Modified activated carbon fiber composite material, preparation method and application thereof, and method for degrading organic pollutants by heterogeneous electro-fenton oxidation

Abstract

The application relates to the technical field of electrochemical wastewater treatment, and discloses a modified activated carbon fiber composite material, a preparation method and application thereof, and a method for degrading organic pollutants through heterogeneous electro-Fenton oxidation. The preparation method of the composite material comprises the following steps: (1) contacting activated carbon fiber with organic acid to obtain pretreated activated carbon fiber; (2) in the presence of water, first mixing the pretreated activated carbon fiber with copper nitrate, silver nitrate and a surfactant to obtain mixture I; (3) second mixing the mixture I with ascorbic acid to obtain mixture II; and (4) carrying out a precipitation reaction of the mixture II with an alkali solution, and then standing to obtain the modified activated carbon fiber composite material. The modified activated carbon fiber composite material provided by the application has excellent adsorption and degradation effects on organic pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical wastewater treatment, and particularly relates to a modified activated carbon fiber composite material, a preparation method and application thereof, and a method for degrading organic pollutants by heterogeneous electro-Fenton oxidation. BACKGROUND

[0002] The electro-Fenton technology uses an electrochemical reaction to generate Fenton reagents (Fe 2+ and H2O2) in situ, thereby generating ·OH through Fenton reaction to achieve oxidative decomposition of organic pollutants. This technology can continuously generate H2O2 in situ at the cathode, effectively avoiding transportation and storage of H2O2, and achieving recycling of Fe 2+ , greatly reducing the use of Fe 2+ and the generation of iron sludge. So far, the electro-Fenton technology has been successfully used for removal of various refractory organic pollutants in water. However, the effective pH value of the Fenton reaction is generally between 2.0 and 4.0, and when the pH value is greater than 4.0, flocculation and precipitation of iron sludge will occur, causing secondary pollution and loss of iron active species, and the homogeneous catalyst is difficult to recycle, thereby limiting its practical application and use range.

[0003] CN114505101A discloses an organic dye degradation catalyst based on a heterogeneous Fenton-like reaction. The organic dye degradation catalyst is a two-dimensional grid-shaped metal organic framework that can catalyze the decomposition of H2O2 into ·OH with strong oxidizing properties. In addition, ultrasonic assistance not only improves the specific surface area and mesoporous structure of MOFs, but also enhances the charge transfer between the catalytic active sites. Combined with the synergistic catalytic effect of three metal ions, the catalytic activity of the metal organic framework is greatly enhanced, achieving the purpose of efficiently degrading organic pollutants. However, additional hydrogen peroxide is required during the degradation of organic dyes, and the catalyst needs to be dispersed in water, and the subsequent recovery and separation process is relatively complex.

[0004] CN114618592A discloses a preparation method of a high-efficiency heterogeneous Fenton catalyst. The preparation method uses a solvothermal method to prepare a FeOCl@Fe-MOFs heterogeneous Fenton catalyst with a core-shell structure. The catalyst uses the strong adsorption property of Fe-MOFs to adsorb organic pollutants in wastewater onto the surface of the catalyst, and at the same time, strengthens the interaction between Fe active sites and H2O2, accelerates the transfer of electrons from H2O2 to Fe(III), and accelerates the conversion of Fe(III) to Fe(II), thereby catalyzing the rapid decomposition of H2O2 to generate more hydroxyl radicals, and enhancing the oxidative degradation of organic pollutants in water. However, in the application of Fe-MOFs in the Fenton-like system, there are problems such as secondary pollution caused by leakage of Fe element and deactivation of the catalyst after long-term storage.

[0005] Therefore, it is very important to design and develop new non-ferrous Fenton system and Fenton-like catalyst. SUMMARY

[0006] The present application aims to overcome the problems of low degradation rate of organic pollutants and narrow pH range of existing Fenton-like materials.

