A polycyclic aromatic hydrocarbon degradation agent in water body, and a preparation method and application thereof

Abstract

The application discloses a polycyclic aromatic hydrocarbon degrading agent in water bodies, a preparation method and application thereof. The polycyclic aromatic hydrocarbon degrading agent comprises copper and chromium, and the content of the copper element is 1.0-2.0% and the content of the chromium element is 2.1-2.9% based on the weight of the polycyclic aromatic hydrocarbon degrading agent. The degrading agent is acid-resistant, alkali-resistant, stable, has wide adaptability to solution pH value, large specific surface area and moderate pore size, and when the degrading agent is used for polycyclic aromatic hydrocarbon degradation, the degrading rate is high, the speed is fast, the regeneration frequency is high and the operation is simple.

Description

Technical Field

[0001] This invention belongs to the field of polycyclic aromatic hydrocarbon (PAH) degradation agent preparation technology, specifically relating to a PAH degradation agent in water, its preparation method, and its application. Background Technology

[0002] Polycyclic aromatic hydrocarbons (PAHs) are aromatic hydrocarbons containing two or more benzene rings. They are widely sourced and diverse, possess stable physicochemical properties, are difficult to degrade, and are highly toxic, exhibiting carcinogenic, teratogenic, and mutagenic characteristics. Furthermore, they easily accumulate in the human body and other organisms, seriously endangering the ecological environment and human health. Statistics show that annual PAH emissions have reached tens of thousands of tons, of which nearly 2,000 tons are carcinogenic PAHs. Emitted PAHs are widely distributed in water bodies, soil, and the atmosphere. Among these, water bodies have high PAH concentrations and strong migration capabilities, becoming a significant component of the PAH migration cycle and causing serious water pollution. Effective treatment methods are urgently needed to efficiently remove PAHs from water bodies.

[0003] Catalytic oxidation is a commonly used method for the degradation of organic matter. While ensuring reaction efficiency, it offers advantages such as low oxidant dosage and high reaction rate between the oxidant and PAHs. In PAH wastewater treatment, advanced oxidation processes within catalytic oxidation have become an important research direction. The efficiency of an oxidation system mainly depends on whether it can generate sufficient and highly oxidizing hydroxyl radicals (·OH) under certain process conditions.

[0004] CN106345800A discloses a method for removing polycyclic aromatic hydrocarbons (PAHs) from soil using a persulfate-calcium peroxide composite oxidation process. The method involves sieving the air-dried soil to be tested, mixing it with calcium peroxide, adding distilled water to form a slurry, and then sequentially adding oxalate ions, ferrous ions, and persulfate ions, stirring until a homogeneous slurry reaction solution is obtained. This slurry reaction solution is then placed in the dark and allowed to stand until the reaction is complete, at which point PAHs are removed from the soil. This method is applicable to the removal of various PAHs from soil and has the advantage of high removal rate. However, this method simply mixes ferrous ions and persulfate ions with calcium peroxide for PAH removal, which is a one-time oxidation degradation process. The oxidant cannot be recovered or recycled, increasing degradation costs. Furthermore, the ferrous ions remain in the soil as iron sludge after the reaction, meaning excessive iron-containing substances remain in the soil, easily causing secondary pollution.

[0005] CN106807323A discloses a method for preparing a magnetic magnesium oxide adsorbent for adsorbing polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. This method utilizes superparamagnetic iron oxide nanoparticles as heterogeneous seed crystals added to a magnesium oxide precursor solution. After self-assembly and aging, a precipitate is obtained, which is then calcined at high temperature to obtain magnesium oxide microspheres with a particle size of 5 μm to 10 μm. The essence of this adsorption process is to introduce PAHs from the water into the adsorbent; it does not achieve the effect of directly degrading or decomposing them into other harmless substances. Furthermore, the regeneration process of the magnetic magnesium oxide adsorbent is difficult, hindering its industrial-scale application. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a polycyclic aromatic hydrocarbon (PAH) degrading agent for water, its preparation method, and its application. The degrading agent of this invention is acid- and alkali-resistant, exhibits good stability, has a wide pH adaptability, a large specific surface area, and a suitable pore size. Furthermore, when used for PAH degradation, the degrading agent of this invention demonstrates high degradation rate, rapid speed, multiple regeneration cycles, and simple operation.

[0007] The first aspect of the present invention provides a polycyclic aromatic hydrocarbon (PAH) degrading agent for water, comprising: copper and chromium, wherein the content of copper is 1.0% to 2.0% and the content of chromium is 2.1% to 2.9% based on the weight of the PAH degrading agent.

