Carbon quantum dots, bio-based composite membrane for simultaneous detection and adsorption treatment of bisphenol a and preparation and application thereof

Abstract

The application discloses a kind of carbon quantum dots for synchronous detection and adsorption treatment bisphenol A, precursor solution is obtained by solvothermal reaction from morpholine and / or morpholine derivative and polyethylene glycol, then heated with amido imidazole compound to prepare;The morpholine and / or morpholine derivative include at least one of morpholine, 4-acetyl morpholine, 4-amino morpholine, morpholine-4-yl acetic acid.The carbon quantum dots of the application have CO2 response function, linear fluorescence cluster extinction phenomenon to bisphenol A at the same time, can also provide active site to enhance membrane adsorption performance, can be used as the detection material and adsorption material of bisphenol A.Biobased composite film prepared from the carbon quantum dots of the application can realize efficient adsorption treatment and real-time reliable monitoring in the application of bisphenol A pollution treatment of industrial wastewater, also has the advantages of wide raw material source, low cost, green and environmental protection, has broad prospects in economic, environmental and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon quantum dots, in particular to a CO2-responsive carbon quantum dot capable of detecting bisphenol A and also capable of being used on a bisphenol A adsorption treatment material, a bio-based composite film containing the CO2-responsive carbon quantum dot, and application of the same in detection and treatment of bisphenol A pollutants. BACKGROUND

[0002] Bisphenol A (BPA) is a key raw material for producing polycarbonate plastics, epoxy resins and other polymer materials. It is indispensable in many daily and industrial products such as food and beverage packaging, baby bottles, sports water bottles, glasses, medical devices, etc. With the increasing production of bisphenol A in recent years, the pollution hazards caused by it are also becoming more and more serious.

[0003] From the environmental point of view, bisphenol A is difficult to degrade in the natural environment and can exist in the soil, water and other media for a long time, causing damage to the ecological system. Specifically, low concentrations of bisphenol A can interfere with the endocrine system of aquatic organisms, affecting the growth, development and reproduction of fish, shellfish and other organisms, leading to a decline in population size. In the body, bisphenol A has biological accumulation and can be enriched along the food chain. In terms of human health, bisphenol A is similar in structure to female hormones in the human endocrine system and is an endocrine disruptor, affecting the development and function of the reproductive, nervous and immune systems. Therefore, the detection and treatment of bisphenol A are the key to solving bisphenol A pollution.

[0004] Currently, the detection techniques for bisphenol A mainly include atomic absorption method, high performance liquid chromatography, gas chromatography-mass spectrometry and chemical titration. These detection techniques generally have problems such as the need for expensive large instruments, complex detection steps, high requirements for the professional level of operators, and difficulty in 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. Carbon quantum dots have shown advantages in the field of analysis and detection due to their good biocompatibility, high fluorescence stability and easy surface functionalization, for example, some studies have used carbon quantum dots to modify glassy carbon electrodes, which have shown significant enrichment and detection performance for the analyte. Although the research on carbon quantum dot related technologies in the detection field is continuously deepening, the detection of bisphenol A still faces challenges such as cost control, application portability and stability optimization, and further exploration and breakthroughs are needed. SUMMARY

[0006] The present application aims at the problems of bisphenol A detection being complicated and difficult to be monitored in real time, and develops a carbon quantum dot with CO2 response characteristics, which can realize synchronous detection and adsorption treatment of bisphenol A.

[0007] To achieve the above-mentioned purpose, the carbon quantum dot for synchronous detection and adsorption treatment of bisphenol A is prepared by heating reaction of a precursor solution obtained by solvothermal reaction of morpholine and / or morpholine derivatives and polyethylene glycol with an amine-based imidazole compound.

[0008] The morpholine and / or morpholine derivatives include at least one of morpholine, 4-acetyl morpholine, 4-amino morpholine and morpholine-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 amine-based imidazole compound includes at least one of 2-aminoimidazole, 4-amino-5-imidazole formamide, 5-azabenzimidazole and 1-(1H-imidazole-1-carboxamidyl)-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 solvothermal reaction is 180-220 DEG C, and the time is 8-12 h.

[0011] As a limitation of the above technical solution, in the precursor solution, the mass ratio of the solutes 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 amine-based imidazole compound is 4:1-10, the temperature of the heating reaction is 40-80 DEG C, and the time is 0.5-2 h.

