Cadmium ion imprinting-quantum dot composite bagasse biochar as well as preparation method and application thereof

Abstract

The invention provides cadmium ion imprinting-quantum dot composite bagasse biochar as well as a preparation method and application thereof. According to the preparation method of the cadmium ion imprinting-quantum dot composite bagasse biochar, the bagasse biochar is taken as a matrix, and a surface imprinting method is combined with CdSe quantum dots to prepare a composite material BM-Cd-iip / CdSe with efficient adsorption and fluorescence detection functions, and the composite material BM-Cd-iip / CdSe is suitable for cadmium pollution treatment and detection; the bagasse biochar serving as a matrix has the characteristics of high specific surface area and porous structure after being activated by acid, and the adsorption capacity and selectivity of cadmium ions are improved by combining high-selectivity adsorption sites of an ion imprinting technology; the quantum dots are introduced to endow the material with fluorescence characteristics, and rapid and sensitive detection of cadmium ions can be realized through fluorescence intensity change.

Description

Technical Field

[0001] This invention relates to the field of biosorbent materials technology, and in particular to a cadmium ion imprinted-quantum dot composite sugarcane bagasse biochar, its preparation method, and its application. Background Technology

[0002] Cadmium, a highly toxic heavy metal, is widely found in industrial wastewater from metallurgy, electroplating, and battery manufacturing. Its environmental residues can lead to water and soil pollution and accumulate through the food chain, seriously threatening human health and causing diseases such as kidney damage, osteoporosis, and cancer. Currently, there is an urgent need for efficient, economical, and environmentally friendly solutions for cadmium pollution control. Traditional cadmium pollution control technologies, such as chemical precipitation, ion exchange, and physical adsorption, have significant limitations: chemical precipitation easily generates secondary pollution; ion exchange materials are expensive and difficult to regenerate; and conventional adsorbents (such as activated carbon) have limited selectivity and adsorption capacity for cadmium ions, making it difficult to meet the needs of complex wastewater systems.

[0003] Biochar, as an environmentally friendly adsorbent material, has become a research hotspot in the field of heavy metal adsorption due to its porous structure, high specific surface area, and abundant surface functional groups (such as hydroxyl and carboxyl groups). Traditional biochar raw materials mostly use straw, wood residues, or shell biomass, but their application is limited by the seasonal supply of raw materials, pretreatment costs, and insufficient adsorption performance. For example, straw-based biochar is affected by the agricultural cycle, making raw material availability unstable; wood-based biochar requires high-temperature pyrolysis, resulting in high energy consumption; while shell biomass (such as peanut shells and walnut shells), although possessing a natural porous structure, has a limited specific surface area, requiring complex modification to improve its performance. Sugarcane bagasse, as a major byproduct of the sugar industry, has a huge annual output and is often discarded or incinerated, causing not only resource waste but also exacerbating environmental pollution. However, sugarcane bagasse, due to its unique fibrous structure and chemical composition (rich in cellulose, hemicellulose, and lignin), exhibits significant advantages in biochar preparation.

[0004] Furthermore, current biochar adsorbent materials can only adsorb cadmium ions and do not have the function of cadmium ion detection. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, its preparation method, and its applications. The preparation method of this invention combines quantum dots, biomass, and ion imprinting technology. Sugarcane bagasse, as an agricultural waste, is widely available and inexpensive; its natural fibrous structure, after modification, can form a high specific surface area carrier. The ion-imprinted layer significantly enhances the specific adsorption capacity for cadmium, while the introduction of quantum dots enables real-time fluorescence monitoring of the adsorption process.

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

[0007] In a first aspect, the present invention provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, comprising the following steps:

[0008] After crushing the sugarcane bagasse, it was calcined under an inert atmosphere to obtain the carbonized product.

[0009] The carbonized product was soaked in an acid solution, washed, and dried to obtain biochar powder.

