A hindered lewis acid-base pair type pyrovanadate copper catalyst, a preparation method and application thereof

Abstract

This invention discloses a hindered Lewis acid-base pair type copper pyrovanadate catalyst, its preparation method, and its application. The preparation method of the catalyst includes the following steps: adding a metavanadate solution to a copper salt solution under stirring conditions, continuing stirring after complete addition to ensure sufficient reaction, then transferring the resulting mixture to a reaction vessel for hydrothermal reaction, and after the reaction is completed, centrifuging to separate the solid, washing, and drying to obtain the hindered Lewis acid-base pair type copper pyrovanadate catalyst. This catalyst can promote singlet oxygen (… 1 The generation of O2 can be used to activate oxidants such as persulfate (PMS) to degrade organic pollutants in water. These organic pollutants include antibiotics, specifically at least one of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), doxycycline (DOX), and their derivatives. The preparation method of this invention is simple, can be mass-produced, and is inexpensive, thus possessing broad application prospects.

Description

Technical Field

[0001] This invention relates to a hindered Lewis acid-base pair type copper pyrovanadate catalyst, its preparation method and application, belonging to the technical field of environmental protection and water treatment. Background Technology

[0002] Antibiotics are antibacterial drugs that have been widely used in human and animal health, as well as in livestock and aquaculture, since their introduction. However, organisms cannot completely absorb them; approximately 70% of antibiotics are excreted in urine and feces, either as the original drug or as metabolites, and enter the environmental medium. In recent years, antibiotics have been frequently detected in natural water bodies (surface water and groundwater) and even drinking water in many regions both domestically and internationally. Although the concentration of antibiotics entering the environment is low, long-term residues can lead to the emergence of superbugs and the problem of "antibiotic resistance," seriously endangering environmental ecological security and human health. Therefore, antibiotics, as a new type of pollutant, have attracted widespread social attention. Developing a low-cost, simple-to-prepare, and high-performance catalyst to degrade antibiotic pollutants in water is of significant practical importance.

[0003] Fenton-like oxidation technology has advantages such as fast reaction rate, thorough oxidation, and environmental friendliness, and is widely used in the removal of antibiotics from water. It utilizes a solid-phase catalyst to react with peroxides (hydrogen peroxide (H2O2), permonosulfate (PMS), perdisulfate (PDS)) to generate oxidizing active species, thereby oxidizing and degrading pollutants into smaller molecules and even carbon dioxide, water, and inorganic salts. The properties of the catalyst determine the activation efficiency of the peroxides and the type of oxidizing active species. Currently, most reported Fenton-like systems utilize hydroxyl radicals (… . OH), sulfate radicals (SO4) .- Free radicals are the dominant oxidizing agents. Free radicals have strong oxidizing power and can deeply mineralize various pollutants; however, their non-selective degradation characteristic means their degradation behavior is affected by background components in the environmental matrix. Actual water bodies typically contain natural organic matter and Cl-. - HCO3 - NO3 - and H2PO4 - Inorganic salt ions, such as those mentioned above, have been shown to react with free radicals, competing with the pollutants to be removed, consuming the oxidation capacity of peroxides, and thus reducing the degradation efficiency of the target pollutants. In recent years, new research has found that non-radical Fenton-like systems have shown certain advantages in degrading pollutants in actual water bodies. Non-radicals are a class of electrophilic species with relatively weak oxidizing power, not easily affected by organic matter and inorganic salt ions in the environmental background, and can selectively degrade electron-rich organic pollutants. Among them, singlet oxygen (… 1O2 is a typical non-radical oxidizing agent that maintains excellent activity even in complex aquatic environments (such as under different pH conditions and with high concentrations of inorganic ions and natural organic matter); however, 1 The formation conditions for O2 are harsh, and the reaction energy barrier is higher than that of O2. . OH and SO 4. - The concentration is one to two orders of magnitude higher, making it difficult to generate directionally during the activation process of peroxides. Therefore, its contribution to the selective degradation of pollutants is often masked by free radicals. Therefore, increasing... 1 The yield of O2 in Fenton-like systems is crucial. Summary of the Invention

