Composite material based on cyclodextrin modification and preparation method and application thereof

Abstract

The invention discloses a cyclodextrin modification-based composite material as well as a preparation method and application thereof, and belongs to the technical field of environmental pollution treatment. The composite material takes a Cu2O hollow sphere as an inner core, and the surface of the Cu2O hollow sphere is coated with a composite shell layer containing amorphous carbon, cyclodextrin and a heavy metal chelating component. The preparation method comprises the following steps: preparing Cu2O / C hollow spheres through a self-template method, carrying out surface activation, then cross-linking with cyclodextrin to construct a molecular recognition layer, and finally introducing a heavy metal chelating component to form the multifunctional composite material. According to the composite material, by constructing an adsorption-catalysis-chelation synergistic system, efficient targeted enrichment, degradation and mineralization of perfluorooctanoic acid (PFOA) are achieved, and meanwhile heavy metal ions are effectively chelated. The technical bottleneck that a traditional catalyst is poor in PFOA selectivity and incomplete in mineralization is broken through, the limitation that a material is single in function is overcome, and the catalyst has wide application prospects in the aspect of cooperative treatment of combined pollution of persistent organic matter and heavy metal.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution control technology, specifically to a composite material based on cyclodextrin modification, its preparation method, and its application. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of persistent organic pollutants with unique chemical structures. Perfluorooctanoic acid (PFOA) is a typical example, exhibiting unique amphiphilicity and extremely strong chemical stability due to its highly polar carboxylic acid group and highly stable carbon-fluorine bond (CF bond energy reaches 116 kcal / mol). These substances are widely used in industries such as textiles, fire-fighting foams, and non-stick coatings, leading to their widespread detection in aquatic environments. Studies have shown that PFOA concentrations in surface water can reach the ng / L to μg / L range, and due to its difficulty in biodegradation, it can persist in the environment for a long time. More seriously, PFOA can accumulate in organisms through the food chain, posing potential harm to the human liver, immune system, and reproductive system. Some regions or organizations have set a lifetime health recommendation limit of 0.004 ppt for PFOA or listed it as a key controlled substance, posing a severe challenge to water treatment technologies.

[0003] Currently, conventional water treatment processes such as coagulation sedimentation and activated carbon adsorption have very limited effectiveness in removing PFOA. While activated carbon adsorption can achieve partial removal of PFOA, it suffers from low adsorption capacity (typically <1 mg / g), difficulty in regeneration, and only achieves phase transfer rather than complete degradation of the pollutant. Biological treatment methods are almost ineffective against PFOA because microorganisms struggle to break its stable CF bonds. In contrast, advanced oxidation processes (AOPs) degrade organic matter by generating highly reactive free radicals (such as hydroxyl radicals ·OH, oxidation potential 2.8 V) and are considered an effective method for treating persistent organic pollutants. However, traditional AOPs such as Fenton oxidation and ozone oxidation are not ideal for treating PFOA, mainly due to the following problems: First, the fluorine atoms in the PFOA molecule have a strong electron-withdrawing effect, reducing the electron cloud density of the carboxylic acid group and making it difficult for free radicals to attack; second, the reaction process often produces short-chain fluorine-containing intermediates, which may be more toxic than PFOA itself; most importantly, the mineralization rate of PFOA by traditional AOPs is usually less than 40%, far from meeting increasingly stringent emission standards.

[0004] Photocatalytic oxidation, as a green and advanced oxidation technology, has shown promising application prospects in the treatment of recalcitrant organic pollutants due to its advantages such as direct solar energy-driven reactions, mild reaction conditions, and no secondary pollution. Traditional photocatalysts, represented by TiO2, can generate highly oxidizing holes and free radicals under ultraviolet light irradiation, enabling the degradation of various organic pollutants. However, TiO2 has significant shortcomings in PFOA treatment: firstly, its wide bandgap (3.2 eV) limits its response to ultraviolet light (wavelength <387 nm), which accounts for only about 5% of the solar spectrum, resulting in low energy utilization; secondly, the TiO2 surface has weak adsorption capacity for hydrophobic PFOA molecules, and the photogenerated electron-hole recombination rate is fast (nanosecond level), leading to low quantum efficiency. More importantly, TiO2 exhibits poor selectivity in PFOA degradation, making it difficult to achieve efficient CF bond breaking, with the final mineralization rate typically not exceeding 30%.

[0005] Cuprous oxide (Cu₂O), as an important p-type semiconductor photocatalyst, possesses a narrow band gap of 2.0–2.2 eV, allowing it to absorb visible light (accounting for 45% of the solar spectrum), giving it a significant advantage in solar energy utilization. Furthermore, Cu₂O has a relatively positive valence band position (approximately +1.5 V vs. NHE), providing sufficient thermodynamic driving force for the oxidative decomposition of organic matter. However, Cu₂O faces severe photocorrosion problems in practical applications: under illumination, Cu… + It is easily oxidized to Cu² + This leads to catalyst deactivation; simultaneously, nano-Cu2O particles are prone to agglomeration due to their high surface energy, resulting in the loss of active sites. While existing technologies can improve the stability of Cu2O through methods such as composite with carbon materials or surface coating, these methods are often complex, costly, and unable to simultaneously address both photocorrosion and agglomeration issues. More importantly, existing Cu2O-based catalysts still lack selectivity in the degradation of PFOA and cannot simultaneously remove common heavy metal pollutants in water (such as Pb). 2+ Cd 2+ (etc.), which limits its practical application value.

