阅读说明：本技术 纳米氮化碳/氧化铜复合材料、纳米氮化碳/氧化铜复合固相微萃取器及其制备方法和应用 (Nano carbon nitride/copper oxide composite material, nano carbon nitride/copper oxide composite solid phase micro-extractor and preparation method and application thereof ) 是由 卢明华 杨艺欣 王友梅 朱金花 周倩 于 2019-08-27 设计创作，主要内容包括：本发明的目的在于提供一种纳米氮化碳/氧化铜复合材料、纳米氮化碳/氧化铜复合固相微萃取器及其制备方法和应用,所述纳米氮化碳/氧化铜复合材料,由纳米氮化碳分散于去离子水中,在搅拌的同时加入硝酸铜溶液,再逐滴加入六亚甲基四胺溶液,继续搅拌至混合均匀后,停止搅拌,在80-100℃下恒温反应3-5 h,反应结束后,收集沉淀并经洗涤干燥后即得纳米氮化碳/氧化铜复合材料,然后将所述纳米氮化碳/氧化铜复合材料通过二氧化硅胶体包裹在石英纤维表面制成固相微萃取器；本发明所述纳米氮化碳/氧化铜复合材料对多环芳烃具有较好的吸附性能,由该复合材料制备得到的固相微萃取器对多环芳烃的萃取效率高,能够满足多环芳烃的检测需要。(The invention aims to provide a nano carbon nitride/copper oxide composite material, a nano carbon nitride/copper oxide composite solid-phase micro-extractor and a preparation method and application thereof, wherein the nano carbon nitride/copper oxide composite material is prepared by dispersing nano carbon nitride in deionized water, adding a copper nitrate solution while stirring, dropwise adding a hexamethylenetetramine solution, continuously stirring until the mixture is uniformly mixed, stopping stirring, carrying out a constant-temperature reaction at 80-100 ℃ for 3-5 hours, collecting a precipitate after the reaction is finished, washing and drying to obtain the nano carbon nitride/copper oxide composite material, and then wrapping the nano carbon nitride/copper oxide composite material on the surface of quartz fibers through a silicon dioxide colloid to prepare the solid-phase micro-extractor; the carbon nitride/copper oxide composite material has good adsorption performance on polycyclic aromatic hydrocarbons, and a solid phase micro-extractor prepared from the composite material has high extraction efficiency on polycyclic aromatic hydrocarbons, and can meet the detection requirement of polycyclic aromatic hydrocarbons.)

1. the carbon nitride/copper oxide composite material is characterized in that in the carbon nitride/copper oxide composite material, the mass ratio of carbon nitride to copper oxide is 10-40%, and the carbon nitride/copper oxide composite material is prepared by the following method:

(1) Firstly, putting carbon nitride in alkali liquor, stirring for 2-3h at 60-80 ℃, then separating and washing to be neutral, and drying to obtain nano carbon nitride;

wherein the alkali liquor is NaOH solution with the concentration of 6M-8M;

(2) Dispersing the nano carbon nitride obtained in the step (1) in deionized water, adding a copper nitrate solution while stirring, then dropwise adding a hexamethylenetetramine solution, continuously stirring until the mixture is uniformly mixed, stopping stirring, reacting at a constant temperature of 80-100 ℃ for 3-5 hours, collecting precipitates after the reaction is finished, and washing and drying the precipitates to obtain a nano carbon nitride/copper oxide composite material;

Determining the mass of copper oxide according to the required nano carbon nitride/copper oxide composite material, then determining the addition of the nano carbon nitride during the preparation in the step (2) according to the mass of the copper oxide, and simultaneously determining the addition of the copper nitrate according to the molar ratio of the copper oxide to the copper nitrate of 1: 1;

The molar ratio of the added copper nitrate to the added hexamethylenetetramine is 1: 45-1: 60.

