Carbon quantum dot VOCs (volatile organic compounds) removal material derived from citrus fruit peel and application of carbon quantum dot VOCs removal material

Abstract

The invention provides a citrus fruit peel derived carbon quantum dot VOCs removal material and application thereof.The preparation method of the material comprises the following steps that S1, citrus fruit peel is cleaned, dried and cut up, and uniform fragments with the size being 1-5 mm are formed; s2, under the high-purity nitrogen atmosphere, the cut citrus fruit peel fragments are subjected to programmed temperature control calcination, the calcination temperature ranges from 500 DEG C to 800 DEG C, the calcination time ranges from 100 min to 300 min, and the heating rate ranges from 1 DEG C / min to 15 DEG C / min; s3, carrying out acid pickling on the calcined material by using 0.005 to 0.1 mol / L diluted hydrochloric acid for 30 to 60 minutes so as to remove impurities; s4, carrying out ball milling treatment on the pickled material for 60 to 1440 minutes at a ball milling speed of 200 to 2000 rpm, so as to obtain the VOCs removal material with the carbon quantum dots; citrus fruit peels are used for synthesizing the carbon quantum dot catalyst, so that the carbon quantum dot catalyst can oxidize indoor VOCs at room temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a carbon quantum dot VOCs removal material derived from citrus fruit peels and an application thereof. Background Art

[0002] In recent years, with the rapid development of the interior decoration industry, the extensive use of adhesives, paints and synthetic materials has led to the widespread presence of volatile organic compounds (VOCs) in indoor environments and their continued slow release. These VOCs pose a potential threat to human health, and long-term exposure to such environments may induce chronic diseases. Although window ventilation is a traditional means of reducing VOCs, its application is greatly limited in actual living environments, such as during noise interference or air conditioning use. Therefore, it is particularly important to develop efficient indoor VOCs removal technology. In chemical principles, oxygen in the air can react with VOCs to produce harmless CO2 and H2O, and this process is a spontaneous reaction in thermodynamics. However, due to the high stability of VOCs molecules, the oxidation reaction kinetics at room temperature are extremely slow, which is difficult to meet the needs of practical applications. To this end, the introduction of catalysts to reduce the activation energy of VOCs oxidation and accelerate the reaction process has become the key.

[0003] However, current VOCs oxidation catalysts and catalytic technologies have the following significant defects:

[0004] 1. High cost of precious metal catalysts: Precious metals such as platinum and palladium show excellent catalytic performance in many chemical reactions, but their scarcity leads to high prices. For large-scale VOCs oxidation treatment, the large-scale use of precious metal catalysts is economically unaffordable, limiting their widespread application;

[0005] 2. Strong dependence on photoelectric injection energy: Injecting energy into the catalytic reaction system through light or electricity can significantly increase the reaction rate. However, this method not only increases equipment costs and operating expenses, but may also cause the problem of increased by-products. In addition, the application of photoelectric catalytic technology is limited in certain indoor environments (such as areas without light sources or electricity);

[0006] 3. Residues of VOCs removal agents and health risks: Existing VOCs removal technologies on the market often use the method of spraying chemical reagents and then sealing the room. These reagents are often difficult to completely remove, and their residues may pose unknown risks to human health. The toxicity of some VOCs removal agents is even greater than the VOCs being removed, exacerbating the safety issues of use.

[0007] In view of the above records, the traditional VOCs removal methods have the disadvantages of high cost, low efficiency and environmental damage. Therefore, it is particularly important to develop an efficient, economical and environmentally friendly VOCs removal material. Summary of the invention

[0008] One of the purposes of the present invention is to provide a carbon quantum dot VOC removal material derived from citrus fruit peels, which has strong decomposition ability and catalytic performance for VOCs, is efficient, environmentally friendly and harmless to the human body, and has high VOC removal efficiency and strong practicality. The present invention uses citrus fruit peels to synthesize carbon quantum dot catalysts, which can oxidize indoor VOCs at room temperature. Within 3 days of the experiment, 92.8±5.1% of VOCs in the test box were removed.

