JP7323230B2 - Method for generating combined chlorine - Google Patents

Description

The present invention relates to a method for producing combined chlorine compounds.

In water systems such as cooling water systems, circulating baths, and water used in the pulp and paper manufacturing process, slime composed of bacteria, fungi, algae, etc., occurs in the system, reducing heat transfer efficiency, clogging pipes, and causing metal material damage. It often causes microbial disorders such as corrosion. Free chlorine and combined chlorine agents have been used to suppress the generation of such slime and to reduce the generated slime.
As a method using free chlorine, there are many methods that generate free chlorine using hypochlorite, etc., but the decomposition of hypochlorite is accelerated by ultraviolet rays and copper and iron ions eluted from piping materials. Because of this, the active ingredients decrease quickly, and the effect is not constant.

As a type using a combined chlorine agent, a method using chloramine, chlorinated hydantoin, etc. has been proposed (Patent Documents 1 and 2). must produce combined chlorine in For this reason, it is necessary to dissolve and mix it before adding it to the water to be treated, or to add a nitrogen-containing compound to the water to which hypochlorite, etc. has been added to generate combined chlorine, making the method of use complicated. There is a problem that there is

In addition, Patent Document 3 discloses a stable liquid preparation containing N-chlorosulfamic acid or N,N-dichlorosulfamic acid or a salt thereof produced from a chlorine-based oxidizing agent and sulfamic acid or a salt thereof. However, in order to stabilize the liquid formulation, it is necessary to make it strongly alkaline with a pH of 13 or more, which poses a problem of metal corrosion and a danger in handling.

Patent Document 4 indicates that a liquid preparation containing a chlorine-based oxidizing agent and sulfamoylbenzoic acid and its derivatives can be stabilized at pH 9.5 or higher, but the liquid preparation removes slime more effectively than chlorosulfamic acid. There were problems such as a low effect and an increase in TOC (total organic carbon).

JP-A-10-28981 Japanese Patent No. 5551120 Japanese Patent No. 3832399 Japanese Patent No. 4966936

An object of the present invention is to overcome the above problems, and more specifically, to provide a method for easily producing various combined chlorine compounds.

In view of the above situation, the present inventors have made intensive research and completed the method for producing the combined chlorine compound of the present invention, which is characterized by a chlorite, b primary and A liquid mixture containing one or more nitrogen-containing compounds selected from secondary amines, ammonia and ammonium salts and the above a and b is irradiated with ultraviolet rays.

The combined chlorine compounds referred to in the present invention may be of one type or plural types. The liquid mixture referred to here is an aqueous solution obtained by mixing the above a and b. All compositions of a and b are in principle water-soluble. The concentration as a whole is not particularly limited, but there is no problem if it dissolves. However, when the concentration is high, it affects the intensity of ultraviolet rays, which will be described later.

The point of the present invention lies in the irradiation of ultraviolet rays. This initiates and accelerates the reaction. First, the mechanism of generation of combined chlorine when a mixture containing chlorite and a nitrogen-containing compound is irradiated with ultraviolet rays will be described. When chlorite (eg, NaClO ₂ ) is irradiated with ultraviolet rays, the following photodecomposition reactions occur, resulting in hypochlorite ions (ClO ⁻ ), hypochlorous acid radicals (ClO), atomic oxygen (O), Atomic oxygen anion radicals (O ⁻ ) and chlorine dioxide (ClO ₂ ) are produced.
ClO ₂ ⁻ +hν→ClO ⁻ +O
ClO ₂ ⁻ +hν→ClO+O ⁻
ClO ₂ ⁻ +hν→(ClO ⁻ ) ^* ( ^* is an excited state)
(ClO ₂ ⁻ ) ^* +ClO ₂ ⁻ →ClO ₂ +ClO ⁻ +O ⁻

Hypochlorite ions produced by photolysis immediately react with amines and ammonia to produce combined chlorine.
ClO ⁻ +R—NH ₂ (primary amine)→R—NHCl
2ClO ⁻ +R-NHCl→R-NCl ₂
* Decomposition products such as hypochlorous acid radicals, atomic oxygen, and atomic oxygen anion radicals (O ⁻ ) generate chlorite ions, chlorine dioxide, and other byproducts through various reaction pathways. .

