Carbon quantum dot for synchronous detection and adsorption treatment of bisphenol A, bio-based composite membrane and preparation and application of carbon quantum dot and bio-based composite membrane

Abstract

The invention discloses a carbon quantum dot for synchronous detection and adsorption treatment of bisphenol A. The carbon quantum dot is prepared by performing solvothermal reaction on morpholine and / or a morpholine derivative and polyethylene glycol to obtain a precursor solution, and then performing heating reaction on the precursor solution and an amino imidazole compound, the morpholine and / or the morpholine derivative comprises at least one of morpholine, 4-acetylmorpholine, 4-aminomorpholine and morpholine-4-yl acetic acid. The carbon quantum dot provided by the invention has a CO2 responsive function, has a linear fluorescence cluster extinguishing phenomenon on bisphenol A, can provide active sites to enhance the adsorption performance of a membrane, and can be used as a detection material and an adsorption material of bisphenol A. The bio-based composite film prepared from the carbon quantum dots can realize efficient adsorption treatment and real-time reliable monitoring in the aspect of bisphenol A pollution treatment application of industrial wastewater, also has the advantages of wide raw material source, low cost and environmental protection, and has wide prospects in the aspects of economic, environmental and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon quantum dots, specifically to CO2-responsive carbon quantum dots that can be used to detect bisphenol A and can also be used on bisphenol A adsorption treatment materials, as well as a bio-based composite membrane containing the CO2-responsive carbon quantum dots, and its application in the detection and treatment of bisphenol A pollutants. Background Art

[0002] Bisphenol A (BPA) is a key raw material in the production of polymer materials such as polycarbonate plastics and epoxy resins. It is also found in a wide range of daily necessities and industrial products, including food and beverage packaging, baby bottles, sports bottles, eyeglass lenses, and medical devices. As BPA production has steadily increased in recent years, the pollution it brings has become increasingly serious.

[0003] From an environmental perspective, BPA is difficult to degrade in the natural environment and persists for long periods in media like soil and water, causing damage to ecosystems. Specifically, even low concentrations of BPA can interfere with the endocrine systems of aquatic organisms, affecting the growth, development, and reproduction of fish, shellfish, and other organisms, leading to population declines. Within organisms, BPA is bioaccumulative, accumulating through the food chain. Concerning human health, BPA is structurally similar to estrogen in the human endocrine system, making it an endocrine disruptor that affects the development and function of the reproductive, nervous, and immune systems. Therefore, the detection and treatment of BPA are key to addressing BPA contamination.

[0004] Currently, the detection technologies for bisphenol A mainly include atomic absorption spectrometry, high-performance liquid chromatography, gas chromatography-mass spectrometry and chemical titration. These detection technologies generally have problems such as requiring expensive large-scale instruments, cumbersome and complex detection steps, and high professional requirements for operators. In addition, it is difficult to achieve real-time monitoring during the pollution treatment process.

[0005] With the development of optoelectronic and sensing technologies, some new carbon nanomaterials have emerged in the detection of organic pollutants. Among them, carbon quantum dots have shown advantages in the field of analytical detection due to their good biocompatibility, high fluorescence stability, and ease of surface functionalization. For example, some studies have used carbon quantum dots to modify glassy carbon electrodes, showing significant enrichment and detection performance for the analytes. Although research on carbon quantum dot-related technologies in the detection field is deepening, the detection of bisphenol A still faces challenges in cost control, application portability, and stability optimization before practical application, and further exploration and breakthroughs are urgently needed. Summary of the Invention

[0006] In order to address the shortcomings of bisphenol A, such as complicated detection and difficulty in real-time monitoring, the present invention develops a carbon quantum dot with CO2 response characteristics, which can realize the simultaneous detection and adsorption treatment of bisphenol A.

[0007] To achieve the above-mentioned purpose, the carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A of the present invention are prepared by solvent thermal reaction of morpholine and / or morpholine derivatives with polyethylene glycol to obtain a precursor solution, which is then heated with an aminoimidazole compound to react;

[0008] The morpholine and / or morpholine derivatives include at least one of morpholine, 4-acetylmorpholine, 4-aminomorpholine, and morpholin-4-yl acetic acid.

[0009] As a limitation of the above technical solution, the polyethylene glycol includes at least one of polyethylene glycol 200 and polyethylene glycol 400; and / or the aminoimidazole compound includes at least one of 2-aminoimidazole, 4-amino-5-imidazolecarboxamide, 5-azabenzimidazole, and 1-(1H-imidazole-1-carboxylimide)-1H-imidazole.

[0010] As a limitation of the above technical solution, the molar ratio of morpholine and / or morpholine derivatives to polyethylene glycol is 3:1-9; and / or the temperature of the solvent thermal reaction is 180° C.-220° C. and the time is 8-12 hours.