[0010] Biochar powder was mixed with CdCl2 and ethanol, then 3-mercaptopropyltrimethoxysilane was added, shaken, then azobisisobutyronitrile and epichlorohydrin were added, reacted, washed, and dried to obtain the intermediate product.

[0011] CdCl2 and C3H6O2S were dissolved in water and stirred. Then, ammonia was added dropwise until the solution became turbid and then clear, resulting in solution A. SeCl4 was dissolved in water to obtain solution B. Solution B was added to solution A and the mixture was refluxed. The reaction products were washed and dispersed in water to obtain an aqueous solution of CdSe quantum dots.

[0012] The intermediate product was mixed with an aqueous solution of CdSe quantum dots and dried to obtain cadmium ion imprinted-quantum dot composite bagasse biochar.

[0013] Preferably, the sugarcane bagasse is crushed, passed through a 30-90 mesh sieve, and calcined at 600-700℃ for 2-4 hours under an inert atmosphere to obtain the carbonized product.

[0014] Preferably, the carbonized product is soaked in an acid solution, washed until neutral, and dried to obtain biochar powder;

[0015] The acid solution is HCl with a concentration of 6–10 mol / L, the soaking time is 6–10 h, and the mass ratio of biochar powder to acid solution is (3–5):20.

[0016] Preferably, biochar powder is mixed with CdCl2 and ethanol, then 3-mercaptopropyltrimethoxysilane is added, and the mixture is shaken at 100-150 r / min for 1-3 h at 40-60 °C. Then azobisisobutyronitrile and epichlorohydrin are added, and the mixture is shaken and reacted for another 16-24 h. The mixture is then washed and dried to obtain the intermediate product.

[0017] Preferably, solution B is added to solution A, and the mixture is refluxed at 80–100°C for 1–2 hours. The reaction product is then washed and dispersed in water to obtain an aqueous solution of CdSe quantum dots.

[0018] Preferably, the mass ratio of the biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile, and epichlorohydrin is (4-6):1:(80-100):(2-3):(0.1-0.2):(10-12).

[0019] Preferably, in the step of dissolving CdCl2 and C3H6O2S in water, the molar ratio of CdCl2, C3H6O2S and water is (1-3):1:(2-4);

[0020] And / or, in the step of adding solution B to solution A, the volume ratio of solution A to solution B is 1:(1~3);

[0021] And / or, in the step of mixing the intermediate product with the CdSe quantum dot aqueous solution, the mass ratio of the intermediate product to the CdSe quantum dot aqueous solution is (60-80):1, and the mass fraction of the CdSe quantum dot aqueous solution is 47.5%-76.3%;

[0022] In the step of dissolving CdCl2 and C3H6O2S in water, stirring, and then adding ammonia dropwise until the solution is first turbid and then clear, to obtain solution A, the mass fraction of ammonia is 25-28% and the volume ratio of water to ammonia is (2-3):1.

[0023] And / or, the inert atmosphere includes at least one of nitrogen, helium, neon, and argon.

[0024] Secondly, the present invention also provides a cadmium ion imprinted-quantum dot composite sugarcane bagasse biochar, which is prepared using the aforementioned preparation method.

[0025] Thirdly, the present invention also provides a method for preparing cadmium ion-imprinted quantum dot composite bagasse biochar by the method described above, or the application of the cadmium ion-imprinted quantum dot composite bagasse biochar in removing cadmium ions from water.

[0026] Preferably, in the aforementioned application, the pH of the water is 2 to 9.

[0027] The cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, its preparation method, and its application of the present invention have the following advantages compared with the prior art:

