阅读说明：本技术 一种巴旦木壳基氮掺杂纳米多孔碳材料的制备方法及应用 (preparation method and application of badam shell-based nitrogen-doped nano porous carbon material ) 是由 夏木西卡玛尔·买买提 伊力亚丝·*** 胡广志 乔孟飞 于 2019-09-05 设计创作，主要内容包括：本发明涉及一种巴旦木壳基氮掺杂纳米多孔碳材料的制备方法和应用。该方法以巴旦木壳为碳源,先在温度450℃、N<Sub>2</Sub>下直接碳化5小时,所得到的碳材料浸泡于KOH溶液后,温度80℃下烘干,在600℃、N<Sub>2</Sub>下活化2小时,再以尿素为氮源,采用水热法在活化所制备的纳米多孔碳上掺杂氮原子。通过该方法获得的氮掺杂纳米多孔碳材料应用于自来水中的Pb<Sup>2+</Sup>的电化学检测,具有灵敏度高、检出限低、重复性和稳定性好、抗干扰能力强等特点,是一种应用于制备电化学传感器件的理想材料,为解决自来水中Pb<Sup>2+</Sup>的检测提供了一个新的途径。(the invention relates to a preparation method and application of a badam shell based nitrogen-doped nano porous carbon material. According to the method, a buckskin wood shell is taken as a carbon source, the carbon is directly carbonized for 5 hours at the temperature of 450 ℃ and N2, the obtained carbon material is soaked in a KOH solution, dried at the temperature of 80 ℃, activated for 2 hours at the temperature of 600 ℃ and N2, and then urea is taken as a nitrogen source, and a hydrothermal method is adopted to dope nitrogen atoms on the activated nano porous carbon. The nitrogen-doped nano porous carbon material obtained by the method is applied to electrochemical detection of Pb2+ in tap water, has the characteristics of high sensitivity, low detection limit, good repeatability and stability, strong anti-interference capability and the like, is an ideal material for preparing an electrochemical sensing device, and provides a new way for solving the detection of Pb2+ in tap water.)

1. A preparation method of a badam shell-based nitrogen-doped nano porous carbon material is characterized by comprising the following steps:

a. cleaning 8g of badam shell, drying at 80 ℃ for 3 hours, and grinding into powder;

b. b, heating the powder obtained in the step a to 450 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere of a tubular furnace, preserving heat for 5 hours, and naturally cooling to room temperature;

c. taking 1g of the material prepared in the step b, mixing deionized water and KOH according to the mass ratio of 1:1, performing ultrasonic treatment for 10 minutes to uniformly disperse the mixture, stirring the mixture for 4 hours at the temperature of 80 ℃, and standing the mixture for 20 hours;

d. C, filtering the mixture obtained in the step c, drying at the temperature of 80 ℃, heating to 600-800 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere of a tubular furnace, preserving heat for 2 hours, and naturally cooling to room temperature;

e. And d, taking 50mg of the material obtained in the step d, adding 250mg of urea into a mixed solution of water and ethanol with the volume ratio of 1:1, mixing, performing ultrasonic treatment for 30 minutes to uniformly disperse the urea, putting the mixed solution into a high-pressure reaction kettle, reacting at the temperature of 180 ℃ for 12 hours, filtering, and drying at the temperature of 80 ℃ for 4 hours to obtain the almond shell based nitrogen-doped nano porous carbon material.

2. Use of the badam shell-based nitrogen-doped nano-porous carbon material obtained by the method according to claim 1 as an electrode modifier in preparation of electrochemical sensing for detecting Pb2 +.

Technical Field

The invention relates to a preparation method and application of a badam shell based nitrogen-doped nano porous carbon material. In particular to direct carbonization and chemical activation of a badam shell, nitrogen atoms doping on the obtained carbon material by using a hydrothermal method and application thereof in the research of electrochemical detection of heavy metal sensors.

background

Heavy metal elements such as cobalt, copper, manganese, iron, zinc, etc. play an important role in the body, and these trace metal elements are necessary for the normal progress of metabolic activities of the body. However, the toxic heavy metal elements such as lead, cadmium, mercury, arsenic, antimony, etc., in very small amounts, cause serious environmental problems and serious diseases of the central nervous system, liver, kidney, skin and bone by accumulating in the human body. At present, heavy metal pollution is one of the most serious environmental pollution problems facing countries in the world today. In China, with the rapid development of industrial and agricultural production and the acceleration of urbanization process, various industrial and mining industries, the disordered and excessive discharge of domestic wastewater and wastes, and the heavy metal pollution of different degrees on the soil, air and water environments in rural areas and surrounding areas of cities. Because the highly toxic heavy metal pollution has the characteristics of irreversible conversion, long-term property, accumulation, latency and the like, once the ecological system is polluted, the comprehensive treatment cost is difficult to estimate. In the prevention and treatment of heavy metal pollution, the prevention is more important than the treatment, and the on-site, rapid and accurate detection of the heavy metal content is a precondition for the prevention work. Therefore, it is necessary and urgent to establish and develop an efficient, rapid and sensitive technology for detecting heavy metal pollutants.

