Modified sugarcane activated carbon electrode material, and preparation method and application thereof

Abstract

The application discloses a modified sugarcane activated carbon electrode material and a preparation method and application thereof. The method comprises the following steps: preparing sugarcane activated carbon powder, adding the activated carbon powder into anhydrous ethanol, then adding polytetrafluoroethylene, heating and stirring until a gel is generated, and preparing an activated carbon gel; coating the activated carbon gel on the surface of a nickel foam, drying, pressing by using a tablet press, and then calcining to prepare a sugarcane activated carbon electrode; dissolving Pluronic F127, CoCl3.6H2O and CH3COOH in water, stirring to prepare a solution, then adding the sugarcane activated carbon electrode and 2-amino terephthalic acid, and stirring to perform hydrothermal reaction, and finally preparing a modified sugarcane activated carbon electrode material. The modified sugarcane activated carbon electrode material prepared by the application has high oxygen utilization rate, has high degradation efficiency on pollutants under the condition that aeration is not needed, and solves the problem that energy consumption is high due to an aeration device in an electro-Fenton process.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, specifically relating to a modified sugarcane activated carbon electrode material, its preparation method, and its application. Background Technology

[0002] Electro-Fenton (EF) is an advanced oxidation process. Its principle is mainly based on the Fenton process, that is, the reaction system contains Fe. 2+ When reacting with H₂O₂, it can generate ·OH (oxidation potential of 2.8 V), which has extremely strong oxidizing power and can be used to degrade organic pollutants. The electro-Fenton process overcomes some limitations of the Fenton process, such as the need for external addition of Fe. 2+ Salt and H2O2 are used, but during the electro-Fenton process, H2O2 is generated in situ, thus avoiding the transportation and storage problems of H2O2 in the Fenton process. Furthermore, the Fe... 2+ Similar electroregeneration was performed at the cathode, reducing the initial Fe addition. 2+ The dosage almost eliminated the formation of iron slag.

[0003] Since the electro-Fenton process utilizes oxygen to generate H2O2 in situ at the cathode, its efficiency largely depends on the cathode's performance, as it determines H2O2 production. Furthermore, the low dissolved oxygen concentration in the water necessitates aeration devices, which consume over 95% of the electrical energy. Therefore, low oxygen utilization efficiency and high energy consumption are the biggest obstacles to the practical application of the electro-Fenton process.

[0004] Traditional carbonaceous materials such as carbon fiber, carbon sponge, carbon felt, and reticulated glassy carbon have been widely reported for use in the preparation of electrode materials. For example, reference (Shi Shen et al., Research on the Selection of Electrode Materials for the Electro-Fenton Method of Cathode and its Application in the Treatment of Dyeing and Printing Wastewater, Ordnance Materials Science and Engineering, 2014, 37: 115-117) uses an electro-Fenton reactor with activated carbon fiber cathode material to study various factors affecting the treatment effect of dyeing and printing wastewater. Reference (Chen Ziyu et al., Research on the Degradation of Methyl Orange by Carbon Felt Electrode Electro-Fenton, Applied Chemical Industry, 2020, 49: 143-146) studies the degradation of methyl orange in azo dye wastewater by carbon felt electrode electro-Fenton. Reference (Chen Cong, Research on the Efficiency of Pretreatment of Dyeing and Printing Wastewater by a Novel Nickel Electrode Electro-Fenton Method, Master's Thesis, Harbin Institute of Technology, 2015) uses a graphite plate anode and a foamed nickel electro-Fenton system to treat actual wastewater. However, none of these references have solved the technical problems of low oxygen utilization efficiency and high energy consumption in the electro-Fenton method. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing modified sugarcane activated carbon electrode materials. This method utilizes sugarcane to prepare activated carbon electrodes and constructs a mesh framework on the surface of the activated carbon electrodes that captures oxygen, thereby improving oxygen utilization and achieving an electro-Fenton system that does not require aeration. Experimental results show that it has a good degradation effect on the pollutant propranolol.

[0006] Another object of the present invention is to provide a modified sugarcane activated carbon electrode material prepared by the above method.

[0007] Another object of the present invention is to provide the application of the above-mentioned modified sugarcane activated carbon electrode material.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for preparing a modified sugarcane activated carbon electrode material includes the following steps:

[0010] (1) Fresh sugarcane or sugarcane bagasse after juicing is pretreated, calcined, activated and ground to obtain charcoal powder;

[0011] (2) Add carbon powder to anhydrous ethanol, then add polytetrafluoroethylene, heat and stir until a gel appears, and obtain activated carbon gel.

