CN110562956A - Preparation method and application of ordered mesoporous carbon nanofiber array material - Google Patents

Abstract

The invention relates to a preparation method of an ordered mesoporous carbon nanofiber array material and its application in malachite green electrochemical sensing and analysis. Disclosed is a method for preparing ordered mesoporous carbon nanofiber arrays by using crab shells as carbon sources and calcining in a nitrogen gas atmosphere. The preparation method of the invention is simple, low in energy consumption, and the raw materials are cheap and easy to obtain. This method of using environmental waste to produce functional materials conforms to the country's advocacy of garbage classification and recycling. The prepared ordered mesoporous carbon nanofiber array material was used in the electrochemical sensing analysis of malachite green, realizing the rapid, sensitive and highly selective detection of malachite green.

Description

Preparation method and application of an ordered mesoporous carbon nanofiber array material

technical field

The invention belongs to the technical field of carbon material preparation and electrochemical analysis, and in particular relates to a preparation method of an ordered mesoporous carbon nanofiber array material and its application in a malachite green electrochemical sensor.

Background technique

Malachite green is a cationic triphenylmethane dye, which is widely used in cotton, wool, silk, paper, jute and other industries, because it has antibacterial, bactericidal and antiprotozoal effects, and is also used as a prohibited additive by criminals in fish farming industry, with serious negative impacts on public health and the environment [SACARA A, NAIRI V, SALIS A, et al. Silica-modified electrodes for electrochemical detection of malachite green [J]. Electroanalysis 2017, 29:2602 –2609]. At present, the more common detection methods of malachite green mainly include high-performance liquid chromatography (HPLC), molecularly imprinted microspheres (MIMs) and surface-enhanced Raman (SERS). The traditional instrument method has disadvantages such as complex pre-treatment, high cost of instruments and corresponding supporting equipment, inability to perform simultaneous detection of parallel samples on a large scale, and inability to be used for on-site analysis. Electrochemical sensing analysis has been widely used in practical detection due to the advantages of low cost, simple instrument, fast response and high sensitivity. Unfortunately, conventional electrodes, such as glassy carbon electrodes (GCEs), suffer from large overpotentials and are easily poisoned by products generated during electrochemical processes. Therefore, it is crucial to explore new substrate materials to improve sensitivity and broaden the detection range.

Mesoporous carbon materials have been widely used in many fields due to their good properties. High specific surface area and high porosity make it useful as an adsorbent and gas storage device; controllable pore structure and surface properties and high mechanical stability make it useful as a catalyst carrier, supercapacitor, catalyst; good electrical conductivity and Thermal conductivity, making it useful as a supercapacitor, electrode material, etc. Although there are many successful precedents in the preparation of carbon-based materials, there is still a lack of preparation methods that are simple, quick, low-cost, and recycle environmental waste to produce energy materials. In terms of serious environmental concerns, waste has received extensive attention as a source of carbon materials.

Contents of the invention

The purpose of the present invention is to provide a method for preparing an ordered mesoporous carbon nanofiber array material and its application. The present invention recycles environmental waste to produce functional materials, which has the characteristics of low cost and low energy consumption. The obtained carbon material has super large specific surface area and good electrical conductivity, and can be used as an electrode modification material for malachite green electrochemical sensors. In the detection of malachite green, it has the advantages of high sensitivity and strong selectivity.

A method for preparing an ordered mesoporous carbon nanofiber array material proposed by the present invention, the specific steps are as follows:

(1) The crab shell is calcined in the air at low temperature to remove the organic protein and chitin in the crab shell;

(2) Grinding the product obtained in step (1) into powder in a mortar to obtain crab shell powder;

(3) The crab shell powder obtained in step (2) is combined with a hard template and a surfactant self-assembly method, the crab shell powder is demolded, and then calcined at a high temperature under the protection of nitrogen to obtain an ordered mesopore Carbon nanofiber array materials.

In the present invention, the low-temperature calcination temperature in step (1) is 300°C to 400°C.

In the present invention, the hard template in step (3) is a phenolic resole resin, and the surfactant is a triblock copolymer P123.

In the present invention, the high-temperature calcination temperature in step (3) is 800°C to 1500°C.