[0006] Cyclodextrins are cyclic oligosaccharides linked by α-1,4 glycosidic bonds. β-Cyclodextrin, composed of seven glucose units, has a unique truncated conical structure with a hydrophobic inner cavity and a hydrophilic outer surface. However, natural β-cyclodextrin has high water solubility (up to 18.5 g / 100 mL, 25 °C), making it difficult to use directly as an adsorbent. Furthermore, pure β-cyclodextrin lacks photocatalytic activity and cannot degrade pollutants. Therefore, combining the selectivity of β-cyclodextrin with the oxidation capacity of photocatalysts has become crucial for technological breakthroughs.

[0007] For example, existing patent literature discloses a method for preparing a composite material for removing heavy metals / hydrophobic PPCPs from reclaimed water, involving advanced reclaimed water treatment technology. The method specifically includes the following steps: 1) synthesizing nano-cuprous oxide using a hydrothermal method; 2) using the nano-cuprous oxide prepared in step 1) to synthesize a thermosensitive carboxymethyl cyclodextrin / Cu2O composite material in a one-step process. However, the limited electron conduction in this technology results in less than ideal dispersibility. Another patent literature discloses a defluoridator for water treatment, including raw material components such as calcium salts, polyaluminum salts, polyferric salts, magnesium salts, copper salts, and sodium iminodisuccinate. In this technology, Cu2O is not very effective in improving PFOA degradation efficiency and mineralization rate. Summary of the Invention

[0008] Given that existing composite materials have low degradation efficiency and mineralization rate for perfluorooctanoic acid and cannot simultaneously address the issue of heavy metal ion adsorption, this invention provides a composite material based on cyclodextrin modification, its preparation method, and its application.

[0009] In a first aspect, the present invention provides a composite material based on cyclodextrin modification, the composite material comprising a core and a shell covering the surface of the core. The core comprises a hollow Cu2O sphere; The shell comprises amorphous carbon, cyclodextrin, and heavy metal chelate components. The core comprises hollow Cu2O spheres, which can enhance light capture by modulating Cu. + / Cu 2+ Redox cycle, activate SO4 - · (E 0 =2.5-3.1 V) and O2 - · (E 0 =1.3 V) biradical pathway, collaboratively attacking the high-energy CF bond (bond energy ~116 kcal / mol) in PFOA, gradually degrading it into short-chain carboxylic acid intermediates, and finally mineralizing it into CO2 and F. - .

[0010] The shell layer, comprising amorphous carbon, promotes electron conduction. The inherent p-type conductivity of Cu₂O with negatively charged copper vacancies, combined with the amorphous carbon, enhances electron transport, improves electrochemical reaction kinetics, and strengthens the photocatalyst's absorption of sunlight and visible light, effectively inhibiting Cu₂O photocorrosion. The hydrophobic cavities of cyclodextrin efficiently encapsulate and retain hydrophobic perfluorinated compounds. They can target and adsorb the -CF₂- groups of perfluorooctanoic acid (PFOA) while altering the photocatalyst surface structure, reducing agglomeration due to small particle size, promoting photocatalytic degradation efficiency, and enhancing the material's dispersibility.

[0011] The heavy metal chelating component can regulate the electronic structure of Cu2O through coordination and chelate heavy metal ions, giving the material photocatalytic activity, molecular recognition ability and heavy metal chelation function, providing a new approach for the synergistic treatment of pollutants.

[0012] In one alternative embodiment, the cyclodextrin includes at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0013] In one alternative embodiment, the cyclodextrin is β-cyclodextrin.

[0014] Among them, β-cyclodextrin couples with the Cu2O surface through hydrogen bonding, which not only guides photogenerated holes (h + The directional oxidation of PFOA in its incorporated state further enhances catalytic performance by promoting the formation of electron transfer channels and suppressing photogenerated electron-hole recombination, thereby improving carrier separation efficiency by over 50% and increasing quantum efficiency. Furthermore, the steric hindrance effect of β-CD and surface modification effectively prevent the aggregation of nano-Cu2O, enhancing material stability and photocatalytic cycling performance. This dual stabilizing effect allows the material to maintain structural and catalytic activity stability even after repeated use, demonstrating excellent potential for practical applications.

[0015] In one optional embodiment, the heavy metal chelating component includes at least one of aminocarboxylic acid chelating agents, organophosphonic acid chelating agents, functionalizable natural polymeric chelating agents, and iminodisuccinic acid.

[0016] In one optional embodiment, the aminocarboxylic acid chelating agent includes at least one of ethylenediaminetetraacetic acid, aminotriacetic acid, N,N-diacetic acid of glutamic acid, and methylglycine diacetic acid; the organophosphonic acid chelating agent includes at least one of aminotrimethylphosphonic acid and hydroxyethylidene diphosphonic acid; and the functionalizable natural polymeric chelating agent is selected from at least one of carboxymethyl chitosan and sodium alginate.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned composite material based on cyclodextrin modification, comprising the following steps: S1, Cu2O / C hollow spheres were prepared as the first intermediate using a self-templating method; S2, after the first intermediate is activated with an activator, it is cross-linked with cyclodextrin and a cross-linking agent to obtain the second intermediate; S3, the second intermediate is mixed with a heavy metal chelating agent and a phosphate, and subjected to a hydrothermal reaction to obtain the composite material based on cyclodextrin modification.

