A method for continuous in-depth photocatalytic degradation of phthalate plasticizers in all-weather water bodies

Abstract

The application discloses a kind of all-weather continuous depth photocatalytic degradation method of phthalate plasticizer in water body, utilizes D-A type double-ion doped functionalized g-C3N4 as heterogeneous photocatalyst, air is O2 source, at room temperature, atmospheric pressure and neutral condition, visible light driven all-weather continuous, depth degradation method of phthalate in water body.Under the drive of visible light, D-A type double-ion doped functionalized g-C3N4 photocatalytic degradation PAEs simultaneously coproduction H2O2, no light condition introduces divalent iron salt and the generated H2O2 constructs in-situ photo-Fenton system, perylene-3,4,9,10-tetracarboxylic dianhydride or 1,4,5,8-naphthalene tetracarboxylic anhydride unit, cyan functional group as photo-generated electron reservoir, release photo-generated electron, reduce Fe 3+ To Fe 2+ , realizes the relay degradation of PAEs.Realize the green, continuous, depth degradation of PAEs in aqueous phase under all-weather environmental conditions.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and new material preparation technology, specifically involving the synthesis of a series of visible light photocatalysts, DA-type dual-ion-doped functionalized g-C3N4; using DA-type ion-doped functionalized g-C3N4 as a heterogeneous visible light photocatalyst, with air as the O2 source, a continuous and deep degradation method for phthalates in water under all-weather conditions of room temperature, normal pressure and neutral conditions. Background Technology

[0002] Phthalate esters (PAEs) are one of the eight classes of endocrine disruptors. The toxicity of PAEs to organisms mainly manifests as interference with the endocrine system in humans and other organisms, affecting hormone secretion, the reproductive system, and the immune system, and producing carcinogenic and neurotoxic effects [Yu Xiaozhang, Le Dongming, Ren Yanfei. Degradation mechanisms of phthalates in the environment [J]. Ecological Science, 2015, 34(04): 180-187.]. PAEs mainly include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dioctyl phthalate (DOP), and diisooctyl phthalate (DEHP). Among them, DMP, DEP, and DOP are listed as priority pollutants in my country. Plastic products are a major source of PAE (polyester oxide) pollution in the environment. PAEs in plastic products are linked to the plastic matrix by hydrogen bonds or van der Waals forces, exhibiting independent chemical properties. Over time, PAEs are continuously released and accumulate in the environment. In addition, varnish spraying, plastic incineration, and the aging and volatilization of various plastic products (such as films and molding powders) also generate large amounts of PAEs. PAEs enter water bodies through both direct and indirect pathways. Industrial wastewater containing PAEs is discharged directly into the aquatic environment through rainwater leaching and soil infiltration during the use of agricultural plastic films and the dumping of solid waste such as plastic waste. Atmospheric PAEs migrate indirectly into water bodies through dry deposition or rainwater leaching. The low vapor pressure of PAEs makes it difficult for PAEs in water to migrate back into the atmosphere, resulting in the continuous accumulation of PAEs in the aquatic environment. In 2021, the average concentration of six priority controlled PAEs in Poyang Lake during the rainy season was 0.544 ± 0.173 μg / L. -1 During the dry season, the concentration almost doubles. The total concentration of PAEs in surface water along the Wuhan section of the Yangtze River ranges from 280.9 to 779.0 ng / L. -1 The total concentration of six PAEs in the Pearl River Estuary ranged from 0.50 to 28.1 μg / L. -1The detected PAEs are numerous and present in high concentrations, exceeding the permissible concentrations in my country's water environmental quality standards, posing an increasing environmental risk. Due to their relatively stable structure and low concentrations in the aquatic environment, PAEs present new challenges to existing technologies such as potassium permanganate oxidation, advanced oxidation technologies (represented by the Fenon process), separation membranes, and biotechnology.

