JP2004313780A - Electrolytic synthesis method of peracetic acid, and method and apparatus for sterilization wash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To electrically synthesize peracetic acid easily and economically, and to sterilize and wash containers of cold drinks and the like by using the obtained aqueous peracetic acid. <P>SOLUTION: The method for sterilization wash of a washed material 26 is done with acetic acid and/or acetates and oxygen-containing gas as raw materials by using solid acid catalysts and aqueous percarbonate which is obtained by electrolytic synthesis of peracetic acid with electrolysis cell 21. Herewith, peracetic acid is easily obtained at a low cost, and sterilization wash of the washed material is done effectively by using this peracetic acid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for electrolytically synthesizing peracetic acid, and a method and an apparatus for sterilizing an object to be cleaned using the peracetic acid.

Sterilization and cleaning of containers such as soft drinks and beer with peroxide-containing water such as hydrogen peroxide and peracetic acid, and disinfection of medical instruments such as endoscopes generate more trihalomethane than sterilization and cleaning with available chlorine. It is widely used as a method excellent in safety and environmental compatibility because it has no toxicity and has low toxicity even if it remains. Usually, a concentrated peracetic acid solution is transported to a factory, which is diluted and used for sterilization and cleaning.
Peracetic acid is an effective disinfectant for all microorganisms, including spores. A 0.2% aqueous solution of peracetic acid can kill spores in a shorter time than glutaral. There is little deactivation even in the presence of organic matter, and it is effective for spores even at low temperatures, and the lower the pH, the better the bactericidal activity. A solution of 2000 ppm or more has the ability to sterilize by contact at room temperature for 5 minutes.

Hydrogen peroxide also has a bactericidal effect and antimicrobial properties almost comparable to glutaral, and in Europe and the United States, 6% or more of stabilized hydrogen peroxide is used for disinfecting medical instruments such as endoscopes.
In order to discharge the water containing hydrogen peroxide after sterilization as wastewater, it is necessary to lower the TOC value in the biological treatment tank. In other words, if hydrogen peroxide remains, there is a risk that the activated sludge will be killed by its oxidizing power, and it is necessary to decompose the hydrogen peroxide to avoid this. For this decomposition, the use of various reducing agents is indispensable, leading to an increase in cost.

An example of a conventional method of sterilizing and cleaning an object to be cleaned using a peroxide will be described with reference to FIG.
In this conventional example, a peroxide such as peracetic acid or hydrogen peroxide is supplied to the chemical storage tank 1 and stored as an aqueous solution. Then, after the aqueous solution in the chemical liquid storage tank 1 is heated through the heating device 3 using the first circulation pump 2, the aqueous solution is supplied into the sterilization / cleaning chamber 5 containing the object 4 to be sterilized and cleaned, and 4 is sprayed using the nozzle 6.
A part of the peroxide aqueous solution after the sterilization and cleaning is circulated to the chemical solution storage tank 1 for reuse.
The sterilizing and cleaning chamber 5 is also connected to a reducing treatment tank 9 connected to a reducing agent tank 7 via a supply pump 8, and a peroxide aqueous solution that is not circulated to the chemical storage tank 1 is drawn out. In the reduction treatment tank 9, peracetic acid and hydrogen peroxide in the aqueous peroxide solution are decomposed by a reducing agent. The decomposed aqueous solution is circulated to the biological treatment tank 11 by the second circulation pump 10 to become a clear aqueous solution having a reduced TOC, and then discharged to a river or the like by the discharge pump 12.

In this conventional method of sterilizing and cleaning an object to be cleaned, for example, a concentrated peracetic acid solution (about 6%) is transported to a factory, and the concentrated solution is diluted (to 20 to 3500 ppm) and circulated for use (see FIG. 3). Chemical storage tank 1 → Heating device 3 → Sterilization / cleaning chamber 5 → Chemical storage tank 1).
At the time of this disposal, the aqueous peroxide solution in the sterilizing / cleaning chamber 5 is guided to the reduction treatment tank 9, and the remaining peroxide is reacted with a reducing agent to be neutralized and decomposed. After that, it is sent to the biological treatment tank, where the TOC value is reduced and discharged.
JP 2001-70412 A JP 2002-307081 A JP 2003-506120 A