[0008] Furthermore, the BET specific surface area of ​​the degradation agent is 350 m². 2 / g~450m 2 / g, pore volume is 0.43cm³ 3 / g~0.58cm 3 / g, with a mesoporous content of 60%–77%.

[0009] A second aspect of this invention provides a method for preparing the above-mentioned polycyclic aromatic hydrocarbon degrading agent in water, comprising the following steps:

[0010] (1) Dissolve the water-soluble sodium salt in water, then add the first organic ligand and chromium-based hydrated salt, mix well, and then perform heat treatment;

[0011] (2) The mixture after heat treatment in step (1) is subjected to solid-liquid separation and dried to obtain the degradation agent carrier;

[0012] (3) The second organic ligand, copper-based hydrated salt and degradation agent carrier are dissolved in an organic solvent and reacted. Then the mixture after reaction is separated into solid and liquid and dried to obtain the degradation agent.

[0013] Further, in step (1), the water-soluble sodium salt is selected from one or more of anhydrous sodium acetate, anhydrous sodium sulfate, and anhydrous sodium chloride, preferably anhydrous sodium acetate.

[0014] Further, in step (1), the first organic ligand is selected from one or more of terephthalic acid, pyromellitic acid, and 2,6-naphthalenedicarboxylic acid, preferably 2,6-naphthalenedicarboxylic acid.

[0015] Further, in step (1), the chromium-based hydrated salt is selected from one or more of chromium nitrate nonahydrate, chromium chloride hexahydrate, and chromium sulfate hexahydrate, preferably chromium nitrate nonahydrate.

[0016] Furthermore, in step (1), the method of achieving uniform mixing can be by stirring. The stirring time is 20 min to 40 min, and the stirring speed is 300 rpm to 500 rpm.

[0017] Further, in step (1), the mass ratio of the water-soluble sodium salt, the first organic ligand, the chromium-based hydrated salt and the deionized water is 1:(7.5-15.6):(13.7-25.5):(175-325), preferably 1:(9-12):(17.5-21.5):(230-275).

[0018] Further, in step (1), the heat treatment temperature is 160℃~240℃, preferably 190℃~210℃, and the heat treatment time is 5h~20h, preferably 10h~15h. The heat treatment can be carried out by adding the material into the reactor and transferring it to a drying oven. The reactor is a stainless steel reactor with a polytetrafluoroethylene liner.

[0019] Further, in step (2), the mixture after heat treatment in step (1) is cooled to room temperature before solid-liquid separation. After solid-liquid separation, it is washed and then dried. The solid-liquid separation can be carried out using conventional methods in the art, such as vacuum filtration.

[0020] Further, in step (2), the washing solvent is one or more of N,N-dimethylformamide, anhydrous ethanol, and acetone, preferably anhydrous ethanol.

[0021] Further, in step (2), the drying temperature is 100℃~200℃, preferably 135℃~175℃, and the drying time is 5h~20h, preferably 8h~13h.

[0022] Further, in step (3), the second organic ligand is selected from one or more of 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, and pyromellitic acid, preferably 1,3,5-benzenetricarboxylic acid.

[0023] Further, in step (3), the copper-based hydrated salt is selected from one or more of copper sulfate pentahydrate, copper chloride dihydrate, and copper nitrate trihydrate, preferably copper nitrate trihydrate.

[0024] Further, in step (3), the organic solvent is selected from one or more of N,N-dimethylformamide, anhydrous methanol, and diethyl ether, preferably N,N-dimethylformamide.

[0025] Further, in step (3), the mass ratio of the second organic ligand, copper-based hydrated salt, degradation agent carrier and organic solvent is 1:(0.25-5):(0.5-10):(10-80), preferably 1:(0.75-3.5):(2-6):(30-60).

[0026] Furthermore, in step (3), the reaction temperature is 50℃~90℃, preferably 60℃~80℃.

[0027] Furthermore, in step (3), the reaction can be carried out by stirring. The stirring time is 1h to 10h, preferably 5h to 8h, and the stirring speed is 300rpm to 500rpm.

[0028] Furthermore, in step (3), after the solid-liquid separation, the mixture is washed and then dried. The solid-liquid separation can be carried out using conventional methods in the art, such as vacuum filtration.

[0029] Further, in step (3), the washing solvent is selected from one or more of deionized water, N,N-dimethylformamide, and anhydrous ethanol, preferably N,N-dimethylformamide.

[0030] Furthermore, in step (3), the drying temperature is 80℃~150℃, preferably 110℃~130℃, and the drying time is 5h~24h, preferably 12h~16h.

[0031] A third aspect of the present invention provides the application of the above-mentioned degrading agent in the degradation of polycyclic aromatic hydrocarbons in water.

