A BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 Synthesis methods and applications of photocatalytic materials

Abstract

A BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 This invention relates to the synthesis method and application of photocatalytic materials, belonging to the field of perfluorinated and polyfluorinated compound (PFAS) treatment technology in water. This invention addresses the technical problems of poor adsorption selectivity for PFASs, oxygen vacancy introduction-dependent post-treatment, and low catalytic efficiency in existing photocatalytic materials. Method: Bi(NO3)3 solution and NH4F solution are mixed and reacted in a high-pressure reactor, followed by washing and drying. This invention uses an ethylene glycol / water green solvent system and a one-step hydrothermal synthesis method, requiring no expensive equipment or complex post-treatment, and featuring a simple process and mild conditions. In application, it exhibits excellent stability, anti-interference ability, and low energy consumption characteristics under pure ultraviolet light or simulated sunlight irradiation, without the need for the addition of persulfate or an external electric field, providing a promising solution for the deep treatment of PFASs in actual water bodies. The photocatalyst prepared by this invention is used for the degradation of perfluorinated and polyfluorinated compounds.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology for perfluorinated and polyfluorinated compounds, specifically relating to a fluorine-rich bismuth fluoride oxidase photocatalytic material and its preparation method, as well as the application of this material in the selective adsorption and photocatalytic degradation of perfluorinated and polyfluorinated alkyl substances (PFASs), especially suitable for the highly selective adsorption and efficient photocatalytic degradation of perfluorinated and polyfluorinated alkyl substances in water. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic persistent organic pollutants. In their molecular structure, some or all hydrogen atoms in the carbon chain are replaced by fluorine atoms, forming CF bonds. Due to the highest electronegativity and small atomic radius of fluorine atoms, the bond energy of the CF bond is as high as approximately 536 kJ / mol, far exceeding that of CH and CC bonds, giving PFASs extremely high chemical stability, thermal stability, and resistance to biodegradation. At the same time, PFASs are both hydrophobic and oleophobic, exhibiting excellent surface activity, and are widely used in fire-fighting foams, food packaging, non-stick coatings, waterproofing of textiles, semiconductor manufacturing, and electroplating.

[0003] The persistence of PFASs in the environment has attracted widespread global attention. These substances have half-lives of up to decades in natural water bodies and can enter the aquatic environment through surface runoff, industrial wastewater discharge, and atmospheric deposition, accumulating in the food chain. Epidemiological studies have shown that PFASs have hepatotoxicity, immunotoxicity, reproductive and developmental toxicity, and potential carcinogenic risks. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the two most representative long-chain PFASs. In recent years, the use of short-chain perfluorocarboxylic acids such as perfluorohexanoic acid (PFHxA), perfluorobutyric acid (PFBA), and trifluoroacetic acid (TFA) as alternatives has been increasing, and their detection frequency and concentration in the environment are also on the rise. Although short-chain PFASs have relatively lower bioaccumulation, they are more polar and more difficult to retain by traditional adsorbents, and existing advanced oxidation technologies generally have low degradation efficiency, making them a technical challenge in the current water treatment field.

[0004] Traditional water treatment technologies have significant limitations in removing PFASs. Activated carbon adsorption and ion exchange only achieve phase transfer of pollutants, resulting in high-concentration fluoride-containing wastewater after adsorption saturation, requiring secondary treatment. Biological treatment processes are almost ineffective due to the high inertness of PFASs. While membrane separation technology can achieve retention, the concentrated solution is difficult to treat and membrane fouling is a problem. Among advanced oxidation technologies, reaction systems relying on hydroxyl radicals (·OH), such as Fenton oxidation and ozone oxidation, have minimal degradation effects on PFASs due to the limited ability of ·OH to break CF bonds. Photocatalytic oxidation technology, due to its ability to utilize clean light energy, mild reaction conditions, and strong oxidation capacity, has become a hot research area for PFAS degradation.

[0005] In photocatalytic materials, bismuth-based semiconductors have attracted widespread attention due to their unique layered structure and tunable band gap. Bismuth oxyfluoride belongs to the Sillén family of compounds and consists of a Bi₂O₂²⁺ layer and a bilayer of F₂O₃. - The ions are stacked alternately, with a band gap of about 3.6 eV. Theoretically, it mainly responds in the ultraviolet region and has a strong oxidation potential. There are reports of using BiOF to degrade PFOA in the existing technology, but such studies still have the following shortcomings: (1) BiOF has poor visible light response, and the degradation efficiency is limited by the energy of the light source; (2) The degradation performance is highly dependent on morphology regulation and lacks design of intrinsic defects of the material; (3) The degradation of short-chain PFASs, such as PFHxA and TFA, is extremely limited.

