WO2016136304A1 - Method for modifying reverse osmosis membrane, reverse osmosis membrane, treatment method for boron-containing water, and method for operating separation membrane - Google Patents

Abstract

Provided is a method for modifying a reverse osmosis membrane for the purpose of improving the quality of water permeated through the reverse osmosis membrane, while suppressing deterioration of the reverse osmosis membrane. A method for modifying a reverse osmosis membrane, wherein: a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant and a sulfamic acid compound are brought into contact with a polyamide-based reverse osmosis membrane; or alternatively, a reaction product of a sulfamic acid compound and a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant is brought into contact with a polyamide-based reverse osmosis membrane.

Description

Reverse osmosis membrane modification method, reverse osmosis membrane, boron-containing water treatment method, and separation membrane operation method

The present invention relates to a method for modifying a polyamide-based reverse osmosis membrane, a reverse osmosis membrane modified by the modification method, a method for treating boron-containing water using the reverse osmosis membrane, and a method for operating a separation membrane.

There are many reforming methods for improving the quality of the permeated water of the reverse osmosis membrane (RO membrane). Among them, there is a method for improving performance by bringing a free chlorinated bromine into contact with a reverse osmosis membrane for a predetermined time.

For example, in Patent Document 1, in a membrane separation apparatus equipped with a reverse osmosis membrane element having a polyamide skin layer, after filling the reverse osmosis membrane element into a pressure vessel in the membrane separation apparatus, bromine is added to the reverse osmosis membrane element. A method for treating a reverse osmosis membrane element in which a free chlorine aqueous solution is brought into contact is described.

However, the method of Patent Document 1 can temporarily improve the water quality, but if a free chlorine aqueous solution containing bromine is passed for a long time, the reverse osmosis membrane deteriorates and the water quality decreases.

In the operation of polyamide separation membranes such as reverse osmosis membranes (RO membranes) and nanofiltration membranes (NF membranes), for example, when various bromine oxidants are used for the purpose of slime suppression, bromine oxidants It may flow into the separation membrane. Examples of the bromine-based oxidizing agent include a reaction product of an oxidizing agent such as hypochlorous acid and bromide ions, and hypobromite. However, these brominated oxidants are known to have a problem that the lower the pH of the water to be treated, the easier it is to reduce the amount of permeated water of the separation membrane (see Non-Patent Document 1).

JP 2003-088730 A

Desalination 280 (2011) 80-86

An object of the present invention is to provide a reverse osmosis membrane modification method for improving the quality of permeated water of a reverse osmosis membrane while suppressing deterioration of the reverse osmosis membrane, a reverse osmosis membrane modified by the modification method, and The object is to provide a method for treating boron-containing water using the reverse osmosis membrane.

Also, an object of the present invention is to provide a separation membrane operating method in which a decrease in the amount of permeated water is suppressed even when a bromine-based oxidant comes into contact with the separation membrane, and the separation membrane device is stably operated.

In the present invention, a polyamide-based reverse osmosis membrane is brought into contact with a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant and a sulfamic acid compound, or a bromine-based oxidant or a bromine compound. This is a method for modifying a reverse osmosis membrane in which a reaction product with a chlorine-based oxidant and a reaction product with a sulfamic acid compound are brought into contact with each other.

The present invention is a method for modifying a reverse osmosis membrane in which a polyamide-based reverse osmosis membrane is brought into contact with a mixture of bromine and a sulfamic acid compound or a reaction product of bromine and a sulfamic acid compound is brought into contact.

In the reverse osmosis membrane modification method, the reaction product of the bromine and the sulfamic acid compound is a step of reacting the mixed liquid containing water, alkali and sulfamic acid compound by adding bromine in an inert gas atmosphere. It is preferable that it was obtained by the method of including.

In the method for modifying a reverse osmosis membrane, it is preferable that the contact is performed in a pH range of 4 to 6.5.

In the method for modifying a reverse osmosis membrane, it is preferable that the polyamide-based reverse osmosis membrane is chlorinated with a chlorine-based oxidizing agent.

In the reverse osmosis membrane modification method, the contact is preferably performed at a pH of 5.5 or more.

The present invention is a reverse osmosis membrane modified by the method for modifying a reverse osmosis membrane.

The present invention is a method for treating boron-containing water in which boron-containing water is treated with a reverse osmosis membrane using the reverse osmosis membrane modified by the method for modifying a reverse osmosis membrane.

The present invention is also a method of operating a separation membrane in which a bromine-based oxidant is brought into contact with a polyamide-based separation membrane that has been chlorinated with a chlorinated oxidant.

In the operation method of the separation membrane, it is preferable that the pH of the water to be treated when the bromine-based oxidizing agent is brought into contact with the separation membrane is 5.5 or more.

In the operation method of the separation membrane, the bromine-based oxidant contains a bromine-based oxidant, a reaction product of a bromine compound and a chlorine-based oxidant, and a sulfamic acid compound, or a bromine-based oxidant, or It is preferable to contain a reaction product of a bromine compound and a chlorine-based oxidant and a reaction product of a sulfamic acid compound.

In the operation method of the separation membrane, it is preferable that the bromine-based oxidant contains a mixture of bromine and a sulfamic acid compound or a reaction product of bromine and a sulfamic acid compound.

In the method for operating the separation membrane, the reaction product of bromine and a sulfamic acid compound includes a step of reacting a mixed liquid containing water, an alkali and a sulfamic acid compound by adding bromine in an inert gas atmosphere. It is preferable that it was obtained by.

In the present invention, a reverse osmosis membrane modification method for improving the permeated water quality of a reverse osmosis membrane while suppressing deterioration of the reverse osmosis membrane, a reverse osmosis membrane modified by the modification method, and the reverse thereof A method for treating boron-containing water using an osmotic membrane can be provided.

Further, in the operation method of the separation membrane of the present invention, the separation membrane is subjected to chlorination in advance, so that a decrease in the amount of permeated water is suppressed even if a bromine-based oxidant comes into contact with the separation membrane, and stable. The separation membrane device can be operated.

Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Reverse osmosis membrane modification method and reverse osmosis membrane>
In the method for modifying a reverse osmosis membrane according to the embodiment of the present invention, a polyamide-based reverse osmosis membrane is contacted with a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent, and a sulfamic acid compound. Alternatively, it is a method of bringing a reaction product of a sulfamic acid compound into contact with a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant. Further, the reverse osmosis membrane according to the embodiment of the present invention is a reverse osmosis membrane modified by the method for modifying a reverse osmosis membrane. Here, “reformation” of the reverse osmosis membrane in this specification may refer to improvement of permeate quality and improvement of permeate quality (that is, improvement of the rejection rate). In some cases, it refers to suppression of decrease (that is, suppression of decrease in blocking rate).

In the method for modifying a reverse osmosis membrane according to an embodiment of the present invention, a “bromine-based oxidizing agent” and a “sulfamic acid compound” are present as modifiers in water supply to a polyamide-based reverse osmosis membrane. And a method of bringing the polyamide-based reverse osmosis membrane into contact with the polyamide-based reverse osmosis membrane, or a method of bringing a “reaction product of a bromine compound and a chlorine-based oxidant” and a “sulfamic acid compound” into contact with the polyamide-based reverse osmosis membrane. Thereby, it is thought that a hypobromite stabilization composition produces | generates in water supply etc.