The implementation of this method requires a large site and requires enormous processing costs. Further, since the concentrated peracetic acid solution as a raw material is transported from the outside, it is necessary to store or store the concentrated peracetic acid solution, which is not a safe method. There is also a drawback that a stabilizer must be added to prevent spontaneous decomposition of peracetic acid.
Patent document 1 discloses a medical sterilization method using an aqueous solution of a composition comprising peracetic acid and hydrogen peroxide, but does not disclose a method for synthesizing a bactericide on site. Further, Patent Document 2 discloses that activated carbon is used for peroxide decomposition, that organic substances can be recovered with an ion exchange resin, and that NF (nano filter), RO (reverse osmosis membrane), MF (membrane filter), and the like are used for separating dead bodies. This discloses that the sterilized water after treatment, which has been wastewater, can be recovered and used. However, even if acetic acid is recovered, it has to be discarded, leaving a fundamental problem.

As an on-site sterilizing water producing apparatus, electrolytic acidic water has recently been a hot topic. This electrolytic acid water has been approved by the Ministry of Health, Labor and Welfare as a disinfecting water with bactericidal activity (Notification No. 212 of the Ministry of Health, Labor and Welfare, June 10, 2002), and is being widely used as sanitary control water for hospitals and food factories. It has been reported that it also has a bactericidal effect against Legionella bacteria. However, these electrolyzed acidic waters are mainly hypochlorous acid-based germicides, have problems in ordinary use, and their safety remains questionable.
Peracetic acid having excellent properties as a fungicide is industrially synthesized by oxidizing acetaldehyde with oxygen activated at about 100 to 200 ° C. However, high-temperature operation is required, and on-site operation is difficult.

It is also known that peracetic acid can be synthesized by reacting hydrogen peroxide with acetic acid or acetic anhydride in the presence of an acid catalyst. However, this method uses sulfuric acid as an acid catalyst, and since the sulfuric acid is difficult to separate from the product, there is a concern about the safety when on-site.
By improving this method, an appropriate solid catalyst has been found from the viewpoints of separation characteristics, stability, reaction efficiency, and the like, whereby the separation from the product is facilitated and the safety is improved. However, in this method, although peracetic acid can be synthesized on site, it is necessary to store hydrogen peroxide, and it cannot be a simple sterilization treatment system.

Patent Document 3 describes a method for electrolytically synthesizing peracetic acid for the purpose of solving these disadvantages. In this method, oxygen gas is electrolyzed to obtain a peroxide species (for example, peroxide ion, peroxide radical, or hydrogen peroxide), and the peroxide species reacts with acetylsalicylic acid, which is a precursor of peracetic acid. To obtain peracetic acid. However, in this method, an expensive acetylsalicylic acid or the like is used as a peracetic acid precursor, and a peroxide species is once electrolytically synthesized and reacted with the peracetic acid precursor to synthesize peracetic acid. The process is long and is not economical.
Accordingly, the present invention provides a method for electrolytically synthesizing an aqueous solution containing peracetic acid having a high sterilizing and cleaning ability with a simpler method, particularly a method for on-site electrolytic synthesis, and further utilizing the electrolytically synthesized peracetic acid. It is an object of the present invention to provide a method and an apparatus for performing efficient sterilization cleaning.

  The present invention firstly provides a method for sterilizing and cleaning an object to be cleaned using an aqueous peroxide solution, comprising a peroxide containing electrolytically synthesized acetic acid and / or acetate and an oxygen-containing gas as raw materials. A method characterized in that the object to be cleaned is sterilized and washed using an aqueous solution. Second, electrolysis is performed while supplying acetic acid and / or an acetate and an oxygen-containing gas, and peracetic acid is removed at the cathode. An electrolytic cell for synthesizing an aqueous solution containing hydrogen peroxide, a sterilization cleaning chamber for bringing the aqueous solution produced by the electrolytic cell into contact with an object to be cleaned, A filter for filtering an aqueous solution of peroxide containing acetic acid-hydrogen peroxide to remove dead organisms in the aqueous solution, and means for circulating the aqueous solution of peroxide filtered by the filter to the electrolytic cell. And thirdly, electrolytically synthesizing peracetic acid using acetic acid and / or acetate and an oxygen-containing gas as raw materials using a solid acid catalyst. Is a method for electrolytic synthesis of peracetic acid.