[0004] The purpose of this invention is to provide a hindered Lewis acid-base pair type copper pyrovanadate catalyst, its preparation method, and its application. The hindered Lewis acid-base pair type copper pyrovanadate catalyst prepared by this invention can activate oxidants (such as PMS) to produce... 1 O2 is used to achieve highly efficient and selective degradation of novel antibiotic pollutants. This catalyst is simple to prepare, economical, and exhibits good catalytic activity in antibiotic degradation.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first objective of this invention is to provide a method for preparing a hindered Lewis acid-base pair type copper vanadate pyrovanadate catalyst, comprising the following steps:

[0007] (1) A certain amount of metavanadate and divalent copper salt were added to deionized water and dissolved to obtain metavanadate solution and copper salt solution. The metavanadate solution was added dropwise to the copper salt solution under constant stirring. After the solution was completely added, stirring was continued for 2-4 hours to allow it to react fully and a mixed solution was obtained. In this reaction, metavanadate and copper salt reacted to generate bimetallic copper vanadium hydroxy oxide (copper pyrovanadate, Cu3V2O7(OH)2).

[0008] (2) The mixture was transferred to a high-pressure reactor with a polytetrafluoroethylene substrate and placed in an oven at a specific temperature for hydrothermal reaction. After the reaction was completed, the solid was separated by centrifugation, washed and dried to obtain a yellow-green powder, which is the hindered Lewis acid-base pair type copper vanadate pyrovanadate catalyst, denoted as Cu3V2O. 7-x (OH) y In the hydrothermal reaction, Cu3V2O7(OH)2 loses lattice oxygen or hydroxyl oxygen, transforming into Cu3V2O. 7-x (OH) y , of which 0 <X<7,0<y<2。

[0009] In the preparation method of the present invention, preferably, in step (1), the metavanadate is sodium metavanadate, potassium metavanadate or ammonium metavanadate, and the concentration of metavanadate is 0.08-0.12 mol / L; the divalent copper salt is copper nitrate trihydrate, copper sulfate or copper chloride; and the molar ratio of metavanadate to divalent copper salt is 2:3.

[0010] In the preparation method of the present invention, preferably, in step (2), the washing method is to wash with water and ethanol 3 to 4 times respectively; the drying temperature is 60 to 70°C and the time is 10 to 12 hours.

[0011] In the preparation method of the present invention, preferably, the hydrothermal reaction temperature in step (3) is 100-200℃ and the time is 2-6h; more preferably, the hydrothermal reaction temperature is 200℃. Through exploration, the catalyst synthesized at 200℃ has a better catalytic degradation effect, and 200℃ is convenient for operation in a common oven, and the operation is simple; the reaction time is preferably 2h. When the reaction time is less than 2h, the synthesized catalyst has an irregular morphology. When the reaction time exceeds 2h, the synthesized catalyst will agglomerate. Although the agglomeration phenomenon becomes more serious with the extension of time.

[0012] Another object of the present invention is to provide the Cu3V2O described above. 7-x (OH) y This catalyst is used to activate oxidants such as PMS, PDS, or H2O2 to degrade organic pollutants in water. The hindered Lewis acid-base pairs constructed on the catalyst surface can promote the activation of PMS. 1 Non-radical reactive species such as O2 can selectively degrade organic pollutants, including antibiotics, in complex water bodies. The antibiotics include at least one of TC, OTC, CTC, DOX, and their derivatives.