[0009] The second purpose of the present invention is to provide an application system of carbon quantum dot VOCs removal material derived from citrus fruit peel in purification, which can effectively remove VOCs pollution without causing secondary pollution and has outstanding application effect.

[0010] To achieve the above object, the present invention provides a carbon quantum dot VOCs removal material derived from citrus fruit peels, and the preparation method of the material comprises the following steps:

[0011] S1: washing, drying and chopping citrus fruit peels into uniform pieces with a size of 1-5 mm;

[0012] S2: In a high-purity nitrogen atmosphere, the chopped citrus peel fragments are subjected to programmed temperature calcination at a temperature of 500-800°C, a time of 100-300 min, and a heating rate of 1-15°C / min;

[0013] S3: Use 0.005-0.1 mol / L dilute hydrochloric acid to pickle the calcined material for 30-60 min to remove impurities;

[0014] S4: ball milling the pickled material, with a ball milling time of 60-1440 min and a ball milling speed of 200-2000 rpm to obtain a carbon quantum dot VOCs removal material.

[0015] Optionally, the calcined and acid-washed materials are subjected to multi-stage screening to ensure that the size of the carbon quantum dots is uniform, which specifically includes the following steps:

[0016] S41: collecting the carbon quantum dot powder obtained after completing step S4;

[0017] S42: screening the collected powder through a series of sieves with different apertures, the apertures of the sieves decreasing in sequence, for example, sieves with 200 mesh to 1200 mesh may be used;

[0018] S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size;

[0019] S44: Repeat step S43 until the powder passes through the finest sieve to obtain carbon quantum dot powder of uniform size;

[0020] S45: Dry the sieved powder to remove surface moisture and ensure the stability and dispersibility of the powder.

[0021] Multi-stage screening is a physical separation process used to ensure that the obtained carbon quantum dots have a uniform size distribution. By gradually reducing the mesh size, carbon quantum dots of similar size can be gradually screened out, thereby improving the uniformity and catalytic performance of the material. Drying can be carried out using an oven, spray dryer or other drying equipment to adapt to different production scales and requirements.

[0022] Optionally, the surface of the carbon quantum dots is modified to enhance their catalytic activity and selectivity. The specific steps and methods are as follows:

[0023] a: Select modifiers: According to the required catalytic activity and selectivity, select appropriate modifiers, such as organic or inorganic compounds containing nitrogen, sulfur, oxygen and other functional groups, such as polyethyleneimine, citric acid, cysteine, glucose, etc.;

[0024] b: Prepare the modifier solution: dissolve the selected modifier in an appropriate solvent, such as deionized water, ethanol, acetone, etc., to form a uniform modifier solution. The concentration is determined according to the nature of the modifier and the desired degree of modification;

[0025] c: Mixing treatment: Add carbon quantum dot powder to the modifier solution and stir evenly to ensure that each quantum dot can fully contact with the modifier;

[0026] d: Reaction treatment: placing the mixed solution under suitable reaction conditions, such as stirring at room temperature for a certain period of time or reacting under heating conditions, to promote the chemical reaction or physical adsorption of the modifier and the surface of the carbon quantum dots;

[0027] e: Separation and collection: After the reaction is completed, the excess modifier and reaction by-products are removed by centrifugation, filtration or distillation, and the modified carbon quantum dots are collected;

[0028] f: Washing and drying: Use deionized water or corresponding solvents to wash the modified carbon quantum dots multiple times to remove the residual modifier on the surface, and then dry them by freeze drying, spray drying or hot air drying to obtain dry modified carbon quantum dot powder.

[0029] Surface modification is an important means of material modification. The surface properties of carbon quantum dots can be adjusted by introducing specific functional groups or molecules, thereby improving their activity and selectivity in specific catalytic reactions. The choice of modifiers and reaction conditions need to be optimized according to the target application and the required performance.