[0007] In the research process, it is found that the organic acid is used to pretreat the activated carbon fiber, which increases the number of micropores on the surface of the activated carbon fiber, improves the specific surface area of the activated carbon fiber, and at the same time, the organic acid is adsorbed on the surface of the activated carbon fiber, which can form a complex with copper ions, thereby improving the loading rate of cuprous oxide and elemental silver. The pretreated activated carbon fiber is soaked in a mixed solution of copper ions and silver ions, and an in-situ precipitation reaction is carried out to realize the formation of nano-cuprous oxide and its deposition and loading on the surface or micropores of the pretreated activated carbon fiber, thereby improving the degradation rate of the modified activated carbon fiber composite material in the heterogeneous electro-Fenton oxidation degradation system.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of a modified activated carbon fiber composite material, which comprises the following steps:

[0009] (1) contacting activated carbon fiber with organic acid to obtain pretreated activated carbon fiber;

[0010] The organic acid is acetic acid and / or citric acid; the concentration of the organic acid is 1.2-1.5 mol / L;

[0011] (2) in the presence of water, the pretreated activated carbon fiber is first mixed with copper nitrate, silver nitrate and a surfactant to obtain a mixture I;

[0012] (3) the mixture I is secondly mixed with ascorbic acid to obtain a mixture II;

[0013] (4) the mixture II is subjected to a precipitation reaction with an alkali solution, and is left to stand to obtain a modified activated carbon fiber composite material;

[0014] The alkali solution is a sodium hydroxide solution and / or a potassium hydroxide solution; the concentration of the alkali solution is 0.1-1 mol / L;

[0015] The specific surface area of the activated carbon fiber is 1200-1600 m 2 / g, the average pore size is 1.0-2.0 nm, and the pore volume is 0.8-1.2 cm 3 / g.

[0016] The second aspect of the present application provides a modified activated carbon fiber composite material prepared by the method of the first aspect.

[0017] The third aspect of the present application provides application of the modified activated carbon fiber composite material of the second aspect as a cathode material in heterogeneous electro-Fenton oxidation degradation of organic pollutants.

[0018] The fourth aspect of the present application provides a method for heterogeneous electro-Fenton oxidation degradation of organic pollutants, which comprises the following steps:

[0019] The modified activated carbon fiber composite material of the second aspect is used as a cathode, and a conductive material is used as an anode; the cathode and the anode are placed in an electrolyte containing organic pollutants, air is blown into the electrolyte, and a heterogeneous electro-Fenton oxidation degradation reaction is carried out by applying electricity.

[0020] The modified activated carbon fiber composite material provided by the present application can realize efficient adsorption and degradation of pollutants; cuprous oxide in the composite material contains Cu + , which can effectively stimulate the generation of ·OH with strong oxidizing property from H2O2; at the same time, when the composite material is applied to a heterogeneous electro-Fenton oxidation degradation system, additional H2O2 and catalysts can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is an X-ray diffraction (XRD) characterization diagram of the modified activated carbon fiber composite material A1 prepared in Example 1.

[0022] Figure 2 is an elemental analysis diagram of the modified activated carbon fiber composite material A1 prepared in Example 1.

[0023] Figure 3 is an X-ray photoelectron spectroscopy (XPS) diagram of the modified activated carbon fiber composite material A1 prepared in Example 1.

[0024] Figure 4 is a catalytic degradation rate curve diagram of the modified activated carbon fiber composite material A1 prepared in Example 1 for methyl blue under different pH conditions (pH values are 3, 4, 5, 7, and 8).

[0025] Figure 5 is a cyclic test effect diagram of the modified activated carbon fiber composite material A1 prepared in Example 1 in a heterogeneous electro-Fenton oxidation degradation experiment. DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to also include any value approximately or about the value. For numeric ranges, the endpoints are combined with the single points to form new numeric ranges, which are to be construed as being specifically disclosed.