Hereinafter, the present invention will be described in detail.
The present inventors have confirmed that peracetic acid can be electrosynthesized in one step with an inexpensive raw material, which is different from the method using the above-mentioned prior art expensive raw material and a two-stage electrolytic synthesis method. Furthermore, it has been found that the object to be washed can be sterilized and washed with high efficiency by sterilizing and washing the object to be washed with hydrogen peroxide, if necessary, together with hydrogen peroxide.
In other words, it was known that hydrogen peroxide can be efficiently synthesized by electrolytic reduction of oxygen. However, when electrolysis was performed using acetic acid as a raw material, it was found that hydrogen peroxide could be synthesized in this case as well. When a mixed solution of acetic acid and electrolytically synthesized hydrogen peroxide was brought into contact with a conventional solid acid catalyst, it was confirmed that peracetic acid could be synthesized.

Next, based on these findings, it was examined whether or not peracetic acid itself, which had not been reported before, could be synthesized. If this electrolytic synthesis is possible, peracetic acid can be synthesized efficiently and while controlling the concentration.
When the electrolytic cell was filled with a solid acid and electrolysis was performed using acetic acid as a raw material and supplying an oxygen-containing gas, it was confirmed that peracetic acid and hydrogen peroxide could be simultaneously synthesized.

In the oxygen reduction reaction in the electrolytic cell usable in the present invention, a reaction with an active species existing only on or near the active electrode surface, a direct electrolytic reaction, and a relatively stable chemical species such as hydrogen peroxide are used. Peracetic acid is synthesized by the indirect reaction of
The main reactions at the anode and cathode are as shown in formulas (1) and (2). Cathode is preferable to use a gas diffusion electrode is caused to proceed the reduction of oxygen easily occurs by electrolytic reduction O ₂ ^- or formula (3) reacts with generated active oxygen adsorbed species O ^* to the surface of such It is presumed that the direct oxidation reaction on the electrode proceeds. Further, as shown in the formula (4), it is considered that there is a part that is synthesized by reacting with hydrogen peroxide in a solution.

In the presence of the solid acid catalyst, the reaction of the formula (4) proceeds equilibrium, the bond between the oxygen atoms of hydrogen peroxide is broken by proton donation, and one OH radical reacts with the proton to form water. And the other reacts with acetic acid to form peracetic acid.
Further, when the catholyte and the anolyte are not separated, the hydrogen peroxide generated at the cathode has activity and is easily decomposed at the anode as shown in the formula (5). As a result, an aqueous solution containing the raw materials acetic acid or acetate and peracetic acid and containing only a small amount of hydrogen peroxide can be obtained.

Anode: 2H ₂ O = O ₂ + 4H ⁺ + 4e (1.23V) (1)
Cathode: O ₂ + 2H ⁺ + 2e = H ₂ O ₂ (0.683 V) (2)
Cathode: CH ₃ COOH + O ^* = CH ₃ COOOH (3)
H ₂ O ₂ + CH ₃ COOH + (H ⁺ ) = CH ₃ COOH (OH.) + H ₂ O = H ₂ O + CH ₃ COOOH + (H ⁺ ) (4)
_{H 2 O 2 = O 2 +} 2H + + e (0.68V) (5)

  The catalyst usable in the present invention is an acid catalyst, and it can be said that solid protonic acid is excellent in practicality from the viewpoint of easy separation. Examples of the protonic acid include a sulfone resin, and beads and granules of a resin polymer such as a sulfone resin commercially available under various trade names such as AMBERLYST (trade name) and DOWEX (trade name) can be used. The resin is composed of, for example, a polystyrene-divinylbenzene skeleton having a sulfone group as a functional group. However, since the styrene skeleton is easily decomposed by peracetic acid or hydrogen peroxide generated, it is inexpensive but has a disadvantage that it cannot withstand long-term use.

As a resin having excellent chemical resistance which can be substituted for the resin polymer, a fluororesin having a sulfone group as an ion exchange group (for example, Nafion (trade name) which is a commercially available product) can be given. Nafion is produced as a copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) -propyl] vinyl ether.
This resin preferably takes the form of powder or particles having a diameter of 0.01 to 3 mm. Nafion is particularly promising in terms of activity as a solid acid and chemical stability. It is presumed that the fluorinated carbon resin, which is the skeleton of Nafion, is chemically inert to active oxygen and peracetic acid generated, and decomposition hardly proceeds.
On the other hand, an organic-inorganic composite catalyst can also be used, and for example, a Nafion-silica composite can be prepared.