[0006] To address the issue of high recombination rates of photogenerated carriers, existing technologies attempt to improve performance by constructing heterojunctions or introducing oxygen vacancies. However, these technologies have significant drawbacks: (1) the introduction of oxygen vacancies usually relies on energy-intensive post-processing steps such as ultraviolet irradiation and reduction calcination, which are complex and costly; (2) the preparation of heterojunction materials is cumbersome and often requires the combination of electrochemical or external persulfate systems, increasing processing costs; (3) existing materials have poor adsorption selectivity for PFASs, making it difficult to achieve specific enrichment of target pollutants in complex water bodies, thus limiting catalytic efficiency.

[0007] Of particular note is that existing research on the photocatalytic application of BiOF mainly focuses on dye degradation (such as Rhodamine B and tetracycline) under visible light or simulated sunlight, with extremely limited research on strongly inert pollutants such as perfluorinated compounds. The extremely poor degradation effect of BiOF on PFHxA under visible, near-infrared, and full-spectrum irradiation indicates that conventional light sources cannot effectively excite BiOF to produce sufficiently strong oxidizing active species.

[0008] The core of photocatalytic degradation of perfluorinated compounds lies in the effective breaking of the CF bond. Studies have shown that the photon energy of 254 nm ultraviolet light is approximately 471 kJ / mol, which is still lower than the CF bond energy, resulting in limited direct photolysis efficiency. Indirect oxidation by generating highly reactive species through a photocatalyst is necessary. In contrast, the photon energy of 222 nm deep ultraviolet light is as high as approximately 539 kJ / mol, theoretically sufficient to directly break the CF bond or more efficiently excite wide-bandgap semiconductors to generate strongly oxidizing photogenerated holes. However, the photocatalytic behavior of BiOF in the 222 nm deep ultraviolet region has not been systematically reported. Whether the photon energy advantage of deep ultraviolet light can be utilized to achieve efficient degradation of short-chain perfluorocarboxylic acids is a scientific question that urgently needs to be explored in this field. Summary of the Invention

[0009] To address the technical problems of poor adsorption selectivity for PFASs, oxygen vacancy introduction-dependent post-processing, and low catalytic efficiency in existing photocatalytic materials, this invention provides a BiO4 material with oxygen vacancies and fluorine richness. 0.5 F 1.98 Synthesis methods and applications of photocatalytic materials.

[0010] A BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 A method for synthesizing photocatalytic materials, comprising the following steps:

[0011] (1) Dissolve Bi(NO3)3·5H2O in ethylene glycol to obtain solution A;

[0012] (2) Dissolve NH4F in an ethylene glycol / water mixture and sonicate to obtain solution B;

[0013] (3) Add solution B to solution A and stir magnetically continuously to obtain a mixed precursor; the molar ratio of F element in solution B to Bi element in solution A is 1:(1.8~2.5).

[0014] (4) The mixed precursor obtained in step (3) is transferred to a high-pressure reactor lined with polytetrafluoroethylene for reaction;

[0015] (5) After the reaction in step (4) is completed, the product is naturally cooled to room temperature, centrifuged to collect the solid product, and washed with water and ethanol in sequence.

[0016] (6) Dry the solid washed in step (5) to obtain BiO. 0.5 F 1.98 Photocatalytic materials.

[0017] Furthermore, in step (2), the volume ratio of ethylene glycol to water in the ethylene glycol / water mixed solution is 50% to 80%.

[0018] Furthermore, in step (3), the flow rate of solution B added to solution A is controlled to be 3~6 mL / s.

[0019] Furthermore, in step (4), the temperature is controlled at 150~210℃ and the reaction time is 12~20 h.

[0020] A BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 The application of photocatalytic materials, namely BiO4 with oxygen vacancies and fluorine-rich structures. 0.5 F 1.98 Photocatalytic materials are used as catalysts in the field of degradation of perfluorinated and polyfluorinated compounds.

[0021] A BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 The application of photocatalytic materials shall be carried out in the following steps:

[0022] I. BiO with oxygen vacancies and fluorine-rich elements 0.5 F 1.98 The photocatalytic material was added to a solution containing perfluorinated polyfluorinated compounds and stirred in the dark until adsorption equilibrium was reached.

[0023] II. Photocatalytic reaction under light irradiation.