2. the method for preparing the solid phase micro extractor by using the nano carbon nitride/copper oxide composite material as claimed in claim 1, which is characterized by comprising the following steps:

a) Uniformly mixing tetraethyl silicate and ethanol, adding HCl aqueous solution with the pH of 2-3 while stirring, continuously stirring to uniformly mix, performing ultrasonic treatment to obtain clear transparent solution, and sealing and standing for 1-3 h to obtain SiO2 sol;

b) Firstly, immersing quartz fibers into 1-2 mol/L NaOH solution for ultrasonic treatment for 1-2 h to activate the surfaces of the quartz fibers, then, ultrasonically treating the quartz fibers by using 0.05-0.2 mol/L HCl solution to neutralize residual NaOH on the quartz fibers, finally, ultrasonically cleaning the quartz fibers for multiple times by using ultrapure water until the quartz fibers are neutral, and drying the quartz fibers for later use;

c) soaking the quartz fiber treated in the step b) into the SiO2 sol obtained in the step a), then inserting the quartz fiber into the carbon nitride/copper oxide composite material, and repeating the steps for a plurality of times to obtain the carbon nitride/copper oxide composite solid-phase micro-extractor.

3. The nano carbon nitride/copper oxide composite solid phase micro-extractor prepared by the method of claim 2.

4. The application of the carbon nitride/copper oxide composite solid-phase micro-extractor of claim 3 in polycyclic aromatic hydrocarbon detection.

5. the application of the carbon nitride/copper oxide composite solid-phase micro-extractor in polycyclic aromatic hydrocarbon detection according to claim 4, is characterized by comprising the following steps:

(i) drawing a standard curve: preparing a plurality of polycyclic aromatic hydrocarbon standard substances into a series of standard solutions with concentration gradients respectively, carrying out gas chromatography detection, and carrying out regression analysis on the concentrations of the standard solutions by using peak areas corresponding to the standard solutions to obtain standard curves of the concentrations of the standard solutions of the polycyclic aromatic hydrocarbons and the peak areas of the standard solutions respectively;

(ii) sample pretreatment: the sample to be detected comprises a soil sample and a solution sample, and the pretreatment process of the soil sample comprises the following steps: dispersing a soil sample in acetone, carrying out centrifugal treatment, collecting supernatant, filtering the supernatant to obtain filtrate, drying, and dissolving the residual solid in the acetone again to obtain an extract liquid; the pretreatment process of the solution sample comprises the following steps: filtering the solution sample to obtain an extract liquid;

(iii) Gas chromatography detection: and (3) placing the nano carbon nitride/copper oxide composite solid phase micro-extractor in the extract liquid obtained in the step (ii), extracting for 15-45 min at 20-60 ℃, then taking out the nano carbon nitride/copper oxide composite solid phase micro-extractor, inserting the nano carbon nitride/copper oxide composite solid phase micro-extractor into a gas chromatography vaporization chamber for thermal desorption, performing gas chromatography detection under the same chromatographic conditions as those in the step (i), measuring the peak area, calculating by combining with the standard curve obtained in the step (i) to obtain the concentration of the polycyclic aromatic hydrocarbon in the test liquid, and further calculating to obtain the concentration of the polycyclic aromatic hydrocarbon in the sample.

6. The application of the carbon nitride/copper oxide composite solid-phase micro-extractor in polycyclic aromatic hydrocarbon detection according to claim 5, wherein the chromatographic conditions are as follows: chromatographic column HP-5; a FID detector; carrier gas: high purity nitrogen; gas flow rate: 1 mL/min; and (3) sample introduction mode: no shunt sampling; sample inlet temperature: 250 ℃ and 290 ℃; detector temperature: 290 ℃ and 300 ℃; column temperature program: the initial temperature is 30-50 ℃, the temperature is kept for 1-3 min, the temperature is increased to 220 ℃ at the speed of 30-50 ℃/min, the temperature is kept for 2-3 min, the temperature is increased to 290 ℃ at the speed of 20-40 ℃/min, and the temperature is kept for 3-5 min.

7. the application of the carbon nitride/copper oxide composite solid-phase micro-extractor in polycyclic aromatic hydrocarbon detection according to claim 5, wherein the polycyclic aromatic hydrocarbon comprises naphthalene, acenaphthene, fluorene, phenanthrene, anthracene and pyrene.