[0018] In S1, copper ions first form a stable complex with polydentate carboxylate under alkaline conditions, and then reduce Cu ions to form a stable complex with polydentate carboxylate. 2+ Converted to Cu+ Driven by thermodynamics and following the principle of minimum energy, Cu₂O nanocrystals self-assemble to form hollow spheres. The entire process is a metastable self-transformation of aggregated particles accompanied by local Ostwarld ripening, thus forming a hollow structure. During this process, excess reducing carbon sources are adsorbed onto the surface of the hollow structure due to hydrogen bonding or van der Waals interactions, and after pyrolysis and carbonization, amorphous carbon is formed on the surface of the hollow spheres.

[0019] Subsequently, in S2, the activator activates the carbon layer surface and undergoes a cross-linking reaction with cyclodextrin and a cross-linking agent under hydrothermal conditions. β-cyclodextrin is covalently anchored, giving it molecular recognition capabilities. Its hydrophobic cavity precisely matches the carbon chain length (-CF2- group) of perfluorooctanoic acid (PFOA), achieving selective enrichment. Simultaneously, the inclusion effect of cyclodextrin allows PFOA to closely contact the catalyst's active sites, significantly improving degradation efficiency and mineralization rate, overcoming the bottleneck of traditional non-selective catalysis. On the other hand, cyclodextrin couples with the Cu2O surface through hydrogen bonding, not only guiding photogenerated holes (h... + The directional oxidation of inclusion-state perfluorooctanoic acid also inhibits photogenerated electron-hole recombination through electron transfer channels, thereby improving carrier separation efficiency. In addition, the steric hindrance effect of β-CD effectively prevents the aggregation of nano-Cu2O, enhancing the stability and photocatalytic cycling performance of the prepared material.

[0020] In S3, the heavy metal chelating agent binds to the Cu2O surface through amino-carboxyl bidentate coordination, precisely controlling the electron cloud density of Cu and optimizing the redox potential; its hydrophilic groups modify the material interface, improving dispersibility; at the same time, the negative charge of the heavy metal chelating agent can electrostatically adsorb perfluorooctanoic acid, forming a multi-effect synergistic network of "adsorption-degradation-chelation", achieving efficient coupling of material structural stability and catalytic function.

[0021] In an optional embodiment, in S1, the self-templating method involves mixing a copper source, a structure-directing agent, a complexing agent, an alkali source, a reducing carbon source, and water, reacting the mixture, and then calcining it to obtain a first intermediate.

[0022] In an optional embodiment, in S1, the copper source includes at least one of copper chloride, copper sulfate, copper nitrate, and copper acetate.

[0023] In an optional embodiment, in S1, the structure directing agent includes at least one of polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide-polypropylene oxide block copolymer, polyvinyl alcohol, and hexadecyltrimethylammonium bromide.

[0024] In an alternative embodiment, in S1, the complexing agent is a polydentate carboxylate.

[0025] In one alternative embodiment, the polydentate carboxylate comprises citrate and / or tartrate.

[0026] In one alternative embodiment, the citrate cation includes sodium ions and / or potassium ions.

[0027] In one optional embodiment, the citrate comprises at least one of disodium citrate dihydrate, anhydrous trisodium citrate, trisodium citrate dihydrate, trisodium citrate pentahydrate, tripotassium citrate, and potassium citrate monohydrate.

[0028] In an optional embodiment, in S1, the alkali source includes sodium hydroxide and / or potassium hydroxide.

[0029] In an optional embodiment, in S1, the reducing carbon source includes at least one of glucose, fructose, galactose, lactose, and maltose.

[0030] In one optional embodiment, in S1, the reaction temperature is 70~80°C and the time is 20~40 min.

[0031] In one optional embodiment, in S1, the calcination temperature is 160~190℃, the time is 3~5h, and the heating rate is 5~10℃ / min.

[0032] In an optional embodiment, in S1, the molar ratio of hydroxide ions in the copper source to the reducing carbon source, complexing agent, and alkaline source is 1:(1.4~1.7):(0.20~0.22):(4~5).

[0033] In one optional embodiment, in S1, the ratio of the structure-directing agent to water is (10~15):1, in g:L.

[0034] In one optional embodiment, in S1, the ratio of the copper source to water is 1:(10~14), with units of mmol:mL.

[0035] In one alternative embodiment, step S1 further includes washing and drying steps before calcination.

[0036] In one optional embodiment, the washing method is washing with ethanol and water; In one optional embodiment, the drying method is vacuum drying at a temperature of 60-80°C for 5-8 hours.

[0037] In one optional embodiment, in S2, the ratio of the first intermediate to the activator is 1:30~100, in g:mL.

[0038] In one optional implementation, in S2, the ratio of the first intermediate to water is 1:50~150, in g:mL.

[0039] In one optional embodiment, in S2, the ratio of cyclodextrin to crosslinking agent is 1:0.6~2.5, in g:mL.

[0040] In an optional embodiment, in S2, the activator comprises 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide.

[0041] In an optional embodiment, in S2, the crosslinking agent is selected from at least one of epoxy compounds and dialdehyde compounds.

[0042] In one optional embodiment, the epoxy compound is selected from at least one of epichlorohydrin and ethylene glycol diglycidyl ether; the dialdehyde compound is selected from at least one of glutaraldehyde and genipin.

