Method for removing organic micropollutants from water and use thereof

Abstract

The present application relates to a kind of methods for removing organic micro-pollutants in water and its application, belong to water treatment technical field.The method for removing organic micro-pollutants in water provided by the present application includes the following steps: (1) the pH of the aqueous solution containing organic micro-pollutants is adjusted to be acidic, to obtain a mixture; (2) adding oxidizing agent to the mixture obtained in step (1), and reacting at-20 to-40 DEG C.The method removes organic micro-pollutants at a fast rate, with high removal efficiency, and can utilize the freeze-thaw cycle in the natural environment to degrade pollutants, with low energy consumption, low operating cost, and little interference from water quality background substances.If applied to the cold chain disinfection process, it is of great significance to the degradation of organic pollutants and the disinfection of microorganisms.The method is simple to operate, does not require excessive addition of chemical reagents, is less affected by background ions, and has natural application scenarios, making it an economical, efficient and green method of enhanced oxidation.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for removing organic micropollutants from water and its application. Background Technology

[0002] In industrial water treatment, highly efficient oxidants are commonly used to oxidize wastewater. Hypochlorous acid (HOCl), sodium hypochlorite (NaClO), and potassium permanganate (KMnO4) are among the most frequently used oxidants. HOCl / NaClO can kill bacteria, viruses, and parasites in water. Its disinfection mechanism is similar to chlorine (Cl2), destroying the protein structure of microorganisms through oxidation, thereby achieving disinfection. HOCl / NaClO also has a coagulation-aiding effect, assisting in the removal of colored substances and algae from water through coagulation and sedimentation. Furthermore, they can oxidize organic matter and harmful substances such as color, thus improving the color of the water. KMnO4 can remove trace organic pollutants from water, reduce color / odor, and inhibit algae growth. This technology exhibits good selectivity, and the oxidation process does not produce halogenated byproducts. In summary, highly efficient oxidants play multiple roles in water treatment, including disinfection, oxidation, sedimentation, deodorization, and inhibition of biofouling, playing a vital role in improving water quality, protecting equipment, and maintaining the environment.

[0003] However, HOCl / NaClO and KMnO4 are both selective oxidants, effectively removing organic matter with electron-rich groups (such as phenols) from water, but with extremely limited removal of some common organic micropollutants (such as carbamazepine and ibuprofen). To improve the oxidizing capacity of oxidants, a series of enhanced oxidant oxidation processes have been developed. These include catalytic oxidation by introducing activated carbon and heavy metals, but these operations complicate the water treatment process; furthermore, the introduction of additional chemicals poses a risk of secondary pollution and increases the cost of the water treatment process. Processes based on light (ultraviolet and visible light) to enhance oxidant oxidation can significantly improve oxidation capacity, but UV radiation can have adverse effects on the human body, causing health problems; simultaneously, the light irradiation process is greatly affected by background substances in the water.

[0004] Therefore, there is a need to find a green, healthy, and efficient water pollution treatment method that does not require the introduction of other substances, effectively reduces treatment costs, minimizes interference from background substances in the water, and does not pose a threat to human health. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and to provide a method for removing organic micropollutants from water and its application.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a method for removing organic micropollutants from water, comprising the following steps:

[0008] (1) Adjust the pH of the aqueous solution containing organic micro-pollutants to acidic to obtain a mixed solution;

[0009] (2) Add an oxidant to the mixture obtained in step (1) and react at -20℃ to -40℃.