In addition, the method for reforming a reverse osmosis membrane according to an embodiment of the present invention includes a reaction product of a bromine-based oxidant and a sulfamic acid compound as a modifier in water supply to a polyamide-based reverse osmosis membrane. Or a reaction product of a reaction product of a bromine compound and a chlorine-based oxidant and a sulfamic acid compound. In the presence of a hypobromite stabilizing composition, which is in contact with a polyamide-based reverse osmosis membrane.

Specifically, the method for modifying a reverse osmosis membrane according to an embodiment of the present invention includes, for example, “bromine”, “bromine chloride”, “hypobromite” in water supply to a polyamide-based reverse osmosis membrane. Or “reaction product of sodium bromide and hypochlorous acid” and “sulfamic acid compound” are present and brought into contact with the polyamide-based reverse osmosis membrane.

The reverse osmosis membrane modification method according to the embodiment of the present invention includes, for example, “reaction product of bromine and sulfamic acid compound”, “bromine chloride” in water supply to a polyamide-based reverse osmosis membrane. The reaction product of sulfamic acid compound and sulfamic acid compound "or" reaction product of sodium bromide and hypochlorous acid and sulfamic acid compound "is present. This is a method of contacting with a polyamide-based reverse osmosis membrane. In addition, it is not clear what kind of compound is generated as “reaction product of bromine and sulfamic acid compound”, but “bromosulfamic acid” which is a hypobromite stabilizing compound is generated. Conceivable.

These methods can improve the reverse osmosis membrane rejection and improve the permeate quality while suppressing the deterioration of the reverse osmosis membrane. Since the hypobromite stabilizing composition hardly deteriorates the polyamide-based reverse osmosis membrane, it is not a temporary improvement in water quality, but the water containing the above modifier is used as a polyamide-based reverse osmosis membrane for a long time. Even if the water is passed through and contacted, the deterioration of the reverse osmosis membrane is suppressed, and the reduction of the blocking rate of the reverse osmosis membrane, that is, the deterioration of water quality is suppressed.

In the method for reforming a reverse osmosis membrane according to the present embodiment, for example, during operation of a reverse osmosis membrane device including a polyamide-based reverse osmosis membrane, “bromine oxidant” or What is necessary is just to inject | pour the "reaction product of a bromine compound and a chlorine-type oxidizing agent", and a "sulfamic acid compound" with a chemical injection pump etc. “Brominated oxidant” or “reaction product of bromine compound and chlorinated oxidant” and “sulfamic acid compound” may be added separately to the feed water, or mixed with the stock solution before feeding water. It may be added inside. Further, for example, a polyamide-based reverse osmosis membrane is immersed for a predetermined time in water to which “bromine-based oxidant” or “reaction product of bromine compound and chlorine-based oxidant” and “sulfamic acid compound” are added. And may be contacted.

Also, for example, during the water supply to the polyamide-based reverse osmosis membrane, “reaction product of bromine-based oxidant and sulfamic acid compound” or “reaction product of bromine-based compound and chlorine-based oxidant and sulfamic acid compound” And “the reaction product of” may be injected by a chemical injection pump or the like. In addition, for example, in a water to which “reaction product of bromine-based oxidant and sulfamic acid compound” or “reaction product of bromine-based compound and chlorine-based oxidant and sulfamic acid compound” is added. Alternatively, the polyamide-based reverse osmosis membrane may be immersed and contacted for a predetermined time.

The modification with the modifier is performed by, for example, continuously or intermittently adding the modifier to the water supplied to the reverse osmosis membrane during the operation of the reverse osmosis membrane apparatus including the polyamide-based reverse osmosis membrane. Alternatively, when the blocking rate of the reverse osmosis membrane decreases, the above modifier is added continuously or intermittently to the water supplied to the reverse osmosis membrane, or the reverse osmosis membrane is placed in the water containing the modifier. It may be immersed.

The contact of the modifier with the reverse osmosis membrane may be performed under normal pressure, pressurized or reduced pressure conditions, but the modification can be performed without stopping the reverse osmosis membrane device. It is preferable to perform under pressure conditions from the viewpoint that the osmosis membrane can be reliably modified. The contact of the modifier with the reverse osmosis membrane is preferably performed under a pressurized condition in the range of 0.1 MPa to 8.0 MPa, for example.

The contact of the modifier with the reverse osmosis membrane may be performed under a temperature condition in the range of 5 ° C to 35 ° C, for example.

The ratio of the equivalent of “sulfamic acid compound” to the equivalent of “bromine-based oxidizing agent” or “reaction product of bromine compound and chlorine-based oxidizing agent” is preferably 1 or more, and is in the range of 1 or more and 2 or less. It is more preferable. If the ratio of the equivalent of “sulfamic acid compound” to the equivalent of “bromine-based oxidant” or “reaction product of bromine compound and chlorine-based oxidant” is less than 1, the reverse osmosis membrane may be deteriorated, If it exceeds 2, the production cost may increase.

The effective halogen concentration in contact with the reverse osmosis membrane is preferably 0.01 to 100 mg / L in terms of effective chlorine concentration. If it is less than 0.01 mg / L, a sufficient reforming effect may not be obtained. If it exceeds 100 mg / L, reverse osmosis membrane deterioration and piping corrosion may occur.

Examples of bromine-based oxidizing agents include bromine (liquid bromine), bromine chloride, bromic acid, bromate, and hypobromite.

Among these, the preparation of “bromine and sulfamic acid compound (mixture of bromine and sulfamic acid compound)” or “reaction product of bromine and sulfamic acid compound” using bromine is composed of “hypochlorous acid and bromine compound and Compared to sulfamic acid preparations and bromine chloride and sulfamic acid preparations, etc., there is less chloride ion, which does not degrade polyamide reverse osmosis membranes more and may cause corrosion of metal materials such as piping. Since it is low, it is more preferable.

That is, in the method for modifying a reverse osmosis membrane according to an embodiment of the present invention, a polyamide-based reverse osmosis membrane is brought into contact with bromine and a sulfamic acid compound (a mixture of bromine and a sulfamic acid compound is brought into contact), or It is preferable to contact the reaction product of bromine and a sulfamic acid compound.

Examples of bromine compounds include sodium bromide, potassium bromide, lithium bromide, ammonium bromide and hydrobromic acid. Of these, sodium bromide is preferable from the viewpoint of formulation cost and the like.

Examples of the chlorine-based oxidizing agent include chlorine gas, chlorine dioxide, hypochlorous acid or a salt thereof, chlorous acid or a salt thereof, chloric acid or a salt thereof, perchloric acid or a salt thereof, chlorinated isocyanuric acid or a salt thereof. Etc. Among these, examples of the salt include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite, alkaline earth hypochlorite such as calcium hypochlorite and barium hypochlorite. Metal salts, alkali metal chlorites such as sodium chlorite and potassium chlorite, alkaline earth metal chlorites such as barium chlorite, and other metal chlorites such as nickel chlorite , Alkali metal chlorates such as ammonium chlorate, sodium chlorate and potassium chlorate, and alkaline earth metal chlorates such as calcium chlorate and barium chlorate. These chlorine-based oxidants may be used alone or in combination of two or more. As the chlorine-based oxidant, sodium hypochlorite is preferably used from the viewpoint of handleability.