The application of the ordered mesoporous carbon nanofiber array material obtained by the preparation method of the invention in the electrochemical sensing and analysis of malachite green. The specific steps are as follows: After grinding the ordered mesoporous carbon nanofiber array material into fine powder, it is uniformly dispersed in a mixed solution composed of water, ethanol and Nafion to obtain a suspension, and the suspension is modified on the surface of a glassy carbon electrode, and the infrared lamp After drying, the differential pulse voltammetry (DPV) was used, the glassy carbon electrode modified by the mesoporous carbon nanofiber array material was used as the working electrode, the platinum wire was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode. Detection of malachite green in ₂ SO ₄ solution.

In the present invention, in the mixed solution composed of water, ethanol and Nafion, water is 800 μL, ethanol is 180 μL, and Nafion is 20 μL.

In the present invention, the carbon material with a pore size larger than 50 nm and presents a fiber array is called a mesoporous carbon nanofiber array. The specific surface of the carbon material is 1200 m ² g ^-1 .

In the present invention, the XRD pattern of the prepared material presents characteristic peaks of carbon at the positions of 22.9° and 43.6°.

In the present invention, the detection parameters of differential pulse voltammetry are: amplitude 50 mV, pulse period 0.5 s, rest time 2 s, accumulation time 500 s, start and stop potential 0-+1.0 V.

In the present invention, +0.53 V in the differential pulse voltammogram is a characteristic oxidation peak of malachite green.

In the present invention, the interfering substances added are: Na ⁺ , Mg ²⁺ , Cu ²⁺ , Ca ²⁺ , SO4 ^2- , Cl ^- , NO3 ^- and violet (CV).

The beneficial effect of the invention is that the waste in daily life is recycled, and the carbon material with good conductivity and large specific surface area is prepared by using simple method, low cost and low energy consumption. The prepared material was successfully applied to the electrochemical sensing of malachite green.

Description of drawings

Figure 1 is the SEM (A, B) and TEM images (C, D) of the mesoporous carbon nanofiber array.

Figure 2 is the BET (A) and XRD pattern (B) of the mesoporous carbon nanofiber array.

Figure 3 is the DPV diagram (A) and linear diagram (B) of detecting malachite green with the mesoporous carbon nanofiber array material as a modified electrode. The figure (A) shows the DPV curves corresponding to 0.1μM, 0.45μM, 0.7μM, 1.2μM, 1.7μM, 2.2μM, 4.68μM, 7.16μM, 12.13μM, and 22.07μM malachite green from bottom to top.

Figure 4 is the anti-interference diagram of the mesoporous carbon nanofiber array material used as a modified electrode to detect malachite green.

Fig. 5 is a flowchart of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with examples, but the present invention is not therefore limited within the scope of the examples.

The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified. The reaction starting materials used in the following examples of the present invention are commercially available analytically pure potassium chloride, potassium ferricyanide, potassium ferrocyanide, malachite green, violet and the like. The electrolyte in the performance test is a 0.05 MH ₂ SO ₄ solution, and the experiments are all carried out at normal temperature.

In the following examples, Japanese Rigaku JSM-6390 scanning electron microscope (SEM) and JEOL2011 transmission electron microscope (TEM) were used with an electron beam acceleration voltage of 200 kV to observe the morphology of the prepared mesoporous carbon nanofiber array material. Bruker D8 X-ray diffractometer (XRD) (Cu K ray) from Germany was used to test XRD, and Micromeritics Tristar3000 analyzer from the United States to test BET. The performance test uses Shanghai Chenhua CHI630E electrochemical workstation to conduct DPV tests at different concentrations of malachite green.

Example 1

Preparation of materials: First, the collected crab shells were calcined in air at 350°C to remove organic protein and chitin, and then ground into powder in a mortar. Using the combination of hard template and surfactant self-assembly method, the calcined crab shell powder was impregnated in the ethanol solution of hot sol and triblock copolymer P123. The impregnated composites were evaporated at 25°C for 6 h, and then further thermally cured at 100°C for 24 h to obtain calcium carbonate/solsol/P123 composites. The obtained complex was pyrolyzed for 2 h at 350 °C under a nitrogen atmosphere at a heating rate of 1 °C min ^-1 to remove the P123 template. Then the composite material was pyrolyzed for 2 h under nitrogen atmosphere at 900 °C with a heating rate of 5 °C min ^-1 for further carbonization. Finally, the obtained calcium carbonate/carbon composite was treated with (6 M) hydrochloric acid solution as the calcium carbonate template. After washing with ultrapure water and ethanol and drying in air at 80 °C for 24 h, the mesoporous carbon nanofiber array material was obtained.