Further, Patent Document 3 also shows that combined chlorine is generated from a chlorine-based oxidant and sulfamic acid or a salt thereof, and one of the chlorine-based oxidants is chlorous acid or a salt thereof. there is However, it is known that the generation of combined chlorine generally proceeds in a chlorination reaction, and combined chlorine is not normally generated simply by coexisting chlorous acid or a salt thereof and sulfamic acid or a salt thereof. This is also clear from the results of experiments conducted by the inventors. Further, there is no mention of ultraviolet irradiation treatment as a constituent of the fungicidal and algicidal composition.

Furthermore, chlorous acid or its salts are known to undergo a disproportionation reaction under acidic conditions, which may generate a small amount of free chlorine, but the bactericidal and algicidal composition binds Since a pH of 13 or more is required to stabilize chlorine, free chlorine is considered to be substantially not generated.

Japanese Patent Publication No. 06-49562 discloses a method of generating chlorine dioxide by irradiating ultraviolet rays to a solution acidified by adding a buffering agent to chlorite. No mention is made of how chlorine is produced.

The chlorite of the present invention includes, for example, alkali metal chlorites and alkaline earth metal chlorites. Examples of alkali metal chlorites include sodium chlorite, potassium chlorite, and lithium chlorite. Examples of alkaline earth metal chlorites include calcium chlorite, magnesium chlorite, and sodium chlorite. Barium chlorate is mentioned. As the chlorite, alkali metal salts such as sodium salts and potassium salts are suitable from the viewpoints of water solubility and economy. These chlorites may be used singly or in combination of two or more.

In the present invention, primary and secondary amines are preferably, but not limited to, the following. Sulfamic acid, N-methylsulfamic acid, N,N-dimethylsulfamic acid, N-methylsulfamic acid, N-methylsulfamide, organic sulfonamides, taurine, N-methyltaurine, dimethyltaurine, N,N-dihydroxyethyl taurine, glycine, N-methylglycine, urea, alkanolamine, ethylenediamine, succinimide, cyanuric acid, alkylhydantoin, saccharin, benzenesulfonamide, p-toluenesulfonamide, melamine.

Ammonia is not particularly limited, and reagent, pharmaceutical, industrial, and food additive grades can be used as long as they are commercially available.

The ammonium salt is not particularly limited, but examples include inorganic acid ammonium salts such as ammonium phosphate, ammonium sulfate, ammonium nitrate, ammonium chloride and ammonium carbonate, and organic acid ammonium salts such as ammonium citrate, ammonium acetate and ammonium lactate. , ammonium tartrate and ammonium oxalate. Among these, ammonium salts of inorganic acids are preferred because they produce less by-products.

The mixing ratio of the chlorite and the nitrogen-containing compound is preferably 7 to 0.5, more preferably 5 to 1, in terms of chlorite ion (ClO ₂ ⁻ )/N molar ratio. If the (ClO ₂ ⁻ )/N molar ratio is out of this range, the amount of combined chlorine produced may be insufficient, or the amount of the nitrogen-containing compound may be excessive relative to the amount of combined chlorine produced.

The liquid mixture of the present invention preferably has a pH in the range of 6-13. This is because the stability of the liquid formulation is lowered and the handling risk is increased outside this range.

As the ultraviolet light source used in the present invention, conventionally known light sources can be used as long as they emit ultraviolet rays alone or include ultraviolet rays. Therefore, the wavelength of the light source is not limited to ultraviolet wavelengths (near ultraviolet rays of 200 to 380 nm, far ultraviolet rays of 10 to 200 nm, extreme ultraviolet rays of 1 to 10 nm). I do not care. As the ultraviolet light emitter, a mercury lamp and an LED lamp are preferable because they are inexpensive and easy to handle, but xenon lamps and deuterium lamps can also be used. It should be noted that the wavelength of the ultraviolet rays is preferably 100 to 365 nm from the viewpoint of efficiency in generating combined chlorine.

The irradiation intensity of the ultraviolet rays is preferably 1 mW/cm ² or more, more preferably 10 mW/cm ^{2 or} more, on the surface of the liquid mixture from the viewpoint of the combined chlorine generation rate. However, if it is too high, it is useless and may affect other things, so 1000 mW/cm ² or less is preferable.

The irradiation time of the ultraviolet rays to the liquid composition varies depending on the wavelength and intensity of the ultraviolet rays, so it cannot be set unconditionally. Long-term irradiation is not preferable because combined chlorine may be decomposed by ultraviolet rays. Therefore, it is preferable to set the ultraviolet irradiation time so that the chlorite ion residual rate is 5 to 50%, preferably 10 to 40%, of the initial concentration.