Technical Field

The invention belongs to the technical field of polycyclic aromatic hydrocarbon detection, and particularly relates to a nano carbon nitride/copper oxide composite material, a nano carbon nitride/copper oxide composite solid-phase micro-extractor, and a preparation method and application thereof.

Background

polycyclic Aromatic Hydrocarbons (PAHs) are volatile hydrocarbons produced when substances such as coal, petroleum, wood, tobacco, organic polymers and the like are incompletely combusted, and are widely present in human living environments such as atmosphere, water, soil and crops. PAHs are used as important environmental and food pollutants, more than 200 PAHs are found so far, and recent research shows that polycyclic aromatic hydrocarbon has nondegradable property and potential carcinogenicity. Therefore, the method has important significance for developing a simple, convenient, rapid and sensitive detection method for complex samples such as soil.

Copper oxide, as a P-type semiconductor material with a narrow band gap, has the characteristics of high thermal stability, good chemical stability and the like, and is widely applied to sensors and photocatalysis. However, the poor dispersibility of copper oxide, the small specific surface area and the easy polymerization directly affect the effectiveness of copper oxide. In recent years, a novel non-metallic material, carbon nitride, has attracted much attention because of its simple preparation method, good dispersibility, large specific surface area, good biocompatibility and non-toxicity. However, bulk carbon nitride (b-g-C3N 4) has significant agglomeration phenomena through thermal polymerization of organic molecules, severely affecting its performance. In order to obtain nano carbon nitride (nano-g-C3N 4), some pretreatment is usually required, including ultrasonic separation in different solvents, protonation of acid solution, secondary calcination and multi-step calcination heat treatment. The nano carbon nitride/copper oxide composite material is prepared by heating nano carbon nitride and copper nitrate in water bath, and the composite has unique electrical, optical and chemical characteristics due to small crystal grain size and large specific surface area. In recent years, the application range of the method is wider and wider, but the method has less reports on sample pretreatment.

Disclosure of Invention

The invention aims to provide a nano carbon nitride/copper oxide composite material, a nano carbon nitride/copper oxide composite solid-phase micro-extractor, a preparation method and application thereof.

the invention adopts the following technical scheme:

The carbon nitride/copper oxide composite material comprises a carbon nitride/copper oxide composite material and a copper oxide composite material, wherein the mass ratio of the carbon nitride to the copper oxide composite material is 1: 10-1: 40; according to the invention, the nano carbon nitride/copper oxide compound with different mass ratios can be prepared by changing the mass of the added nano carbon nitride, and the preferable mass ratio of the nano carbon nitride to the copper oxide is 1:20-1:30 in consideration of the adsorption effect and the repeated use times of the composite material, and the nano carbon nitride/copper oxide compound is prepared by adopting the following method:

(1) Firstly, dispersing carbon nitride in alkali liquor, stirring for 2-3h at 60-80 ℃, then separating and washing to be neutral, and drying to obtain nano carbon nitride;

Wherein the alkali liquor is NaOH solution with the concentration of 6M-8M;

(2) dispersing the nano carbon nitride obtained in the step (1) in deionized water, adding a copper nitrate solution while stirring, dropwise adding a hexamethylenetetramine solution, continuously stirring at the speed of 0.01-0.03mL/s until the nano carbon nitride and the copper nitrate solution are uniformly mixed, stopping stirring, reacting at the constant temperature of 80-100 ℃ for 3-5 hours, collecting precipitates after the reaction is finished, and washing and drying to obtain a nano carbon nitride/copper oxide composite material;

Determining the mass of copper oxide according to the required nano carbon nitride/copper oxide composite material, then determining the addition of the nano carbon nitride during the preparation in the step (2) according to the mass of the copper oxide, and simultaneously determining the addition of the copper nitrate according to the molar ratio of the copper oxide to the copper nitrate of 1: 1;

Wherein the molar ratio of the added copper nitrate to the added hexamethylenetetramine is 1: 45-1: 60.