[0012] (3) The activated carbon gel was coated onto the surface of the nickel foam, dried, pressed by a tablet press, and then calcined to obtain the sugarcane activated carbon electrode;

[0013] (4) Pluronic F127 (block polyether F-127), CoCl3·6H2O (cobalt trichloride hexahydrate) and CH3COOH are dissolved in water and stirred to obtain a mixed solution; sugarcane activated carbon electrode (SC) and NH2-BDC (2-aminoterephthalic acid) are added to the mixed solution and stirred for a period of time to carry out a hydrothermal reaction to obtain modified sugarcane activated carbon electrode material (abbreviated as SC-RF).

[0014] Step (1) includes the following steps: peeling and cutting the sugarcane into sections and drying it, or drying the sugarcane pomace after juicing, then ultrasonically cleaning it with water and ethanol to remove residual substances, and drying it thoroughly; then calcining and carbonizing the dried sugarcane at 800~1000 ℃ for 5 h under inert gas protection; then activating the carbonized sugarcane at 700~800 ℃ for 10 h in a CO2 atmosphere, and grinding the activated sugarcane into carbon powder. Experiments showed that the electrode prepared by carbonization at 900 ℃ in a nitrogen atmosphere and then activation at 750 ℃ ​​in a CO2 atmosphere had the best performance.

[0015] The average adsorption pore size of the carbon powder is 2.05 nm.

[0016] The heating temperature in step (2) is 80 ℃.

[0017] In step (2), the mass ratio of carbon powder to polytetrafluoroethylene is 8:1, and the volume ratio of anhydrous ethanol to polytetrafluoroethylene is 20:2.

[0018] The drying temperature in step (3) is 60 °C; the calcination refers to calcination at 360 °C for 1 h under inert gas protection.

[0019] The loading of the nickel foam surface activated carbon in step (3) is 0.05 g / cm³. 2 .

[0020] The size of the nickel foam mentioned in step (3) is 2 cm × 2 cm.

[0021] The pressure of the tablet press in step (3) is 4 MPa.

[0022] In step (4), the amounts of Pluronic F127, CoCl3·6H2O, CH3COOH and NH2-BDC are 360 ​​parts by mass, 400 parts by mass, 0.6 parts by volume and 136 parts by mass, respectively. In this invention, 1 part by mass: 1 part by volume = 1 mg / mL.

[0023] The hydrothermal reaction mentioned in step (4) refers to heating at 110 °C for 24 h.

[0024] The present invention also provides the application of the modified sugarcane activated carbon electrode material prepared above, which can be used to degrade nonsteroidal drugs (e.g., propranolol) in wastewater.

[0025] The specific steps of the application include: using a ruthenium-iridium electrode as the anode and modified sugarcane activated carbon electrode material (SC-RF) as the cathode, fixing the anode and cathode in a through-flow reactor with a distance of 1 cm between the two electrodes; adding supporting electrolytes Na2SO4 and FeSO4 to the wastewater containing non-steroidal drugs to be degraded, and adjusting the pH to 3 with H2SO4 to obtain a reaction solution; drawing the reaction solution into the through-flow reactor using a peristaltic pump to obtain an electro-Fenton system, and then degrading it by electricity.

[0026] The nonsteroidal drug in the wastewater to be degraded is propranolol, with an initial concentration of 10 mg / L; the stirring speed is 500 rpm.

[0027] Samples were taken during the degradation process to determine the concentration of propranolol and calculate the removal rate of propranolol. The removal rate of propranolol was greater than 90%.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The present invention provides a cathode material prepared by constructing a mesh framework on the surface of a sugarcane activated carbon electrode. The modified sugarcane activated carbon electrode material has a higher O2 capture capacity than the unmodified electrode, thereby generating more H2O2 and hydroxyl radicals, which can improve electrochemical properties and has a good degradation effect on propranolol in pollutants.

[0030] 2. The modified sugarcane activated carbon electrode material prepared by this invention has a higher oxygen utilization rate compared with other activated carbon electrodes, and has a higher degradation efficiency for pollutants without the need for aeration, thus solving the problem of high energy consumption caused by aeration devices in electro-Fenton electrodes. Attached Figure Description

[0031] Figure 1 These are electron microscope images of the unactivated and activated carbon powders prepared in Example 1.

[0032] Figure 2 This is a linear scan voltammetry diagram of the SC electrode and SC-RF electrode material prepared in Example 1.

[0033] Figure 3 The SC electrode and SC-RF electrode materials prepared in Example 1 are used to degrade propranolol.