[0028] This invention discloses a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar. Using sugarcane bagasse biochar as a matrix, CdSe quantum dots are combined via surface imprinting to obtain a composite material BM-Cd-iip / CdSe that combines highly efficient adsorption and fluorescence detection functions, suitable for cadmium pollution control and detection. The sugarcane bagasse biochar matrix, after acid activation, exhibits high specific surface area and a porous structure. Combined with the highly selective adsorption sites of ion imprinting technology, the adsorption capacity and selectivity for cadmium ions are enhanced. The introduction of quantum dots imparts fluorescence properties to the material, enabling rapid and sensitive detection of cadmium ions through changes in fluorescence intensity. This invention combines quantum dots, biomass, and ion imprinting technology. Sugarcane bagasse, as an agricultural waste, is widely available and inexpensive; its natural fibrous structure can be modified to form a high specific surface area carrier. The ion-imprinted layer significantly enhances the specific adsorption capacity for cadmium, while the introduction of quantum dots enables real-time fluorescence monitoring of the adsorption process. This synergistic design not only overcomes the shortcomings of traditional materials with limited functionality but also combines environmental friendliness and economic efficiency, providing an innovative approach to cadmium pollution control and detection. This invention combines cadmium ion imprinting technology with quantum dot fluorescence detection using sugarcane bagasse as a matrix to develop a composite material with both strong adsorption capacity and real-time monitoring capability. Specific adsorption sites for cadmium ions are precisely constructed on sugarcane bagasse biochar using ion imprinting, significantly improving adsorption selectivity and capacity; simultaneously, CdSe quantum dots are composited, utilizing their fluorescence properties to determine changes in cadmium ion concentration. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a SEM image of untreated sugarcane bagasse from Example 2;

[0031] Figure 2 SEM image of modified sugarcane bagasse (i.e., the intermediate product prepared in step S3 of Example 2);

[0032] Figure 3 The graph shows the relative fluorescence intensity of the cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar prepared in Example 2 as a function of cadmium ion concentration in solutions of different concentrations. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0034] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0035] This invention provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, comprising the following steps:

[0036] S1. After crushing the sugarcane bagasse, calcine it under an inert atmosphere to obtain the carbonized product;

[0037] S2. The carbonized product is soaked in an acid solution, washed, and dried to obtain biochar powder (steps S1 to S2 are sugarcane bagasse pretreatment and acid activation).

[0038] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane (i.e., γ-mercaptopropyltrimethoxysilane), shake, and then add azobisisobutyronitrile (chemical formula C8H). 12 N4) reacts with epichlorohydrin (C3H5ClO), washes, and dries to obtain an intermediate product (step S3 is the construction of a cadmium ion imprinted layer);

[0039] S4. Dissolve CdCl2 and C3H6O2S (3-mercaptopropionic acid) in water, stir, and then add ammonia dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain solution B; add solution B to solution A, reflux the reaction, wash the reaction product and disperse it in water to obtain an aqueous solution of CdSe quantum dots (step S4 is the synthesis of CdSe quantum dots);

[0040] S5. Mix the intermediate product with an aqueous solution of CdSe quantum dots and dry to obtain cadmium ion imprinted-quantum dot composite bagasse biochar (step S5 is the composite of quantum dots and intermediate product).

[0041] This invention discloses a method for preparing cadmium ion-imprinted-quantum dot composite bagasse biochar. The method uses bagasse biochar as a matrix and combines it with CdSe quantum dots via surface imprinting to obtain a composite material BM-Cd-iip / CdSe that combines efficient adsorption and fluorescence detection functions, suitable for cadmium pollution control and detection. The bagasse biochar matrix, after acid activation, exhibits high specific surface area and a porous structure. Combined with the highly selective adsorption sites of ion imprinting technology, the adsorption capacity and selectivity for cadmium ions are enhanced. The introduction of quantum dots imparts fluorescence properties to the material, enabling rapid and sensitive detection of cadmium ions through changes in fluorescence intensity.

