TW201902563A - Cleaning fluid, detergent, and cleaning method for water-contact member - Google Patents

Abstract

A cleaning fluid and detergent for water-contact members which both contain free chlorine and a combined-chlorine compound, wherein the molar ratio of the total chlorine (Cl2) to the nitrogen atoms N derived from the combined-chlorine compound, Cl2/N, is 1 or higher, the cleaning fluid having a pH of 9 or higher and the detergent having a pH of 12 or higher. The cleaning fluid can be prepared by diluting the detergent with water. Also provided is a cleaning method for water-contact members which comprises using the cleaning fluid to clean a water-contact member.

Description

Washing liquid for water receiving member, detergent and washing method

The present invention relates to a cleaning liquid, a detergent, and a cleaning method for cleaning a water receiving member such as a UF film (ultrafiltration membrane), an MF membrane (precision filtration membrane), a filter, a pipe, a pressure gauge, and a flow meter.

In the membrane separation device (the membrane removal device) using the UF membrane or the MF membrane, since the separation membrane adheres to the scale, the cleaning fluid (water and/or gas) is intermittently supplied for every 30 seconds to 60 minutes. Physically washed.

However, even after the physical cleaning, there is still unremovable dirt accumulated on the membrane, and the filtration capacity of the membrane is gradually reduced.

Therefore, it is necessary to use the medicines regularly or irregularly to clean the turbid film device.

Patent Document 1 describes that a film which is easily oxidized and deteriorated is washed by a chlorine-binding agent. Further, Patent Document 1 discloses that the concentration of the chloramine compound in the detergent to be added is 0.005 to 0.5 M, and the molar ratio (Cl ₂ /N) of the available chlorine (Cl _{2 )} to the nitrogen atom N derived from the chloramine compound is 0.1 to 1. Therefore, in the cleaning method of Patent Document 1, the film is washed under the condition that there is almost no free chlorine.

Patent Document 2 describes the sterilization of a cooling water system, a drainage water system, and a pulp water system using a combined chlorine agent having a Cl ₂ /N ratio of 1. Patent Document 2 also discloses that the concentration of free chlorine in the sterilization treatment is 0.05 mg/L or more. Patent Document 2 does not describe the use of a detergent for selectively permeable membranes.

[Patent Document 1] JP-A-2009-195913 (Patent Document 2) JP-A-2009-195823

An object of the present invention is to provide a cleaning liquid, a detergent, and a cleaning method which have a high cleaning effect.

The gist of the present invention is as follows.

In the cleaning liquid for the water-receiving member of the present invention, the molar ratio (Cl ₂ /N) of the total chlorine to the nitrogen atom N derived from the chloramine compound is 1 or more in the cleaning liquid containing the free chlorine and the chloramine compound. The pH is 9 or more.

In one aspect of the cleaning solution of the present invention, the chloramine compound is at least one sulfanilic acid compound selected from the group consisting of a combined chlorosulfonic acid and a salt thereof.

In one aspect of the cleaning solution of the present invention, the water receiving member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.

In the aspect of the washing liquid of the present invention, the pH of the washing liquid is 11 or more.

In the washing liquid of the present invention, the chlorine concentration of the chloramine compound and chlorine is 100 mg/L or more, and the free chlorine concentration is 20 mg/L or more.

The detergent for the water-receiving member of the present invention is a detergent containing free chlorine and a chloramine compound, wherein the molar ratio (Cl ₂ /N) of the total chlorine to the nitrogen atom N derived from the chloramine compound is 1 or more. The pH is 12 or more.

In one aspect of the detergent of the present invention, the chloramine compound is at least one sulfanilic acid compound selected from the group consisting of a combined chlorine sulfamic acid and a salt thereof.

In one aspect of the detergent of the present invention, it is obtained by mixing a sulfamic acid with an alkali agent and then adding a chlorine agent to form a bound chlorine compound.

In one aspect of the detergent of the present invention, the concentration of the sulfaic acid relative to the weight of the final detergent is 5% by mass or less.

In one aspect of the detergent according to the present invention, the water receiving member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.