[0032] Furthermore, the application includes mixing an aqueous solution of polycyclic aromatic hydrocarbons, the degradation agent, and hydrogen peroxide, adjusting the pH value, and carrying out an oxidative degradation reaction.

[0033] Furthermore, the polycyclic aromatic hydrocarbon is selected from either fused-ring or non-fused-ring polycyclic aromatic hydrocarbons. For example, naphthalene.

[0034] Furthermore, the concentration of the polycyclic aromatic hydrocarbon aqueous solution is 50 mg / L to 2000 mg / L.

[0035] Furthermore, the mass concentration of the hydrogen peroxide is 1% to 10%, preferably 4% to 6%.

[0036] Further, the mass ratio of the polycyclic aromatic hydrocarbon aqueous solution, the degrading agent, and hydrogen peroxide is 1:(0.0005-0.01):(0.0001-0.003), preferably 1:(0.0008-0.003):(0.0004-0.001).

[0037] Furthermore, the pH value is adjusted to 4–12, preferably 6–8.

[0038] Further, the pH value is adjusted using a dilute acid aqueous solution or a dilute alkali aqueous solution. The dilute acid aqueous solution is selected from any one of dilute hydrochloric acid aqueous solution, dilute nitric acid aqueous solution, and dilute citric acid aqueous solution. The dilute alkali aqueous solution is selected from any one of dilute sodium hydroxide aqueous solution, ammonia aqueous solution, and dilute potassium hydroxide aqueous solution. The mass concentration of the dilute acid aqueous solution is 0.001 mol / L to 0.01 mol / L. The mass concentration of the dilute alkali aqueous solution is 0.001 mol / L to 0.01 mol / L.

[0039] Furthermore, the pH value is adjusted under stirring conditions. The stirring speed is 300 rpm to 500 rpm.

[0040] Furthermore, the oxidative degradation reaction is carried out at room temperature, which is 20°C to 30°C.

[0041] Furthermore, the oxidative degradation reaction time is 20 min to 120 min, preferably 40 min to 70 min.

[0042] Furthermore, the degradation agent achieves a polycyclic aromatic hydrocarbon removal rate of 80%–90% when the pH value is 6–8, the aqueous solution concentration of polycyclic aromatic hydrocarbons (such as naphthalene) is 1000 mg / L, and the reaction temperature and time are 25°C and 60 min, respectively.

[0043] The fourth aspect of the present invention provides a method for regenerating the above-mentioned degradation agent.

[0044] Furthermore, the regeneration method of the degrading agent includes: after the degrading agent has been oxidized and degraded, the mixture after oxidized degradation is subjected to vacuum filtration, the resulting filter cake is soaked in an organic solvent, then vacuum filtered again, and the resulting filter cake is dried to obtain the regenerated degrading agent.

[0045] Furthermore, the organic solvent is selected from one or more of anhydrous methanol, N,N-dimethylformamide, and chloroform, with chloroform being preferred.

[0046] Furthermore, the soaking time is 10h to 30h, preferably 18h to 24h.

[0047] Furthermore, the drying temperature is 80℃~150℃, preferably 110℃~130℃, and the drying time is 5h~24h, preferably 12h~16h.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) This invention uses a complexation coordination method to prepare the degradation agent, preferably 2,6-naphthalenedicarboxylic acid as the first organic ligand. Due to its high spatial extension and symmetry, it forms a robust covalent bond structure during the coordination reaction with chromium-based hydrated salts, which is not easily replaced by water molecules, acid molecules, or base molecules. Subsequently, as a carrier, during the cross-linking reaction with copper-based coordination substances, an interwoven network structure is formed between the two, thereby generating more mesoporous structural units, providing an opportunity for polycyclic aromatic hydrocarbons in water to enter the pores for degradation reactions.

[0050] (2) The present invention uses chromium-based ligands as degradation agent carriers, which not only have stable performance, but also help to highly disperse active components (such as copper-based substances), which is beneficial to improve their catalytic oxidation degradation reaction activity.

[0051] (3) The present invention degrades polycyclic aromatic hydrocarbons in water through the synergistic effect of the degrading agent and hydrogen peroxide. On the one hand, the coordinating unsaturated active sites in the degrading agent molecule increase the number and probability of hydrogen peroxide generating hydroxyl radicals, so that the polycyclic aromatic hydrocarbons entering the degrading agent can be degraded efficiently. On the other hand, the coordinating unsaturated active sites in the degrading agent also enable hydrogen peroxide to generate hydroxyl radicals in a wider pH range, so that the reaction can be rapidly degraded in a near-neutral water environment.