[0027] As described previously, the first aspect of the present application provides a method for preparing a modified activated carbon fiber composite material, the method comprising the following steps:

[0028] (1) contacting activated carbon fiber with organic acid to obtain pretreated activated carbon fiber;

[0029] The organic acid is acetic acid and / or citric acid; the concentration of the organic acid is 1.2-1.5 mol / L;

[0030] (2) first mixing the pretreated activated carbon fiber with copper nitrate, silver nitrate and surfactant in the presence of water to obtain mixture I;

[0031] (3) second mixing the mixture I with ascorbic acid to obtain mixture II;

[0032] (4) precipitating the mixture II with an alkali solution, and standing to obtain the modified activated carbon fiber composite material;

[0033] The alkali solution is sodium hydroxide solution and / or potassium hydroxide solution; the concentration of the alkali solution is 0.1-1 mol / L;

[0034] The specific surface area of the activated carbon fiber is 1200-1600 m 2 / g, the average pore size is 1.0-2.0 nm, and the pore volume is 0.8-1.2 cm 3 / g.

[0035] The specific surface area, the average pore size and the pore volume of the activated carbon fiber in the present application can be determined according to nitrogen adsorption-desorption experiments.

[0036] Preferably, the method further comprises: before the contacting, washing the activated carbon fiber with deionized water for 2-3 times, then contacting the washed activated carbon fiber with the organic acid, filtering, and then sequentially washing and drying the filtered activated carbon fiber to obtain the pretreated activated carbon fiber.

[0037] Preferably, the drying conditions include: temperature of 75-85℃, and time of 0.5-1h.

[0038] Preferably, the contacting in step (1) is performed for 6-8 hours.

[0039] Preferably, the activated carbon fiber is an activated carbon fiber felt. More preferably, the activated carbon fiber has a size of 1 cm x 1 cm-4 cm x 4 cm and a thickness of 1-5 mm.

[0040] Preferably, the amount of the organic acid used is 40-60 mL with respect to the activated carbon fiber having an area of 2 cm x 2 cm.

[0041] Preferably, in step (2), the amounts of copper nitrate and silver nitrate are controlled such that the molar ratio of copper ions to silver ions in mixture I is 5-10:1.

[0042] Preferably, in step (2), the amount of water is controlled such that the concentration of copper ions in mixture I is 0.08-0.12 mol / L.

[0043] Preferably, in step (2), the amount of the surfactant used is 25-35 g with respect to 1 L of water.

[0044] Preferably, the surfactant is at least one selected from polyethylene glycol, polyvinylpyrrolidone, and sodium dodecylsulfonate.

[0045] Preferably, in step (3), the amount of ascorbic acid used is 0.8-1.2 mol with respect to 1 mol of the total amount of copper nitrate and silver nitrate. In this preferred case, the loading amounts of cuprous oxide and silver in the modified activated carbon fiber composite are higher, so that the degradation rate of the modified activated carbon fiber composite for organic matter is improved.

[0046] Preferably, in step (3), the ascorbic acid is added in the form of an aqueous solution, and the concentration of the ascorbic acid aqueous solution is 0.16-0.24 mol / L.

[0047] Preferably, in step (4), the concentration of the alkali solution is 0.3-0.7 mol / L. The inventors have found that, in this preferred case, the formation of cuprous oxide on the activated carbon fiber is more favorable.

[0048] Preferably, the amount of the alkali solution used is 1-1.3 mol with respect to 1 mol of the total amount of copper nitrate, silver nitrate, and ascorbic acid.

[0049] According to one preferred embodiment, in step (2), the conditions of the first mixing include a temperature of 35-45°C, a time of 25-35 min, and a stirring speed of 400-850 rpm.

[0050] According to another preferred embodiment, in step (3), the conditions of the second mixing include: temperature of 30-40℃, time of 3-7min, and stirring speed of 100-250rpm.

[0051] Preferably, in step (4), the conditions of the precipitation reaction include: temperature of 40-50℃, and time of 1-1.5h. According to the inventors, in this preferred case, the generation of cuprous oxide on the activated carbon fiber is more favorable. If the temperature is too high, the reaction of dehydrating copper hydroxide to generate copper oxide precipitate is prone to occur.

[0052] In the present application, the precipitation reaction is preferably carried out under stirring conditions to make the reaction more complete. The stirring speed can be selected by those skilled in the art as needed.