[0011] As a limitation of the above technical solution, in the precursor solution, the ratio of the total mass of the solute morpholine, morpholine derivatives and polyethylene glycol to the solvent water is 1g:20~40mL; and / or, the mass ratio of the precursor solution to the aminoimidazole compound is 4:1~10, the heating reaction temperature is 40~80℃, and the time is 0.5~2h.

[0012] As a limitation of the above technical solution, the carbon quantum dots are CO2-responsive carbon quantum dots.

[0013] The preparation of carbon quantum dots of the present invention is divided into two steps. The first step is to form a precursor through hydrogen bonding between morpholine, morpholine derivatives and polyethylene glycol under hydrothermal action. The second step is to post-modify the precursor with aminoimidazole compounds to generate a carbon quantum dot material with CO2 response characteristics.

[0014] The carbon quantum dots of the present invention have the following outstanding advantages: First, the rich functional groups such as morpholine, amine, hydroxyl, carboxyl, amide, etc. possessed by the precursor are utilized as active sites of the composite material to improve the adsorption performance. Second, amino imidazole compounds are selected as raw materials, which not only retains the imidazole group that can act under CO2 stimulation, but also introduces an amino group that can enhance the CO2 response, which is beneficial to the dynamic regulation of the material pore process, which only involves the passage and discharge of CO2 gas, does not produce secondary pollution, and has low energy consumption. Third, the post-modification method is utilized in the material preparation process, that is, the precursor is first prepared, and then the CO2 responsive functional group is connected to the precursor by a modification method, so that the CO2 responsive functional group does not undergo the high temperature and high pressure process of the solvent thermal reaction, and the characteristics of the functional group are retained as completely as possible. Fourth, the photoluminescence characteristics of carbon quantum dots are utilized to achieve synchronous monitoring during the pollutant treatment process and to achieve real-time control of the reaction process.

[0015] At the same time, the present invention also provides the application of carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A as described above, that is, as an effective substance for detecting and / or adsorbing bisphenol A, for preparing detection materials and adsorption materials for bisphenol A.

[0016] Based on the performance and advantages of the carbon quantum dots of the present invention, they can be applied to the detection and treatment technology of bisphenol A, and develop detection materials and adsorption materials such as electrodes, probes, sensors, and composite membranes.

[0017] In addition, the present invention also provides a bio-based composite film comprising the carbon quantum dots described above.

[0018] As a limitation of the above technical solution, the bio-based composite film also includes bio-based raw materials. Preferably, the bio-based raw materials include at least one of carboxymethyl cellulose, chitosan, and dealkalized lignin.

[0019] The method for preparing the bio-based composite film as described above comprises the following steps:

[0020] a. dissolving the bio-based raw material to obtain a bio-based raw material solution;

[0021] b. The bio-based raw material solution and the carbon quantum dot solution are uniformly mixed at 30-50° C. to obtain a casting solution; the mass ratio of the bio-based raw material solution and the carbon quantum dot solution is 10:1, the concentration of the bio-based raw material solution is 0.016 g / mL, and the concentration of the carbon quantum dot solution is adjusted to 0.1 g / mL with solvent water.

[0022] c. Drying the casting solution to obtain a CO2-responsive bio-based composite film material.

[0023] The CO2-responsive carbon quantum dots of the present invention are composited with a film substrate to effectively control the interaction between CO2 and the film. The size effect of the carbon quantum dots is utilized to improve their accessibility during the film pore structure adjustment process, allowing them to enter the film's interior, achieving a complete restructuring of the composite material from the inside out, resulting in an ideal composite film. The use of bio-based raw materials such as cellulose, lignin, and chitosan as the film substrate not only ensures adsorption performance, but also offers the advantages of a wide range of sources and environmental friendliness, making it suitable for large-scale production and application, and possessing broad application prospects.

[0024] Furthermore, the application of bio-based composite films can be used for the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater.

[0025] The bio-based composite film of the present invention exhibits a linear relationship between adsorption and fluorescence for different concentrations of bisphenol A in wastewater. The composite film can be used as an adsorption treatment material for bisphenol A in industrial wastewater, while achieving synchronous detection of the adsorption treatment process.