The sulfamic acid compound is a compound represented by the following general formula (1).
R ₂ NSO ₃ H (1)
(In the formula, R is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

Examples of the sulfamic acid compound include sulfamic acid (amidosulfuric acid) in which both two R groups are hydrogen atoms, N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N- A sulfamic acid compound in which one of two R groups such as isopropylsulfamic acid and N-butylsulfamic acid is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms, N, N-dimethylsulfamic acid, N, Two R groups such as N-diethylsulfamic acid, N, N-dipropylsulfamic acid, N, N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, N-methyl-N-propylsulfamic acid, etc. One of two R groups such as a sulfamic acid compound, N-phenylsulfamic acid and the like, both of which are alkyl groups having 1 to 8 carbon atoms Is a hydrogen atom and the other sulfamic acid compound or a salt thereof, such as an aryl group having 6 to 10 carbon atoms. Examples of the sulfamate include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, strontium salt and barium salt, manganese salt, copper salt, zinc salt, iron salt, cobalt salt, Other metal salts such as nickel salts, ammonium salts, guanidine salts and the like can be mentioned. The sulfamic acid compounds and salts thereof may be used alone or in combination of two or more. As the sulfamic acid compound, sulfamic acid (amidosulfuric acid) is preferably used from the viewpoint of environmental load.

In the method for reforming a reverse osmosis membrane according to the present embodiment, an alkali may be further present. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide. From the viewpoint of product stability at low temperatures, sodium hydroxide and potassium hydroxide may be used in combination. Further, the alkali is not solid and may be used as an aqueous solution.

The method for reforming a reverse osmosis membrane according to the present embodiment can be applied to a polyamide polymer membrane, which is currently mainstream as a reverse osmosis membrane. Polyamide polymer membranes have a relatively low resistance to oxidizing agents, and when free chlorine or the like is continuously brought into contact with the polyamide polymer membrane, the membrane performance is significantly reduced. However, in the method for modifying a reverse osmosis membrane according to the present embodiment, such a remarkable decrease in membrane performance hardly occurs even in a polyamide polymer membrane.

In the method for modifying a reverse osmosis membrane according to the present embodiment, the contact of the modifier with a polyamide-based reverse osmosis membrane is preferably performed in a range of more than pH 3 and less than 8, preferably pH 4 to 6.5. More preferably, it is performed in a range. When contact of the modifier with the polyamide-based reverse osmosis membrane is performed at a pH of 3 or less, deterioration of the reverse osmosis membrane occurs when the modifier is contacted with the polyamide-based reverse osmosis membrane for a long period of time. May occur, and the rejection rate may decrease, and if it is performed at 8 or more, the reforming effect may be insufficient. In particular, when contact is made in the range of pH 4 to 6.5, the permeated water quality of the reverse osmosis membrane can be sufficiently improved while suppressing the deterioration of the reverse osmosis membrane. In order to perform the contact of the modifier in the above pH range, for example, the pH of the water supplied to the reverse osmosis membrane may be maintained in the above range, or the pH of the reverse osmosis membrane immersion liquid may be maintained in the above range. Good.

In a reverse osmosis membrane apparatus having a polyamide-based reverse osmosis membrane, when scale is generated at pH 5.5 or higher of water supplied to the reverse osmosis membrane, a dispersant is used as a bromine-based oxidant or hypobromine to suppress the scale. You may use together with an acid stabilization composition. Examples of the dispersant include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of the dispersant added to the feed water is, for example, in the range of 0.1 to 1,000 mg / L as the concentration in the RO concentrated water.

In addition, in order to suppress the occurrence of scale without using a dispersant, for example, reverse osmosis is performed so that the silica concentration in RO concentrated water is less than the solubility and the Langeria index, which is a calcium scale index, is less than 0. Adjusting the operating conditions such as the recovery rate of the membrane device.

In the reverse osmosis membrane modification method according to this embodiment, it is preferable that the reverse osmosis membrane is chlorinated with a chlorine-based oxidant. That is, a polyamide-type reverse osmosis membrane chlorinated with a chlorine-based oxidant is brought into contact with a sulfamic acid compound and a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant as a modifier. Alternatively, a reaction product of a sulfamic acid compound is brought into contact with a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent.

In the method for modifying a reverse osmosis membrane according to an embodiment of the present invention, a polyamide-based reverse osmosis membrane is supplied with water or washed with water and washed with a chlorinated oxidant. It is the method of making it exist and contacting. A modifier may be present in contact with water supplied to a polyamide reverse osmosis membrane chlorinated with a chlorine-based oxidizing agent.

By these methods, the amount of permeated water and the quality of the permeated water can be controlled while sufficiently degrading the separation membrane by bringing the polyamide-based separation membrane into sufficient contact with the chlorinated oxidant in advance and treating with chlorine, and further bringing the modifier into contact. Improved.

The contact of the chlorinated oxidant and the modifier with the reverse osmosis membrane may be performed under normal pressure, pressure or reduced pressure, but the reverse osmosis membrane can be reliably modified, etc. From this point, it is preferable to carry out under pressurized conditions. The contact of the chlorine-based oxidizing agent and the modifier with the reverse osmosis membrane is preferably performed under a pressurized condition in the range of 0.1 MPa to 10 MPa, for example.

The contact of the chlorine-based oxidant and the modifier with the reverse osmosis membrane may be performed under a temperature condition in the range of 0 ° C. to 100 ° C., for example.

The contact of the chlorine-based oxidizing agent with the reverse osmosis membrane is preferably 0.1 to 1000 mg-Cl / L · hr as a value of effective chlorine concentration [mg-Cl / L] × time [hr]. If it is less than 0.1 mg-Cl / L · hr, a sufficient chlorination effect cannot be obtained for the film, and if it exceeds 1000 mg-Cl / L · hr, the film may be deteriorated.

The pH of the water to be treated when the chlorinated oxidant comes into contact is preferably in the range of 4 to 13, more preferably in the range of 6 to 12. When the pH is less than 4, the amount of permeated water may decrease, and when the pH exceeds 13, the reverse osmosis membrane may deteriorate.

The pH of the water to be treated when the modifier comes into contact with the reverse osmosis membrane chlorinated with a chlorinated oxidant is preferably 5.5 or higher, more preferably 6.0 or higher, and pH 6. More preferably, it is in the range of 5-10. If the modifier is contacted with a polyamide-based reverse osmosis membrane chlorinated with a chlorinated oxidant at a pH of less than 5.5, if the pH is less than 5.5, the reverse osmosis membrane is previously chlorinated. Even if it is, it may be affected by the decrease in the amount of permeated water by the modifier. If the pH exceeds 10, the amount of permeated water may increase too much.

In the method for modifying a separation membrane according to the present embodiment, the modifying agent is a “hypobromite stabilizing composition”. The “hypobromite stabilizing composition” has little adverse effect on the blocking rate of the reverse osmosis membrane, and even when continuously added to the chlorinated reverse osmosis membrane, the reforming effect is high.

