A reverse osmosis membrane element storage solution

Abstract

The application relates to a reverse osmosis membrane element storage solution, which comprises the following components based on the total mass of the storage solution: 5900-18000 ppm of sodium ions, 9000-30000 ppm of chlorine ions, 1-3000 ppm of multivalent cations, 2-200 ppm of ether polymers, 1-20000 ppm of non-oxidizing bactericides and a solvent; wherein the solvent comprises water; the multivalent cations comprise divalent and / or trivalent metal ions, and the ether polymers comprise structural units derived from oxirane. The reverse osmosis membrane element storage solution of an embodiment of the application can be used for the storage of reverse osmosis membrane elements; the storage of seawater desalination reverse osmosis membrane elements by using the storage solution can enable the elements to maintain stable water production, desalination rate, boron removal rate and the like after long-term storage, and can effectively control the reproduction of microorganisms.

Description

TECHNICAL FIELD

[0001] The present application relates to the preservation of reverse osmosis membrane elements, in particular to a preservation solution for reverse osmosis membrane elements used in seawater desalination. BACKGROUND

[0002] Reverse osmosis membrane technology is currently the most commonly used seawater desalination technology, and the fresh water filtered by seawater desalination reverse osmosis membrane elements is widely used in municipal water supply and industrial water. Seawater contains about 5 ppm of boron, which can affect human health. The requirement for boron content in the "Drinking Water Health Standards" (GB5749-2022) is less than 1 ppm. Therefore, the boron removal rate is an important indicator of seawater desalination reverse osmosis membrane.

[0003] The salt content in seawater is high, in order to ensure the water quality, the seawater desalination reverse osmosis membrane element is detected by standard test solution before leaving the factory, and after confirming the qualification, the wet element is preserved in the standard protection solution of 1wt% food grade sodium pyrosulfite to prevent the growth of microorganisms, and then sealed with plastic bag to isolate air.

[0004] However, after the seawater desalination reverse osmosis membrane element is preserved according to the above packaging method, the boron removal rate of the element will decrease obviously with time. Therefore, how to ensure that the wet element does not breed microorganisms while not losing the boron removal rate has become a problem to be solved. SUMMARY

[0005] To overcome at least one of the above-mentioned defects of the prior art, in a first aspect, an embodiment of the present application provides a reverse osmosis membrane element preservation solution, based on the total mass of the preservation solution, the preservation solution comprises the following components: 5900-18000ppm of sodium ions, 9000-30000ppm of chloride ions, 1-3000ppm of multivalent cations, 2-200ppm of ether polymers, 1-20000ppm of non-oxidizing bactericides and solvents.

[0006] Among them, the solvent includes water; the multivalent cation includes divalent and / or trivalent metal ions, and the ether polymer includes structural units derived from oxirane.

[0007] In a second aspect, an embodiment of the present application provides the use of the above-mentioned preservation solution in the preservation of reverse osmosis membrane elements.

[0008] In a third aspect, an embodiment of the present application provides a preservation method for reverse osmosis membrane elements, comprising soaking the reverse osmosis membrane elements in the above-mentioned preservation solution or allowing the preservation solution to soak the reverse osmosis membrane elements.

[0009] In a fourth aspect, one embodiment of the present application provides a reverse osmosis wet membrane element, comprising a reverse osmosis membrane element and the above-mentioned preservation solution infiltrating the reverse osmosis membrane element.

[0010] In a fifth aspect, one embodiment of the present application provides a reverse osmosis membrane element product, comprising a reverse osmosis wet membrane element and a packaging bag, wherein the reverse osmosis wet membrane element is located inside the packaging bag, and the reverse osmosis wet membrane element comprises a reverse osmosis membrane element and the preservation solution infiltrating the reverse osmosis membrane element.