[0012] As a limitation of the above technical solution, the carbon quantum dot is a CO2 response type carbon quantum dot.

[0013] The carbon quantum dot is obtained in two steps, the first step is to form a precursor by hydrogen bonding between morpholine, morpholine derivatives and polyethylene glycol under the action of hydrothermal, and the second step is to perform post-modification of the precursor with an amine-based imidazole compound to generate a carbon quantum dot material with CO2 response characteristics.

[0014] The carbon quantum dots have the following advantages: first, the precursor has rich functional groups such as morpholine, amine group, hydroxyl group, carboxyl group and amide group, which are used as active sites of the composite material to improve the adsorption performance. Second, the amine group imidazole compound is selected as the raw material, the imidazole group which can be used under the stimulation of CO2 is retained, and the amine group which can enhance the CO2 response is introduced, so that only the input and output of CO2 gas are involved in the dynamic regulation of the material pore process, no secondary pollution is generated, and the energy consumption is low. Third, in the material preparation process, the post-modification method is used, that is, the precursor is prepared first, and then the CO2 responsive functional groups are connected to the precursor through the modification method, so that the CO2 responsive functional groups do not undergo the high temperature and high pressure process of the solvent thermal reaction, and the characteristics of the functional groups are retained as much as possible. Fourth, the photoluminescence characteristics of the carbon quantum dots are used to realize the synchronous monitoring in the pollutant treatment process, and the reaction process is realized in real time.

[0015] Meanwhile, the application also provides the application of the carbon quantum dots for synchronous detection and adsorption treatment of bisphenol A, that is, as an effective substance for detecting and / or adsorbing bisphenol A, for preparing a detection material and an adsorption material of bisphenol A.

[0016] Based on the performance and advantages of the carbon quantum dots, the carbon quantum dots can be applied to the detection and treatment technology of bisphenol A, and the detection material and the adsorption material such as an electrode, a probe, a sensor and a composite film are developed.

[0017] In addition, the application also provides a bio-based composite film containing the carbon quantum dots.

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

[0019] The preparation method of the bio-based composite film is as follows:

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

[0021] b. mixing the bio-based raw material solution and the carbon quantum dot solution uniformly at 30-50 DEG 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 by 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 application are compounded with a film substrate, the interaction of CO2 and the film body is effectively controlled, the size effect of the carbon quantum dots is utilized, the contactability of the carbon quantum dots and the film in the process of adjusting the pore structure of the film is improved, the carbon quantum dots enter the internal space of the film, the composite material is reformed from inside to outside, and an ideal composite film is obtained. The biological base materials such as cellulose, lignin and chitosan are selected as the film substrate, on the basis of ensuring the adsorption performance, the biological base materials also have the advantages of wide source and green environmental protection, are suitable for large-scale production and application, and have wide application prospect.

[0024] Further, the biological base composite film can be used for synchronous detection and adsorption treatment of pollutants bisphenol A in industrial wastewater.

[0025] Based on the biological base composite film of the application, the adsorption effect and the fluorescence linear relationship of the composite film to bisphenol A in wastewater of different concentrations are exhibited, the composite film can be used as an adsorption treatment material for bisphenol A in industrial wastewater, and synchronous detection in the adsorption treatment process is realized.

[0026] In summary, the carbon quantum dots of the application utilize the rich functional groups such as morpholine, amine group, hydroxyl group, carboxyl group and amide group of the precursor, and the post-modification of the amine group imidazole compound, have the CO2-responsive function, have the linear fluorescence cluster extinction phenomenon to bisphenol A, can provide active sites to enhance the adsorption performance of the film, and can be used as a detection material and an adsorption material for bisphenol A. The carbon quantum dots of the application are prepared into a biological base composite film, and are used for bisphenol A pollution treatment of industrial wastewater, can realize efficient adsorption treatment and real-time reliable monitoring, solve the problem of low adsorption efficiency of bisphenol A in the current membrane separation, make up the steps that large instruments are needed in the detection process of bisphenol A, the operation is complicated, and real-time monitoring is difficult, and the composite film also has the advantages of wide raw material source, low cost and green environmental protection, and has wide prospect in economic, environmental and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The transmission electron microscope image of the CO2-responsive carbon quantum dots prepared in Example 2 of the application;

[0028] Figure 2 The ultraviolet-visible absorption spectrum of the CO2-responsive carbon quantum dots prepared in Example 2 of the application;