[0003] Ultraviolet light has a good photodegradation ability for PAEs in the aquatic environment. Yuan et al. [Yuan, XZ, Graham N. Aqueous oxidation of dimethyl phthalate in a Fe(VI)-TiO2-UV reaction system[J]. Water Res. 2008, 42, 1413-1420.] combined UV with TiO2 and used Fe(VI)-TiO2-UV composite process to photodegrade DMP. In a typical environmental water body, the removal rate of DMP was 40% after 2 hours of degradation. Wu Jinghui et al. [Wu Jinghui. Kinetic study on degradation of PAEs in water by UV / H2O2 combined technology[J]. Environmental Sanitation Engineering, 2015, 23(06):28-32.] directly applied UV and H2O2 in combination to degrade DMP and DEP. When the initial concentration of PAEs was 5 mg / L and the H2O2 dosage was 330 mg / L, the degradation rates of DMP and DEP were 80.7% and 84%, respectively, showing good combined effects. Yang et al. [Yang GP, Zhao XK, et al. Oxidative degradation of diethyl phthalate by photochemically enhanced Fenton reaction[J]. J Hazard Mater, 2015, 126 (1): 112-118.] introduced UV-assisted Fenton oxidation to develop a UV / Fenton combined system, which was applied to the degradation of DEP. The DEP degradation rate was 75.8% after 120 min of reaction. To overcome the problems of difficult recovery and recycling of homogeneous Fenton reagents. Mesdaghinia et al. [Mesdaghinia A, Azari A, et al. Removal of phthalate esters (PAEs) by zeolite / Fe3O4: investigation on the magnetic adsorption separation, catalytic degradation and toxicity bioassay[J]. J Mol Liq, 2017, 233: 378-390.] prepared a heterogeneous Zeolite / Fe3O4 composite material by combining zeolite with Fe3O4 magnetic nanomaterials. Under the condition of H2O2 presence, the degradation rate of DEP reached 99.7% in 9 min.However, the above reports have shortcomings, including the inability to directly utilize sunlight (ultraviolet light accounts for less than 10.0% of sunlight), reliance on industrial H2O2 processing, safety hazards in transportation, storage, and use, and limitations on the large-scale application of ultraviolet light. (Li et al. [Li KX, Zeng ZX, et al. Fabrication of H3PW]) 12 O 40 -Dopedcarbon nitride nanotubes by one-step hydrothermal treatment strategy and their efficient visible-light photocatalytic activity toward representativeaqueous persistent organic pollutant degradation[J]. Appl Catal B: Environ.,2014,156:141-152.] Nanoscale heteropolyacids were introduced into the g-C3N4 structure to construct H3PW 12 O 40 The / C3N4 complex exhibited excellent photodegradation activity for DEP in aqueous phase under visible light, achieving a 100% degradation rate after 24 hours of illumination. This superior degradation activity is attributed to the synergistic photodegradation effect of the heteropolyacid and g-C3N4. Unoccupied orbitals in the heteropolyacid molecule, under light irradiation, generate holes and electrons that react with H2O and dissolved oxygen to form reactive oxygen species, which then further degrade PAEs into CO2 and H2O, following the action of g-C3N4.

[0004] In summary, the photocatalytic degradation of PAEs requires photoexcitation (and cannot function at night), is limited by weather and light source conditions, and relies on external H2O2, among other limitations. Therefore, this invention ① designs and synthesizes dual-ion-doped functionalized g-C3N4. By introducing alkali metal ions, ion bridges are built between and within the layers of its bulk phase, promoting the transport of photogenerated carriers and the separation of photogenerated electrons / holes. Hydroxyl functional groups are introduced through covalent bonds, endowing the g-C3N4 surface with certain amphiphilic activity, promoting the adsorption and reaction of molecular oxygen and water molecules at the interface, while simultaneously allowing the generated H2O2 to be promptly removed from the catalytically active sites. The introduction of cyano functional groups serves both as a reservoir for photogenerated electrons and as an active site for molecular oxygen adsorption. ② Through heterojunction engineering, naphthalenetetracarboxylic anhydride and perylenetetracarboxylic dianhydride, which have large conjugated systems, are introduced into the synthesized ion-doped functionalized g-C3N4 structure via amide covalent bonds to construct an organic-organic heterojunction. On the one hand, this heterojunction serves as a photon electron reservoir, introducing photogenerated electrons in a timely manner and reducing their aggregation at the interface and recombination with photogenerated holes. This improves the effective utilization of photogenerated electrons while achieving spatiotemporal matching between photophysical and chemical catalytic processes. On the other hand, it further increases the light absorption of g-C3N4. A g-C3N4-based complex with high visible light photocatalytic activity is constructed. Starting directly from aqueous solutions containing PAEs, H2O2 is co-produced while photocatalytically degrading PAEs. Divalent iron salts are introduced in situ to form a photo-Fenton system with co-produced H2O2, which then continuously degrades PAEs in water under visible light-driven, all-weather conditions. Summary of the Invention