As a catalyst material having an ion exchange ability that can be used as a solid acid, in addition to the commercially available ion exchange resin particles as described above, there are styrene-based, acrylic acid-based, and aromatic polymer-based hydrocarbon-based resins. A fluorinated resin is preferred from the viewpoint of corrosion resistance. It is also possible to form a component having ion exchange ability on a suitable porous support member.
The porosity of the material is preferably 20 to 90% from the viewpoint of uniform dispersion of the liquid and the resistivity, and the size of the material particles is preferably 0.1 to 10 mm. The higher the amount of solid acid to be added, the higher the concentration of the product that can be obtained in a short time. However, in practice, there is a limit due to the limitation of the equipment cost. One to one tenth is preferred.

Catalysts for the oxygen gas cathode that promote the reaction between active oxygen and acetic acid and are suitable for generating hydrogen peroxide include platinum group metals or their oxides, carbon such as graphite or conductive diamond, or polyaniline or thiol (SH group). Organic matter). These catalysts may be used as they are in the form of a plate, or may be applied to a corrosion-resistant plate such as stainless steel, zirconium, silver, or carbon, a wire mesh, a powdered sintered body, a metal fiber sintered body, by a pyrolysis method, a resin fixing method, or a composite method. It is formed to have a thickness of 1 to 1000 g / m ² by plating or the like.
Metals such as carbon, nickel, and titanium, and alloys and oxides thereof can be used as the cathode power supply. In order to promptly supply and remove the reaction product gas and liquid, it is preferable to disperse and carry a hydrophobic or hydrophilic material. When a hydrophobic sheet is formed on the cathode back surface opposite to the anode, gas supply to the reaction surface can be controlled, which is effective.

The supply amount of oxygen to the cathode is preferably about 1.1 to 10 times the theoretical value. As the oxygen-containing gas of the raw material, air, oxygen-enriched air obtained by separating and concentrating air, and oxygen gas packed in a commercially available cylinder can be used. . The oxygen-containing gas is supplied to the gas chamber when the gas chamber exists on the back surface of the electrode, but may be absorbed by blowing into the electrolyte solution before the supply.
Examples of the anode catalyst include lead oxide, tin oxide, platinum, DSA, iron, graphite, conductive diamond, and the like. These catalysts may be used as they are, or may be used as a plate having corrosion resistance such as titanium, niobium, or tantalum, or a wire mesh. The powder is formed on a powder sintered body or a metal fiber sintered body by a thermal decomposition method, a fixing method using a resin, composite plating, CVD, or the like so as to have a weight of 1 to 500 g / m ² .
The material that can be used as the electrode substrate needs to have corrosion resistance so as not to cause contamination of the treated surface from the viewpoint of long life, and it is preferable to use a valve metal such as titanium or its alloy as the anode power supply. .

The usual anodic reaction is oxygen generation, but in the present invention, the amount of peracetic acid generated is increased by adjusting the type of anode and electrolysis conditions. In addition, by appropriately selecting the anode catalyst, an oxidation reaction for decomposing organic substances in the collected acetic acid aqueous solution into inorganic substances (carbon dioxide, carbonate ions) also progresses, which can contribute to maintaining the quality of circulating water.
When the electrolytic cell is partitioned into an anode chamber and a cathode chamber by the diaphragm, each ion generated at the anode and the cathode is prevented from being consumed at the counter electrode, and the active substance generated by the electrolytic reaction is stably maintained. It has the function of promptly proceeding electrolysis even when the conductivity is low. Examples of usable membranes include neutral membranes and ion exchange membranes. The ion exchange membrane may be either a fluororesin type or a hydrocarbon resin type, but the former is preferred from the viewpoint of corrosion resistance.
On the other hand, it is also possible to perform electrolysis without attaching a diaphragm and selectively oxidize and decompose hydrogen peroxide generated at the anode to adjust the concentration ratio of peracetic acid to hydrogen peroxide.