[0024] Furthermore, the BiO4 with oxygen vacancies and fluorine-rich structure described in step one... 0.5 F 1.98 The dosage of photocatalytic material is 0.5~2 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds is 50~500 μg / L.

[0025] Furthermore, the perfluoropolyfluorinated compound is one or more of perfluorooctanoic acid, perfluorohexanoic acid, trifluoroacetic acid, and perfluorooctane sulfonic acid.

[0026] Furthermore, the light mentioned in step two is ultraviolet light.

[0027] Furthermore, the concentration changes of perfluorinated polyfluorinated compounds in the solution were measured, and samples were taken every 30 minutes to calculate the degradation rate.

[0028] This invention proposes a fluorine-rich BiO 0.5 F 1.98Preparation method and performance evaluation of the photocatalytic material. This material is synthesized via a one-step hydrothermal method, utilizing anion coordination competition mechanism to in-situ synergistically regulate fluorine doping and intrinsic oxygen vacancy concentration during synthesis, resulting in a unique structure characterized by lattice expansion, disordered anion arrangement, and high oxygen vacancy concentration. The material surface is fluorine-rich, forming nanoscale fluorine-enriched regions. Through the dual synergistic effect of fluorine-fluorine specific affinity and oxygen vacancy-carboxyl group coordination anchoring, highly selective adsorption and efficient photocatalytic degradation of PFASs are achieved. Under deep ultraviolet light irradiation, the material achieves a degradation rate of over 71% for PFHxA within 2.5 hours, and an adsorption rate of less than 10% for non-fluorinated organic compounds, providing a green and efficient new solution for the deep treatment of perfluorinated and polyfluorinated compounds in water.

[0029] This invention relates to a photocatalytic material BiO with oxygen vacancies and fluorine-rich components. 0.5 F 1.98 It has the following characteristics:

[0030] 1. Lattice expansion: due to excess F - Due to the presence of doping and oxygen vacancies, the material's unit cell volume expands, with an expansion rate of 3.5% to 5.0%.

[0031] 2. Disordered arrangement of anions: O in the anion layer 2- With F - It exhibits a disordered mixed distribution, reducing the ordered nature of the material structure;

[0032] 3. Intrinsic oxygen vacancies: High concentrations of intrinsic oxygen vacancies are formed in situ during the synthesis process, with an oxygen vacancy concentration of 8% to 25%, requiring no post-processing;

[0033] 4. Enhanced Lattice Distortion: Lattice distortion leads to enhanced atomic thermal vibration and a stronger built-in electric field, which is beneficial for the separation of photogenerated carriers. Furthermore, the surface of the photocatalytic material is rich in fluorine, with an F / Bi atomic ratio of 1.8~2.1, forming nanoscale fluorine-rich recognition sites that match the spatial structure of PFAS molecules.

[0034] Beneficial effects of this invention:

[0035] Material structure innovation: This invention is the first to propose and synthesize a BiO4 material with oxygen vacancies and fluorine richness. 0.5 F 1.98 Single-phase photocatalytic materials. BiOF belongs to the tetragonal or orthorhombic crystal system, and its unit cell parameters are relatively fixed under ideal conditions. BiO... 0.5 F 1.98 Due to excessive F - Partially replaces O 2- Furthermore, the presence of a large number of oxygen vacancies leads to significant changes in the crystal lattice: (1) Cell volume expansion: This material achieves excess F through anion coordination competition mechanism. -The in-situ synergistic construction of doping and high-concentration intrinsic oxygen vacancies leads to significant lattice expansion, resulting in a higher lattice size compared to BiOF. 0.5 F 1.98 The cell volume expands by about 3.5%~5.0%, forming a unique disordered anion layer structure; (2) Changes in the a-axis and c-axis: usually, the a-axis direction is slightly contracted, but due to the interlayer relaxation caused by oxygen vacancies, the c-axis direction is significantly stretched, resulting in an increase in overall volume and a decrease in cell symmetry; (3) The transformation from an ordered layered structure to a locally disordered structure may be accompanied by a decrease in symmetry. This structural innovation not only simplifies the traditional cumbersome process that requires post-processing to introduce defects, but also lays the foundation for subsequent efficient adsorption and catalysis.