[0034] Figure 4 This is a comparison diagram of the SC-RF electrode material prepared in Example 1 and the CNTs-RF electrode material prepared in Comparative Example 1 used to degrade propranolol.

[0035] Figure 5 This is a comparison diagram of the SC-RF electrode material prepared in Example 1 and the HMC-RF electrode material prepared in Comparative Example 2 used to degrade propranolol. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0037] Example 1

[0038] This embodiment describes a method for preparing and modifying sugarcane activated carbon electrode materials. The method is as follows:

[0039] (1) Peel the sugarcane and cut it into sections. Dry the sugarcane at 60 °C. Clean the dried sugarcane with deionized water and ethanol using ultrasonic cleaning to remove residual substances. After thorough cleaning, dry the sugarcane again. Calcinate the dried sugarcane at 900 °C for 5 h in a N2 atmosphere. Activate the carbonized sugarcane at 750 °C for 10 h in a CO2 atmosphere. Grind the activated sugarcane into charcoal powder.

[0040] (2) Add the obtained carbon powder to 20 mL of anhydrous ethanol, then add 2 mL of polytetrafluoroethylene, heat in a water bath at 80 °C, and stir until a gel appears to obtain activated carbon gel. The mass ratio of carbon powder to polytetrafluoroethylene is 8:1.

[0041] (3) Cut the nickel foam into 2 cm × 2 cm pieces, clean the cut nickel foam with acetone, sonicate for 20 min, rinse the cleaned nickel foam with deionized water, and dry at 60 ℃ for later use; uniformly coat the obtained activated carbon gel onto the surface of the nickel foam (the activated carbon loading is 0.05 g / cm). 2 The coated nickel foam was placed in an oven at 60 °C and dried overnight. The dried nickel foam was pressed using a tablet press (pressure 4 MPa). The pressed nickel foam was then calcined at 360 °C for 1 h under N2 atmosphere to obtain the SC electrode.

[0042] (4) The obtained SC electrode was immersed in acetone and sonicated for 30 minutes to remove impurities and oil stains, and then thoroughly rinsed with deionized water. Pluronic F127 (360 mg), CoCl3·6H2O (400 mg), and CH3COOH (0.6 mL) were dissolved in 30 mL of deionized water and stirred for 1 hour to obtain a mixed solution. Subsequently, one cleaned SC electrode (2 cm × 2 cm) and 136 mg of NH2-BDC were added to the above mixed solution and stirred for another 2 h. The resulting mixture was sealed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 110 °C for 24 h to obtain an SC-RF electrode. After cooling to room temperature, the SC-RF electrode was washed 5 times with ethanol and dried overnight in a vacuum oven at 80 °C.

[0043] Figure 1 (a) is an SEM image of unactivated sugarcane char powder (sugarcane blocks that were washed and dried in Example 1 were calcined at 900°C and then ground into powder). It can be seen that the surface is smooth and there are regular pores on the surface of the activated carbon. Figure 1 (b) is a SEM image of the activated sugarcane activated carbon powder, which clearly shows that the pore size of the activated powder is larger than that of the unactivated powder. Figure 2 The LSV diagrams are for the SC electrode and the SC-RF electrode.

[0044] The SC electrode and SC-RF electrode prepared in Example 1 were used as cathodes for the degradation of propranolol. Experimental conditions: 200 mL of a 10 mg / L propranolol hydrochloride aqueous solution was measured, and 1.42 g of Na₂SO₄ electrolyte and 0.0278 g of FeSO₄ were added. The pH was adjusted to 3 with 1 mol / L H₂SO₄, and the mixture was poured into an electrolytic cell to prepare the reaction solution. The reaction solution was pumped into a permeation reactor using a peristaltic pump. SC and SC-RF electrodes were used as cathodes, and ruthenium-iridium electrodes of the same size were fixed as anodes in the permeation reactor. A dual-electrode system with a constant current density of 10 mA / cm² was used. 2 Magnetic stirring speed 500 r / min, electrolytic degradation at room temperature for 30 min.

[0045] like Figure 3 As shown, the degradation rates of propranolol by the SC electrode (the sugarcane activated carbon electrode made from activated sugarcane activated carbon powder in Example 1) and the SC-RF electrode (the electrode after constructing a mesh framework on the surface of the SC electrode using a hydrothermal method in Example 1) were 62.9% and 90.1%, respectively, after 30 min. This indicates that the modified electrode is superior to the unmodified electrode, and the modified electrode exhibits a faster degradation rate. This is because the modified electrode more easily captures dissolved oxygen from the water, resulting in a higher H2O2 production at the same time point, and the generation of more hydroxyl radicals, leading to faster degradation of propranolol.