[0026] In summary, the carbon quantum dots of the present invention utilize the rich functional groups such as morpholine, amine, hydroxyl, carboxyl, and amide groups possessed by the precursor, combined with the post-modification of amino imidazole compounds, to have CO2 responsiveness, and at the same time have a linear fluorescence cluster quenching phenomenon for bisphenol A, and can also provide active sites to enhance the adsorption performance of the membrane, and can be used as a detection material and adsorption material for bisphenol A. The carbon quantum dots of the present invention are prepared into a bio-based composite film for the treatment of bisphenol A pollution in industrial wastewater, which can achieve efficient adsorption treatment and real-time reliable monitoring, solving the problem of low adsorption efficiency of bisphenol A in the current membrane separation, and making up for the steps of the bisphenol A detection process that require large instruments, cumbersome operations and difficult real-time monitoring. In addition, the composite film has the advantages of a wide source of raw materials, low cost, and green environmental protection, and has broad prospects in terms of economic, environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a transmission electron microscopy image of CO2-responsive carbon quantum dots prepared in Example 2 of the present invention;

[0028] Figure 2 This is the UV-visible absorption spectrum of the CO2-responsive carbon quantum dots prepared in Example 2 of the present invention;

[0029] Figure 3 The fluorescence emission spectrum and excitation spectrum of CO2-responsive carbon quantum dots prepared in Example 2 of the present invention;

[0030] Figure 4 This is a photo of the bio-based composite film prepared in Example 2 of the present invention, where (a) is under natural light conditions and (b) is under ultraviolet light conditions;

[0031] Figure 5 The contact angle changes of the bio-based composite film prepared in Example 2 of the present invention under different CO2 stimulations;

[0032] Figure 6 This is a fluorescence emission spectrum of the bio-based composite film prepared in Example 2 of the present invention added to bisphenol A wastewater with different concentrations;

[0033] Figure 7 This is a linear relationship diagram when the bio-based composite film prepared in Example 2 of the present invention is added to wastewater with different concentrations of bisphenol A. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The experimental methods in the following examples and comparative examples, unless otherwise specified, are conventional methods; the raw materials or test materials used, unless otherwise specified, are typical commercially available products. The quantitative tests in the following examples and comparative examples were all repeated three times, and the results were averaged.

[0036] This embodiment relates to the preparation of carbon quantum dots and bio-based composite films for simultaneous detection and adsorption treatment of bisphenol A, as well as application detection.

[0037] Example 1

[0038] CO2-responsive carbon quantum dots were prepared from morpholine and polyethylene glycol 400 in a molar ratio of 1:3 by the following steps:

[0039] S1. Mix 0.01 mol of morpholine and 0.03 mol of polyethylene glycol 400 evenly, then take 1 g of the mixture and add it to 30 mL of water. Heat it to 210°C in a hydrothermal reactor for 11 hours. After the reaction is completed, filter it to obtain a precursor solution.

[0040] S2. Take 5 g of the precursor solution obtained in step S1 and add it to a magnetic stirrer containing 10 g of 4-amino-5-imidazolecarboxamide. React under heating and stirring conditions at 60° C. for 1 h. After the reaction is completed, a carbon quantum dot A solution is obtained.

[0041] The above-mentioned carbon quantum dot solution and lignin (dealkalinization) are used to prepare a bio-based composite film of carbon quantum dot A and lignin (dealkalinization), and the specific preparation is as follows:

[0042] a. Take 0.8 g of raw material lignin (dealkalized) and dissolve it in 50 mL of dimethyl sulfoxide to obtain a lignin solution with a concentration of 0.016 g / mL;

[0043] b. Mix 10 g of lignin solution and 1 g of carbon quantum dot A solution adjusted to a concentration of 0.1 g / mL by adding solvent water, and stir at 30°C for 1 h until the mixture is uniform to obtain a casting solution;

[0044] c. Pour all the casting solution obtained in step b into a culture dish, put it into an oven and dry it at 40° C. for 4 hours to obtain a bio-based composite film material of carbon quantum dots A and lignin.

[0045] The carbon quantum dot A composite lignin film is applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater. The specific operation is as follows:

[0046] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5μg / L, 10μg / L, 30μg / L, 50μg / L, and 100μg / L, respectively. Then, 2cm-diameter circular carbon quantum dot A composite lignin films were immersed in 100mL of bisphenol A standard solutions of different concentrations. The color change of the films was observed under ultraviolet light. It was found that with the increase of bisphenol A solution concentration, the brightness of the films gradually decreased and the optical quenching phenomenon gradually increased. After soaking for half an hour, the films were taken out and dried in an oven at 40℃. The fluorescence intensity was measured using a fluorescence spectrophotometer. The standard curve of the relationship between bisphenol A concentration and fluorescence intensity was linear, with a detection range of 5-100μg / L and a detection limit of 2.92μg / L, which proved that the composite film had good detection performance for bisphenol A.

[0047] (2) Take 2g of carbon quantum dot A composite lignin film and add it to 20g of bisphenol A wastewater sample of unknown concentration to be tested, and perform adsorption treatment in a constant temperature water bath oscillator at 50℃. Make a qualitative judgment based on the adsorption of pollutants combined with the directly observed color change of the mixed solution under ultraviolet light. When the color no longer changes and stabilizes for 2 minutes, the adsorption reaches equilibrium and the experiment ends.