[0011] The reverse osmosis membrane element preservation solution of one embodiment of the present application can be used for preservation of reverse osmosis membrane elements. The reverse osmosis membrane elements for seawater desalination preserved by using the preservation solution can still maintain stable water production, desalination rate, boron removal rate and the like after long-term storage, and can effectively control the reproduction of microorganisms. DETAILED DESCRIPTION

[0012] The typical embodiments embodying the features and advantages of the present application will be described in detail in the following description. It should be understood that the present application can have various changes in different embodiments, which do not deviate from the scope of the present application, and the description herein is essentially used for illustration, rather than to limit the present application.

[0013] One embodiment of the present application provides a reverse osmosis membrane element preservation solution, which comprises the following components based on the total mass of the preservation solution: 5900-18000 ppm of sodium ions, 9000-30000 ppm of chloride ions, 1-3000 ppm of multivalent cations, 2-200 ppm of ether polymers, 1-20000 ppm of non-oxidizing bactericides and solvents.

[0014] The solvents include water, the multivalent cations include divalent and / or trivalent metal ions, and the ether polymers include structural units derived from oxirane.

[0015] In one embodiment, the reverse osmosis membrane element preservation solution is an aqueous solution.

[0016] In one embodiment, the pH value of the reverse osmosis membrane element preservation solution is 3-10, for example, 3, 4, 5, 6, 7, 8, 9 or 10.

[0017] In one embodiment, the mass content of sodium ions in the preservation solution can be, for example, 5930 ppm, 5940 ppm, 6000 ppm, 7000 ppm, 8000 ppm, 10000 ppm, 12000 ppm, 12580 ppm, 12585 ppm, 12590 ppm, 13760 ppm, 13765 ppm, 14940 ppm, 14945 ppm, 15000 ppm, 17000 ppm, 17690 ppm, 17700 ppm.

[0018] In one embodiment, the mass content of chloride ions in the preservation solution can be 9000 to 30000 ppm, for example, 9160 ppm, 9170 ppm, 9190 ppm, 9200 ppm, 10000 ppm, 12000 ppm, 15000 ppm, 19000 ppm, 19410 ppm, 19420 ppm, 19430 ppm, 20000 ppm, 21530 ppm, 21540 ppm, 23080 ppm, 23090 ppm, 25000 ppm, 27300 ppm, 27310 ppm, 27410 ppm, 27420 ppm, 28000 ppm, 29590 ppm, 29600 ppm.

[0019] In one embodiment, the mass content of polyvalent cations in the preservation solution can be 1 to 3000 ppm, for example, 1 ppm, 1.5 ppm, 2 ppm, 10 ppm, 20 ppm, 21 ppm, 25 ppm, 30 ppm, 40 ppm, 43 ppm, 44 ppm, 50 ppm, 80 ppm, 100 ppm, 101 ppm, 102 ppm, 150 ppm, 200 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 2940 ppm, 2950 ppm.

[0020] In one embodiment, the mass content of ether polymers in the preservation solution can be, for example, 1 ppm, 2 ppm, 5 ppm, 10 ppm, 20 ppm, 23 ppm, 25 ppm, 30 ppm, 40 ppm, 44 ppm, 45 ppm, 50 ppm, 60 ppm, 80 ppm, 100 ppm, 120 ppm, 150 ppm, 160 ppm, 180 ppm, 190 ppm, 195 ppm, 198 ppm, 200 ppm.

[0021] In an embodiment, the mass content of the non-oxidizing bactericide in the preservation solution can be, for example, 1 ppm, 10 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, 800 ppm, 1000 ppm, 5000 ppm, 10000 ppm, 150000 ppm, 18000 ppm.

[0022] In an embodiment, the polyvalent cation comprises one, two or more of magnesium, calcium, aluminum, zinc and copper.

[0023] In an embodiment, the ether polymer comprises structural units derived from ethylene oxide, the number of which can be 4 to 12000, for example 5, 9, 10, 20, 50, 80, 100, 120, 150, 180, 200, 220, 250, 300, 500, 1000, 2000, 5000, 8000, 10000.