[0010] This invention provides a novel method for removing organic micropollutants based on cryogenic treatment at -20℃ to -40℃. Compared to conventional oxidant treatment of organic micropollutants, this invention leverages the freeze-thaw concentration effect. By freezing the test reaction solution containing the oxidant, a highly concentrated salt solution is obtained in the frozen liquid lattice, enhancing the efficiency of the oxidant in degrading organic micropollutants. This method removes organic micropollutants rapidly and efficiently, and can utilize the freeze-thaw cycle in the natural environment for pollutant degradation. It is energy-efficient, has low operating costs, and is minimally affected by background water quality. When applied to cold chain disinfection processes, it is significant for the degradation of organic pollutants and the elimination of microorganisms. Furthermore, this method is simple to operate, requires minimal chemical reagent addition, is less affected by background ion interference, and has natural application scenarios, making it an economical, efficient, and green method for enhanced oxidation.

[0011] Preferably, in step (1), the organic micropollutant includes at least one of carbamazepine (CBZ), ibuprofen (IBP), cinnamic acid (CA), and sorbic acid (SA).

[0012] More preferably, in step (1), the organic micropollutant is at least one of carbamazepine, cinnamic acid, and sorbic acid.

[0013] The method of this invention has a rapid and efficient removal effect on organic micro-pollutants such as carbamazepine, ibuprofen, cinnamic acid, and sorbic acid, and has a particularly superior removal effect on carbamazepine, cinnamic acid, and sorbic acid.

[0014] Preferably, in step (1), the pH of the mixture does not exceed 6.5; further, the pH of the mixture does not exceed 5; and even further, the pH of the mixture is 4-5.

[0015] The method of the present invention has excellent removal effect under acidic conditions.

[0016] Preferably, in step (1), the pH is adjusted by adding a buffer solution to the aqueous solution containing organic micropollutants.

[0017] Preferably, in step (1), the concentration of the organic micropollutants in the mixture is 1 μmol / L-3 μmol / L.

[0018] Preferably, in step (2), the oxidant includes at least one of hypochlorous acid (HOCl), sodium hypochlorite (NaClO), and potassium permanganate (KMnO4).

[0019] Preferably, in step (2), the concentration of the oxidant in the solution system is 30 μmol / L-50 μmol / L.

[0020] Preferably, in step (2), the reaction temperature is -20℃ to -25℃.

[0021] Preferably, in step (2), a soluble salt is added to the mixture obtained in step (1), wherein the soluble salt includes at least one of chloride, sulfate and nitrate.

[0022] This invention, through research, has discovered that during the freezing treatment of the test reaction solution containing oxidant, common inorganic anions in water, such as chloride, sulfate, and nitrate ions, can further enhance the removal of organic micropollutants by the oxidant, thus further promoting the removal of organic micropollutants. Specifically, step (2) involves adding an oxidant and a soluble salt to the mixture obtained in step (1) and reacting at -20℃ to -40℃.

[0023] Optionally, the soluble salt includes at least one of sodium chloride, sodium sulfate, and sodium nitrate.

[0024] More preferably, the soluble salt includes at least one of chloride and nitrate.

[0025] This invention discovers through research that Cl - and NO3 - It has a superior promoting effect on the removal of organic micropollutants.

[0026] Preferably, in step (2), the concentration of the anion in the soluble salt in the solution system is not less than 0.05 mmol / L; further, the concentration of the anion in the soluble salt in the solution system is not less than 1 mmol / L; optionally, the concentration of the anion in the soluble salt in the solution system is 1 mmol / L-5 mmol / L.

[0027] Increasing the concentration of inorganic anions has a further positive promoting effect on the removal of organic micropollutants. The concentration of anions is preferably not less than 0.05 mM, and more preferably not less than 1 mM.

[0028] Secondly, the present invention provides the application of the method for removing organic micropollutants from water in water treatment.

