JP5507038B2 - Disinfectant for reverse osmosis membrane and reverse osmosis membrane sterilization method using the same - Google Patents

Description

  The present invention relates to a sterilization treatment technique for a reverse osmosis membrane (hereinafter also referred to as RO membrane) in a pure water and ultrapure water production process or the like.

  In pure water and ultrapure water production processes, RO membranes that can remove fine particles, ions, and the like are frequently used. Generally, RO membranes include cellulose acetate membranes (CA membranes) and polyamide membranes (PA membranes). However, in recent years, CA membranes are gradually not used from the viewpoint of operating pressure, equipment and operating costs.

  On the other hand, the use of PA membranes has been increasing in recent years because the operating pressure can be reduced compared to CA membranes. However, since the membrane material is attacked by an oxidizing disinfectant such as hypochlorous acid, these sterilizations are performed. There is a problem that the use of the agent is not preferable.

  In RO membrane devices in the production process of pure water and ultrapure water, performance degradation such as reduction in permeate volume, deterioration in treated water quality, increase in water flow differential pressure, etc. due to microorganism-derived slime accompanying the growth of microorganisms in the system Is caused. Various bactericides have been proposed to prevent these microbial contaminations. In general, there are the above-mentioned oxidizing fungicide (hypochlorous acid), organic nitrogen fungicide, halocyanoacetamide fungicide and the like.

  However, in the case of a PA film, since the film material is affected by the oxidizing disinfectant as described above, the use is not preferable. Also, treatment with an organic nitrogen-based disinfectant has been proposed (for example, Patent Document 1), but there remains a problem that sufficient effects cannot be obtained unless the target water is added at a high concentration.

  On the other hand, halocyanoacetamide-based bactericides do not invade membrane materials and have a high bactericidal effect, so use as RO membrane bactericides has been proposed (for example, Patent Document 2). However, since a halocyanoacetamide compound is generally difficult to dissolve in water, it is necessary to add the solid directly to the water to be treated, or dissolve it in water or other solvent in advance to prepare it in liquid form before use.

  When solids are added directly to the water to be treated, the handling risk increases. In general, the amount of addition to a predetermined concentration is extremely small, and a device such as a dissolver is necessary. In addition, when preparing a liquid disinfectant, halocyanoacetamide compounds have low solubility in water and poor chemical stability in water, so that they can be used in hydrophilic alcoholic or glycolic organic solvents or mixtures thereof. It is generally known to use after dissolving. As an organic solvent for dissolving the halocyanoacetamide compound, ethylene glycol and the like are disclosed (for example, Patent Document 3).

However, since a part (5% or more) of a substance having a low molecular weight such as ethylene glycol permeates the RO membrane, there is a problem that the quality of the treated water is deteriorated. In addition, when a solvent having a large molecular weight is used, the permeability of the RO membrane can be reduced, but the viscosity of the liquid disinfectant increases, and it is difficult to dissolve in the preparation when it is difficult to flow in a device such as a chemical injection pump. There is.
JP-A-8-229363 JP 2006-89402 A JP-A-61-44804

  Therefore, in view of the above circumstances, an object of the present invention is to disinfect a composition having a fungicidal composition, such as a halocyanoacetamide compound, which does not attack a film material and has a high bactericidal effect but is generally hardly soluble in water. An object of the present invention is to provide an RO membrane treatment agent that does not deteriorate the quality of treated water and the RO membrane treatment method using the same, although the method of use and the production method are not complicated.

  In view of the above problems, the present inventors have conducted intensive research. As a result, the alcohol or glycol organic solvent containing the following structure 1 or structure 2 is compared with a linear alcohol or glycol organic solvent having the same molecular weight. The RO membrane permeability was found to be extremely low. This is presumably because the bulkiness of the molecules is increased by the branched structure such as Structure 1 or Structure 2 below, and it is difficult to permeate the RO membrane. The present invention has been completed by utilizing the characteristics of the alcohol or glycol-based organic solvent containing such structure 1 or structure 2.

That is, the bactericidal agent for reverse osmosis membrane according to the present invention is a halocyanoacetamide compound represented by the general formula 1 of Chemical Formula 3 (wherein X is the same or different halogen atom or hydrogen atom, R 1 contains the a disinfectant consisting of only hydrogen atom or an alkyl group having 1 to 3 carbon atoms), tert-butanol, and at least one organic solvent of the dipropylene glycol and tripropylene glycol, the pure water and It consists of what is water-flowing through the reverse osmosis membrane in an ultrapure water manufacturing process . That is, it is a fungicide for reverse osmosis membranes containing an alcohol or glycol organic solvent having a specific structure and a fungicide made of a specific compound.

In such a fungicide for reverse osmosis membrane according to the present invention, it is particularly preferable that the molecular weight of the alcohol or glycol organic solvent is in the range of 70 to 200. By setting the molecular weight within this range, it becomes an organic solvent that is particularly difficult to permeate the RO membrane and is not complicated to use and manufacture, and the intended purpose can be achieved more reliably.