[0053] Preferably, in step (4), the standing time is 12-24h. In this preferred case, the loading amount of cuprous oxide and silver in the modified activated carbon fiber composite obtained is higher, so that the degradation rate of the modified activated carbon fiber composite on organic matter is improved.

[0054] Preferably, the method further comprises: sequentially washing the precipitate obtained after the standing in step (4), and drying to constant weight to obtain the modified activated carbon fiber composite.

[0055] As described above, the second aspect of the present application provides a modified activated carbon fiber composite prepared by the method of the first aspect.

[0056] As described above, the third aspect of the present application provides the use of the modified activated carbon fiber composite of the second aspect as a cathode material in the heterogeneous electro-Fenton oxidation degradation of organic pollutants.

[0057] As described above, the fourth aspect of the present application provides a method for the heterogeneous electro-Fenton oxidation degradation of organic pollutants, which comprises the following steps:

[0058] The modified activated carbon fiber composite of the second aspect is used as a cathode, and a conductive material is used as an anode; the cathode and the anode are placed in an electrolyte containing organic pollutants, air is blown into the electrolyte, and a heterogeneous electro-Fenton oxidation degradation reaction is carried out by applying electricity.

[0059] Preferably, the conductive material is selected from one of a platinum electrode, a glassy carbon electrode, and a gold electrode.

[0060] Preferably, the organic pollutants in the electrolyte are selected from at least one of methyl blue, methyl orange, and rhodamine B. Preferably, the concentration of the organic pollutants in the electrolyte is 50-150mg / L.

[0061] Preferably, the flow rate of the air is 190-210 mL / min.

[0062] Preferably, the conditions of the heterogeneous electro-Fenton oxidation degradation reaction include: the current is 20-30 mA / cm 2 , and the time is 30-120 min.

[0063] The present application is preferably carried out under stirring when carrying out the heterogeneous electro-Fenton oxidation degradation, and the present application does not have a particular limitation on the rotating speed of the stirring, which can be selected by a person skilled in the art as needed.

[0064] In order to improve the degradation rate of the organic pollutants, the present application provides a preferred method for heterogeneous electro-Fenton oxidation degradation of the organic pollutants, which comprises the following steps:

[0065] The Pt sheet electrode with a size of 20 mm*20 mm is used as the anode of the reaction, the modified activated carbon fiber composite material with a size of 2 cm*2 cm is used as the cathode, the cathode and the anode are placed in 180-220 mL of the electrolyte containing the organic pollutants and having a concentration of 50-150 mg / L, then the air is blown into the electrolyte containing the organic pollutants at a flow rate of 190-210 mL / min, and the heterogeneous electro-Fenton oxidation degradation is carried out by power supply; during the heterogeneous electro-Fenton oxidation degradation, the current is provided by the adjustable constant voltage direct current power supply, the current intensity is 20-30 mA / cm 2 , and the test time is 30-120 min.

[0066] Compared with the prior art, the present application has the beneficial effects:

[0067] (1) The modified activated carbon fiber composite material provided by the present application is less affected by the pH value of the system during the reaction process of the homogeneous electro-Fenton oxidation degradation system, and for most industrial wastewater and domestic sewage, good degradation effect can be achieved without pH value adjustment, which overcomes the problem that the traditional Fenton method cannot be widely applied due to the harsh pH requirement and the sludge produced.

[0068] (2) The electrochemical generation of H2O2 in the present application is generated by the reduction of oxygen under the condition of cathode oxygenation or aeration, which reduces the cost of H2O2 external feeding.

[0069] (3) The modified activated carbon fiber composite material of the present application has excellent stability in the process of removing the organic pollutants, and is easy to recycle as an electrode material.

[0070] (4) The cuprous oxide in the modified activated carbon fiber composite material of the present application contains Cu +, which can effectively stimulate the production of H2O2 with strong oxidizing ·OH, ·OH non-selective attack on pollutants, and excellent catalytic degradation effect on pollutants.

[0071] The application will be described in detail below by examples. In the following examples, the various raw materials used are commercially available products, unless otherwise specified. In the examples, room temperature refers to 22±3℃.

