A modified gangue-coupled perylene imide composite material and its preparation method and application

Abstract

The present invention provides a modified gangue-coupled peryleneimide composite material, a preparation method, and applications thereof. The preparation method comprises the following steps: S1, calcining gangue to obtain calcined modified gangue; S2, immersing the calcined modified gangue in a solution containing a silane coupling agent and stirring to obtain amino-modified gangue; S3, adding the amino-modified gangue to a perylene diimide solution, adding triethylamine, stirring, and then adding a hydrochloric acid solution and stirring to obtain the modified gangue-coupled peryleneimide composite material. The modified gangue-coupled peryleneimide composite material significantly improves the stability and efficiency of peryleneimide in photocatalytic reactions.

Description

Technical Field

[0001] The present invention relates to the fields of environmental engineering and materials science, and in particular to a modified gangue-coupled perylene imide composite material, a preparation method thereof, and application in the field of photocatalysis. Background Art

[0002] Faced with increasingly severe global water and air pollution, the development of efficient, economical, and environmentally friendly pollutant treatment technologies has become a top priority in contemporary scientific research. Photocatalytic technology has attracted considerable attention due to its ability to degrade organic pollutants using sunlight or artificial light at ambient temperature and pressure. However, while traditional photocatalytic materials, such as TiO2, exhibit significant activity, their efficiency in practical applications remains to be improved due to limitations such as the easy recombination of photogenerated electron-hole pairs and low light utilization efficiency.

[0003] Perylene imide materials have attracted widespread attention in the field of photocatalysis in recent years due to their unique electronic structure and photochemical stability. These materials not only possess a broad absorption spectrum but also effectively separate and transfer photogenerated electron-hole pairs, significantly improving photocatalytic efficiency. Despite this, perylene imide still faces limitations in practical applications, such as a small surface area and insufficient active sites. Summary of the Invention

[0004] In order to solve the above problems of the prior art, the present invention provides a modified gangue-coupled perylene imide composite material and a preparation method and application thereof, which significantly improves the stability and efficiency of perylene imide in photocatalytic reactions.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a modified coal gangue-coupled perylene imide composite material comprises the following steps:

[0007] S1, calcining the coal gangue to obtain calcined modified coal gangue;

[0008] S2, immersing the calcined modified coal gangue in a solution containing a silane coupling agent and stirring to obtain amino-modified coal gangue;

[0009] S3, adding amino-modified coal gangue to the perylene diimide solution, adding triethylamine, stirring, and then adding hydrochloric acid solution, stirring to obtain a modified coal gangue coupled perylene diimide composite material.

[0010] Preferably, in S1, the calcination temperature is 500-700° C., and the calcination time is 3-4 hours.

[0011] Preferably, S1 specifically comprises: calcining the coal gangue, then immersing it in 2-4 M hydrochloric acid for 20-24 hours, and washing it to obtain calcined modified coal gangue.

[0012] Preferably, in S1, the coal gangue is obtained by the following method: crushing the coal gangue, passing it through a 200-400 mesh sieve, and washing it with water multiple times.

[0013] Preferably, S2 is specifically: immersing the calcined modified coal gangue in a solution containing 2% to 4% of a silane coupling agent, stirring at room temperature for 24 to 48 hours, washing with water and drying.

[0014] Preferably, in S2, the silane coupling agent is one of 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-aminopropyltriisopropoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0015] Preferably, in S3, the perylene diimide solution is obtained by the following method: under the protection of inert gas, perylene-3,4,9,10-tetracarboxylic dianhydride, aminopropionic acid and imidazole are mixed and heated at 100~110°C for 4~5h; the reaction mixture is cooled to room temperature and then dispersed in anhydrous ethanol and hydrochloric acid solution, filtered and the solid is collected, and the obtained solid is fixed, dried and dissolved in water.

