Method for decomposing and mineralizing fluorine-containing organic matter wastewater

Abstract

The invention provides a method for decomposing and mineralizing fluorine-containing organic matter wastewater, which is applied to the technical field of treatment of fluorine-containing organic matter wastewater generated in a perfluoroether elastomer emulsion flocculation process, and comprises the following steps: S1, carrying out adsorption and desorption treatment on the fluorine-containing organic matter wastewater to obtain a concentrated solution of the fluorine-containing organic matter wastewater; s2, hydrogen peroxide and ferrous ions are added into a container containing the concentrated solution to obtain a mixed solution, the pH of the mixed solution is adjusted to be 2-4, the concentration mass ratio of the hydrogen peroxide to organic matter contained in the fluorine-containing organic matter wastewater is 1: 1-2, the molar ratio of the hydrogen peroxide to the ferrous ions is 1-6: 1, micro-nano bubbles are introduced into the mixed solution, and ultrasonic treatment is conducted; s3, calcium hydroxide is added into the treated mixed solution, calcium fluoride precipitates are obtained through centrifugal treatment, and the fluorine-containing organic matter in the wastewater can be degraded and mineralized.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment, specifically relating to a method for decomposing and mineralizing fluoride-containing organic wastewater. Background Technology

[0002] PFAS (perfluoroalkyl and polyfluoroalkyl substances) are a class of synthetic organic compounds with unique chemical stability and surface activity, widely used in industrial production and daily life. However, PFAS are persistent, bioaccumulative, and potentially toxic, posing a serious threat to the environment and human health. The treatment of PFAS-containing wastewater is a current challenge and a hot topic in the field of water treatment.

[0003] The fluorinated organic wastewater generated during the production of perfluoroether elastomers belongs to PFAS, but it also has its own special characteristics. This type of water contains large molecular polymers, including water-soluble or colloidal polymers with a molecular weight greater than 10,000 Daltons, as well as small molecular pollutants, including free fluorinated organics with a molecular weight less than 1,000 Daltons, small organic molecules, and one or more unpolymerized monomers.

[0004] Existing treatment methods have many shortcomings, such as incomplete treatment, easy generation of secondary pollution, and narrow applicability. Therefore, developing an efficient, environmentally friendly, and universal treatment method for fluoride-containing organic wastewater is of great practical significance.

[0005] Based on this, the present invention provides a new technical solution. Summary of the Invention

[0006] In view of this, embodiments of this specification provide a method for decomposing and mineralizing fluoride-containing organic wastewater, including... S1. The fluorine-containing organic wastewater is subjected to adsorption and desorption treatment to obtain its concentrated solution; S2. Add hydrogen peroxide and ferrous ions to the container containing the concentrated solution to obtain a mixed solution. Adjust the pH of the mixed solution to 2-4. The mass ratio of the concentration of organic matter in the hydrogen peroxide to that in the fluoride-containing organic wastewater is 1:1-2. The molar ratio of hydrogen peroxide to ferrous ions is 1-6:1. Introduce micro-nano bubbles into the mixed solution and perform ultrasonic treatment. S3. Add calcium hydroxide to the treated mixture and centrifuge to obtain calcium fluoride precipitate.

[0007] Optionally, in S1, the fluorine-containing organic wastewater is subjected to adsorption and concentration treatment via an activated carbon fiber felt adsorption bed, and the fluorine-containing organic content in the concentrate is 0.05-5 wt%.

[0008] Optionally, in S1, the adsorption bed is provided in two sets, and the two sets of adsorption beds are respectively used for adsorption and desorption treatment.

[0009] Optionally, in S1, desorption is performed by purging with superheated steam followed by cooling with clean water.

[0010] Optionally, in S1, when superheated steam is used for purging, the outlet gas is connected to a sealed cooling device. The steam condenses in the cooling device to form a vacuum, thereby creating a vacuum environment in the adsorption system and enhancing the desorption process.

[0011] Optionally, in S2, an immersion ultrasonic transducer is used for ultrasonic treatment.

[0012] Optionally, in S2, the gas in the micro-nano bubbles is oxygen, argon, nitrogen, or carbon dioxide.

[0013] Optionally, in S2, microporous aeration heads or perforated tubes are used to release micro-nano bubbles, with a gas flow rate of 0.01-2 L / min per liter of the concentrate, and the time for introducing micro-nano bubbles into the mixture and performing ultrasonic treatment is 5-60 min.

[0014] Optionally, in S3, the supernatant obtained after centrifugation of the mixture is returned to S1 for recycling.

[0015] Optionally, in S3, the calcium hydroxide is a calcium hydroxide slurry with a solid content of 10-35 wt%.