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

[0030] Figure 4 The actual object diagram of the biological base composite film prepared in Example 2 of the application, wherein (a) is under natural light conditions, and (b) is under ultraviolet light conditions;

[0031] Figure 5 Contact angle change of the bio-based composite film prepared for the present embodiment 2 under different CO2 stimuli;

[0032] Figure 6 Fluorescence emission spectrum of the bio-based composite film prepared for the present embodiment 2 added to bisphenol A wastewater of different concentrations;

[0033] Figure 7 Linear relationship diagram of the bio-based composite film prepared for the present embodiment 2 added to bisphenol A wastewater of different concentrations. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described below in conjunction with embodiments, and obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] The experimental methods in the following examples and comparative examples are all conventional methods, unless otherwise specified; the raw materials or test materials used are all typical products purchased on the market, unless otherwise specified. In the quantitative tests in the following examples and comparative examples, three repeated experiments are set up, and the average value is taken as the result.

[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 their application in detection.

[0037] Example 1

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

[0039] S1, 0.01 mol of morpholine and 0.03 mol of polyethylene glycol 400 were mixed uniformly, then 1 g of the mixture was added to 30 mL of water, and heated to 210℃ in a hydrothermal reactor for 11 h. After the reaction was completed, the precursor solution was obtained by filtration.

[0040] S2, 5 g of the precursor solution obtained in step S1 was added to a magnetic stirrer containing 10 g of 4-amino-5-imidazole formamide, and reacted under the conditions of heating and stirring at 60℃ for 1 h. After the reaction was completed, carbon quantum dots A solution was obtained.

[0041] The bio-based composite film of carbon quantum dots A composite lignin (dealkalized) was prepared using the above carbon quantum dots solution and lignin (dealkalized), according to the following specific preparation:

[0042] a. 0.8 g of raw lignin (dealkalized) was dissolved in 50 mL of dimethyl sulfoxide to obtain a lignin solution with a concentration of 0.016 g / mL;

[0043] b. 10 g of the lignin solution and 1 g of carbon quantum dot A solution with a concentration of 0.1 g / mL were mixed in a solvent of water, and the mixture was stirred at a temperature of 30°C for 1 h until it was uniformly mixed to obtain a casting solution;

[0044] c. The entire casting solution obtained in step b was poured into a culture dish and placed in an oven for drying at 40°C for 4 h to obtain a bio-based composite thin film material of carbon quantum dot A composite lignin.

[0045] The carbon quantum dot A composite lignin thin film was applied to the simultaneous detection of industrial wastewater and the adsorption treatment of pollutants bisphenol A, and the specific operation was as follows:

[0046] (1) A standard curve was established. First, bisphenol A standard solutions with concentrations of 5 μg / L, 10 μg / L, 30 μg / L, 50 μg / L, and 100 μg / L were prepared; then a circular carbon quantum dot A composite lignin thin film with a diameter of 2 cm was immersed in 100 mL of bisphenol A standard solution with different concentrations, and the color change of the thin film was observed under ultraviolet light. It was found that the brightness of the thin film gradually decreased and the optical quenching phenomenon gradually increased with the increase of the concentration of bisphenol A solution. The thin film was taken out after half an hour of immersion and dried in an oven at 40°C. The fluorescence intensity was determined by a fluorescence spectrophotometer, and the standard curve of the relationship between the concentration of bisphenol A and the fluorescence intensity showed a linear relationship. The detection range was 5-100 μg / L, and the detection limit was 2.92 μg / L, proving that the composite thin film had good detection performance for bisphenol A.

[0047] (2) 2 g of carbon quantum dot A composite lignin thin film was added to 20 g of unknown concentration bisphenol A wastewater sample, and adsorption treatment was carried out in a 50°C constant temperature water bath shaker. Qualitative determination was made by combining the adsorption of pollutants with the color change of the mixed solution observed directly under ultraviolet light. When the color no longer changed and stabilized for 2 min, the adsorption reached equilibrium, and the experiment ended.

[0048] After the thin film was taken out from the wastewater sample and dried, the concentration of bisphenol A on the thin film was determined by fluorescence spectrophotometry, and the adsorption rate of the thin film for bisphenol A in wastewater was quantitatively calculated as 88.2%.