[0042] This invention combines quantum dots, biomass, and ion imprinting technology. Sugarcane bagasse, as an agricultural waste, is widely available and inexpensive. Its natural fibrous structure, after modification, can form a high specific surface area carrier. The ion-imprinted layer can significantly enhance the specific adsorption capacity for cadmium, while the introduction of quantum dots enables real-time fluorescence monitoring of the adsorption process. This synergistic design not only overcomes the shortcomings of traditional materials with limited functionality but also combines environmental friendliness and economic efficiency, providing an innovative approach to cadmium pollution control and detection. This invention uses sugarcane bagasse as a matrix to combine cadmium ion imprinting technology with quantum dot fluorescence detection, developing a composite material with both strong adsorption capacity and real-time monitoring capability. This invention first uses ion imprinting technology to adsorb cadmium... 2+ Using Cd as the template ion, an imprinted polymer layer is formed on the surface of biochar through a functional monomer (3-mercaptopropyltrimethoxysilane) and a crosslinking agent (epoxychloropropane). 2+ After being washed away, what remains is Cd 2+ "Imprinted cavities" with highly matched size, shape, and coordination structures. When materials come into contact with Cd-containing... 2+ In solutions containing Cd, the cavity selectively captures Cd through its unique cavity radius. 2+ Other interfering ions (such as Pb) 2+ Cu 2+This invention addresses the issue of cadmium ion rejection due to mismatch. It modifies quantum dots with 3-mercaptopropionic acid ligands to give them a specific response to cadmium ions. Furthermore, cadmium ion-imprinted cavities constructed on the surface of bagasse biochar selectively enrich cadmium ions, causing a localized increase in cadmium ion concentration around the quantum dots, thereby amplifying fluorescence signal changes for cadmium ion detection. By precisely constructing cadmium ion-specific adsorption sites on bagasse biochar using ion imprinting, the adsorption selectivity and capacity are significantly improved. Simultaneous composite CdSe quantum dots are used to determine changes in cadmium ion concentration based on their fluorescence properties. The preparation process of this invention adheres to green chemistry principles: agricultural waste raw materials are utilized resourcefully, and low-temperature carbonization and controlled polymerization processes significantly reduce energy consumption; the materials exhibit excellent recyclability and can be recycled after simple processing. The entire technology balances environmental friendliness and economic feasibility, providing a sustainable solution for heavy metal pollution control. Due to its porous nature, bagasse may have some pores with pore sizes similar to the radius of cadmium ions, which can adsorb cadmium ions. However, since the pores are only similar, they cannot screen for cadmium ions and the adsorption efficiency is low. This invention can not only greatly improve the adsorption efficiency of cadmium ions, but also screen for cadmium ions, that is, only adsorb cadmium ions.

[0043] In some embodiments, sugarcane bagasse is crushed, passed through a 30-90 mesh sieve, and calcined at 600-700°C for 2-4 hours under an inert atmosphere to obtain a carbonized product.

[0044] In some embodiments, the carbonization product is soaked in an acid solution, washed until neutral, and dried to obtain biochar powder;

[0045] The acid solution is HCl with a concentration of 6–10 mol / L, the soaking time is 6–10 h, and the mass ratio of biochar powder to acid solution is (3–5):20.

[0046] In some embodiments, biochar powder is mixed with CdCl2 and ethanol, and then 3-mercaptopropyltrimethoxysilane is added. The mixture is shaken at 100-150 r / min for 1-3 h at 40-60 °C. Then, azobisisobutyronitrile and epichlorohydrin are added, and the mixture is shaken and reacted for another 16-24 h. The mixture is then washed and dried to obtain the intermediate product.

[0047] In some embodiments, solution B is added to solution A, and the mixture is refluxed at 80–100°C for 1–2 h. The reaction product is washed and dispersed in water to obtain an aqueous solution of CdSe quantum dots.

[0048] In some embodiments, the mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is (4-6):1:(80-100):(2-3):(0.1-0.2):(10-12).

[0049] In some embodiments, in the step of dissolving CdCl2 and C3H6O2S in water, the molar ratio of CdCl2, C3H6O2S and water is (1-3):1:(2-4). The molar amount of CdCl2 is 0.0036-0.0216 mol, and the molar amount of C3H6O2S is 0.0108 mol.

[0050] In some embodiments, in the step of adding solution B to solution A, the volume ratio of solution A to solution B is 1:(1-3).

