JPS58183903A - Method for controlling permeation speed of water and organic liquid through regenerated cellulose membrane - Google Patents

Abstract

PURPOSE:To control the membrane permeation speed of water and an org. solvent, in separating a water-org. solvent mixed system, by subjecting the water- org. solvent mixed system to ultrafiltration by using a regenerated cellulose membrane preliminarily subjected to swelling treatment. CONSTITUTION:A regenerated cellulose membrane obtained by a cuprammonium method is dried at 105 deg.C for 2hr. At first, an aqueous ethanol solution ( I ) is poured in the upper part of the membrane to swell the same while permeated therethrough, and after the aqueous ethanol solution is removed, an aqueous ethanol solution (II) with ethanol content higher than that of the solution ( I ) is poured in the upper part of the membrane to be passed therethrough under reduced pressure. When the concn. of the aqueous ethanol solution ( I ) is lower than 70%, the permeation speed of the aqueous ethanol solution (II) is increased. When the concn. of the aqueous ethanol solution ( I ) is 90% or less and the concn. of the aqueous solution (II) is 30% or more higher than that of the aqueous solution ( I ), the increment of the permeation speed is especially remarkable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a regenerated cellulose membrane to remove a hydrophilic organic solvent and water from a homogeneous aqueous solution containing at least one kind of aqueous media. This invention relates to a method for controlling the permeation rate of an aqueous solution. More specifically, when removing a hydrophilic organic solvent from a homogeneous aqueous solution containing at least one type of organic solvent using regenerated cellulose mitt, a hydrophilic organic solvent containing a water content higher than the water content of the homogeneous aqueous solution is removed. The present invention relates to a method for controlling the permeation rate in a regenerated cellulose membrane, in which the regenerated cellulose membrane is swollen in advance with a solvent, and then a target hydrophilic organic solvent and water are permeated therethrough.

In general, 1 regenerated cellulose membrane swells very well with water due to its hydrophilic nature, but it can also be swelled with water such as aliphatic swelling hydrogen, aromatic hydrocarbons, alcohols such as methanol, ethanol, gropanol, butanol, and acetone. Some ketones, such as ′, hardly swell. Therefore, the rate at which these organic solvent molecules permeate through a non-porous regenerated lulose membrane with a pore size of 100X or less is very slow. Therefore, in the past, no attempts have been made to utilize regenerated cellulose membranes for the separation of organic solvents, and the main use of KII aqueous membranes has been unsuccessful for the separation of organic solvents. The non-porous cellulose membrane with a pore diameter of 100X or less means that the pores cannot be observed with a scanning electron microscope, etc., and the average pore diameter determined by other feeding methods is 1 oa.
It means a regenerated cellulose membrane that is X or less.

However, the manufacturing method for regenerated cellulose membranes has been thoroughly researched, and the products have good stability and can be easily processed into any shape, including flat membranes and hollow membranes. Furthermore, since it is made from cellulose, which is completely harmless as a component, its range of use is increasingly expanding to include hemodialysis, food, and pharmaceutical products.

The inventors of the present invention have conducted extensive studies aimed at utilizing regenerated cellulose membranes for the separation of water-organic solvent mixture systems while taking advantage of various advantages of regenerated cellulose membranes. The present inventors have discovered that if a regenerated cellulose membrane is previously subjected to a swelling treatment, the permeation rate of a water-organic hot medium mixture can be dramatically increased, and the present invention has been completed.

That is, in the present invention, when removing a hydrophilic organic solvent and water from a homogeneous aqueous solution containing at least one organic solvent, the FA method outside the regenerated cellulose molecular chain is applied to remove the homogeneous aqueous solution. This is a method for controlling the permeation rate of water and a solvent in a regenerated cellulose membrane, which is characterized by subjecting the regenerated cellulose membrane to a swelling treatment in advance with a hydrophilic organic solvent containing a water content higher than the water content. Here, the ultrafiltration method refers to a method of permeating a liquid through a membrane using a pressure difference capable of discharging the load on the membrane as a driving force.