Among the electrolysis conditions, the higher the temperature, the higher the reaction rate increases and reaches equilibrium in a short time, but the decomposition rate also increases. Therefore, it is desirable to control the temperature to be higher than room temperature and lower than 60 ° C. as an appropriate temperature range. The current density is preferably 0.1 to 100 A / dm ² . The distance between the electrodes is preferably as small as possible to reduce the resistance loss, but is preferably 1 to 50 mm in order to reduce the pressure loss of the pump during water supply and keep the pressure distribution uniform.
The concentrations of the generated hydrogen peroxide and peracetic acid can be controlled to 50,000 ppm (5% by weight) by adjusting the amount of water and the current density. This concentration adjustment may be performed by combining positive and negative electrodes having different catalysts.
In order to improve the reaction efficiency, it is preferable to appropriately control and maintain the electrolytic solution to be acidic, that is, pH 2 to 6. If it is acidic, even if tap water is used as raw water, Ca ions and Mg ions contained in the tap water are advantageous because their hydroxides and carbonates do not precipitate on the cathode.

  If the feed rate of the raw water is slowed down and the contact time is multiplied, the synthesis reaction of peracetic acid can theoretically proceed until the equilibrium value is reached, but the synthesis can be continuously performed within a practical time range. It is desirable to carry out the process, and a large amount of the raw material remains in the product. In the present invention, acetic acid or acetate is used as a raw material, and the production rate of peracetic acid increases as the concentration thereof increases. However, in consideration of the safety of handling the generated peracetic acid and hydrogen peroxide, the concentration of peracetic acid and hydrogen peroxide in the raw material aqueous solution is preferably 5% or less. The concentration range of the germicidal washing water used for circulation is preferably 100 to 10,000 ppm for raw material acetic acid, 10 to 4000 ppm for peracetic acid, and 10 to 20,000 ppm for hydrogen peroxide.

As the electrolytic cell material, a glass lining material, carbon, titanium, stainless steel, PTFE resin, or the like having excellent corrosion resistance can be preferably used from the viewpoint of ensuring durability and stability of hydrogen peroxide.
The raw materials used in the present invention include, in addition to free acetic acid, acetates such as sodium acetate and potassium acetate. The object to be cleaned by the sterilization cleaning method of the present invention is not particularly limited, but includes containers for soft drinks and beer, and medical instruments such as endoscopes.

The present invention provides a method for sterilizing and cleaning an object to be cleaned using an aqueous peroxide solution, wherein a peroxide aqueous solution containing peracetic acid electrolytically synthesized using acetic acid and / or acetate and an oxygen-containing gas as raw materials is used. And sterilizing and cleaning the object to be cleaned.
According to the method of the present invention, peracetic acid can be synthesized from inexpensive acetic acid or acetate, and beverage containers and the like can be efficiently sterilized and washed with sterilized washing water containing peracetic acid.

In addition, if the sterilized washing water after the sterilizing washing is circulated to the electrolytic cell, the sterilized washing water containing peracetic acid, which had been conventionally discharged, is circulated and reused in the electrolytic cell, so that the discharged water deteriorates the living environment. Can be prevented, and the TOC value does not need to be reduced.
Further, in the apparatus of the present invention in which a filter for filtering impurities such as dead bodies of living organisms is installed, the purity of the aqueous peroxide solution circulated to the electrolytic cell is further improved, the electrolytic efficiency is increased, and troubles of the electrolytic cell due to the impurities are reduced. Can be prevented.

If a concentration sensor is installed in the circulation line, the concentration of peracetic acid is continuously measured, and the amount of power supplied to the electrolytic cell is adjusted according to the magnitude of the measured value to maintain the concentration of peracetic acid within a certain range. A desired sterilizing and cleaning effect can be obtained.
Furthermore, in the method of the present invention, peracetic acid can be easily electrolytically synthesized using inexpensive acetic acid or acetate as a raw material, and is a revolutionary method for producing peracetic acid.

  Next, an embodiment of sterilization cleaning by peroxide according to the method of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic view showing an embodiment of a sterilization and cleaning method using a peroxide of the method of the present invention, and FIG. 2 is a schematic longitudinal sectional view of an electrolytic cell used in FIG.
In this embodiment, peracetic acid is synthesized in the electrolytic cell, and the peroxide aqueous solution after the object to be cleaned is sterilized and washed is circulated to the electrolytic cell for reuse.