currently, the heavy metal detection methods mainly include atomic absorption spectroscopy and emission spectroscopy based on spectroscopic techniques, and analysis methods that utilize atomic (or ion) absorption or emission specific spectroscopy to measure the content of elements. The methods have the advantages of high sensitivity, strong anti-interference capability, high analysis speed, good selectivity and the like, so the methods gradually become one of the standard methods for detecting the content of the heavy metal from the middle of the last century. And the spectrophotometry and the fluorescence spectroscopy which have relatively low cost and are based on the molecular spectroscopy technology utilize the heavy metal ions and the compound to be combined to absorb or emit light with specific wavelength to carry out measurement, have the characteristics of simple instrument, wide application range, reliability and the like, and start to be popularized. In addition to the above-mentioned methods, detection methods such as biochemical analysis, mass spectrometry, and high performance liquid chromatography are available.

Although the detection methods have the advantages, the detection methods have disadvantages, such as expensive required instruments, complex sample pretreatment, high operation cost, long detection time and the like, so that the actual requirements of modern environmental protection on real-time, rapid and on-site in-situ detection are difficult to meet. Compared with the traditional instrument analysis technologies, the electrochemical heavy metal detection method has the advantages of low cost, high sensitivity, good accuracy and selectivity, capability of performing on-site real-time and on-line detection and the like, and is beginning to attract the attention of researchers.

Among the various methods used for electrochemical detection, Anodic Stripping Voltammetry (ASV) is one of the most effective methods that is considered to have the highest sensitivity. In the anodic stripping voltammetry, the characteristics of the specific surface area, structure, adsorbability, catalytic activity and the like of the material used for modifying the surface of the working electrode directly influence the performances of sensitivity, selectivity, stability and the like. So far, materials such as graphene, carbon nanotubes, metal oxide nanoparticles, metal/carbon nanocomposites and the like are used as electrode surface modifiers due to the advantages of large specific surface area, good chemical stability, good conductivity and the like, and achieve satisfactory results in the field of electrochemical detection of heavy metals. Meanwhile, the novel material has the problems of expensive raw materials, complex preparation process, difficulty in large-scale production and the like.

at present, in view of the sustainable development of resources and the need of environmental protection, people pay more and more attention to the preparation of porous carbon from renewable biological waste and the application research of the porous carbon in environmental adsorbents and capacitor electrode materials. At present, researches on preparation of porous carbon by using biomass wastes such as hair, coffee residues, cattle, fruit peels, bagasse, egg shells, egg shell membranes, peanut shells, agaric, cigarette filters and the like as precursors are reported frequently. The development and utilization of biomass waste are environment-friendly, and meet the green and sustainable development strategy of urgent need. The porous carbon material prepared by taking the biomass waste as the raw material is mainly used for the research on catalyst carriers, environmental adsorbents and capacitor electrode materials, but is rarely reported in the field of electrochemical detection of heavy metals or other small molecules.

The invention discloses a method for preparing a nano porous carbon material with good electrochemical performance by using a nut-almond shell planted in south China as a carbon source.

Disclosure of Invention

the invention aims to provide a preparation method and application of a badam shell-based nitrogen-doped nano porous carbon material. According to the method, a badam shell is taken as a carbon source, firstly, direct carbonization is carried out for 5 hours at the temperature of 450 ℃ and under the condition of N2, the obtained material is soaked in a KOH solution and then activated for 2 hours under the condition of N2, then, urea is taken as a nitrogen source, nitrogen atoms are doped on nano porous carbon by adopting a hydrothermal method, and the badam shell-based nitrogen-doped nano porous carbon material is obtained. The badam shell-based nitrogen-doped nanoporous carbon material obtained by the method is applied to electrochemical detection of Pb2+ in tap water. The prepared material has the characteristics of high sensitivity, low detection limit, good repeatability and stability, strong anti-interference capability and the like, is an ideal material for preparing an electrochemical sensing device, and provides a new way for solving the detection of Pb2+ in tap water.