[0043] In one optional embodiment, in S2, the activation treatment time is 1.5 to 3 hours, and the pH during the activation treatment is 6.5 to 7.5.

[0044] In one optional embodiment, in S2, the crosslinking reaction is carried out at a temperature of 60-70°C for 2-3 hours.

[0045] In an alternative embodiment, step S2 further includes a drying step after the crosslinking reaction.

[0046] In one optional embodiment, the drying method is vacuum drying at a temperature of 50-70°C for 2-4 hours.

[0047] In one optional embodiment, in S3, the mass ratio of the second intermediate, the heavy metal chelating component, and the phosphate is 1~3:1~3:1.

[0048] In one optional implementation, in S3, the ratio of the second intermediate to water is 1:30~100, in g:mL.

[0049] In an optional embodiment, in S3, the phosphate includes at least one of potassium dihydrogen phosphate, disodium hydrogen phosphate, and sodium tripolyphosphate.

[0050] In one optional embodiment, in S3, the temperature of the hydrothermal reaction is 130°C to 150°C, and the time is 3 to 5 hours.

[0051] In an alternative implementation, S3 further includes drying.

[0052] In one optional embodiment, the drying method is vacuum drying at a temperature of 60-80°C for 5-8 hours.

[0053] Thirdly, the present invention also provides the application of the above-mentioned cyclodextrin-modified composite material or the cyclodextrin-modified composite material prepared by the above-mentioned preparation method in the treatment of wastewater and / or sludge containing perfluorinated and polyfluoroalkyl substances and / or heavy metal ions.

[0054] In one alternative embodiment, the application includes the following steps: adding the cyclodextrin-modified composite material to the wastewater or sludge to be treated and carrying out a light-protected adsorption reaction.

[0055] In one alternative embodiment, the degradation reaction is further performed under light irradiation after the light-shielded adsorption reaction.

[0056] In one optional embodiment, the light-shielded adsorption reaction takes 0.5 to 1 hour.

[0057] In one alternative embodiment, the wavelength of the illumination condition is visible light with a wavelength of ≥ 420 nm.

[0058] In one alternative embodiment, the degradation reaction takes ≥3 hours.

[0059] In one optional embodiment, the degradation reaction takes 3 to 6 hours.

[0060] In one optional embodiment, the dosage of the cyclodextrin-modified composite material is 50~500 mg / L.

[0061] In one alternative embodiment, the initial concentration of perfluorinated and polyfluoroalkyl substances in the wastewater and / or sediment is ≥1 mg / L.

[0062] In one optional embodiment, the initial concentration of heavy metal ions in the wastewater and / or sediment is ≥1 mg / L.

[0063] The technical solution of this invention has the following advantages: 1. This invention provides a composite material based on cyclodextrin modification, which integrates a Cu2O hollow sphere structure layer, amorphous carbon, and cyclodextrin and heavy metal chelating components to construct an "adsorption-catalysis synergistic system." This system overcomes the challenges of mass transfer limitations and incomplete mineralization in the degradation of perfluorinated and polyfluoroalkyl substances. It achieves the synergistic effect of "targeted enrichment-efficient degradation-deep mineralization" of perfluorinated and polyfluoroalkyl substances and "selective adsorption" of heavy metals on the same material. This solves the problem of the single function of traditional materials and maintains high efficiency in complex matrices (such as industrial wastewater and sludge), providing a new strategy for the treatment of persistent pollutants.

[0064] 2. The method for preparing composite materials based on cyclodextrin modification provided by this invention solves the problems of light absorption and carrier separation by preparing Cu2O hollow sphere precursors through a self-templating method; constructing a conductive carbon layer through in-situ carbonization improves electron conduction and inhibits Cu2O photocorrosion; imparting molecular recognition ability to the material through covalent grafting of cyclodextrin, achieving selective enrichment of PFOA; and finally introducing a heavy metal chelating agent, which can both regulate the electronic structure of Cu through coordination and chelate heavy metal ions. This integrated design concept of "adsorption-catalysis-stabilization" effectively solves the key problems of poor selectivity, incomplete mineralization, and easy material deactivation in traditional technologies, providing an innovative solution for the efficient removal of PFOA from wastewater or sludge.

[0065] 3. The application of the cyclodextrin-modified composite material provided by this invention in the photocatalytic degradation of perfluorinated and polyfluoroalkyl substances in wastewater and / or the adsorption of heavy metal ions in wastewater. The composite material has the functions of high-efficiency adsorption, targeted degradation and heavy metal chelation, and can maintain the stability of structure and catalytic activity after multiple uses, and has good potential for practical application. Attached Figure Description

