JPS5813630B2 - Electrolytic chlorine gas generation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for generating chlorine gas in a chlorine gas generator used in water treatment equipment and the like.

Previously, the applicant proposed a water pumping system as described in Japanese Patent Publication No. 44-16990, which uses chlorine gas to pump drinking water or industrial water from a well, reservoir, river, etc. using a motor pump system. The sterilizer includes a chlorine gas generator, which generates chlorine gas by electrolyzing the electrolyte by applying electricity, and mixes the generated gas into the pumped water using a mixing device. However, N is used as the electrolyte.
a When a Cl aqueous solution is used, as Cl2 is generated, N
a Excess Na+ in Cl makes the solution alkaline, reducing electrolytic efficiency and Cl2 gas generation ability, and chlorine gas is no longer generated.

Furthermore, injecting chlorine from a chlorine cylinder has the problem of storing hazardous materials and is dangerous in handling, making it unsuitable for simple household use.

In addition, there is a Cl2 gas generation method by electrolysis of a MgCl2 saturated aqueous solution instead of the NaCl solution, but since the generated Mg(OH)2, which is equivalent to the amount of chlorine generated, has a low solubility, Cl2
Competitive reactions for the generation of 02 and 02 gases are very small compared to the case of NaCl, but the redissolution of Cl2 and Mg(CH)2
The colloidal dispersion of these materials coagulates and solidifies on the electrodes and the electrolytic cell, resulting in increased resistance and difficulty in removal from the cell.

Taking these points into consideration, the present invention divides one electrolytic cell into an anode chamber and a cathode chamber with an anion exchange membrane, and the anode chamber liquid is made of NaC.
l: Filled with an aqueous solution in which a metal chloride capable of forming an amphoteric oxide is added to NaCl3, such as a saturated aqueous solution of AlCl3 in a weight ratio of 50:1 to 10:1.The cathode chamber liquid contains the metal chloride and A saturated aqueous solution containing a mixture of the metal chloride and an organic acid such as tartaric acid or gluconic acid capable of forming chain salts or double salts in a molar ratio of 1:3 or more. It is designed to be filled and electrolyzed.

The method of the present invention will be explained with reference to an embodiment of the apparatus shown in the drawings for carrying out the method of the present invention.

Reference numeral 1 designates one electrolytic cell, in which an anode chamber 2 having an anode 2a made of graphite or the like and a cathode chamber 3 having a cathode 3a also made of graphite or the like are separated by an anion exchange membrane 4 in the center.

5 is the anode chamber solution with NaCl:AlCl3 of 50:1 to 10
: It is a saturated aqueous solution that can be mixed in a ratio of 1:1.

6 is the cathode chamber liquid, which is F e having the ability to form amphoteric oxides.
A mixture of a metal chloride such as Cl 2 or Al C ls and an organic acid such as tartaric acid or gluconic acid that has the ability to form a complex or double salt with the metal constituting the metal chloride. It consists of a saturated aqueous solution having a mixing ratio of 1:3 or more in molar ratio.

Thus, when no voltage is applied, both chambers 2 and 3 are partitioned and the liquids 5 and 6 in both chambers do not mix;
, 3a, electrolysis is performed, and Cl2 gas is generated from the anode chamber 2 and H2 gas is generated from the cathode chamber 3. This can be used, for example, in a pumped water sterilization chlorine gas generator as described in the above-mentioned publication. It is used.

The present invention is an improvement in the case where NaCl is used as a chloride electrolyte to generate and supply chlorine gas in an electrolytic chlorine gas generator that is used intermittently over a long period of time, and an anion exchange membrane 4 is provided. The Na+ in the anode chamber 2 generated with the generation of Cl2 gas by electrolysis is removed by the exchange membrane 4.
The Cl2 gas entering from the cathode chamber 3 through the Cl2 gas is neutralized, preventing the alkalization of the anode chamber 2 and allowing efficient generation of Cl2 gas to continue without reducing electrolysis efficiency, while the above-mentioned neutralization This is advantageous in that the exchange membrane, which has low corrosion resistance against alkali, is protected, and dissolved substances in the cathode chamber 3 are less likely to permeate and diffuse into the anode chamber 2 through the anion exchange membrane 4 when electricity is not applied.

In addition, in the anode chamber 2, 50:1 to 10:1 to NaCl was added.
The reason why metal chlorides such as AlCl3 and FeCl2 are added at a ratio of 1 is because the permeability of Cl- supplied from the cathode chamber 3 to the anode chamber 2 via the exchange membrane 4 by electrolysis with respect to the current is 1:1.
1, and for this reason, the anode chamber tends to become Na+-rich alkalized because the above chloride supplies Cl-, and since it is both acidic, it acts as an acid by itself. It acts to neutralize Na+4 and prevents a decrease in electrolytic efficiency due to alkalinization of the anode chamber 2 during long-term electrolysis.

Further, in the cathode chamber 3, an organic acid such as tartaric acid or gluconic acid that has the ability to form a complex salt or double salt with the metal of the metal chloride is mixed in a molar ratio of 1:3 or more, that is, a sufficiently large proportion of the organic acid. is generated by supplying Cl- to the anode chamber 2
The purpose is to prevent an increase in metal ions such as or Fe by forming a complex salt or double salt between the metal and an organic acid, and to continue supplying Cl from the cathode chamber 3, and to form the above complex salt or double salt. In order to achieve this, it is necessary to mix the above molar ratios.