[0016] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: The technical solution of this application involves adsorption and concentration of fluoride-containing organic wastewater, specifically ferrous ions (Fe). 2+ The redox reaction between fluoride and hydrogen peroxide (H2O2) generates highly oxidizing hydroxyl radicals (·OH) to degrade organic pollutants. Ultrasonic waves generate cavitation effects, mechanical shear forces, and local high-temperature and high-pressure environments, causing microbubbles to oscillate and collapse, releasing a large amount of energy to destroy the molecular structure of pollutants or promote chemical reactions, thereby achieving the degradation and mineralization of fluoride-containing organic wastewater. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, they can also make connections based on these accompanying process diagrams without creative effort.

[0018] Figure 1 This is a process flow diagram of a method for decomposing and mineralizing fluoride-containing organic wastewater according to this application. Detailed Implementation

[0019] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0020] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and that two or more of these aspects can be combined in various ways. Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be undertaken without these specific details.

[0022] This specification provides an embodiment of a method for decomposing and mineralizing fluoride-containing organic wastewater, including: S1. The fluorine-containing organic wastewater is subjected to adsorption and desorption treatment to obtain its concentrated solution; S2. Add hydrogen peroxide and ferrous ions to the container containing the concentrated solution to obtain a mixed solution. Adjust the pH of the mixed solution to 2-4. The mass ratio of the concentration of organic matter in the hydrogen peroxide to that in the fluoride-containing organic wastewater is 1:1-2. The molar ratio of hydrogen peroxide to ferrous ions is 1-6:1. Introduce micro-nano bubbles into the mixed solution and perform ultrasonic treatment. S3. Add calcium hydroxide to the treated mixture and centrifuge to obtain calcium fluoride precipitate.

[0023] In S1, the fluorine-containing organic wastewater is treated by adsorption and concentration using an activated carbon fiber felt adsorption bed. Two sets of adsorption beds are set up, and the two sets of adsorption beds are used for adsorption and desorption treatment respectively. The fluorine-containing organic content in the concentrate is 0.05-5 wt%.

[0024] Desorption is achieved by purging with superheated steam followed by cooling with clean water. When using superheated steam purging, the outlet gas is connected to a sealed cooling device. The steam condenses inside the cooling device to create a vacuum, thus creating a vacuum environment in the adsorption system and enhancing the desorption process.

[0025] In S2, an immersion ultrasonic transducer is used for ultrasonic treatment. The gas in the micro-nano bubbles is oxygen, argon, nitrogen, or carbon dioxide.

[0026] In S2, micro-nano bubbles are released using a microporous aeration head or perforated tube. The gas flow rate corresponding to each liter of the concentrated liquid is 0.01-2 L / min. The time for introducing micro-nano bubbles into the mixture and performing ultrasonic treatment is 5-60 min.

[0027] In step S3, the supernatant obtained after centrifugation of the mixture is returned to step S1 for recycling. The calcium hydroxide is a calcium hydroxide slurry with a solid content of 10-35 wt%.

[0028] In this application, the activated carbon fiber felt adsorption bed specifically refers to ACF felt from Jiangsu Kejing Carbon Fiber Co., Ltd. The density of ACF felt is approximately 812 kg / m³. 3 The porosity of ACF is 0.58. Example 1

[0029] S1. The fluoride-containing organic wastewater has a pH of 4 and a concentration of 12 mg / L. It is treated by adsorption and concentration using an activated carbon fiber felt adsorption bed. Superheated steam is used for purging, followed by cooling with clean water for desorption. Superheated steam purging (pressure 0.2 MPa, temperature 160 ℃) is used, with the outlet gas connected to a sealed cooling device to create a vacuum, enhancing desorption and obtaining a concentrated solution with a fluoride-containing organic matter content of 780 mg / L.

[0030] S2. Place 500 mL of concentrated solution in an approximately 1000 mL ultrasonic chemical reactor. Add hydrogen peroxide and ferrous ions to the container containing the concentrated solution to obtain a mixture. The ferrous ions are ferrous sulfate. Adjust the pH of the mixture to 2.5. The mass ratio of hydrogen peroxide to fluorine-containing organic matter in the water is 1:2, and the molar ratio of hydrogen peroxide to ferrous ions is 1:1. Introduce micro-nano bubbles into the mixture and perform ultrasonic treatment using an immersion ultrasonic transducer. The ultrasonic power is 200 W, the ultrasonic frequency is 11.8 kHz, the micro-nano bubbles are oxygen, the gas flow rate is 0.1 L / min, and the treatment time is 10 min. Measure the content of fluorine-containing organic matter and calculate the decomposition rate. S3. Add calcium hydroxide to the mixture, centrifuge to obtain calcium fluoride precipitate, react the treated waste liquid with Ca(OH)2 slurry with a solid content of 15 wt% at a mass ratio of 1:0.5, adjust the pH to 7.5, centrifuge to obtain calcium fluoride precipitate, dry and weigh.