The washing liquid of the water receiving member of the present invention is obtained by diluting the above-described detergent of the present invention with water.

In the method of cleaning the water receiving member of the present invention, the water receiving member is washed using the cleaning liquid of the present invention. [Effects of the Invention]

The washing liquid, the detergent and the washing method of the water-receiving member of the present invention have the strong oxidizing power of the free chlorine agent and the strong osmosis force of the combined chlorine agent (chloramine compound) with respect to the inside of the water-receiving member. . Therefore, it is more effective when compared with the chlorine agent, and has a higher washing effect when compared with the free chlorine agent. Further, the cleaning liquid and the detergent of the present invention also have an excellent bactericidal effect.

The embodiment of the present invention will be described in detail below.

The present invention relates to a cleaning liquid, a detergent, and a washing method. However, in the present invention, the "washing liquid" and the "cleaning agent" are the following differences. The washing liquid of the present invention means a liquid used for washing. Further, the detergent of the present invention means a product used at the time of circulation. In some cases, the detergent may be directly used as a washing liquid to be washed. However, the detergent is usually diluted with water or the like and used as a washing liquid for washing.

The cleaning solution of the present invention contains free chlorine and a combined chlorine compound. In the cleaning liquid of the present invention, the molar ratio (Cl ₂ /N) of the perchlorine (Cl ₂ ) to the nitrogen atom N derived from the combined chlorine compound is 1 or more, and the pH is 9 or more.

Cleaning solution of the present invention is preferably, all the chlorine concentration of 5,000mg-Cl ₂ / L or less, more preferably _{200 ~ 5,000mg-Cl 2 / L} , particularly preferably _{1,000 ~ 2,000mg-Cl 2 / L} , combined chlorine The concentration is 100 mg-Cl ₂ /L or more, more preferably 100 to 4,980 mg-Cl ₂ /L, particularly preferably 300 to 1,980 mg-Cl ₂ /L, and the free chlorine concentration is 20 mg-Cl ₂ /L or more, more preferably 20 to 4,900 mg-Cl ₂ /L, particularly preferably 20 to 1,700 mg-Cl ₂ /L.

In the detergent containing the free chlorine and the chloramine compound, the molar ratio (Cl ₂ /N) of the total chlorine (Cl ₂ ) to the nitrogen atom N derived from the chloramine compound is 1 or more. The pH is 12 or more.

In the detergent of the present invention, the total chlorine concentration (concentration in terms of Cl ₂ ) is preferably 10% by mass or less, more preferably 1 to 8% by mass, particularly preferably 3 to 8% by mass. The combined chlorine concentration (concentration in terms of Cl ₂ ) is 0.1% by mass or more, more preferably 0.5 to 3% by mass, particularly preferably 1 to 2.8% by mass, and the free chlorine concentration (concentration in terms of Cl ₂ ) is 0.02% by mass or more, more preferably It is 0.1 to 10% by mass, particularly preferably 1 to 5% by mass.

The total chlorine concentration and the free chlorine concentration in the present invention are measured by the DPD method prescribed in JIS K 0400-33-10:1999. Further, the combined chlorine concentration is obtained by subtracting the free chlorine concentration from the above-mentioned total chlorine concentration.

In the present invention, a chlorine-based cleaning solution and a detergent can be applied to a water-receiving member under alkali conditions. In the present invention, in addition to the exfoliation and hydrolysis of the organic substance obtained by the washing under the alkali condition, the decomposition of the organic substance by the combined chlorine compound and the effect of the sterilization by the free chlorine can be multiplied. . Therefore, according to the present invention, the alkali washing effect can be improved, and the performance of the contaminated selectively permeable membrane and the filter can be sufficiently recovered.

<Water-receiving member> The water-receiving member is, for example, a UF film, an MF film, a filter, a pipe, a pressure gauge, a flow meter, or the like, but is not limited thereto. For the filter, for example, a granular filter material such as sand or anthracite is used. In the present invention, when the MF film and the UF film are used for cleaning, the cleaning effect can be effectively exhibited. However, the selective permeable membrane is not limited thereto, and the present invention is also applicable to other selectively permeable membranes, and the membrane material is not limited. Further, the form of the film and the like are not limited, and the present invention can be effectively applied to a selective permeable membrane for water treatment in a wide range of washing applications.

