Disclosure of Invention
The invention aims to provide preparation and application of a supported trimetal carbon nanofiber electro-Fenton cathode202,H202Reacts with iron ions, zinc ions or cobalt ions loaded on the surface of the cathode to generate OH, and the antibiotic enrofloxacin is oxidatively degraded.
The invention solves the key technical problem of preparing a Fe/Co/Zn Co-doped zeolite-like imidazole framework material (Fe-Co-Zn-ZIF @ PAN) growing on the surface of an electrostatic spinning Polyacrylonitrile (PAN) nanofiber blended by MIM and PAN in situ, calcining and carbonizing the material at 500-900 ℃ in a tube furnace to obtain a metal and nitrogen Co-doped carbon nanofiber composite material (Fe/Co/Zn @ C-NCNFs), wherein the composite material has a large specific surface area (74.2220-108.0131 m)2Per gram) and pore volume (0.0899-0.1109 cm)3(g), a higher reduction potential (0.2468-0.7225V) and a faster electron transfer rate. Then Fe/Co/Zn @ C-NCNFs were loaded on the pretreated carbon felt to prepare an out-of-phase electro-Fenton cathode (Fe/Co/Zn @ C-NCNFs-CF), and an out-of-phase electro-Fenton system was constructed using the cathode.
The invention solves another technical problem of application of the heterogeneous electro-Fenton cathode in water samples containing enrofloxacin. The test result shows that after five times of continuous operation, the cathode still has higher enrofloxacin removal rate (more than or equal to 93 percent) and lower metal ion leaching rate (Fe is less than or equal to 0.35mg/L, Co is less than or equal to 0.14mg/L, and Zn is less than or equal to 0.82 mg/L).
The technical scheme of the invention is as follows.
A preparation method of a trimetal carbon nanofiber-loaded electro-Fenton cathode comprises the following steps:
(1) 2-methylimidazole (MIM) and Polyacrylonitrile (PAN) are blended, and the MIM/PAN precursor nanofiber is prepared by adopting an electrostatic spinning method: dissolving 2-methylimidazole and polyacrylonitrile in an N, N-dimethylformamide solution, and carrying out electrospinning after stirring; spinning speed is 0.6-0.8 mL/h, the distance from a collector to a needle is 15cm, spinning voltage is 20kV, temperature is 25 +/-1 ℃, and humidity is 30 +/-10%, so that an MIM/PAN precursor is obtained;
(2) growing Fe/Co/Zn Co-doped zeolite-like imidazole framework material (Fe-Co-Zn-ZIF @ PAN) in situ on MIM/PAN precursor: soaking the MIM/PAN precursor obtained in the step (1) in 50mL of methanol solution containing metal salt, wherein the metal salt is FeCl2·4H2O(1~3mmol)、CoCl2·6H2O (1-3 mmol) and Zn (NO)3)2·6H2O (1-3 mmol); then, pouring a methanol solution containing 2-methylimidazole into the solution to promote the continuous growth of Fe-Co-Zn-ZIF; after aging at room temperature, washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) calcining and carbonizing the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane at 500-900 ℃ to obtain a metal and nitrogen Co-doped carbon nanofiber composite material Fe/Co/Zn @ C-NCNFs: and (3) heating the Fe-Co-Zn-ZIF @ PAN obtained in the step (2) from room temperature to 270-290 ℃ at a heating rate of 0.5-2 ℃/min in a tubular furnace, keeping the temperature in an air atmosphere for 1.5-2.5 h to stabilize a graphite carbon structure, and finally calcining and carbonizing the graphite carbon structure in the tubular furnace at 500-900 ℃ to obtain Fe/Co/Zn @ C-NCNFs.
(4) Dispersing Fe/Co/Zn @ C-NCNFs into a mixed solution of a Nafion solution and absolute ethyl alcohol, carrying out ultrasonic treatment, dropping the dispersed liquid of the catalyst onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60-80 ℃ to obtain a Fe/Co/Zn @ C-NCNFs-CF cathode; the pretreatment of the carbon felt comprises the steps of respectively soaking commercial carbon felt in nitric acid, acetone and deionized water, and then drying in vacuum to obtain the trimetal carbon nanofiber loaded electro-Fenton cathode.
In the method, in the step (1), the mass ratio of the 2-methylimidazole to the polyacrylonitrile is 1: 2-3; the volume of the N, N-dimethylformamide solution is 12 mL.