Structural characterization: The carbon material was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM) (see Figure 1). The material is a hole-like fiber array. The material was further characterized by X-ray diffraction (XRD) and specific surface analyzer (BET) (see Figure 2). The material has characteristic peaks of carbon in the XRD diagram, the specific surface area in the BET diagram is 1200 m ² g ^-1 , and the pore diameter is greater than 50 nm.

Electrochemical sensing of malachite green: The prepared mesoporous carbon nanofiber array material was used for electrochemical detection of malachite green. The specific experimental steps are as follows:

Accurately weigh 2 mg of the prepared carbon material with an analytical balance, add 1 mL of water-ethanol Nafion solution, ultrasonically oscillate for 2 h to disperse the material evenly, and then use a 2.5 mL pipette to take 10 µL and apply it on the polished glassy carbon electrode Dry the surface with an infrared lamp and set aside. Malachite green detection uses differential pulse voltammetry (DPV), a three-electrode system consisting of a working electrode (material-modified glassy carbon electrode), a counter electrode (platinum wire) and a reference electrode (saturated calomel). Take ₂₀ mL of 0.05 _MH2SO4 solution, add different concentrations of malachite green, and put it into the electrolytic cell with a stirrer. Set the electrochemical DPV detection parameters: amplitude 50 mV, pulse period 0.5 s, rest time 2 s, accumulation time 500 s, start potential 0 V, end potential +1.0 V. Measure the current response values of 0.1 µM, 0.2 µM, 0.45 µM, 0.70 µM, 1.2 µM, 1.70 µM, 2.20 µM, 4.68 µM, 7.16 µM, 12.13 µM, and 17.10 µM in sequence to obtain the working curve (see Figure 3 working curve from the bottom and above).

The selectivity of the electrochemical sensor of malachite green: the material in the present invention has specificity to detect malachite green, and selectivity is strong. The specific operation steps are as follows:

In the above DPV detection step, choose 5 µM malachite green for interference experiment. Measure the DPV current intensity of 5 µM malachite green without interfering substances, add 2500 μM Na ⁺ , Mg ²⁺ , Cu ²⁺ , Ca ²⁺ , SO ₄ ^2- , The DPV current intensity was measured at 5000 μM Cl ^- and NO ₃ ^- and 250 μM Violet (CV), as shown in Figure 4, the sensor has good specificity in the presence of common ions and other dyes in these waters.

Claims (7)

1. A preparation method of an ordered mesoporous carbon nanofiber array material is characterized by comprising the following specific steps:

(1) Calcining the crab shell in the air at a low temperature to remove organic protein and chitin in the crab shell;

(2) grinding the product obtained in the step (1) into powder in a mortar to obtain crab shell powder;

(3) And (3) demolding the crab shell powder obtained in the step (2) by adopting a method of self-assembling a hard template and a surfactant, and then calcining at high temperature under the protection of nitrogen to obtain the ordered mesoporous carbon nanofiber array material.

2. The production method according to claim 1, characterized in that the low-temperature calcination temperature in step (1) is 300 ℃ to 400 ℃.

3. The method according to claim 1, wherein the hard template in the step (3) is a resol and the surfactant is a triblock copolymer P123.

4. The production method according to claim 1, wherein the high-temperature calcination temperature in the step (3) is 800 ℃ to 1500 ℃.

5. The application of the ordered mesoporous carbon nanofiber array material prepared by the preparation method of claim 1 in the aspect of electrochemical sensing analysis of malachite green.

6. The application according to claim 5, characterized by the specific steps of: grinding ordered mesoporous carbon nanofiber array materials into fine powder, uniformly dispersing the fine powder in a mixed solution consisting of water, ethanol and Nafion to obtain a suspension, modifying the surface of a glassy carbon electrode with the suspension, baking the suspension by using an infrared lamp, and then adopting a Differential Pulse Voltammetry (DPV) method to use the glassy carbon electrode modified by the mesoporous carbon nanofiber array materials as a working electrode, a platinum wire as a counter electrode and a saturated calomel electrode as a reference electrode, and performing MH at 0.05 MH₂SO₄Malachite green was detected in solution.

7. The use according to claim 6, wherein the mixed solution of water, ethanol and Nafion comprises 800. mu.L of water, 180. mu.L of ethanol and 20. mu.L of Nafion.