<Free chlorine> The free chlorine system uses hypochlorous acid and/or hypochlorite. As the hypochlorite, an alkali metal salt of hypochlorous acid such as sodium hypochlorite or an alkaline earth metal salt of hypochlorous acid such as calcium hypochlorite can be used. These may be used alone or in combination of two or more.

<Bound Chloride Compound> The bound chlorine compound is preferably an amine obtained by reacting hypochlorous acid (HOCl) with a compound having a primary amine group (XNH ₂ ) as shown in the following reaction formulas (1) and (2). A compound (XNHCl) in which a hydrogen atom is replaced by a chlorine atom. Since this compound is weak in oxidation, the aromatic polyamine-based RO membrane having low chlorine resistance can also be used as a cleaning liquid and a detergent, and even if it has a higher viscosity than a polysaccharide. The substance can also be impregnated and exert a decomposition inside.

In the present invention, it is preferred to incorporate a chlorine compound by mixing any one of a compound having a primary amine group, ammonia, and an ammonium salt (hereinafter referred to as "NH ₂ -based compound"), and hypochlorous acid and/or Produced by chlorate. A compound having a primary amine group such as an aliphatic amine, an aromatic amine, a sulfanilic acid, a p-aminobenzenesulfonic acid, an amidoxime benzoic acid, an amino acid or the like. Further, the ammonium salt is, for example, ammonium chloride or ammonium sulfate. These may be used alone or in combination of two or more. Among these NH ₂ -based compounds, sulfamic acid (NH ₂ SO ₂ OH) is preferred. When a sulfanilic acid is used to form monochlorosulfonamide, a stable combined chlorine compound can be obtained. Sulfamic acid does not increase the TOC value of the detergent because it does not contain carbon. A very effective cleaning solution and detergent can be obtained by using sulfamic acid and an alkali agent.

As the hypochlorite to be reacted with the NH ₂ -based compound, an alkali metal salt of hypochlorous acid such as sodium hypochlorite or an alkaline earth metal salt of hypochlorous acid such as calcium hypochlorite can be used. These may be used alone or in combination of two or more. When a sulfamic acid is used as the compound having a nitrogen atom in combination with chlorine, the weight concentration of the sulfamic acid used is preferably 5% by mass or less based on the weight of the final detergent. When the concentration of sulfamic acid is more than 5% by mass, chlorine is easily decomposed.

<Ratio of free chlorine and bound chlorine compound> In the present invention, the molar ratio (Cl ₂ /N molar ratio) of the available chlorine (Cl ₂ ) derived from free chlorine to the nitrogen atom N derived from the bound chlorine compound is 1 or more. Good for 1 to 10, especially for 1 to 5. By this range, a good balance between the immediate cleaning effect of free chlorine and the permeation cleaning action of the combined chlorine compound can be obtained.

<pH> The washing liquid of the present invention is formed of an aqueous alkali solution containing free chlorine and a chlorine-binding compound, and has a pH of 9 or more. When the pH of the washing liquid is less than 9, the sufficient detergency cannot be obtained. When the pH of the washing liquid is high, the washing effect is excellent. However, when it is too high, it is less rational to use as a cleaning liquid, which will deteriorate the washed film and increase the risk of corrosion of the metal. The pH of the washing liquid is preferably 11 or more and 13 or less.

The pH of the cleaning liquid of the present invention is preferably 9 or more, and particularly preferably 12 or more. The alkali agent used is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.

The detergent of the present invention is formed from an aqueous solution containing free chlorine and a combined chlorine, and has a pH of 12 or more. When the pH of the detergent is less than 12, the storage stability is poor, and the cleaning effect during dilution may be insufficient. The pH of the detergent is preferably 13 or more. When the pH of the detergent is too high, the total chlorine concentration is lowered, and the balance with the pH at the time of dilution is deteriorated. The pH limit of the detergent of the present invention is 14.