[0052] (4) The preparation method of the present invention is simple, highly controllable, and the reaction process is safe and environmentally friendly, making it suitable for industrial-scale mass degradation of polycyclic aromatic hydrocarbons in water. Attached Figure Description

[0053] Figure 1 The infrared spectrum (FT-IR) of the degradation agent prepared in Example 1;

[0054] Figure 2 Scanning electron microscope (SEM) image of the degradation agent prepared in Example 1;

[0055] Figure 3 Scanning electron microscope (SEM) image of the degradation agent prepared in Example 1 after use;

[0056] Figure 4 Scanning electron microscope (SEM) image of the degradation agent prepared in Comparative Example 1;

[0057] Figure 5 Scanning electron microscope (SEM) images of the degradation agent prepared in Comparative Example 1 after use;

[0058] Figure 6 The removal rate of naphthalene from water by the degradation agent prepared in Example 1 at different pH values;

[0059] Figure 7 The removal rate of different polycyclic aromatic hydrocarbons in water by the degradation agent prepared in Example 1 at pH=7. Detailed Implementation

[0060] The following examples further illustrate the preparation method and degradation process of the polycyclic aromatic hydrocarbon (PAH) degrading agent in water according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0061] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0062] In this invention, the infrared spectrum of the degrading agent was determined using a Tensor II Fourier transform infrared spectrometer from Bruker, Germany. Samples were prepared using the potassium bromide pellet method, and the testing range was 4000 cm⁻¹. -1 ~500cm -1 .

[0063] In this invention, the content of each metal in the degradation agent is quantitatively analyzed using an XDL 230 X-ray fluorescence spectrometer (XRF) manufactured by Fischer GmbH, Germany.

[0064] In this invention, the morphology and particle size of the degradation agent were observed using a Japanese Hitachi S-4700 field emission scanning electron microscope (SEM).

[0065] In this invention, the specific surface area and pore volume of the degradation agent were determined using a 3H-2000PM2 specific surface area analyzer manufactured by Beijing Bestech Co., Ltd. Before testing, the samples underwent vacuum degassing at 373K, and nitrogen adsorption-desorption isotherms were tested at 77K. The specific surface area and pore volume of the samples were analyzed using the BET method.

[0066] Mesopority % = (Mesopore volume / Total pore volume) × 100%

[0067] In this invention, a Shimadzu UV-2700 UV-Vis spectrophotometer was used to determine the adsorption capacity of copper-based metal-organic framework materials for polycyclic aromatic hydrocarbons (PAHs) (calculated as naphthalene) in water. 1000 mg of naphthalene was weighed and placed in a volumetric flask, and dissolved using ultrasound. The required amount of deionized water was added to the volumetric flask, and the solution was brought to a final volume to obtain a naphthalene solution of the specified concentration. A quantitative amount of the naphthalene solution, a degradation agent, and hydrogen peroxide were then mixed and subjected to adsorption equilibrium under constant temperature shaking (25°C and 150 rpm).

[0068] Naphthalene removal rate % = [(initial concentration of naphthalene solution - adsorption equilibrium concentration of naphthalene solution) / initial concentration of naphthalene solution] × 100%.

[0069] Example 1

[0070] At 25℃, 1.23g of anhydrous sodium acetate was dissolved in 300g of deionized water, followed by the addition of 12.96g of 2,6-naphthalenedicarboxylic acid and 24g of chromium nitrate nonahydrate. The mixture was stirred at 400rpm for 30min and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was then transferred to a drying oven and heat-treated at 200℃ for 12h. After the heat treatment, the mixture in the reactor was cooled to 25℃ and then filtered. The mixture was washed with anhydrous ethanol, and the resulting filter cake was transferred to a drying oven and dried at 150℃ for 10h to obtain the degradation agent carrier.

[0071] Take 2.5g of 1,3,5-benzenetricarboxylic acid, 5g of copper nitrate trihydrate and 10g of degradation agent carrier, dissolve them in 100g of N,N-dimethylformamide at 70℃, stir at 400rpm for 7h, filter, wash with N,N-dimethylformamide, transfer the resulting filter cake to a drying oven, dry at 120℃ for 15h to obtain the degradation agent.

[0072] At 25℃, 50g of a 1000mg / L naphthalene aqueous solution was weighed and mixed with 0.05g of the degradation agent and 0.03g of 5% hydrogen peroxide. The mixture was stirred at 400rpm and the pH was adjusted to 7 with a 0.001mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out for 55min. The resulting mixture was filtered and the filtrate was used for analysis. The degradation effect is shown in Table 2. The filter cake was placed in chloroform and soaked for 20h. After filtration, it was transferred to a drying oven and dried at 120℃ for 14h to obtain the regenerated degradation agent.