In the method, in the step (1), the stirring time is 8-12 hours.
In the method, in the step (2), the concentration of the methanol solution of 2-methylimidazole is 10-30 mmol; the volume of the methanol solution of the 2-methylimidazole is 10 mL; the aging time is 8-12 h
In the method, in the step (4), the volume of the Nafion solution is 10 mu L, and the volume percentage concentration is 1-5%; the volume of the absolute ethyl alcohol is 1 ml.
In the method, in the step (4), the ultrasonic treatment time is 1-6 min; the concentration of the nitric acid is 0.5-1.5 mol/L.
The three-metal carbon nanofiber-loaded electro-Fenton cathode has a large specific surface area (74.2220-108.0131 m)2Per gram) and pore volume (0.0899-0.1109 cm)3(g), a higher reduction potential (0.2468-0.7225V) and a faster electron transfer rate.
The application of the supported trimetal carbon nanofiber electro-Fenton cathode (Fe/Co/Zn @ C-NCNFs-CF) is characterized in that in a heterogeneous electro-Fenton system, Fe/Co/Zn @ C-NCNFs-CF is used as the cathode, and dissolved oxygen in water is reduced to H at the cathode202,H202Reacting with iron ions, zinc ions or cobalt ions loaded on the surface of the carbon nanofiber cathode to generate hydroxyl free radicals, and oxidizing and degrading the antibiotic enrofloxacin.
Further, iron ions, zinc ions or cobalt ions loaded on the surface of the carbon nanofiber composite material can effectively activate H2O2Generation of OH with significant H2O2(130. + -. 5mg/L, 0.86. + -. 0.06mg/L/min) and OH (36. + -. 2mg/L, 0.24. + -. 0.03 mg/L/min).
Furthermore, after the cathode is repeatedly used for five times, the removal rate of 50mL of 10mg/L enrofloxacin in water is higher than 93%, and the cathode has lower leaching rate of metal ions (Fe: < 0.35mg/L, Co: < 0.14mg/L, Zn: < 0.82mg/L), namely the cathode has better repeatability and stability.
Further, the dissolved oxygen in the water is reduced on the surface of the trimetal carbon nanofiber electro-Fenton cathode to generate H2O2The conditions of (a) are as follows: the pH is 2-10 and the current is 10-100 mA.
Further, in the electro-Fenton system, a Pt sheet is used as an anode, a carbon nanofiber-loaded trimetal electro-Fenton cathode is used as a cathode, a two-electrode system is constructed, and 90mL of 0.1mol/L Na is used2SO4Is an electrolyte.
In the application system of the invention, air is injected into the cathode region, or the oxygen generated by electrolyzing water at the anode is utilized to generate H in situ2O2。
The invention adopts the Fe/Co/Zn @ C-NCNFs-CF composite material as the cathode, and has the characteristics of high specific surface area, excellent conductivity, good enrofloxacin degradation effect and the like.
Compared with the prior art, the invention has the following excellent effects:
(1) according to the invention, after the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane is carbonized at high temperature, the metal and nitrogen Co-doped carbon nanofiber composite material Fe/Co/Zn @ C-NCNFs is obtained. Iron ions, zinc ions and cobalt ions are uniformly loaded on the surface of the carbon nano-fiber, so that H is promoted to be produced by two-electron oxygen reduction2O2And activates H2O2OH is formed, has excellent H2O2(130. + -. 5mg/L, 0.86. + -. 0.06mg/L/min) and OH (36. + -. 2mg/L, 0.24. + -. 0.03 mg/L/min).
(2) Compared with the conventional Fenton technology, the Fe/Co/Zn @ C-NCNFs-CF composite material is used as a cathode for electrocatalysis, and no H is added outside2O2The catalyst does not cause secondary pollution, has no problem of subsequent catalyst recovery, and can regulate and control H by controlling current2O2The production rate and yield of enrofloxacin and the degradation rate of enrofloxacin.