[0072] Materials:

[0073] Platinum sheet electrode, purchased from Shanghai Yueci Electronics Technology Co., Ltd., model 20*20*0.1mm platinum sheet electrode.

[0074] Activated carbon fiber I, specific surface area 1400m 2 / g, average pore size 1.8nm, pore volume 1.0cm 3 / g, purchased from Hebei Ruaitai Environmental Protection Technology Co., Ltd., model SY-1500.

[0075] Activated carbon fiber II, specific surface area 1250m 2 / g, average pore size 2.0nm, pore volume 0.8cm 3 / g, purchased from Hebei Ruaitai Environmental Protection Technology Co., Ltd., model SY-1300.

[0076] Activated carbon fiber III, specific surface area 1000m 2 / g, average pore size 1.8nm, pore volume 0.9cm 3 / g, purchased from Hebei Ruaitai Environmental Protection Technology Co., Ltd., model SY-1000.

[0077] Instrument:

[0078] COD tester: manufacturer Hashi, model DR1010 portable COD tester;

[0079] X-ray diffraction (XRD) instrument: manufacturer Japan Science Corporation, model Ultima IV X-ray diffractometer;

[0080] Elemental analyzer: manufacturer Japan Electronics (JEOL), model JEM-2100F transmission electron microscope;

[0081] X-ray photoelectron spectroscopy (XPS) instrument: manufacturer Shimadzu, model AXIS SUPRA + X-ray photoelectron spectrometer.

[0082] Example 1

[0083] A modified activated carbon fiber composite material preparation method comprises the following steps:

[0084] (1) 2 cm x 2 cm x 5 mm activated carbon fiber I was washed with deionized water for 3 times, then the washed activated carbon fiber I was contacted with 1.4 mol / L citric acid (50 mL) at room temperature for 8 h, filtered, and then the filtered activated carbon fiber was washed with deionized water for 3 times and dried at 80°C for 0.5 h to obtain a pretreated activated carbon fiber;

[0085] (2) The pretreated activated carbon fiber of step (1) was first mixed with 0.01 mol of copper nitrate trihydrate, 0.001 mol of silver nitrate, and 3.0 g of polyethylene glycol in the presence of 100 mL of water to obtain a mixture I;

[0086] The first mixing condition was that the temperature was 40°C, the time was 30 min, and the stirring speed was 500 rpm;

[0087] (3) The mixture I obtained in step (2) was second mixed with 50 mL of 0.2 mol / L ascorbic acid to obtain a mixture II;

[0088] The second mixing condition was that the temperature was 40°C, the time was 5 min, and the stirring speed was 250 rpm;

[0089] (4) The mixture II was precipitated with 50 mL of 0.5 mol / L NaOH solution at 200 rpm, and then the obtained precipitate was washed with deionized water and anhydrous ethanol for 3 times, and dried to constant weight to obtain a modified activated carbon fiber composite material A1;

[0090] The precipitating reaction condition was that the temperature was 50°C, and the time was 1 h.

[0091] Example 2

[0092] A method for preparing a modified activated carbon fiber composite material, comprising the following steps:

[0093] (1) 2 cm x 2 cm x 5 mm activated carbon fiber II was washed with deionized water for 3 times, then the washed activated carbon fiber II was contacted with 1.2 mol / L citric acid (50 mL) at room temperature for 6 h, filtered, and then the activated carbon fiber after being contacted with the organic acid was washed with deionized water for 3 times and dried at 75°C for 1 h to obtain a pretreated activated carbon fiber;

[0094] (2) The pretreated activated carbon fiber of step (1) was first mixed with 0.012 mol of copper nitrate trihydrate, 0.002 mol of silver nitrate, and 3.5 g of sodium dodecyl sulfonate in the presence of 100 mL of water to obtain a mixture I;

[0095] The first mixing condition: temperature is 35℃, time is 35min, stirring speed is 700rpm;

[0096] (3) The mixture I obtained in step (2) is second mixed with 70mL 0.24mol / L ascorbic acid to obtain mixture II;

[0097] The second mixing condition: temperature is 30℃, time is 7min, stirring speed is 150rpm;

[0098] (4) The mixture II is precipitated with 46mL 0.7mol / L NaOH solution, and then the obtained precipitate is washed with deionized water and anhydrous ethanol for 3 times, and dried to constant weight to obtain modified activated carbon fiber composite material A2;

[0099] The precipitating reaction condition: temperature is 50℃, time is 1h.