[0036] Compared with existing bismuth oxyfluoride photocatalysts, this invention reveals for the first time the intrinsic correlation mechanism between fluorine richness and high oxygen vacancy concentration. Using a tetrahydrofuran system with a lower temperature and shorter reaction time, the product approaches the standard stoichiometric ratio of BiOF. Using an ethylene glycol / water solvent system with NaF as the fluorine source, the F / Bi atomic ratio is only 1.9 due to limitations in reaction temperature and fluorine source decomposition behavior, and the oxygen vacancy concentration is also significantly lower than in this invention. This invention achieves excess F during the anion coordination competition process through a precise process using NH4F as the fluorine source, ethylene glycol / water as the solvent, and a hydrothermal reaction at 180°C for 16 hours. - Incorporation. Due to F - The price is -1, O 2- The price is -2, when F - Occupy O 2- At the site, to maintain the overall electroneutrality of the crystal lattice, the system spontaneously induces the formation of a high concentration of intrinsic oxygen vacancies as charge compensation. Simultaneously, the formation of oxygen vacancies further alleviates the lattice stress caused by differences in ionic radius and charge, thus allowing for more F... - Stable doping into the crystal lattice. This fluorine-doped oxygen vacancy synergistic mechanism enables BiO to be stably incorporated into the crystal lattice. 0.5 F 1.98 The F / Bi atomic ratio is as high as 1.98, and the intrinsic oxygen vacancy concentration is 8%~25%, which far exceeds the level that can be achieved by post-processing or conventional stoichiometric materials.

[0037] A novel dual-mode adsorption mechanism: Existing photocatalytic materials (such as those in Figures 1 and 2, and conventional bismuth-based materials) primarily rely on hydrophobic interactions or electrostatic attraction for the adsorption of PFASs, exhibiting poor selectivity and susceptibility to interference from coexisting organic matter in water. The fluorine-rich surface of the material in this invention forms a nanoscale fluorine-rich region highly matched to the fluorocarbon chains of PFAS molecules, achieving specific molecular recognition of PFASs through fluorine-fluorine specific affinity interactions. Simultaneously, a positively charged region is formed near the intrinsic oxygen vacancies on the material surface, resulting in strong electrostatic attraction to the carboxyl head groups of PFASs through an oxygen vacancy-carboxyl group coordination anchoring effect. This dual-mode synergistic effect endows the material with extremely high adsorption selectivity and capacity. Experiments show that the material achieves a dark adsorption rate of 70.5% for trifluoroacetic acid (TFA), while the adsorption rates for non-fluorinated organic compounds such as bisphenol A (BPA) and nitrobenzene (NB) are both below 10%. This selective adsorption performance is significantly superior to existing bismuth-based photocatalytic materials, providing a novel solution for the targeted enrichment of PFASs in complex water bodies.

[0038] Adsorption-catalysis synergistic integrated design: The material of this invention achieves in-situ coupling between adsorption sites and catalytic active sites. PFAS molecules specifically adsorbed and enriched are located directly near the photocatalytic reaction active sites, shortening the time required for active species (such as photogenerated holes h⁺, superoxide radicals·O₂). - The migration distance of hydroxyl radicals (·OH) was reduced, enabling a seamless transition from adsorption enrichment to catalytic degradation. Radical quenching experiments confirmed that holes (h0.05) in the reaction system... + ) and superoxide radicals (·O2) - BiO₂ is the dominant reactive species driving degradation, while hydroxyl radicals are auxiliary reactive species. 0.5 F 1.98 Upon excitation by ultraviolet light, electrons from the valence band transition to the conduction band, leaving behind strongly oxidizing holes (h) in the valence band. + ), directly attacking the carboxyl head group (-COO) of PFASs. - This triggers a decarboxylation reaction, simultaneously breaking the CF bond, particularly in conjunction with the photon energy of 222 nm deep ultraviolet light (539 kJ / mol), directly breaking the CF bond and initiating the chain degradation reaction of PFASs molecules. Photogenerated electrons are captured by dissolved oxygen, undergoing a single-electron reduction reaction: e - +O2→·O2 - It assists in the degradation of short-chain perfluorocarboxylic acids and promotes the mineralization of intermediate products. Hole oxidation of water molecules or surface hydroxyl groups: h + +H₂O→·OH+H + It has an oxidizing effect on some intermediate products, but it is not a critical pathway.

[0039] Significant advantages in preparation process and application performance: Compared to tetrahydrofuran organic solvents, this invention uses an ethylene glycol / water green solvent system and a one-step hydrothermal synthesis method, requiring no expensive equipment or complex post-processing. The process is simple and the conditions are mild. In application, it only requires pure ultraviolet light or simulated sunlight irradiation, without the addition of persulfate or an external electric field, exhibiting excellent stability, anti-interference ability, and low energy consumption characteristics, providing a highly promising solution for the deep treatment of PFASs in actual water bodies.