[0046] Comparative Example 1

[0047] This comparative example uses multi-walled carbon nanotubes to replace sugarcane activated carbon to prepare multi-walled carbon nanotube modified electrodes (CNTs-RF). The preparation steps are as follows:

[0048] (1) Add multi-walled carbon nanotube powder to 20 mL of anhydrous ethanol, then add 2 mL of polytetrafluoroethylene and heat in a water bath at 80 °C. Stir until a gel appears to obtain multi-walled carbon nanotube gel. The mass ratio of multi-walled carbon nanotube powder to polytetrafluoroethylene is 8:1.

[0049] (2) Cut the nickel foam into 2 cm × 2 cm pieces, clean the cut nickel foam with acetone, sonicate for 20 min, rinse the cleaned nickel foam with deionized water, and dry at 60 ℃ for later use; uniformly coat the obtained multi-walled carbon nanotube gel onto the surface of the nickel foam (the multi-walled carbon nanotube loading is 0.05 g / cm). 2 The coated nickel foam was placed in an oven at 60 °C and dried overnight. The dried nickel foam was pressed using a tablet press, and the pressed nickel foam was calcined at 360 °C for 1 h under N2 atmosphere to obtain the electrode.

[0050] (3) The obtained electrode was immersed in acetone and sonicated for 30 minutes to remove impurities and oil stains, and then thoroughly rinsed with deionized water. Pluronic F127 (360 mg), CoCl3·6H2O (400 mg), and CH3COOH (0.6 mL) were dissolved in 30 mL of deionized water and stirred for 1 hour. Subsequently, one cleaned electrode (2 cm × 2 cm) and 136 mg of NH2-BDC were added to the above solution and stirred for another 2 h. The resulting mixture was sealed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 110 °C for 24 h to obtain a CNTs-RF electrode. After cooling to room temperature, the CNTs-RF electrode was washed 5 times with ethanol and dried overnight in a vacuum oven at 80 °C.

[0051] Figure 4 The figure shows a comparison of the degradation effects of the SC-RF electrode and the CNTs-RF electrode prepared in Example 1 on propranolol under the same conditions. The degradation experimental conditions were the same as in Example 1. It can be clearly seen from the figure that the degradation effect of the SC-RF electrode is better than that of the CNTs-RF electrode.

[0052] Comparative Example 2

[0053] This comparative example uses sugarcane activated carbon electrodes (HMC-RF) prepared by different processes. The preparation methods are as follows:

[0054] (1) Fresh sugarcane was peeled and cut into sections, then dried at 60 °C. The dried sugarcane sections were ultrasonically cleaned with deionized water and ethanol to remove residual substances, and then dried again. The dried sugarcane was ground into powder, and the sugarcane powder (6.0 g) and ultrapure water (60 mL) were added to a Teflon-lined hydrothermal reactor and stirred for 30 min. The reactor was then placed in an oven and heated at 200 °C for 24 h to hydrolyze the unstable components in the biomass, resulting in hydrogen-carbon (HC) with a widened pore structure.

[0055] (2) After filtration and drying, hydrogen-carbon and zinc chloride activator are mixed at a mass ratio of 1:3. The homogeneous mixture is then heated at 800 °C (heating rate of 5 °C / min). -1 The biochar was calcined in a tube furnace under N2 atmosphere for 1 hour. After cooling, it was washed several times with 1 mol / L HCl solution and ultrapure water to remove residual impurities, and then dried overnight in a vacuum oven at 80 °C to obtain biochar, named HMC.

[0056] (3) Add HMC powder to 20 mL of anhydrous ethanol, then add 2 mL of polytetrafluoroethylene, heat in a water bath at 80°C, and stir until a gel appears to obtain activated carbon gel. The mass ratio of HMC powder to polytetrafluoroethylene is 8:1.

[0057] (4) Cut the nickel foam into 2 cm × 2 cm pieces, clean the cut nickel foam with acetone, sonicate for 20 min, rinse the cleaned nickel foam with deionized water, and dry at 60 ℃ for later use; uniformly coat the obtained activated carbon gel onto the surface of the nickel foam (the activated carbon loading is 0.05 g / cm). 2 The coated nickel foam was placed in an oven at 60 °C and dried overnight. The dried nickel foam was pressed using a tablet press, and the pressed nickel foam was calcined at 360 °C for 1 h under N2 atmosphere to obtain the HMC electrode.