[0030] To achieve the above objectives, the present invention also provides an indoor VOCs purification system using the carbon quantum dot VOCs removal material derived from citrus fruit peels, including at least one sensor and an intelligent control system, including at least one sensor, a spraying module, an air circulation device and an intelligent control system, wherein the sensor is used to monitor the VOCs concentration in the indoor air in real time, the intelligent control system automatically adjusts the operating speed of the air circulation device according to the monitoring results, and the intelligent control system automatically adjusts the spraying module to spray an aqueous solution containing carbon quantum dot powder into the room according to the monitoring results.

[0031] To achieve the above objectives, the present invention also provides a method for using the carbon quantum dot VOCs removal material derived from citrus fruit peels, including applying it to the catalytic oxidation of indoor VOCs to reduce the indoor VOCs concentration, and the catalytic oxidation process is carried out at room temperature without the need for additional energy input.

[0032] To achieve the above objectives, the present invention also provides a safety assessment and environmentally friendly treatment method for the carbon quantum dot VOCs removal material derived from citrus fruit peel, including an assessment of the long-term stability of the material and its potential impact on human health, as well as recycling and harmless treatment of discarded composite materials. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention is clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0034] In view of the problems existing in the prior art, an embodiment of the present invention provides a carbon quantum dot VOCs removal material derived from citrus fruit peels, and a preparation method of the material comprises the following steps:

[0035] S1: Wash, dry and chop citrus fruit peels to form uniform pieces with a size of 1-5 mm; it should be noted that the white flesh part of the citrus fruit peel is taken.

[0036] S2: In a high-purity nitrogen atmosphere, the chopped citrus fruit peel fragments are subjected to programmed temperature-controlled calcination at a temperature of 500-800°C, a time of 100-300 min, and a heating rate of 1-15°C / min; it should be understood that the high-purity nitrogen atmosphere means that the nitrogen concentration is above 99.9%.

[0037] S3: Use 0.005-0.1 mol / L dilute hydrochloric acid to pickle the calcined material for 30-60 min to remove impurities;

[0038] S4: ball milling the pickled material, with a ball milling time of 60-1440 min and a ball milling speed of 200-2000 rpm to obtain a carbon quantum dot VOCs removal material.

[0039] In one embodiment, the calcined and acid-washed material is subjected to multi-stage screening to ensure that the size of the carbon quantum dots is uniform, specifically comprising the following steps:

[0040] S41: collecting the carbon quantum dot powder obtained after completing step S4;

[0041] S42: screening the collected powder through a series of sieves with different apertures, the apertures of the sieves decreasing in sequence, for example, sieves with 200 mesh to 1200 mesh may be used;

[0042] S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size;

[0043] S44: Repeat step S43 until the powder passes through the finest sieve to obtain a carbon quantum dot powder of uniform size; multi-stage screening is a physical separation process used to ensure that the obtained carbon quantum dots have a uniform size distribution. By gradually reducing the sieve aperture, carbon quantum dots of similar sizes can be gradually screened out, thereby improving the uniformity and catalytic performance of the material. In the present invention, the size of the carbon quantum dots can be screened to between 3-5nm through multi-stage screening; it is worth noting that the size of existing carbon quantum dots is between 1nm-10nm.

[0044] S45: Dry the sieved powder to remove surface moisture and ensure the stability and dispersibility of the powder. It is worth noting that the drying process can be carried out using an oven or a spray dryer. The oven or spray dryer has the characteristics of low cost, fast drying speed, uniform product and high thermal efficiency. Therefore, the use of an oven or a spray dryer can better ensure the stability and dispersibility of the powder. Of course, in order to adapt to different production scales and requirements, the drying process liquid is not limited to the use of an oven or a spray dryer.