[0016] Preferably, in S3, the ratio of amino-modified coal gangue, perylene diimide, and triethylamine is (2-5) g: (1-4) g: (336-834) μL.

[0017] The present invention provides a modified coal gangue coupled perylene imide composite material obtained by the above-mentioned preparation method.

[0018] The present invention provides application of the modified gangue-coupled perylene imide composite material in adsorption / photocatalytic synergistic treatment of organic pollutants or heavy metal ions.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention calcines coal gangue (CG) to activate its surface. The activated gangue is then surface-modified using a silane coupling agent to introduce amino groups, enhancing its interaction with organic molecules. The modified gangue is then used as a carrier and coupled with perylene diimide to form a composite material with excellent adsorption and photocatalytic properties. The abundant silicate components within the gangue form stable chemical bonds with the perylene diimide through the silane coupling agent, thereby improving the composite material's stability and enhancing its photocatalytic efficiency. By leveraging the natural structure of the gangue and the surface-modifying properties of the silane coupling agent, the invention significantly enhances the stability and efficiency of the perylene diimide in the photocatalytic reaction. The composite material exhibits significant photocatalytic activity under visible light irradiation and is particularly suitable for the adsorption and degradation of chromium (VI). Triethylamine, an organic base, is used in the reaction, primarily to regulate pH and promote dissolution. When amino-modified gangue is added to a PDI solution, triethylamine neutralizes the acidic protons in the system, preventing excessive acidity from affecting the reactivity of the amino groups and maintaining a suitable pH in the solution, thereby promoting effective bonding between PDI and the amino-modified gangue. Furthermore, the presence of triethylamine helps enhance the interaction between the amino groups and the carboxyl groups or other functional groups in PDI, thereby promoting the formation of a more stable composite structure. The addition of hydrochloric acid induces the formation of PDI supramolecular nanostructures. Since triethylamine is a base, the addition of hydrochloric acid rapidly lowers the pH of the solution, protonating PDI and promoting intermolecular self-assembly to form a stable supramolecular nanostructure. Furthermore, the addition of hydrochloric acid aids in the precipitation of the product, further strengthening the bonding between PDI and the amino-modified gangue. The material of the present invention is simple to prepare, inexpensive, and has potential for industrial application. This invention not only effectively utilizes waste gangue resources but also provides an environmentally friendly and efficient photocatalytic material, offering a new technical solution for addressing environmental pollution.

[0021] Furthermore, after calcining the gangue, it is subjected to acid washing treatment to remove metal impurities and some unstable components on the mineral surface.

[0022] Furthermore, the gangue is screened and pickled to ensure the consistency of particle size and remove dust and soluble impurities on the surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1XRD patterns of the products prepared in Examples 1-3; (a) XRD patterns of calcined modified coal gangue and amino-modified coal gangue; (b) XRD pattern of modified coal gangue coupled with perylene imide composite material.

[0025] Figure 2 Infrared spectra of the products prepared in Examples 1-3; (a) infrared spectrum of calcined modified coal gangue; (b) infrared spectrum of amino-modified coal gangue; (c) infrared spectrum of modified coal gangue coupled with perylene imide composite material.

[0026] Figure 3 SEM images of the products prepared in Examples 1-3; (a), (b), and (c) are unmodified coal gangue; (d), (e), and (f) are calcined modified coal gangue; (g), (h), and (i) are amino-modified coal gangue; (j), (k), and (l) are modified coal gangue-coupled perylene imide composite materials.

[0027] Figure 4 Figures 1-3 show the adsorption-photocatalytic synergistic performance of the products prepared in Examples 1-3. (a) shows the Cr(VI) removal efficiency of MCG-500, MCG-600, MCG-700, NMCG-500, NMCG-600, and NMCG-700. (b) shows the Cr(VI) removal efficiency of the modified gangue-coupled perylene imide composite. (c) shows the kinetic fitting curves of MCG-500, MCG-600, MCG-700, NMCG-500, NMCG-600, and NMCG-700. (d) shows the kinetic fitting curve of the modified gangue-coupled perylene imide composite.