As shown in FIG. 2, the electrolytic cell 21 of FIG. 1 has an anode 41 made of an expanded mesh or the like, a sheet-shaped oxygen gas cathode 42, and a diaphragm 43 that separates the anode chamber and the cathode chamber. The cathode solution chamber between the diaphragms 41 is filled with solid acid catalyst particles 44 such as Nafion resin or a fibrous catalyst material, and the distance between the electrodes is maintained at about 1 to 50 mm. In FIG. 2, 45 is an anode gas outlet, 46 is a catholyte inlet, and 47 is a catholyte outlet.
The electrolytic cell 21 is supplied with oxygen gas from an oxygen supply device 22 for preparing high-purity oxygen by the PSA method, and is supplied with a peracetic acid solution or a mixed solution of hydrogen peroxide supplemented with acetic acid from a storage tank 23. In the cell 21, peracetic acid and hydrogen peroxide are generated from the acetic acid. The germicidal washing water (aqueous peroxide solution) containing peracetic acid-hydrogen peroxide is heated by the heating device 25 after the concentration sensor 24 detects the concentrations of peracetic acid and hydrogen peroxide.

After the concentration is detected, the germicidal washing water is supplied into a germicidal washing chamber 27 containing an object 26 to be sterilized and washed, and sprayed onto the object 26 using a nozzle 28. The germicidal washing water after the germicidal washing is guided by the first circulation pump 29 from the germicidal washing chamber 27 to the decomposition product removal filter 30, which removes dead bodies of organisms and other impurities. Thereafter, the sterilizing and washing water is stored in the storage tank 23, and after replenishing the consumed acetic acid as needed, is circulated to the electrolytic cell 21 by the second circulating pump 31 for reuse.
In the present embodiment, the sterilizing washing water containing peracetic acid, which has been conventionally discharged, is circulated and reused in the electrolytic cell, so that it is possible to prevent the deterioration of the living environment due to the discharge, and to use inexpensive acetic acid or acetate. Can be synthesized from acetic acid, and it is not necessary to further reduce the TOC value.

  Next, examples relating to the sterilization and cleaning method using a peroxide according to the present invention will be described, but these do not limit the present invention.

[Example 1]
Iridium oxide was coated on a titanium porous plate at a concentration of 10 g / m ² by a thermal decomposition method to form an anode. A graphite powder (TGP-2, manufactured by Tokai Carbon Co., Ltd.) is kneaded with a PTFE resin as a catalyst, applied on a carbon cloth (PWB-3, manufactured by Zoltec) as a core material, and baked at 330 ° C. to 0.5 mm. A thick sheet was prepared and used as an oxygen gas cathode. The ion exchange membrane Nafion (trade name) 117 (manufactured by DuPont) was used for the membrane, and the distance between the membrane and the oxygen gas cathode was 5 mm. Nafion resin (manufactured by DuPont NR-50) was used between the membranes (gas chamber). Was charged. The distance between the ion exchange membrane and the anode was set to 0 mm, and an electrolysis cell having an electrolysis effective area of 100 cm ² was formed.
When the temperature was set to 25 ° C., a current of 10 A was passed while supplying 200 ml of air to the gas chamber per minute and an aqueous solution of acetic acid (5 M CH ₃ COOH, pH 3) to the anode and cathode chambers of the cell at 10 ml per minute. And the cell voltage was 8V. The concentration of hydrogen peroxide in the cathode outlet solution was measured by KMnO ₄ titration, and the concentration of peracetic acid was measured by an HPLC liquid chromatograph. As a result, it was found that 240 ppm of peracetic acid and 1200 ppm of hydrogen peroxide were obtained.

[Example 2]
Electrolysis was carried out in the same manner as in Example 1 except that a non-separated membrane type electrolytic cell from which the ion exchange membrane as a diaphragm was removed, was found to have a cell voltage of 8V. At the cathode compartment outlet, 220 ppm of peracetic acid and 100 ppm of hydrogen peroxide were obtained.

[Example 3]
Electrolysis was carried out in the same manner as in Example 1, except that graphite powder containing 0.5 mg / cm ² of platinum was used as a catalyst for the oxygen gas cathode. As a result, the cell voltage was 7.5 V. The concentration of hydrogen peroxide in the cathode outlet solution was measured by KMnO ₄ titration, and the concentration of peracetic acid was measured by an HPLC liquid chromatograph. As a result, 600 ppm of hydrogen peroxide and 800 ppm of peracetic acid were obtained.