[0049] Example 2

[0050] Carbon quantum dots responsive to CO2 were prepared from 4-acetyl morpholine and polyethylene glycol 400 at a molar ratio of 1:2 according to the following steps:

[0051] S1, 0.01 mol 4-acetyl morpholine and 0.02 mol polyethylene glycol 400 were mixed uniformly, then 1 g of the mixture was added to 40 mL water, heated to 200°C in a hydrothermal reactor for 12 h, and then filtered to obtain a precursor solution.

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

[0053] Figure 1 The transmission electron microscope image of the carbon quantum dots prepared in this example showed that the prepared carbon quantum dots were uniform spherical particles with a relatively uniform particle size distribution, mainly in the range of 2-9 nm.

[0054] Figure 2 The photoluminescence properties of the material were determined by UV-visible absorption spectrometer and fluorescence spectrophotometer. It was found that the carbon quantum dots had obvious UV absorption peaks and fluorescence characteristic peaks in the UV region, and the absorption peaks were concentrated at 232 nm and 295 nm. The characteristic absorption peak at 232 nm was attributed to the n→σ* transition of the amine group, and the characteristic absorption peak at 295 nm was possibly caused by the π-π* transition of the aromatic ring.

[0055] Figure 3 The fluorescence spectrum of the material showed that the carbon quantum dots could emit bright blue fluorescence under the condition of an excitation wavelength of 330 nm, and the optimal emission wavelength was 394 nm.

[0056] A bio-based composite film of carbon quantum dot B composite carboxymethyl cellulose was prepared using the above carbon quantum dot solution and carboxymethyl fiber, and the preparation was as follows:

[0057] a, 0.8 g of raw material carboxymethyl cellulose was dissolved in 50 mL of deionized water to obtain a carboxymethyl cellulose solution with a concentration of 0.016 g / mL;

[0058] b, 10 g of carboxymethyl cellulose solution and 1 g of carbon quantum dot B solution with a concentration of 0.1 g / mL were mixed, and the mixture was stirred at 50°C for 1 h to obtain a casting solution;

[0059] c, all the casting solution obtained in step b was poured into a culture dish and placed in an oven at 40°C for 4 h to obtain a biomass composite film material of carbon quantum dot B composite carboxymethyl cellulose.

[0060] Figure 4The photos of carbon quantum dots B composite carboxymethyl cellulose film under natural light and ultraviolet light conditions show that the film has good transparency, no color under natural light, but presents obvious bright blue under ultraviolet light, and has obvious photoluminescence characteristics, which provides feasibility for subsequent pollutant detection.

[0061] Figure 5 The contact angle of the composite film changes with the CO2 flow rate from small to large. As can be seen from the figure, with the increase of CO2 flow rate, the contact angle of the film gradually increases, and the hydrophobicity gradually increases, achieving the purpose of dynamically adjusting the hydrophilic and hydrophobic properties of the film by using CO2. In addition, the water flux and porosity of the composite film under different CO2 gas flow rates were measured by using a vacuum pump and a filtration device according to the mass method, and the experimental results are shown in Table 1.

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

[0063] Sample CO2 flow rate (mL min -1 ) Porosity (%) 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] As can be seen from the above table, the composite film shows significantly different water flux under different gas flow rates, which shows that the film has a corresponding dynamic response under the stimulation of CO2. This may be due to the protonation of the abundant hydroxyl groups at the chain end of the cellulose composite film under the stimulation of CO2, and the film changes from a tight and closed state to an extended state with a large number of microporous structures, thereby increasing the water flux.

[0065] The carbon quantum dots B composite carboxymethyl cellulose film was applied to the simultaneous detection of industrial wastewater and the adsorption treatment of pollutants bisphenol A, and the specific operation was as follows:

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

[0067] (2), take 2 g of carbon quantum dots B composite carboxymethyl cellulose film, add to 20 g of unknown concentration of bisphenol A wastewater sample to be tested, in a 50 °C constant temperature water bath oscillator for adsorption treatment, through the adsorption of pollutants combined with the observed color change of the mixed solution under ultraviolet light irradiation qualitative determination, when the color no longer changes and stable 2 min after adsorption reaches equilibrium, end the experiment.

[0068] After the film is taken out of the wastewater sample and dried, the concentration of bisphenol A in the film is measured by fluorescence spectrophotometry, and the adsorption rate of the film to bisphenol A in wastewater is quantitatively calculated as 98.4%.