[0051] In some embodiments, in the step of mixing the intermediate product with the CdSe quantum dot aqueous solution, the mass ratio of the intermediate product to the CdSe quantum dot aqueous solution is (60-80):1, and the mass fraction of the CdSe quantum dot aqueous solution is 47.5%-76.3%.

[0052] In some embodiments, CdCl2 and C3H6O2S are dissolved in water, stirred, and then ammonia is added dropwise until the solution becomes turbid and then clear to obtain solution A. In this step, the mass fraction of ammonia is 25-28%, and the volume ratio of water to ammonia is (2-3):1.

[0053] In some embodiments, the inert atmosphere includes at least one of nitrogen, helium, neon, and argon.

[0054] In some embodiments, sugarcane bagasse is crushed, passed through a 30-90 mesh sieve, and calcined at 600-700°C for 2-4 hours under an inert atmosphere at a rate of 5-10°C / min to obtain a carbonized product.

[0055] Based on the same inventive concept, the present invention also provides a cadmium ion imprinted-quantum dot composite bagasse biochar, which is prepared by the above-described preparation method.

[0056] Based on the same inventive concept, the present invention also provides an application of cadmium ion imprinted-quantum dot composite bagasse biochar or cadmium ion imprinted-quantum dot composite bagasse biochar prepared by the above preparation method in removing cadmium ions from water.

[0057] In some embodiments, when cadmium ion imprinted-quantum dot composite bagasse biochar is used to remove cadmium ions from water, the pH of the water is 2 to 9, such as when the pH of the water is 6.

[0058] This invention combines cadmium ion imprinting technology with quantum dot fluorescence detection using sugarcane bagasse as a matrix to develop a composite material with both strong adsorption capacity and real-time monitoring capability. Specific adsorption sites for cadmium ions are precisely constructed on sugarcane bagasse biochar using ion imprinting, significantly improving adsorption selectivity and capacity. Simultaneously, CdSe quantum dots are composited, utilizing their fluorescence properties to determine changes in cadmium ion concentration. The preparation process of this invention adheres to green chemistry principles: agricultural waste raw materials are utilized for resource recovery; low-temperature carbonization and controlled polymerization processes significantly reduce energy consumption; the material exhibits excellent recyclability and can be recycled after simple processing. The entire technology balances environmental friendliness and economic feasibility, providing a sustainable solution for heavy metal pollution control.

[0059] The following specific embodiments further illustrate the cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, its preparation method, and its application. This section further explains the invention with reference to specific embodiments, but should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in the art.

[0060] In the following examples, the bagasse is obtained from bagasse recycled from fruit farmers.

[0061] In the following examples, the method for calculating the cadmium removal rate R of cadmium in simulated wastewater by cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar is as follows:

[0062]

[0063] Wherein, C0: the initial concentration of cadmium ions (mg / L);

[0064] C e The remaining concentration of cadmium ions at adsorption equilibrium (mg / L);

[0065] R: The removal rate (%) of cadmium ions at adsorption equilibrium after 1 hour.

[0066] Example 1

[0067] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0068] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0069] S2. Immerse the carbonized product in 8 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0070] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0071] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 ml of water, stir, and then add 10 ml of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0072] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0073] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0074] The BM-Cd-iip / CdSe prepared in Example 1 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 1.1 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 97.8%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0075] Example 2

[0076] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0077] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0078] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0079] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0080] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 mL of water, stir, and then add 10 mL of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0081] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0082] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0083] The BM-Cd-iip / CdSe prepared in Example 2 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 0.75 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 98.5%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0084] Example 3

[0085] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0086] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0087] S2. Immerse the carbonized product in 10 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0088] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0089] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 ml of water, stir, and then add 10 ml of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0090] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0091] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0092] The BM-Cd-iip / CdSe prepared in Example 3 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 1.55 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 96.9%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0093] Example 4