[0040] The photocatalyst prepared in this invention is used to degrade perfluorinated and polyfluorinated compounds. Attached Figure Description

[0041] Figure 1 BiO prepared for the example 0.5 F 1.98 XRD comparison of photocatalytic material and standard BiOF;

[0042] Figure 2 BiO prepared for the example 0.5 F 1.98 Adsorption effect diagram of photocatalytic materials for perfluorinated and polyfluorinated compounds using dark adsorption;

[0043] Figure 3 BiO prepared for the example 0.5 F 1.98 A comparison of the performance of photocatalytic materials for perfluorinated and polyfluorinated compounds using different testing methods;

[0044] Figure 4 BiO prepared for the example 0.5 F 1.98 The efficiency results of photocatalytic materials for perfluorinated and polyfluorinated compounds and non-fluorinated substances using dark adsorption combined with photocatalysis are shown in the figure.

[0045] Figure 5 BiO prepared for the example 0.5 F 1.98 The experimental results of free radical quenching after photocatalysis using dark adsorption combined with photocatalysis are shown in the figure. Detailed Implementation

[0046] Specific Implementation Method 1: This implementation method uses a BiO4 containing oxygen vacancies and fluorine-rich elements. 0.5 F 1.98 A method for synthesizing photocatalytic materials, comprising the following steps:

[0047] (1) Dissolve Bi(NO3)3·5H2O in ethylene glycol to obtain solution A;

[0048] (2) Dissolve NH4F in an ethylene glycol / water mixture and sonicate to obtain solution B;

[0049] (3) Add solution B to solution A and stir magnetically continuously to obtain a mixed precursor; the molar ratio of F element in solution B to Bi element in solution A is 1:(1.8~2.5).

[0050] (4) The mixed precursor obtained in step (3) is transferred to a high-pressure reactor lined with polytetrafluoroethylene for reaction;

[0051] (5) After the reaction in step (4) is completed, the product is naturally cooled to room temperature, centrifuged to collect the solid product, and washed with water and ethanol in sequence.

[0052] (6) Dry the solid washed in step (5) to obtain BiO. 0.5 F 1.98 Photocatalytic materials.

[0053] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the volume ratio of ethylene glycol to water in the ethylene glycol / water mixed solution described in step (2) is 50%~80%. Everything else is the same as in Specific Implementation Method One.

[0054] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the flow rate of solution B added to solution A in step (3) is controlled to be 3~6 mL / s. Everything else is the same as in Specific Implementation Method 1 or 2.

[0055] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the temperature in step (4) is controlled at 150~210℃, and the reaction time is 12~20 h. Everything else is the same as in Specific Implementation Methods One to Three.

[0056] Specific Implementation Method 5: This implementation method uses a BiO4 containing oxygen vacancies and fluorine-rich elements. 0.5 F 1.98 The application of photocatalytic materials, namely BiO4 with oxygen vacancies and fluorine-rich structures. 0.5 F 1.98 Photocatalytic materials are used as catalysts in the field of degradation of perfluorinated and polyfluorinated compounds.

[0057] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that it uses a BiO4 containing oxygen vacancies and fluorine-rich elements. 0.5 F 1.98 The application of photocatalytic materials shall be carried out in the following steps:

[0058] I. BiO with oxygen vacancies and fluorine-rich elements 0.5 F 1.98 The photocatalytic material was added to a solution containing perfluorinated polyfluorinated compounds and stirred in the dark until adsorption equilibrium was reached.

[0059] 2. The photocatalytic reaction is carried out under light irradiation. Everything else is the same as in specific implementation method five.

[0060] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that: the BiO4 with oxygen vacancies and fluorine-rich content described in step one... 0.5 F 1.98 The dosage of the photocatalytic material is 0.5~2 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds is 50~500 μg / L. Other aspects are the same as in Specific Embodiment Six.

[0061] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods Six or Seven in that the perfluoropolyfluorinated compound is one or more of perfluorooctanoic acid, perfluorohexanoic acid, trifluoroacetic acid, and perfluorooctane sulfonic acid. Everything else is the same as in Specific Implementation Methods Six or Seven.

[0062] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Six to Eight in that the light used in step two is ultraviolet light. Everything else is the same as in Specific Implementation Methods Six to Eight.

[0063] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Six through Nine in that: the concentration change of perfluorinated and polyfluorinated compounds in the solution is measured, samples are taken every 30 minutes, and the degradation rate is calculated. Everything else is the same as in Specific Implementation Methods Six through Nine.