The present invention will be explained in detail below.

When a non-porous regenerated cellulose membrane is dried at 105°C for 2 hours or more to an absolutely dry state, the permeation coefficient of hydrophilic organic solvents such as methanol, ethanol, and acetone into the membrane is 10'''l (d /cum, +uag) below, this OI
It is almost impossible to utilize I as a membrane separation technology industrially. This is because the regenerated cellulose membrane rarely swells when exposed to these organic solvents, and is thought to be due to the inability of solvent molecules to diffuse into the cellulose molecular chains10. be done. The impermeability of a non-porous regenerated cellulose membrane to organic solvents disappears as the pore size of the membrane increases, but when the average pore size is 1001 or less, it is uniformly impermeable to organic solvents. In other words, when the average pore size exceeds 100X (approximately zoaX in the presence of water), it becomes difficult to selectively permeate water and a hydrophilic organic solvent through the membrane under pressure or reduced pressure.

For methanol, ethanol, acetone, membrane area 1
When the aSJ6 ring of the present invention is not applied to the regenerated cellulose membrane obtained by the five methods of cuproammonitoring at 0 m, the membrane is heated under reduced pressure (1 m
Hg) under (ΔP-759ml1g) I
The permeation rate was less than G''at/hr.

However, by the process of the present invention, it is also possible to increase the transmission rate by more than twice ttlOQ.

By mixing water with an organic solvent and examining the permeation rate of the mixture under reduced pressure or pressurization using a mixture of IL) and organic solvent at various ratios, it is found that the mixing ratio of water is It was found that as K increases, the permeation rate of the mixed liquid increases, and the case of water 712% exhibits the highest permeation rate. this is,
It is believed that 6-cellulose is JI#L due to the diffusion of water molecules into the cellulose molecular chains, and its swelling f increases with the amount of water contained in the solution.

In this way, once a mixture of water and an organic solvent with a certain composition t
I) or by immersing the membrane in such a mixture, the membrane is made to contain a certain amount of moisture.
After c11M, a mixed solution (I) of water and organic solvent containing the same type of organic solvent and having a lower moisture content than the mixed solution (I) of water and organic solvent used for swelling was heated under pressure. Alternatively, when the mixture liquid (2) of water and an organic solvent is permeated through the membrane under reduced pressure, immediately after the swelling treatment is performed, the mixture of water and an organic solvent (2) is permeated through the regenerated cellulose membrane under pressure or under reduced pressure. The permeation rate increases dramatically.

In this case, the greater the difference in water content between the mixed liquid (I) and the mixed liquid (2), the greater the increase in the permeation rate to. Further, it is preferable that the moisture content of the liquid mixture (I) used for the initial swelling is 5% or more; if it is 5% or less, no increase in the permeation rate is observed before and after the swelling treatment. In addition, treatment at a moisture content of 1009 G causes moisture F to flow out to the FiFl side, which is not desirable, and operability is usually better when the moisture content is 98 or less.

Note that the swelling treatment is usually carried out at a temperature in the range of 20 to 100°C, but the treatment time can be shortened if the treatment temperature is higher. The processing time required for rounding to improve reproducibility is one hour or more.

Although it is not clear in detail why the permeation rate of the mixture of water and organic solvent through the regenerated cellulose membrane is uniquely determined by the swelling treatment in 1., the present inventors have determined the following. That's what I'm thinking. That is, 1) the regenerated cell p-su membrane swells with water, and the swelling increases as the water content in the mixed solution of water and organic solvent increases; 2)
Once diffused and adsorbed into the cellulose molecular chains, water molecules do not desorb from the cellulose molecules even if the composition of the solution passing through the membrane changes. 3) In the nine-regenerated cellulose membrane swollen with water,
Hydrophilic components are 1+ #1 with a large amount of adsorbed water molecules, etc.
We believe this is due to the fact that the organic solvent is easily permeable.

