JPS5814262B2 - Mukitsuion Kokanmaku Oyobi Sonoseizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion exchange membrane, more specifically to a novel ion exchange membrane comprising at least one oxoacid of iron, cobalt, nickel or manganese and asbestos fibers, and a method for producing the same. be.

Although conventional resin ion exchange membranes have excellent performance,
It cannot be said that the radiation resistance, heat resistance, oxidation resistance, etc. are still sufficient.

On the other hand, the applications of ion-exchange membranes are expanding with the trend of resource and energy conservation, and there is a demand for membranes with higher performance and ability to withstand harsher environments.

Inorganic ion exchangers have excellent radiation resistance, retain their exchangeability even under high temperatures, and are stable against strong oxidizing agents, but they are difficult to form into films, lack chemical resistance, and have their characteristics I couldn't take advantage of it.

As a result of research on inorganic ion exchange membranes, the present invention uses materials that can be obtained at low cost, has excellent radiation resistance, heat resistance, oxidation resistance, and chemical resistance, and also achieves the original purpose of achieving selectivity and high current flow. The present invention provides an extremely simple method for manufacturing ion exchange membranes that maintains efficiency.

The ion exchangers used are iron, cobalt, nickel or manganese oxoacids or mixtures thereof.

Oxoacids of iron, cobalt, nickel or manganese are
It is represented by the general formula XOm(OH)n or HnXOm+n (X is iron, cobalt, nickel or manganese, m and n are positive real numbers), and at low pH, it is an anion exchanger,
It is known that it is a cation exchanger at high pH.

In terms of chemical resistance, those that have been fired or hydrothermally treated are highly crystalline and chemically stable.

For example, iron oxoacids are not only stable against alkalis in water and salt solutions, but also stable against weak acids in an oxygen atmosphere.

Iron, cobalt, nickel or manganese oxoacids are obtained by alkali treatment of soluble iron, cobalt, nickel or manganese salts.

Asbestos fibers have a good affinity for soluble salt solutions of Group III or manganese. For example, when a soluble salt solution of iron is mixed with polymer fibers or carbon fibers and concentrated, the salt will be liberated at a saturation concentration. When mixed with wire fibers, it is not liberated even at a saturation concentration or higher.

Soluble salt solutions of iron, cobalt, nickel or manganese are acidic, and asbestos fibers are easily defibrated in acidic solutions.

Moreover, asbestos fiber has excellent oxidation resistance and chemical resistance, and is not expensive.

One of the features of the present invention is the utilization of the mutual properties of this asbestos fiber and a soluble salt solution of iron, cobalt, nickel, or manganese.

The method for manufacturing the ion exchange membrane of the present invention begins with iron, cobalt,
A solution consisting of at least one of soluble salts of nickel or manganese is applied to asbestos cloth, asbestos paper, or asbestos board, or asbestos fibers are dispersed in the solution and concentrated to form a film.

After drying these, by treating them with alkali, iron,
An ion exchange membrane consisting of cobalt, nickel or manganese oxoacid and asbestos fibers is obtained.

When coating or impregnating asbestos cloth, asbestos paper, or asbestos board, the solution concentration of soluble salts of iron, cobalt, nickel, or manganese can be arbitrarily selected from a very low concentration to a saturated concentration. In the sense of shortening the next drying time, 10
% or more is preferable.

Since there is a possibility that the film becomes porous after drying, it can be improved by repeating the coating-drying operation.

Furthermore, using asbestos cloth, asbestos paper, or asbestos board as a diaphragm, using a soluble salt solution of iron, cobalt, nickel, or manganese as the anolyte and using an alkaline solution as the catholyte, asbestos cloth, asbestos paper, or asbestos board was electrolyzed. It is also possible to impregnate and apply a Group Ⅰ element or manganese oxoacid.