[0064] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0065] Example:

[0066] This embodiment describes a BiO4 containing oxygen vacancies and fluorine-rich elements. 0.5 F 1.98 A method for synthesizing photocatalytic materials, characterized by the following steps:

[0067] (1) Dissolve 2 mmol of Bi(NO3)3·5H2O in 20 mL of ethylene glycol to obtain solution A;

[0068] (2) Dissolve 2 mmol of NH4F in 20 mL of a 70% ethylene glycol / water mixed solution and sonicate for 30 min to obtain solution B;

[0069] (3) Add solution B dropwise into solution A and stir magnetically for 30 min to obtain a mixed precursor; the molar ratio of F element in solution B to Bi element in solution A is 1:(1.8~2.5).

[0070] (4) The mixed precursor obtained in step (3) was transferred to a high-pressure reactor with a 100 mL polytetrafluoroethylene liner and reacted at 180 °C for 16 h.

[0071] (5) After the reaction in step (4) is completed, the product is naturally cooled to room temperature, centrifuged to collect the solid product, and washed three times each with water and anhydrous ethanol.

[0072] (6) The solid washed in step (5) is dried at 80°C for 4 hours to obtain BiO. 0.5 F 1.98 Photocatalytic materials.

[0073] The example prepared a BiO with oxygen vacancies and fluorine-rich components. 0.5 F 1.98 The efficiency of photocatalytic materials in adsorbing and removing perfluorinated and polyfluorinated compounds was tested. The dark adsorption combined with photocatalysis method was carried out according to the following steps:

[0074] I. BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98 The photocatalytic material was added to a solution containing perfluorinated polyfluorinated compounds and stirred for 30 minutes in the dark.

[0075] II. Photocatalytic reaction was carried out under irradiation with a 15W 222nm ultraviolet lamp.

[0076] The BiO4 with oxygen vacancies and fluorine-rich structure described in step one 0.5 F 1.98 The dosage of the photocatalytic material was 1.0 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds was 100 μg / L.

[0077] The perfluorinated and polyfluorinated compounds targeted include perfluorohexanoic acid (PFHxA), sodium pentafluoropropionate (SPFP), trifluoroacetic acid (TBA), and other perfluorinated and polyfluorinated compounds, as well as bisphenol A (BPA) and nitrobenzene (NB).

[0078] Samples were taken every 30 minutes to measure the concentration changes of perfluorinated and polyfluorinated compounds in the solution and calculate the degradation rate. Step 3: After filtration through a 0.22 μm filter membrane, the concentration of perfluorinated compounds was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the concentration of other pollutants was analyzed by high performance liquid chromatography (HPLC).

[0079] The example prepared a BiO with oxygen vacancies and fluorine-rich components. 0.5 F 1.98 Dark adsorption efficiency test of photocatalytic materials:

[0080] BiO with oxygen vacancies and fluorine-rich 0.5 F 1.98The photocatalytic material was added to a solution containing perfluorinated and polyfluorinated compounds and stirred in the dark for 2.5 h. The perfluorinated and polyfluorinated compounds targeted pollutants including perfluorohexanoic acid (PFHxA), sodium pentafluoropropionate (SPFP), trifluoroacetic acid (TBA), bisphenol A (BPA), and nitrobenzene (NB). The BiO4 material, which has oxygen vacancies and is rich in fluorine, was also included. 0.5 F 1.98 The dosage of the photocatalytic material was 1.0 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds was 100 μg / L.

[0081] The reaction was carried out under dark adsorption for 2.5 h. Samples were taken every 30 minutes during the reaction, filtered through a 0.22 μm filter membrane, and the concentration of perfluorinated compounds was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The concentration of other pollutants was analyzed by high performance liquid chromatography (HPLC).

[0082] The example prepared a BiO with oxygen vacancies and fluorine-rich components. 0.5 F 1.98 Photocatalytic efficiency testing of photocatalytic materials:

[0083] I. BiO with oxygen vacancies and fluorine-rich elements 0.5 F 1.98 The photocatalytic material is added to a solution containing perfluorinated and polyfluorinated compounds; the perfluorinated and polyfluorinated compounds are perfluorohexanoic acid (PFHxA), sodium pentafluoropropionate (SPFP), trifluoroacetic acid (TBA), and other perfluorinated and polyfluorinated compounds, as well as bisphenol A (BPA) and nitrobenzene (NB) as pollutants; the BiO4 containing oxygen vacancies and fluorine-rich elements is used. 0.5 F 1.98 The dosage of the photocatalytic material was 1.0 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds was 100 μg / L.