[0045] In one embodiment, the surface of the carbon quantum dots is modified to enhance their catalytic activity and selectivity. The specific steps and methods are as follows:

[0046] a: Select modifiers: According to the required catalytic activity and selectivity, select appropriate modifiers, such as organic or inorganic compounds containing nitrogen, sulfur, oxygen and other functional groups, such as polyethyleneimine, citric acid, cysteine, glucose, etc.;

[0047] b: Prepare the modifier solution: dissolve the selected modifier in an appropriate solvent, such as deionized water, ethanol, acetone, etc., to form a uniform modifier solution. The concentration is determined according to the nature of the modifier and the desired degree of modification;

[0048] c: Mixing treatment: Add carbon quantum dot powder to the modifier solution and stir evenly to ensure that each quantum dot can fully contact with the modifier;

[0049] d: Reaction treatment: placing the mixed solution under suitable reaction conditions, such as stirring at room temperature for a certain period of time or reacting under heating conditions, to promote the chemical reaction or physical adsorption of the modifier and the surface of the carbon quantum dots;

[0050] e: Separation and collection: After the reaction is completed, the excess modifier and reaction by-products are removed by centrifugation, filtration or distillation, and the modified carbon quantum dots are collected;

[0051] f: Washing and drying: The modified carbon quantum dots are washed multiple times with deionized water or a corresponding solvent to remove the residual modifier on the surface, and then dried by freeze drying, spray drying or hot air drying to obtain a dried modified carbon quantum dot powder. There are a variety of metal ions in the peel of citrus fruits, such as Fe, Cu, Co, Mn, etc. It is worth noting that the carbon quantum dot powder in this embodiment is a carbon quantum dot powder containing certain metal ions, which can be used as an active site for catalyzing the oxidation and decomposition of VOCs.

[0052] Surface modification is an important material modification method. The surface properties of carbon quantum dots can be adjusted by introducing specific functional groups or molecules, thereby improving their activity and selectivity in specific catalytic reactions. The selection of modifiers and reaction conditions need to be optimized according to the target application and the required performance. The purpose of surface modification in the present invention is to introduce amino groups (-NH), carboxyl groups (-COOH), sulfenyl groups (-SH) and fluoro groups (-F). Among them, the introduction of amino groups (-NH) can increase the hydrophilicity of carbon quantum dots, provide additional active sites on carbon quantum dots, enhance the activity of catalytic reactions, and improve the selectivity of catalysts; the introduction of carboxyl groups (-COOH) can improve the dispersibility and stability of carbon quantum dots, while increasing the interaction with metal ions, which can enhance the performance of catalysts; the introduction of sulfenyl groups (-SH) can form strong metal-sulfur bonds, increase the stability of carbon quantum dots, and may improve the catalytic activity, which can improve the electron transfer ability of catalysts; the introduction of fluoro groups (-F) can increase the chemical stability of carbon quantum dots.

[0053] In view of the problems existing in the prior art, an embodiment of the present invention provides an indoor VOCs purification system using the carbon quantum dot VOCs removal material derived from citrus fruit peels, comprising at least one sensor, a spraying module, an air circulation device and an intelligent control system, wherein the sensor is used to monitor the VOCs concentration in the indoor air in real time, the intelligent control system automatically adjusts the running speed of the air circulation device according to the monitoring results, and the intelligent control system automatically adjusts the spraying module to spray an aqueous solution containing carbon quantum dot powder into the room according to the monitoring results. Specifically, the system comprises a spraying module, an air circulation device, a composite material, a sensor and an intelligent control system, wherein the air circulation device is the core part of the purification system, responsible for inhaling indoor air, and releasing it back into the room after purification treatment; the composite material is used as a filtering or purification medium in the air circulation device, and the carbon quantum dots on its surface have the ability to catalytically decompose VOCs; the sensor is used to monitor the VOCs concentration in the indoor air in real time, and can be an electrochemical sensor, a metal oxide semiconductor sensor or other types of VOCs detection sensors; the intelligent control system is a central processing unit, which is used to receive sensor data and automatically adjust the operating parameters of the air circulation device according to these data.

[0054] When working, the sensor detects the VOCs concentration in the indoor air in real time. The sensor converts the detected VOCs concentration into an electrical signal and sends it to the intelligent control system; the intelligent control system receives the signal from the sensor and compares it with the preset VOCs concentration threshold; if the VOCs concentration is lower than the preset threshold, the intelligent control system may reduce the operating speed of the air circulation device to save energy; if the VOCs concentration is higher than the preset threshold, the intelligent control system will increase the operating speed of the air circulation device to speed up the removal of VOCs; the intelligent control system controls the VOCs removal efficiency by adjusting the fan speed in the air circulation device or changing other related parameters (such as temperature, humidity, etc.); the system continuously monitors the VOCs concentration and continuously adjusts the operating parameters according to real-time data to form a closed-loop control system.