(3) The electro-Fenton cathode prepared by the invention has better repeatability and stability, and after the cathode is continuously operated for five times, the cathode still has higher removal rate (more than or equal to 93%) and lower metal ion leaching rate (Fe is less than or equal to 0.35mg/L, Co is less than or equal to 0.14mg/L, and Zn is less than or equal to 0.82mg/L) on enrofloxacin.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
example 1
The preparation method of the tri-metal-loaded carbon nanofiber electro-Fenton cathode comprises the following steps:
(1) firstly, dissolving 0.70g of PAN and 0.30g of MIM in 10mL of N, N-dimethylformamide solution, magnetically stirring for 12h to prepare a blending liquid, transferring the blending liquid into a plastic capillary, and performing electrospinning under 20kV to obtain MIM/PAN precursor nanofiber;
(2) secondly, the obtained MIM/PAN precursor is soaked in 50mL of methanol-containing solution, and FeCl is added into the solution2·4H2O(2mmol)、CoCl2·6H2O (2mmol) and Zn (NO)3)2·6H2O (2mmol), after stirring for 1h, 10mL of a methanol solution containing MIM (30mmol) was poured into the above solution to promote the continuous growth of Fe-Co-Zn-ZIF. Aging for 8h at room temperature, and washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) thirdly, heating the obtained Fe-Co-Zn-ZIF @ PAN from room temperature to 280 ℃ at the heating rate of 1 ℃/min in a tubular furnace, keeping the temperature in the air atmosphere for 2 hours to stabilize a graphite carbon structure, and finally calcining and carbonizing the obtained Fe-Co-Zn-ZIF @ PAN in the tubular furnace at the temperature of 800 ℃ to obtain the Fe/Co/Zn @ C-NCNFs-800 nanocomposite;
(4) and fourthly, dispersing the Fe/Co/Zn @ C-NCNFs-800 nano composite material into 10 mu L of a mixed solution of 5% by volume of Nafion solution and 1mL of absolute ethyl alcohol, carrying out ultrasonic treatment for 1min, dripping the dispersed liquid of the nano composite material onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60 ℃ to obtain Fe/Co/Zn @ C-NCNFs-800-CF. The carbon felt is pretreated by immersing a commercial carbon felt in nitric acid, acetone and deionized water, respectively, and then vacuum-drying.
In an electron microscope image of the Fe/Co/Zn @ C-NCNFs-800 nanocomposite prepared in this example, as shown in FIG. 1, after calcination and carbonization at 800 ℃ in a tube furnace, Fe-Co-Zn-ZIF is converted into nanoparticles and dispersed on the surface of nanofibers.
The application of the embodiment: a Pt sheet is used as an anode, Fe/Co/Zn @ C-NCNFs-800-CF is used as a cathode, a two-electrode system is constructed, under the conditions that the pH is 3, the current is 40mA, and continuous aeration is performed near the cathode, the cathode can achieve 100% removal rate on 50mL of enrofloxacin with the concentration of 10mg/L, and the reaction rate constant is 0.0426/min.
Example 2
The preparation method of the tri-metal-loaded carbon nanofiber electro-Fenton cathode comprises the following steps:
(1) firstly, dissolving 0.70g of PAN and 0.30g of MIM in 10mL of N, N-dimethylformamide solution, magnetically stirring for 12h to prepare a blending liquid, transferring the blending liquid into a plastic capillary, and performing electrospinning under 20kV to obtain MIM/PAN precursor nanofiber;
(2) secondly, the obtained MIM/PAN precursor is soaked in 50mL of methanol-containing solution, and FeCl is added into the solution2·4H2O(2mmol)、CoCl2·6H2O (2mmol) and Zn (NO)3)2·6H2O (2mmol), after stirring for 1h, 10mL of a methanol solution containing MIM (30mmol) was poured into the above solution to promote the continuous growth of Fe-Co-Zn-ZIF. Aging for 8h at room temperature, and washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) thirdly, heating the obtained Fe-Co-Zn-ZIF @ PAN from room temperature to 280 ℃ at the heating rate of 1 ℃/min in a tubular furnace, keeping the temperature in the air atmosphere for 2 hours to stabilize a graphite carbon structure, and finally calcining and carbonizing the obtained Fe-Co-Zn-ZIF @ PAN in the tubular furnace at the temperature of 500 ℃ to obtain the Fe/Co/Zn @ C-NCNFs-500 nano composite material;
(4) and fourthly, dispersing the Fe/Co/Zn @ C-NCNFs-500 nano composite material into 10 mu L of mixed solution of Nafion solution with volume fraction of 5% and 1mL of absolute ethyl alcohol, carrying out ultrasonic treatment for 1min, dripping the dispersed liquid of the nano composite material onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60 ℃ to obtain Fe/Co/Zn @ C-NCNFs-500-CF. The carbon felt is pretreated by immersing a commercial carbon felt in nitric acid, acetone and deionized water, respectively, and then vacuum-drying.
