JPS607907A - Manufacture of dynamic membrane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dynamic membrane suitable for ultrafiltration applications.
#It is related to the manufacturing method. Specifically, the present invention relates to a method for producing a dynamic membrane made of a mixture of alumina sol and colloidal silica.

Conventionally, dynamic membranes using alumina sol are well known, and their ultrafiltration performance is, for example, in the case of filtration of a t% gelatin aqueous solution equivalent to type J engineering 81I, at a pressure of 20 k.
g,/crlG- A dynamic membrane made of silica in the form of a flow port along the membrane surface is also well known, and its ultrafiltration performance has been shown to be as low as 7 in the solute exclusion rate under the same conditions as above.
It was about ~9g. That is, according to the alumina sol dynamic membrane, 3 to 10% of the solute is lost along with the permeated water, and when the colloidal silica dynamic membrane is used, 2 to 3% of the solute is lost along with the total permeated water. It turns out.

Therefore, if the solute rejection rate that reaches the θ coefficient can be further improved by /point, it will be possible to reduce the amount of solute loss by a considerable percentage, and if the solute component is expensive, this effect will be extremely high. Thick.

Furthermore, the dynamic membrane of colloidal silica has the disadvantage that part of the membrane peels off during operations such as washing with water in the concentration process and the like.

In view of these circumstances, the present inventors have carried out intensive research and have found that by combining alumina sol and colloidal silica, the membrane has a higher solute removal performance than any of these individual materials. discovered that a dynamic membrane with excellent membrane stability could be produced by reflux treatment of an acid aqueous solution, and arrived at the present invention.

NIJ, the gist of the present invention is to form a membrane on a porous support by refluxing an aqueous solution of a mixture of alumina sol and colloidal silica under pressure, and then refluxing the mixture under pressure to a pH of 3, J.
The present invention relates to a method for producing a dynamic membrane in which an acid aqueous solution is refluxed.

The present invention will be explained in detail below.

Porous supports used in the present invention include various known ones, such as ceramics, sintered metal powder, sintered glass powder, inorganic porous supports such as carbon materials, cellulose acetate, polyvinyl chloride, and polymethacrylate. Examples include organic porous supports such as various synthetic resins such as lonitrile, polyamide, and fluorinated resin.

The pore size of the surface pores of the porous support varies depending on the material, but is usually 0. θ/~-μ, preferably 0. θ left ~ 0
．． −μ is better.

The thickness of the porous support may vary depending on the purpose of use of the dynamic membrane, as long as it has sufficient mechanical strength.

As for alumina sol, the particle size is θ x mμ~
<10θχ gθmμ, preferably loo×/θmμ ~ 3
Particles having a feather-like shape of 00×30 mμ are used, using an organic acid such as acetic acid, hydrochloric acid, or an inorganic acid as a stabilizer.

As colloidal silica, particle size s - so mμ,
ftT-IJ or 10-;1. Particles of Omμ granular shape are used. In addition, an aqueous solution of colloidal silica that is either acidic or alkaline stabilized can be used, but acidic and stabilized aqueous solutions are preferred.

In the present invention, the mixing ratio of colloidal silica and alumina sol is silica solid content/f shine, alumina solid content o
, o o o s~'0. ! ;g, preferably 0.00
/~0. /2 is good. If the amount of alumina is greater than this range, the stability of the dynamic film will decrease and the peeling will be reduced.
It is not desirable because it becomes dark.

The concentration of the mixed aqueous solution is 0.03~/, based on the solid content of silica.
0? /l, preferably θ, /~0. ! ;? /l is good.

The amount of powder in the mixed aqueous solution may be about 20 to 7 SOt per 7 rL' of the surface of the porous support.

The method described above can be used to produce a dynamic membrane according to the method of the present invention. In this method, 1. A mixed aqueous solution of alumina sol and colloidal silica is poured onto a tin porous support. Reflux is usually 2 to 3 k k under pressure.
g/crflG, good size mechanism 5 ~ λg kl, /c
yft G , the flow velocity still along the support surface (hereinafter simply referred to as flow velocity) 0. /~/Om/sec, preferably Ol, 2~,2 m/Bec. The temperature may be room temperature, and the reflux time may be 5 to 30 minutes, although it varies depending on the conditions.

Next, the acid aqueous solution of pH/~, :t, s fE, pT (/, 3-U, S) is refluxed under pressure. An aqueous solution is used.The reflux time varies depending on the species and species conditions, but may be 9 to 30 minutes.