[0024] In an embodiment, the ether polymer comprises polyoxyethylene ether segments, for example the ether polymer can be one or more of polyethylene glycol, allyl polyethylene glycol ether, methylallyl polyethylene glycol ether, prenol polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether.

[0025] In an embodiment, the weight average molecular weight of the ether polymer is 200 to 500000, for example 300, 350, 400, 500, 800, 1000, 2000, 5000, 10000, 20000, 50000, 100000, 150000, 200000, 250000, 500000.

[0026] In an embodiment, the ether polymer can be an existing polycarboxylate superplasticizer, for example a polycarboxylate superplasticizer containing polyoxyethylene ether segments.

[0027] In an embodiment, the ether polymer can be a polycarboxylate superplasticizer containing prenol polyoxyethylene ether segments, for example a polycarboxylate superplasticizer with model number NPC-07 available from Liaoning Kelong Fine Chemical Co., Ltd.

[0028] In an embodiment, the non-oxidizing bactericide comprises 5-chloro-2-methyl-4-isothiazolin-3-one (CIT) and / or 2-methyl-4-isothiazolin-3-one (MIT).

[0029] An embodiment of the present application provides a use of the above-mentioned preservation solution in preserving a reverse osmosis membrane element.

[0030] In one embodiment, the reverse osmosis membrane element preserved by the preservation solution is a seawater desalination reverse osmosis membrane element for seawater desalination, such as the SW-8040-400-HR reverse osmosis membrane element produced by Sinochem Group Co., Ltd.

[0031] In one embodiment, the reverse osmosis membrane element preserved by the preservation solution is a wet element.

[0032] In one embodiment, the reverse osmosis membrane element is a product with a boron removal rate of greater than or equal to 85%, and the test method for the boron removal rate is the same as the test method for the boron removal rate used in the examples.

[0033] One embodiment of the present application provides a preservation method for a reverse osmosis membrane element, comprising placing (or soaking) the reverse osmosis membrane element in the preservation solution described above for preservation or allowing the preservation solution to soak the reverse osmosis membrane element for preservation.

[0034] One embodiment of the present application provides a reverse osmosis wet membrane element, comprising a reverse osmosis membrane element and the preservation solution described above soaking (or wetting) the reverse osmosis membrane element.

[0035] One embodiment of the present application provides a reverse osmosis membrane element product, comprising a reverse osmosis wet membrane element and a packaging bag, wherein the reverse osmosis wet membrane element is located inside the packaging bag, and the reverse osmosis wet membrane element comprises a reverse osmosis membrane element and a preservation solution soaking the reverse osmosis membrane element.

[0036] In one embodiment, the reverse osmosis membrane element is soaked in the preservation solution, and after being taken out, it is drained to obtain a reverse osmosis wet membrane element, which is sealed in a packaging bag for preservation.

[0037] In one embodiment, the absolute pressure inside the packaging bag is less than 30 kPa, so that the reverse osmosis membrane element (or the reverse osmosis wet membrane element) is preserved under vacuum conditions. Further, the absolute pressure inside the packaging bag can be less than 30 kPa by vacuumizing.

[0038] In one embodiment, the absolute pressure inside the packaging bag can be 10-29 kPa, such as 15 kPa, 20 kPa, 24 kPa, or 25 kPa.

[0039] In one embodiment, the packaging bag is a plastic bag, such as a PE composite packaging bag.

[0040] In one embodiment, the packaging bag is a waterproof bag.

[0041] In one embodiment, the oxygen transmission rate of the packaging bag at 23°C can be less than 100 cm 3 / m 2further can be less than 30 cm 3 / m 2 further can be less than 10 cm 3 / m 2 / day.

[0042] In one embodiment, the oxygen transmission rate of the packaging bag at 23℃ can be 10-100 cm 3 / m 2 / day, for example 20 cm 3 / m 2 / day, 30 cm 3 / m 2 / day, 50 cm 3 / m 2 / day, 60 cm 3 / m 2 / day, 80 cm 3 / m 2 / day.