[0013] The Cu3V2O provided by this invention 7-x (OH) y When applying the degradation of antibiotics, the following steps can be used: [The steps are described in the original text, which is not directly related to the previous sentence.] 7-x (OH) y The pollutants were uniformly dispersed in the antibiotic-containing water sample, and the pollutants reacted with Cu3V2O. 7-x (OH) y The mass ratio was 15–30:1, PMS was added as an oxidant, and the reaction was carried out in a shaker at 180 rpm in a water bath for 10–30 min. Cu3V2O was removed by filtration. 7-x (OH) y The purified water is obtained. Preferably, the pH value of the water to be treated is about 7, which is suitable for the actual water body and does not require further adjustment.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention constructs catalysts with unique surface / electronic structures, altering the electron transfer and transport processes within the material. This allows for the targeted regulation of the activation pathway of peroxides, potentially promoting the activation of non-radical components. 1 The generation of O2. Hindered Lewis acid-base pairs possess unique reactivity. Constructing intrinsic electronic polarization centers by in-situ on the surface of hydroxyl metal oxides using hindered Lewis acid-base pairs is an important means of achieving targeted catalysis of small molecule compounds such as peroxides. In Lewis acid-base theory, Lewis acids have empty orbitals, and Lewis bases donate lone pairs of electrons; they typically form inert acid-base adducts via coordinate bonds. However, in the presence of Lewis acid-base pairs with significant steric hindrance, the Lewis acid and Lewis base, unable to form coordinate bonds due to steric hindrance, approach each other, forming an active region. This active region contains unquenched Lewis acidic and basic sites, capable of simultaneously accepting and donating electrons. Hindered Lewis acid-base pair catalysts exhibit better electron transfer rates and readily mediate greater electron gain and loss. Hindered Lewis acid-base pairs on the material surface tend to promote the breaking of SO bonds in PMS rather than OO bonds, thereby directionally activating PMS formation. 1 O2 degrades antibiotics. This invention utilizes bimetallic copper vanadium hydroxy oxide (copper pyrovanadate, Cu3V2O7(OH)2) as a catalyst precursor, and forms Cu3V2O by constructing hindered Lewis acid-base pairs on the surface of Cu3V2O7(OH)2. 7-x (OH) y This enables the efficient activation of oxidants such as PMS to selectively degrade antibiotic pollutants in complex water bodies via a non-radical pathway.

[0016] This invention uses relatively inexpensive metavanadates and divalent copper salts as raw materials to synthesize Cu3V2O via a one-step hydrothermal method. 7-x (OH) y The process is simple and easy to operate, and the catalyst yield can be increased by increasing the proportion of raw materials added by a certain factor.

[0017] This catalyst can promote the generation of non-free radicals, which can be used to activate the production of oxidants. 1 O2 enables the efficient and selective degradation of novel antibiotic pollutants such as TC, OTC, CTC, and DOX. This invention features a simple preparation method, can be mass-produced, and is inexpensive, thus possessing broad application prospects. Attached Figure Description

[0018] Figure 1 Cu3V2O7(OH)2 and Cu3V2O prepared in Example 1 of this invention 7-x (OH)y Scanning electron microscope image.

[0019] Figure 2 Cu3V2O7(OH)2 and Cu3V2O prepared in Example 1 of this invention 7-x (OH) y X-ray diffraction pattern.

[0020] Figure 3 Cu3V2O7(OH)2 and Cu3V2O prepared in Example 1 of this invention 7-x (OH) y Solid-state electron paramagnetic resonance image.

[0021] Figure 4 Cu3V2O7(OH)2 and Cu3V2O prepared in Example 1 of this invention 7-x (OH) y The graphs show the effect of activated PMS on TC degradation and the effect of TC degradation at different pH values, as well as the effect on the degradation of different antibiotics. The degradation conditions were: catalyst concentration 10 mg / L, PMS concentration 0.2 mM, and antibiotic concentration 20 mg / L.

[0022] Figure 5 Cu3V2O 7-x (OH) y The degradation effects of TC, OTC, CTC, and DOX in common anions and natural organic compounds are shown in the figure. The degradation conditions are: catalyst concentration 10 mg / L, PMS concentration 0.2 mM, antibiotic concentration 20 mg / L, organic matter concentration 5 mg / L and 10 mg / L, and anion concentration 10 mg / L.