<Method for Producing Cleaning Liquid and Detergent> The cleaning solution and the cleaning agent of the present invention can be obtained by adding an NH ₂ -based compound such as sulfamic acid to an aqueous solution of the alkaline agent, and dissolving hypochlorous acid and / or hypochlorite is added to the obtained aqueous solution of the NH ₂ -based compound to prepare an aqueous solution of the combined chlorine compound, and then hypochlorous acid and/or hypochlorite is added to the aqueous solution of the combined chlorine compound to obtain a mixture.

A compound having a primary amine group such as sulfamic acid may be added in the form of a salt. As the salt, sodium sulfamate, potassium sulfamate, ammonium sulfamate or the like can be used.

The cleaning solution of the present invention can be obtained by, if necessary, diluting the above-mentioned detergent prepared with water, preferably pure water.

<Other components> The cleaning liquid and the detergent used in the present invention may be added with other detergent components within a range in which the cleaning effect is not impaired.

For example, in order to improve the peeling effect of the membrane fouling substance, one or more surfactants may be added, or EDTA (ethylene diamine tetraacetic acid), EGTA (ethylene glycol bis(aminoethyl ether) tetraacetic acid), Another detergent component such as a chelating agent such as IDA (iminodiacetic acid).

<Washing method> In the method of washing the water receiving member using the washing liquid of the present invention, the water receiving member is brought into contact with the washing liquid. When the water receiving member is an MF membrane or a UF membrane, the cleaning liquid is introduced into the membrane device after the membrane device is passed through the water. The washing liquid may be introduced from the raw water supply port of the membrane device, or introduced from the treated water outlet side and then pressed to the raw water side. After introducing the cleaning liquid into the apparatus, the membrane is immersed in the cleaning liquid or the washing liquid is circulated. When circulating the cleaning solution, air can be blown into the cleaning solution. Including immersion and circulation, the time during which the cleaning solution contacts the selectively permeable membrane is preferably from 1 to 24 hours, particularly preferably from 1 to 18 hours. The time during which the washing liquid contacts the water receiving member in the water-receiving member other than the film is also preferably from 1 to 24 hours, particularly preferably from 1 to 18 hours. [Examples]

[Comparative Examples 1 to 4, Example 1] A film (effective film length: 100 mm) obtained by using a UF hollow membrane module (HFU-2008, membrane material PVDF, pore size: 0.01 μm) manufactured by Toray Co., Ltd. was used to prepare a film. Component (single component). Then, the industrial water used in the original area of the Fukui City, Chiba Prefecture (hereinafter referred to as Yamakura Kogyo) was passed through the water-passing device in the single-component assembly shown in Fig. 1 to contaminate the membrane.

The film 1 is disposed in the column 2 held by the holding members 3a and 3b formed of the potting material at the upper and lower ends. The upper end of the membrane 1 is embedded in the holding member 3a, and the lower end of the membrane 1 passes through the holding member 3b to communicate with the chamber 4 below the tubular string 2. The pipe 5, the pump 6 and the valve 7 supply the Yamakura water below the pipe string 2 (on the upper side of the holding member 3b), and the permeated water system flows out from the chamber 4 at the lower end of the pipe string 2 through the valve 8 and the pipe 9. . The concentrated water is discharged from the upper side of the column 2 (directly below the holding member 3a) through the pipe 10 and the valve 11. The backwash water is introduced into the chamber 4 at the lower end of the column 2 through the pipe 12, the pump 13, and the valve 14, and flows into the film 2. The countercurrent drainage system flows out from the pipe 10 through the branch pipe 15 and the valve 16.

