A reverse osmosis membrane in-situ repair reagent and a reverse osmosis membrane in-situ repair method

Abstract

The invention discloses an in-situ repair reagent for reverse osmosis membrane and an in-situ repair method for reverse osmosis membrane. The reverse osmosis membrane repair agent is composed of a repair agent A and a repair agent B, wherein the repair agent A is a mixed solution of dopamine hydrochloride, catechol, and tannic acid with a self-polymerizing polymer; and the repair agent B is a tris(hydroxymethyl)aminomethane hydrochloride) solution. The repair agent can perform in-situ repair on a reverse osmosis membrane with a desalination rate of 60-90%. The method can restore a reverse osmosis membrane with a desalination rate of 60-90% to a desalination rate of more than 95%, and the water flux of the repaired membrane is close to that of the original membrane. The repair agent has low cost, is environmentally friendly, and has a stable repair effect.

Description

Technical Field

[0001] The invention relates to the technical field of reverse osmosis, and in particular to a reverse osmosis membrane in-situ repair reagent and a reverse osmosis membrane in-situ repair method. Background Art

[0002] In recent years, reverse osmosis technology has been widely used in the field of water treatment, but the problem that reverse osmosis membranes are easily damaged by oxidation, resulting in deterioration of membrane separation performance, has become the main bottleneck restricting its further development and application. Although reverse osmosis membranes with certain oxidation resistance have been developed, oxidative degradation and performance decay will still occur after long-term use. It is estimated that general reverse osmosis membrane elements need to be replaced with new membranes after 3 to 5 years of use, but directly replacing reverse osmosis membranes will cause environmental pollution and waste of resources. Repairing and treating degraded or abandoned reverse osmosis membranes can restore separation performance, extend service life, reduce replacement costs and reduce environmental pollution.

[0003] In membrane repair research, degraded reverse osmosis membranes are often repaired by surface modification methods (including coating and chemical grafting). This method is often only applicable to the repair of reverse osmosis membranes with a specific desalination rate, and there are few repair reagents and methods that can be applied to reverse osmosis membranes with different degrees of deterioration and desalination rates. Therefore, it is urgent to develop repair reagents and methods for reverse osmosis membranes with different degrees of deterioration, so as to repair degraded or abandoned reverse osmosis membranes with different desalination rates to a level close to that of the original membrane, while ensuring that the repaired reverse osmosis membrane has good water permeability. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a reverse osmosis membrane in-situ repair reagent and a reverse osmosis membrane in-situ repair method, which repairs deteriorated or abandoned reverse osmosis membranes with different desalination rates to a level with a desalination rate close to that of the original membrane.

[0005] The first object of the present invention is to provide an in-situ repair reagent for reverse osmosis membrane, comprising a repair agent A and a repair agent B, wherein the repair agent A comprises, by weight, 50 to 80 parts of a mixed solution of a self-polymerizing high molecular polymer, 20 to 50 parts of deionized water (deionized), and a pH value of 7.0 to 8.5;

[0006] The repair agent B comprises: 0.5 to 5 parts of tris(hydroxymethyl)aminomethane hydrochloride solution, 95 to 99.5 parts of deionized water, and a pH value of 8.5 to 10.0.

[0007] In some embodiments of the present invention, the mixed solution of the self-polymerizing polymer is prepared by the following method:

[0008] S1. Prepare a mixed solution of dopamine hydrochloride, catechol, tannic acid and deionized water, perform ultrasonic treatment, pass inert gas to deoxygenate and continue stirring;

[0009] S2. The mixed solution obtained in step S1 after deoxygenation and stirring is allowed to stand, and dopamine hydrochloride, catechol and tannic acid are added to the mixed solution every 4 to 8 hours, and then ultrasonically treated and mixed, and oxygen is removed by passing an inactive gas, and the mixed solution with the self-polymerizing high molecular polymer is obtained at a constant temperature.

[0010] In some embodiments of the present invention, in step S1, the amount of dopamine hydrochloride is 0.05-0.5 parts, the amount of catechol is 0.05-0.5 parts, the amount of tannic acid is 0.05-0.5 parts and the amount of deionized water is 100 parts.