[0100] Example 3

[0101] The present example is carried out by using the similar method of example 1, except that in step (2), the amount of copper nitrate is 0.008mol, and the amount of silver nitrate is 0.003mol;

[0102] The remaining steps are the same as example 1, and the modified activated carbon fiber composite material A3 is prepared.

[0103] Example 4

[0104] The present example is carried out by using the similar method of example 1, except that in step (2), the amount of polyethylene glycol is 4g;

[0105] The remaining steps are the same as example 1, and the modified activated carbon fiber composite material A4 is prepared.

[0106] Comparative example 1

[0107] The present comparative example is carried out by using the similar method of example 1, except that 1.4mol / L citric acid in step (1) is replaced by 1.4mol / L sulfuric acid;

[0108] The remaining steps are the same as example 1; and the modified activated carbon fiber composite material DA1 is prepared.

[0109] Comparative example 2

[0110] The present comparative example is carried out by using the similar method of example 1, except that 50mL 0.2mol / L ascorbic acid in step (3) is replaced by 50mL 0.2mol / L glucose;

[0111] The remaining steps are the same as in Example 1; a modified activated carbon fiber composite material DA2 is prepared.

[0112] Comparative Example 3

[0113] This comparative example is carried out in a similar manner to Example 1, except that 50 mL of 0.2 mol / L ascorbic acid in step (3) is replaced by 50 mL of 0.2 mol / L hydrazine;

[0114] The remaining steps are the same as in Example 1; a modified activated carbon fiber composite material DA3 is prepared.

[0115] Comparative Example 4

[0116] This comparative example is carried out in a similar manner to Example 1, except that 50 mL of 1 mol / L sodium hydroxide solution in step (4) is replaced by 25 mL of 2 mol / L sodium hydroxide solution;

[0117] The remaining steps are the same as in Example 1; a modified activated carbon fiber composite material DA4 is prepared.

[0118] Comparative Example 5

[0119] This comparative example is carried out in a similar manner to Example 1, except that 50 mL of 1 mol / L sodium hydroxide solution in step (4) is replaced by 50 mL of 1 mol / L ammonia;

[0120] The remaining steps are the same as in Example 1; a modified activated carbon fiber composite material DA5 is prepared.

[0121] Comparative Example 6

[0122] This comparative example is carried out in a similar manner to Example 1, except that 2 cm x 2 cm activated carbon fiber I in step (1) is replaced by 2 cm x 2 cm activated carbon fiber III;

[0123] The remaining steps are the same as in Example 1; a modified activated carbon fiber composite material DA6 is prepared.

[0124] Test Example 1

[0125] The modified activated carbon fiber composite material prepared in the above example is used as a cathode material for heterogeneous electro-Fenton oxidation degradation of organic pollutants; the method comprises the following steps:

[0126] A 200 mL methyl blue solution with a concentration of 100 mg / L was used as simulated wastewater, a 20 mm x 20 mm Pt sheet electrode was used as the anode of the reaction, and the modified activated carbon fiber composite material prepared in the above examples was used as the cathode, 200 mL of the 100 mg / L methyl blue solution was added to a beaker, then air was blown into the methyl blue solution at a flow rate of 200 mL / min, and power was supplied to form a heterogeneous electro-Fenton oxidation degradation system, and the heterogeneous electro-Fenton oxidation degradation reaction was carried out; during the heterogeneous electro-Fenton oxidation degradation process, a current was provided by an adjustable constant voltage direct current power supply, and the current intensity was 30 mA / cm 2 , and the solution was homogenized by a magnetic stirrer.