The preparation method of the badam shell based nitrogen-doped nano porous carbon material comprises the following steps:

a. Cleaning 8g of badam shell, drying at 80 ℃ for 3 hours, and grinding into powder;

b. b, heating the powder obtained in the step a to 450 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere of a tubular furnace, preserving the temperature for 5 hours, and naturally cooling to room temperature;

c. Taking 1g of the material prepared in the step b, mixing deionized water and KOH according to the mass ratio of 1:1, performing ultrasonic treatment for 10 minutes to uniformly disperse the mixture, stirring the mixture for 4 hours at the temperature of 80 ℃, and standing the mixture for 20 hours;

d. C, filtering the mixture obtained in the step c, drying at the temperature of 80 ℃, heating to 600-800 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere of a tubular furnace, preserving heat for 2 hours, and naturally cooling to room temperature;

e. And d, taking 50mg of the material obtained in the step d, adding 250mg of urea into a mixed solution of water and ethanol with the volume ratio of 1:1, mixing, performing ultrasonic treatment for 30 minutes to uniformly disperse the urea, putting the mixed solution into a high-pressure reaction kettle, reacting at the temperature of 180 ℃ for 12 hours, filtering, and drying at the temperature of 80 ℃ for 4 hours to obtain the almond shell based nitrogen-doped nano porous carbon material.

the application of the badam shell-based nitrogen-doped nano-porous carbon material obtained by the method as an electrode modifier in preparation of electrochemical sensing for detecting Pb2 +.

the preparation method and the application of the almond shell based nitrogen-doped nano porous carbon material adopt three steps of direct carbonization of biomass almond shell waste, chemical activation, nitrogen atom doping through hydrothermal reaction and the like. The Badan wood shell-based nitrogen-doped nano porous carbon material obtained by the method is used as an electrode modifier. The adsorbent has adsorbability to Pb2+ in water, and can realize electrochemical detection of Pb2+ with ppb level concentration in tap water. The material has the advantages of good selectivity, reproducibility, accuracy, higher recovery rate, simple preparation process, low cost and the like, and has great application potential in the aspect of electrochemical detection of Pb2+ in tap water.

Drawings

FIG. 1 is a schematic view of the present invention;

FIG. 2 is an SEM representation of the nanoporous carbon material obtained in example 3 of the invention. FIG. 2a shows that the obtained carbon material is honeycomb-shaped, as can be seen from FIG. 2b, the surface of the carbon material has a large number of micropores, and the BET test result shows that the specific surface area reaches 1075m 2/g;

FIG. 3 is an XPS chart of a nanoporous carbon material obtained in example 3 of the present invention before and after nitrogen doping, wherein 3a is an element composition before nitrogen doping; the main elements are carbon (91.05%) and oxygen (8.95%), 3b is an XPS diagram after nitrogen doping, and as can be seen from the diagram, the element components after doping become carbon (89.21%), oxygen (8.56%) and nitrogen (2.23%);

FIG. 4 is an optimization experiment of the electrochemical detection conditions of Pb2+ according to the present invention, wherein 4a is the optimization of the material loading, and the result shows that 7.5 μ g is the optimal loading; 4b is the pH value optimization result of the supporting electrolyte, and as can be seen from the figure, the optimal pH value is 5.0, 4c and 4d are the optimization results of the enrichment potential and time respectively, and the results show that the optimal enrichment potential and time are-1.3V and 300s respectively;

fig. 5 is a graph of electrochemical sensing properties of heavy metal according to the present invention, wherein 5a is an electrochemical response graph of a nitrogen-doped nanoporous carbon modified glassy carbon electrode prepared in example 3, and different concentrations of Pb2+ are detected by DPV, as shown in the graph, the peak intensity of a dissolution peak is continuously increased with the increase of the concentration of Pb2+, and as can be seen from the graph, the detection range of Pb2+ is 2-120 μ g/L, which illustrates that the nitrogen-doped nanoporous carbon material obtained in the present invention has a wider response range to Pb2 +; 5b shows that the peak current has a good linear relation with the concentration of Pb2+ between 2 and 120 mu g/L, the equation is Ip 0.1417CPb2+ -0.0176, R2 is 0.99, and the detection limit is 0.7 mu g/L, and the result shows that the almond shell-based nitrogen-doped nanoporous carbon material has a good application prospect in electrochemical detection of Pb2 +.

Detailed Description

the invention is further illustrated by the following specific examples.