[0028] Figure 5 This is a diagram showing the adsorption-photocatalytic recycling performance of the modified gangue-coupled perylene imide composite material prepared in Example 1-3. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0031] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the invention.

[0032] The preparation method of the modified gangue-coupled perylene imide composite material of the present invention comprises the following steps:

[0033] S1, calcining the coal gangue to obtain calcined modified coal gangue;

[0034] S2, immersing the calcined modified coal gangue in a solution containing a silane coupling agent and stirring to obtain amino-modified coal gangue;

[0035] S3, adding amino-modified coal gangue to the perylene diimide solution, adding triethylamine, stirring, and then adding hydrochloric acid solution, stirring to obtain a modified coal gangue coupled perylene diimide composite material.

[0036] In the present invention, S1 specifically comprises: calcining the gangue at 500-700°C for 3-4 hours for activation treatment, then immersing the gangue in hydrochloric acid with a concentration of 2-4 M for 20-24 hours to remove metal impurities and some unstable components on the surface of the mineral, and then washing with deionized water until the pH value reaches neutral.

[0037] The present invention further includes a pretreatment step of the coal gangue before S1: the coal gangue is crushed to 200-400 mesh, washed with deionized water multiple times to remove dust and soluble impurities on the surface, and sieved to ensure particle size consistency.

[0038] In the present invention, S2 is specifically: immersing the coal gangue in a solution containing a silane coupling agent with a concentration of about 2% to 4%; stirring at room temperature for 24 to 48 hours to allow the silane coupling agent molecules to react with the hydroxyl groups on the surface of the coal gangue to form stable chemical bonds, and then washing with deionized water and drying to obtain amino-modified coal gangue.

[0039] The silane coupling agent of the present invention is one of 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-aminopropyltriisopropoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0040] In the present invention, S3 is specifically as follows: slowly adding amino-modified coal gangue to a perylene diimide solution, adding triethylamine, stirring, and then adding HCl solution to form a PDI supramolecular nanostructure, washing with distilled water and anhydrous ethanol alternately by centrifugation until the pH value of the washing solution becomes neutral, collecting the solid, drying it, and grinding it into a powder for storage.

[0041] In the present invention, the ratio of amino-modified coal gangue, perylene diimide, and triethylamine is (2-5) g: (1-4) g: (336-834) μL.

[0042] The perylene diimide solution is prepared by heating perylene-3,4,9,10-tetracarboxylic dianhydride, aminopropionic acid, and imidazole at 100-110°C under inert gas for 4-5 hours; cooling the reaction mixture to room temperature and dispersing it in anhydrous ethanol and HCl solution; collecting the resulting red solid by filtration through a 0.22 μm membrane filter, drying the collected solid at 60-70°C, and then dissolving it in HCl.

[0043] The ratio of perylene-3,4,9,10-tetracarboxylic dianhydride, aminopropionic acid and imidazole is 3.5 mmol:28.0 mmol:18 g. The ratio of anhydrous ethanol and HCl solution is V (eth） :V (HCI） =1:3.

[0044] The modified gangue-coupled perylene imide composite material prepared by the present invention can adsorb / photocatalytically synergistically treat organic pollutants or heavy metal ions. The composite material is used for at least one specific photocatalytic reaction, including but not limited to photocatalytic water decomposition to produce hydrogen, photocatalytic degradation of dyes, photocatalytic degradation of organic pollutants or photocatalytic CO2 reduction.

[0045] Example 1

[0046] (1) The gangue was crushed to 400 mesh and washed with deionized water several times to remove dust and soluble impurities on the surface. Three portions of washed gangue were prepared and calcined at 500°C in a muffle furnace for 3 h for activation. The gangue was then immersed in 4 M hydrochloric acid for 20 h to remove metal impurities and some unstable components on the surface of the gangue. The gangue was then washed with deionized water until the pH value was neutral to obtain calcined modified gangue (MCG), which was recorded as MCG-500.