[0029] The present invention has the following beneficial effects:

[0030] This invention enhances the ability of oxidants such as HOCl / NaClO / KMnO4 to degrade typical pharmaceutical-grade organic micropollutants CBZ, IBP, CA, and SA through a freezing treatment method at -20℃ to -40℃. Furthermore, this invention also discovers common inorganic anions in water, such as Cl... - NO3 - It has a significant promoting effect on the reaction. Furthermore, it was found that increasing the concentration of inorganic anions and decreasing the freezing temperature promote the reaction. The method of this invention is simple and easy to operate, requiring no excessive addition of carbon, heavy metals, or other chemical reagents, and poses no health hazards to users. It is an economical, efficient, and green technology for enhancing the oxidation and hydrolysis capabilities of oxidants, and has excellent effects on removing organic micropollutants from water. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the principle of the method for removing organic micropollutants from water according to the present invention. Detailed Implementation

[0032] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0033] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0034] Example 1

[0035] A method for removing organic micropollutants from water includes the following steps:

[0036] (1) Add the aqueous solution of CBZ to a glass container containing a certain buffer solution (pH = 4.0, 5 mmol / L acetic acid) to obtain a mixture; the concentration of CBZ in the mixture is 2 μmol / L;

[0037] (2) Add oxidant HOCl to the mixture obtained in step (1) so that the concentration of HOCl in the solution is 40 μmol / L, and let it stand at -25℃ for reaction.

[0038] A schematic diagram illustrating the principle of the method for removing organic micropollutants from water according to the present invention is shown below. Figure 1 As shown.

[0039] Water samples were taken after different minutes of reaction. The reaction was terminated by capturing the remaining HOCl with excess sodium thiosulfate solution. The concentration of the remaining CBZ in the solution was determined by high performance liquid chromatography, and the removal rate of CBZ was calculated. The removal rate was 56.21% after 5 minutes, 94.7% after 10 minutes, and 96.75% after 150 minutes.

[0040] Example 2

[0041] A method for removing organic micropollutants from water includes the following steps:

[0042] (1) Add the aqueous solution of CBZ to a glass container containing a certain buffer solution (pH = 4.0, 5 mmol / L acetic acid) to obtain a mixture; the concentration of CBZ in the mixture is 2 μmol / L;

[0043] (2) Add NaCl solution to the mixture obtained in step (1) so that the Cl in the mixture is concentrated. - The concentration was 0.1 mmol / L, and then the oxidant HOCl was added to make the concentration of HOCl in the solution 40 μmol / L. The reaction was allowed to stand at -25℃.

[0044] Water samples were taken after different minutes of reaction. The reaction was terminated by capturing the remaining HOCl with excess sodium thiosulfate solution. The concentration of the remaining CBZ in the solution was determined by high performance liquid chromatography, and the removal rate of CBZ was calculated. The removal rate was 68.89% after 5 minutes and 98.5% after 10 minutes.

[0045] Example 3

[0046] The difference between this embodiment and Embodiment 2 is that, in step (2), the Cl in the mixture... - The concentration was 1 mmol / L, and all other parameters were the same as in Example 2. In this example, the removal rate was 93.42% after 5 minutes and 99.88% after 10 minutes.

[0047] Example 4

[0048] The difference between this embodiment and Example 1 is that in step (1), the pH of the buffer solution is 5.0, while the rest are the same as in Example 1. In this embodiment, the removal rate was 17.1% after 5 minutes, 93.25% after 10 minutes, and 98.02% after 150 minutes.

[0049] Example 5

[0050] The difference between this embodiment and Embodiment 2 is that in step (1), the pH of the buffer solution is 5.0, while the rest are the same as in Embodiment 2. In this embodiment, the removal rate is 27.47% after 5 minutes, 93.83% after 10 minutes, and 96.64% after 150 minutes.

[0051] Example 6

[0052] The difference between this embodiment and Embodiment 3 is that in step (1), the pH of the buffer solution is 5.0, while the rest are the same as in Embodiment 3. In this embodiment, the removal rate was 29.43% after 5 minutes and 97.96% after 10 minutes.

[0053] Example 7

[0054] The difference between this embodiment and Example 1 is that in step (1), the pH of the buffer solution is 6.5 (5 mmol / L sodium dihydrogen phosphate), while the rest are the same as in Example 1. In this embodiment, the removal rate was 17.34% after 5 minutes, 89.05% after 10 minutes, and 96.29% after 150 minutes.