[0048] After the film was removed from the wastewater sample and dried, the concentration of bisphenol A on the film was measured by fluorescence spectrophotometry. The adsorption rate of bisphenol A in the wastewater by the film was quantitatively calculated to be 88.2%.

[0049] Example 2

[0050] CO2-responsive carbon quantum dots were prepared from 4-acetylmorpholine and polyethylene glycol 400 in a molar ratio of 1:2 by the following steps:

[0051] S1. Mix 0.01 mol of 4-acetylmorpholine and 0.02 mol of polyethylene glycol 400 evenly, then take 1 g of the mixture and add it to 40 mL of water. Heat it to 200° C. in a hydrothermal reactor and react for 12 h. After the reaction is completed, filter it to obtain a precursor solution.

[0052] S2. Take 5 g of the precursor solution obtained in step S1 and add it to a magnetic stirrer containing 12 g of 1-(1H-imidazole-1-carboximido)-1H-imidazole. React under heating and stirring conditions at 50° C. for 1.5 h to obtain a carbon quantum dot B solution.

[0053] Figure 1 This is a transmission electron microscope image of the carbon quantum dots prepared in this example. It can be seen that the prepared carbon quantum dots are uniformly spherical and have a relatively uniform particle size distribution, mainly ranging from 2 to 9 nm.

[0054] Figure 2 The photoluminescence properties of the material were determined using an ultraviolet-visible absorption spectrometer and a fluorescence spectrophotometer. The analysis found that the carbon quantum dots have obvious ultraviolet absorption peaks and fluorescence characteristic peaks in the ultraviolet region, with the absorption peaks concentrated at 232nm and 295nm, respectively. The characteristic absorption peak at 232nm is attributed to the n→σ* transition of the amino group, and the characteristic absorption peak at 295nm may be caused by the π-π* transition on the aromatic ring.

[0055] Figure 3 This is the fluorescence spectrum of the material. Under the excitation wavelength of 330nm, carbon quantum dots can emit bright blue fluorescence, and the corresponding optimal emission wavelength is 394nm.

[0056] The carbon quantum dot solution and carboxymethyl cellulose were used to prepare a bio-based composite film of carbon quantum dot B and carboxymethyl cellulose, and the specific preparation method was as follows:

[0057] a. Take 0.8 g of carboxymethyl cellulose and dissolve it in 50 mL of deionized water to obtain a carboxymethyl cellulose solution with a concentration of 0.016 g / mL;

[0058] b. Mix 10 g of carboxymethyl cellulose solution and 1 g of carbon quantum dot B solution adjusted to a concentration of 0.1 g / mL by adding solvent water, and stir at 50° C. for 1 h until the mixture is uniform to obtain a casting solution;

[0059] c. Pour all the casting solution obtained in step b into a culture dish, put it into an oven and dry it at 40° C. for 4 hours to obtain a biomass composite film material of carbon quantum dots B and carboxymethyl cellulose.

[0060] Figure 4These are actual photos of carbon quantum dot B composite carboxymethyl cellulose film under natural light and ultraviolet light conditions. It can be seen that the film has good transparency and is colorless under natural light, but exhibits a distinct bright blue color under ultraviolet light, with obvious photoluminescence properties, which provides feasibility for subsequent pollutant detection.

[0061] Figure 5 The figure shows the change in the contact angle of the composite film as the CO2 flow rate increases from low to high. As can be seen from the figure, the contact angle of the film gradually increases with increasing CO2 flow rate, and the hydrophobicity of the film gradually increases, achieving the goal of dynamically adjusting the hydrophilic and hydrophobic properties of the film using CO2. Furthermore, the pure water flux and porosity of the composite film at different CO2 gas flow rates were measured using a vacuum pump and filtration device using the mass method. The experimental results are shown in Table 1.

[0062] Table 1 Water flux and porosity of composite films at different CO2 gas flow rates

[0063] sample <![CDATA[CO2 flow rate (mL·min -1 )]]> Porosity (%) <![CDATA[Water flux (L m -2 h -1 )]]> (ⅰ) 100 81.7 53.1 (ⅱ) 200 89.5 580.6 (ⅲ) 300 92.4 670.9

[0064] It can be seen from the results in the above table that the composite film exhibits significantly different pure water fluxes under different gas flow rates, which shows that the film does have corresponding dynamic responsiveness under CO2 stimulation. This may be because the abundant hydroxyl groups at the chain ends of the cellulose composite film are protonated under CO2 stimulation, and the film is transformed from the original pore-tightened and closed state to an extended state with a large number of microporous structures, thereby increasing the pure water flux.