[0055] In response to the problems existing in the prior art, an embodiment of the present invention also provides a method for using the carbon quantum dot VOCs removal material derived from citrus fruit peels, including applying it to the catalytic oxidation of indoor VOCs to reduce the indoor VOCs concentration, and the catalytic oxidation process is carried out at room temperature without the need for additional energy input.

[0056] In response to the problems existing in the prior art, an embodiment of the present invention also provides a safety assessment and environmental protection treatment method for the carbon quantum dot VOCs removal material derived from citrus fruit peel as described, including an assessment of the long-term stability of the material and its potential impact on human health, as well as recycling and harmless treatment of discarded composite materials.

[0057] The following is a detailed description of the citrus fruit peel-derived carbon quantum dot VOCs removal material and its application by using specific embodiments:

[0058] Example 1: Preparation of carbon quantum dots for VOC removal from citrus peels

[0059] S1: Wash, dry and chop citrus peels to form uniform pieces with a size of 5 mm. The weight of the citrus peels used is 500 g, and after washing and drying, the obtained pieces weigh 450 g.

[0060] S2: In a high-purity nitrogen atmosphere, the chopped citrus peel fragments were subjected to programmed temperature calcination. The calcination temperature was set to 700°C, the calcination time was set to 200 min, and the heating rate was set to 5°C / min. After the calcination, the weight of the obtained doped carbon material was 150 g.

[0061] S3: The calcined material was pickled with 0.01 mol / L dilute hydrochloric acid for 45 min. After pickling, the weight of the obtained material was 130 g, and the impurity removal rate reached 90%.

[0062] S4: The pickled material is subjected to ball milling treatment, the ball milling time is 120 minutes, and the ball milling speed is 1000 rpm. The final carbon quantum dot VOCs removal material weighs 120 g, and the particle size distribution is between 5-10 nm.

[0063] Example 2: Application of indoor VOCs purification system

[0064] S1: In a closed laboratory environment, the initial VOCs concentration is 500 ppb and is treated using this purification system.

[0065] The experimental results showed that after 24 hours of treatment, the VOCs concentration dropped to 100 ppb and the removal rate was 80%.

[0066] Comparative Example

[0067] Comparative Example 1: Using traditional activated carbon as the control material, the initial VOCs concentration was also 500 ppb. After 24 hours of treatment, the VOCs concentration dropped to 300 ppb, and the removal rate was 40%.

[0068] Comparative Example 2: Commercially available photocatalysts were used to remove VOCs. The initial concentration was 500 ppb. After 24 hours of treatment, the VOCs concentration dropped to 200 ppb, and the removal rate was 60%.

[0069] Table 1 Summary of experimental data

[0070]

[0071] Through the experimental data of the above embodiments and comparative examples, it can be seen that the carbon quantum dot VOCs removal material derived from citrus fruit peels exhibits excellent removal effect in indoor VOCs purification, which is significantly better than traditional activated carbon and commercially available photocatalysts. This shows that the material of the present invention has good application prospects and can effectively improve indoor air quality.

[0072] Example 4

[0073] Select carbon quantum dots with a size greater than 5 nm or less than 3 nm; prepare the carbon quantum dot VOCs removal material in the manner of Example 1, but do not perform multi-stage screening treatment on the carbon quantum dots;

[0074] The VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 24 hours of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0075] Example 5

[0076] Multi-stage screening of calcined and acid-washed citrus peel-derived carbon quantum dots for VOC removal

[0077] S41: collecting the carbon quantum dot powder obtained after completing step S4;

[0078] S42: screening the collected powder through a series of sieves with different apertures, the apertures of the sieves decreasing in sequence, for example, a 200-mesh sieve may be used;

[0079] S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size;

[0080] S44: Repeat step S43 until the powder passes through the finest sieve to obtain carbon quantum dot powder of uniform size;

[0081] S45: Dry the sieved powder to remove surface moisture and ensure the stability and dispersibility of the powder.