The method for reforming a reverse osmosis membrane according to an embodiment of the present invention is, for example, in the presence of a chlorine-based oxidant in water supply to a polyamide-based reverse osmosis membrane and the like. A method of contacting a polyamide-based reverse osmosis membrane in the presence of “bromine-based oxidant” and “sulfamic acid compound”, or “reaction product of bromine compound and chlorine-based oxidant” and “sulfamic acid compound” It is a method of making it exist and making it contact with a polyamide-type reverse osmosis membrane. Thereby, it is thought that a hypobromite stabilization composition produces | generates in water supply etc.

The method for modifying a reverse osmosis membrane according to an embodiment of the present invention is, for example, a method in which a chlorinated oxidant is present in contact with water in a polyamide-based reverse osmosis membrane and the like, and then the modifier is contacted. As a method of contacting a polyamide-based reverse osmosis membrane with a hypobromite-stabilizing composition which is a “reaction product of a bromine-based oxidant and a sulfamic acid compound”, or “a bromine compound and a chlorine-based oxidation” This is a method in which a hypobromite stabilizing composition, which is a reaction product of a reaction product with an agent and a sulfamic acid compound, is present and brought into contact with a polyamide-based reverse osmosis membrane.

Specifically, the method for reforming a reverse osmosis membrane according to an embodiment of the present invention includes, for example, supplying a polyamide-based reverse osmosis membrane with water in the presence of a chlorinated oxidant, and then modifying the reverse osmosis membrane. A method of contacting a polyamide-based reverse osmosis membrane in the presence of “bromine”, “bromine chloride” or “reaction product of sodium bromide and hypochlorous acid” and “sulfamic acid compound” as a filler. It is.

The method for modifying a reverse osmosis membrane according to an embodiment of the present invention is, for example, a method in which a chlorinated oxidant is present in contact with water in a polyamide-based reverse osmosis membrane and the like, and then the modifier is contacted. As "reaction product of bromine and sulfamic acid compound", "reaction product of bromine chloride and sulfamic acid compound", or "reaction product of sodium bromide and hypochlorous acid, sulfamic acid compound, This is a method in which a hypobromite stabilizing composition as a reaction product is present and brought into contact with a polyamide-based reverse osmosis membrane.

In the reverse osmosis membrane modification method according to the present embodiment, for example, during operation of a reverse osmosis membrane device including a polyamide-based reverse osmosis membrane, water supply to the polyamide-based reverse osmosis membrane, etc. After injecting an oxidant with a chemical injection pump, etc., as a modifier, use a bromine oxidant or a reaction product of a bromine compound and a chlorinated oxidant, and a sulfamic acid compound as a chemical injection pump, etc. May be injected. The “bromine-based oxidant” or “reaction product of bromine compound and chlorine-based oxidant” and the “sulfamic acid compound” may be added separately to the feed water or the like, or mixed with the stock solution. May be added to the water supply. Further, for example, a polyamide-based reverse osmosis membrane may be immersed and contacted in water to which a chlorine-based oxidizing agent or a modifier is added for a predetermined time.

In addition, for example, after injecting a chlorine-based oxidizing agent into a polyamide-based reverse osmosis membrane with a chemical injection pump, etc., as a modifier, “reaction product of bromine-based oxidizing agent and sulfamic acid compound” Or a reaction product of a reaction product of a bromine compound and a chlorine-based oxidizing agent and a sulfamic acid compound ”may be injected by a chemical injection pump or the like. Further, for example, a polyamide-based reverse osmosis membrane may be immersed and contacted in water to which a chlorine-based oxidizing agent or a modifier is added for a predetermined time.

The modification with the chlorinated oxidant or the modifier is performed by, for example, supplying the chlorinated oxidant or the above-mentioned modified water into the reverse osmosis membrane during the operation of the reverse osmosis membrane apparatus including the polyamide-based reverse osmosis membrane. What is necessary is just to add a quality agent continuously or intermittently.

The bromine-based oxidizing agent, bromine compound, chlorine-based oxidizing agent, and sulfamic acid compound are as described above.

Among the bromine-based oxidants, the preparation of “bromine and sulfamic acid compound” or “reaction product of bromine and sulfamic acid compound” using bromine is the preparation of “hypochlorous acid, bromine compound and sulfamic acid” and Less chloride ions, less polyamide-based reverse osmosis membranes, and less effective halogen leakage into membrane permeate such as RO permeate compared to “bromine chloride and sulfamic acid” formulations Therefore, it is more preferable as a slime inhibitor for reverse osmosis membranes. Further, it is more preferable because it is less likely to cause corrosion of metal materials such as piping.

That is, in the method for modifying a reverse osmosis membrane according to an embodiment of the present invention, after bringing a polyamide-based reverse osmosis membrane into contact with a chlorine-based oxidant, bromine and a sulfamic acid compound are used as the modifier. It is preferable to contact with each other, or to contact a reaction product of bromine and a sulfamic acid compound.

Examples of the use of the reverse osmosis membrane device including the polyamide-based reverse osmosis membrane modified by the reverse osmosis membrane modification method according to this embodiment include seawater desalination and wastewater recovery. In particular, it is preferable to treat the boron-containing water with a reverse osmosis membrane using a polyamide-based reverse osmosis membrane modified by the reverse osmosis membrane modification method according to the present embodiment. By modifying the polyamide-based reverse osmosis membrane by the reverse osmosis membrane modification method according to this embodiment, the boron rejection rate is significantly improved.

<Operation method of separation membrane>
The operation method of the separation membrane according to the embodiment of the present invention is a method in which a bromine-based oxidizing agent is brought into contact with a polyamide-based separation membrane that has been chlorinated with a chlorine-based oxidizing agent.

In the operation method of the separation membrane according to the embodiment of the present invention, after bringing the chlorinated oxidant into contact with the supply water or the washing water to the polyamide-based separation membrane, the bromine-based oxidant is present. It is a method of making contact. A bromine-based oxidant may be present in contact with the polyamide-type separation membrane chlorinated with a chlorine-based oxidant, for example. In addition, the operation method of the separation membrane according to this embodiment may use a separation membrane that has been contacted with a chlorine-based oxidant in advance, and may contact the bromine-based oxidant on-site, or the separation membrane on-site. After contacting the chlorine-based oxidizing agent, the bromine-based oxidizing agent may be contacted.

By these methods, a chlorine-based oxidant is sufficiently brought into contact with a polyamide-based separation membrane in advance to perform chlorination, and even if a bromine-based oxidant comes into contact with the separation membrane, a decrease in the amount of permeated water is suppressed and stable. The separation membrane device can be operated. Chlorine is introduced into the material of the separation membrane by previously contacting the separation membrane with a chlorine-based oxidant. In a membrane into which chlorine has been introduced, bromine is less likely to be introduced, so it is generally assumed that the membrane is less susceptible to the influence of a bromine-based oxidant that causes a reduction in the amount of permeated water.

The contact of the chlorine-based oxidant and bromine-based oxidant to the separation membrane may be performed under normal pressure, pressurized or reduced pressure conditions, but the separation membrane can be reliably chlorinated. In view of being able to perform contact treatment while producing water, it is preferable to carry out under pressure. The contact of the chlorine-based oxidant and bromine-based oxidant with the separation membrane is preferably performed under a pressurized condition in the range of 0.1 MPa to 10 MPa, for example.

The contact of the chlorine-based oxidant and bromine-based oxidant with the separation membrane may be performed under temperature conditions in the range of 0 ° C. to 100 ° C., for example.