This treatment promotes agglomeration of silica particles and forms a strong dynamic film.

Thereafter, the pressure is returned to normal and the inside of the flow path is washed with water, completing the formation of the dynamic membrane.

In the present invention, it is preferable to form a membrane from a mixed aqueous solution of alumina sol and colloidal silica, reflux the acid aqueous solution under pressure, and then reflux the heated water under pressure. In this case, heated water is refluxed under pressure and then returned to normal pressure to wash the inside of the channel with water to form a dynamic membrane. The heated water is usually 1I0~/θo'6, preferably 0~
100C is used. The reflux time varies depending on the conditions of each area, but may be from /S to qo minutes. This treatment further strengthens the bonds between the silica particles and also entangles them with the alumina particles, making it possible to form a strong dynamic membrane with a high solute exclusion rate.

It goes without saying that during the production of the dynamic membrane, the piece 1'll of the porous support through which the permeated water is discharged is always maintained at normal pressure.

The present invention will be further explained in detail below with reference to Examples and Comparative Examples, but the present invention is not limited by the following examples unless it goes beyond the gist of the present invention.

Example/ Particle size is λOθX20mμ~? θθ×30mH
z alumina sol and particle size 10-. 20 mμ of colloidal silica was dissolved and mixed in 301 of water. The concentration of colloidal silica is 0, . 2? /l, and the mixing ratio with alumina sol is 72 silica solids, alumina solids θ, θ0/? And so.

This aqueous solution was placed on a porous ceramic support (surface pore diameter: approximately 0./μ) of o, qq-IH,' under a pressure of 20 ky.
/crIG, flow rate 0. A m/sec, temperature, 2
The mixture was refluxed for 1.20 minutes under OC conditions to form a membrane.

Then the pH under a pressure of 20 ky/7 G,
2,:1, A 20C aqueous sulfuric acid solution was refluxed for 20 minutes.

Thereafter, the pressure was returned to normal and the inside of the channel was washed with water to form a dynamic membrane.

Using the dynamic membrane thus produced, a pressure of 20 k! , /cnrG 1 flow rate Q , 4 nL /
Under the condition of 59C1 temperature 60C, 3- equivalent to J Engineering S4'M
The aqueous solution of Tigelatin was filtered and the results are shown in Ibara-/7.

Examples 2 to 1 The mixing ratio of alumina sol and colloidal silica was calculated based on the silica solid content/V and the alumina solid content. The results are shown in Table 1.

Table - / Comparative Example 1 On a 0.77y1' ceramic porous support (surface pore size: approximately 0.7μ), colloidal silica with a particle size of /O~2Q mB was added as a solid content, and 62 was added to 30t of water. Dissolved aqueous solution at pressure 20 kg/Cnt G, flow rate 0.1
．． The mixture was refluxed for 20 minutes at a speed of m/sec and a temperature of 20C. When the pressure was then returned to normal and the inside of the flow path was washed with water, cloudiness was observed in the flowing water at the initial stage of washing, and a considerable portion of the silica had peeled off, making it impossible to conduct a filtration test.

Comparative Example 0.77 m2 ceramic porous support (surface pore diameter;
(approximately 0.7μ), and the particle size θOx20mμ~3
An aqueous solution of alumina sol of θOXJθmμ as a solid content and 2f dissolved in water 301 was heated at a pressure of 20 kg 1 crlG,
The mixture was refluxed for 20 minutes at a flow rate of 0.6 m/eec and a temperature of ao'6. Next, the pressure was returned to normal and the inside of the channel was washed with water to form a dynamic membrane.

Using the dynamic membrane thus produced, an aqueous solution of s-group gelatin was filtered under the same conditions as in Example 1, and the solute exclusion rate was 9AJ.

Sender: Mitsubishi Chemical Industries, Ltd. Mitsubishi Kasei Techno Engineers Co., Ltd. Representative Patent Attorney Hase - Others/names

Claims (2)

[Claims] (1) Form a membrane by refluxing a mixed aqueous solution of alumina sol and colloidal silica under pressure on a porous support;
Furthermore, the pH remains under pressure at 3! ; A method for producing a dynamic membrane characterized by refluxing the following acid aqueous solution. (2) The production method according to claim 1, characterized in that after the acid aqueous solution is refluxed under pressure, the kneaded and heated water under pressure is further refluxed.