The regenerated cellulose membrane referred to here is a membrane made of cellulose that exhibits the Rulose ■ type or [-2 type crystal type and has an average polymerization longitudinal DP of 100 or more, and the hydrophilic organic solvent is , an organic solvent that exhibits overall liquid-liquid miscibility with water, and whose solubility in water at 20° C. is usually 5avI (volume ratio) or higher. For example, methanol, ethanol, impropatol, glopanol,
Examples include sec-butanol, isobutanol, acetone, and the like.

As mentioned above, when a mixed liquid of an aqueous organic solvent and water is passed through the regenerated cellulose membrane tIl, the water content is higher than that of the mixed liquid of water and an organic solvent to be permeated, and the organic solvent to be separated and removed. (I) A mixture of water and an organic solvent containing
When the regenerated cellulose membrane 4r11 is swollen and the target mixture (2) of water and an organic solvent is passed through the bale, the mixture of water and organic solvent (2) is made to swell even when the swelling treatment is not performed. This regeneration of the liquid can significantly increase the permeation rate through the reulose membrane, and the swelling treatment KJ!
1 Mixed solution of water and organic solvent (I) 0 By adjusting the moisture content, the permeation rate of water, organic solvent, and OS mixture (1) can be uniquely determined.

As the belly used in the present invention, dragon lurose ■ type crystal l1
If it is a film made of regenerated cellulose with a T-resistance and an average degree of polymerization DP of 100 or more, the effect can be fully expected, but from the viewpoint of film strength, reproducibility, and the ability to express the effects of the present invention, the cuprammonium method is not suitable. A membrane is most desirable, and the shape of the membrane may be planar, tubular, spiral, or hollow fiber. Furthermore, among the wood-philic bridged solvents, methanol, ethanol, and acetone are particularly effective in the present invention. The permeation rate of isopropanol, tetrapanol, sec-butanol, isobutanol, etc. is also increased by the 11 wet treatment of the present invention, but not for the former three, such as t1.

The effects of the present invention are listed below.

1) The permeation rate of a hydrophilic organic solvent or a mixture of the organic solvent and water through a non-porous regenerated cellulose membrane can be freely controlled.

2) In a mixed system composed of three or more components of two or more types of organic solvents and water, it is possible to selectively separate the hydrophilic organic solvent and water.

3) The filtration rate can be increased in ultra-precise filtration of pharmaceutical ethanol aqueous solutions.

For the measurement of pore diameters of 200λ or less, refer to Polymer Science and Technology, Vol. 15.

ULTRA FILTRAGE 1 MEMPLENS AND.
App Cage (Polymer 5science)
andTechnology, Vol. 131,
Ultrafiltration Membranes
and Application (Plenum P
ress )) K, K described on page 017s
amide, 8. According to Manabe's method, dry l! The value twice the average pore diameter in water was defined as the average pore diameter in water.

The invention will be specifically explained below using examples of the present invention, but #
The membrane permeability of medium I was determined using a vapor permeation method (Perv) using a 4711φ pressure filter holder manufactured by Millibore.
It was evaluated by the aporation method). That is, a mixed solution of water and an organic solvent was placed on top of the membrane, and the permeation rate of the mixed solution passing through the membrane was measured under reduced pressure.

Example 1 Using ethanol as a solvent, a regenerated cellulose membrane (
Thickness: 17K, average pore diameter: 72X, -DP=450) 10
After drying at 5℃ for 2 hours, this experimental device (membrane area?
c11).

First, an aqueous ethanol solution (Il 2 ) is added to the top of the membrane to swell the membrane, and the solution is allowed to permeate through the membrane.

Next, the ethanol aqueous solution (I) is removed, and the ethanol aqueous solution (I) is injected onto the membrane upper part of the ethanol aqueous solution 01, which has a higher ethanol content, and is allowed to permeate through the membrane under reduced pressure. Ethanol aqueous solution (I)
, [1) The composition and the permeation rate at that time are shown in Table 1.