[Example 4]
Electrolysis was performed in the same manner as in Example 1 except that the current value was set to 20 A and air was supplied to the gas chamber at 500 ml / min. As a result, the cell voltage was 7.5 V. At the cathode compartment outlet, 300 ppm of hydrogen peroxide and 800 ppm of peracetic acid were obtained. Comparison between Example 1 and Example 4 shows that the concentration ratio of hydrogen peroxide and peracetic acid can be adjusted by the current density.

[Example 5]
The circulation line shown in FIG. 1 was assembled using the electrolytic cell of Example 1 (the concentration sensor was not installed). The aqueous peroxide solution having the concentrations of hydrogen peroxide and peracetic acid obtained in Example 1 was brought into contact with the object to be cleaned in the sterilization cleaning chamber for 1 minute, and then collected. The recovered aqueous peroxide solution contained about 1000 cells / ml of dead bacteria, but after passing through a UF filter, the number of bacteria became zero.

[Example 6]
The concentration of the peracetic acid and hydrogen peroxide was reduced by half by diluting the cathode outlet liquid obtained in Example 1 twice (120 ppm of peracetic acid and 600 ppm of hydrogen peroxide). When this diluted water was supplied to the electrolytic cell of Example 1 for electrolysis, the concentration of peracetic acid and hydrogen peroxide in the cathode outlet solution was about 240 ppm for peracetic acid and about 1200 ppm for hydrogen peroxide, which were equal to the values before circulation. Was. This indicates that the peroxide aqueous solution can be circulated.

[Example 7]
Using the electrolytic cell of Example 1, a circulation line including the concentration sensor shown in FIG. 1 was assembled, and the current value of the electrolytic cell was varied while detecting the concentration of peracetic acid with the concentration sensor. When the system was operated continuously for approximately 1000 hours while maintaining the temperature almost constant, the concentration of peracetic acid in the sterilizing washing water sent to the sterilizing washing chamber could be maintained at 250 to 300 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows one Embodiment of the sterilization washing | cleaning method by the peroxide of the method of this invention. FIG. 2 is a schematic longitudinal sectional view of the electrolytic cell of FIG. 1. The schematic diagram which shows one Embodiment of the sterilization cleaning method by the conventional peroxide.

Explanation of reference numerals

21 Electrolysis cell
22 Oxygen supply device
23 Storage tank
25 Concentration sensor
26 Items to be cleaned
27 Cleaning chamber
28 nozzles
30 Decomposition removal filter
41 anode
42 Oxygen gas cathode
43 diaphragm
44 Solid acid catalyst particles

Claims (5)

  In the method of sterilizing and cleaning an object to be cleaned using an aqueous peroxide solution, the object to be cleaned is washed using a peroxide aqueous solution containing peracetic acid electrolytically synthesized using acetic acid and / or acetate and an oxygen-containing gas as raw materials. A method characterized by sterilizing and washing an object.   The method for sterilizing and cleaning with peroxide according to claim 1, wherein the aqueous solution of peroxide after sterilizing and cleaning the object to be cleaned is reused for electrolytic synthesis.   An electrolysis cell for performing electrolysis while supplying acetic acid and / or acetate and an oxygen-containing gas to synthesize an aqueous solution containing peracetic acid and hydrogen peroxide at a cathode, and applying the aqueous solution produced by the electrolysis cell to an object to be cleaned. A germicidal washing chamber for contacting, for filtering an aqueous peroxide solution having peracetic acid-hydrogen peroxide from the germicidal washing chamber, which is present downstream of the chamber, for removing biological dead bodies in the aqueous solution; A sterilizing and cleaning apparatus using peroxide, comprising: a filter; and means for circulating a peroxide aqueous solution filtered by the filter to the electrolytic cell.   The sterilizing and cleaning apparatus according to claim 3, wherein a sensor for measuring a concentration of peracetic acid in the aqueous peroxide solution is provided in the circulation line.   An electrolytic synthesis method of peracetic acid, wherein peracetic acid is electrolytically synthesized using acetic acid and / or an acetate and an oxygen-containing gas as raw materials using a solid acid catalyst.

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