used in the present invention may be made of any material as long as it can be formed into a membrane. A single material may be used, or a plurality of materials with different solubility parameters may be blended to form a film forming material in order to adjust the affinity on the film surface. Examples of porous polymer membrane materials include:
Cellulose acetate (solubility parameter 12.03-13
．． 14 (Cal/c+4)'), regenerated cellulose (24
,08), nylon 6 (12,43), polysulfone (12,61), polyethylene (8,56), polypropylene (8,02), polyvinyl chloride (11,03),
Polymethyl methacrylate (9,93), polyacrylonitrile (14,39), polytetrafluoroethylene (6,2
), polychlorinated trifluoroethylene (7,2), polybutadiene (8,40), polyethyl methacrylate (9,
ω, polyvinyl alcohol (19,06), etc. However, in the case of a composite membrane in which the surface and interior of the porous membrane have different chemical compositions, the solubility parameter of the chemical compound forming the surface of the porous membrane is taken as the solubility parameter of the porous membrane. In addition, when a plurality of materials having different solubility parameters are blended, the sum of the products of their constituent overlapping fractions and solubility parameters is conveniently taken as the solubility parameter of the porous membrane.

When the aqueous phase and the solvent phase exist in a state of diachromatic phase separation,
If two types of porous membranes with different solubility parameters are appropriately selected, only the aqueous phase can pass through the porous membrane with a high solubility parameter, and only the solvent phase can pass through the porous membrane with a low solubility parameter. These permselective properties are developed due to the difference in interfacial tension between the macromolecular phase-separated phases and the porous polymer membrane. In order to efficiently separate the aqueous phase and the solvent phase using two types of porous polymer membranes with different solubility parameters, two types of porous polymer membranes tl-
The difference in solubility parameters of the constituent membrane materials is 3.
(Cal/cd) ″A or more is desirable, 10
It is a desirable combination if there is a difference of (Cal/, 4)"/z or more. Even if the difference in solubility parameters is less than 3, if the operating pressure is lowered and the pore size is made smaller, the two-phase Separation is possible, but the processing per unit time is 1
Less is.

The optimum average pore diameter and operating pressure of the porous membrane are determined as appropriate in consideration of separation efficiency. In order to increase the permeation rate, it is desirable to set the average pore diameter as large as possible. Furthermore, the membrane can be used in any form, such as a flat membrane, a hollow fiber, or a spiral, essentially without distinction.

If the substance to be separated is a metal ion, it is possible to determine the optimal combination of chelating agent and metal ion among various chelating agents as a scavenger based on ion selectivity and solubility in the solvent. Wear.

For example, in the case of separating υ copper from an aqueous solution containing copper ions, two types of salicradoxime derivatives, LIX65N or 8-hydroxyquinoline substituted product, can be used as the chelating agent. As the solvent in this case, an organic solvent that is immiscible with water, such as xylene, toluene, or cyclohexane, can be used.

In addition to chelating agents, di-2-ethylhexyl phosphoric acid, naphthenic acid, and versatic acid
It is possible to separate cobalt and nickel by dissolving organic acids such as in an organic solvent, and it is also possible to separate uranium by fermenting tributyl phosphate in an organic solvent.

In the present invention, it is desirable that the bath liquid in the microphase-separated state is in an agitated state, and it is better to simultaneously use two types of membranes with as large a difference in solubility parameters as possible to continuously separate them. Desirable when maintaining high efficiency.

EXAMPLES The present invention will be described in detail below, but it goes without saying that the technical scope of the present invention is not limited to these Examples. In the present invention, the average pore diameter 2ra is measured as follows.

Measuring method of average pore size 2RA> Pure water at 25°C was heated to a polycarbonate porous membrane with a pore size of 0.2 μm (manufactured by General Electric Co., trade name: nuc).
lepore) to prepare pure water free of fine particles. Using this pure water, a constant pressure difference △P (m
If we measure the filtration rate J (cm/5ec) per unit area of the sample porous membrane at
m) can be calculated using the following formula.

Here, ηW is the viscosity of pure water and is usually 1 centipoise.

d is the thickness of the film (country) and is measured with a micrometer.