Next, when asbestos fibers are dispersed in a soluble salt solution of iron, cobalt, nickel, or manganese, the weight ratio of iron, cobalt, nickel, or manganese to asbestos fibers is determined in units of iron, cobalt, nickel, or manganese. Manganese/asbestos fiber = 5/95 to 75/25.

If the concentration of iron, cobalt, nickel or manganese is too high, the film strength will be reduced and it will be difficult to form the film, and if the fiber concentration is too high, a large amount of solvent will be used to uniformly disperse the fibers, resulting in poor quality. The membrane that has risen also becomes porous.

Therefore, the weight ratio is preferably 10/90 to 60/40.

Methods such as extrusion molding, compression molding, and casting can also be used to mold this mixture into a film.

In both the method of applying or impregnating a solution onto asbestos cloth, asbestos paper, or asbestos board, and the method of mixing the solution and asbestos fibers to form a film, drying is the next step.

Drying is carried out between room temperature and the boiling point of the solvent.

For example, when water is used as a solvent, 60°C to 90°C
Drying for 30 minutes to several hours is sufficient.

After drying, the membrane is immersed in an alkaline solution to precipitate iron, cobalt, nickel, or manganese oxoacid.

The concentration of alkali is not particularly limited, but is preferably 5% or more.

Although the reaction can occur even if the alkali treatment temperature is low, soluble oxoacid salts may be produced at low temperatures, so a temperature of 40° C. or higher is preferable for chemical resistance.

As iron, cobalt, and nickel, iron, cobalt, nickel, and others can be considered, but ordinary iron,
Cobalt and nickel are used.

Soluble salts of iron, cobalt, nickel or manganese include chlorides, sulfates, nitrates and the like.

Furthermore, the solvent is not limited to water; alcohols and Kents can also be used depending on the properties of the salt.

The alkalis used to precipitate oxoacid are:
These include caustic soda, caustic potash, and ammonia.

Examples of asbestos fibers include chrysotile, amosite, and crondrite.

The inorganic ion exchange membrane thus obtained can also be used together with other fibers or porous membranes for reinforcement.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Asbestos paper for electrolytic diaphragms manufactured by Asahi Asbestos Industries ■ ASK No. 2100
A 30% aqueous ferric chloride solution was applied to a thickness of about 0.7 mm using a plastic spatula.

The surface of the asbestos swelled with the aqueous solution, and eventually the inside was impregnated with the liquid.

It was dried in a dryer at 85° C. for about 1 hour, and a 30% aqueous ferric chloride solution was applied and dried.

This operation was repeated 5 times.

Thereafter, this dried film was immersed in a 20% caustic soda solution at 60° C. for about a day and night, washed with water, and stored in water.

The ion exchange membrane thus obtained was stable in an alkaline solution and also in an oxidizing atmosphere at pH 3.

After leaving it in 0.5N saline for about 2 hours, the electrical resistance was measured.

It was about 9 Ω-cm 2 at a temperature of 23° C. and an AC IKHz.

Example 2 4T-04 asbestos fiber manufactured by Johns Manville was dispersed in an aqueous ferric chloride solution.

The weight ratio of asbestos fiber and ferric salt is Fe/asbestos fiber -2
At o/s O, water was added in an appropriate amount to facilitate the disintegration of asbestos.

Thoroughly knead and concentrate in a dryer at 80°C.

A clay-like composition is obtained by kneading occasionally to prevent the surface from becoming too dry.

This composition was pressed to a thickness of approximately 1 mr/L.

After drying in a drier, it was treated with alkali at 80°C using 30% caustic soda.

This ion exchange membrane is stable even in an alkaline solution and in an oxidizing atmosphere of pH 3.

Similar to Example 1, when measuring the electrical resistance, the temperature was 23°C.
, about 12 Ω-cm 2 under AC IKHz.

Next, asbestos was further reduced and Fe/asbestos fiber was 75/25.
It was found that a membrane prepared in the same manner as 2000-2000-2000 was susceptible to cracking and could not be used alone, but could be used, for example, if it was supported on a porous substrate.