[0073] Example 2

[0074] At 20℃, 1.23g of anhydrous sodium acetate was dissolved in 282.9g of deionized water, followed by the addition of 11.07g of 2,6-naphthalenedicarboxylic acid and 21.52g of chromium nitrate nonahydrate. The mixture was stirred at 500rpm for 20min and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was then transferred to a drying oven and heat-treated at 190℃ for 10h. After heat treatment, the mixture in the reactor was cooled to 20℃ and then filtered. The mixture was washed with anhydrous ethanol, and the resulting filter cake was transferred to a drying oven and dried at 135℃ for 8h to obtain the degradation agent carrier.

[0075] Take 2.5g of 1,3,5-benzenetricarboxylic acid, 1.87g of copper nitrate trihydrate and 5g of degradation agent carrier, dissolve them in 75g of N,N-dimethylformamide at 60℃, stir at 400rpm for 5h, filter, wash with N,N-dimethylformamide, transfer the resulting filter cake to a drying oven, and dry at 110℃ for 12h to obtain the degradation agent.

[0076] At 25℃, 50g of a 1000mg / L naphthalene aqueous solution was weighed and mixed with 0.05g of the degradation agent and 0.03g of 5% hydrogen peroxide. The mixture was stirred at 400rpm, and the pH was adjusted to 7 with 0.001mol / L dilute hydrochloric acid aqueous solution. The reaction was allowed to proceed for 55min. The resulting mixture was then filtered, and the filtrate was used for analysis. The degradation effect is shown in Table 2. The filter cake was placed in chloroform and soaked for 20h. After filtration, it was transferred to a drying oven and dried at 120℃ for 14h to obtain the regenerated degradation agent.

[0077] Example 3

[0078] Same as Example 1, except that anhydrous sodium chloride is used instead of anhydrous sodium acetate to obtain the degradation agent.

[0079] Example 4

[0080] Same as Example 1, except that terephthalic acid is used instead of 2,6-naphthalenedicarboxylic acid to obtain the degradation agent.

[0081] Example 5

[0082] Same as Example 1, except that chromium sulfate hexahydrate is used instead of chromium nitrate nonahydrate to obtain the degradation agent.

[0083] Example 6

[0084] Same as Example 1, except that pyromellitic acid is used instead of 1,3,5-benzenetricarboxylic acid to obtain the degradation agent.

[0085] Example 7

[0086] Same as Example 1, except that copper sulfate pentahydrate is used instead of copper nitrate trihydrate to obtain the degradation agent.

[0087] Example 8

[0088] Same as Example 1, except that anhydrous methanol was used instead of N,N-dimethylformamide to obtain the degradation agent.

[0089] Example 9

[0090] Same as Example 1, except that in the preparation stage of the degradation agent carrier, the masses of 2,6-naphthalenedicarboxylic acid, chromium nitrate nonahydrate and deionized water were adjusted to 9.84g, 30.75g and 369g respectively to obtain the degradation agent.

[0091] Example 10

[0092] Same as Example 1, except that the masses of copper nitrate trihydrate, degradation agent carrier and N,N-dimethylformamide were adjusted to 0.75g, 20g and 200g respectively, while other reaction conditions and material composition remained unchanged, to obtain the degradation agent.

[0093] Example 11

[0094] The method for preparing the degradation agent is the same as in Example 1.

[0095] At 30℃, 50g of a 1000mg / L naphthalene aqueous solution was weighed and mixed with 0.15g of the degradation agent and 0.05g of 5% hydrogen peroxide. The mixture was stirred at 500rpm, and the pH was adjusted to 8 with 0.001mol / L dilute hydrochloric acid aqueous solution. The reaction was allowed to proceed for 70min. The resulting mixture was then filtered, and the filtrate was used for analysis. The degradation effect is shown in Table 2. The filter cake was placed in chloroform and soaked for 24h. After filtration, it was transferred to a drying oven and dried at 130℃ for 16h to obtain the regenerated degradation agent.

[0096] Comparative Example 1

[0097] Take 2.5g of 1,3,5-benzenetricarboxylic acid and 5g of copper nitrate trihydrate, dissolve them in 100g of N,N-dimethylformamide at 70℃, stir at 400rpm for 7h, filter, wash with N,N-dimethylformamide, transfer the resulting filter cake to a drying oven, and dry at 120℃ for 15h to obtain the degradation agent.

[0098] At 25℃, 50g of a 1000mg / L naphthalene aqueous solution was weighed and mixed with 0.05g of the degradation agent and 0.03g of 5% hydrogen peroxide. The mixture was stirred at 400rpm and the pH was adjusted to 7 with a 0.001mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out for 55min. The resulting mixture was filtered and the filtrate was used for analysis. The degradation effect is shown in Table 2. The filter cake was placed in chloroform and soaked for 20h. After filtration, it was transferred to a drying oven and dried at 120℃ for 14h to obtain the regenerated degradation agent.