[0031] Example 2 S1. The fluoride-containing organic wastewater has a pH of 4 and a concentration of 12 mg / L. It is treated by adsorption and concentration using an activated carbon fiber felt adsorption bed. Superheated steam is used for purging, followed by cooling with clean water for desorption. Superheated steam purging (pressure 0.2 MPa, temperature 160 ℃) is used, with the outlet gas connected to a sealed cooling device to create a vacuum, enhancing desorption and obtaining a concentrated solution. The fluoride-containing organic matter content in the concentrated solution is approximately 780 mg / L.

[0032] S2. Place 500 mL of concentrated solution in an approximately 1000 mL ultrasonic chemical reactor. Add hydrogen peroxide and ferrous ions to the container containing the concentrated solution to obtain a mixture. The ferrous ions are ferrous sulfate. Adjust the pH of the mixture to 3.5. The mass ratio of the concentration of hydrogen peroxide to fluorine-containing organic matter in the water is 1:1.5, and the molar ratio of hydrogen peroxide to ferrous ions is 2:1. Introduce micro-nano bubbles into the mixture and perform ultrasonic treatment using an immersion ultrasonic transducer. The ultrasonic power is 200 W, the ultrasonic frequency is 11.8 kHz, the micro-nano bubbles are oxygen, the gas flow rate is 0.5 L / min, and the treatment time is 30 min. Measure the content and decomposition rate of fluorine-containing organic matter. S3. Add calcium hydroxide to the mixture, centrifuge to obtain calcium fluoride precipitate, react the treated waste liquid with Ca(OH)2 slurry with a solid content of 30 wt% at a mass ratio of 1:0.5, adjust the pH to 7.5, centrifuge to obtain calcium fluoride precipitate, dry and weigh.

[0033] Example 3 S1. The fluoride-containing organic wastewater has a pH of 4 and a concentration of 12 mg / L. It is treated by adsorption and concentration using an activated carbon fiber felt adsorption bed. Desorption is achieved by purging with superheated steam followed by cooling with clean water. Superheated steam purging (pressure 0.2 MPa, temperature 160 ℃) is used, with the outlet gas connected to a sealed cooling device to create a vacuum, enhancing desorption and obtaining a concentrated solution. The PFOA content in the concentrated solution is approximately 780 mg / L.

[0034] S2. Place 500 mL of the concentrated solution in an approximately 1000 mL ultrasonic chemical reactor. Add hydrogen peroxide and ferrous ions to the container containing the concentrated solution of fluorinated organic matter to obtain a mixed solution. The ferrous ions are ferrous sulfate. Adjust the pH of the mixed solution to 3.5. The mass ratio of the concentration of hydrogen peroxide to the fluorinated organic matter in the water is 1:1.5, and the molar ratio of hydrogen peroxide to ferrous ions is 6:1. Introduce micro-nano bubbles into the mixed solution and perform ultrasonic treatment using an immersion ultrasonic transducer. The ultrasonic power is 200 W, the ultrasonic frequency is 11.8 kHz, the micro-nano bubbles are oxygen, the gas flow rate is 2 L / min, and the treatment time is 60 min. Measure the content of fluorinated organic matter and calculate the decomposition rate. S3. Add calcium hydroxide to the mixture, centrifuge to obtain calcium fluoride precipitate, react the treated waste liquid with Ca(OH)2 slurry with a solid content of 30 wt% at a mass ratio of 1:0.5, adjust the pH to 7.5, centrifuge to obtain calcium fluoride precipitate, dry and weigh.

[0035] Comparative Example 1 Compared to Example 1, this embodiment omits S1, which involves placing 500 mL of wastewater into an approximately 1000 mL ultrasonic chemical reactor, with a concentration of fluorinated organic matter of 12 mg / L.

[0036] Comparative Example 2 Compared to Example 1, this embodiment omits the introduction of micro-nano bubbles in S2.

[0037] Comparative Example 3 Compared with Example 1, this embodiment omits the ultrasonic processing step in S2.

[0038] Table 1 is a summary table of experimental data on the decomposition rate of fluorinated organic compounds and the amount of CaF2 (dry basis) in the embodiments and comparative examples of this application. Decomposition rate of fluorinated organic compounds: content of fluorinated organic compounds in the concentrate / content of fluorinated organic compounds in the treated solution.

[0039] Comparative Example 1, compared to Example 1, highlights the decisive role of "concentrated pretreatment". Although Comparative Example 1 directly treated the original dilute solution (12 mg / L), the concentration was too low, and even with the same molar ratio of reagents, the total amount of ·OH generated per unit volume was limited; more importantly, the synergistic effect of micro-nano bubbles and ultrasound depends on a certain concentration of contaminants to trigger effective collisions and energy transfer. The results showed that only 2.1 mg of CaF2 was generated in the unconcentrated state, indicating that fewer CF bond breaks occurred. Therefore, adsorption concentration is not only a means to improve efficiency, but also an effective way to initiate advanced oxidation reactions.