[0011] In some embodiments of the present invention, in step S2, the standing temperature of the mixed solution is 20-25°C;

[0012] The dosage of dopamine hydrochloride is 0.05-0.5 parts, the dosage of catechol is 0.05-0.5 parts, the dosage of tannic acid is 0.05-0.5 parts and the dosage of deionized water is 100 parts;

[0013] The constant temperature is 20-25°C, and the constant temperature time is 24-36 hours.

[0014] The inert gas is selected from nitrogen and / or argon.

[0015] Preferably, the specific preparation steps of the mixed solution of the self-polymerizing high molecular polymer are:

[0016] First, 0.05-0.5 parts of dopamine hydrochloride, 0.05-0.5 parts of catechol, 0.05-0.5 parts of tannic acid and 100 parts of deionized water are prepared into an initial mixed solution, ultrasonically treated, nitrogen is passed through to deoxygenate, the temperature of the mixed solution is maintained at 20-25°C, magnetic stirring is performed, and nitrogen is continued to be passed through to deoxygenate. The resulting solution is then allowed to stand at 20-25°C, and 0.05-0.5 parts of dopamine hydrochloride, 0.05-0.5 parts of catechol, and 0.05-0.5 parts of tannic acid are added to the solution every 4-8 hours, and ultrasonically treated after mixing, nitrogen is passed through to deoxygenate, and the temperature of the mixed solution is maintained at 20-25°C. After 24-36 hours, a mixed solution of a self-polymerized high molecular polymer is obtained and used immediately.

[0017] In some embodiments of the present invention, the pH regulator in the repair agent A and the repair agent B is a sodium hydroxide solution.

[0018] In some embodiments of the present invention, the concentration of the tris(hydroxymethyl)aminomethane hydrochloride solution is 0.1-2 mol / L.

[0019] The second object of the present invention is to provide a method for in-situ repair of a reverse osmosis membrane, using the reverse osmosis membrane in-situ repair reagent to perform in-situ repair of the reverse osmosis membrane, the repair method:

[0020] 1) Filter the reverse osmosis membrane after acid and alkali cleaning with repair agent A, and then wash it with deionized water;

[0021] 2) Filter the reverse osmosis membrane obtained in step 1) with repair agent B, and then wash it with deionized water;

[0022] 3) Repeat steps 1) and 2) for 3 to 5 times, and then soak the reverse osmosis membrane in repair reagent B;

[0023] 4) Clean the reverse osmosis membrane repaired in step 3) with deionized water.

[0024] In some embodiments of the present invention, the specific steps of repairing include the following steps:

[0025] 1) Filter the reverse osmosis membrane after acid and alkali cleaning with repair agent A at a pressure of 3 to 15 bar for 3 to 10 minutes at a filtration temperature of 20 to 25°C, and then wash with deionized water for 5 to 10 minutes;

[0026] 2) Filter the reverse osmosis membrane obtained in step 1) with repair agent B at a pressure of 3 to 15 bar for 3 to 10 minutes at a filtration temperature of 20 to 25°C, and then wash with deionized water for 5 to 10 minutes;

[0027] 3) Repeat steps 1) and 2) for 3 to 5 times, and then soak the reverse osmosis membrane in the repair reagent B for 12 to 24 hours at a soaking temperature of 20 to 30°C;

[0028] 4) Clean the reverse osmosis membrane repaired in step 3) with deionized water, and the cleaning time is not less than 30 minutes.

[0029] In some embodiments of the present invention, the acid-base cleaning process is carried out using an acidic cleaning solution and / or an alkaline cleaning solution, the acidic cleaning solution is one or more of hydrochloric acid, citric acid solution or oxalic acid solution, and the alkaline cleaning solution is a sodium hydroxide solution.

[0030] In some embodiments of the present invention, in step 1), the desalination rate of the reverse osmosis membrane is 60-90%. The above-mentioned reverse osmosis membrane repair agent of the present invention is used to repair the degraded reverse osmosis membrane with different desalination rates, so that the desalination rate of the reverse osmosis membrane is restored to a level close to the desalination rate of the original membrane.