[0094] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0095] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0096] S2. Immerse the carbonized product in 12 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0097] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0098] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 ml of water, stir, and then add 10 ml of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0099] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0100] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0101] The BM-Cd-iip / CdSe prepared in Example 4 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 2.3 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 95.4%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0102] In Examples 1-4, the hydroxyl and carboxyl groups on the surface of biochar are key functional groups for adsorbing cadmium ions, binding Cd ions through electrostatic attraction or complexation. 2+ However, in high concentrations of hydrochloric acid, these functional groups undergo protonation, leading to an increase in surface positive charge, which interacts with the positively charged Cd. 2+ Electrostatic repulsion occurs, significantly reducing adsorption efficiency. Excessive acid treatment may also damage the carbon skeleton structure of biochar, reducing its mechanical strength and chemical stability. The suitable hydrochloric acid concentration for this invention is 6 mol / L.

[0103] Example 5

[0104] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0105] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0106] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0107] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 5:1:90:2:0.1:10.

[0108] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 ml of water, stir, and then add 10 ml of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0109] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0110] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0111] The BM-Cd-iip / CdSe prepared in Example 5 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 1.40 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 97.2%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0112] Example 6

[0113] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0114] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0115] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0116] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 7:1:90:2:0.1:10.

[0117] S4. Dissolve 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:1) in 20 ml of water, stir, and then add 10 ml of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0118] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0119] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0120] The BM-Cd-iip / CdSe prepared in Example 6 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 1.55 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 96.7%, and the fluorescence detection sensitivity reached 0.01 μg / L.

[0121] In Examples 5 and 6, the template ion (Cd) 2+ Insufficient concentration of Cd leads to the functional monomer (3-mercaptopropyltrimethoxysilane) not being able to fully react with Cd. 2+The resulting imprint cavities are low in density and uneven in size. During adsorption, the cavities bind with Cd. 2+ The matching degree decreases, and the selective adsorption capacity weakens. Excess Cd 2+ This can cause template ions to accumulate on the surface of biochar, clogging pores. Simultaneously, the reaction sites between the crosslinking agent (epoxychloropropane) and the functional monomers are occupied, resulting in insufficient crosslinking degree of the imprinted layer and poor cavity stability. The cadmium ion imprinted-quantum dot composite bagasse biochar prepared with a biochar powder to CdCl2 mass ratio of 6:1 exhibited the highest cadmium ion removal rate.

[0122] Example 7

[0123] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0124] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0125] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0126] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0127] S4. Dissolve 0.0216 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio of 2:1) in 20 mL of water, stir, and then add 10 mL of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio of 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0128] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0129] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0130] The BM-Cd-iip / CdSe prepared in Example 7 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 0.75 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 98.5%, and the fluorescence detection sensitivity reached 0.02 μg / L.

[0131] Example 8

[0132] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0133] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0134] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0135] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0136] S4. Dissolve 0.0054 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:2) in 20 mL of water, stir, and then add 10 mL of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0137] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0138] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0139] The BM-Cd-iip / CdSe prepared in Example 8 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 0.75 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 98.5%, and the fluorescence detection sensitivity reached 0.017 μg / L.

[0140] Example 9

[0141] This embodiment provides a method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, including the following steps:

[0142] S1. After crushing the sugarcane bagasse, pass it through a 60-mesh sieve; take the sieve material and place it in a tube furnace, and calcine it at 650℃ for 3 hours under nitrogen protection at a rate of 5℃ / min to obtain the carbonized product.

[0143] S2. Immerse the carbonized product in 6 mol / L hydrochloric acid, with a mass ratio of carbonized product to hydrochloric acid of 5:20. Stir at 600 r / min for 8 hours. After acid leaching, neutralize with sodium bicarbonate solution to neutral pH, wash with water until no chloride ion residue remains, and dry at 60℃ to obtain biochar powder.

[0144] S3. Mix biochar powder with CdCl2 and ethanol, then add 3-mercaptopropyltrimethoxysilane, and shake at 100 r / min for 2 h at 50 °C. Then add azobisisobutyronitrile and epichlorohydrin, and continue shaking for 20 h. After the reaction is complete, wash three times with anhydrous ethanol and dry at 60 °C to obtain the intermediate product. The mass ratio of biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile and epichlorohydrin is 6:1:90:2:0.1:10.