The application of the embodiment: a Pt sheet is used as an anode, Fe/Co/Zn @ C-NCNFs-500-CF is used as a cathode, a two-electrode system is constructed, and under the conditions that the pH is 3, the current is 40mA, the reaction time is 20min and continuous aeration is carried out near the cathode, the removal rate of the cathode to 50mL of enrofloxacin with the concentration of 10mg/L is 30%.
Example 3
The preparation method of the tri-metal-loaded carbon nanofiber electro-Fenton cathode comprises the following steps:
(1) firstly, dissolving 0.70g of PAN and 0.30g of MIM in 10mL of N, N-dimethylformamide solution, magnetically stirring for 12h to prepare a blending liquid, transferring the blending liquid into a plastic capillary, and performing electrospinning under 20kV to obtain MIM/PAN precursor nanofiber;
(2) secondly, the obtained MIM/PAN precursor is soaked in 50mL of methanol-containing solution, and FeCl is added into the solution2·4H2O(2mmol)、CoCl2·6H2O (2mmol) and Zn (NO)3)2·6H2O (2mmol), after stirring for 1h, 10mL of a methanol solution containing MIM (30mmol) was poured into the above solution to promote the continuous growth of Fe-Co-Zn-ZIF. Aging for 8h at room temperature, and washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) thirdly, heating the obtained Fe-Co-Zn-ZIF @ PAN from room temperature to 280 ℃ at the heating rate of 1 ℃/min in a tubular furnace, keeping the temperature in the air atmosphere for 2 hours to stabilize a graphite carbon structure, and finally calcining and carbonizing at 600 ℃ in the tubular furnace to obtain the Fe/Co/Zn @ C-NCNFs-600 nano composite material;
(4) and fourthly, dispersing the Fe/Co/Zn @ C-NCNFs-600 nano composite material into 10 mu L of a mixed solution of a Nafion solution with the volume fraction of 5% and 1mL of absolute ethyl alcohol, carrying out ultrasonic treatment for 1min, dripping the dispersed liquid of the nano composite material onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60 ℃ to obtain Fe/Co/Zn @ C-NCNFs-600-CF. The carbon felt is pretreated by immersing a commercial carbon felt in nitric acid, acetone and deionized water, respectively, and then vacuum-drying.
The application of the embodiment: a Pt sheet is used as an anode, Fe/Co/Zn @ C-NCNFs-600-CF is used as a cathode, a two-electrode system is constructed, and under the conditions that the pH is 3, the current is 40mA, the reaction time is 20min and continuous aeration is carried out near the cathode, the removal rate of the cathode to 50mL of enrofloxacin with the concentration of 10mg/L is 32%.
Example 4
The preparation method of the tri-metal-loaded carbon nanofiber electro-Fenton cathode comprises the following steps:
(1) firstly, dissolving 0.70g of PAN and 0.30g of MIM in 10mL of N, N-dimethylformamide solution, magnetically stirring for 12h to prepare a blending liquid, transferring the blending liquid into a plastic capillary, and performing electrospinning under 20kV to obtain MIM/PAN precursor nanofiber;
(2) secondly, the obtained MIM/PAN precursor is soaked in 50mL of methanol-containing solution, and FeCl is added into the solution2·4H2O(2mmol)、CoCl2·6H2O (2mmol) and Zn (NO)3)2·6H2O (2mmol), after stirring for 1h, 10mL of a methanol solution containing MIM (30mmol) was poured into the above solution to promote the continuous growth of Fe-Co-Zn-ZIF. Aging for 8h at room temperature, and washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) thirdly, heating the obtained Fe-Co-Zn-ZIF @ PAN from room temperature to 280 ℃ at the heating rate of 1 ℃/min in a tubular furnace, keeping the temperature in the air atmosphere for 2 hours to stabilize a graphite carbon structure, and finally calcining and carbonizing the obtained Fe-Co-Zn-ZIF @ PAN in the tubular furnace at the temperature of 700 ℃ to obtain the Fe/Co/Zn @ C-NCNFs-700 nano composite material;
(4) and fourthly, dispersing the Fe/Co/Zn @ C-NCNFs-700 nano composite material into 10 mu L of mixed solution of Nafion solution with volume fraction of 5% and 1mL of absolute ethyl alcohol, carrying out ultrasonic treatment for 1min, dripping the dispersed liquid of the nano composite material onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60 ℃ to obtain Fe/Co/Zn @ C-NCNFs-700-CF. The carbon felt is pretreated by immersing a commercial carbon felt in nitric acid, acetone and deionized water, respectively, and then vacuum-drying.