[0031] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0032] The present invention provides a simple, easily available and low-cost reverse osmosis membrane repair agent A and repair agent B to restore the desalination rate of the membrane. The method can restore the desalination rate of a deteriorated reverse osmosis membrane of 60-90% to more than 95% in situ, and the membrane water production flux is maintained at a high level.

[0033] The repair method of the present invention does not need to be adjusted and implemented according to the desalination rate of the reverse osmosis membrane, and the repair method has excellent repair effects on reverse osmosis membranes with different desalination rates.

[0034] In the repair method of the present invention, the repair agent A and the repair agent B are used sequentially. After the repair agent A repairs the reverse osmosis membrane, it continues to react under the action of the repair agent B, synergizes physical and chemical effects, fills the membrane pores with small molecules, and enhances the membrane repair effect through self-polymerization reaction after filling. Dopamine hydrochloride, catechol, tannic acid, etc. after the self-polymerization reaction are first filled in the membrane pores of different sizes through physical action, and then under the action of trishydroxymethylaminomethane hydrochloride solution, the polymerization reaction is accelerated to further fill the membrane pores, making the repair effect more stable. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0036] Embodiment 1:

[0037] This embodiment provides a reagent and method for simulating in-situ repair of a deteriorated reverse osmosis membrane, comprising the following steps:

[0038] 1. Preparation of a mixed solution of a self-polymerizing polymer:

[0039] First, 0.5 parts of dopamine hydrochloride, 0.5 parts of catechol, 0.5 parts of tannic acid and 100 parts of deionized water were prepared into an initial mixed solution, ultrasonically treated, deoxygenated by nitrogen, the temperature of the mixed solution was maintained at 25°C, magnetic stirring was performed, and nitrogen was continued to be deoxygenated. Then the solution was allowed to stand at 25°C, and 0.5 parts of dopamine hydrochloride, 0.5 parts of catechol, and 0.5 parts of tannic acid were added to the solution every 4 hours, ultrasonically treated after mixing, deoxygenated by nitrogen, and the temperature of the mixed solution was maintained at 25°C. After 36 hours, a mixed solution of a self-polymerized high molecular polymer was obtained and used immediately.

[0040] 2. Preparation of repair agent:

[0041] 1. Preparation of repair agent A:

[0042] The prepared self-polymerizing polymer mixed solution is mixed with deionized water, wherein the self-polymerizing polymer mixed solution is 50 parts and deionized water is 50 parts, and the pH value is adjusted to 8.0 with sodium hydroxide solution for standby use.

[0043] 2. Preparation of repair agent B:

[0044] 0.5 parts of 1 mol / L tris(hydroxymethyl)aminomethane hydrochloride) solution and 99.5 parts of deionized water were mixed, and the pH value was adjusted to 9.0 with sodium hydroxide solution.

[0045] 3. The method of using the above reverse osmosis membrane repair agent in membrane repair comprises the following steps:

[0046] 1) The unused reverse osmosis membranes were soaked in 1000 ppm alkaline sodium hypochlorite solution at 25 °C. The soaking time of groups 1 to 4 was 2, 4, 6, and 8 h, respectively. After soaking, they were washed with deionized water for 5 min and then soaked in 1000 ppm acidic sodium hypochlorite solution at 25 °C for 2 h to simulate the deterioration of reverse osmosis membranes.

[0047] 2) Filter the simulated deteriorated reverse osmosis membrane with the repair agent A solution at an operating pressure of 15 bar for 10 min and a filtration temperature of 25°C, and then rinse with deionized water for 10 min;

[0048] 3) After the repair agent A is filtered, the reverse osmosis membrane is filtered with the repair agent B solution at an operating pressure of 15 bar for 10 minutes and a filtration temperature of 25°C. After filtration, it is washed with deionized water for 10 minutes;

[0049] 4) Repeat steps 1) and 2) for 5 times, and then soak the reverse osmosis membrane in repair reagent B for 24 h at a soaking temperature of 30°C.

[0050] 4. The comparison of the above reverse osmosis membrane repair agent in the membrane repair method includes the following steps:

[0051] 1) The unused reverse osmosis membranes were soaked in 1000 ppm alkaline sodium hypochlorite solution at 25 °C. The soaking time of groups 1 to 4 was 2, 4, 6, and 8 h, respectively. After soaking, they were washed with deionized water for 5 min and then soaked in 1000 ppm acidic sodium hypochlorite solution at 25 °C for 2 h to simulate the deterioration of reverse osmosis membranes.