[0066] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0067] Figure 1 This is a transmission electron microscope (TEM) image of the Cu2O hollow spheres prepared in Example 1. Figure 2 This is a scanning electron microscope image of the cyclodextrin-modified composite material prepared in Example 1; Figure 3 The image shows the X-ray diffraction pattern of the cyclodextrin-modified composite material prepared in Example 1. Detailed Implementation The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0068] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0069] Example 1 This embodiment provides a composite material based on cyclodextrin modification, and its specific preparation steps and operating parameters are as follows: (1) Weigh 8.5 mmol CuCl2·2H2O and 1 g polyvinylpyrrolidone (average molecular weight of 300,000) and dissolve them in 90 mL of deionized water. Stir for 15 min until the solution is completely dissolved. Then add a mixed solution of 1.8 mmol disodium citrate dihydrate and 0.035 mol NaOH and continue stirring for 10 min until the mixture is homogeneous. Finally, add 12.5 mmol glucose, heat to 70 °C, and react for 30 min until the reaction is complete. After cooling, filtration, and drying, transfer the product to a muffle furnace and calcine it at 180 °C under a nitrogen atmosphere at a heating rate of 5 °C / min for 3 h. After cooling naturally to room temperature, wash the product several times with water and ethanol, and dry it under vacuum at 70 °C for 6 h to obtain the target product Cu2O / C hollow sphere material (i.e., the first intermediate). (2) Disperse 2g of the first intermediate in 200mL of deionized water, sonicate for 10min, and add 0.1mol / L of EDC (C8H2O). 17 50 mL each of N3•HCl and NHS(C4H5NO3) were added and magnetically stirred for 2 h while maintaining pH=6.5. 4 g of β-cyclodextrin and 10 mL of epichlorohydrin were added, and the mixture was sonicated for 15 min. Then, the mixture was hydrothermally reacted in a 60 °C water bath for 2.5 h. The pH was adjusted to 7.0. The product was washed several times with deionized water and ethanol, filtered, and then vacuum dried at 70 °C for 3 h to obtain the second intermediate Cu2O / C / β-cyclodextrin. (3) Weigh 1.5g of the second intermediate, 1.5g of iminodisuccinic acid and 0.5g of potassium dihydrogen phosphate and disperse them in 50mL of deionized water. Sonicate until the mixture is completely dissolved. Then transfer it to a 100mL hydrothermal reactor and react it hydrothermally at 150℃ for 3h. Cool it naturally to room temperature, wash it several times with deionized water and ethanol, and vacuum dry it at 70℃ for 6h to obtain the composite material based on cyclodextrin modification.

[0070] The structure of the cyclodextrin-modified composite material prepared in this embodiment was characterized, and the results are as follows: Depend on Figure 1 As can be seen, the first intermediate Cu2O / C has a clear hollow sphere structure with obvious shells, proving that Cu2O hollow spheres were successfully synthesized.

[0071] Depend on Figure 2It is evident that the material exhibits a multi-level structural feature. The material is composed of irregular spherical particles with a uniformly rough texture on the surface; nano-protrusions are randomly distributed on the surface; and clusters are observed in local areas. The spherical particles with this morphological feature are characteristic of hollow Cu2O spheres, the rough texture corresponds to the pyrolysis carbonization process, and the surface protrusions / pores correspond to the modification processes in steps (2) and (3).

[0072] Figure 3 The XRD pattern of the cyclodextrin-modified composite material prepared in this embodiment shows obvious diffraction peaks at 2θ = 29.5°, 36.4°, 42.3°, 61.4°, and 73.6°, corresponding to the (110), (111), (200), (220), and (311) crystal planes of cubic Cu₂O (JCPDS No. 05-0667), respectively. The peaks are sharp and free of impurities, indicating that Cu₂O has good crystallinity. The grain size of the (111) crystal plane (2θ = 36.4°, half-width at half-maximum 0.32°) is calculated to be approximately 24.7 nm using the Scherrer equation, indicating that... Figure 1 The microsphere structure formed was consistent. A broadened diffuse peak (d=0.38 nm) was observed at 2θ=24.5°, which was attributed to amorphous carbon and corresponded to the product after carbonization of excess glucose at 180°C in step (1). Its amorphous properties can reduce light scattering and promote electron conduction. No characteristic peaks of CuO (2θ=35.5°, 38.7°) or elemental Cu (2θ=43.3°) were detected, confirming that amorphous carbon effectively inhibited the oxidation or reduction of Cu2O and ensured the stability of the catalyst. In addition, the amorphous organic components of β-cyclodextrin and iminodisuccinic acid did not produce obvious diffraction peaks, indicating that they were uniformly modified on the material surface through covalent grafting or coordination without destroying the crystal structure of Cu2O. The above results show that the target product successfully constructed a "cubic phase Cu2O-amorphous carbon" core-shell structure and achieved surface loading of organic functional molecules, providing a structural basis for subsequent photocatalytic activity and selectivity.

[0073] Example 2 This embodiment provides a composite material based on cyclodextrin modification. Its specific preparation steps and operating parameters are basically the same as those in Example 1. The only difference is that the β-cyclodextrin in step (2) is replaced with an equal mass of γ-cyclodextrin.

[0074] Example 3 This embodiment provides a composite material based on cyclodextrin modification. Its specific preparation steps and operating parameters are basically the same as those in Example 1. The only difference is that iminodisuccinic acid in step (3) is replaced with an equal mass of aminotrimethylphosphonic acid.