The application of the embodiment: a Pt sheet is used as an anode, Fe/Co/Zn @ C-NCNFs-700-CF is used as a cathode, a two-electrode system is constructed, and under the conditions that the pH is 3, the current is 40mA, the reaction time is 20min, and continuous aeration is performed near the cathode, the removal rate of the cathode to 50mL of enrofloxacin with the concentration of 10mg/L is 72%.
Example 5
The preparation method of the tri-metal-loaded carbon nanofiber electro-Fenton cathode comprises the following steps:
(1) firstly, dissolving 0.70g of PAN and 0.30g of MIM in 10mL of N, N-dimethylformamide solution, magnetically stirring for 12h to prepare a blending liquid, transferring the blending liquid into a plastic capillary, and performing electrospinning under 20kV to obtain MIM/PAN precursor nanofiber;
(2) secondly, the obtained MIM/PAN precursor is soaked in 50mL of methanol-containing solution, and FeCl is added into the solution2·4H2O(2mmol)、CoCl2·6H2O (2mmol) and Zn (NO)3)2·6H2O (2mmol), after stirring for 1h, 10mL of a methanol solution containing MIM (30mmol) was poured into the above solution to promote the continuous growth of Fe-Co-Zn-ZIF. Aging for 8h at room temperature, and washing for several times by using methanol to obtain the Fe-Co-Zn-ZIF @ PAN electrostatic spinning nanofiber membrane;
(3) thirdly, heating the obtained Fe-Co-Zn-ZIF @ PAN from room temperature to 280 ℃ at the heating rate of 1 ℃/min in a tubular furnace, keeping the temperature in the air atmosphere for 2 hours to stabilize a graphite carbon structure, and finally calcining and carbonizing the obtained Fe-Co-Zn-ZIF @ PAN in the tubular furnace at the temperature of 900 ℃ to obtain the Fe/Co/Zn @ C-NCNFs-900 nanocomposite;
(4) and fourthly, dispersing the Fe/Co/Zn @ C-NCNFs-900 nano composite material into 10 mu L of a mixed solution of a Nafion solution with the volume fraction of 5% and 1mL of absolute ethyl alcohol, carrying out ultrasonic treatment for 1min, dripping the dispersed liquid of the nano composite material onto a pretreated Carbon Felt (CF), and drying in a vacuum drying oven at the temperature of 60 ℃ to obtain Fe/Co/Zn @ C-NCNFs-900-CF. The carbon felt is pretreated by immersing a commercial carbon felt in nitric acid, acetone and deionized water, respectively, and then vacuum-drying.
The application of the embodiment: a Pt sheet is used as an anode, Fe/Co/Zn @ C-NCNFs-900-CF is used as a cathode, a two-electrode system is constructed, and under the conditions that the pH is 3, the current is 40mA, the reaction time is 20min and continuous aeration is carried out near the cathode, the removal rate of the cathode to 50mL of enrofloxacin with the concentration of 10mg/L is 20%.
Example 6
The influence of the three-metal carbon nanofiber loaded electro-Fenton cathode on the removal effect of enrofloxacin under different applied current conditions:
a two-electrode system was constructed using a Pt sheet as an anode and the cathode prepared in example 1 as a cathode, and the removal rate of 50mL of 10mg/L enrofloxacin was determined by the cathode under conditions of pH 3, reaction time of 20min and continuous aeration near the cathode at a current of 10 to 100mA, and the results are shown in Table 1. It can be seen that the removal rate of enrofloxacin is significantly increased as the current is increased from 10mA to 40mA, and the removal rate of enrofloxacin is close to 100% at a current of 40 mA. High current can effectively promote H2O2And the continuous production of OH, so that the removal of enrofloxacin is facilitated under the high current condition. Thereafter, the removal rate of enrofloxacin was gradually decreased as the current was increased, and when the current was 100mA, the removal rate of enrofloxacin was only 77%, which is probably because H was caused by a higher current2O2Further reduction and consumption.