[0145] S4. Dissolve 0.0036 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S) (CdCl2 and C3H6O2S molar ratio 1:3) in 20 mL of water, stir, and then add 10 mL of 28% ammonia water dropwise until the solution is initially turbid and then clear, to obtain solution A; dissolve SeCl4 in water to obtain 0.12 mol / L solution B; add solution B to solution A (the volume ratio of solution A to solution B is 1:3), reflux at 90 °C for 1 h, and centrifuge and wash the reaction product four times with a mixed solvent of acetone and ethanol (volume ratio 1:1), and then disperse it in water to obtain an aqueous solution of CdSe quantum dots;

[0146] S5. The intermediate product in S3 is mixed with a 0.06 mol / L CdSe quantum dot aqueous solution at a mass ratio of 60:1, ultrasonically dispersed for 1 hour, and dried at 60℃ to obtain the final product BM-Cd-iip / CdSe, which is cadmium ion imprinted-quantum dot composite bagasse biochar.

[0147] This embodiment also provides an application of cadmium ion imprinting-quantum dot composite sugarcane bagasse biochar in removing cadmium ions from water, specifically including:

[0148] The BM-Cd-iip / CdSe prepared in Example 9 was added to simulated wastewater containing cadmium ions (the initial concentration of cadmium ions in the wastewater was 50 mg / L, the concentration of cadmium ions after 1 h of adsorption was 0.75 mg / L, and the pH of the wastewater was 6). After adsorption equilibrium, the cadmium ion removal rate was measured to be 98.5%, and the fluorescence detection sensitivity reached 0.03 μg / L.

[0149] Cadmium ions (Cd) 2+ When the concentration is too high, the free Cd in the reaction system 2+Excessive amounts of thiol ligands lead to an excessively rapid quantum dot nucleation rate and uncontrolled crystal growth. The resulting quantum dots exhibit a wider size distribution, increased surface defects, and induce nonradiative recombination, resulting in a decrease in fluorescence quantum yield. Excessive thiol ligands (-SH) form an excessively thick surface passivation layer, hindering electronic coupling between the quantum dot nucleus and the external environment, thus suppressing fluorescence response. Simultaneously, increased steric hindrance between ligands leads to decreased quantum dot dispersion, making them prone to aggregation into large particles, triggering fluorescence quenching. The suitable molar ratio of CdCl2 to C3H6O2S in this invention is 1:1, i.e., 0.0108 mol of CdCl2 and 0.0108 mol of 3-mercaptopropionic acid (C3H6O2S).

[0150] Figure 1 This is a SEM image of untreated bagasse from Example 2;

[0151] Figure 2 This is a SEM image of modified sugarcane bagasse (i.e., the intermediate product prepared in step S3 of Example 2).

[0152] from Figures 1-2 As can be seen, sugarcane bagasse powder with varying pore sizes can be processed by the ion imprinting technology of this invention to obtain pore sizes consistent with the radius of cadmium ions, thereby greatly improving the ability to adsorb cadmium ions. Furthermore, cadmium ions can be screened for adsorption through the functional group interaction of the imprinted cavity and electrostatic adsorption.

[0153] Figure 3 The linear relationship between relative fluorescence intensity and cadmium ion concentration is shown in the curve. Specifically, the final product BM-Cd-iip / CdSe from Example 2 was placed in cadmium ion solutions of different concentrations, and the change in quantum dot fluorescence intensity was measured after stabilization (approximately 10 minutes). The detection limit and linear range of cadmium ions were calculated by plotting relative fluorescence intensity versus cadmium ion concentration, and a standard curve was plotted. The cadmium ion concentration was 10... -11 ~6.0×10 -7 .like Figure 3 As shown, within a continuous range of 0.01 μg / L to 1 μg / L, the relative fluorescence intensity of the quantum dots exhibits a linear relationship with the cadmium ion concentration. When the signal-to-noise ratio is 3, i.e., the relative fluorescence intensity is 1.2, the detection limit of the cadmium ion imprinted-quantum dot composite sugarcane bagasse biochar BM-Cd-iip / CdSe of the present invention is 0.01 μg / L.