[0040] Compared to Example 1, in Comparative Example 2, the decomposition rate of fluorinated organic compounds plummeted to 56.3% and the CaF2 yield was less than half (31.3 mg) when micro- and nano-bubbles were absent. This was because the lack of an interfacial reaction field and internal energy burst point provided by the bubbles limited the ·OH generation pathway, making it difficult for pollutants to be "captured" to the reaction hotspot region, thus reducing the utilization rate of the oxidant. Therefore, micro- and nano-bubbles may act as "nanoreactors," forming a localized high oxidation potential region at their gas-liquid interface.

[0041] Comparative Example 3, compared to Example 1, shows that the decomposition rate is only 58.1% under conditions without ultrasound, similar to the case without bubbles. Therefore, ultrasound not only provides cavitation energy but also plays the following roles: breaking up bubble aggregation and maintaining micro / nano-scale distribution; enhancing mixing uniformity and avoiding local concentration differences; and accelerating Fe... 2+ / Fe 3+ Recycling and regeneration delays catalyst deactivation.

[0042] The results show that "ultrasound + micro / nano bubbles" is not a simple superposition, but forms a positive feedback loop - ultrasound promotes bubble generation and rupture, and bubble collapse in turn enhances the sound field intensity.

[0043] This application develops an integrated "adsorption-vacuum desorption" concentration technology, breaking through the bottleneck of difficult treatment of low-concentration fluorinated organic compounds; constructs a triple synergistic oxidation system of "micro-nano bubbles + ultrasound + Fenton", significantly improving the chain breaking efficiency of fluorinated organic compounds; realizes the directional conversion of fluorine and the resource recovery of CaF2, and promotes the transformation of pollution control to a circular economy.

[0044] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0045] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for decomposing mineralized fluorine-containing organic waste water, characterized by, Comprising S1, adsorption and desorption treatment of the fluorine-containing organic wastewater to obtain a concentrated solution thereof; S2, adding hydrogen peroxide and ferrous ions to a container containing the concentrated solution to obtain a mixed solution, adjusting the pH of the mixed solution to 2-4, the mass ratio of the hydrogen peroxide to the organic matter contained in the fluorine-containing organic wastewater being 1:1-2, the molar ratio of the hydrogen peroxide to the ferrous ions being 1-6:1, introducing micro-nano bubbles into the mixed solution and performing ultrasonic treatment; S3, adding calcium hydroxide to the treated mixed solution, and centrifuging to obtain calcium fluoride precipitate.

2. A method of decomposing mineralized fluorine-containing organic waste water according to claim 1, characterized by: In S1, the fluorine-containing organic wastewater is subjected to adsorption and concentration treatment by an activated carbon fiber felt adsorption bed, and the fluorine-containing organic matter content in the concentrated solution is 0.05-5 wt%.

3. A method of decomposing mineralized fluorine-containing organic waste water according to claim 1, characterized by: In S1, two groups of adsorption beds are provided, and the two groups of adsorption beds are subjected to adsorption and desorption treatment, respectively.

4. A method of decomposing mineralized fluorine-containing organic waste water according to claim 3, characterized by: In S1, superheated steam is used for purging, and then clean water is introduced for cooling to perform desorption.

5. The method of claim 1, wherein the method is characterized by: In S1, when superheated steam is used for purging, the outlet gas is connected to a sealed cooling device, and in the cooling device, the steam is condensed to form a vacuum, so that the adsorption system forms a vacuum environment, thereby strengthening the desorption process.

6. The method of claim 1, wherein the method further comprises: In S2, an immersed ultrasonic transducer is used for ultrasonic treatment. ​ 7. The method of claim 1, wherein the method further comprises: In S2, the gas of the micro-nano bubbles is oxygen, argon, nitrogen, or carbon dioxide. ​ 8. A method of decomposing mineralized fluorine-containing organic waste water according to claim 1, characterized by: In S2, a microporous aeration head or a perforated pipe is used to release the micro-nano bubbles, and the gas flow per liter of the concentrated solution is 0.01-2 L / min, and the time for introducing the micro-nano bubbles into the mixed solution and performing ultrasonic treatment is 5-60 min.

9. A method of decomposing mineralized fluorine-containing organic waste water according to claim 1, characterized by: In S3, the supernatant obtained after centrifuging the mixed solution is returned to S1 for recycling.

10. A method of decomposing mineralized fluorine-containing organic waste water according to claim 1, characterized by: In S3, the calcium hydroxide is calcium hydroxide slurry, and the solid content is 10-35 wt%.

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