[0055] Example 8

[0056] The difference between this embodiment and Example 2 is that in step (1), the pH of the buffer solution is 6.5 (5 mmol / L sodium dihydrogen phosphate), while the rest are the same as in Example 2. In this embodiment, the removal rate was 23.87% after 5 minutes, 91.2% after 10 minutes, and 98.38% after 150 minutes.

[0057] Example 9

[0058] The difference between this embodiment and Example 3 is that in step (1), the pH of the buffer solution is 6.5 (5 mmol / L sodium dihydrogen phosphate), while the rest are the same as in Example 3. In this embodiment, the removal rate is 26.81% after 5 minutes, 92.85% after 10 minutes, and 98.05% after 150 minutes.

[0059] Example 10

[0060] A method for removing organic micropollutants from water includes the following steps:

[0061] (1) Add an aqueous solution of IBP to a glass container containing a certain amount of buffer solution (pH = 6.5, 5 mmol / L sodium dihydrogen phosphate) to obtain a mixture; the concentration of IBP in the mixture is 2 μmol / L.

[0062] (2) Add oxidant HOCl to the mixture obtained in step (1) so that the concentration of HOCl in the solution is 40 μmol / L, and let it stand at -25℃ for reaction.

[0063] After 180 min of reaction, water samples were taken, and the reaction was terminated by capturing the remaining HOCl with excess sodium thiosulfate solution. The concentration of the remaining IBP in the solution was determined by high performance liquid chromatography, and the removal rate of IBP was calculated. After 180 min, the removal rate was 20.24%.

[0064] Example 11

[0065] A method for removing organic micropollutants from water includes the following steps:

[0066] (1) Add an aqueous solution of IBP to a glass container containing a certain amount of buffer solution (pH = 6.5, 5 mmol / L sodium dihydrogen phosphate) to obtain a mixture; the concentration of IBP in the mixture is 2 μmol / L.

[0067] (2) Add NaCl solution to the mixture obtained in step (1) so that the Cl in the mixture is concentrated. - The concentration was 0.1 mmol / L, and then the oxidant HOCl was added to make the concentration of HOCl in the solution 40 μmol / L. The reaction was allowed to stand at -25℃.

[0068] After 180 min of reaction, water samples were taken, and the reaction was terminated by capturing the remaining HOCl with excess sodium thiosulfate solution. The concentration of the remaining IBP in the solution was determined by high performance liquid chromatography, and the removal rate of IBP was calculated. After 180 min, the removal rate was 28.28%.

[0069] Example 12

[0070] The difference between this embodiment and Embodiment 11 is that, in step (2), the Cl in the mixture... - The concentration was 1 mmol / L, and all other parameters were the same as in Example 11. In this example, the removal rate was 36.14% after 180 min.

[0071] Example 13

[0072] The difference between this embodiment and Embodiment 1 is that in step (2), the oxidant is NaOCl instead of HOCl; the rest of the methods are the same as in Embodiment 1. In this embodiment, the removal rate after 10 minutes was 89.05%.

[0073] Example 14

[0074] The difference between this embodiment and Example 1 is that in step (2), the oxidant is KMnO4 instead of HOCl; the rest of the methods are the same as in Example 1. After reacting for 10 minutes, a water sample was taken, and the reaction was terminated by capturing the remaining KMnO4 with ascorbic acid solution. The concentration of the remaining CBZ in the solution was determined by high performance liquid chromatography. In this embodiment, the removal rate after 10 minutes was 98.25%.

[0075] Example 15

[0076] The difference between this embodiment and Embodiment 7 is that in step (1), the organic micro-pollutant is CA instead of CBZ; the rest of the methods are the same as in Embodiment 7. In this embodiment, the removal rate after 10 minutes is 98.57%.