[0099] Comparative Example 2

[0100] At 25℃, 1.23g of anhydrous sodium acetate was dissolved in 300g of deionized water, followed by the addition of 12.96g of 2,6-naphthalenedicarboxylic acid and 24g of chromium nitrate nonahydrate. The mixture was stirred at 400rpm for 30min and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was then transferred to a drying oven and heat-treated at 200℃ for 12h. After the heat treatment, the mixture in the reactor was cooled to 25℃ and then filtered. The mixture was washed with anhydrous ethanol, and the resulting filter cake was transferred to a drying oven and dried at 150℃ for 10h to obtain the degradation agent.

[0101] At 25℃, 50g of a 1000mg / L naphthalene aqueous solution was weighed and mixed with 0.05g of the degradation agent and 0.03g of 5% hydrogen peroxide. The mixture was stirred at 400rpm and the pH was adjusted to 7 with a 0.001mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out for 55min. The resulting mixture was filtered and the filtrate was used for analysis. The degradation effect is shown in Table 2. The filter cake was placed in chloroform and soaked for 20h. After filtration, it was transferred to a drying oven and dried at 120℃ for 14h to obtain the regenerated degradation agent.

[0102] Comparative Example 3

[0103] Same as Example 1, except that the mass concentration of hydrogen peroxide is increased to 20% to complete the degradation process.

[0104] Comparative Example 4

[0105] Same as Example 1, except that the mass of copper nitrate trihydrate was reduced to 0.5g to obtain the degradation agent and complete the degradation process.

[0106] Comparative Example 5

[0107] Same as Example 1, except that the mass of chromium nitrate nonahydrate was increased to 33.21g to obtain the degradation agent and complete the degradation process.

[0108] Test Example 1

[0109] The physicochemical properties of the degrading agents and adsorbents in Examples 1-11 and Comparative Examples 1-5 were determined, and the specific results are shown in Table 1.

[0110] Table 1. Performance of the degradatives and adsorbents prepared in the Examples and Comparative Examples

[0111]

[0112]

[0113] Figure 1The infrared spectrum of the sample from Example 1 is given, showing that at 688 cm⁻¹... -1 and 744cm -1 The absorption peaks at 1230 cm⁻¹ correspond to the stretching vibrations of Cr-O and Cu-O ion clusters in the degradation agent, respectively. -1 ~1700cm -1 The absorption peak at 3500 cm⁻¹ is the CO vibration peak in the carboxylic acid functional group. -1 The relatively broad absorption peaks nearby are due to the HO stretching vibration, indicating good compatibility between the copper-based coordination compound and the degradation agent carrier. Table 1 shows that the degradation agent prepared by the method of this invention has a high BET specific surface area and pore volume, as well as abundant mesoporous structural units, which provides an opportunity for the adsorption of polycyclic aromatic hydrocarbons in water. The BET specific surface area, pore volume, and mesopority of the sample in Example 1 reached 450 m². 2 / g, 0.58cm 3 The percentages of / g and 77% are due to the fact that during the cross-linking reaction between the degrading agent carrier and the copper-based coordination material, an interwoven network structure is generated. This process retains a large specific surface area of ​​the carrier material while simultaneously producing numerous mesoporous structural units. After adsorbing naphthalene components from water, the degrading agent prepared by the method of this invention, after regeneration, still retains a high BET specific surface area and pore volume, as well as a certain number of mesoporous structural units. This is because this invention uses 2,6-naphthalenedicarboxylic acid as the first organic ligand. Due to its highly extensible and symmetrical spatial structure, it forms a robust covalent bond structure during the coordination reaction with chromium-based hydrated salts, making it resistant to substitution by water molecules, acids, and bases. Therefore, the degrading agent exhibits high stability against water, acids, and bases. Figure 2 and Figure 3 The scanning electron microscope images of the sample before and after the reaction in Example 1 show that the sample still maintains a complete crystal morphology after the reaction. Figure 4 and Figure 5 Scanning electron microscope images of the Comparative Example 1 sample before and after the reaction are provided. It can be seen that the sample is more damaged after the reaction, and it is difficult to see the complete crystal morphology.

[0114] Test Example 2

[0115] The removal rate of naphthalene from water by the degrading agents in Examples 1-11 and Comparative Examples 1-5 was determined. The reaction temperature and time were 25°C and 60 min, respectively, the solution pH was 7, and the aqueous solution concentration of naphthalene was 1000 mg / L. The specific results are shown in Table 2.

[0116] Table 2. Removal rates of naphthalene by the degrading agents and adsorbents prepared in the Examples and Comparative Examples.