[0075] Example 4 This embodiment provides a composite material based on cyclodextrin modification, and its specific preparation steps and operating parameters are as follows: (1) Weigh 8.1 mmol CuSO4•2H2O and 1.8 g polyvinylpyrrolidone and dissolve them in 120 mL of deionized water. Stir for 15 min until the solution is completely dissolved. Then add a mixed solution of 1.8 mmol potassium sodium tartrate tetrahydrate and 40 mmol KOH and continue stirring for 10 min to mix evenly. Finally, add 14.0 mmol fructose, heat to 80 °C, and react for 20 min until the reaction is complete. After cooling, filtration, and drying, transfer the product to a muffle furnace and calcine it under a nitrogen atmosphere. Heat to 160 °C at a heating rate of 10 °C / min and keep it at that temperature for 4 h. Cool naturally to room temperature. Wash the product several times with water and ethanol, and dry it under vacuum at 80 °C for 5 h to obtain the target product Cu2O / C hollow sphere material (first intermediate). (2) Disperse 1g of the first intermediate in 200mL of deionized water, sonicate for 15min, and add 0.1mol / L of EDC (C8H2O). 17 50 mL each of N3•HCl and NHS(C4H5NO3) were added and magnetically stirred for 3 h while maintaining pH = 7.5. 4 g of β-cyclodextrin and 6 mL of glutaraldehyde were added, and the mixture was sonicated for 15 min. Then, the mixture was hydrothermally reacted in a 70 °C water bath for 2 h. The pH was adjusted to 7.0. The product was washed several times with deionized water and ethanol, filtered, and then vacuum dried at 50 °C for 4 h to obtain the second intermediate Cu2O / C / β-cyclodextrin. (3) Weigh 1g of the second intermediate, 0.5g of ethylenediaminetetraacetic acid and 0.5g of disodium hydrogen phosphate and disperse them in 50mL of deionized water. Sonicate until the mixture is completely dissolved. Then transfer it to a 100mL hydrothermal reactor and react it hydrothermally at 130℃ for 5h. After cooling naturally to room temperature, wash it several times with deionized water and ethanol, and vacuum dry it at 80℃ for 5h to obtain the composite material based on cyclodextrin modification.

[0076] Example 5 This embodiment provides a composite material based on cyclodextrin modification, and its specific preparation steps and operating parameters are as follows: (1) Weigh 9.3 mmol CuNO3•H2O and 1 g polyethylene glycol and dissolve them in 100 mL of deionized water. Stir for 15 min until the solution is completely dissolved. Then add a mixed solution of 2 mmol trisodium citrate pentahydrate and 45 mmol NaOH and continue stirring for 10 min until the mixture is uniform. Finally, add 15.8 mmol lactose, heat to 75 °C, and react for 40 min until the reaction is complete. After cooling, filtration, and drying, transfer the product to a muffle furnace and calcine it under a nitrogen atmosphere. Heat to 190 °C at a heating rate of 8 °C / min and keep it at that temperature for 5 h. Cool naturally to room temperature. Wash the product several times with water and ethanol, and dry it under vacuum at 60 °C for 8 h to obtain the target product Cu2O / C hollow sphere material (first intermediate).

[0077] (2) Dissolve 3g of the first intermediate in 200 mL of deionized water, sonicate for 20 min, and add 0.1 mol / L of EDC (C8H2O). 17 50 mL each of N3•HCl and NHS(C4H5NO3) were added and magnetically stirred for 1.5 h while maintaining pH 7.0. 3 g of β-cyclodextrin and 1.8 mL of epichlorohydrin were added, and the mixture was sonicated for 15 min. Then, the mixture was hydrothermally reacted in a 65 °C water bath for 3 h. The pH was adjusted to 7.0. The product was washed several times with deionized water and ethanol, filtered, and then vacuum dried at 60 °C for 2 h to obtain the second intermediate Cu2O / C / β-cyclodextrin. (3) Weigh 0.5g of the second intermediate, 1g of aminotrimethylphosphonic acid and 0.5g of sodium tripolyphosphate and disperse them in 50mL of deionized water. Sonicate until the mixture is completely dissolved. Then transfer it to a 100mL hydrothermal reactor and react it hydrothermally at 140℃ for 4h. After cooling naturally to room temperature, wash it several times with deionized water and ethanol, and dry it under vacuum at 60℃ for 8h to obtain the composite material based on cyclodextrin modification.

[0078] Comparative Example 1 This comparative example provides a commercially available pure Cu2O material, purchased from Shanghai Yanbei New Material Technology Co., Ltd., model number: YB-FM-Cu2O.

[0079] Comparative Example 2 This comparative example provides a Cu2O / C hollow sphere material, the preparation method of which is basically the same as that of Example 1, except that steps (2) and (3) are omitted.

[0080] Comparative Example 3 This comparative example provides a Cu2O / C / β-cyclodextrin material, the preparation method of which is basically the same as that of Example 1, except that step (3) is omitted.

[0081] Comparative Example 4 This comparative example provides a Cu2O / C / β-cyclodextrin material, the preparation method of which is basically the same as that of Example 1, except that step (2) is omitted.

[0082] Comparative Example 5 This comparative example provides a composite material whose raw materials are basically the same as those in Example 1. The preparation method is a one-step method, which is basically the same as step (3) in Example 1. Specifically, all parts by weight of the raw materials are dispersed in 50 mL of deionized water and sonicated until the mixture is completely dissolved to obtain the composite material.