The contact of the chlorine-based oxidizing agent with the separation membrane is preferably 0.1 to 1000 mg-Cl / L · hr as a value of effective chlorine concentration [mg-Cl / L] × time [hr]. If it is less than 0.1 mg-Cl / L · hr, a sufficient chlorination effect cannot be obtained for the film, and if it exceeds 1000 mg-Cl / L · hr, the film may be deteriorated.

The effective halogen concentration by the bromine-based oxidizing agent that contacts the separation membrane is preferably 0.01 to 100 mg / L in terms of effective chlorine concentration. If it is less than 0.01 mg / L, a sufficient slime-inhibiting effect may not be obtained. If it is more than 100 mg / L, there is a possibility of causing deterioration of the separation membrane and corrosion of the piping.

The pH of the water to be treated when the chlorinated oxidant comes into contact is preferably in the range of 4 to 13, more preferably in the range of 6 to 12. When the pH is less than 4, the amount of permeated water may decrease, and when the pH exceeds 13, the separation membrane may deteriorate.

The pH of the water to be treated when the bromine-based oxidant comes into contact is preferably 5.5 or more, more preferably 6.0 or more, and even more preferably in the range of 6.5 to 10. When the pH is less than 5.5, even if the separation membrane has been subjected to chlorination in advance, it may be affected by a decrease in the amount of permeated water due to the bromine-based oxidizing agent. If the pH exceeds 10, the amount of permeated water may increase too much.

In the operation method of the separation membrane according to this embodiment, the bromine-based oxidant is not particularly limited. Examples of bromine-based oxidizing agents include “hypobromite” and the like, “reaction products of chlorine-based oxidizing agents and bromide ions”, “hypobromite stabilization composition”, etc. It is a “hypobromite stabilization composition”. The “hypobromite stabilizing composition” has little adverse effect on the rejection of the separation membrane, and can be stably operated for a long time even when continuously added to the chlorinated separation membrane.

For example, in a feed water to a polyamide-based separation membrane, a chlorinated oxidant is present and contacted, and then a “bromine-based oxidant” and a “sulfamic acid compound” are present to form a polyamide-based separation membrane. Or “reactant of bromine compound and chlorinated oxidant” and “sulfamic acid compound” are present in contact with the polyamide separation membrane. Thereby, it is thought that a hypobromite stabilization composition produces | generates in water supply etc.

In addition, for example, after supplying a polyamide-based separation membrane with a chlorine-based oxidizing agent in contact with water, etc., hypobromine which is a “reaction product of a bromine-based oxidizing agent and a sulfamic acid compound” Stabilize hypobromite in the presence of an acid stabilizing composition and contact with a polyamide separation membrane, or “reaction product of a bromine compound and a chlorinated oxidant and a sulfamic acid compound” The composition may be present in contact with the polyamide separation membrane.

Specifically, in the operation method of the separation membrane according to the embodiment of the present invention, for example, in the water supply to the polyamide-type separation membrane, after bringing the chlorinated oxidant into contact therewith, “bromine”, In this method, “bromine chloride” or “reaction product of sodium bromide and hypochlorous acid” and “sulfamic acid compound” are present and brought into contact with a polyamide separation membrane.

Further, the operation method of the separation membrane according to the embodiment of the present invention is, for example, a method in which a bromine and a sulfamic acid compound are contacted in the presence of a chlorine-based oxidizing agent in water supply to a polyamide-based separation membrane. "Reaction product of bromoamine and sulfamic acid compound", or "Reaction product of sodium bromide and hypochlorous acid and sulfamic acid compound" In this method, a bromite stabilizing composition is present and brought into contact with a polyamide separation membrane.

In the operation method of the separation membrane according to the present embodiment, for example, when operating a separation membrane device including a polyamide-based separation membrane, a chlorine-based oxidant is supplied to the separation membrane by using a chemical injection pump or the like. After injection, “bromine-based oxidant” or “reaction product of bromine compound and chlorine-based oxidant” and “sulfamic acid compound” may be injected by a chemical injection pump or the like. “Brominated oxidant” or “reaction product of bromine compound and chlorinated oxidant” and “sulfamic acid compound” may be added separately to the feed water, or mixed with the stock solution before feeding water. It may be added inside.

In addition, for example, after injecting a chlorine-based oxidant into a water supply to a polyamide-based separation membrane with a chemical pump or the like, a “reaction product of a bromine-based oxidant and a sulfamic acid compound” or “bromine A reaction product of a reaction product of a compound and a chlorine-based oxidant and a sulfamic acid compound ”may be injected by a chemical injection pump or the like.

The ratio of the equivalent of “sulfamic acid compound” to the equivalent of “bromine-based oxidizing agent” or “reaction product of bromine compound and chlorine-based oxidizing agent” is preferably 1 or more, and is in the range of 1 or more and 2 or less. It is more preferable. If the ratio of the equivalent amount of the “sulfamic acid compound” to the equivalent amount of the “bromine-based oxidant” or “reaction product of the bromine compound and the chlorine-based oxidant” is less than 1, the separation membrane may be deteriorated. If it exceeds, the manufacturing cost may increase.

The bromine-based oxidizing agent, bromine compound, chlorine-based oxidizing agent, and sulfamic acid compound are as described above.

Among the bromine-based oxidants, the preparation of “bromine and sulfamic acid compound” or “reaction product of bromine and sulfamic acid compound” using bromine is the preparation of “hypochlorous acid, bromine compound and sulfamic acid” and Compared to “bromine chloride and sulfamic acid” preparations, etc., it has less chloride ions, does not deteriorate the polyamide separation membrane, and has less leakage of effective halogen into membrane permeated water such as RO permeated water. More preferable as a slime inhibitor for separation membranes. Further, it is more preferable because it is less likely to cause corrosion of metal materials such as piping.

That is, in the operation method of the separation membrane according to the embodiment of the present invention, after bringing the chlorinated oxidant into contact with water or the like to the polyamide separation membrane, bromine and It is preferable to contact the sulfamic acid compound or to contact the reaction product of bromine and the sulfamic acid compound.

In the operation method of the separation membrane according to this embodiment, an alkali may be further present together with the bromine-based oxidizing agent. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide. From the viewpoint of product stability at low temperatures, sodium hydroxide and potassium hydroxide may be used in combination. Further, the alkali is not solid and may be used as an aqueous solution.

Examples of the separation membrane include a reverse osmosis membrane (RO membrane), a nanofiltration membrane (NF membrane), a microfiltration membrane (MF membrane), and an ultrafiltration membrane (UF membrane). Among these, the operation method of the separation membrane according to the embodiment of the present invention can be preferably applied to a reverse osmosis membrane (RO membrane). Moreover, the operation method of the separation membrane which concerns on embodiment of this invention is suitably applicable to the polyamide-type polymer membrane which is mainstream these days as a reverse osmosis membrane. Polyamide polymer membranes tend to decrease the amount of permeated water when they come into contact with bromine-based oxidants. For example, when free chlorine or the like is added in the presence of bromide ions, hypobromite is generated in water. When contacted with the polymer polymer membrane even temporarily, the permeated water amount significantly decreases. However, in the operation method of the separation membrane according to the present embodiment, such a remarkable decrease in membrane performance hardly occurs even in the polyamide polymer membrane.