[0047] (2) Silane coupling agent treatment

[0048] The modified gangue obtained after pretreatment was immersed in a solution containing 3-aminopropyltriethoxysilane with a concentration of about 2% and stirred at room temperature for 24 h to allow the coupling agent molecules to react with the hydroxyl groups on the surface of the gangue to form stable chemical bonds. The gangue was then washed again with deionized water and dried to obtain amino-modified gangue (NMCG), which was recorded as NMCG-500.

[0049] (3) Preparation of coal gangue-coupled perylene imide composite photocatalytic materials

[0050] First, 3.5 mmol of perylene-3,4,9,10-tetracarboxylic dianhydride, 28.0 mmol of aminopropionic acid, and 18 g of imidazole were heated at 100°C in an inert atmosphere for 4 h. The reaction mixture was cooled to room temperature and dispersed in 100 mL of anhydrous ethanol and 300 mL of 2.0 mol / L HCl. The resulting red solid was collected by filtration through a 0.22 μm membrane filter, dried at 60°C, and dissolved in deionized water to prepare 200 mL of perylene diimide (PDI) solution. 2 g of NMCG was slowly added to the PDI solution, 834 μL of triethylamine was added, and the mixture was stirred for 1 h. Then, 27.3 mL of 4.0 mol / L HCl was added and stirred for 12 h to form PDI supramolecular nanostructures. The solution was washed alternately by centrifugation with distilled water and anhydrous ethanol until the pH value of the washing solution became neutral. The collected solid was dried completely at 60°C and then ground into powder for storage to obtain a modified coal gangue-coupled perylene imide composite material (PNMCG), which was designated as PMNCG-500.

[0051] Example 2

[0052] The process is basically the same as Example 1, except that the calcination temperature in step (1) is 600°C, and MCG-600, NMCG-600, and PNMCG-600 are obtained in step (1), step (2), and step (3), respectively.

[0053] Example 3

[0054] The process is basically the same as Example 1, except that the calcination temperature in step (1) is 700°C, and MCG-700, NMCG-700, and PNMCG-700 are obtained in step (1), step (2), and step (3), respectively.

[0055] Example 4

[0056] (1) The gangue was crushed to 200 mesh and washed with deionized water several times to remove dust and soluble impurities on the surface. Three portions of washed gangue were prepared and calcined in a muffle furnace at 700°C for 3 h. The gangue was then immersed in 2 M hydrochloric acid for 24 h to remove metallic impurities and some unstable components on the mineral surface. The gangue was then washed with deionized water until the pH value was neutral.

[0057] (2) Silane coupling agent treatment

[0058] The pretreated gangue was immersed in a solution containing approximately 4% 3-(2-aminoethyl)aminopropyltrimethoxysilane. The solution was stirred at room temperature for 48 hours to allow the coupling agent molecules to react with the hydroxyl groups on the gangue surface, forming stable chemical bonds. The solution was then washed again with deionized water and dried to obtain amino-modified gangue (NMCG).

[0059] (3) Preparation of coal gangue-coupled perylene imide composite photocatalytic materials

[0060] First, 3.5 mmol of perylene-3,4,9,10-tetracarboxylic dianhydride, 28.0 mmol of aminopropionic acid, and 18 g of imidazole were heated at 110°C under inert gas for 4 h. The reaction mixture was cooled to room temperature and dispersed in 100 mL of anhydrous ethanol and 300 mL of 2.0 mol / L HCl. The resulting red solid was collected by filtration through a 0.22 μm membrane filter, dried at 70°C, and dissolved in deionized water to prepare 200 mL of perylene diimide (PDI) solution. 5 g of amino-modified coal gangue was slowly added to the PDI solution, followed by 336 μL of triethylamine and stirring for 1 h. Then, 27.3 mL of 4.0 mol / L HCl was added to form PDI supramolecular nanostructures. The solution was then washed with alternating centrifugation using distilled water and anhydrous ethanol until the pH of the washings became neutral. The collected solid was completely dried at 70° C., ground into powder and stored to obtain a modified coal gangue-coupled perylene imide composite material.