[0117]

[0118]

[0119] As shown in Table 2, the degradation agent prepared in this invention exhibits good removal efficiency and reusability in the process of degrading and removing naphthalene from water using this method. The removal rate of naphthalene for the example samples remained above 80%, with the removal rate of naphthalene for example 1 reaching 90%; while the removal efficiency of naphthalene for naphthalene in water by the comparative example samples was significantly lower than that of the example samples.

[0120] Test Example 3

[0121] Using the degradation agent prepared in Example 1, tests were conducted under the operating conditions of Example 1, with only the pH value changed. The test results are as follows: Figure 6 As shown. Figure 6 The removal rates of naphthalene by the sample of Example 1 at different pH values ​​are given. It can be seen that the removal rate of naphthalene by the sample of Example 1 is greater than 80% in the pH range of 4 to 12.

[0122] Using the degrading agent prepared in Example 1, and under the operating conditions of Example 1, only the types of polycyclic aromatic hydrocarbons were changed, and the test results are as follows: Figure 7 As shown. Figure 7 The removal rates of different types of polycyclic aromatic hydrocarbons (PAHs) by the sample in Example 1 are provided. At a solution pH of 7, the removal rate of different types of PAHs by the sample in Example 1 remained above 80%. This is because the degrading agent and hydrogen peroxide work synergistically to degrade PAHs in water. On the one hand, the unsaturated active sites within the degrading agent molecule increase the number and probability of hydroxyl radicals generated by hydrogen peroxide, enabling efficient degradation of PAHs entering the degrading agent. On the other hand, the unsaturated active sites in the degrading agent also allow hydrogen peroxide to generate hydroxyl radicals over a wider pH range, enabling rapid degradation in near-neutral water environments.

Claims

1. A method for preparing a polycyclic aromatic hydrocarbon (PAH) degrading agent for water, wherein the degrading agent comprises: Based on the weight of the polycyclic aromatic hydrocarbon degrader, the content of copper is 1.0%–2.0%, and the content of chromium is 2.1%–2.9%. The preparation method of the polycyclic aromatic hydrocarbon degrading agent includes the following steps: (1) Dissolve the water-soluble sodium salt in water, then add the first organic ligand and chromium-based hydrated salt, mix well, and then perform heat treatment; (2) The mixture after heat treatment in step (1) is subjected to solid-liquid separation and dried to obtain the degradation agent carrier; (3) The second organic ligand, copper-based hydrated salt and degradation agent carrier are dissolved in an organic solvent and reacted. Then the mixture after reaction is separated into solid and liquid components and dried to obtain the degradation agent. In step (1), the first organic ligand is 2,6-naphthalenedicarboxylic acid; In step (3), the second organic ligand is selected from at least one of 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, and pyromellitic acid; In step (1), the heat treatment temperature is 160℃~240℃ and the heat treatment time is 5h~20h.

2. The preparation method according to claim 1, characterized in that, In step (1), the water-soluble sodium salt is selected from one or more of anhydrous sodium acetate, anhydrous sodium sulfate, and anhydrous sodium chloride.

3. The preparation method according to claim 2, characterized in that, In step (1), the water-soluble sodium salt is anhydrous sodium acetate.

4. The preparation method according to claim 1, characterized in that, In step (1), the chromium-based hydrated salt is selected from one or more of chromium nitrate nonahydrate, chromium chloride hexahydrate, and chromium sulfate hexahydrate.

5. The preparation method according to claim 4, characterized in that, In step (1), the chromium-based hydrated salt is chromium nitrate nonahydrate.

6. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the water-soluble sodium salt, the first organic ligand, the chromium-based hydrated salt and the deionized water is 1: (7.5-15.6): (13.7-25.5): (175-325).

7. The preparation method according to claim 6, characterized in that, In step (1), the mass ratio of the water-soluble sodium salt, the first organic ligand, the chromium-based hydrated salt and the deionized water is 1: (9-12): (17.5-21.5): (230-275).

8. The preparation method according to claim 1, characterized in that, In step (1), the heat treatment temperature is 190℃~210℃ and the heat treatment time is 10h~15h.

9. The preparation method according to claim 1, characterized in that, In step (2), after solid-liquid separation, the mixture is washed and then dried. The washing solvent is one or more of N,N-dimethylformamide, anhydrous ethanol, and acetone, and / or the drying temperature is 100℃~200℃ and the drying time is 5h~20h.

10. The preparation method according to claim 9, characterized in that, In step (2), the washing solvent is anhydrous ethanol, and / or the drying temperature is 135℃~175℃ and the drying time is 8h~13h.

11. The preparation method according to claim 1, characterized in that, In step (3), the second organic ligand is 1,3,5-benzenetricarboxylic acid.