In a reverse osmosis membrane apparatus having a polyamide-based reverse osmosis membrane, when scale is generated at pH 5.5 or higher of water supplied to the reverse osmosis membrane, a dispersant is used as a bromine-based oxidant or hypobromine to suppress the scale. You may use together with an acid stabilization composition. Examples of the dispersant include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of the dispersant added to the feed water is, for example, in the range of 0.1 to 1,000 mg / L as the concentration in the RO concentrated water.

In addition, in order to suppress the occurrence of scale without using a dispersant, for example, reverse osmosis is performed so that the silica concentration in RO concentrated water is less than the solubility and the Langeria index, which is a calcium scale index, is less than 0. Adjusting the operating conditions such as the recovery rate of the membrane device.

<Modifier composition>
The modifier composition used in the reverse osmosis membrane modification method and separation membrane operation method according to the present embodiment is a "bromine-based oxidant" or "a reaction product of a bromine compound and a chlorine-based oxidant" It contains “sulfamic acid compound” and may further contain alkali.

Further, the modifier composition according to the present embodiment is a "reaction product of a bromine-based oxidant and a sulfamic acid compound", or "a reaction product of a bromine compound and a chlorinated oxidant, a sulfamic acid compound, Of the reaction product ", and may further contain an alkali.

The bromine-based oxidizing agent, bromine compound, chlorine-based oxidizing agent, and sulfamic acid compound are as described above.

The modifier composition according to the present embodiment contains bromine and a sulfamic acid compound because the polyamide-based reverse osmosis membrane and the like are not further deteriorated and the amount of effective halogen leaked into the RO permeate is smaller. (Containing a mixture of bromine and sulfamic acid compound), for example, a mixture of bromine, sulfamic acid compound, alkali and water, or containing a reaction product of bromine and sulfamic acid compound, for example bromine A mixture of a reaction product of a sulfamic acid compound with an alkali, and water is preferable.

The modifier composition according to the present embodiment has a modification effect of a polyamide-based reverse osmosis membrane or the like, compared with a modifier such as hypochlorous acid or free chlorine containing bromine, but the following It hardly causes significant film deterioration such as chlorous acid and free chlorine containing bromine. At normal use concentrations, the effect on film degradation can be substantially ignored. Therefore, it is optimal as a modifier for polyamide-based reverse osmosis membranes.

Unlike the hypochlorous acid, free chlorine containing bromine and the like, the modifier composition according to the present embodiment hardly permeates the reverse osmosis membrane or the like, and therefore has little influence on the quality of treated water. Further, since the concentration can be measured on site in the same manner as hypochlorous acid or the like, more accurate concentration management is possible.

The pH of the composition is, for example, more than 13.0, more preferably more than 13.2. When the pH of the composition is 13.0 or less, the effective halogen in the composition may become unstable.

The bromate concentration in the modifier composition is preferably less than 5 mg / kg. When the bromate concentration in the modifier composition is 5 mg / kg or more, the concentration of bromate ions such as RO permeated water may increase.

<Method for producing modifier composition>
The modifier composition according to the present embodiment is obtained by mixing a bromine-based oxidant and a sulfamic acid compound, or by mixing a reaction product of a bromine compound and a chlorine-based oxidant and a sulfamic acid compound. Further, an alkali may be mixed.

As a method for producing a modifier composition containing bromine and a sulfamic acid compound, or a modifier composition containing a reaction product of bromine and a sulfamic acid compound, water, an alkali and a sulfamic acid compound are used. It is preferable to include a step of reacting by adding bromine to the mixed solution containing inert gas atmosphere or a step of adding bromine to the mixed solution containing water, alkali and sulfamic acid compound under inert gas atmosphere. By adding and reacting under an inert gas atmosphere, or adding under an inert gas atmosphere, the bromate ion concentration in the composition is lowered, and the bromate ion concentration in RO permeated water and the like is lowered. .

Although the inert gas to be used is not limited, at least one of nitrogen and argon is preferable from the viewpoint of production and the like, and nitrogen is particularly preferable from the viewpoint of manufacturing cost and the like.

The oxygen concentration in the reactor during the addition of bromine is preferably 6% or less, more preferably 4% or less, further preferably 2% or less, and particularly preferably 1% or less. If the oxygen concentration in the reactor during the bromine reaction exceeds 6%, the amount of bromic acid produced in the reaction system may increase.

The addition ratio of bromine is preferably 25% by weight or less, more preferably 1% by weight or more and 20% by weight or less based on the total amount of the composition. If the bromine addition rate exceeds 25% by weight relative to the total amount of the composition, the amount of bromic acid produced in the reaction system may increase. If it is less than 1% by weight, the reforming effect may be inferior.

The reaction temperature at the time of bromine addition is preferably controlled in the range of 0 ° C. to 25 ° C., but more preferably in the range of 0 ° C. to 15 ° C. from the viewpoint of production cost. When the reaction temperature at the time of bromine addition exceeds 25 degreeC, the production amount of the bromic acid in a reaction system may increase, and when it is less than 0 degreeC, it may freeze.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Preparation of Hypobromite Stabilizing Composition 1]
Under nitrogen atmosphere, liquid bromine: 16.9% by weight (wt%), sulfamic acid: 10.7% by weight, sodium hydroxide: 12.9% by weight, potassium hydroxide: 3.94% by weight, water: remaining The components were mixed to prepare Hypobromite Stabilized Composition 1. The pH of the hypobromite stabilizing composition 1 was 14, and the effective halogen concentration (effective chlorine equivalent concentration) was 7.5% by weight. The detailed preparation method of the hypobromite stabilization composition 1 is as follows.

Add 1436 g of water and 361 g of sodium hydroxide to a 2 L four-necked flask sealed by continuous injection while controlling the flow rate of nitrogen gas with a mass flow controller so that the oxygen concentration in the reaction vessel is maintained at 1%. Next, after adding 300 g of sulfamic acid and mixing, 473 g of liquid bromine was added while maintaining cooling so that the temperature of the reaction solution was 0 to 15 ° C., and 230 g of 48% potassium hydroxide solution was added. A target composition having a sulfamic acid 10.7% by weight ratio to the total amount of the composition, 16.9% bromine, and an equivalent ratio of sulfamic acid to an equivalent of bromine of 1.04 was obtained. The pH of the resulting solution was 14 as measured by the glass electrode method. The bromine content of the resulting solution was 16.9% as measured by a redox titration method using sodium thiosulfate after bromine was converted to iodine with potassium iodide, and the theoretical content (16.9% ) Of 100.0%. The oxygen concentration in the reaction vessel during the bromine reaction was measured using “Oxygen Monitor JKO-02 LJDII” manufactured by Zico Corporation. The bromic acid concentration was less than 5 mg / kg.