[0023] Figure 6 Cu3V2O prepared in Example 1 of this invention 7-x (OH) y +PMS system reactive oxygen species detection results. Figure 6 (a) is superoxide radical (·O2) - ), Figure 6 (b) is 1 O2. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments, but the essence of the present invention is not limited to the embodiments described below. Unless otherwise specified, the methods described are conventional methods, and the materials described are available from publicly available commercial sources unless otherwise specified. Those skilled in the art should know that any simple modifications or substitutions based on the essence of the present invention fall within the scope of protection claimed by the present invention.

[0025] In the following examples, a FEI - Quanta 200 type scanning electron microscope (SEM) was used to characterize the morphology of the catalyst, a PANalytical X - ray diffractometer was used to characterize the crystal form and structural characteristics of the material, a Thermo Nicolet 8700 was used to analyze the surface chemical components of the catalyst, and an Agilent 1220 type high - performance liquid chromatography was used to detect the concentration of antibiotics in the treated water sample.

[0026] Example 1

[0027] A preparation method of a hindered Lewis acid - base pair type copper vanadate catalyst, comprising the following steps:

[0028] (1) Dissolve 0.7248 g of copper nitrate trihydrate in 30 mL of deionized water, perform ultrasonic treatment for 30 min, dissolve 0.2339 g of sodium metavanadate in 20 mL of water, and stir and dissolve at 80 °C. After the sodium metavanadate solution is cooled to room temperature, it is dropped into the copper nitrate trihydrate solution, and a yellow - green mixed solution is immediately obtained; the yellow - green mixed solution is continuously stirred at normal temperature and pressure for 4 h to fully react;

[0029] (2) Transfer the stirred mixed solution to a 100 - mL high - pressure reaction kettle with a polytetrafluoroethylene liner, place it in an oven and carry out hydrothermal reaction at 200 °C for 2 h. After the reaction is completed, centrifuge to separate the solid, wash and dry to obtain a yellow - green powder, that is, Cu3V2O 7-x (OH) y .

[0030] The yellow - green mixed solution prepared in the above step (1) contains Cu3V2O7(OH)2. To compare the properties of Cu3V2O7(OH)2 and Cu3V2O 7-x (OH) y , take a part of the yellow - green mixed solution prepared in step (1), separate the solid precipitate therein, wash it three times with water and ethanol respectively, and then dry it at 60 °C for 12 h to obtain Cu3V2O7(OH)2.

[0031] Figures 1-3 The SEM, XRD, and EPR diagrams of Cu3V2O7(OH)2 and Cu3V2O 7-x (OH) y (0 < X < 7, 0 < y < 2) are shown respectively. After characterizing the morphology by scanning electron microscopy, the SEM image shows that Cu3V2O7(OH)2 is nanoscale small particles, and Cu3V2O 7-x (OH) y has rod - like substances with a new growth length of about 1 μm. By using an X - ray diffractometer, the material is determined to be Cu3V2O7(OH)2. From the EPR diagram, it can be seen that Cu3V2O 7-x (OH)y The oxygen vacancy concentration in Cu3V2O7(OH)2 is significantly higher than that in Cu3V2O7(OH)2.

[0032] The above Cu3V2O7(OH)2 and Cu3V2O 7-x (OH) y Application in the degradation of TC in water: Weigh out Cu3V2O7(OH)2 and Cu3V2O prepared in Example 1. 7-x (OH) y 10 mg of each catalyst was added to 100 mL of a 20 mg / L TC water sample, along with 0.2 mM PMS. The reaction was carried out at 25°C. No pH adjustment is needed for better degradation. After thorough shaking in a shaker, samples were taken at regular intervals, filtered, and the TC content and total organic carbon (TOC) values ​​in the aqueous solution were measured. Figure 4 The reaction proceeded for 30 minutes using Cu3V2O. 7-x (OH) y It can remove 90% of TC pollutants, which is more effective than Cu3V2O7(OH)2; the degradation effect on TOC reaches 60%, which is significantly higher than the 20% of Cu3V2O7(OH)2.

[0033] Figure 6 Cu3V2O 7-x (OH) y +PMS system reactive oxygen species detection results show 1 O2 is the main reactive species in this reaction system.