[0005] One objective of this invention is to synthesize a series of highly crystalline sodium / potassium-doped hydroxyl / cyano-functionalized g-C3N4 ions via ionothermal polycondensation using dicyandiamide (D), melamine (M), melamine cyanurate (R), urea (U), urea, and thiourea (UT) as precursors and sodium chloride / potassium chloride as a eutectic salt. The high crystallinity enhances the light absorption of g-C3N4, and the sodium and potassium ions introduced through coordination construct electron channels on the surfaces and interlayers of the g-C3N4 bulk phase, respectively, enabling photogenerated electrons. - , photogenic h + Sufficient separation and rapid transport; the cyano functional group introduced into the molecular structure serves as a reservoir of photogenerated electrons, compensating for the spatiotemporal mismatch between the photogeneration and catalytic processes, and reducing electron emissions. - h +The combination of these components enhances the adsorption of molecular oxygen at the triazine active center, preventing the generation of superoxide radicals and improving the selectivity of H2O2 generation via the molecular oxygen two-electron reduction pathway. The introduction of hydroxyl functional groups endows the g-C3N4 surface with amphiphilic activity, which is beneficial for promoting the reaction of molecular oxygen and water molecules at the active site interface and the timely removal of generated H2O2, thereby reducing the occurrence of its oxidative decomposition side reactions. Based on the heterojunction strategy, using the amino functional groups in the ion-doped functionalized g-C3N4 molecular structure as reaction sites, naphthalenetetracarboxylic anhydride (PTB) or perylenetetracarboxylic dianhydride (PTA) structural units are introduced via in-situ acylation reactions through amide covalent bonds to construct organic-organic heterojunction DA-type ion-doped functionalized g-C3N4. On the one hand, the naphthalenetetracarboxylic anhydride or perylenetetracarboxylic anhydride structural units serve as photon electron reservoirs, introducing photogenerated electrons in a timely manner and reducing their polymerization and recombination at the interface. This improves the effective utilization of photogenerated electrons while achieving spatiotemporal matching between photophysical processes and chemical catalytic processes. On the other hand, it further increases the absorption of visible light by g-C3N4.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The DA-type dual-ion-doped functionalized g-C3N4 is synthesized via an ionothermal polycondensation reaction using dicyandiamide (D), melamine (M), melamine cyanurate (R), urea (U), or urea / thiourea (UT) as precursors and sodium chloride / potassium chloride as a eutectic salt under a nitrogen atmosphere. Further, the chemical formulas of the dual-ion-doped functionalized g-C3N4 are abbreviated as PCN-D, PCN-M, PCN-R, PCN-U, and PCN-UT. Starting from the synthesized PCN-R and PCN-UT, using the amino functional groups in their molecular structure as reaction sites and methyltrimethoxysilane as a co-condensing agent, a series of DA-type dual-ion-doped functionalized g-C3N4 are synthesized via an in-situ N-acylation reaction, introducing PTA or PTB structural units in a covalent bond form. Furthermore, the chemical formulas of the DA-type ion-doped functionalized g-C3N4 are abbreviated as: PCN-R@PTA, PCN-R@PTB, PCN-UT@PTA, and PCN-UT@PTB. Schematic structures of dual-ion-doped functionalized g-C3N4 and DA-type dual-ion-doped functionalized g-C3N4 are shown below. Figure 1 As shown.

