JPS5923842B2 - electrodialysis machine - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrodialysis device.

More specifically, the present invention relates to an electrodialysis device that has an energy-saving configuration that does not require an external power supply and is useful for seawater desalination, food desalination processing, and the like.

Conventionally, electrodialysis devices that combine an ion-permeable membrane and an electrolytic cell have been used to concentrate and/or dilute an electrolyte solution (membrane electrolyte).
It is used for various purposes.

Among these, a schematic diagram of a multiple ion-permeable membrane type electrodialysis device is shown in FIG.

Figure 1 shows an example of a sodium chloride solution as an electrolyte solution, and the sodium chloride solution from the concentrated solution 5 is applied to an anion-permeable membrane A and a cation-permeable membrane K alternately stretched in a treatment tank 2. It is introduced into the concentration chamber 0, which is divided into sections.

- power, diluent population 4, sodium chloride solution in dilution chamber 0
It will also be introduced.

In this state, when a DC voltage is applied to the electrodes 6 and 7 in the processing tank, sodium ions (Na are drawn toward the cathode e,
Chlorine ions (C1-) are drawn toward the anode ■, but Na+ and C1- in the dilution chamber [F] are drawn to the adjacent concentration chamber O through the cation-permeable membrane K and the anion-permeable membrane A, respectively.
Transparent transition to.

- Na+ and C1- in the concentration chamber cannot pass through due to the action of K and A, and do not migrate to the dilution chamber (see arrow in the figure).

That is, the sodium chloride concentration in the dilution chamber 0 decreases, and the sulfur chloride concentration in the concentration chamber c increases.

Therefore, the electrolytic chamber solution will be concentrated and/or diluted.

However, in the conventional apparatus as described above, it is necessary to continuously supply DC voltage from the outside to the electrodes 6 and 7 in the processing tank, which is disadvantageous in that it requires high electric power and increases operating costs.

The present invention has been made to eliminate these drawbacks, and provides an energy-saving electrodialysis device that does not require an external power supply.

Thus, according to the present invention, an anion-permeable membrane and a cation-permeable membrane are alternately stretched and partitioned in a treatment tank, and two types of porous materials having different oxidation ring potentials are placed near both surfaces of each membrane. By providing the layers regularly and short-circuiting each of the two porous material layers outside the processing solution,
Provided is an electrodialysis device that does not require an external power source and is characterized in that it includes a dialysis element that alternately generates a concentrated electrolyte-containing solution and a parent electrolyte solution.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic diagram showing a specific example of the electrodialysis apparatus of the present invention.

In FIG. 2, an anion-permeable membrane A and a cation-permeable membrane each having an aluminum porous layer 1a and a silver stripe porous layer 1b having different oxidation ring potentials adhered to both sides by vapor deposition each have a rectangular shape. These membranes and the processing tank are arranged alternately at predetermined intervals in the body-shaped processing tank 2, and a large number of concentration chambers 0 and dilution chambers [F] are formed by these membranes and the processing tank.

The aluminum porous chamber layer 1a and the auspicious silver porous chamber layer 1b regularly adhered to both surfaces of the ion-permeable membrane are electrically connected outside the processing tank 2 by short-circuit portions 3 each consisting of a wire connection.

Further, the concentration chamber O and the dilution chamber 0 are connected to a concentrate port 5 and an outlet 5', and a dilute solution port 4 and an outlet 4', which are similar to those shown in FIG. 1, through inlet pipes.

In the above configuration, l-I chloride is used as the electrolyte.
The function when using Jum will be explained.

First, a sodium chloride solution is introduced into the concentration chamber 0 and the dilution chamber 0 through the concentrated solution 5 and the diluted solution 4, as in the conventional case.

In this state, the aluminum porous layer 1a and the silver striped porous layer 1b closely adhered to each ion exchange membrane are immersed in the electrolyte solution, exhibiting different potentials and generating a potential difference between them.

For example 0. Chloride of IN I-1) A potential difference of about 600 mV occurs in the rum solution.

Based on this potential difference, a current flows through the short-circuit portion 3, and both layers maintain the polarized state as shown in FIG.

Therefore, Na+ in the dilution chamber 0 passes through the aluminum porous layer 1a and the cation permeable membrane K as shown by the arrow and moves to the vicinity of the silver striped porous layer 1b immersed in the concentration chamber O in the adjacent chamber.
Further, CI- similarly passes through the silver striped porous layer 1b and the anion-permeable membrane A and moves to the vicinity of the aluminum porous layer 1a immersed in the concentration chamber O in the adjacent room.

- Na+ and CI'- in the concentration chamber remain as they are in the concentration chamber due to the electrical action of the porous layer and the action of the respective ion-permeable membranes.

That is, the behavior of Na+ and C1- within each compartment is the same as before.

Therefore, the electrolyte solution can be concentrated and/or diluted in the same manner as before without requiring an external power source.

The two porous material layers having different oxidation ring potentials in this invention are not limited to those made of metals such as those mentioned above, but are made of materials that produce a sufficient potential difference at least when immersed in an electrolyte solution. Any combination may be used, and various metals, conductive substances, etc. can be used.