[0043] The reverse osmosis membrane element storage solution of one embodiment of the present application can be used for storage of reverse osmosis membrane elements; using the storage solution to store seawater desalination reverse osmosis membrane elements can enable the elements to maintain stable water production, desalination rate, boron removal rate, etc. after long-term storage, and can effectively control the reproduction of microorganisms.

[0044] The reverse osmosis membrane element storage method of one embodiment of the present application is simple to operate, and enables the seawater desalination reverse osmosis membrane elements after long-term storage to have the advantages of stable water production, desalination rate, boron removal rate, and can avoid microbial reproduction, and has good prospects for industrialization.

[0045] Hereinafter, the reverse osmosis membrane element storage solution of one embodiment of the present application and its use are further described in combination with examples. The raw materials and test methods involved in each example and comparative example are as follows:

[0046] 1. Raw materials

[0047] The seawater desalination reverse osmosis membrane element is produced by Wanhua Chemical Group Co., Ltd., and the model is SW-8040-400-HR.

[0048] The polycarboxylate superplasticizer containing isoprenol polyoxyethylene ether segment is purchased from Liaoning Kelong Fine Chemical Co., Ltd., and the model is NPC-07.

[0049] The PE composite packaging bag is produced by Yantai Hesun Packaging Paper Co., Ltd., and includes PE-1 packaging bag, PE-2 packaging bag, and PE-3 packaging bag with different oxygen transmission rates (23℃), and the oxygen transmission rates of the three are ≤10 cm 3 / m 2 / day, ≤30 cm3 / m 2 / day, ≤100cm 3 / m 2 / sky.

[0050] 5-Chloro-2-methyl-4-isothiazolin-3-one (CIT), purchased from Huayuan Mall, brand AccuStandard, is a 100ppm standard sample aqueous solution.

[0051] Isothiazolinone, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., is composed of an aqueous solution of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT) and 2-methyl-4-isothiazolin-3-one (MIT), wherein the content of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT) is 1.825-1.925 wt%, the content of 2-methyl-4-isothiazolin-3-one (MIT) is 0.575-0.675 wt%, and the total concentration is 2.5 wt%.

[0052] 2-Methyl-4-isothiazolin-3-one (MIT), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of 95%.

[0053] All other reagents were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and are reagent-grade raw materials.

[0054] The vacuum packaging machine, model DZ, was purchased from Zhucheng Wankang Vacuum Packaging Machine Equipment Co., Ltd.

[0055] 2. Testing Methods

[0056] Testing of desalination rate, water production rate and boron removal rate

[0057] The desalination rate and permeate flow rate of a single seawater desalination reverse osmosis membrane element were tested according to the test method for desalination rate and permeate flow rate in GB / T 34241-2017 "Wound Polyamide Composite Reverse Osmosis Membrane Elements". The test solution temperature was 25℃, pH was 8.0, the test solution was a 32000ppm sodium chloride aqueous solution, the test pressure was 5.5MPa, and the element recovery rate was 8%. Boric acid was added to ensure the boron content in the test solution was 5ppm. The sodium chloride content was measured using a conductivity meter. The test methods for boron content (Cfb and Cpb) in the test solution and permeate were based on GB / T 5750.6-2006 "Standard Examination Methods for Drinking Water - Metallic Indicators". The boron removal rate was calculated using the formula (1-Cpb / Cfb)*100%.

[0058] Chloride ion content test

[0059] The chloride ion content was determined according to GB / T 15453-2018 Determination of chloride ions in industrial circulating cooling water and boiler water.

[0060] Sodium ion content test

[0061] The sodium ion content was measured according to GB / T 5750.6-2006 Standard Test Methods for Drinking Water-Metallic Elements.