[0077] Example 16

[0078] The difference between this embodiment and Embodiment 7 is that in step (1), the organic micro-pollutant is SA, not CBZ; the rest of the methods are the same as in Embodiment 7. In this embodiment, the removal rate is 99.95% after 10 minutes and 100% after 120 minutes.

[0079] Example 17

[0080] The difference between this embodiment and Embodiment 7 is that in step (2), the reaction temperature is -20℃ instead of -25℃; the rest of the methods are the same as in Embodiment 7. In this embodiment, the removal rate after 10 minutes is 89.05%.

[0081] Example 18

[0082] The difference between this embodiment and embodiment 8 is that, in step (2), the Cl in the mixture... - The concentration was 5 mmol / L, and the rest of the methods were the same as in Example 8. In this example, the removal rate was 98.25% after 10 minutes.

[0083] Example 19

[0084] The difference between this embodiment and embodiment 9 is that, in step (2), Na2SO4 solution is added to the mixture obtained in step (1), so that the SO4 content in the mixture is reduced. 2- The concentration was 1 mmol / L, without the addition of NaCl solution; all other methods were the same as in Example 9. In this example, the removal rate was 90.65% after 10 minutes.

[0085] Example 20

[0086] The difference between this embodiment and embodiment 9 is that, in step (2), NaNO3 solution is added to the mixture obtained in step (1), so that the NO3 in the mixture... -The concentration was 1 mmol / L, without the addition of NaCl solution; all other methods were the same as in Example 9. In this example, the removal rate was 95.30% after 10 minutes.

[0087] Comparative Example 1

[0088] The difference between this comparative method and Example 1 is that in step (1), the pH of the buffer solution is 8 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 1. The removal rate of this comparative method was 17.72% after 5 minutes and 69.06% after 10 minutes.

[0089] Comparative Example 2

[0090] The difference between this comparative method and Example 1 is that in step (1), the pH of the buffer solution is 9 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 1. The removal rate in this comparative example was 1.78% after 5 min, 32.64% after 10 min, and 64.15% after 150 min.

[0091] Comparative Example 3

[0092] The difference between this comparative example and Example 2 is that in step (1), the pH of the buffer solution is 9 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 2. The removal rate of this comparative example was 0.90% after 5 min, 38.21% after 10 min, and 65.62% after 150 min.

[0093] Comparative Example 4

[0094] The difference between this comparative example and Example 3 is that in step (1), the pH of the buffer solution is 9 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 3. The removal rate of this comparative example was 15.31% after 5 minutes and 49.41% after 10 minutes.

[0095] Comparative Example 5

[0096] The difference between this comparative method and Example 1 is that in step (1), the pH of the buffer solution is 10 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 1. The removal rate in this comparative example was 0% after 5 min, 0% after 10 min, and 12.39% after 150 min.

[0097] Comparative Example 6

[0098] The difference between this comparative example and Example 2 is that in step (1), the pH of the buffer solution is 10 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 2. The removal rate of this comparative example was 11.39% after 5 min, 13.65% after 10 min, and 15.92% after 150 min.

[0099] Comparative Example 7

[0100] The difference between this comparative example and Example 3 is that in step (1), the pH of the buffer solution is 10 (5 mmol / L sodium tetraborate), while the rest are the same as in Example 3. The removal rate of this comparative example was 0.88% after 5 min, 5.30% after 10 min, and 22.98% after 150 min.

[0101] Comparative Example 8

[0102] The difference between this comparative method and Example 1 is that in step (2), the reaction temperature is 22°C instead of -25°C, and the reaction is allowed to stand. All other steps are the same as in Example 1. The removal rate in this comparative example was 51.89% after 150 minutes.

[0103] Comparative Example 9

[0104] The difference between this comparative method and Example 2 is that in step (2), the reaction temperature is 22°C instead of -25°C, and the reaction is allowed to proceed statically; otherwise, it is the same as in Example 2. The removal rate of this comparative method was 83.59% after 150 minutes.