[0065] The carbon quantum dot B composite carboxymethyl cellulose film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater. The specific operation is as follows:

[0066] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5μg / L, 10μg / L, 30μg / L, 50μg / L, and 100μg / L respectively; then, immerse a circular carbon quantum dot B composite carboxymethyl cellulose film with a diameter of 2cm in 100mL of bisphenol A standard solutions with different concentrations, and observe the color change of the film under ultraviolet light. It was found that with the increase of the concentration of bisphenol A solution, the brightness of the film gradually decreased, and the optical quenching phenomenon gradually increased. After soaking for half an hour, take out the film and dry it in an oven at 40℃. The fluorescence intensity was measured using a fluorescence spectrophotometer. When the bisphenol A detection range was 5-100μg / L, the change in bisphenol A concentration and the ultraviolet fluorescence intensity of the film was as follows: Figure 6 As shown, the relationship between bisphenol A concentration and fluorescence intensity was fitted, and the results showed a good linear relationship. Figure 7 The detection limit was 0.70 μg / L, which proved that the composite film had good detection performance for bisphenol A.

[0067] (2) Take 2g of carbon quantum dot B composite carboxymethyl cellulose film and add it to 20g of bisphenol A wastewater sample of unknown concentration to be tested, and perform adsorption treatment in a constant temperature water bath oscillator at 50℃. Make a qualitative judgment based on the adsorption of pollutants combined with the directly observed color change of the mixed solution under ultraviolet light. When the color no longer changes and stabilizes for 2 minutes, the adsorption reaches equilibrium and the experiment ends.

[0068] After the film was taken out from the wastewater sample and dried, the concentration of bisphenol A in the film was determined by fluorescence spectrophotometry. The adsorption rate of bisphenol A in the wastewater by the film was quantitatively calculated to be 98.4%.

[0069] Example 3

[0070] CO2-responsive carbon quantum dots were prepared from morpholin-4-acetic acid and polyethylene glycol 200 in a molar ratio of 1:1 by the following steps:

[0071] S1. Mix 0.02 mol of morpholin-4-acetic acid and 0.02 mol of polyethylene glycol 200 evenly, then take 1 g of the mixture and add it to 30 mL of water. Heat it to 220° C. in a hydrothermal reactor for 14 h. After the reaction is completed, filter it to obtain a precursor solution.

[0072] S2. Take 5 g of the precursor solution obtained in step S1, add it into a magnetic stirrer containing 1.5 g of 4-amino-5-imidazolecarboxamide, and react under heating and stirring conditions at 80° C. for 2 h to obtain a carbon quantum dot C solution.

[0073] The carbon quantum dot solution and lignin (dealkalinization) are used to prepare a bio-based composite film of carbon quantum dot C and lignin (dealkalinization), and the specific preparation is as follows:

[0074] a. Take 0.8 g of raw material lignin (dealkalized) and dissolve it in 50 mL of dimethyl sulfoxide to obtain a lignin solution with a concentration of 0.016 g / mL;

[0075] b. Mix 10 g of lignin solution and 1 g of carbon quantum dot C solution adjusted to a concentration of 0.1 g / mL by adding solvent water, and stir at 30 ° C for 1 h until the mixture is uniform to obtain a casting solution;

[0076] c. Pour all the casting solution obtained in step b into a culture dish, put it into an oven and dry it at 40° C. for 4 hours to obtain a bio-based composite film material of carbon quantum dots C and lignin.

[0077] The carbon quantum dot C composite lignin film is applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater. The specific operation is as follows:

[0078] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5μg / L, 10μg / L, 30μg / L, 50μg / L, and 100μg / L, respectively. Then, immerse a 2cm diameter circular carbon quantum dot C composite lignin film in 100mL of bisphenol A standard solutions of different concentrations. Observe the color change of the film under ultraviolet light. It is found that with the increase of bisphenol A solution concentration, the brightness of the film gradually decreases and the optical quenching phenomenon gradually increases. After soaking for half an hour, take out the film and dry it in an oven at 40℃. Use a fluorescence spectrophotometer to measure the fluorescence intensity. The established standard curve of the relationship between bisphenol A concentration and fluorescence intensity is linear. The detection range is 5-100μg / L, and the detection limit is 0.91μg / L, which proves that the composite film has good detection performance for bisphenol A.

[0079] (2) Take 2g of carbon quantum dot C composite lignin film and add it to 20g of bisphenol A wastewater sample of unknown concentration to be tested, and perform adsorption treatment in a constant temperature water bath oscillator at 50℃. Make a qualitative judgment based on the adsorption of pollutants combined with the directly observed color change of the mixed solution under ultraviolet light. When the color no longer changes and stabilizes for 2 minutes, the adsorption reaches equilibrium and the experiment ends.

[0080] After the film was taken out from the wastewater sample and dried, the concentration of bisphenol A on the film was measured by fluorescence spectrophotometry. The quantitative calculation showed that the adsorption rate of bisphenol A in the wastewater by the film was 93.8%.