The water-passing system was carried out in the following four steps for the membrane fouling, and was repeated for 200 cycles. Step 1: Filling water (30 seconds) Step 2: Filtration (permeate flow rate 2 to 4 m ³ /m ² /d, 28 minutes) Step 3: Backwash (water volume 0.6 to 1.4 mL/min, 30 seconds) Step 4: Drainage (30 seconds

When the pure water was passed through the film after the contamination, the inter-membrane differential pressure of the permeation flow rate of 4 m ³ /m ² /d was measured as the inter-membrane differential pressure value before washing. Thereafter, the cleaning liquid shown in Table 1 was introduced into the column 2 to perform immersion. After immersing for a certain period of time, the syrup was discharged, and after washing with pure water, the pure water was passed through and the inter-membrane differential pressure of the permeation flow rate of 4 m ³ /m ² /d was measured to obtain the inter-membrane differential pressure value for the predetermined period of time. After the differential pressure between the membranes was measured, the chemical solution was introduced again, and the operation was repeated until the total immersion time was 6 to 8 hours. Moreover, the liquid medicine introduced each time is re-modulated. The measurement result of the differential pressure value between the membranes (the relationship between the immersion time and the differential pressure value between the membranes) is shown in Fig. 2 . Further, any of the washing liquids has a pH of 12 and a total chlorine concentration of about 1200 mg. The free chlorine concentration was determined by the DPD method.

[Investigation] When the washing was carried out by the sodium hypochlorite of Comparative Example 1, the differential pressure immediately after washing (highly effective) was significantly lowered, but the final differential pressure was higher than that of Comparative Examples 2 to 4, so The cleaning effect is worse than the combined chlorine agent. When the cleaning was carried out by the combined chlorine agents of Comparative Examples 2 to 4, the differential pressure was finally lowered at the time of washing, and the washing effect was high, but the cleaning effect was inferior to that of the sodium hypochlorite of Comparative Example 1. When it is washed by the washing liquid of Example 1 (in combination with chlorine + free chlorine agent), it has the same effect as that of sodium hypochlorite, and has the same washing effect as the chemical and chlorine agent.

[Comparative Example 5, Examples 2 to 4] Film washing was carried out under the same conditions as in Comparative Examples 1 to 4 and Example 1 except that the cleaning liquid was as shown in Table 2. (However, the experimental day is different from Comparative Examples 1 to 4 and Example 1, so the water quality of the raw water is somewhat different, and the membrane contamination status is also somewhat different). Further, any of the cleaning solutions has a pH of 12 and a total chlorine concentration of about 1200 mg-Cl ₂ /L. The result is shown in Figure 3.

[Investigation] Examples 2 to 4 have the same effect as the sodium hypochlorite of Comparative Example 5, and have a film-to-membrane differential pressure (higher washing effect) lower than that of sodium hypochlorite in the final arrival differential pressure.

[Comparative Examples 6 to 8, Example 5] After the detergent shown in Table 3 was diluted to a total chlorine concentration of 1000 mg-Cl ₂ /L, a washing liquid having a pH adjusted to 12 by NaOH was prepared. Further, the immersion time in the chemical liquid washing step was set to 400 min. Except for this, the same experiment as the above Comparative Examples and Examples was carried out. However, the experimental day is different from the above comparative examples and examples, so the water quality of the raw water is somewhat different, and the pollution state of the membrane is also somewhat different.

Figure 4 shows the relationship between the cleaning time and the differential pressure. From this, it was found that the cleaning solution prepared by diluting the detergent of Example 5 can reduce the differential pressure most rapidly and reach a lower differential pressure. The arrival differential pressure of Comparative Example 6 was still high, and the arrival differential pressure of Comparative Example 7 and Comparative Example 8 was similar to that of Example 5, but the differential pressure reduction rate was slow.

<Experimental Examples 1 to 3> Next, the bactericidal effect of the aqueous solution was evaluated. After diluting the following agents to a certain concentration of available chlorine, the exposed bacteria were exposed for 15 minutes or 1 hour, and the number of bacteria was measured. The evaluation strain used was Aspergillus niger. Experimental Example 1: Sodium hypochlorite aqueous solution (effective chlorine 12%) Experimental Example 2: Sulfamic acid-based combined chlorine agent Cl ₂ /N ratio = 0.56 Aqueous solution of pH 14.0 Experimental Example 3: Sulfamic acid-based free chlorine, combined with chlorine agent Cl ₂ / N ratio = 2.08 aqueous solution of pH 14.1

The result of 15 min is shown in Figure 5. The result of 1h is shown in Fig. 6. From this, it was confirmed that the effective chlorine concentration of 10 m/L was completely sterilized at 15 minutes with respect to the experimental examples 1 and 3. In the experimental example 2, the effective chlorine was 200 mg/L, and even after 1 hour, almost the bacteria survived. In Experimental Example 1, although the bactericidal effect was high, the drug was the same as that of Comparative Example 6, and the washing effect was poor. From the above, it is known that the detergent sterilizing agent of the present invention has a high washing effect and a sterilizing effect.