12. The preparation method according to claim 1, characterized in that, In step (3), the copper-based hydrated salt is selected from at least one of copper sulfate pentahydrate, copper chloride dihydrate, and copper nitrate trihydrate.

13. The preparation method according to claim 12, characterized in that, In step (3), the copper-based hydrated salt is copper nitrate trihydrate.

14. The preparation method according to claim 1, characterized in that, In step (3), the organic solvent is selected from at least one of N,N-dimethylformamide, anhydrous methanol, and diethyl ether.

15. The preparation method according to claim 14, characterized in that, In step (3), the organic solvent is N,N-dimethylformamide.

16. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of the second organic ligand, copper-based hydrated salt, degradation agent carrier and organic solvent is 1:(0.25-5):(0.5-10):(10-80).

17. The preparation method according to claim 16, characterized in that, In step (3), the mass ratio of the second organic ligand, copper-based hydrated salt, degradation agent carrier and organic solvent is 1:(0.75-3.5):(2-6):(30-60).

18. The preparation method according to claim 1, characterized in that, In step (3), the reaction temperature is 50℃~90℃.

19. The preparation method according to claim 18, characterized in that, In step (3), the reaction temperature is 60℃~80℃.

20. The preparation method according to claim 1, characterized in that, In step (3), the reaction is carried out by stirring while reacting, and the stirring time is 1h to 10h, and the stirring speed is 300rpm to 500rpm.

21. The preparation method according to claim 1, characterized in that, In step (3), after solid-liquid separation, the mixture is washed and then dried. The washing solvent is selected from at least one of deionized water, N,N-dimethylformamide, and anhydrous ethanol, and / or the drying temperature is 80℃~150℃ and the drying time is 5h~24h.

22. The preparation method according to claim 21, characterized in that, In step (3), the washing solvent is N,N-dimethylformamide, and / or the drying temperature is 110℃~130℃ and the drying time is 12h~16h.

23. The polycyclic aromatic hydrocarbon degrader prepared by the method according to any one of claims 1-22.

24. The polycyclic aromatic hydrocarbon degrading agent according to claim 23, characterized in that, The degradation agent has a BET specific surface area of ​​350 m². 2 / g~450m 2 / g, pore volume is 0.43cm³ 3 / g~0.58cm 3 / g, with a mesoporous content of 60%–77%.

25. The use of the polycyclic aromatic hydrocarbon degrading agent according to any one of claims 23-24 in the degradation of polycyclic aromatic hydrocarbons in water.

26. The application according to claim 25, characterized in that, The application involves mixing an aqueous solution of polycyclic aromatic hydrocarbons, the degradation agent, and hydrogen peroxide, adjusting the pH value, and carrying out an oxidative degradation reaction.

27. The application according to claim 25 or 26, characterized in that, The polycyclic aromatic hydrocarbons are selected from either fused-ring polycyclic aromatic hydrocarbons or non-fused-ring polycyclic aromatic hydrocarbons.

28. The application according to claim 26, characterized in that, The concentration of the polycyclic aromatic hydrocarbon aqueous solution is 50 mg / L to 2000 mg / L, and / or the mass concentration of the hydrogen peroxide is 1% to 10%.

29. The application according to claim 26, characterized in that, The mass ratio of the polycyclic aromatic hydrocarbon aqueous solution, the degrading agent, and hydrogen peroxide is 1:(0.0005~0.01):(0.0001~0.003).

30. The application according to claim 29, characterized in that, The mass ratio of the polycyclic aromatic hydrocarbon aqueous solution, the degrading agent, and hydrogen peroxide is 1:(0.0008~0.003):(0.0004~0.001).

31. The application according to claim 26, characterized in that, Adjust the pH value to 4-12.

32. The application according to claim 26, characterized in that, The oxidative degradation reaction time is 20 min to 120 min.

33. A method for regenerating a polycyclic aromatic hydrocarbon (PAH) degrading agent, characterized in that, The method includes filtration of the polycyclic aromatic hydrocarbon degrading agent after application according to any one of claims 25-32, soaking the resulting filter cake in an organic solvent, then filtration again, and drying the resulting filter cake to obtain a regenerated degrading agent.

34. The regeneration method according to claim 33, characterized in that, The organic solvent is selected from one or more of anhydrous methanol, N,N-dimethylformamide, and chloroform, and / or the soaking time is 10h to 30h, and / or the drying temperature is 80℃ to 150℃, and the drying time is 5h to 24h.

35. The regeneration method according to claim 34, characterized in that, The organic solvent is selected as chloroform, and / or the soaking time is 18h to 24h, and / or the drying temperature is 110℃ to 130℃ and the drying time is 12h to 16h.

Images