the method for preparing the solid phase micro-extractor by using the nano carbon nitride/copper oxide composite material is characterized by comprising the following steps of:

a) Uniformly mixing tetraethyl silicate and ethanol, adding HCl aqueous solution with the pH of 2-3 while stirring, continuously stirring to uniformly mix, performing ultrasonic treatment to obtain clear transparent solution, and sealing and standing for 1-3 h to obtain SiO2 sol;

b) firstly, immersing quartz fibers into 1-2 mol/L NaOH solution for ultrasonic treatment for 1-2 h to activate the surfaces of the quartz fibers, then, ultrasonically treating the quartz fibers by using 0.05-0.2 mol/L HCl solution to neutralize residual NaOH on the quartz fibers, finally, ultrasonically cleaning the quartz fibers for multiple times by using ultrapure water until the quartz fibers are neutral, and drying the quartz fibers for later use;

c) soaking the quartz fiber treated in the step b) into the SiO2 sol obtained in the step a), then inserting the quartz fiber into the carbon nitride/copper oxide composite material, and repeating the steps for a plurality of times to obtain the carbon nitride/copper oxide composite solid-phase micro-extractor.

the nano carbon nitride/copper oxide composite solid phase micro-extractor prepared by the method is utilized.

The application of the nano carbon nitride/copper oxide composite solid phase micro-extractor in polycyclic aromatic hydrocarbon detection.

The application of the nano carbon nitride/copper oxide composite solid phase micro-extractor in polycyclic aromatic hydrocarbon detection comprises the following steps:

(i) Drawing a standard curve: preparing a plurality of polycyclic aromatic hydrocarbon standard substances into a series of standard solutions with concentration gradients respectively, carrying out gas chromatography detection, and carrying out regression analysis on the concentrations of the standard solutions by using peak areas corresponding to the standard solutions to obtain standard curves of the concentrations of the standard solutions of the polycyclic aromatic hydrocarbons and the peak areas of the standard solutions respectively;

(ii) sample pretreatment: the sample to be detected comprises a soil sample and a solution sample, and the pretreatment process of the soil sample comprises the following steps: dispersing a soil sample in acetone, carrying out centrifugal treatment, collecting supernatant, filtering the supernatant to obtain filtrate, drying, and dissolving the residual solid in the acetone again to obtain an extract liquid; the pretreatment process of the solution sample comprises the following steps: filtering the solution sample to obtain an extract liquid;

(iii) Gas chromatography detection: and (3) placing the nano carbon nitride/copper oxide composite solid phase micro-extractor in the extract liquid obtained in the step (ii), extracting for 15-45 min at 20-60 ℃, then taking out the nano carbon nitride/copper oxide composite solid phase micro-extractor, inserting the nano carbon nitride/copper oxide composite solid phase micro-extractor into a gas chromatography vaporization chamber for thermal desorption, performing gas chromatography detection under the same chromatographic conditions as those in the step (i), measuring the peak area, calculating by combining with the standard curve obtained in the step (i) to obtain the concentration of the polycyclic aromatic hydrocarbon in the test liquid, and further calculating to obtain the concentration of the polycyclic aromatic hydrocarbon in the sample.

further, the chromatographic conditions were as follows: chromatographic column HP-5; a FID detector; carrier gas: high purity nitrogen; gas flow rate: 1 mL/min; and (3) sample introduction mode: no shunt sampling; sample inlet temperature: 250 ℃ and 290 ℃; detector temperature: 290 ℃ and 300 ℃; column temperature program: the initial temperature is 30-50 ℃, the temperature is kept for 1-3 min, the temperature is increased to 220 ℃ at the speed of 30-50 ℃/min, the temperature is kept for 2-3 min, the temperature is increased to 290 ℃ at the speed of 20-40 ℃/min, and the temperature is kept for 3-5 min.