[0083] Experiment Example 1: PFOA Degradation and Mineralization Experiment A PFOA aqueous solution with an initial concentration of 10 mg / L was prepared as simulated wastewater. 100 mL of this solution was taken and placed in a series of photocatalytic reaction bottles, followed by the addition of 20 mg of the materials from each example and comparative example to each bottle. The reaction bottles were placed in a dark chamber and magnetically stirred for 40 min to reach adsorption-desorption equilibrium. Subsequently, the photocatalytic reaction was carried out at room temperature under simulated sunlight conditions, with continuous magnetic stirring. Samples were taken after 3 h of reaction, filtered through a 0.22 μm filter membrane, and the PFOA concentration was determined by high-performance liquid chromatography-tandem mass spectrometry (referring to "Determination of Perfluorooctyl Sulfonic Acid and Perfluorooctanoic Acid and Their Salts in Water Quality: Isotope Dilution / Liquid Chromatography-Triple Quadrupole Mass Spectrometry" HJ 1333—2023). The fluoride ion concentration was determined by ion chromatography (referring to "Determination of Inorganic Anions (F) in Water Quality"). - Cl - NO 2- ,Br - NO 3- PO4 3- SO3 2- SO4 2- (Determination of ions by ion chromatography, HJ 84-2016).

[0084] The formula for calculating the defluorination rate (%) is as follows: Defluorination rate (%) = (fluoride ions F measured after the reaction) - Concentration / Theoretically, F produced by complete mineralization of PFOA - (ion concentration) ×100% Among them, the F that can be theoretically produced by the complete mineralization of PFOA - The ion concentration is calculated as follows: (1) Determine the initial PFOA concentration: Given: initial concentration C0 = 10 mg / L; (2) Determine the molecular structure and molecular weight of PFOA: PFOA molecular formula: C8HF 15O2, with a molecular weight of 414 g / mol; each PFOA molecule contains 15 fluorine atoms, and the total mass of the 15 fluorine atoms is M. F = 19 × 15 = 285 g / mol; (3) Calculate the F that can be theoretically produced by the complete mineralization of PFOA. - Ion concentration: If 10 mg / L of PFOA is 100% completely mineralized, it can produce 10 mg / L × (285 / 414) = 6.88 mg / L of F. - ion.

[0085] The experimental results are shown in Table 1.

[0086] Table 1. Comparison of photocatalytic degradation and defluorination performance of different materials (reaction time 3h)

[0087] As shown in Table 1, the materials of Examples 1-5 of this invention exhibit excellent degradation and mineralization capabilities for PFOA, with PFOA removal rates all exceeding 95% and defluorination rates all exceeding 55%. The PFOA removal rate of Example 1 is approximately 1.46 times higher than that of Comparative Example 1 (pure Cu2O), which is attributed to the synergistic enhancement of mass transfer and photocatalysis by its hierarchical structure. Examples 1-5 of this invention show a significant advantage in mineralization degree (indicated by defluorination rate) compared to the materials of Comparative Examples 1-5, indicating that they can more thoroughly disrupt CF bonds.

[0088] Experiment Example 2: Heavy Metal Adsorption Experiment Formulating Pb 2+ Cd 2+ Cu 2+ A mixed heavy metal solution with an initial concentration of 10 mg / L was prepared. 50 mL of this solution was placed in an Erlenmeyer flask, and 25 mg of each material from the examples and comparative examples was added. The solution was shaken in a constant temperature shaker (25°C, 150 rpm) for 1 hour in the dark to ensure adsorption equilibrium. After filtration, the concentration of remaining heavy metal ions in the solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) (referring to "Determination of 22 Metallic Elements in Solid Waste by Inductively Coupled Plasma Atomic Emission Spectrometry"). The results are shown in Table 2.

[0089] Table 2 Adsorption performance of materials for heavy metal ions

[0090] As shown in Table 2, the material of this invention exhibits strong adsorption capacity for a variety of heavy metal ions, especially for Pb. 2+ The adsorption rates are all higher than 98%, which is due to the excellent chelating performance of the heavy metal chelating agent and the synergistic effect of the material surface.

[0091] Experiment Example 3: Reuse Experiment The materials obtained after filtration following the reactions in each example and comparative example were washed with deionized water, dried under vacuum at 60°C, and then subjected to catalytic degradation and heavy metal ion adsorption again, using the same method as in Experimental Example 1. The cycle test was performed three times, and the performance data after the third cycle is shown in the table below. Detailed data are shown in Tables 3 and 4.

[0092] Table 3 Comparison of PFOA degradation and defluorination performance of different materials after repeated use

[0093] Table 4. Comparison of heavy metal ion adsorption performance of different materials after repeated use

[0094] As shown in Tables 3 and 4, the composite materials prepared in Examples 1-5 of the present invention still maintain high PFOA removal rates and heavy metal ion adsorption rates after being used three times, while the materials in Comparative Examples 1-5 are all lower. This indicates that the composite materials based on cyclodextrin modification provided by the present invention can maintain the stability of structure and catalytic activity after multiple uses and have good potential for practical application.

[0095] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite material based on cyclodextrin modification, characterized in that, The composite material includes a core and a shell covering the surface of the core. The core comprises a hollow Cu2O sphere; The shell comprises amorphous carbon, cyclodextrin, and heavy metal chelate components.

2. The composite material based on cyclodextrin modification according to claim 1, characterized in that, The cyclodextrin includes at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and optionally β-cyclodextrin; And / or, the heavy metal chelating component includes at least one of aminocarboxylic acid chelating agents, organophosphonic acid chelating agents, functionalizable natural polymeric chelating agents, and iminodisuccinic acid; Optionally, the aminocarboxylic acid chelating agent includes at least one of ethylenediaminetetraacetic acid, aminotriacetic acid, N,N-diacetic acid of glutamic acid, and methylglycine diacetic acid; the organophosphonic acid chelating agent includes at least one of aminotrimethylphosphonic acid and hydroxyethylidene diphosphonic acid; and the functionalizable natural polymeric chelating agent is selected from at least one of carboxymethyl chitosan and sodium alginate.