[0127] At room temperature, the upper clear liquid of 2 mL of the methyl blue solution was taken out every 30 min, the absorbance was measured in a UV-visible spectrophotometer, and the concentration was converted, and a degradation rate curve was drawn; at the same time, the chemical oxygen demand COD was measured by a rapid digestion spectrophotometric method, and a COD removal rate curve was drawn, wherein the calculation formulas of the COD removal rate and the degradation rate are as follows:

[0128] COD removal rate = (COD0-COD t ) / COD0x 100% formula (1);

[0129] In formula (1), COD0represents the initial chemical oxygen demand (mg / L);

[0130] COD t represents the chemical oxygen demand (mg / L) at t in the reaction process;

[0131] Degradation rate = (C0-C t ) / C0x 100% formula (2);

[0132] In formula (2), C0represents the initial absorbance corresponding concentration (mg / L); C t represents the absorbance corresponding concentration (mg / L) at t in the reaction process;

[0133] The COD removal rate and the degradation rate after the heterogeneous electro-Fenton oxidation degradation reaction was carried out for 120 min are shown in Table 1.

[0134] Table 1

[0135] Modified activated carbon fiber composite COD removal rate / % Degradation rate / % A1 90.43 92.84 A2 89.71 89.52 A3 85.91 87.17 A4 84.57 82.41 DA1 70.16 74.58 DA2 79.72 78.11 DA3 75.64 73.29 DA4 74.18 74.80 DA5 46.75 53.16 DA6 77.46 79.87

[0136] As can be seen from the above table, when the modified activated carbon fiber composite material is used as the cathode for the heterogeneous electro-Fenton oxidation degradation of organic pollutants, the catalytic degradation effect of the modified activated carbon fiber composite material on the pollutants methylene blue is excellent.

[0137] Meanwhile, the application exemplarily provides X-ray diffraction (XRD) characterization of the modified activated carbon fiber composite material A1 prepared in Example 1, and the result is shown in Figure 1 As shown in Figure 1 It can be seen that by comparing the XRD spectrum of the sample with the spectrum standard card of Cu2O and Ag element, it is proved that Cu2O and elemental silver particles exist in the modified activated carbon fiber composite material, that is, the activated carbon fiber composite material is modified by cuprous oxide and silver.

[0138] The application exemplarily provides elemental analysis of the modified activated carbon fiber composite material A1 prepared in Example 1, and the result is shown in Figure 2 As shown in Figure 2 It can be seen that the modified activated carbon fiber composite material A1 mainly has four elements of C (red), O (blue), Cu (purple) and Ag (orange) on the surface, and the distribution is very uniform.

[0139] The application exemplarily provides X-ray photoelectron spectroscopy (XPS) of the modified activated carbon fiber composite material A1 prepared in Example 1, and the result is shown in Figure 3 As shown in Figure 3 It can be seen that the sample mainly has four elements of C, O, Cu and Ag on the surface, and the existence of Cu2p3 peak and Ag3d peak, which confirms that the modified activated carbon fiber composite material A1 has cuprous oxide and elemental silver.

[0140] The application exemplarily provides degradation rate of methyl blue of the modified activated carbon fiber composite material A1 prepared in Example 1 as a cathode under different pH conditions (pH values are 3, 4, 5, 7 and 8), and the result is shown in Figure 4 As shown in Figure 4 It can be seen that the cuprous oxide and silver modified activated carbon fiber composite material has little influence on the pH value of the system in the process of homogeneous electro-Fenton oxidation degradation reaction. When the pH value is in the range of 3-8, the maximum and minimum of the degradation rate only differ by 9.3%, which shows that the material can solve the problem of narrow pH application range of the traditional iron-based Fenton catalyst.

[0141] Test Example 2 Repetitive Experiment

[0142] In the above heterogeneous electro-Fenton oxidation degradation experiment, the modified activated carbon fiber composite material A1 after 120 min of electro-catalytic test is taken out, washed with deionized water for 3 times to wash away the adsorbed organic pollutants, and then dried in a vacuum drying box at 60℃, and then the next cycle test is carried out. The next cycle test still follows the test method in Test Example 1, and the process is repeated for 4 times, and the experimental result is shown in Figure 5 .