Examples 1-4 Cellulose linter (viscosity average molecule 1:2.4X10
) in a copper ammonia solution prepared by a known method.
After dissolving 2 parts at each concentration of 1%, add 15% acetone to the solution.
After stirring, the solution was cast with an applicator to a thickness of 250 μm onto a glass plate placed in an acetone vapor atmosphere at 30°C with a saturated vapor pressure of 80 cm. , and left in this atmosphere for 10 minutes. Next, it was immersed in a 20°C sulfuric acid water bath for 15 minutes, then washed with water, the moisture was absorbed with P paper, and the water was soaked in acetone at 20°C for 15 minutes.
The membrane was immersed for 1 minute to replace the moisture in the membrane with acetone, then sandwiched between sheets of P paper and air-dried at 30°C.
A cellulose porous membrane with a size of μm or more was prepared. This film thickness was approximately 40 μm.

On the other hand, a polypropylene porous membrane (average pore size -1.2X10'''4C#!) prepared by a known method was used as a polymeric porous membrane made of a material with a low solubility parameter such as regenerated cellulose.
, a film thickness of 1.5×10-”m, and a porosity of Pr-75%).

”/Cu80a + in 10M acetate buffer (pH 5,0)
15H20 was dissolved at various concentrations to prepare an aqueous solution (~) containing copper ions.On the other hand, the chelating agent LIX65N (
A solution (manufactured by Henkel Japan) was dissolved in toluene to a volume of 25 vol.

Two disk-shaped membranes with a diameter of 47111 as shown in Figure 1,
A regenerated cellulose porous membrane 1 is placed on one side of a container that can be mounted facing each other, and a polypropylene porous membrane 2 is placed on the other side.
, mix the solution (~ and solution (B) at a volume ratio of 1:1, inject it into the interior 8 of the container 0, and mix it with the stirrer 6 at υ150
rl) m. The solution in the interior 8 of the container O was in a state of microphase separation and was opaque.

The permeated liquid (C-1) that permeated through the regenerated cellulose porous membrane 1 and the permeated liquid (C-2) that permeated through the polypropylene porous membrane 2 were both in a uniform one-phase state.

Aqueous solution (~, copper ion concentration of permeate (e-1) is 830
The absorbance was calculated in nm. Aqueous solution (~ and permeate (C-1)
) are summarized in Table 1. As shown in Table 1, the copper ion concentration of the permeated WCC-1) that passed through the regenerated cellulose porous membrane 1 was reduced to about 172 b of solution N.

Example 5 Using the same equipment as in Examples 1 to 4, the volume ratio of solution (~ and solution 0) was 1:2. It was better.

Filtration was carried out under the same conditions as in the ft1l experiment except that stirring was not performed. As shown in Table 1, the concentration of permeated liquid C-1 hardly changed, and the permeation rate was also small.

Example J Examples 6 to 8 The permeate that passed through the polypropylene porous membrane 2 in Example 9'l12 was added to (C-2) with a sulfuric acid water bath solution (PI-11,0
) was added from a specified company and separated into permeate/l of regenerated cellulose porous membrane 1 [(1)-1) and permeate of polypropylene porous membrane 2 (D-2) using the same membrane separator as in Examples 1 to 5. .

As shown in Table 2, according to the present invention, copper ions can be concentrated in the permeate (L)-1).

anus

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an aspect of one representative example of a membrane separation apparatus used in the method of the present invention. 1...Regenerated cellulose porous membrane, 2...Tearless porous g, a, a'...Stainless steel mesh, 4.4'
...〇-Ring, 6... Stirrer, 7... Magnetic stirrer, 8... Inside the container.

Claims (1)

[Claims] 1. A solution in which a capture agent Z that specifically captures substance Y is dissolved in a solvent X that is immiscible with water is mixed with an aqueous solution in which substance Y is dissolved, and water is the main component. After causing a microphase separation state between a phase (aqueous phase) and a phase (solvent phase) containing the solvent X as a main component and selectively incorporating substance Y into the solvent phase,
A method for separating substances, which comprises separating an aqueous phase and a solvent phase using a porous polymer membrane having an average pore diameter of 0.01 μm or more. 2, the difference in solubility parameters is 3 (Ca 17ml
1) A method for separating substances according to claim 1), which uses two or more types of porous polymer membranes comprising two or more types of polymer substances. 3. Claim 1, in which the substance Y is a metal ion 1, and the capture agent 2 is a chelating agent that specifically captures metal ions
A method for separating the substance described in Section 1 or Section 2. 4. The method for separating substances according to claim 1, 2, or 3, wherein the porous membrane has an average pore diameter in the range of 0.02 μm to 10 μm.