Further, the polycyclic aromatic hydrocarbon includes naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, and pyrene.

the invention has the following beneficial effects:

Among the nanomaterials used as the adsorbent, carbon nitride has good dispersibility, large specific surface area, good high-temperature thermal stability and chemical stability, good biocompatibility and no toxicity, and is widely concerned. In order to further improve the extraction performance of the carbon nitride, the carbon nitride is treated by the alkali solution to obtain the nano carbon nitride, and then the nano carbon nitride/copper oxide composite material is prepared by the nano carbon nitride and the copper oxide by a chemical precipitation method, wherein the composite material has a mesoporous structure, has a larger specific surface area compared with the pure copper oxide, and has higher adsorption efficiency on the polycyclic aromatic hydrocarbon.

In order to facilitate the extraction of polycyclic aromatic hydrocarbon in a sample, the obtained nano carbon nitride/copper oxide composite material is further prepared into a solid phase micro-extractor, compared with solid phase extraction and liquid-liquid extraction, the technology is a novel extraction and separation technology integrating sampling, extraction, concentration and sample introduction, has the advantages of no need of an extraction solvent, small sample amount, short operation time, good reproducibility and the like, and is suitable for analyzing volatility and non-volatility substances. The solid phase micro-extractor prepared by the invention is easy to prepare, low in cost, high in extraction efficiency and excellent in thermal stability, and the test solution obtained after extraction is subjected to gas chromatography detection, wherein the linear range of detection is 0.1-1000 ng/mL, and the detection limit is 0.025 ng/mL.

In addition, the adsorption performance of various materials is compared (as shown in figure 5), and the result shows that the solid phase micro-extractor prepared by the invention has better adsorption and extraction effects on polycyclic aromatic hydrocarbon substances. In addition, in view of the excellent adsorption performance of the solid phase micro-extractor on polycyclic aromatic hydrocarbon and the good stability in the extraction process, the solid phase micro-extractor is expected to be further applied to separation and enrichment of trace compounds in complex matrixes such as environment, biological samples and the like.

Drawings

FIG. 1 is a scanning electron micrograph. (a) Nano carbon nitride; (b) copper oxide; (c) a nano carbon nitride/copper oxide-30 composite (noted as CN/CuO-30); (d) mapping graphs of CN/CuO-30 and C, N, Cu elements; (e) and (f) are side partial views of CN/CuO-30 coatings;

FIG. 2 is an infrared spectrum of copper oxide, nano carbon nitride and the nano carbon nitride/copper oxide composite material prepared in example 1;

FIG. 3 is a thermogram of copper oxide, nano-carbon nitride and nano-carbon nitride/copper oxide composite material prepared in example 1;

FIG. 4 is a graph showing the adsorption and desorption curves of N2 for copper oxide (a) and the carbon nitride/copper oxide composite material (b) prepared in example 1;

FIG. 5 is a graph comparing the adsorption performance of the carbon nitride/copper oxide nanocomposite prepared in example 1 on different polycyclic aromatic hydrocarbons;

FIG. 6 is a standard graph of six polycyclic aromatic hydrocarbons, (a) naphthalene; (b) acenaphthene; (c) fluorene; (d) phenanthrene; (e) anthracene; (f) pyrene;

FIG. 7 is a gas chromatogram for detecting polycyclic aromatic hydrocarbons in a water sample in example 2, wherein the addition of a standard solution of 100ng/mL is indicated; (1) naphthalene (NAP); (2) acenaphthene (ANE); (3) fluorene (FLU); (4) phenanthrene (PHE); (5) anthracene (ANT); (6) pyrene (PYR);

FIG. 8 is a gas chromatogram for testing polycyclic aromatic hydrocarbons in the open-ended suburb soil in example 3, wherein the standard addition indicates that 100ng/mL of standard solution is added into the soil 1; (1) naphthalene; (2) acenaphthene; (3) fluorene; (4) phenanthrene; (5) anthracene; (6) pyrene;

FIG. 9 is a gas chromatogram for detecting polycyclic aromatic hydrocarbons in soil near a commercial chemical plant in example 4, wherein the standard solution is 100ng/mL in soil 2; (1) naphthalene; (2) acenaphthene; (3) fluorene; (4) phenanthrene; (5) anthracene; (6) pyrene.

Detailed Description

In order to make the technical purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific embodiments.