[0081] Example 4

[0082] CO2-responsive carbon quantum dots were prepared from 4-aminomorpholine and polyethylene glycol 400 in a molar ratio of 3:1 by the following steps:

[0083] S1. Mix 0.03 mol of 4-aminomorpholine and 0.01 mol of polyethylene glycol 400 evenly. Then, take 1 g of the mixture and add it to 40 mL of water. Heat it to 180° C. in a hydrothermal reactor for 12 h. After the reaction is completed, filter it to obtain a precursor solution.

[0084] S2. Take 5 g of the precursor solution obtained in step S1 and add it to a magnetic stirrer containing 8 g of 1-(1H-imidazole-1-carboximido)-1H-imidazole. React under heating and stirring conditions at 80° C. for 0.5 h to obtain a carbon quantum dot D solution.

[0085] The carbon quantum dot solution and carboxymethyl cellulose were used to prepare a bio-based composite film of carbon quantum dots D and carboxymethyl cellulose, and the specific preparation method was as follows:

[0086] a. Take 0.8 g of carboxymethyl cellulose and dissolve it in 50 mL of deionized water to obtain a carboxymethyl cellulose solution with a concentration of 0.016 g / mL;

[0087] b. Mix 10 g of carboxymethyl cellulose solution and 1 g of carbon quantum dot D solution adjusted to a concentration of 0.1 g / mL by adding solvent water, and stir at 30° C. for 1 h until the mixture is uniform to obtain a casting solution;

[0088] c. Pour all the casting solution obtained in step b into a culture dish, put it into an oven and dry it at 40° C. for 4 hours to obtain a bio-based composite film material of carbon quantum dots D and carboxymethyl cellulose.

[0089] The carbon quantum dot D composite carboxymethyl cellulose film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater. The specific operation is as follows:

[0090] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5μg / L, 10μg / L, 30μg / L, 50μg / L, and 100μg / L, respectively. Then, immerse a 2cm diameter circular carbon quantum dot D composite carboxymethyl cellulose film in 100mL of bisphenol A standard solutions of different concentrations. Observe the color change of the film under ultraviolet light. It is found that with the increase of bisphenol A solution concentration, the brightness of the film gradually decreases and the optical quenching phenomenon gradually increases. After soaking for half an hour, take out the film and dry it in an oven at 40℃. Use a fluorescence spectrophotometer to measure the fluorescence intensity. The established standard curve of the relationship between bisphenol A concentration and fluorescence intensity is linear. The detection range is 5-100μg / L, and the detection limit is 5.66μg / L, which proves that the composite film has good detection performance for bisphenol A.

[0091] (2) Take 2g of carbon quantum dot D composite carboxymethyl cellulose film and add it to 20g of bisphenol A wastewater sample of unknown concentration to be tested, and perform adsorption treatment in a constant temperature water bath oscillator at 50℃. Make a qualitative judgment based on the adsorption of pollutants combined with the directly observed color change of the mixed solution under ultraviolet light. When the color no longer changes and stabilizes for 2 minutes, the adsorption reaches equilibrium and the experiment ends.

[0092] After the film was taken out from the wastewater sample and dried, the concentration of bisphenol A in the film was determined by fluorescence spectrophotometry. The adsorption rate of bisphenol A in the wastewater by the film was quantitatively calculated to be 90.13%.

[0093] Example 5

[0094] CO2-responsive carbon quantum dots were prepared from 4-acetylmorpholine and polyethylene glycol 200 in a molar ratio of 2:1 by the following steps:

[0095] S1. Mix 0.02 mol of 4-acetylmorpholine and 0.01 mol of polyethylene glycol 200 evenly, then take 1 g of the mixture and add it to 20 mL of water. Heat it to 200° C. in a hydrothermal reactor and react for 14 h. After the reaction is completed, filter it to obtain a precursor solution.

[0096] S2. Take 5 g of the precursor solution obtained in step S1, add it into a magnetic stirrer containing 6.5 g of 5-azabenzimidazole, and react under heating and stirring conditions at 40° C. for 2 h to obtain a carbon quantum dot E solution.

[0097] The carbon quantum dot solution and chitosan were used to prepare a bio-based composite film of carbon quantum dot E and chitosan, and the specific preparation method was as follows:

[0098] a. Take 0.8 g of raw chitosan and dissolve it in 50 mL of N,N-dimethylformamide to obtain a chitosan solution with a concentration of 0.016 g / mL;

[0099] b. Mix 10 g of chitosan solution and 1 g of carbon quantum dot E solution adjusted to a concentration of 0.1 g / mL by adding solvent water, and stir at 30° C. for 1 h until the mixture is uniform to obtain a casting solution;

[0100] c. Pour all the casting solution obtained in step b into a culture dish, put it into an oven and dry it at 40° C. for 4 hours to obtain a bio-based composite film material of carbon quantum dots E and chitosan.