[0069] Example 3

[0070] The CO2-responsive carbon quantum dots are prepared from morpholine-4-yl acetic acid and polyethylene glycol 200 at a molar ratio of 1:1, and the following steps are followed:

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

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

[0073] A bio-based composite film of carbon quantum dots C composite lignin (dealkalized) is prepared using the above carbon quantum dot solution and lignin (dealkalized), and the preparation is as follows:

[0074] a, take 0.8 g of raw 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 dots C solution with a concentration of 0.1 g / mL after adding solvent water, stir at 30 °C until the mixture is uniform, and obtain a casting solution;

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

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

[0078] (1) Establishing standard curve. First, prepare bisphenol A standard solution with concentrations of 5 μg / L, 10 μg / L, 30 μg / L, 50 μg / L and 100 μg / L respectively; then immerse a circular carbon quantum dot C composite lignin film with a diameter of 2 cm in 100 mL of bisphenol A standard solution with different concentrations, and observe the color change of the film under ultraviolet light. It is found that with the increase of the concentration of bisphenol A solution, 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°C. Determine the fluorescence intensity by using a fluorescence spectrophotometer, and the standard curve of the relationship between the concentration of bisphenol A and the fluorescence intensity is linear, the detection range is 5-100 μg / L, and the detection limit is 0.91 μg / L, which proves that the composite film has good detection performance for bisphenol A.

[0079] (2) Take 2 g of carbon quantum dot C composite lignin film and add it to 20 g of unknown concentration bisphenol A wastewater sample, and perform adsorption treatment in a 50°C constant temperature water bath oscillator. Qualitative determination is made by combining the adsorption of pollutants with the color change of the mixed solution observed under ultraviolet light. When the color no longer changes and stabilizes for 2 min, the adsorption reaches equilibrium, and the experiment ends.

[0080] After the film is taken out of the wastewater sample and dried, the concentration of bisphenol A on the film is determined by fluorescence spectrophotometry, and the adsorption rate of the film for bisphenol A in wastewater is quantitatively calculated as 93.8%.

[0081] Example 4

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

[0083] S1, uniformly mix 0.03 mol of 4-aminomorpholine and 0.01 mol of polyethylene glycol 400, then take 1 g of the mixture and add it to 40 mL of water, heat to 180°C in a hydrothermal reactor for 12 h, filter after the reaction is completed, and 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-carboxamidyl)-1H-imidazole, and react under the conditions of heating at 80°C and stirring for 0.5 h to obtain a carbon quantum dot D solution.

[0085] A bio-based composite film of carbon quantum dot D composite carboxymethyl cellulose is prepared using the above carbon quantum dot solution and carboxymethyl cellulose according to the following steps:

[0086] a, take 0.8 g of raw material carboxymethyl cellulose, dissolve it in 50 mL of deionized water to obtain a carboxymethyl cellulose solution with a concentration of 0.016 g / mL;

[0087] b. 10 g of carboxymethyl cellulose solution and 1 g of carbon quantum dots D solution with a concentration of 0.1 g / mL were mixed in solvent water, stirred at 30°C for 1 h until uniform, to obtain a casting solution;

[0088] c. All the casting solution obtained in step b was poured into a culture dish and placed in an oven at 40°C for 4 h to obtain a bio-based composite film material of carbon quantum dots D composite carboxymethyl cellulose.

[0089] The carbon quantum dots D composite carboxymethyl cellulose film was applied to the simultaneous detection of industrial wastewater and the adsorption treatment of pollutants bisphenol A, and the specific operation was as follows:

[0090] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5 μg / L, 10 μg / L, 30 μg / L, 50 μg / L, and 100 μg / L, respectively; then immerse a circular carbon quantum dots D composite carboxymethyl cellulose film with a diameter of 2 cm in 100 mL of bisphenol A standard solution 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 half an hour, the film was taken out and dried in an oven at 40°C. The fluorescence intensity was determined by fluorescence spectrophotometry, and the standard curve of the relationship between the concentration of bisphenol A and the fluorescence intensity showed a linear relationship, the detection range was 5-100 μg / L, and the detection limit was 5.66 μg / L, which proved that the composite film had good detection performance for bisphenol A.