Components other than chlorite and nitrogen-containing compounds may be added to the mixture of the present invention (before UV irradiation) within a range that does not inhibit the stability of the composition or the generation of combined chlorine and the like. Other ingredients include bromine compounds, pH adjusters, buffers, surfactants, dispersants, chelating agents, corrosion inhibitors, perfumes, and the like.

The mixture of the present invention may be prepared in advance as a high-concentration aqueous solution and diluted appropriately at the time of use, or the powder containing chlorite and nitrogen-containing compound may be formed as it is or molded into tablets, etc., and dissolved in water at the time of use. You can let me.

In the present invention, chlorine dioxide produced by the photodecomposition reaction of chlorite may be contained in the finally obtained composition. This chlorine dioxide has excellent bactericidal and slime-removing effects and is low in toxicity. Therefore, when the combined chlorine compound produced by the method of the present invention is used in the water system to be treated, this chlorine dioxide is not removed and the mixture can be used as it is. Therefore, it is very convenient.

In addition, the chlorine dioxide may not be left as it is as described above, but may be sequentially taken out of the system. This is because chlorine dioxide is decomposed by the irradiated ultraviolet rays, and this is to be prevented or reduced. In order to increase the amount of chlorine dioxide produced, that is, to promote the reaction, the produced chlorine dioxide may be taken out of the system. Taking out of the system may be continuous or intermittent.
Methods for removing chlorine dioxide from the system include aeration, heating, ultrasonic waves, decompression degassing, gas separation membrane method, etc. Among them, aeration is preferred from the viewpoint of operability and economy. Gases for aeration are not particularly limited, but air, inert gases such as nitrogen gas, argon gas, and helium gas can be used.
That is, it is taken out of the liquid together with the chlorine dioxide-added gas generated in the solution. Aeration may be performed for the entire period of UV irradiation, but may be performed for a partial period or intermittently.

It is preferable to apply combined chlorine alone, that is, in an environment where chlorine dioxide gas is unnecessary, chlorine dioxide is removed from the system in advance in the same manner as above, or ultraviolet rays with a wavelength of around 365 nm are continuously irradiated to decompose and remove chlorine dioxide. You may

The combined chlorine compound obtained in the present invention is suitable for sterilization and cleaning of various water systems such as cooling towers, circulating baths, boilers, paper manufacturing processes, separation membranes, ballast water, swimming pools, etc., where microbial contamination and slime damage are a problem. can be used for

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the examples and comparative examples, the chlorite ion concentration, free chlorine concentration, combined chlorine concentration, and chlorine dioxide concentration were analyzed according to the following methods.

[Analysis of chlorite ion concentration]
Analysis was performed by ion chromatography (suppressor method). Analysis conditions are as follows.
Column: Shim-pack IC-SA3
Detector: electrical conductivity Eluent: 3.6 mM sodium carbonate aqueous solution Flow rate: 0.8 mL/min
Column temperature: 40°C

[Analysis of Free Chlorine, Combined Chlorine, and Chlorine Dioxide Concentration]
Concentration was measured by DPD (N,N-diethyl-p-phenylenediamine) absorptiometry using a simplified water quality meter AL-100 manufactured by AQUALYTIC. Each measurement procedure followed the following method.

[Measurement of free chlorine, combined chlorine and chlorine dioxide concentration]
10 mL of an appropriately diluted sample was collected, the DPD reagent was added, and after dissolution, the concentration was immediately measured in the residual chlorine measurement mode (A: free chlorine + chlorine dioxide). Next, the KI reagent was added, reacted for 2 minutes, and then the concentration was measured again (B: free chlorine + bound chlorine + chlorine dioxide).
・Measurement of chlorine dioxide concentration 10 mL of an appropriately diluted sample was taken, and 10 µL of 10% glycine aqueous solution was added. After adding the DPD reagent and dissolving, the concentration was immediately measured in the chlorine dioxide measurement mode (C: chlorine dioxide).
From the above measurement results, the concentration of each component was calculated by the following formula.
・Bound chlorine concentration = (B - A) x dilution ratio ・Free chlorine concentration = (A - C x 0.53 ^* ) x dilution ratio ・Chlorine dioxide concentration = C x dilution ratio *Chlorine dioxide between AL-100 measurement modes Ratio of concentration measurement values Residual chlorine measurement mode/Chlorine dioxide measurement mode = 0.53