The present invention also provides a reverse osmosis membrane sterilization method characterized by treating a reverse osmosis membrane composed of a polyamide-based composite membrane with the above-described anti-osmosis membrane sterilizing agent. That is, using a disinfectant for reverse osmosis membrane according to the present invention, it is to sterilize the reverse osmosis membrane comprising a polyamide-based composite membrane is the mainstream in recent years use.

  According to the present invention, while using a halocyanoacetamide compound, a compound that does not attack the membrane material and has a high bactericidal effect but is generally hardly soluble in water, Since it is used by dissolving in an alcohol or glycol-based organic solvent containing the structure 1 or structure 2 of Chemical Formula 1 or Chemical Formula 2, it has a predetermined concentration in the water to be treated easily while taking advantage of its excellent characteristics as a disinfectant composition. Can be added. And since the organic solvent contained has the above-mentioned specific structure, it is difficult to permeate the RO membrane. As a result, compared with the case of using a conventional linear organic solvent, the quality of treated water Can be significantly reduced.

Hereinafter, the present invention will be described in detail together with preferred embodiments.
In the present invention, a specific compound, typically a halocyanoacetamide compound, is used as the RO membrane sterilizing agent. This halocyanoacetamide compound is represented by the aforementioned general formula 1. Specific examples of such halocyanoacetamide compounds include 2-bromo-3-nitrilopropionamide, 2,2-dibromo-3-nitrilopropionamide (DBNPA), 2-chloro-2-bromo-3-nitrilopropion Amides, 2-chloro-3-nitrilopropionamide 2,2-dichloro-3-nitrilopropionamide, N-methyl-2,2-dibromo-3-nitrilopropionamide, N-propyl-2-chloro-2-bromo -3-nitrilopropionamide and the like. These may be used alone or in combination of two or more.

  The content of the halocyanoacetamide compound represented by the above general formula 1 is preferably 1 to 60% by mass, more preferably 10 to 40% by mass in the RO membrane fungicide. Here, when the content is less than 1% by mass, it is necessary to increase the amount of the agent added to the water to be treated, which increases transportation costs and is not economical. When the content exceeds 60% by mass, quality degradation such as precipitation of a halocyanoacetamide compound may occur, which is not preferable.

The organic solvent in the present invention is an alcohol or glycol solvent containing the structure 1 or structure 2 of the chemical formula 1 or chemical formula 2. Such alcohol or glycol solvent, specifically, t Ert- butanol, dipropylene glycol, tripropylene glycol. These may be used alone or in combination of two or more.

Moreover, in this invention, you may add water , an acid, an alkali, a well-known scale inhibitor, a chelating agent, and an anticorrosive as needed.

  Examples of the scale inhibitor include polyacrylic acid, acrylic acid / hydroxyethylidene methacrylate copolymer, acrylic acid / hydroxyethylidene methacrylate / methyl acrylate copolymer, and acrylic acid / allyl glycidyl ether copolymer. Polymer, acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid copolymer, acrylic acid / isoprenesulfonic acid copolymer, acrylic acid / vinylsulfonic acid, acrylic acid / allylsulfonic acid copolymer Polymer, maleic acid or maleic anhydride / isobutylene copolymer, maleic acid or maleic anhydride / styrene sulfonic acid copolymer, maleic acid or maleic anhydride / acrylic acid copolymer, maleic acid or maleic anhydride Acid / acrylate acid copolymer, maleic acid or maleic anhydride A copolymer of phosphate / 2-acrylamido-2-methylpropanesulfonic acid, a copolymer of maleic acid or maleic anhydride / amylene acid, polyacrylamide, can be mentioned polyitaconic acid and their salts and the like. Examples of the chelating agent include EDTA (ethylenediamine tetraacetic acid), TET (triethylenetetraamine), and EGTA (ethylene glycol bistetraacetic acid). Further, as the anticorrosive, for example, tolyltriazole, benzotriazole, methylbenzotriazole, molybdic acid, tungstic acid, silicic acid, nitrous acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphonic acid , Hexametaphosphoric acid, tripolyphosphoric acid, orthophosphoric acid and salts thereof, zinc chloride, acidic zinc chloride hydrochloride, zinc sulfate, zinc lignin sulfonate, hydrazine and the like.

  In addition, the content of the alcohol or glycol solvent as described above is preferably 0.1 to 50 times, more preferably 0.5 to 5 times by weight with respect to the halocyanoacetamide compound. In particular, the molecular weight of these alcohol or glycol solvents is preferably in the range of 70 to 200. If the molecular weight is less than 70, it is not preferable because it easily permeates the RO membrane and deteriorates the quality of treated water. On the other hand, if the molecular weight exceeds 200, the viscosity becomes high, which causes problems such as difficulty in flowing the drug through a device such as a pump.

  Hereinafter, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited by these.