[0091] (2) Take 2 g of carbon quantum dots D composite carboxymethyl cellulose film and add it to 20 g of unknown concentration bisphenol A wastewater sample, and perform adsorption treatment in a 50°C constant temperature water bath shaker. Qualitative determination was made by combining the adsorption of pollutants with the color change of the mixed solution observed directly under ultraviolet light. When the color no longer changed and stabilized for 2 min, the adsorption reached equilibrium and the experiment ended.

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

[0093] Example 5

[0094] CO2-responsive carbon quantum dots were prepared from 4-acetyl morpholine and polyethylene glycol 200 at a molar ratio of 2:1, and the operation was as follows:

[0095] S1, 0.02 mol 4-acetyl morpholine and 0.01 mol polyethylene glycol 200 were mixed uniformly, then 1 g of the mixture was added to 20 mL water, heated to 200°C in a hydrothermal reactor for 14 h, and then filtered to obtain a precursor solution.

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

[0097] The carbon quantum dot E composite chitosan bio-based composite film was prepared using the above carbon quantum dot solution and chitosan, and the preparation was as follows:

[0098] a, 0.8 g of raw material chitosan was dissolved in 50 mL N,N-dimethylformamide to obtain a chitosan solution with a concentration of 0.016 g / mL;

[0099] b, 10 g of the chitosan solution and 1 g of the carbon quantum dot E solution with a concentration of 0.1 g / mL after adding solvent water were mixed and stirred at 30°C for 1 h until they were mixed uniformly to obtain a casting solution;

[0100] c, all the casting solution obtained in step b was poured into a culture dish and placed in an oven for drying at 40°C for 4 h to obtain a carbon quantum dot E composite chitosan bio-based composite film material.

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

[0102] (1) Establish a standard curve. First, prepare bisphenol A standard solutions with concentrations of 5 μg / L, 10 μg / L, 30 μg / L, 50 μg / L and 100 μg / L; then immerse a circular carbon quantum dot E composite chitosan film with a diameter of 2 cm in 100 mL of bisphenol A standard solution 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. The film was taken out after half an hour of soaking and dried in an oven at 40°C. The fluorescence intensity was determined by a fluorescence spectrophotometer, and the standard curve of the relationship between the concentration of bisphenol A and the fluorescence intensity showed a linear relationship, the detection range was 5-100 μg / L, and the detection limit was 2.5 μg / L, which proved that the composite film had good detection performance for bisphenol A.

[0103] (2), take 2 g carbon quantum dots E composite chitosan film, added to 20 g of the unknown concentration of bisphenol A wastewater sample, in 50 °C constant temperature water bath oscillator adsorption treatment, by the adsorption of pollutants combined with direct observation of the color change of the mixed solution under ultraviolet light irradiation do qualitative determination, when the color no longer change and stable 2 min after adsorption to balance, end the experiment.

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

[0105] Comparative Example 1

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

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

[0108] The composite film of the comparative example has general detection performance for bisphenol A, which is significantly inferior to Example 2. This may be due to the fact that the raw material 4-acetyl morpholine in Example 2 has rich amide groups, which is a typical hydrogen bond acceptor structure. The unpaired electrons of the C=O bond on the amide can provide electrons, which can effectively accept the hydrogen provided by the hydroxyl group in the structure of bisphenol A as a hydrogen bond donor. Under the action of this hydrogen bond, Example 2 using 4-acetyl morpholine as the raw material can efficiently and accurately identify bisphenol A in wastewater. The raw material N-methyl morpholine selected in this comparative example is substituted 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 reduces the number and performance of the original hydrogen bond acceptors in the morpholine structure, resulting in a significant decrease in the possibility of the carbon quantum dots prepared in this comparative example to interact with bisphenol A, and a decrease in detection performance. The adsorption performance is also reduced, which may also be caused by the reduction of amine active functional groups.