3. A method for preparing a composite material based on cyclodextrin modification as described in claim 1, characterized in that, Includes the following steps: S1, Cu2O / C hollow spheres were prepared as the first intermediate using a self-templating method; S2, after the first intermediate is activated with an activator, it is cross-linked with cyclodextrin and a cross-linking agent to obtain the second intermediate; S3, the second intermediate is mixed with a heavy metal chelating agent and a phosphate, and subjected to a hydrothermal reaction to obtain the composite material based on cyclodextrin modification.

4. The method for preparing the composite material based on cyclodextrin modification according to claim 3, characterized in that, In S1, the self-templating method involves mixing a copper source, a structure-directing agent, a complexing agent, an alkali source, a reducing carbon source, and water, reacting the mixture, and then calcining it to obtain the first intermediate.

5. The method for preparing the composite material based on cyclodextrin modification according to claim 4, characterized in that, In S1, the copper source includes at least one of copper chloride, copper sulfate, copper nitrate, and copper acetate; And / or, in S1, the structure directing agent includes at least one of polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide-polypropylene oxide block copolymer, polyvinyl alcohol, and hexadecyltrimethylammonium bromide; And / or, in S1, the complexing agent is a polydentate carboxylate; optionally, the polydentate carboxylate includes citrate and / or tartrate. More preferably, the cations of the citrate include sodium ions and / or potassium ions; Alternatively, the citrate includes at least one of disodium citrate dihydrate, anhydrous trisodium citrate, trisodium citrate dihydrate, trisodium citrate pentahydrate, tripotassium citrate, and potassium citrate monohydrate; And / or, in S1, the alkali source includes sodium hydroxide and / or potassium hydroxide; And / or, in S1, the reducing carbon source includes at least one of glucose, fructose, galactose, lactose, and maltose; And / or, in S1, the reaction temperature is 70~80℃ and the time is 20~40min; And / or, in S1, the calcination temperature is 160~190℃, the time is 3~5h, and the heating rate is 5~10℃ / min.

6. The method for preparing the composite material based on cyclodextrin modification according to claim 4, characterized in that, In S1, the molar ratio of hydroxide ions in the copper source, reducing carbon source, complexing agent, and alkaline source is 1:(1.4~1.7):(0.20~0.22):(4~5); And / or, in S1, the ratio of the structure-directing agent to water is (10~15):1, in g:L; And / or, in S1, the ratio of the copper source to water is 1:(10~14), in mmol:mL.

7. The method for preparing the composite material based on cyclodextrin modification according to claim 3, characterized in that, In S2, the ratio of the first intermediate to the activator is 1:30~100, in g:mL; And / or, in S2, the ratio of the first intermediate to water is 1:50~150, in g:mL; And / or, in S2, the ratio of cyclodextrin to crosslinking agent is 1:0.6~2.5, in g:mL; And / or, in S2, the activator comprises 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; And / or, in S2, the crosslinking agent is selected from at least one of epoxy compounds and dialdehyde compounds; Optionally, the epoxy compound is selected from at least one of epichlorohydrin and ethylene glycol diglycidyl ether; the dialdehyde compound is selected from at least one of glutaraldehyde and genipin. And / or, in S2, the activation treatment time is 1.5~3h, and the pH during the activation treatment is 6.5~7.5; And / or, in S2, the crosslinking reaction is carried out at a temperature of 60~70°C for 2~3 hours.

8. The method for preparing the composite material based on cyclodextrin modification according to claim 3, characterized in that, In S3, the mass ratio of the second intermediate, the heavy metal chelating component, and the phosphate is 1~3:1~3:1; And / or, in S3, the ratio of the second intermediate to water is 1:30~100, in g:mL; And / or, in S3, the phosphate includes at least one of potassium dihydrogen phosphate, disodium hydrogen phosphate, and sodium tripolyphosphate; And / or, in S3, the hydrothermal reaction is carried out at a temperature of 130°C to 150°C for a time of 3 to 5 hours.

9. The application of the cyclodextrin-modified composite material according to claim 1 or 2, or the cyclodextrin-modified composite material prepared by any one of claims 3-8, in the treatment of wastewater and / or sludge containing perfluorinated and polyfluoroalkyl substances and / or heavy metal ions.

10. The application according to claim 9, characterized in that, The process includes the following steps: adding the cyclodextrin-modified composite material to the wastewater or sludge to be treated and carrying out a light-protected adsorption reaction; Optionally, the degradation reaction under light irradiation is included after the light-shielded adsorption reaction; Optionally, the light-shielded adsorption reaction takes 0.5 to 1 hour; Alternatively, the wavelength of the light under the illumination condition is visible light ≥ 420 nm; More preferably, the degradation reaction takes ≥3 hours, or preferably 3 to 6 hours; And / or, the dosage of the composite material based on cyclodextrin modification is 50~500 mg / L; And / or, the initial concentration of perfluorinated and polyfluoroalkyl substances in the wastewater and / or sediment is ≥1 mg / L; And / or, the initial concentration of heavy metal ions in the wastewater and / or sediment is ≥1 mg / L.

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