[0061] Figure 1 The XRD patterns of the products prepared in Examples 1-3 show the XRD diffraction peak characteristics of different samples. It can be seen that the increase in temperature may lead to changes in the crystal phase or rearrangement of the lattice structure. Figure 1(a) It can be seen that for the calcined modified gangue series samples, as the calcination temperature increases, the intensity and clarity of some diffraction peaks increase, indicating that the order of the crystal structure increases with increasing temperature. Sharper and better crystal diffraction peaks were observed for the calcined modified gangue (MCG-600) calcined at a higher temperature of 600°C, which may indicate an increase in grain growth and purity of the crystal phase. In contrast, the amino modified gangue (NMCG) series samples showed a different diffraction pattern from the modified gangue series ( Figure 1 (a) Amino modification introduces new functional groups, as shown by the XRD diffraction peaks of NMCG-500, NMCG-600, and NMCG-700 samples. Compared to the MCG series samples, these changes in crystallinity are significantly enhanced. These changes may be due to the introduction of amino groups, leading to a rearrangement of the crystal structure or a possible phase transition. Figure 1 (b) XRD patterns of modified gangue-coupled perylene imide composites (PNMCG-500, PMNCG-600, and PMNCG-700) prepared at different temperatures (500°C, 600°C, and 700°C). These patterns reveal a distinct sharp peak at approximately 27°, which may be related to a specific crystalline phase of PDI or its interaction with NMCG. The presence of numerous sharp peaks in the 2θ range of 20°–30° suggests the formation of a new crystalline phase or a more ordered crystal structure with increasing temperature. These results demonstrate the successful preparation of NMCG and PDI composites.

[0062] Figure 2 The infrared spectra of the products prepared in Examples 1 to 3 are shown in Figure 1. MCG-500, MCG-600, and MCG-700 have a wavelength of 3500 cm -1 There is a broad absorption peak near 1000-1100 cm, which may be caused by the stretching vibration of the OH bond, indicating the presence of water or hydroxyl groups. -1 Sharp peaks in the range may indicate the presence of silicon-oxygen bonds (Si-O), a common component in coal gangue. As the temperature increases, the intensity of some peaks decreases, possibly due to the removal or conversion of certain functional groups caused by heat treatment. Compared with the MCG series, amino modification of NMCG-500, NMCG-600, and NMCG-700 may result in some new absorption peaks, especially in the range of 1500-1600 cm -1 range, which may be related to the vibration of amino groups (NH); 3500 cm ⁻1 The broad peak near 1500-1600 cm-1 persists, indicating that even after amino modification, water or hydroxyl groups are still retained. For PNNCG-500, PNNCG-600, and PNNCG-700, the peaks at wavenumbers of 1500-1600 cm-1 are -1The absorption peak between them is more significant, which may be related to the C=O vibration in the PDI structure. The changes in the positions of other peaks may reflect the interaction between PDI and NMCG, especially the possible chemical bond formation or structural changes caused by the interaction. These data further prove that the NMCG and PDI composite material was successfully prepared.