[0101] The carbon quantum dot E composite chitosan film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater. The specific operation is as follows:

[0102] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5μg / L, 10μg / L, 30μg / L, 50μg / L, and 100μg / L, respectively. Then, immerse a 2cm diameter circular carbon quantum dot E composite chitosan film in 100mL of bisphenol A standard solutions of different concentrations. Observe the color change of the film under ultraviolet light. It is found that with the increase of bisphenol A solution concentration, the brightness of the film gradually decreases and the optical quenching phenomenon gradually increases. After soaking for half an hour, take out the film and dry it in an oven at 40℃. Use a fluorescence spectrophotometer to measure the fluorescence intensity. The established standard curve of the relationship between bisphenol A concentration and fluorescence intensity is linear. The detection range is 5-100μg / L, and the detection limit is 2.5μg / L. This proves that the composite film has good detection performance for bisphenol A.

[0103] (2) Take 2g of carbon quantum dot E composite chitosan film and add it to 20g of bisphenol A wastewater sample of unknown concentration to be tested, and perform adsorption treatment in a constant temperature water bath oscillator at 50℃. Make a qualitative judgment based on the adsorption of pollutants combined with the directly observed color change of the mixed solution under ultraviolet light. When the color no longer changes and stabilizes for 2 minutes, the adsorption reaches equilibrium and the experiment ends.

[0104] After the film was taken out from the wastewater sample and dried, the concentration of bisphenol A in the film was determined by fluorescence spectrophotometry. The adsorption rate of bisphenol A in the wastewater by the film was quantitatively calculated to be 82.7%.

[0105] Comparative Example 1

[0106] The preparation method of the CO2-responsive carbon quantum dot composite bio-based film provided in this comparative example is different from that of Example 2 only in that 4-acetylmorpholine in Example 2 is replaced by an equal amount of N-methylmorpholine. The rest is exactly the same, and the specific operations are not repeated here.

[0107] The composite film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater in exactly the same manner as in Example 2. The results showed that the detection range of the film was 5-100 μg / L, the detection limit was 28.35 μg / L, and the adsorption rate of bisphenol A was 83.8%.

[0108] The composite film of this comparative example has a relatively general detection performance for bisphenol A, which is significantly inferior to that of Example 2. This may be because the raw material 4-acetylmorpholine in Example 2 has abundant amide groups. As a typical hydrogen bond acceptor structure, the unpaired electrons of the C=O bond on the amide can provide electrons, and then can effectively accept the hydrogen provided by the hydroxyl group in the bisphenol A structure as a hydrogen bond donor. Under this hydrogen bond effect, Example 2 using 4-acetylmorpholine as raw material can efficiently and accurately identify bisphenol A in wastewater. However, the raw material N-methylmorpholine selected in this comparative example has a primary amine replaced by a methyl group without a hydrogen bond acceptor, and the structure has a certain steric effect due to the entry of the methyl group, which greatly weakens the number and performance of the original hydrogen bond acceptors in the morpholine structure. As a result, the possibility of the carbon quantum dots prepared in this comparative example interacting with bisphenol A is significantly reduced, causing a decline in detection performance. At the same time, adsorption performance is also reduced, which may also be caused by the reduction of amine active functional groups.

[0109] Comparative Example 2

[0110] The preparation method of the CO2-responsive carbon quantum dot composite bio-based film provided in this comparative example is different from that of Example 2 only in that the 1-(1H-imidazole-1-carboxylic imide)-1H-imidazole in Example 2 is replaced by an equal amount of benzimidazole, and the rest are exactly the same, and the specific operations are not repeated here.

[0111] The composite film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater using a method identical to that of Example 2. The results showed that the film had a detection range of 5 to 100 μg / L and a detection limit of 6.99 μg / L, indicating that the composite film had good detection performance for bisphenol A. However, the adsorption rate of bisphenol A decreased significantly, reaching only 60.7%. This is likely due to the significant structural differences between the raw material benzimidazole in this comparative example and the 1-(1H-imidazole-1-carboxylic imide)-1H-imidazole used in the original Example 2. The differences in the interaction of these functional groups with CO2 led to the difference in bisphenol A adsorption performance. First, the imidazole group plays a role in the CO2 response during material preparation. The presence of two imidazole groups in Example 2 increases the probability of the precursor interacting with CO2 and the amount of CO2 introduced, thereby better participating in adjusting the film structure during subsequent composite film preparation, resulting in a film with excellent performance. Furthermore, the 1-(1H-imidazole-1-carboximido)-1H-imidazole in Example 2 also has a highly reactive amine group, which can further increase the number of active adsorption sites in the composite film. In contrast, the benzimidazole in this comparative example not only lacks the CO2 functional group that can adjust the film, but also has an introduced phenyl group that cannot serve as an adsorption site and has a certain degree of biological toxicity, potentially causing environmental pollution.