[0008] Furthermore, the synthesis of DA-type ion-doped functionalized g-C3N4 includes the following steps:

[0009] Step S101: Dicyandiamide, melamine, cyanuric acid, melamine, urea, or urea / thiourea are thoroughly mixed and ground with different masses of sodium chloride / potassium chloride. The mixture is then placed in a box-type muffle furnace, and nitrogen gas is continuously introduced (5–15 ml / min). The heating rate is controlled at 1.2–2.5 °C / min, and the mixture is heated to 500–620 °C for 3–5 h. The crude product is thoroughly ground, washed thoroughly with deionized water and ethanol, and vacuum dried to constant weight to obtain the target products PCN-D, PCN-M, PCN-R, PCN-U, and PCN-UT.

[0010] Step S102: 0.8 g PCN-R or PCN-UT, 0.5 g methyltrimethoxysilane, 10 mg 1,4,5,8-naphthalenetetracarboxylic anhydride (PTB) or perylene-3,4,9,10-tetracarboxylic dianhydride (PTA), and an appropriate amount of ethanol were thoroughly mixed and ground, then placed in a tube muffle furnace. Under vacuum conditions, the temperature was increased at a rate of 1–2.0 °C / min to 350 °C, and the reaction was maintained for 4 h. The crude product was thoroughly ground, washed thoroughly with deionized water and ethanol, and vacuum dried to constant weight to obtain the target products PCN-R@PTA, PCN-R@PTB, PCN-UT@PTA, and PCN-UT@PTB.

[0011] The second objective of this invention is to provide a method that utilizes the aforementioned DA-type dual-ion doped functionalized g-C3N4 as a heterogeneous visible light catalyst to directly degrade PAEs in aqueous solutions containing PAEs, co-producing H2O2 through in-situ photo-Fenton oxidation. This method is applied to the continuous and deep degradation of PAEs in water under visible light-driven, all-weather conditions. This method features direct use of air as the O2 source, no need for external H2O2, operation under all-weather conditions, high catalytic activity, and recyclability.

[0012] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0013] A method for continuous and deep degradation of PAEs in water under all-weather conditions using the aforementioned DA-type dual-ion-doped functionalized g-C3N4 as a visible light catalyst and air as an O2 source: In wastewater containing PAEs, DA-type dual-ion-doped functionalized g-C3N4 catalyst, ethanol, and air as the O2 source are added. PAEs are degraded under visible light irradiation at room temperature, normal pressure, and neutral conditions. When there is no light irradiation, ferrous salts are added to continue the degradation reaction. This achieves visible light-driven photocatalytic degradation of PAEs and in-situ relay Fenton oxidation of H2O2. Specifically, under visible light irradiation, DA-type dual-ion-doped functionalized g-C3N4 photocatalytically degrades PAEs while simultaneously producing H2O2. Under no-light irradiation conditions, ferrous salts are added to in-situ convert the co-produced H2O2 into active oxide hydroxyl radicals, further deepening the degradation of PAEs.

[0014] Specifically, the following steps are included:

[0015] S300: In a quartz photocatalytic reaction flask equipped with magnetic stirring and circulating cooling water, add 10 mL of a 50 mg / L PAEs aqueous solution, 50 mL of seawater, 20 mg of catalyst, and 5 mL of ethanol sequentially. Air is continuously bubbled through the flask, and the reaction is carried out in the dark for 0.5 h to reach adsorption / desorption equilibrium. Then, a 300 W xenon lamp (equipped with a 420 nm or 1.5 G filter) is turned on, and the reaction is carried out for 6 h. Add...

[0016] 5 mL of FeSO4 aqueous solution (concentration 2.78 g / L) was stirred and reacted for 2 h.

[0017] Regeneration and recycling steps for DA-type dual-ion doped functionalized g-C3N4:

[0018] S301: The DA-type dual-ion-doped functionalized g-C3N4 obtained by centrifugation in step S300 is washed sequentially with anhydrous diethyl ether (3×50mL) and deionized water (3×50mL), and then vacuum dried at 60℃ to constant weight, thus completing the regeneration. The recycling of functionalized g-C3N4 is the same as in S300, except that the regenerated g-C3N4 is replaced with freshly prepared g-C3N4.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The DA-type dual-ion-doped functionalized g-C3N4 structure consists of dual-ion-doped functionalized g-C3N4 and either 1,4,5,8-naphthalenetetracarboxylic anhydride or perylene-3,4,9,10-tetracarboxylic dianhydride units. In the dual-ion-doped functionalized g-C3N4 structure, sodium and potassium ions introduced through coordination interactions construct electron channels on the surfaces and interlayers of the g-C3N4 bulk phase, respectively, enabling photogenerated electrons. - , photogenic h + Sufficient separation and rapid transport; the cyano functional group introduced into the molecular structure, on the one hand, enhances the adsorption of molecular oxygen at the triazine active center, prevents the generation of superoxide radicals, and improves the selectivity of H2O2 generation via the molecular oxygen two-electron reduction pathway; on the other hand, it acts as an auxiliary reservoir for photogenerated electrons to reduce e-. - h +The composite structure partially compensates for the spatiotemporal mismatch between photogenerated and catalytic processes. The introduction of hydroxyl functional groups endows the g-C3N4 surface with amphiphilic activity, which is beneficial for promoting the reaction of molecular oxygen and water molecules at the active site interface and the timely removal of generated H2O2, thereby reducing the occurrence of its oxidative decomposition side reactions. 1,4,5,8-naphthalenetetracarboxylic anhydride or perylene-3,4,9,10-tetracarboxylic dianhydride structural units are bonded to the dual-ion-doped functionalized g-C3N4 via amide covalent bonds to construct an organic-organic heterostructure. The introduced 1,4,5,8-naphthalenetetracarboxylic anhydride or perylene-3,4,9,10-tetracarboxylic dianhydride, on the one hand, acts as a photon electron reservoir, timely introducing photogenerated electrons and reducing their polymerization and recombination at the interface, thus compensating for the spatiotemporal mismatch between photophysical and chemical catalytic processes; on the other hand, it further increases the absorption of visible light.

[0021] 2. A DA-type dual-ion doped functionalized g-C3N4 is used as a heterogeneous photocatalyst. Air is used as the O2 source to photocatalytically degrade PAEs and co-produce H2O2. An in-situ photo-Fenton system is constructed by introducing divalent iron salts in situ to react with the generated H2O2. Perylenetetracarboxylic acid dianhydride or naphthalenetetracarboxylic acid anhydride units and cyano functional groups act as photogenerated electron reservoirs, releasing photogenerated electrons to reduce Fe. 3+ For Fe 2+ Following Fenton oxidation, continuous and deep degradation of PAEs in aqueous phase was achieved under visible light-driven all-weather environmental conditions (room temperature, normal pressure and neutral reaction conditions);

[0022] 3. DA-type dual-ion doped functionalized g-C3N4 is centrifuged, washed with anhydrous diethyl ether and deionized water, and vacuum dried to constant weight, then it can be regenerated and recycled. The catalytic activity remains basically unchanged after 5 cycles.

[0023] 4. This method starts directly from the aqueous phase containing PAEs, without the need for external H2O2, and the degradation is rapid and complete. It requires less iron salt and does not generate iron sludge during the process, thus achieving green, continuous and deep degradation of PAEs in the aqueous phase under all-weather environmental conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the synthesis route and structure of DA-type dual-ion doped functionalized g-C3N4 as described in this invention;

[0025] Figure 2 The image shows the FT-IR spectroscopy of the DA-type dual-ion doped functionalized g-C3N4 described in this invention.

[0026] Figure 3 This is a scanning electron microscope (SEM) image of the DA-type dual-ion doped functionalized g-C3N4 described in this invention.

[0027] Figure 4 This is an XRD pattern of the DA-type dual-ion doped functionalized g-C3N4 described in this invention.

[0028] Figure 5 This is a diagram illustrating the transient photocurrent response of the DA-type dual-ion doped functionalized g-C3N4 described in this invention.

[0029] Figure 6 This is a gas chromatography-mass spectrometry (GC-MS) image of the continuous deep degradation of DEP described in this invention.