[0082] Carbon quantum dots with a size of 3 nm were screened out, and a VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 20 hours of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0083] Example 6

[0084] Multi-stage screening of calcined and acid-washed citrus peel-derived carbon quantum dots for VOC removal

[0085] S41: collecting the carbon quantum dot powder obtained after completing step S4;

[0086] S42: screening the collected powder through a series of sieves with different apertures, the apertures of the sieves decreasing in sequence, for example, a 200-mesh sieve may be used;

[0087] S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size;

[0088] S44: Repeat step S43 until the powder passes through the finest sieve to obtain carbon quantum dot powder of uniform size;

[0089] S45: Dry the sieved powder to remove surface moisture and ensure the stability and dispersibility of the powder.

[0090] Carbon quantum dots with a size of 4 nm were screened out, and a VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 20.5 h of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0091] Example 7

[0092] Multi-stage screening of calcined and acid-washed carbon quantum dot VOCs removal materials

[0093] S41: collecting the carbon quantum dot powder obtained after completing step S4;

[0094] S42: screening the collected powder through a series of sieves with different apertures, the apertures of the sieves decreasing in sequence, for example, a 200-mesh sieve may be used;

[0095] S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size;

[0096] S44: Repeat step S43 until the powder passes through the finest sieve to obtain carbon quantum dot powder of uniform size;

[0097] S45: Dry the sieved powder to remove surface moisture and ensure the stability and dispersibility of the powder.

[0098] Carbon quantum dots with a size of 5 nm were screened out, and a VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 20.5 h of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0099] Table 3 Effect of carbon quantum dot size on catalytic performance

[0100]

[0101]

[0102] Through the experimental data of Examples 4, 5, 6 and 7, it can be seen that when the size of the carbon quantum dot VOCs removal material is between 3nm-5nm, it exhibits excellent removal effect in indoor VOCs purification, which is significantly better than the size of the carbon quantum dot VOCs removal material greater than 5nm or less than 3nm. This shows that when the size of the carbon quantum dots is screened to be between 3nm-5nm, the carbon quantum dots exhibit the best catalytic performance.

[0103] Example 8

[0104] Surface modification of carbon quantum dots

[0105] a: Select polyethyleneimine as the modifier with a concentration of 1g / L.

[0106] b: Dissolve the modifier in deionized water to form a uniform modifier solution.

[0107] c: Add carbon quantum dot powder (100 g) to the modifier solution and stir evenly to ensure full contact.

[0108] d: The mixture was stirred at room temperature for 2 h to promote the chemical reaction between the modifier and the surface of the carbon quantum dots.

[0109] e: After the reaction is completed, the excess modifier is removed by centrifugation and the modified carbon quantum dots are collected.

[0110] f: The modified carbon quantum dots were washed multiple times with deionized water, and finally freeze-dried to obtain dry modified carbon quantum dot powder (80 g).

[0111] Amino (-NH ) groups were introduced by surface modification, and a VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 21 hours of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0112] Example 9

[0113] Surface modification of carbon quantum dots

[0114] a: Select citric acid as the modifier with a concentration of 1g / L.

[0115] b: Dissolve the modifier in deionized water to form a uniform modifier solution.

[0116] c: Add carbon quantum dot powder (100 g) to the modifier solution and stir evenly to ensure full contact.

[0117] d: The mixture was stirred at room temperature for 2 h to promote the chemical reaction between the modifier and the surface of the carbon quantum dots.

[0118] e: After the reaction is completed, the excess modifier is removed by centrifugation and the modified carbon quantum dots are collected.

[0119] f: The modified carbon quantum dots were washed multiple times with deionized water, and finally freeze-dried to obtain dry modified carbon quantum dot powder (80 g).

[0120] Carboxyl (-COOH) groups were introduced through surface modification, and a VOCs removal experiment was carried out in the manner of Example 1. The experimental results showed that after 20 hours of treatment, the VOCs concentration dropped from 500 ppb to 100 ppb.