Example 1
(RO membrane permeability)
Example 1 and Comparative Examples 1, 2, and 3 having a composition as shown in Table 1 (bactericide composition (% by weight)) were prepared. These were added to ultrapure water at 100 mg / L, respectively, and the water was passed through an RO membrane device (RO membrane: reverse osmosis membrane ES-10 manufactured by Nitto Denko Corporation) for operation. Table 2 shows the results of measuring the TOC (total organic carbon) of the circulating water and the permeated water in this operation and comparing the RO membrane permeability of the drug as the TOC component.

  In general, it is known that a solute having a higher molecular weight is less permeable to the RO membrane. However, when Example 1 is compared with Comparative Example 1, it is a drug containing an alcohol having a molecular weight of 70 or more and a glycol-based organic solvent. However, when the organic solvent does not have the structure 1 or the structure 2 as described above, it can be seen that the RO membrane permeability of the TOC component is higher than that when the organic solvent has the structure. Further, even when the alcohol or glycol-based organic solvent contained therein has Structure 1 or Structure 2 as in Comparative Example 2, when the molecular weight is less than 70, the RO membrane permeability of the TOC component is high. Become. In addition, ethylene glycol, which is generally known as a DBNPA stabilizer, has a molecular weight of 70 or less and does not have Structure 1 or Structure 2 as described above, and therefore has a large transmission of the TOC component.

  Examples 2 and 3 and comparative examples 4 and 5 having a composition (% by weight) as shown in Table 3 were prepared. These were added to ultrapure water at 100 mg / L, respectively, and the water was passed through an RO membrane device (RO membrane: reverse osmosis membrane ES-10 manufactured by Nitto Denko Corporation) for operation. Table 4 shows the results of measuring the TOC (total organic carbon) of the circulating water and the permeated water and comparing the RO membrane permeability of the drug as the TOC component.

  If the organic solvent has the structure 1 or structure 2 as described above even if it is a drug containing an alcohol or glycol organic solvent having a molecular weight of 100 to 200 as in Examples 2 and 3, the TOC component Is difficult to permeate the RO membrane, and in the case of having no structure 1 or structure 2 even if the molecular weight is large (150 or more) as in Comparative Example 4, the transmittance of the TOC component is high. Further, even when the structure 1 or the structure 2 is not provided as in the comparative example 5, if the molecular weight is 200 or more, the transmittance of the TOC component is lowered.

Reference example 1
(Influence on RO membrane)
Test water in which sodium chloride and silica were added to ultrapure water, DBNPA, a halocyanoacetamide fungicide, was added to 60 mg / L as Reference Example 1, and only 10 minutes a day as Reference Comparative Example 1. The sample was added with sodium hypochlorite (effective chlorine 12%) added to make 1 mg / L of free chlorine, and the RO membrane device was run to compare the ion removal rates after 500 hours. The results are shown in Table 5. The RO membrane used was Nitto Denko's reverse osmosis membrane ES-10.

  From Table 5 above, it can be seen that DBNPA has a small effect on membrane performance compared to sodium hypochlorite and is at a level that does not cause any problems in actual use.

Reference example 2
(Comparison of bactericidal effect)
Bacteria are cultured, and test water containing approximately 10 ⁴ bacteria is treated with 5 mg / L of DBNPA as Reference Example 2 and CMI (5-chloro-) as a representative organic nitrogen-based fungicide as Reference Comparative Example 2. 2-methyl-4-isothiazolin-3-one) was added at 5 mg / L, and the number of bacteria after a predetermined time was measured. The results are shown in Table 6.

  From Table 6 above, it can be seen that DBNPA has a significantly higher bactericidal effect than CMI.

  Thus, in the present invention, the disinfectant, in particular, the halocyanoacetamide compound is dissolved in the alcohol or glycol-based organic solvent containing the specific structure 1 or structure 2 as described above. It can be added at a predetermined concentration. In addition, since the organic solvent contained has a specific structure 1 or structure 2, it is difficult to permeate the RO membrane, and as a result, compared to the case of using a conventional linear structure organic solvent, Deterioration of treated water quality can be significantly reduced.

The disinfectant for reverse osmosis membrane according to the present invention and the reverse osmosis membrane sterilization method using the same are particularly suitable for the reverse osmosis membrane sterilization treatment in the pure water and ultrapure water production process.

Claims (2)

A halocyanoacetamide compound represented by the general formula 1 of Chemical Formula 1 (wherein X is the same or different halogen atom or hydrogen atom, and R1 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms) Containing a bactericidal agent consisting of only tert-butanol, dipropylene glycol and tripropylene glycol, and passed through a reverse osmosis membrane in a pure water and ultrapure water production process. A fungicide for reverse osmosis membranes characterized by

A method for sterilizing a reverse osmosis membrane comprising sterilizing a reverse osmosis membrane comprising a polyamide-based composite membrane using the bactericide for reverse osmosis membrane according to claim 1 .