Table 1 Change in permeation rate due to swelling treatment 2) Concentration -
is % by weight From the results above, it can be seen that when a 70% ethanol aqueous solution is permeated, when the ethanol concentration of the ethanol aqueous solution (I) is lower than 70-, the permeation of 1 ethanol aqueous solution 0 (in this case, 70%) is Speed is increasing.

%, the reason why the permeation rate increases significantly is because of the concentration of the ethanol aqueous solution (I) used for the swelling treatment of the regenerated cellulose membrane!
〇- or less, and the concentration of the permeated aqueous ethanol solution 0 is higher than the concentration of the aqueous ethanol solution (I), and 30
-This is the case above. When passing 100% ethanol gold, if you first swell it with water and then allow 100% ethanol to pass through it, the permeation rate will be about 180 times that of the case without swelling treatment. Regarding the three-component system of water/ethanol/methylene chloride as the permeation solvent, water/ethanol permeation rates similar to those shown in Table 1 were obtained.

Example 2 Using the same experimental apparatus as in Example 1, the permeation rate of an acetone aqueous solution was measured under reduced pressure. The membrane used was a regenerated cellulose membrane (thickness 20 μm, average pore size s 6X, op = 29 o) obtained by a known viscose method. This film t
When a 70% thiacetone aqueous solution is permeated after drying at 105°C for 2 hours, the flow rate is 4.5 wl/h without swelling treatment.
However, if you pass through the 50% thiacetone aqueous solution once and then pass through the 00% acetone aqueous solution, the result will be 10. Od
/hr K permeation rate increased. Further swelling treatment 2
- When the acetone aqueous solution is passed through the 20-acetone aqueous solution, the permeation rate & is 14.5 d/h.
It increased to r.

Similarly, when transmitting 100 thiacetone, the permeation rate was 0 and 0 t sd/hr without swelling treatment, but after swelling treatment with 50 thiacetone aqueous solution and 2 liters of acetone aqueous solution, the permeation rate was 17.0 sd/hr, respectively. Oml/hr.

This dramatically increased to 25.6 d/hr.

Example 3 Using the same experimental equipment as in Example 1, 2. Using a five-component mixture of acetone/toluene/water under the pressure of Oky/csf, the water and acetone phases were selectively permeated.

The water and acetone phase is located at the bottom of the toluene/acetone phase.

The cuproammonium regenerated cellulose membrane employed in Example 1, which was swollen with an aqueous solution of 2 g of acetone, was swollen under reduced pressure.
The water/acetone phase in contact with the membrane was filtered at a permeation rate of zoo/hr, but the toluene/acetone phase did not pass through at all.

Claims (1)

[Scope of Claims] 1. In removing a hydrophilic organic solvent and water from a homogeneous aqueous solution containing at least one organic solvent, an ultrap-optimal method using a double-liquid lurose expansion is applied to remove the homogeneous aqueous solution. 1. A method for controlling the permeation rate of water and an organic solvent in a regenerated cellulose membrane, the method comprising preliminarily treating the regenerated cellulose membrane with a hydrophilic organic solvent containing a moisture content of at least . 2. A method for controlling the permeation rate of water and organic solvents in a regenerated cellulose membrane according to claim 1, which uses a membrane obtained by the cuproammonia method as the regenerated cellulose membrane. 3. The method for controlling the permeation rate of water and organic solvents in a regenerated cellulose membrane according to claim 2, wherein the average pore diameter of the regenerated cellulose membrane obtained by the cuproammonia method is 200λ or less. 4. A method for controlling the permeation rate of water and an organic solvent in a regenerated cellulose system according to claim 1, wherein the hydrophilic organic solvent is methanol, ethanol or acetone. 5. The method for controlling the permeation rate of water and an organic solvent in a regenerated cellulose membrane according to claim 1, wherein the water content of the aqueous solution of the hydrophilic organic solvent used to swell the regenerated cellulose membrane is 10g1 or more.