[0034] Example 2

[0035] A method for preparing a hindered Lewis acid-base pair type copper vanadate pyrovanadate catalyst includes the following steps:

[0036] (1) Dissolve 2.8992 g of copper nitrate trihydrate in 120 mL of deionized water and sonicate for 30 min. Dissolve 0.9356 g of sodium metavanadate in 80 mL of water and stir at 80 °C. After the sodium metavanadate solution is cooled to room temperature, it is added dropwise to the copper nitrate trihydrate solution, and a yellow-green mixture is immediately obtained.

[0037] (2) The obtained yellow-green mixture was stirred at room temperature and pressure for 4 hours. The stirred mixture was then transferred to a 200 mL high-pressure reactor with a polytetrafluoroethylene substrate and placed in an oven for hydrothermal reaction at 200 °C for 2 hours. After the reaction was completed, the solid was separated by centrifugation, washed and dried to obtain a yellow-green powder, namely Cu3V2O. 7-x (OH) y .

[0038] The Cu3V2O prepared in Example 2 7-x (OH)y The catalyst was applied to simulate the degradation of TC in complex water samples: TC water sample preparation, with a TC concentration of 20 mg / L, and inorganic anions Cl... - HCO3 - NO3 - and H2PO4 - The concentrations of all catalysts were prepared to be 10 mg / L, and the concentrations of natural organic compounds humic acid (FA) and fulvic acid (HA) were prepared to be 5 mg / L and 10 mg / L, respectively. No pH adjustment was required for better results. 10 mg of the catalyst prepared in Example 2 was weighed and added to 100 mL of the above TC water sample, followed by the addition of 0.2 mM PMS. The mixture was thoroughly shaken in a shaker at 25°C. Samples were taken at regular intervals, filtered, and the TC content in the aqueous solution was determined. Figure 5 It can remove 90% of pollutants in 30 minutes, and the interfering factors have no significant effect on it.

[0039] The Cu3V2O prepared in Example 2 7-x (OH) y Catalyst applied to the degradation of CTC in simulated complex water samples: The Cu3V2O prepared in Example 2 was weighed... 7-x (OH) y 10 mg of catalyst was added to 100 mL of a 20 mg / L CTC water sample, and inorganic anions Cl... - HCO3 - NO3 - and H2PO4 - The concentrations of all reagents were prepared to be 10 mg / L, and the concentrations of FA and HA were prepared to be 5 mg / L and 10 mg / L, respectively. 0.2 mM PMS was added to all reagents, and the reaction was carried out at 25°C. No pH adjustment is needed for better degradation. After thorough shaking in a shaker, samples were taken at regular intervals, filtered, and the CTC content in the aqueous solution was measured. Figure 5 The reaction proceeded for 30 minutes using Cu3V2O. 7-x (OH) y It can remove 85% of pollutants, and has almost no effect on inorganic anions and natural organic matter.

[0040] The Cu3V2O prepared in Example 2 7-x (OH) y Catalyst applied to simulate OTC degradation in complex water samples: Cu3V2O prepared in Example 2 was weighed. 7-x (OH) y 10 mg of catalyst was added to 100 mL of a 20 mg / L OTC water sample, and inorganic anions Cl... - HCO3 - NO3 - and H2PO4- The concentrations of all reagents were prepared to be 10 mg / L, and the concentrations of FA and HA were prepared to be 5 mg / L and 10 mg / L, respectively. 0.2 mM PMS was added to all reagents, and the reaction was carried out at 25°C. No pH adjustment is needed for better degradation. After thorough shaking in a shaker, samples were taken at regular intervals, filtered, and the OTC content in the aqueous solution was determined. Figure 5 The reaction proceeded for 30 minutes using Cu3V2O. 7-x (OH) y It can remove 90% of contaminants, and interfering factors have almost no effect on it.