[0143] From Figure 5It can be seen that the treatment effect of the heterogeneous electro-Fenton system of the modified activated carbon fiber composite material A1 is very stable, and the removal rates of methylene blue are 92.84%, 92.12%, 90.83%, 89.88% and 91.53% respectively. The difference in the removal rate of methylene blue after five repeated uses is controlled within 3%, which indicates that the modified activated carbon fiber composite material has good stability and excellent electrochemical performance in the heterogeneous electro-Fenton catalysis.

[0144] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for preparing a modified activated carbon fiber composite material for heterogeneous electro-Fenton oxidation degradation of organic pollutants, characterized by, The method comprises the following steps: (1) contacting activated carbon fiber with organic acid to obtain pretreated activated carbon fiber; The organic acid is acetic acid and / or citric acid; the concentration of the organic acid is 1.2-1.5 mol / L; (2) in the presence of water, first mixing the pretreated activated carbon fiber with copper nitrate, silver nitrate and surfactant to obtain mixture I; (3) second mixing the mixture I with ascorbic acid to obtain mixture II; (4) precipitating reaction of the mixture II with alkali solution, and standing to obtain modified activated carbon fiber composite material; The alkali solution is sodium hydroxide solution and / or potassium hydroxide solution; the concentration of the alkali solution is 0.1-1 mol / L; The activated carbon fiber has a specific surface area of 1200-1600 m 2 / g, an average pore diameter of 1.0-2.0 nm, and a pore volume of 0.8-1.2 cm 3 / g; The conditions of the precipitating reaction include: temperature is 40-50℃, and time is 1-1.5h.

2. The method of claim 1, wherein, The activated carbon fiber is activated carbon fiber felt; and / or In step (2), the amount of copper nitrate and silver nitrate is controlled so that the molar ratio of copper ions to silver ions in mixture I is 5-10:1; and / or In step (2), the amount of water is controlled so that the concentration of copper ions in mixture I is 0.08-0.12 mol / L.

3. The method of claim 1 or 2, wherein, In step (2), the amount of surfactant is 25-35g relative to 1L of water; and / or The surfactant is selected from at least one of polyethylene glycol, polyvinylpyrrolidone and sodium dodecyl sulfonate.

4. The method of claim 1 or 2, wherein, In step (3), the amount of ascorbic acid is 0.8-1.2 mol based on 1 mol of the total amount of copper nitrate and silver nitrate; and / or In step (3), the ascorbic acid is added in the form of aqueous solution, and the concentration of the ascorbic acid aqueous solution is 0.16-0.24 mol / L.

5. The method of claim 4, wherein, In step (4), the concentration of the alkali solution is 0.3-0.7 mol / L; The amount of the alkali solution is 1-1.3 mol based on 1 mol of the total molar amount of copper nitrate, silver nitrate and ascorbic acid.

6. The method of claim 1 or 2, wherein, In step (2), the conditions of the first mixing include: temperature is 35-45℃, time is 25-35 min, and stirring speed is 400-850 rpm; and / or In step (3), the conditions of the second mixing include: temperature is 30-40℃, time is 3-7 min, and stirring speed is 100-250 rpm; and / or In step (4), the standing time is 12-24h.

7. Modified activated carbon fiber composite material prepared by the method of any one of claims 1-6.

8. Application of the modified activated carbon fiber composite material of claim 7 as cathode material in heterogeneous electro-Fenton oxidation degradation of organic pollutants.

9. A method for the heterogeneous electro-Fenton oxidation of organic pollutants, characterized in that, The method comprises the following steps: Taking the modified activated carbon fiber composite material of claim 7 as cathode and taking conductive material as anode; placing the cathode and anode in electrolyte containing organic pollutants, bubbling air in the electrolyte, and conducting electro-Fenton oxidation degradation reaction.

10. The method of claim 9, wherein, The conductive material is selected from one of platinum electrode, glassy carbon electrode and gold electrode.

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