[Experimental Test of Chlorine Decomposition Rate] A detergent was added as shown in Table 4 using sulfanilic acid, sodium hypochlorite aqueous solution (effective chlorine 12% by mass), 48% sodium hydroxide, and pure water. The weight concentration of the sulfamic acid is 2.5 to 5.0% by mass. The relationship between the concentration of sulfamate molars of the detergent obtained by adding (i) to (iv) and the residual effective chloromol concentration, and the decomposition rate of chlorine are shown in Fig. 7. As shown in Fig. 7, the higher the weight concentration of sulfamic acid, the greater the decomposition rate of chlorine. When the weight concentration of sulfamic acid is 5.0% by mass, the ratio of (effective chloromol concentration) / (sulfuric acid molar concentration) is only more than 1 to 1.01. Therefore, the weight concentration of the sulfamic acid is preferably 5.0% by mass or less. The reason why the decomposition rate of chlorine is large is presumed to be that it is easy to generate unstable dichlorosulfonamide.

The present invention has been described in detail with reference to the specific embodiments thereof. The present application is based on Japanese Patent Application No. 2017-050165, filed on Jan.

1‧‧‧Selective permeable membrane

2‧‧‧ column

Fig. 1 is a schematic view showing the structure of a test apparatus used in the embodiment. Fig. 2 is a graph showing the results of Examples and Comparative Examples. Fig. 3 is a graph showing the results of Examples and Comparative Examples. Fig. 4 is a graph showing the results of Examples and Comparative Examples. Fig. 5 is a graph showing the results of Examples and Comparative Examples. Fig. 6 is a graph showing experimental results. Fig. 7 is a graph showing experimental results.

Claims (12)

A cleaning solution for a water-receiving member, which is a cleaning solution containing free chlorine and a chloramine compound, wherein a molar ratio (Cl ₂ /N) of total chlorine to a nitrogen atom N derived from a chloramine compound is 1 or more, pH It is 9 or more. The cleaning solution according to claim 1, wherein the chloramine compound is a sulfamic acid-based compound containing at least one selected from the group consisting of a chlorosulfic acid and a salt thereof. The cleaning solution according to claim 1 or 2, wherein the water receiving member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter. The cleaning solution according to any one of claims 1 to 3, wherein the pH is 11 or more. A cleaning liquid characterized in that, in any one of claims 1 to 4, the chlorine concentration of the chloramine compound and chlorine is 100 mg/L or more, and the free chlorine concentration is 20 mg/L or more. A detergent for a water-receiving member, which is a detergent containing free chlorine and a chloramine compound, wherein a molar ratio (Cl ₂ /N) of total chlorine to a nitrogen atom N derived from a chloramine compound is 1 or more, pH It is 12 or more. The detergent according to claim 6, wherein the chloramine compound is a sulfamic acid-based compound containing at least one selected from the group consisting of a chlorosulfic acid and a salt thereof. A detergent according to claim 6 or 7, which is obtained by mixing a sulfamic acid with an alkali agent and then adding a chlorine agent to form a bound chlorine compound. The detergent according to claim 7 or 8, wherein the concentration of the sulfamic acid is 5% by mass or less based on the weight of the final detergent. The detergent according to any one of claims 6 to 9, wherein the water receiving member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter. A cleaning solution for a water-receiving member obtained by diluting the detergent according to any one of claims 6 to 9 with water. A cleaning method for a water receiving member, which is to wash the water receiving member using the cleaning liquid according to any one of claims 1 to 5 and claim 11.