[0052] 2) The simulated deteriorated reverse osmosis membranes were divided into two groups, and the repair agent A and B solutions were filtered at an operating pressure of 15 bar for 10 min and a filtration temperature of 25°C. After filtration, they were washed with deionized water for 10 min;

[0053] 3) Repeat step 2) for 5 times, and then soak the reverse osmosis membrane in repair reagent B for 24 h at a soaking temperature of 30°C.

[0054] Performance Test:

[0055] The performance of the reverse osmosis membrane before repair in this example (ie, the deteriorated reverse osmosis membrane) and the reverse osmosis membrane after repair by the method of the present invention were tested, and the main performance parameters were the salt rejection rate (R) and the water flux (F).

[0056] The operating conditions used for the reverse osmosis composite membrane performance test are: the inlet water is a sodium chloride aqueous solution with a salt content of 2000 ppm, the operating pressure is 10 bar, and the operating temperature is 20°C. The performance tests of 4 groups of deteriorated reverse osmosis membranes and repaired membranes are shown in Table 1.

[0057] Table 1 Reverse osmosis membrane performance test results after repair in Example 1:

[0058]

[0059] Embodiment 2:

[0060] This embodiment provides a reagent and method for in-situ repair of a deteriorated reverse osmosis membrane, comprising the following steps:

[0061] 1. Preparation of self-polymerizing polymer mixed solution:

[0062] First, 0.5 parts of dopamine hydrochloride, 0.5 parts of catechol, 0.5 parts of tannic acid and 100 parts of deionized water were prepared into an initial mixed solution, ultrasonically treated, deoxygenated by nitrogen, and the temperature of the mixed solution was maintained at 25°C. Magnetic stirring was performed, and nitrogen was continued to be deoxygenated. The solution was then allowed to stand at 25°C, and 0.5 parts of dopamine hydrochloride, 0.5 parts of catechol, and 0.5 parts of tannic acid were added to the solution every 4 hours, and ultrasonically treated after mixing, deoxygenated by nitrogen, and the temperature of the mixed solution was maintained at 25°C. After 36 hours, a mixed solution of a self-polymerized high molecular polymer was obtained and used immediately.

[0063] 2. Preparation of repair agent:

[0064] 1. Preparation of repair agent A:

[0065] The prepared mixed solution of self-polymerizing polymer is mixed with deionized water, wherein the mixed solution of self-polymerizing polymer is 50 parts and the deionized water is 50 parts, and the pH value is adjusted to 8.0 with sodium hydroxide solution.

[0066] 2. Preparation of repair agent B:

[0067] Add 0.5 parts of 1 mol / L tris(hydroxymethyl)aminomethane hydrochloride solution and 99.5 parts of deionized water, and adjust the pH value to 9.0 with sodium hydroxide solution.

[0068] 3. The method of using the above reverse osmosis membrane repair agent in membrane repair comprises the following steps:

[0069] 1) Pre-clean the reverse osmosis membrane. The pre-cleaning is conventional cleaning, using citric acid acid cleaning agent and sodium hydroxide alkaline cleaning agent for cleaning.

[0070] 2) Filter the cleaned reverse osmosis membrane with repair agent A solution at an operating pressure of 15 bar for 10 min and a filtration temperature of 25°C. After filtration, rinse with deionized water for 10 min;

[0071] 3) After the repair agent A is filtered, the reverse osmosis membrane is filtered with the repair agent B solution at an operating pressure of 15 bar for 10 minutes and a filtration temperature of 25°C. After filtration, it is washed with deionized water for 10 minutes;

[0072] 4) Repeat steps 1) and 2) for 3 times, and then soak the reverse osmosis membrane in repair reagent B for 24 h at a soaking temperature of 30°C.

[0073] 4. The comparison of the above reverse osmosis membrane repair agent in membrane repair includes the following steps:

[0074] 1) Pre-clean the reverse osmosis membrane. The pre-cleaning is conventional cleaning, using citric acid acid cleaning agent and sodium hydroxide alkaline cleaning agent for cleaning.