That is, in this cathode chamber 3, A is used which generates Cl- by electrolysis and supplies said Cl- to the anode chamber 2 through the anion exchange membrane 4.
It would be good if there were metal chlorides such as iCl3 or FeC132, but if only AlCl3 or FeCl2 is used, AA(OH)3 and Fe(OH) are released due to the release of Cl-.
2, etc. are generated, and colloidal precipitates are generated as in the case of MgCl2 aqueous solution electrolysis, but this also coagulates and solidifies on the electrodes and electrolytic cell, adheres, etc., and causes drawbacks such as increased current carrying resistance and difficulty in cleaning. However, if organic acids that form complex acids and double salts are mixed to form complex acids and double salts as described above, the above-mentioned precipitates and deposits will not be generated, and the above-mentioned drawbacks can be prevented. Because you will get it.

Metal chloride mixed into the anode chamber 2 and cathode chamber 3,
As for the organic acid mixed into the cathode chamber 3, at least when this chlorine gas generator is used for sterilizing drinking water, the products produced as a result of electrolysis and the organic acids themselves are contained in the water along with steam, etc. Of course, it is necessary to select and use materials that are not harmful to the human body or human resources.

For example, in the electrolytic chlorine gas generation method of the present invention, Zn. nb group including Cd, Hg, Al, Ca . Ib group including In, Tl,
The IXb group including Ge, Sn, and Pb, the Fe group including Fe, Co, and Ni, and chlorides of metals such as Be and Cr can be used, but when the target of treatment is drinking water, etc., Zn
The use of chlorides such as , Cd, Hg, Sn, Pb, Be and Cr must be avoided.

This also applies to organic acids that have the ability to form complex salts or double salts with the metals constituting the metal chloride.
) In addition to hydroxyl group-containing organic acid compounds typified by tartaric acid, (2) amino- or imino-containing organic acid compounds typified by EDTA, (3) sulfur group-containing organic acid compounds typified by thioglycolic acid, and ,(
4) Other organic acid compounds such as phytic acid and humic acid can also be used in principle, but organic acids belonging to (3) and (4) above may contain harmful substances during electrolysis. It is difficult to use it widely and generally because there are problems such as some things being generated.

Next, the present invention will be explained with examples. NaCl: 3
0 0 g/l and AlCl3: 1000 ml of an aqueous solution of 30 g/l adjusted to pH approximately 1.1 with HCl and NaOH was placed in the anode chamber, and 400 g/l of lactic acid and Al
An aqueous solution of Cl3120g/l was mixed with HC6 and NaO.
Fill the cathode chamber with a solution whose pH has been adjusted to approximately 2.0 with H, and
A 4 mm ψ x 300 mm ferrite electrode was installed as an anode in the anode chamber so that the immersion length was approximately 100 mm, and a 70 mm x 70 mm x 10 cm (
Immerse the graphite electrode of t) in the cathode chamber as a cathode,
The opposing gap between the two electrodes via the exchange membrane is set to about 30 mm.

The anion exchange membrane is manufactured by Company A and has the following properties: base material: styrene-butadiene, exchange group: quaternary ammonium, electrical resistance: 3 to 4 Ωd, and transport number of 0.92 or more (however, 0.5N.NaCl). was used with a membrane area of about 95 cm'.

Forced cooling was performed to maintain the temperature at approximately 23 to 25°C, and electrolysis was performed at a voltage of approximately 5.2 V. The current density at the anode was approximately 10 A.
/dm2, cathode: approximately 8 A/dm2, anion exchange membrane: approximately 4 A/dm2.

When the amount of electricity for electrolysis was approximately 20 AH, and the amount of chlorine gas generated was investigated, the following results were obtained.

That is, the pH of the aqueous solution in the anode chamber is approximately 1.3, and the liquid volume change is approximately +1.
2 ml (+1.2%), the pH of the aqueous solution in the cathode chamber is approximately 3.6, and the liquid volume change is approximately -18 ml (-1.8
%), and the current efficiency Ceff was 98.9% or more.

In order to protect the anion exchange membrane, it is desirable to maintain the anode chamber and the cathode chamber at equal pressure. Therefore, if the gas reservoir spaces at the top of each chamber in the electrolytic cell are configured to communicate with each other, this Since permeation/diffusion or exchange with the liquid in other chambers occurs in some parts, it is better to completely separate chambers 2 and 3 in tank 1 and conduct gas extraction so that the gas pressures in each chamber are approximately equal. .

For example, in the case described in the above publication, H2 generated in the cathode chamber
Although gas is not necessary, if the gas outlet pipes led out from each chamber are connected to the aspirator section individually or together in the middle to suck out the generated gas, pressure will not be applied to the exchange membrane and the service life will be shortened. There is no.

As described above, according to the chlorine gas generation method of the present invention, Na is used as a chloride electrolyte to generate and supply chlorine gas by electrolysis.
It is possible to obtain an electrolytic chlorine gas generator that has high electrolysis and gas generation efficiency when using C 1 and can be used for a long period of time.

[Brief explanation of drawings]

The figure is a side sectional view of an embodiment of an apparatus for carrying out the method of the present invention. 1 is an electrolytic cell, 2 is an anode chamber, 3 is a cathode chamber, 4 is an anion exchange membrane, 5 is an anode chamber liquid, and 6 is a cathode chamber liquid.

Claims (1)

[Claims] 1 An anion exchange membrane electrolytic cell is used, the anode chamber is filled with an aqueous NaOl solution containing at least one of the chlorides of the mb group and iron group metals in the periodic table, and the cathode chamber is filled with the above-mentioned chlorides. An aqueous solution containing a metal chloride and at least one carboxylic acid selected from a hydroxyl group-containing carboxylic acid and an amino group-containing carboxylic acid or an imino group-containing carboxylic acid capable of forming a complex or double salt with the metal constituting the metal chloride. An electrolytic chlorine gas generation method characterized by recovering chlorine gas from an anode chamber by filling the anode chamber with electrolysis.