[0084] The reaction was carried out under photocatalysis for 2 hours. Samples were taken every 30 minutes during the reaction, filtered through a 0.22 μm filter membrane, and the concentration of perfluorinated compounds was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The concentration of other pollutants was analyzed by high performance liquid chromatography (HPLC).

[0085] The test results of the example are as follows:

[0086] Figure 1 BiO prepared for the example 0.5 F 1.98 XRD comparison of photocatalytic material and standard BiOF.

[0087] BiO prepared in the examples was analyzed by X-ray diffraction (XRD). 0.5 F 1.98Crystal structure analysis was performed on the photocatalytic material. The results showed that the diffraction peaks of the prepared material shifted towards a smaller angle relative to the standard BiOF (PDF#22-0114), indicating lattice expansion and an increase in unit cell volume, confirming the presence of excess F. - The lattice distortion and disordered anion arrangement structure caused by the synergistic effect of doping and oxygen vacancies.

[0088] Figure 2 BiO prepared for the example 0.5 F 1.98 Adsorption effect diagram of photocatalytic materials for perfluorinated and polyfluorinated compounds using dark adsorption.

[0089] During the dark adsorption stage, the material in the examples showed an adsorption rate of 28.7% for perfluorohexanoic acid (PFHxA) and 70.5% for trifluoroacetic acid (TFA), while the adsorption rates for non-fluorinated organic compounds such as bisphenol A (BPA) and nitrobenzene (NB) were both below 10%. These results indicate that the material exhibits excellent selective adsorption capacity for perfluorinated and polyfluorinated compounds based on a dual synergistic effect of fluorine-fluorine specific affinity and oxygen vacancy-carboxyl coordination anchoring.

[0090] Figure 3 BiO prepared for the example 0.5 F 1.98 A comparison chart of the performance of photocatalytic materials on perfluorinated and polyfluorinated compounds using different testing methods.

[0091] For the BiO prepared in the examples 0.5 F 1.98 In the integrated adsorption-catalysis mode, the total removal rate of PFHxA reached 71.2% within 2 hours; while the removal rate in the dark adsorption mode (without light) was only 28.7%; and the removal rate in the photocatalysis mode alone (without pre-adsorption) was only 35.6%. The results show that the adsorption enrichment process significantly enhances the subsequent photocatalytic degradation efficiency, verifying the advantages of the integrated design of "adsorption site as catalytic site".

[0092] Figure 4 BiO prepared for the example 0.5 F 1.98 The efficiency results of photocatalytic materials for perfluorinated and polyfluorinated compounds and non-fluorinated substances using dark adsorption combined with photocatalysis are shown in the figure.

[0093] Under the integrated "dark adsorption + photocatalysis" mode, the present invention BiO 0.5 F 1.98The photocatalytic material exhibits excellent removal performance for perfluorinated and polyfluorinated compounds of varying chain lengths. For typical perfluorinated and polyfluorinated compounds such as perfluorohexanoic acid (PFHxA), trifluoroacetic acid (TFA), and sodium pentafluoropropionate (SPFP), the material achieves significant enrichment during the dark adsorption stage, followed by highly efficient photocatalytic degradation under 222 nm UV irradiation, maintaining a high overall removal rate. It also demonstrates good adsorption-catalytic synergistic removal for short-chain perfluorinated carboxylic acids such as TFA. In contrast, the removal rates for non-fluorinated organic compounds nitrobenzene (NB) and bisphenol A (BPA) are extremely low throughout the reaction. This indicates that the material of this invention achieves a synergistic effect of highly selective enrichment and efficient photocatalytic degradation of perfluorinated and polyfluorinated compounds based on a dual-mode synergistic effect of "fluorine-fluorine affinity" and "vacancy-carboxyl anchoring," while exhibiting almost no interference with non-fluorinated organic compounds, thus demonstrating excellent selectivity.

[0094] Figure 5 BiO prepared for the example 0.5 F 1.98 The experimental results of free radical quenching after photocatalysis using dark adsorption combined with photocatalysis are shown in the figure.