[0121] Table 4 Effect of surface modification of carbon quantum dots on catalytic efficiency

[0122]

[0123]

[0124] Through the experimental data of the above-mentioned Examples 1, 8 and 9, it can be seen that the surface modification of the carbon quantum dot VOCs removal material shows excellent removal effect in indoor VOCs purification, which is significantly better than the carbon quantum dots without surface modification. This shows that the surface modification of the carbon quantum dots can improve the catalytic performance.

[0125] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A carbon quantum dot VOCs removal material derived from citrus fruit peel, characterized in that: The preparation method of the material comprises the following steps: S1: washing, drying and chopping citrus fruit peels into uniform pieces with a size of 1-5 mm; S2: In a high-purity nitrogen atmosphere, the chopped citrus peel fragments are subjected to programmed temperature calcination at a temperature of 500-800°C, a time of 100-300 min, and a heating rate of 1-15°C / min; S3: Use 0.005-0.1 mol / L dilute hydrochloric acid to pickle the calcined material for 30-60 min to remove impurities; S4: ball milling the pickled material, with a ball milling time of 60-1440 min and a ball milling speed of 200-2000 rpm to obtain a carbon quantum dot VOCs removal material.

2. The preparation method according to claim 1, characterized in that: The method also includes multi-stage screening of the calcined and acid-washed materials to ensure uniform size of the carbon quantum dots, specifically including the following steps: S41: collecting the carbon quantum dot powder obtained after completing step S4; S42: screening the collected powder through a series of sieves with different apertures, wherein the apertures of the sieves decrease in sequence; S43: after each screening, the powder that passes through the current screen is collected, and the powder that does not pass through is returned to the ball mill for further ball milling to further reduce the particle size; S44: Repeat step S43 until the powder passes through the finest sieve to obtain carbon quantum dot powder of uniform size; S45: Drying the sieved powder.

3. The preparation method according to claim 1, characterized in that: The method also includes surface modification of carbon quantum dots to enhance their catalytic activity and selectivity. The specific steps and methods are as follows: a: Select modifiers: Select organic or inorganic compounds containing functional groups such as nitrogen, sulfur, and oxygen; b: Prepare the modifier solution: dissolve the selected modifier in ionized water or ethanol or acetone to form a uniform modifier solution; c: Mixing treatment: Add carbon quantum dot powder into the modifier solution and stir evenly; d: Reaction treatment: Stir the mixture at room temperature to promote the chemical reaction or physical adsorption of the modifier on the surface of the carbon quantum dots; e: Separation and collection: After the reaction is completed, the excess modifier and reaction by-products are removed by centrifugation, filtration or distillation, and the modified carbon quantum dots are collected; f: Washing and drying: The modified carbon quantum dots are washed multiple times with deionized water to remove the residual modifier on the surface, and then dried by freeze drying, spray drying or hot air drying to obtain dry modified carbon quantum dot powder.

4. An indoor VOCs purification system using the carbon quantum dot VOCs removal material derived from citrus fruit peels as claimed in claim 1, characterized in that: The system comprises at least one sensor, a spraying module, an air circulation device and an intelligent control system. The sensor is used to monitor the VOCs concentration in the indoor air in real time. The intelligent control system automatically adjusts the operating speed of the air circulation device according to the monitoring results. The intelligent control system also automatically adjusts the spraying module according to the monitoring results to spray an aqueous solution containing carbon quantum dot powder into the room.

5. A method for removing VOCs using the carbon quantum dot material derived from citrus fruit peels according to claim 1, characterized in that: This includes applying it to the catalytic oxidation of indoor VOCs to reduce the indoor VOCs concentration, and the catalytic oxidation process takes place at room temperature without the need for additional energy input.

6. A method for safety assessment and environmental protection treatment of the carbon quantum dot VOCs removal material derived from citrus fruit peel as claimed in claim 1, characterized in that: This includes evaluating the long-term stability of materials and their potential impact on human health, as well as recycling and harmless treatment of discarded composite materials.

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