Furthermore, the porous material may be porous as long as the target ions can pass therethrough, and may be mesh-like.

Further, as the anion-permeable membrane and the cation-permeable membrane, various types known in the art can be used, such as various anion-exchange membranes and cation-exchange membranes having ion selectivity.

The two porous material layers may be placed on both sides of the ion-permeable membrane or in the vicinity, but it is usually preferable to form them in close contact with both sides by a method such as vapor deposition or sputtering to increase efficiency and improve efficiency. It is preferable in terms of ease of handling and the like.

Further, in the present invention, the short-circuit portion may be made of a material with relatively low electrical resistance and has no power supply element, and may be, for example, a short-circuit portion that penetrates the end of the membrane and is fixed with a bolt and nut.

In addition, an ammeter or the like may be inserted into this short circuit to manage the operating status, but as long as the impedance of these is small, the desired electrodialysis phenomenon will occur, so it will be considered that there is a short circuit. .

The electrodialysis apparatus of the present invention can be applied not only to seawater desalination but also to desalination of foods such as milk and soy sauce, water electrolysis, alkaline electrolysis, etc., and has the advantage that no external power is required for any of them. Useful.

Moreover, it is suitable for electrodialysis in places where it is difficult to obtain electric power, such as ships and remote islands.

Hereinafter, the present invention will be explained in more detail by showing examples.

Example 1 Concentration chamber O/dilution chamber [F] as shown in the cross section in Fig. 3
An electrodialysis apparatus of the present invention was fabricated, which consists of a processing tank equipped with 0 concentration chambers.

The ion-permeable membranes include ion-exchange resin membranes such as cation-selective membrane K (for example, Nafion, a trade name of DuPont) and anion-selective membrane A (for example, Selem).
ion ASV (trade name of Asahi Glass)), and an aluminum net 1'a and a silver net 1'b were closely attached to each of these ion-permeable membranes in the arrangement shown in the figure.

The aluminum net 1'a and the silver net 1'b are connected to each other by a short-circuit portion 3 made of copper wire outside the processing tank 2.

Further, 12 is a stirrer.

Approximately 0.00 mm inside each compartment of the above configuration. A sodium chloride solution of IN was introduced and dialysis was performed.

In this case, the potential difference between the aluminum net 1'a and the silver net 1'b was about 0.66V.

The change over time in the CF concentration in the dilution chamber [F] obtained as a result of the above dialysis was as shown by the broken line P in FIG.

Incidentally, as a corresponding prior art method, when a voltage of 1.5 V is intentionally applied from the external power supply 13 using a device as shown in FIG. 4, the result of the change in CI□ concentration over time is as shown by the solid line Q. became.

Although both FIG. 3 and FIG. 4 show only the change in the C1- concentration, the change in the Na+ concentration was also exactly the same.

These results clearly show that the electrodialysis effect of the device of the present invention is equivalent to that of conventional electrodialysis using external power.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a conventional electrodialysis apparatus. FIG. 2 is a schematic diagram showing a specific example of the electrodialysis apparatus of the present invention. FIG. 3 is a sectional view of essential parts showing another specific example of the electrodialysis apparatus of the present invention. FIG. 4 is a third diagram showing another specific example of the conventional electrodialysis device.
It is a sectional view of the main part corresponding to the figure. FIG. 5 is a graph showing an example of the dialysis effect of the present invention. 1a...Aluminum porous layer, 1'a...
...Aluminum net, 1b...Silver striped porous layer, 1'b...Silver net, 2,2'...Processing tank, 3... ...Short circuit, 4...Diluted liquid inlet, 5...Concentrated liquid inlet, 4'...Diluted liquid outlet, 5'...Concentrated liquid outlet , 6...
Anode, 7...Cathode, 8...Anode chamber liquid,
9...Cathode chamber liquid, 10...Anode chamber, 1
1... Cathode chamber, 12... Stirrer, 13
...External power supply, A...Anion permeable membrane, K...Cation permeable membrane, O...
Concentration chamber, 0... Dilution chamber, P... Change over time due to the device of the present invention, Q... Change over time due to the conventional example.

Claims (1)

[Claims] 1. A treatment tank is partitioned by alternately extending anion-permeable membranes and cation-permeable membranes, and two types of porous membranes having different oxidation ring potentials are formed near both surfaces of each membrane. By providing regular material layers and short-circuiting each of the two types of porous material layers outside the treatment solution, a dialysis element is constructed that alternately produces a concentrated electrolyte-containing solution and a demolded electrolyte solution. An electrodialysis device that does not require an external power source. 2. The device according to claim 1, wherein the anion-permeable membrane and the cation-permeable membrane comprise an anion-exchange resin membrane and a cation-exchange resin membrane having ion selectivity. 3. Claims 1 or 2, wherein two types of porous material layers having different oxidation ring potentials are formed in close contact with both sides of an anion-permeable membrane and a cation-permeable membrane by vapor deposition or sputtering, respectively. The device described in.