[0063] Figure 3 The following are SEM images of the products prepared in Examples 1-3. Figure 3 It is clearly shown in (a), (b), and (c) that the unmodified gangue particles aggregate together to form dense clusters. The surface morphology is rough and irregular, and there is obvious particle aggregation. Figure 3 Figures (d), (e), and (f) show SEM images of MCG-600 calcined at 600°C. The calcined gangue is more porous than unmodified CG and has a significantly lower density. Particle aggregation is significantly reduced, and the material exhibits a more open and loose structure. Figure 3 Figures (g), (h), and (i) show SEM images of NMCG-600 calcined at 600°C. As can be seen, amino modification further alters the gangue morphology. The particles exhibit a more distinct and separated structure, with increased surface roughness and porosity. This suggests that amino modification enhances particle dispersion, resulting in a more uniform and extended morphology. Figure 3 (j), (k), and (l) show SEM images of NMCG-600 loaded with a large amount of nanofiber PDI. It can be clearly seen that PDI forms a distinct covering on the surface of NMCG-600, making the particle surface more complex and rich. The surface morphology of NMCG-600 after loading with PDI is further changed, and the pore structure is more significant, which helps to improve its performance in catalytic and adsorption applications. The results show that calcination modification and amino modification significantly improve the structure and morphology of coal gangue, while the loading of PDI further enhances its surface properties and pore structure. These morphological changes are crucial to improving the performance of materials in applications such as catalysis and adsorption.

[0064] The adsorption performance of different gangue samples was tested: 30 mg of different gangue materials were weighed into a 50 mL test tube, 30 mL of 20 mg / L Cr (VI) simulated wastewater solution was added, the test tubes were numbered, and placed in a photochemical reactor at room temperature and 180 rpm for 180 min. The sampling time points were set at 0, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200 and 220 min. The adsorption was carried out in a dark environment without light before 120 min to reach adsorption and desorption equilibrium. After 120 min, the xenon lamp was turned on to provide light conditions. After each sampling, the suspension sample was placed in a centrifuge tube and centrifuged at 12000 rpm for 3 min. The supernatant was filtered with a 0.22 μm filter membrane. The Cr (VI) concentration in the filtrate was calculated using the adsorption capacity and removal efficiency using formulas (1) and (2):

[0065] (1)

[0066] (2)

[0067] Among them, q t is the adsorption amount at time t, mg / g; C0 and C t are the initial concentration of the dye and the concentration of the dye at time t, respectively, in mg / L; V is the volume of the dye solution to be adsorbed, in mL; and m is the amount of adsorption material added, in g.

[0068] Figure 4 This is a diagram of the adsorption photocatalytic synergistic performance of the products prepared in Examples 1 to 3. Figure 4(a) shows the removal effect of MCG-500, MCG-600, MCG-700, NMCG-500, NMCG-600 and NMCG-700 on Cr (VI). Under dim light within 120 minutes, the adsorption efficiencies of MCG-500, MCG-600, MCG-700, NMCG-500, NMCG-600 and NMCG-700 were 21.4%, 30.7%, 25.2%, 28.6%, 42.6% and 35.6%, respectively. Adsorption performance reached equilibrium between 80 and 120 minutes. After illumination began at 120 minutes, the photocatalytic efficiencies of MCG-500, MCG-600, MCG-700, NMCG-500, NMCG-600, and NMCG-700 were 29.3%, 49.1%, 43.5%, 47.1%, 67.7%, and 57.1%, respectively. This significant increase in adsorption efficiency under illumination indicates that photocatalysis significantly promotes adsorption. These results indicate that MCG-600 exhibits the best adsorption / photocatalytic performance among the calcined gangue series, while amino-modified samples generally outperform the calcined gangue, with NMCG-600 achieving an adsorption efficiency of 42.6%. As shown in Figure (b), among the three groups of PDI-loaded NMCG samples, NMCG-600 exhibits the highest adsorption efficiency, reaching 58.3%, demonstrating the best adsorption performance of all samples. When illumination began at 120 minutes, the photocatalytic efficiency reached 78.9% within 100 minutes. These results indicate that the introduction of amino groups not only enhances the adsorption capacity of the composite material for Cr(VI), but also promotes electron transfer from PDI to Cr(VI) through its electron donor function, thereby increasing the reduction rate and overall removal efficiency of Cr(VI). Figure 4 Figures (c) and (d) are pseudo-first-order kinetic fitting curves of the photocatalytic performance of different samples, respectively. The figures show the photocatalytic rates of different samples. The kinetic results further verify that the photocatalytic activity of calcined modified coal gangue is enhanced after amino modification, and the photocatalytic activity is further enhanced after loading PDI. PNMCG-600 has the largest kinetic constant among all samples (𝑘=1.72×10 −3 ), the coefficient of determination 𝑅 2 =0.991, indicating that it has the fastest removal rate and highest efficiency for Cr(VI). In addition, NMCG-600 and NMCG-700 also showed high kinetic constants and removal efficiencies, reinforcing the role of amino modification in improving photocatalytic activity.