[0112] Comparative Example 3

[0113] The preparation method of the CO2-responsive carbon quantum dot composite bio-based film provided in this comparative example is different from that of Example 2 only in that the carboxymethyl cellulose film in Example 2 is replaced by an equal amount of polyethylene film. The rest is exactly the same, and the specific operations are not repeated here.

[0114] The composite film was applied to the simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater in exactly the same manner as in Example 2. The results showed that the detection range of the film was 5 to 100 μg / L, the detection limit was 15.6 μg / L, and the detection performance of the composite film for bisphenol A was reduced. The adsorption rate of bisphenol A was significantly reduced to only 38.6%. This shows that the compatibility of the film and CO2-responsive carbon quantum dots will directly affect the adsorption treatment performance. In addition, from an environmental perspective, the selected bio-based raw materials are greener, low-cost, and widely available, which is more in line with the requirement of treating waste with waste.

[0115] In summary, the carbon quantum dots of the present invention have CO2 responsiveness, exhibit linear fluorescence clustering quenching for bisphenol A, and provide active sites to enhance membrane adsorption performance, making them useful as detection and adsorption materials for bisphenol A. The bio-based composite film prepared from the carbon quantum dots of the present invention can achieve efficient adsorption treatment and real-time, reliable monitoring in the treatment of bisphenol A contamination in industrial wastewater. This not only addresses the low adsorption efficiency problem currently associated with membrane separation of bisphenol A, but also overcomes the bisphenol A detection process, which requires large instruments, is cumbersome to operate, and is difficult to monitor in real time. Furthermore, the composite film has the advantages of a wide source of raw materials, low cost, and environmental friendliness, offering broad prospects for economic, environmental, and social benefits.

[0116] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of this application, several variations and improvements can be made, which all fall within the scope of protection of this application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A carbon quantum dot for simultaneous detection and adsorption treatment of bisphenol A, characterized by: The carbon quantum dots are prepared by reacting morpholine and / or morpholine derivatives with polyethylene glycol through a solvent thermal reaction to obtain a precursor solution, which is then heated with an aminoimidazole compound to react; The morpholine and / or morpholine derivatives include at least one of morpholine, 4-acetylmorpholine, 4-aminomorpholine, and morpholin-4-yl acetic acid.

2. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized in that: The polyethylene glycol includes at least one of polyethylene glycol 200 and polyethylene glycol 400; and / or the aminoimidazole compound includes at least one of 2-aminoimidazole, 4-amino-5-imidazolecarboxamide, 5-azabenzimidazole, and 1-(1H-imidazole-1-carboxylimide)-1H-imidazole.

3. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized in that: The molar ratio of morpholine and / or morpholine derivatives to polyethylene glycol is 3:1-9; and / or the temperature of the solvent thermal reaction is 180-220° C. and the time is 8-12 hours.

4. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized in that: In the precursor solution, the ratio of the total mass of the solute morpholine, morpholine derivatives and polyethylene glycol to the solvent water is 1g:20~40mL; and / or, the mass ratio of the precursor solution to the aminoimidazole compound is 4:1~10, and / or, the heating reaction temperature is 40~80℃ and the time is 0.5~2h.

5. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to any one of claims 1 to 4, characterized in that: The carbon quantum dots are CO2 responsive carbon quantum dots.

6. The use of carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to any one of claims 1 to 5, characterized in that: As an effective substance for detecting and / or adsorbing bisphenol A, it is used to prepare detection materials and adsorption materials for bisphenol A.

7. A bio-based composite film, characterized in that: Comprising the carbon quantum dots according to any one of claims 1 to 5.

8. The bio-based composite film according to claim 7, characterized in that: It also includes bio-based raw materials. Preferably, the bio-based raw materials include at least one of carboxymethyl cellulose, chitosan, and dealkalized lignin.

9. The method for preparing a bio-based composite film according to claim 8, wherein: The method comprises the following preparation steps: a. dissolving the bio-based raw material to obtain a bio-based raw material solution; b. mixing the bio-based raw material solution and the carbon quantum dot solution at 30-50° C. to obtain a casting solution; c. drying the casting solution to obtain a CO2-responsive bio-based composite film material; Preferably, the mass ratio of the bio-based raw material solution and the carbon quantum dot solution is 10:1, the concentration of the bio-based raw material solution is 0.016 g / mL, and the concentration of the carbon quantum dot solution is adjusted to 0.1 g / mL by solvent water.

10. The use of the bio-based composite film according to claim 7 or 8, characterized in that: Used for simultaneous detection and adsorption treatment of the pollutant bisphenol A in industrial wastewater.

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