[0109] Comparative Example 2

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

[0111] The composite film was applied to the process of simultaneous detection and adsorption treatment of pollutants bisphenol A in industrial wastewater according to the same method as Example 2. The results showed that the detection range of the film was 5-100 μg / L, the detection limit was 6.99 μg / L, and the composite film had good detection performance for bisphenol A. However, the adsorption rate of bisphenol A was significantly reduced, only 60.7%, which may be due to the obvious difference between the raw material benzimidazole in this comparative example and the 1-(1H-imidazole-1-carboxamidyl)-1H-imidazole used in Example 2. The difference in the action of these functional groups with CO2 leads to the difference in the adsorption performance of bisphenol A. First, the imidazole group plays a CO2 response role in material preparation. Example 2 has two imidazole groups, which can increase the probability of precursor interaction with CO2 and the amount of CO2 introduced, and then better participate in the adjustment of the film structure in the subsequent composite film preparation, resulting in a film with excellent performance. In addition, the 1-(1H-imidazole-1-carboxamidyl)-1H-imidazole in Example 2 also has a highly reactive amine group, which can further increase the adsorption active site of the composite film. In this comparative example, benzimidazole not only lacks CO2 functional groups that can adjust the film, but also introduces phenyl groups that cannot serve as adsorption sites, and has certain biological toxicity, which may cause environmental pollution.

[0112] Comparative Example 3

[0113] The CO2-responsive carbon quantum dot composite bio-based film provided by the comparative example has a preparation method 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, and the rest is exactly the same. The specific operation is not described again.

[0114] The composite film was applied to the process of simultaneous detection and adsorption treatment of pollutants bisphenol A in industrial wastewater according to the same method as Example 2. The results showed that the detection range of the film was 5-100 μg / L, the detection limit was 15.6 μg / L, the detection performance of the composite film for bisphenol A was reduced, and the adsorption rate of bisphenol A was significantly reduced, only 38.6%. It can be seen that the adaptability of the film and the CO2-responsive carbon quantum dots will directly affect the adsorption treatment performance. In addition, from the perspective of environmental protection, the selected bio-based raw material is more green, and the cost is low, the source is wide, and it is more in line with the requirement of waste treatment with waste.

[0115] In summary, the carbon quantum dots have CO2 response function, linear fluorescence quenching phenomenon for bisphenol A, and can provide active site to enhance the adsorption performance of the membrane, and can be used as detection material and adsorption material for 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 application of bisphenol A pollution treatment of industrial wastewater, solve the problem of low adsorption efficiency of membrane separation bisphenol A, make up the steps of needing large instruments, complicated operation and being difficult to monitor in real time in the detection process of bisphenol A, and the composite film also has the advantages of wide raw material source, low cost and green environmental protection, and has broad prospects in economic, environmental and social benefits.

[0116] Please note that the technical features of the above embodiments can be combined in any manner, and in order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, it should be considered that they are within the scope of the present application. The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. Carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A, characterized by: The carbon quantum dots are prepared by a solvothermal reaction of morpholine and / or morpholine derivatives and polyethylene glycol to obtain a precursor solution, and then a heating reaction of the precursor solution and an amine-based imidazole compound. The morpholine and / or morpholine derivatives include at least one of morpholine, 4-acetylmorpholine, 4-aminomorpholine and morpholine-4-yl acetic acid. The solvothermal reaction is performed at a temperature of 180-220 DEG C for 8-12 hours. The heating reaction is performed at a temperature of 40-80 DEG C for 0.5-2 hours.

2. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized by: The polyethylene glycol includes at least one of polyethylene glycol 200 and polyethylene glycol 400; and / or the amine-based imidazole compound includes at least one of 2-aminoimidazole, 4-amino-5-imidazole formamide, 5-azabenzimidazole and 1-(1H-imidazole-1-carboxamidyl)-1H-imidazole. 3.The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized by: The molar ratio of morpholine and / or morpholine derivatives to polyethylene glycol is 3:1-9. 4.The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to claim 1, characterized by: In the precursor solution, the total mass of solutes morpholine, morpholine derivatives and polyethylene glycol is in a ratio of 1g:20-40mL to the solvent water; and / or the mass ratio of the precursor solution to the amine-based imidazole compound is 4:1-10.

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

6. The carbon quantum dots for simultaneous detection and adsorption treatment of bisphenol A according to any one of claims 1 to 5, characterized by: As an effective substance for detecting and / or adsorbing bisphenol A, the carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

7. A bio-based composite film, characterized by: The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

8. The bio-based composite film according to claim 7, wherein: The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

9. The bio-based composite film according to claim 8, wherein: The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

10. The method for preparing the bio-based composite thin film as described in claim 8 or 9, characterized in that, The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

11. The method of claim 10, wherein the biobased composite film is prepared by: The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A.

12. Use of a bio-based composite film according to any one of claims 7-9, characterized in that: The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. 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The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum dots are used for preparing a detection material and an adsorption material for bisphenol A. The carbon quantum

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