[0069] Figure 5Figure 3 shows the adsorption-photocatalytic cyclic performance of the modified gangue-coupled perylene imide composites prepared in Examples 1-3. The treatment efficiency fluctuated slightly over the five cycles, with PMCG-600 demonstrating high treatment efficiency and excellent stability. The efficiency reached 78.9% in the first cycle, then decreased slightly over the next five cycles, but remained high overall, reaching 78.4% in the second, 78.2% in the third, 75.4% in the fourth, and 70.4% in the fifth. This indicates that while the performance of PMCG-600 declined somewhat during repeated use, the decrease was minimal, indicating good stability. The performance of PNMCG-500 and PNMCG-700 fluctuated significantly, particularly with PNMCG-700, which exhibited significant performance degradation during repeated use. This may be due to the loss of active sites during use due to the material structure or the degradation of active sites. During continuous use, organic matter or other contaminants may accumulate on the catalyst surface, leading to clogging of active sites and reducing the effective surface area, thereby diminishing the sites available for adsorption and catalysis.

Claims

1. A method for preparing a modified gangue-coupled perylene imide composite material, characterized in that: The following steps are involved: S1, calcining the coal gangue to obtain calcined modified coal gangue; S2, immersing the calcined modified coal gangue in a solution containing a silane coupling agent and stirring to obtain amino-modified coal gangue; S3, adding amino-modified coal gangue to the perylene diimide solution, adding triethylamine, stirring, and then adding hydrochloric acid solution, stirring to obtain a modified coal gangue coupled perylene diimide composite material.

2. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: In S1, the calcination temperature is 500~700℃, and the calcination time is 3~4h.

3. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: S1 specifically comprises: calcining the coal gangue, then immersing it in 2-4 M hydrochloric acid for 20-24 hours, and washing it to obtain calcined modified coal gangue.

4. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, wherein: In S1, the coal gangue is obtained by the following method: the coal gangue is crushed, passed through a 200-400 mesh sieve, and washed with water multiple times.

5. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: S2 is specifically as follows: immersing the calcined modified coal gangue in a solution containing a silane coupling agent with a concentration of 2% to 4%, stirring at room temperature for 24 to 48 hours, washing with water and drying.

6. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: In S2, the silane coupling agent is one of 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-aminopropyltriisopropoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

7. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: In S3, a perylene diimide solution is obtained by the following method: under the protection of inert gas, perylene-3,4,9,10-tetracarboxylic dianhydride, aminopropionic acid and imidazole are mixed and heated at 100-110°C for 4-5 hours; the reaction mixture is cooled to room temperature and then dispersed in anhydrous ethanol and hydrochloric acid solution, and the solid is filtered and collected. The obtained solid is dried and dissolved in water.

8. The method for preparing the modified gangue-coupled perylene imide composite material according to claim 1, characterized in that: In S3, the ratio of amino-modified coal gangue, perylene diimide, and triethylamine is (2~5) g: (1~4) g: (336~834) μL.

9. A modified gangue-coupled perylene imide composite material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the modified gangue-coupled perylene imide composite material according to claim 9 in the adsorption / photocatalytic synergistic treatment of organic pollutants or heavy metal ions.

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