[0030] Figure 7 This is a gas chromatography-mass spectrometry (GC) image of the continuous deep degradation of DEP described in this invention. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0032] Example 1: Synthesis of PCN-D, PCN-M, PCN-R, PCN-U, and PCN-UT

[0033] Step S101: Add 3g of dicyandiamide, or 5g of melamine, or 5g of melamine cyanurate, or 5g of urea, or 10g of a mixture of 5g urea and 5g thiourea to a mortar. Mix each mixture with 15g of a sodium chloride / potassium chloride mixture (sodium chloride / potassium chloride = 1:1.25 (molar ratio)) and grind thoroughly. Place the mixture in a muffle furnace under a nitrogen atmosphere, control the heating rate at 2.0℃ / min, heat to 550℃ and hold for 4 hours, then allow to cool naturally to room temperature. The crude product is thoroughly ground, washed thoroughly with deionized water and ethanol, and vacuum dried to constant weight to obtain the target product.

[0034] Example 2: Synthesis of DA-type dual-ion doped functional g-C3N4

[0035] Step S201: Add 0.8 g PCN-R or PCN-UT, 0.5 g methyltrimethoxysilane, 10 mg perylene-3,4,9,10-tetracarboxylic anhydride (PTA) or 1,4,5,8-naphthalenetetracarboxylic anhydride (PTB) sequentially to a mortar, and mix thoroughly with 10 mL of ethanol. Place the mixture in a muffle furnace under a vacuum atmosphere, control the heating rate at 2.0 °C / min, heat to 350 °C and maintain the temperature for 4 h, then allow it to cool naturally to room temperature. The crude product is thoroughly ground, washed thoroughly with deionized water and ethanol, and vacuum dried to constant weight to obtain the target products PCN-R@PTB-10, PCN-UT@PTB-10, PCN-R@PTA-10, and PCN-UT@PTA-10.

[0036] Application Example 1: Photocatalytic degradation of DEP and co-production of H2O2

[0037] In a quartz photocatalytic reaction flask equipped with magnetic stirring and circulating cooling water, 10 mL of DEP aqueous solution (concentration 50 mg / L), 50 mL of seawater, 20 mg of catalyst, and 5 mL of ethanol were added sequentially. Air was continuously introduced, and the reaction was carried out in the dark for 0.5 h to reach adsorption / desorption equilibrium. A 300 W xenon lamp (equipped with a 1.5 G filter or a 420 nm filter) was turned on for 6 h. Samples were taken every 1 h to measure the concentration of H2O2 and the DEP degradation rate. The results are shown in Table 1.

[0038] Table 1. Photocatalytic degradation of DEP and co-production of hydrogen peroxide

[0039]

[0040] Application Example 2: Photocatalytic Continuous Deep Degradation of Single Components of DEP, DMP, DBP, and DOP

[0041] In a quartz photocatalytic reaction flask equipped with magnetic stirring and circulating cooling water, 10 mL of DEP, DMP, DBP, or DOP aqueous solution (concentration 50 mg / L), 50 mL of seawater, 20 mg of catalyst, and 5 mL of ethanol were added sequentially. Air was continuously purged, and the reaction was carried out in the dark for 0.5 h until adsorption / desorption equilibrium was reached. A 300 W xenon lamp light source (equipped with a 1.5 G filter or a 420 nm filter) was turned on, and the reaction was carried out for 6 h. The light source was turned off, and 5 mL of FeSO4 aqueous solution (concentration 2.78 g / L) was added, and the reaction was stirred for 2 h. The results are shown in Table 2.

[0042] Table 2. Degradation results of photocatalytic in-situ relay Fenton DMP, DEP, DBP, and DOP

[0043]

[0044] Note [1] FeSO4 aqueous solution (concentration 2.78 g / L); [2] DEP degradation rate; [3] DMP degradation rate; [4] DBP degradation rate; [5] DOP degradation rate

[0045] Application Example 3: Photocatalytic continuous deep degradation of DEP, DMP, DBP, and DOP in two or three components

[0046] In a quartz photocatalytic reaction flask equipped with magnetic stirring and circulating cooling water, add sequentially 5 ml of a two-component aqueous solution of DEP-5 ml DBP or 5 ml of DEP-5 ml DOP (each DEP, DBP, and DOP aqueous solution concentration is 50 mg / L), or 3 ml of a three-component aqueous solution of DEP-3 ml DBP-3 ml DOP (each DEP, DBP, and DOP aqueous solution concentration is 50 mg / L), 50 mL of seawater, 20 mg of catalyst, and 5 mL of ethanol. Continuously purge with air and react in the dark for 0.5 h to reach adsorption / desorption equilibrium. Turn on a 300 W xenon lamp (equipped with a 1.5 G filter or a 420 nm filter) and react for 8 or 12 h. Turn off the light source, add 5 mL of FeSO4 aqueous solution (concentration 2.78 g / L), and stir the reaction for 2 h.