[0041] The Cu3V2O prepared in Example 2 7-x (OH) y Catalyst applied to simulate DOX degradation in complex water samples: Cu3V2O prepared in Example 2 was weighed. 7-x (OH) y 10 mg was added to 100 mL of a 20 mg / L DOX water sample, containing inorganic anions Cl. - HCO3 - NO3 - and H2PO4 - The concentrations of all reagents were prepared to be 10 mg / L, and the concentrations of FA and HA were prepared to be 5 mg / L and 10 mg / L, respectively. 0.2 mM PMS was added to all reagents, and the reaction was carried out at 25°C. No pH adjustment is needed for better degradation. After thorough shaking in a shaker, samples were taken at regular intervals, filtered, and the DOX content in the aqueous solution was determined. Figure 5 The reaction proceeded for 30 minutes using Cu3V2O. 7-x (OH) y It can remove 90% of pollutants, and has almost no effect on inorganic anions and natural organic matter.

[0042] It should be noted that, for the hydrothermal reaction temperature and time in step (2) of the preparation method of this invention, the preferred temperature is 200℃ and the time is 2h. However, in actual experiments, the target product can also be prepared when the temperature is in the range of 100-200℃, such as 100℃, 130℃, 150℃, 180℃, etc., and when the time is in the range of 2-6h, such as 2h, 3h, 5h, 6h, etc. These parameters can be conventionally selected by those skilled in the art in actual experiments, and will not be elaborated further in this patent.

[0043] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A process for the preparation of a hindered Lewis acid-base pair type copper pyrovanadate catalyst, characterized in that: The method comprises the following steps: adding the metavanadate solution into the divalent copper salt solution under stirring, continuing to stir after complete addition to make it fully react, then transferring the obtained mixed solution into a reaction kettle to perform hydrothermal reaction, and centrifugally separating the solid after the reaction is completed, and obtaining a yellow-green powder after washing and drying, i.e., the hindered Lewis acid-base pair type copper pyrovanadate catalyst; The temperature of the hydrothermal reaction is 200℃, and the time is 2h.

2. The process for the preparation of a hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 1, characterized in that: The metavanadate solution is obtained by dissolving metavanadate in hot water and cooling to room temperature; the concentration of the metavanadate in the metavanadate solution is 0.08-0.12 mol / L; and the metavanadate is sodium metavanadate, potassium metavanadate or ammonium metavanadate.

3. The method of preparing a hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 1, characterized by: The divalent copper salt solution is prepared by dissolving a divalent copper salt in water; the concentration of the divalent copper salt solution is 0.08-0.12 mol / L; and the divalent copper salt is copper nitrate trihydrate, copper sulfate or copper chloride.

4. The process for the preparation of the hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 1, characterized by the fact that: The molar ratio of the metavanadate in the metavanadate solution to the divalent copper salt in the divalent copper salt solution is 2:

3.

5. The process for the preparation of the hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 1, characterized by the fact that: The washing method is to wash 3-4 times with water and ethanol respectively; the drying temperature is 60-70℃, and the drying time is 10-12h.

6. A hindered Lewis acid-base pair type copper pyrovanadate catalyst, characterized by: The method is prepared by the preparation method of any one of claims 1-5.

7. The hindered Lewis acid-base pair type copper pyrovanadate catalyst as claimed in claim 6 for activating oxidizing agent for degradation of organic pollutants in water, characterized by: The method comprises the following steps: The hindered Lewis acid-base pair type copper pyrovanadate catalyst and the oxidant are uniformly dispersed in the water sample containing organic pollutants to be treated, and the organic pollutants in the water can be degraded and removed through catalytic degradation.

8. The hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 7 for use in the activation of an oxidizing agent for the degradation of organic pollutants in water, characterized by: The oxidant is peroxymonosulfate, peroxodisulfate or hydrogen peroxide.

9. The hindered Lewis acid-base pair type copper pyrovanadate catalyst according to claim 7 for activating an oxidizing agent to degrade organic pollutants in water, characterized by: The organic pollutants include antibiotic pollutants, and the antibiotic pollutants are at least one of tetracycline, oxytetracycline hydrochloride, aureomycin hydrochloride, doxycycline and derivatives thereof.

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