Further, a material having a Fe/asbestos fiber ratio of 5/95 tends to become porous, which is not desirable.

Example 3 Example 20 Asbestos fibers were dispersed in a 30% aqueous solution of nickel sulfate.

The weight ratio of asbestos fibers and nickel sulfate is Ni/asbestos fiber=30/70 using Ni units.

Concentrate in a dryer in the same manner as in Example 2 to obtain a clay-like composition,
Then, a film was formed using a roll press, and after drying, the same alkali treatment as in Example 1 was performed.

After that, it was washed with water and stored. When the electrical resistance was measured in the same manner as in Example 1, it was approximately 14 Ω-cm at a temperature of 23°C and an AC IKHz.
It was 2.

Example 4 The asbestos fibers of Example 2 were dispersed in a 20% cobalt chloride aqueous solution.

The weight ratio of asbestos fibers to cobalt chloride is Co/asbestos fibers 30/70 using CO units.

Concentrate in a dryer in the same manner as in Example 2 to obtain a clay-like composition,
Then, a film was formed using a roll press, and after drying, the same alkali treatment as in Example 1, washing with water, and storage were performed.

When the electrical resistance was measured in the same manner as in Example 1, the temperature was 23°C,
It was approximately 17 Ω 1 cm2 under 1 KHz AC.

Example 5 Example 20 Asbestos fibers were dispersed in a 20% manganese acetate aqueous solution.

The weight ratio of asbestos fibers to manganese acetate is Mn/asbestos fibers 30/70 using Mn units.

Concentrate in a dryer in the same manner as in Example 2 to obtain a clay-like composition,
Then, a film was formed using a roll press, and after drying, the same alkali treatment as in Example 1, washing with water, and storage were performed.

When the electrical resistance was measured in the same manner as in Example 1, the temperature was 23°C,
It was about 13 Ω-cm under AC IKHz.

Example 6 Fe/asbestos fiber-2 produced in the same manner as Example 2
Salt water was electrolyzed using a 0/80 ion exchange membrane with a thickness of 1.2 mm.

The anolyte was a 25% saline solution whose pH was controlled to 35, and the catholyte was an IN caustic soda solution.

Electrolysis was carried out at 50° C. for 3 hours, and the following results were obtained from the catholyte after electrolysis.

Applied voltage 5V, current density 14A/di, current efficiency 32%
, selectivity 98.0%.

The selectivity is the equivalent percentage of Na+ ions out of the increase in Na+ ions and CI- ions before and after electrolysis.

The state of the ion exchange membrane is the same as before the start of electrolysis.

Similar electrolysis was carried out with two membranes bonded together, with this ion exchange membrane on the acidic side and the cation exchange membrane Selemion CMV manufactured by Asahi Glass Co., Ltd. on the alkaline side.

The applied voltage was 9.5 V, the current density was 12.3 A/dm'', the current efficiency was 91%, and the selectivity was 99.9%.

When Selemion CMV comes into contact with an oxidizing atmosphere on the acidic side,
Although it is immediately oxidized and the ion exchanger peels off,
In this method, Selemion CMV did not change from its state before the start of electrolysis.

Claims (1)

[Scope of Claims] 1. An inorganic ion exchange membrane comprising at least one of iron, cobalt, nickel or manganese oxoacids and asbestos fibers. 2. Production of an inorganic ion exchange membrane characterized by coating or impregnating asbestos cloth, asbestos wool, asbestos board, etc. with a solution containing at least one of soluble salts of iron, cobalt, nickel, or manganese, and then treating with alkali. Method. 3. Adding asbestos fibers in a weight ratio to a solution containing at least one of soluble salts of iron, cobalt, nickel or manganese in units of iron, cobalt, nickel or manganese.
Cobalt, nickel or manganese/asbestos fiber - 5/9
A method for producing an inorganic ion exchange membrane, which comprises dispersing the membrane to a ratio of 5 to 75/25, and treating the membrane with an alkali after forming the membrane.