[0047] After 8 hours of degradation in the two-component system, the degradation rates of DEP, DBP, and DEP, DOP under visible light were 86% and 79%, and 83% and 70%, respectively; under simulated sunlight, the degradation rates of DMP, DEP, DBP, and DOP were 91% and 82%, and 75% and 67%, respectively. After 12 hours of degradation in the three-component system, the degradation rates of DEP, DBP, and DOP under visible light were 83%, 74%, and 68%, respectively; under simulated sunlight, the degradation rates of DEP, DBP, and DOP were 91%, 81%, and 77%, respectively.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A continuous deep photocatalytic degradation method for phthalate plasticizers in water bodies under all weather conditions, characterized in that: In wastewater containing PAEs, a DA-type dual-ion-doped functionalized g-C3N4 catalyst was added. Ethanol and air were used as the O2 source. Under room temperature, normal pressure, and neutral conditions, PAEs were degraded under visible light irradiation. When there was no light irradiation, ferrous salt was added to continue the degradation reaction. This achieved visible light-driven photocatalytic degradation of PAEs and in-situ relay Fenton oxidation of H2O2. That is, under visible light irradiation, DA-type dual-ion-doped functionalized g-C3N4 photocatalytically degrades PAEs and simultaneously produces H2O2. Under no light irradiation, the addition of ferrous salt converts the co-produced H2O2 in situ into active oxide hydroxyl radicals, which then further degrades PAEs. The DA-type dual-ion doped functionalized g-C3N4 molecular structure consists of two units: dual-ion doped functionalized g-C3N4 and naphthalenetetracarboxylic anhydride or perylenetetracarboxylic dianhydride, which are bonded together by amide covalent bonds. The naphthalenetetracarboxylic anhydride or perylenetetracarboxylic anhydride unit with a near-planar conjugated structure is introduced to serve as a photogenerated electron reservoir and to increase the light absorption of g-C3N4. The dual-ion doped functionalized g-C3N4 molecular structure introduces hydroxyl and cyano functional groups through covalent bonds, and sodium and potassium ions are inserted into the surface and interlayer of the g-C3N4 bulk phase through coordination bonds. The synthesis of the DA-type dual-ion doped functionalized g-C3N4 includes the following steps: Step S301: Using one or more of dicyandiamide, melamine, melamine cyanurate, urea, and thiourea as precursors, and KCl and NaCl eutectic salts as hot molten salts, the mixture is thoroughly ground in a mortar and then added to a crucible. The crucible is placed in a box-type muffle furnace, and nitrogen gas is continuously introduced. The heating rate is controlled at 1.2-3.5℃ / min, and the mixture is heated to 500-650℃ for 3-5 h. The crude product is thoroughly ground, thoroughly washed with deionized water and ethanol, and vacuum dried to constant weight to obtain dual-ion doped functionalized g-C3N4. Step S302: 0.8 g of dual-ion-doped functionalized g-C3N4, 0.5 g of methyltrimethoxysilane, 10 mg of perylene-3,4,9,10-tetracarboxylic dianhydride PTA or 1,4,5,8-naphthalenetetracarboxylic anhydride PTB, and 5-15 mL of ethanol are thoroughly mixed and ground in a mortar. The mixture is placed in a tube muffle furnace and heated to 350°C under vacuum conditions, with a heating rate controlled at 1-2.5°C / min. The reaction is maintained at this temperature for 4 h. The crude product is thoroughly ground, washed thoroughly with deionized water and ethanol, and vacuum dried to constant weight to obtain the DA-type dual-ion-doped functionalized g-C3N4.

2. The method according to claim 1, characterized in that: The ferrous salt mentioned is ferrous sulfate, ferrous chloride, or ferrous nitrate.

3. The method according to claim 1, characterized in that: The reaction system also includes seawater.

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