[0154] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, 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.

[0155] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, characterized in that, Includes the following steps: After crushing the sugarcane bagasse, it was calcined under an inert atmosphere to obtain the carbonized product. The carbonized product was soaked in an acid solution, washed, and dried to obtain biochar powder. Biochar powder was mixed with CdCl2 and ethanol, then 3-mercaptopropyltrimethoxysilane was added, shaken, then azobisisobutyronitrile and epichlorohydrin were added, reacted, washed, and dried to obtain the intermediate product. CdCl2 and C3H6O2S were dissolved in water and stirred. Then, ammonia was added dropwise until the solution became turbid and then clear, resulting in solution A. SeCl4 was dissolved in water to obtain solution B. Solution B was added to solution A and the mixture was refluxed. The reaction products were washed and dispersed in water to obtain an aqueous solution of CdSe quantum dots. The intermediate product was mixed with an aqueous solution of CdSe quantum dots and dried to obtain cadmium ion imprinted-quantum dot composite bagasse biochar.

2. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, After crushing the sugarcane bagasse, pass it through a 30-90 mesh sieve and calcine it at 600-700℃ for 2-4 hours under an inert atmosphere to obtain the carbonized product.

3. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, The carbonized product was soaked in an acid solution, washed until neutral, and dried to obtain biochar powder. The acid solution is HCl with a concentration of 6–10 mol / L, the soaking time is 6–10 h, and the mass ratio of biochar powder to acid solution is (3–5):

20.

4. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, Biochar powder was mixed with CdCl2 and ethanol, and then 3-mercaptopropyltrimethoxysilane was added. The mixture was shaken at 100-150 r / min for 1-3 h at 40-60 °C. Then azobisisobutyronitrile and epichlorohydrin were added, and the mixture was shaken and reacted for another 16-24 h. The mixture was washed and dried to obtain the intermediate product.

5. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, Solution B was added to solution A and refluxed at 80–100 °C for 1–2 h. The reaction product was washed and dispersed in water to obtain an aqueous solution of CdSe quantum dots.

6. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, The mass ratio of the biochar powder, CdCl2, ethanol, 3-mercaptopropyltrimethoxysilane, azobisisobutyronitrile, and epichlorohydrin is (4-6):1:(80-100):(2-3):(0.1-0.2):(10-12).

7. The method for preparing cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar as described in claim 1, characterized in that, In the step of dissolving CdCl2 and C3H6O2S in water, the molar ratio of CdCl2, C3H6O2S and water is (1-3):1:(2-4); And / or, in the step of adding solution B to solution A, the volume ratio of solution A to solution B is 1:(1~3); And / or, in the step of mixing the intermediate product with the CdSe quantum dot aqueous solution, the mass ratio of the intermediate product to the CdSe quantum dot aqueous solution is (60-80):1, and the mass fraction of the CdSe quantum dot aqueous solution is 47.5%-76.3%; In the step of dissolving CdCl2 and C3H6O2S in water, stirring, and then adding ammonia dropwise until the solution is first turbid and then clear, to obtain solution A, the mass fraction of ammonia is 25-28% and the volume ratio of water to ammonia is (2-3):

1. And / or, the inert atmosphere includes at least one of nitrogen, helium, neon, and argon.

8. A cadmium ion-imprinted-quantum dot composite sugarcane bagasse biochar, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 7.

9. The application of cadmium ion imprinted-quantum dot composite bagasse biochar prepared by any of the preparation methods described in claims 1 to 7, or the cadmium ion imprinted-quantum dot composite bagasse biochar described in claim 8, in the removal of cadmium ions from water.

10. The application as described in claim 9, wherein the pH of the water is 2 to 9.

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