[0058] (5) The obtained HMC electrode was immersed in acetone and sonicated for 30 minutes to remove impurities and oil stains, and then thoroughly rinsed with deionized water. Pluronic F127 (360 mg), CoCl3·6H2O (400 mg), and CH3COOH (0.6 mL) were dissolved in 30 mL of deionized water and stirred for 1 hour. Subsequently, one cleaned electrode (2 cm × 2 cm) and 136 mg of NH2-BDC were added to the above solution and stirred for another 2 h. The resulting mixture was sealed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 110 °C for 24 h to obtain the HMC-RF electrode. After cooling to room temperature, the HMC-RF electrode was washed 5 times with ethanol and dried overnight in a vacuum oven at 80 °C.

[0059] Figure 5 The figure shows a comparison of the degradation effects of the SC-RF electrode and the HMC-RF electrode prepared in Example 1 on propranolol under the same conditions. The degradation experimental conditions were the same as in Example 1. It can be clearly seen from the figure that the degradation effect of the SC-RF electrode is better than that of the HMC-RF electrode.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. The use of a modified sugar cane activated carbon electrode material, characterized in that, The modified sugarcane activated carbon electrode material is used to degrade non-steroidal drugs in wastewater, and the application is carried out under conditions that do not require aeration. The specific steps of the application include: using a ruthenium-iridium electrode as the anode and modified sugarcane activated carbon electrode material as the cathode, fixing the anode and cathode in a through-type reactor with a distance of 1 cm between the two electrodes; adding supporting electrolytes Na2SO4 and FeSO4 to the wastewater containing non-steroidal drugs to be degraded, and adjusting the pH to 3 with H2SO4 to obtain a reaction solution; drawing the reaction solution into the through-type reactor using a peristaltic pump to obtain an electro-Fenton system, and then degrading it by electricity; The modified sugarcane activated carbon electrode material is prepared through the following steps: (1) Fresh sugarcane or sugarcane bagasse after juicing is pretreated and then calcined and carbonized at 800~1000 ℃ under inert gas protection to obtain carbonized sugarcane; the carbonized sugarcane is activated at 700~800 ℃ for 10 h under CO2 atmosphere, and the activated sugarcane is ground to obtain carbon powder with porous structure. (2) Add carbon powder to anhydrous ethanol, then add polytetrafluoroethylene, heat and stir until a gel appears, and obtain activated carbon gel. (3) The activated carbon gel was coated onto the surface of the nickel foam, dried, pressed by a tablet press, and then calcined to obtain the sugarcane activated carbon electrode; (4) Pluronic F127, CoCl3·6H2O and CH3COOH were dissolved in water and stirred to prepare a mixed solution; sugarcane activated carbon electrode and 2-aminoterephthalic acid were added to the mixed solution and stirred to carry out a hydrothermal reaction to obtain modified sugarcane activated carbon electrode material.

2. Use according to claim 1, characterized in that, In step (1), the pretreatment includes: peeling the sugarcane, cutting it into sections and drying it to remove moisture, or drying the sugarcane residue after juicing, then ultrasonically cleaning it with water and ethanol to remove residual substances in the sugarcane, and then drying it after thorough cleaning.

3. Use according to claim 1, characterized in that, In step (1), the calcination and carbonization temperature is 900°C, and the activation temperature is 750°C; the average adsorption pore size of the carbon powder obtained is 2.05 nm.

4. Use according to claim 1, characterized in that, The heating temperature in step (2) is 80 ℃.

5. The use according to claim 1, characterized in that, In step (2), the mass ratio of carbon powder to polytetrafluoroethylene is 8:1, and the volume ratio of anhydrous ethanol to polytetrafluoroethylene is 20:

2.

6. Use according to claim 1, characterized in that, The drying temperature in step (3) is 60 °C; the calcination refers to calcination at 360 °C for 1 h under inert gas protection. The loading of the foam nickel surface activated carbon in step (3) is 0.05 g / cm 2 .

7. The use according to claim 1, characterized in that, In step (4), the amounts of Pluronic F127, CoCl3·6H2O, CH3COOH and 2-aminoterephthalic acid are 360 ​​parts by mass, 400 parts by mass, 0.6 parts by volume, and 136 parts by mass, respectively.

8. The use according to claim 1, characterized in that, The hydrothermal reaction mentioned in step (4) refers to heating at 110 °C for 24 h.

9. A modified sugarcane activated carbon electrode material prepared by the preparation method of the modified sugarcane activated carbon electrode material in any one of the applications described in claims 1 to 8.

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