[0095] Hole scavenger (EDTA-2Na), superoxide radical scavenger (p-benzoquinone, P-BQ), and hydroxyl radical scavenger (tert-butanol, TBA) were added to the reaction system, respectively. The results showed that the addition of EDTA-2Na and P-BQ significantly inhibited the degradation efficiency of PFHxA, while the addition of TBA had a smaller impact on the degradation efficiency. This indicates that hole (h) radical scavenger (p-benzoquinone, P-BQ) can inhibit the degradation efficiency of PFHxA. + ) and superoxide radicals (·O2) - ) is the main active species of the material of this invention in the photocatalytic degradation of PFASs, and hydroxyl radical (·OH) is the auxiliary active species.

[0096] In summary, the fluorine-rich BiO provided by this invention... 0.5 F 1.98 Photocatalytic materials, through their unique structural design and dual-mode adsorption mechanism, achieve a combination of highly selective enrichment and efficient photocatalytic degradation of PFASs, providing a novel technical solution for the treatment of persistent organic pollutants in water.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A BiO4 with oxygen vacancies and fluorine-rich content 0.5 F 1.98 The method for synthesizing photocatalytic materials is characterized by This method is performed in the following steps: (1) Dissolve Bi(NO3)3·5H2O in ethylene glycol to obtain solution A; (2) Dissolve NH4F in an ethylene glycol / water mixture and sonicate to obtain solution B; (3) Add solution B to solution A and stir magnetically continuously to obtain a mixed precursor; the molar ratio of F element in solution B to Bi element in solution A is 1:(1.8~2.5). (4) The mixed precursor obtained in step (3) is transferred to a high-pressure reactor lined with polytetrafluoroethylene for reaction; (5) After the reaction in step (4) is completed, the product is naturally cooled to room temperature, centrifuged to collect the solid product, and washed with water and ethanol in sequence. (6) Dry the solid washed in step (5) to obtain BiO. 0.5 F 1.98 Photocatalytic materials.

2. The BiO4 with oxygen vacancies and fluorine-rich composition according to claim 1 0.5 F 1.98 The method for synthesizing photocatalytic materials is characterized by The volume ratio of ethylene glycol to water in the ethylene glycol / water mixed solution described in step (2) is 50% to 80%.

3. The BiO4 with oxygen vacancies and fluorine-rich content according to claim 1 0.5 F 1.98 The method for synthesizing photocatalytic materials is characterized by In step (3), the flow rate of solution B added to solution A is controlled to be 3~6 mL / s.

4. A BiO4 containing oxygen vacancies and rich in fluorine according to claim 1 0.5 F 1.98 The method for synthesizing photocatalytic materials is characterized by In step (4), the temperature is controlled at 150~210℃ and the reaction time is 12~20 h.

5. A BiO4 with oxygen vacancies and fluorine-rich elements 0.5 F 1.98 The application of photocatalytic materials is characterized by The BiO4 containing oxygen vacancies and fluorine-rich elements 0.5 F 1.98 Photocatalytic materials are used as catalysts in the field of degradation of perfluorinated and polyfluorinated compounds.

6. A BiO4 containing oxygen vacancies and fluorine-rich elements according to claim 5. 0.5 F 1.98 The application of photocatalytic materials is characterized by This application method is performed according to the following steps: I. BiO with oxygen vacancies and fluorine-rich elements 0.5 F 1.98 The photocatalytic material was added to a solution containing perfluorinated polyfluorinated compounds and stirred in the dark until adsorption equilibrium was reached. II. Photocatalytic reaction under light irradiation.

7. A BiO4 containing oxygen vacancies and fluorine-rich elements according to claim 6. 0.5 F 1.98 The application of photocatalytic materials is characterized by The BiO4 with oxygen vacancies and fluorine-rich structure described in step one 0.5 F 1.98 The dosage of photocatalytic material is 0.5~2 g / L, and the initial concentration of the solution containing perfluorinated polyfluorinated compounds is 50~500 μg / L.

8. A BiO4 containing oxygen vacancies and fluorine-rich elements according to claim 6. 0.5 F 1.98 The application of photocatalytic materials is characterized by Perfluoropolyfluorinated compounds are one or more of perfluorooctanoic acid, perfluorohexanoic acid, trifluoroacetic acid, and perfluorooctane sulfonic acid.

9. A BiO4 containing oxygen vacancies and fluorine-rich elements according to claim 6. 0.5 F 1.98 The application of photocatalytic materials is characterized by The light mentioned in step two is ultraviolet light.

10. A BiO4 containing oxygen vacancies and fluorine-rich elements according to claim 6. 0.5 F 1.98 The application of photocatalytic materials is characterized by The concentration change of perfluorinated polyfluorinated compounds in the solution was measured, and samples were taken every 30 minutes to calculate the degradation rate.

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