[0075] 2) The cleaned reverse osmosis membrane was filtered with repair agent A and B solution at an operating pressure of 15 bar for 10 min and a filtration temperature of 25°C. After filtration, it was washed with deionized water for 10 min;

[0076] 3) Repeat step 2) for 3 times, and then soak the reverse osmosis membrane in repair reagent B for 24 h at a soaking temperature of 30°C.

[0077] Performance Test:

[0078] The performance of the reverse osmosis membrane before repair in this embodiment and the reverse osmosis membrane after repair according to the method of this embodiment were tested, and the main performance parameters were the salt rejection rate (R) and the water flux (F).

[0079] The operating conditions used for the reverse osmosis membrane performance test are: the influent is a sodium chloride aqueous solution with a salt content of 2000 ppm, the operating pressure is 10 bar, and the operating temperature is 20°C. The performance tests were conducted on two groups of reverse osmosis membranes after conventional cleaning and the repaired membranes, as shown in Table 2.

[0080] Table 2 Test results of membrane performance after repair in Example 2:

[0081]

[0082] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for in-situ repair of a reverse osmosis membrane, characterized in that: The reverse osmosis membrane is repaired in situ by using a reverse osmosis membrane in situ repair reagent; the reverse osmosis membrane in situ repair reagent comprises a repair agent A and a repair agent B, wherein the repair agent A comprises, by weight, 50 to 80 parts of a mixed solution of a self-polymerizing high molecular polymer and 20 to 50 parts of deionized water, with a pH value of 7.0 to 8.5; The composition of the repair agent B is: 0.5-5 parts of tris(hydroxymethyl)aminomethane hydrochloride solution, 95-99.5 parts of deionized water, and the pH value is 8.5-10.0; the mixed solution of the self-polymerizing high molecular polymer is prepared by the following method: S1. Prepare a mixed solution of dopamine hydrochloride, catechol and tannic acid with deionized water, perform ultrasonic treatment, pass inert gas to deoxygenate and continue stirring; S2, allowing the mixed solution obtained in step S1 to stand after deoxygenation and stirring, and adding dopamine hydrochloride, catechol and tannic acid to the mixed solution every 4 to 8 hours, mixing, ultrasonically treating, passing an inactive gas to remove oxygen, and maintaining a constant temperature to obtain the mixed solution of the self-polymerizing high molecular polymer; In step S1, the amount of dopamine hydrochloride is 0.05-0.5 parts, the amount of catechol is 0.05-0.5 parts, the amount of tannic acid is 0.05-0.5 parts and the amount of deionized water is 100 parts; In step S2, the amount of dopamine hydrochloride is 0.05-0.5 parts, the amount of catechol is 0.05-0.5 parts, and the amount of tannic acid is 0.05-0.5 parts; The reverse osmosis membrane in-situ repair method includes the following steps: 1) Filter the reverse osmosis membrane after acid and alkali cleaning with repair agent A, and then wash it with deionized water; 2) Filter the reverse osmosis membrane obtained in step 1) with repair agent B, and then wash it with deionized water; 3) Repeat steps 1) and 2) for 3 to 5 times, and then soak the reverse osmosis membrane in repair reagent B; 4) Clean the reverse osmosis membrane repaired in step 3) with deionized water.

2. The reverse osmosis membrane in-situ repair method according to claim 1, characterized in that: In step S2, the standing temperature of the mixed solution is 20-25°C; The constant temperature is 20-25°C, and the constant temperature time is 24-36 hours.

3. The method for in-situ repair of reverse osmosis membrane according to claim 1, characterized in that: The concentration of the tris(hydroxymethyl)aminomethane hydrochloride) solution is 0.1-2 mol / L.

4. The method for in-situ repair of reverse osmosis membrane according to claim 1, characterized in that: The acid-base cleaning process is carried out using an acid cleaning solution and / or an alkaline cleaning solution. The acid cleaning solution is one or more of hydrochloric acid, citric acid solution or oxalic acid solution, and the alkaline cleaning solution is a sodium hydroxide solution.

5. The method for in-situ repair of reverse osmosis membrane according to claim 1, characterized in that: In step 1), the desalination rate of the reverse osmosis membrane is 60-90%.

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