<Test 1: Photoreaction characteristics of chlorous acid/nitrogen-containing compound>
Sodium chlorite and 5,5-dimethylhydantoin or ammonium chloride as a nitrogen-containing compound were added to pure water, and a phosphate buffer and sodium hydroxide were added to obtain an aqueous solution adjusted to a predetermined pH (Example 1-7). Similarly, aqueous solutions containing only sodium chlorite were prepared (Comparative Examples 1 to 4). Each sample was stored at room temperature for one day under light-shielding conditions, and then the concentration of each component was measured. Also, a 2.5 g sample was placed in a rectangular quartz cell (10 mm×10 mm×40 mm), irradiated with ultraviolet rays from the side of the cell, and the concentration was measured after a predetermined time had passed. A UV-LED was used as the ultraviolet light source, and the irradiation light wavelength and intensity (liquid level) were λ265 nm (15 mW/cm ² ), λ300 nm (25 mW/cm ² ), and λ365 nm (140 mW/cm ² ).

The components of Examples and Comparative Examples are shown in Tables 1 and 2, and the results are shown in Tables 3 and 4.

In the compositions containing sodium chlorite and nitrogen-containing compounds of Examples 1 to 7, combined chlorine, free chlorine, and chlorine dioxide were not detected before UV irradiation, but after UV irradiation, combined chlorine and dioxide were detected. A significant increase in the chlorine concentration was observed, and in Examples 1 and 2, a small amount of free chlorine was also produced. On the other hand, in Comparative Examples 1 to 4, the products after ultraviolet irradiation were only chlorine dioxide and free chlorine. From the above results, it was confirmed that various types of combined chlorine can be produced in the present invention by changing the nitrogen-containing compound in the liquid composition.

test 2
<Combination effect of aeration>
20 g of the composition of Example 1 was placed in a quartz bottle equipped with an aeration glass filter, and a Teflon (registered trademark) tube was used to connect three glass bottles containing 100 mL of pure water (for recovering chlorine dioxide) in series. The composition was irradiated with ultraviolet rays while air was supplied at a rate of 0.3 L/min. Table 5 shows the results. From this, it can be seen that the amount of chlorine dioxide produced increases when aeration is performed.

It was confirmed that when the aeration of Example 3 was added, the amount of chlorine dioxide generated was increased by about 10 times compared to when there was no aeration.

test 3
<Storage stability of liquid composition>
Pure water was blended with 25% sodium chlorite, 5,5-dimethylhydantoin and sodium hydroxide to obtain a composition with a pH of 9.5 (Example 9). Also, pure water was mixed with 12% sodium hypochlorite, 5,5-dimethylhydantoin and sodium hydroxide to obtain a composition containing combined chlorine (Comparative Example 5). After aging each aqueous solution at 50° C. for 7 days, the active ingredient concentration was measured.
The chlorite ion and available chlorine concentrations were measured by iodometric titration, and the 5,5-dimethylhydantoin concentration (DMH) was measured by absorbance (λ212 nm) with an ultraviolet-visible spectrophotometer.

Table 6 shows the results.

In the composition containing sodium chlorite and 5,5-dimethylhydantoin of Example 9, the concentration of chlorite ions and dimethylhydantoin decreased slightly after aging at 50°C for 7 days. On the other hand, in the composition containing combined chlorine of Comparative Example 5, no available chlorine was detected after the passage of time.

Claims (5)

a chlorite,
b one or more nitrogen-containing compounds selected from 5,5-dimethylhydantoin, sulfamic acid, ammonium chloride,
A method for producing combined chlorine, which comprises irradiating a liquid mixture containing the above a and b with ultraviolet rays. 2. The method for generating combined chlorine according to claim 1, wherein the intensity of said ultraviolet rays is 1 mW/cm ^<2> or more on the surface of said liquid mixture. 3. The method for producing combined chlorine according to claim 1, wherein the ultraviolet wavelength is 100 nm to 365 nm. The method for producing combined chlorine according to any one of claims 1 to 3, wherein the liquid mixture has a pH of 6 to 13. 5. The method for producing combined chlorine according to any one of claims 1 to 4, further comprising a step of aerating the liquid mixture during irradiation with the ultraviolet rays and continuously extracting the produced chlorine dioxide to the outside.