[0062] Polyvalent cation content test

[0063] The polyvalent cation content was measured according to GB / T 5750.6-2006 Standard Test Methods for Drinking Water-Metallic Elements.

[0064] Plastic bag oxygen transmission rate test

[0065] The oxygen transmission rate was measured according to GB / T 19789 Test Methods for Oxygen Transmission Rate of Plastic Films and Sheeting-Coulometric Detection.

[0066] Mold quantity test in preservative solution

[0067] According to GB 4789.15-2010 National Food Safety Standard Food Microbiological Examination-Mold and Yeast Count, the preservative solution remaining in the packaging bag was collected after the packaging was opened at a certain time interval, and the mold quantity in the liquid was tested.

[0068] Examples

[0069] The bactericide, ether polymer (polyethylene glycol or polyethylene oxide or NPC-07) was added to water, then sodium chloride and polyvalent cation hydrochloride were added, and the concentrations of the components were adjusted accordingly, and hydrochloric acid or sodium hydroxide was used to adjust the pH value, to prepare the preservative solution.

[0070] Examples 1 to 7 and Comparative Examples 1 to 6 were prepared into preservative solutions with different concentrations according to the same or similar operation, and the specific concentrations are shown in Table 1.

[0071] Application examples

[0072] Five seawater desalination reverse osmosis membrane elements SW-8040-400-HR that had completed the rolling process were immersed in the preservative solution for 1 to 3 minutes, then drained for 10 minutes after being taken out, and then sealed and packaged by using PE packaging bags with vacuumizing, and stored at a constant temperature of 20°C. The membrane elements were taken out at different times (7 days, 14 days, 30 days, 90 days and 180 days) after storage, and various performance tests were performed, and the results are shown in Tables 2 and 3.

[0073] The preservative solutions of Examples 1 to 7 and Comparative Examples 1 to 6 were stored and tested according to the above steps, and the types of packaging bags used and the vacuumizing pressure are shown in Table 1.

[0074] Table 1 Composition and packaging of preservative solutions used in each example and comparative example

[0075]

[0076]

[0077] Table 2: Test results of desalination rate of membrane elements of each example and comparative example

[0078] 7 days 14 days 30 days 90 days 180 days Comparative Example 1 90.1％ 89.3％ 88.2％ 86.5％ 84.5％ Comparative Example 2 91.1％ 89.6％ 89.2％ 87.1％ 85.4％ Comparative Example 3 92.1％ 90.3％ 89.2％ 88.1％ 87.5％ Comparative Example 4 92.4％ 91.3％ 90.4％ 89.1％ 88.6％ Comparative Example 5 91.6％ 90.8％ 89.6％ 87.8％ 85.9％ Comparative Example 6 91.3％ 90.1％ 89.6％ 87.1％ 86.9％ Example 1 92.0％ 91.3％ 92.1％ 91.9％ 92.2％ Example 2 91.8％ 92.1％ 91.8％ 92.4％ 92.1％ Example 3 92.3％ 91.9％ 92.2％ 91.4％ 92.6％ Example 4 91.7％ 92.4％ 92.3％ 91.5％ 91.9％ Example 5 91.2％ 91.1％ 91.6％ 91.1％ 90.9％ Example 6 92.4％ 92.3％ 92.0％ 91.9％ 91.8％ Example 7 91.7％ 92.1％ 91.8％ 92.0％ 91.7％

[0079] Table 3: Test results of mold number of preservation solution of membrane elements of each example and comparative example

[0080]

[0081] Table 4: Test results of water production and desalination rate of membrane elements of each example and comparative example

[0082]

[0083] As shown in Tables 1 to 4, the seawater desalination reverse osmosis membrane elements of Examples 1 to 7 of the present application have a high desalination rate (more than 90%) and a mold number of less than 1 CFU / mL, and can maintain stable water production and desalination rate after being preserved for 7 days, 14 days, 30 days, 90 days and 180 days by the preservation solution containing specific components.