<Example 1, Comparative Examples 1 and 2>
Hypobromite stabilizing composition 1 prepared above (Example 1), hypochlorous acid (Comparative Example 1), hypobromite (mixture of sodium bromide and hypochlorous acid) (Comparative Example 2) Were used as modifiers to modify polyamide-based polymer reverse osmosis membranes (“ES20” manufactured by Nitto Denko Corporation, φ75 mm flat membrane, NaCl rejection reduced to 95%). . The reforming was carried out by passing water added with 1 ppm of the above modifier at pH = 5 and 25 ± 1 ° C. for 24 hours to the reverse osmosis membrane device equipped with this reverse osmosis membrane. . Thereafter, water with 500 ppm of sodium chloride (NaCl) and 1 ppm of the above modifier added at an operating pressure of 0.75 MPa was added at pH = 7, 25 ± 1 ° C. CT (Concentration Time) value = 1000 [ppm・ Continuous water flow until h]. The conductivity of raw water and permeated water was measured, and the following NaCl rejection was calculated. The CT value was calculated as follows. The results are shown in Table 1. In Comparative Example 2, sodium bromide: 15% by weight, 12% sodium hypochlorite aqueous solution: 42.4% by weight were added separately as water as modifiers.
NaCl rejection [%] = (100− [permeate conductivity / feed water conductivity] × 100)
CT value [ppm · h] = (Free chlorine concentration) × (Contact time)

Thus, by using the hypobromite stabilizing composition 1 of Example 1 as a modifier, it was possible to improve the permeated water quality of the reverse osmosis membrane while suppressing the deterioration of the reverse osmosis membrane. When the hypochlorous acid of Comparative Example 1 and the free chlorine containing bromine of Comparative Example 2 are used, the water quality can be temporarily improved. However, if water is passed for a long time, the reverse osmosis membrane deteriorates and the NaCl rejection rate Decreased.

<Example 2>
Using the hypobromite stabilizing composition 1 prepared above as a modifier, reforming and continuous water flow were performed under the same conditions as in Example 1, and the influence of the pH of the feed water to the reverse osmosis membrane was examined. . The results are shown in Table 2.

Thus, at pH = 3, the NaCl rejection rate was improved by the reforming, but when the water was continuously passed until the CT value after modification was 1000 [ppm · h], the NaCl rejection rate was slightly decreased. At pH = 8.0, the improvement of the NaCl rejection rate due to the reforming was small, but the decrease of the NaCl rejection rate due to continuous water flow did not occur. In the range of pH 4 to 6.5, the NaCl rejection rate was improved by the reforming, and the NaCl rejection rate did not decrease even when water was continuously passed until the CT value after modification was 1000 [ppm · h]. From this, it was found that the contact of the modifier with the polyamide-based reverse osmosis membrane is preferably performed in the range of more than pH 3 and less than 8, more preferably in the range of pH 4 to 6.5. .

<Example 3>
After performing the reverse osmosis membrane treatment of boron-containing water under the following conditions, the reverse osmosis membrane treatment was performed in the same manner as in Example 1, followed by the reverse osmosis membrane treatment of boron-containing water. The results are shown in Table 3.

(Experimental conditions)
Using the above-prepared hypobromite stabilizing composition 1 as a modifier, a polyamide polymer reverse osmosis membrane (“SWC5” 8-inch element manufactured by Nitto Denko Corporation, reduced to boron rejection = 78%) Reforming). For the modification, water with 4 ppm of the above-mentioned modifier added at an operating pressure of 6.0 MPa was passed through the reverse osmosis membrane apparatus having the reverse osmosis membrane at pH = 6.5, 24 ± 1 ° C. for 300 hours. Carried out. Thereafter, water to which 4 ppm of boron and 4 ppm of the above modifier were added was passed at an operating pressure of 6.0 MPa at pH = 7, 24 ± 1 ° C. The boron concentration of raw water, concentrated water and permeated water was measured by ICP emission spectroscopic analysis using an ICP emission spectroscopic analyzer (manufactured by SII Nanotechnology Inc., SPS3100), and the following boron rejection was calculated. The results are shown in Table 3.
Boron rejection [%] = 100− [permeated boron concentration ÷ {(feed water boron concentration + concentrated water boron concentration) ÷ 2} × 100]

Thus, when the reverse osmosis membrane was modified using the hypobromite stabilizing composition 1, the boron rejection was improved.

<Example 4>
Using the above-prepared hypobromite stabilizing composition 1 as a modifier, a polyamide polymer reverse osmosis membrane (“ES15” manufactured by Nitto Denko Corporation, reduced to NaCl rejection = 98.5%) Was improved). The reverse osmosis membrane was immersed for 72 hours at 25 ± 1 ° C. in water in which 1 ppm of the modifier was added to ultrapure water and the pH was adjusted to 7. Thereafter, a 500 ppm sodium chloride (NaCl) solution was passed at pH = 7 and 25 ± 1 ° C. at an operating pressure of 0.75 MPa. The conductivity of raw water and permeated water was measured, and the following NaCl rejection was calculated. The results are shown in Table 4.
NaCl rejection [%] = (100− [permeate conductivity / feed water conductivity] × 100)

Thus, it was confirmed that the reverse osmosis membrane was modified by the hypobromite stabilizing composition even under immersion conditions.

[Relationship between presence / absence of chlorination and decrease in permeated water volume when modifier water is passed]
The behavior of the amount of permeated water was compared between the separation membrane previously contacted with the chlorinated oxidant and the separation membrane not contacted with the chlorinated oxidant when the modifier was passed through.

(Chlorine treatment conditions)
RO membrane: polyamide polymer reverse osmosis membrane (water temperature: 25 ° C., operating pressure: 0.75 MPa, conductivity rejection of 2000 mg / L NaCl solution is 95% or more)
Chlorine treatment conditions: 10 mg-CL / L of sodium hypochlorite as effective chlorine was added to pure water, adjusted to pH 10, water flow for 1 hr at a pressure of 0.75 MPa and a water temperature of 25 ° C.

(Modifier flow conditions)
Test device: Flat membrane test device Separation membrane: Polyamide polymer reverse osmosis membrane (water temperature: 25 ° C., operating pressure: 0.75 MPa, conductivity rejection of 2000 mg / L NaCl solution is 95% or more ), Or reverse osmosis membrane with the above chlorination treatment and operating pressure: 0.75 MPa
・ Raw water: Sagamiharai water (conductivity 240μS / cm)
Test water pH: 6.5
・ Drug: Hypobromite stabilization composition 1 prepared above is added so that the effective halogen concentration (effective chlorine equivalent concentration) is 1 mg / L.

(Evaluation methods)
・ Effect on the amount of permeated water of the separation membrane: Permeated water retention rate after passing through 120 hours (%)
([Amount of permeated water after 120 hours of modifier water flow / Amount of permeated water before water of modifier] × 100)

<Example 5>
Hypobromite stabilizing composition 1 as a modifier was passed through the separation membrane subjected to the chlorination in advance under the above conditions. The results are shown in Table 5.

<Example 6>
Water was passed under the same conditions as in Example 5 except that the above separation membrane not subjected to chlorination was used. The results are shown in Table 5.

In Example 6, after passing the modifier, the permeated water amount decreased to less than 70% of the initial value, but in Example 5, the permeated water amount was maintained at 80% or more.

[Effect of pH when water passes through modifier]
(Modifier flow conditions)
Test device: Flat membrane test device Separation membrane: Polyamide polymer reverse osmosis membrane (water temperature: 25 ° C., operating pressure: 0.75 MPa, conductivity rejection of 2000 mg / L NaCl solution is 95% or more )
・ Operating pressure: 0.75 MPa
・ Raw water: Sagamiharai water (conductivity 240μS / cm)
Test water pH: 5.0 to 8.0
・ Drug: Hypobromite stabilization composition 1 prepared above is added so that the effective halogen concentration (effective chlorine equivalent concentration) is 1 mg / L.