[0105] Comparative Example 10

[0106] The difference between this comparative method and Example 3 is that in step (2), the reaction temperature is 22℃ instead of -25℃, and the reaction is allowed to stand. All other steps are the same as in Example 3. The removal rate of this comparative method was 94.72% after 150 minutes.

[0107] Comparative Example 11

[0108] The difference between this comparative method and Example 10 is that in step (2), the reaction temperature is 20°C instead of -25°C; the rest of the methods are the same as in Example 10. The removal rate of this comparative example was 0% after 1440 min.

[0109] Comparative Example 12

[0110] The difference between this comparative method and Example 13 is that in step (2), the reaction temperature is 22°C instead of -25°C; the rest of the methods are the same as in Example 13. The removal rate of this comparative example after 10 minutes was 2.47%.

[0111] Comparative Example 13

[0112] The difference between this comparative method and Example 14 is that in step (2), the reaction temperature is 22°C instead of -25°C; the rest of the methods are the same as in Example 14. The removal rate of this comparative example was 86.3% after 10 minutes.

[0113] Comparative Example 14

[0114] The difference between this comparative method and Example 15 is that in step (2), the reaction temperature is 22°C instead of -25°C; the rest of the methods are the same as in Example 15. The removal rate of this comparative example after 120 minutes was 5.03%.

[0115] Comparative Example 15

[0116] The difference between this comparative method and Example 16 is that in step (2), the reaction temperature is 22°C instead of -25°C; the rest of the methods are the same as in Example 16. The removal rate of this comparative example after 120 minutes was 25.36%.

[0117] Comparative Example 16

[0118] The difference between this comparative example and Example 7 is that in step (2), the reaction temperature is -10℃ instead of -25℃; the rest of the methods are the same as in Example 7. The removal rate of this comparative example after 10 minutes was 27.25%.

[0119] Comparative Example 17

[0120] The difference between this comparative example and Example 7 is that in step (2), the reaction temperature is -15℃ instead of -25℃; the rest of the methods are the same as in Example 7. The removal rate of this comparative example after 10 minutes was 29.51%.

[0121] Comparative Example 18

[0122] The difference between this comparative example and Example 9 is that, in step (2), NaHCO3 solution is added to the mixture obtained in step (1), so that the HCO3 in the mixture... - The concentration was 1 mmol / L, and all other methods were the same as in Example 9. The removal rate in this comparative example was 84.80% after 10 minutes.

[0123] Comparative Example 19

[0124] The difference between this comparative example and Example 9 is that, in step (2), NaNO2 solution is added to the mixture obtained in step (1), so that the NO2 in the mixture... - The concentration was 1 mmol / L, and all other methods were the same as in Example 9. The removal rate in this comparative example was 0% after 10 minutes.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for removing organic micropollutants from water, characterized in that, Includes the following steps: (1) Adjust the pH of the aqueous solution containing organic micropollutants to acidic to obtain a mixed solution; the organic micropollutants include at least one of carbamazepine, cinnamic acid, and sorbic acid; (2) Add an oxidant to the mixture obtained in step (1) and react at -20℃ to -25℃; the oxidant includes at least one of hypochlorous acid and sodium hypochlorite; In step (2), a soluble salt, which is a chloride salt, is added to the mixture obtained in step (1). The mixture contains Cl... - The concentration is not less than 0.05 mmol / L; In step (1), the pH of the mixture does not exceed 6.

5.

2. The method for removing organic micropollutants from water according to claim 1, characterized in that, In step (1), the concentration of the organic micropollutants in the mixture is 1 μmol / L-3 μmol / L.

3. The method for removing organic micropollutants from water according to claim 1, characterized in that, In step (2), the concentration of the oxidant in the solution system is 30 μmol / L-50 μmol / L.

4. The application of the method for removing organic micropollutants from water according to any one of claims 1-3 in water treatment.

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