[0084] The Na2S2O5 preservation solution used in Comparative Example 1 is a preservation solution for preserving reverse osmosis membrane elements in the prior art. According to the results in Tables 2 and 3, the preservation solution of Comparative Example 1 can maintain the mold number at less than 1 CFU / mL, but the desalination rate of the membrane elements is significantly reduced after being preserved for 90 days and 180 days.

[0085] The preservation solutions of Comparative Examples 3 to 5 also contain sodium ions, chloride ions, multivalent cations and bactericides, but lack ether polymers compared with Examples 1 to 5. The results in Table 2 show that the desalination rate of the membrane elements preserved by Comparative Examples 3 to 5 is higher than that of Comparative Example 1, but still cannot reach more than 90%.

[0086] Unless otherwise defined, all terms used in the present application are intended to have the meanings commonly used by those skilled in the art.

[0087] The embodiments described in the present application are only for illustrative purposes, and are not intended to limit the protection scope of the present application. Those skilled in the art can make various other replacements, changes and improvements within the scope of the present application, and thus the present application is not limited to the above-described embodiments, but is only limited by the claims.

Claims

1. A preservation solution for a reverse osmosis membrane element, comprising, based on the total mass of the preservation solution, 5900 to 18000 ppm of sodium ions, 9000 to 30000 ppm of chloride ions, 1 to 3000 ppm of polyvalent cations, 2 to 200 ppm of an ether polymer, 1 to 20000 ppm of a non-oxidizing bactericide, and a solvent; wherein the solvent comprises water; the polyvalent cations comprise divalent and / or trivalent metal ions; the ether polymer comprises a structural unit derived from oxirane. wherein The polyvalent cations comprise one or more of magnesium, calcium, aluminum, zinc, and copper; and / or, 2. The preservative solution of claim 1, wherein, The number of the structural unit derived from oxirane is 4 to 12000; and / or, The pH value of the preservation solution is 3 to 10. The weight average molecular weight of the ether polymer is 200 to 500000; and / or, 3. The preservative solution of claim 1, wherein, The ether polymer comprises one or more of polyethylene glycol, allyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, prenol polyethylene glycol ether, and ethylene glycol monovinyl polyethylene glycol ether. The ether polymer comprises a polycarboxylic acid water reducer comprising a polyoxyethylene ether chain segment; and / or, 4. The preservative solution of claim 1, wherein, The non-oxidizing bactericide comprises 5-chloro-2-methyl-4-isothiazolin-3-one and / or 2-methyl-4-isothiazolin-3-one. 5.Use of the preservation solution according to any one of claims 1 to 4 for preserving a reverse osmosis membrane element. 6.The use according to claim 5, wherein the reverse osmosis membrane element is a seawater desalination reverse osmosis membrane element. 7.A method for preserving a reverse osmosis membrane element, comprising soaking the reverse osmosis membrane element in the preservation solution according to any one of claims 1 to 4 or allowing the preservation solution to infiltrate the reverse osmosis membrane element. 8.A reverse osmosis wet membrane element, comprising a reverse osmosis membrane element and the preservation solution according to any one of claims 1 to 4 infiltrating the reverse osmosis membrane element. The reverse osmosis wet membrane element is located inside the packaging bag, and the reverse osmosis wet membrane element comprises a reverse osmosis membrane element and the preservation solution according to any one of claims 1 to 4 infiltrating the reverse osmosis membrane element.

9. A reverse osmosis membrane element product comprising a reverse osmosis wet membrane element and a packaging bag, wherein, The reverse osmosis membrane element is a seawater desalination reverse osmosis membrane element; and / or, 10. The product of claim 9, wherein, The absolute pressure inside the packaging bag is less than 30 kPa; and / or, The packaging bag is a plastic bag; and / or, The packaging bag is a waterproof bag. The packaging bag has an oxygen transmission rate of less than 100 cm 3 / m 2 / day at 23°C; and / or, ​

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