TABLE 1 Effect of Current on enrofloxacin removal
Example 7
The three-metal carbon nanofiber loaded electro-Fenton cathode is used for H under different applied current conditions2O2And effect of OH yield:
using a Pt sheet as an anode and the cathode prepared in example 1 as a cathode, a two-electrode system was constructed at pH3, the reaction time is 150min, and under the condition of continuous aeration near the cathode, when the current is 10-100 mA, the cathode reacts with H in the electro-Fenton reaction process2O2And OH yield, the results are shown in Table 2. In the initial stage, H is increased when the applied current is increased from 10mA to 40mA2O2Increases the yield of OH from 25mg/L to 130mg/L and increases the yield of OH from 22mg/L to 36 mg/L. However, when the applied current was increased to 100mA, H2O2And OH yields are all significantly reduced, H2O2The OH yields were reduced by 55% (58mg/L) and 25% (27mg/L), respectively. At an applied current of 40mA, H2O2And OH, the highest concentration, further confirming that enrofloxacin removed the best at 40 mA.
TABLE 2 Current vs. H2O2Effect of the OH formation rule
Example 8
The influence of the repeated use times of the three-metal carbon nanofiber loaded electro-Fenton cathode on the removal effect of enrofloxacin is as follows:
a two-electrode system was constructed using a Pt sheet as an anode and the cathode prepared in example 1 as a cathode, and the influence of the number of times of repeated use of the cathode on the removal rate of enrofloxacin was investigated under the conditions of pH of 3, applied current of 40mA, cycle time of 30min and continuous aeration in the vicinity of the cathode, as shown in Table 3. As can be seen from Table 3, the cathode repeatedly used for 5 times still has high catalytic activity, and the removal rate of 50mL of enrofloxacin with the concentration of 10mg/L is not obviously reduced within 30min, and is kept above 93%. After the cathode is continuously operated for five times, the cathode has lower metal ion leaching rates (Fe: 0.35mg/L, Co: 0.14mg/L and Zn: 0.82mg/L), which indicates that the cathode has excellent stability.
TABLE 3 reusability experiment of Fe/Co/Zn @ C-NCNFs-800-CF cathodes
Example 9
The influence of the three-metal carbon nanofiber loaded electro-Fenton cathode on the removal effect of enrofloxacin under different pH conditions:
a two-electrode system was constructed using a Pt sheet as an anode and the cathode prepared in example 1 as a cathode, and the removal rate of 50mL of 10mg/L enrofloxacin was determined for the cathode at pH 2 to 10 under the conditions of a current of 40mA, a reaction time of 120min and continuous aeration in the vicinity of the cathode, and the results are shown in Table 4. It can be seen that the removal rate of enrofloxacin is 100% when the pH is 2-3, and 90% when the pH is 4. However, when the pH was increased from 4 to 10, the removal rate of enrofloxacin rapidly decreased, probably because sufficient H was present under acidic conditions+Can promote H202The iron ions, the zinc ions and the cobalt ions loaded on the surface of the carbon nano-fiber activate H2O2More OH is generated to promote the degradation of enrofloxacin, and H is generated under neutral and alkaline conditions202The poor stability of the compound (A) leads to low degradation efficiency of the enrofloxacin under the condition, and in addition, the compound (A) is subjected to basic condition HO2And H202The reaction also results in H202And (4) consumption.
TABLE 4 Effect of pH on enrofloxacin removal
Example 10
The influence of the three-metal carbon nanofiber loaded electro-Fenton cathode on the removal effect of enrofloxacin under different time conditions of applied current:
a two-electrode system was constructed using a Pt sheet as an anode and the cathode prepared in example 1 as a cathode, and the removal rate of 50mL of 10mg/L enrofloxacin was determined as shown in Table 5 when the time for applying the current was 0 to 120min under the conditions of pH 3, current of 20mA and continuous aeration near the cathode. It can be seen that when electricity is appliedThe removal rate of enrofloxacin was 35% at a flow time of 5 min. After that, the removal rate of enrofloxacin was significantly increased with the increase of the time of applying the current, and the removal rate of enrofloxacin was 92% at the time of applying the current for 60 min. The increase of the current application time is effective for promoting H2O2The generation and the continuous generation of OH are beneficial to the removal of enrofloxacin.
TABLE 5 Effect of time of applied Current on enrofloxacin removal
The above-mentioned embodiments are preferred embodiments of the present invention, but the detailed description of the present invention is not limited to the above-mentioned embodiments, and other changes, modifications, simplifications, etc. made by those skilled in the art without departing from the spirit and principle of the present invention should be included in the scope of patent protection defined by the claims of the present invention.