(Evaluation methods)
・ Effect on the amount of permeated water of the separation membrane: Permeated water retention rate after passing through 120 hours (%)
([Amount of permeated water after 120 hours of modifier water flow / Amount of permeated water before water of modifier] × 100)

<Examples 7 to 10>
Hypobromite stabilizing composition 1 was passed through the separation membrane that had been previously chlorinated under conditions of pH 5.0 to 8.0. The results are shown in Table 6.

<Examples 11 to 14>
Hypobromite stabilizing composition 1 was passed through the separation membrane that had not been previously chlorinated under the conditions of pH 5.0 to 8.0. The results are shown in Table 6.

It was found that the pH of the water to be treated when the modifier is brought into contact with the separation membrane is preferably 5.5 or more, and more preferably 6.0 or more.

[Influence of modifier type]
(Test conditions)
・ Test equipment: Flat membrane test equipment ・ Separation membrane: Polyamide-based polymer reverse osmosis membrane (conductivity rejection in a 2000 mg / L NaCl solution is 95% or more) in advance. Chlorine treatment ・ Operating pressure: 0 .75 MPa
・ Raw water: Sagamiharai water (conductivity 240μS / cm)
Test water pH: 7.0
-Drug: Addition of hypobromite stabilization composition 1 or hypobromite stabilization composition 2 prepared above to an effective halogen concentration (effective chlorine equivalent concentration) of 10 mg / L-Test time : 64 days

(Evaluation methods)
-Conductivity rejection rate (%) in RO membrane before and after the test

(Hypobromite stabilization composition 2)
Sodium bromide: 11% by weight, 12% sodium hypochlorite aqueous solution: 50% by weight, sodium sulfamate: 14% by weight, sodium hydroxide: 8% by weight, water: the remainder was mixed to prepare hypobromite Stabilized composition 2 was prepared. The pH of the hypobromite stabilizing composition 2 was 14, and the effective halogen concentration (effective chlorine equivalent concentration) was 6% by weight. The detailed preparation method of the composition of the hypobromite stabilization composition 2 is as follows.

17 g of water was put into a reaction vessel, 11 g of sodium bromide was added and dissolved by stirring, 50 g of 12% aqueous sodium hypochlorite solution was added and mixed, and then 14 g of sodium sulfamate was added and stirred. After dissolution, 8 g of sodium hydroxide was added, stirred and dissolved to obtain the desired composition.

<Example 15>
Hypobromite stabilization composition 1 was passed through, and the conductivity rejection rate in the separation membrane before and after the test was measured. The results are shown in Table 7.

<Example 16>
Hypobromite stabilization composition 2 was passed through, and the conductivity rejection rate in the separation membrane before and after the test was measured. The results are shown in Table 7.

Both Examples 15 and 16 retained a conductivity rejection of 90% or more, but Example 15 showed a higher rejection.

[Effect of contact degree of chlorinated oxidant on separation membrane in chlorination]
(Test conditions)
Test device: Flat membrane test device Separation membrane: Polyamide polymer reverse osmosis membrane (water temperature: 25 ° C., operating pressure: 0.75 MPa, conductivity rejection of 2000 mg / L NaCl solution is 95% or more )
・ Operating pressure: 0.75 MPa
・ Raw water: Ultrapure water ・ Chlorine oxidizer: Sodium hypochlorite

(Evaluation methods)
-Conductivity rejection rate (%) in the separation membrane before and after the test

<Example 17>
The contact degree of the chlorine-based oxidant to the separation membrane was 10 mg-CL / L × hr. The results are shown in Table 8.

<Example 18>
The degree of contact of the chlorine-based oxidant with the separation membrane was 1034 mg-CL / L × hr. The results are shown in Table 8.

The conductivity rejection was 90% or more in Example 17, but decreased to less than 90% in Example 18.

As described above, by performing chlorination on the separation membrane in advance, even if the modifier comes into contact with the separation membrane thereafter, a decrease in the amount of permeate is suppressed, and the separation membrane device can be operated stably. I understood. In addition, it was found that the permeated water amount and the permeated water quality can be improved while the deterioration of the separation membrane is suppressed by bringing the reforming agent into contact with the separation membrane after chlorination in advance.

Claims (13)

A polyamide-based reverse osmosis membrane is contacted with a bromine-based oxidant or a reaction product of a bromine compound and a chlorine-based oxidant and a sulfamic acid compound, or a bromine-based oxidant, or a bromine compound and a chlorine-based oxidant. A method for reforming a reverse osmosis membrane, comprising contacting a reaction product with a reaction product of a sulfamic acid compound. A method for modifying a reverse osmosis membrane, comprising contacting a polyamide-based reverse osmosis membrane with a mixture of bromine and a sulfamic acid compound or a reaction product of bromine and a sulfamic acid compound. A method for modifying a reverse osmosis membrane according to claim 2,
The reaction product of bromine and a sulfamic acid compound is obtained by a method including a step of reacting a mixed liquid containing water, an alkali and a sulfamic acid compound by adding bromine in an inert gas atmosphere. A method for reforming a reverse osmosis membrane characterized by the above. A method for reforming a reverse osmosis membrane according to any one of claims 1 to 3,
A method for modifying a reverse osmosis membrane, wherein the contact is performed in a pH range of 4 to 6.5. A method for reforming a reverse osmosis membrane according to any one of claims 1 to 3,
A method for modifying a reverse osmosis membrane, wherein the polyamide-based reverse osmosis membrane is chlorinated with a chlorine-based oxidizing agent. A method for modifying a reverse osmosis membrane according to claim 5,
A method for modifying a reverse osmosis membrane, wherein the contact is performed at a pH of 5.5 or more. A reverse osmosis membrane, which is modified by the reverse osmosis membrane modification method according to any one of claims 1 to 6. A treatment of boron-containing water, characterized by treating the boron-containing water with a reverse osmosis membrane using the reverse osmosis membrane modified by the reverse osmosis membrane modification method according to any one of claims 1 to 6. Method. A method for operating a separation membrane, characterized by bringing a bromine-based oxidant into contact with a polyamide-based separation membrane that has been chlorinated with a chlorine-based oxidant. The operation method of the separation membrane according to claim 9,
A method for operating a separation membrane, wherein the pH of the water to be treated when the bromine-based oxidizing agent is brought into contact with the separation membrane is 5.5 or more. The operation method of the separation membrane according to claim 9 or 10,
The bromine-based oxidant contains a bromine-based oxidant, a reaction product of a bromine compound and a chlorine-based oxidant, and a sulfamic acid compound, or a bromine-based oxidant, or a bromine compound and a chlorine-based oxidant. A method for operating a separation membrane, comprising a reaction product of a reaction product of the above and a sulfamic acid compound. The operation method of the separation membrane according to claim 11,
The method for operating a separation membrane, wherein the bromine-based oxidizing agent contains bromine and a sulfamic acid compound, or contains a reaction product of bromine and a sulfamic acid compound. The operation method of the separation membrane according to claim 12,
The reaction product of bromine and a sulfamic acid compound is obtained by a method including a step of reacting a mixed liquid containing water, an alkali and a sulfamic acid compound by adding bromine in an inert gas atmosphere. A method of operating a separation membrane characterized by the above.