Preparation method of copper-nickel ferrite carbon nanotube and application of copper-nickel ferrite carbon nanotube in activating persulfate to degrade active black

Abstract

The invention discloses a preparation method of a copper-nickel ferrite carbon nanotube and an application of the copper-nickel ferrite carbon nanotube in activating persulfate to degrade reactive black, and the preparation method comprises the following steps: by taking a hydroxyl carbon nanotube as a carrier, preparing a novel copper-nickel ferrite hydroxylated multi-walled carbon nanotube catalyst MWCNTs-OH / CuNiFe2O4 by using a coprecipitation method in a loading manner; the catalyst is used for activating peroxymonosulfate (PMS) and degrading active black RB5; results show that the degradation rate can finally reach 98.48% after the reaction time of 120 min under the room temperature condition, the peroxymonosulfate PMS is synergistically activated through the synergistic effect of the hydroxyl carbon nanotubes and the copper-nickel-iron metal, and efficient degradation of the active black RB5 can be completed under the simple condition; the invention provides a feasible strategy for efficiently degrading the active black, and has excellent popularization and application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst preparation, in particular to a preparation method of copper-nickel ferrite carbon nanotubes and application thereof in activated persulfate degradation of reactive black. BACKGROUND

[0002] More than 100,000 dyes and pigments are produced annually in the world, among which azo dyes with functional groups such as azo (-N=N-) and (-SO3Na, -OH, NH2) are used in the largest amount. Azo dyes have the functions of bright color, low adsorption to biomass, stable properties, high water solubility and difficult biodegradation. The discharge of wastewater containing dyes and their derivatives may affect human health and water environment safety. There are many treatment methods for dye removal, among which physical and chemical adsorption method, microbial treatment method, ion exchange technology and membrane separation technology have certain problems of unsatisfactory treatment efficiency, and may also cause pollution through other ways.

[0003] In recent years, advanced oxidation technology (AOP) based on sulfate radical (SO4 − ) is a popular method for treating stable pollutants in aqueous solution. Common persulfates include permonosulfate (PMS) and perdisulfate (PDS). PMS has an asymmetric molecular structure and is more easily activated, and has stronger organic pollutant mineralization ability, so it is an environmentally friendly treatment technology. Ultraviolet light, heat, ultrasonic wave, electrochemistry, cavitation, alkali, transition metal ions and carbon-based materials can all play an activating role. The metal oxide catalyst / PMS system can remove high-concentration pollutants in a short time under the conditions of lower PMS concentration, wide pH range and reduced catalyst input. The modification or modification of transition metals or metal oxides using porous structure carriers such as carbon-based materials, molecular sieves or MOFs can improve the dispersion and stability of metals, inhibit the hidden leaching of metals, and optimize the degradation capacity of the overall system. The new material has a stable structure and different activation mechanisms due to the modification of the material. Studies have shown that if the specific surface area of the block material is small, it cannot provide enough active sites for activation, thus limiting the degradation efficiency. Carbon nanotubes (CNTs) as a new type of carbon nanometer have uniform tubular structure, pore size less than 50 nm, large specific surface area, high electron, super elasticity, good chemical stability and other unique properties, and have been widely concerned in many fields such as electronic devices, hydrogen storage, new catalyst carriers, adsorption and separation of pollutants. By forming a heterogeneous catalyst with metal-based composite materials, non-metal-based composite materials and bio-based composite materials loaded on CNTs, especially a large number of experiments on developing bimetallic or multimetallic composite materials as metal oxides have been carried out to improve the activation performance of the catalyst to maximize the degradation of pollutants.

[0004] The application takes hydroxyl carbon nanotubes as a carrier, and a novel copper-nickel-iron oxide hydroxylized multi-walled carbon nanotube catalyst MWCNTs-OH / CuNiFe2O4 is prepared by using a coprecipitation method to load, the catalyst activates peroxymonosulfate PMS and carries out degradation of reactive black RB5; the results show that after a reaction time of 120 min under room temperature conditions, the degradation rate can finally reach 98.48 %, the hydroxyl carbon nanotube, the synergistic effect of copper-nickel-iron metal, the synergistic activation of peroxymonosulfate PMS, and the efficient degradation of reactive black RB5 under simple conditions can be realized; the application provides a feasible strategy for efficient degradation of reactive black, and has excellent popularization and application prospect. SUMMARY

[0005] The application aims to overcome the defects of the prior art, and provides a preparation method of copper-nickel-iron oxide carbon nanotubes and application thereof in activation of persulfate for degradation of reactive black, the preparation method is as follows: taking hydroxyl carbon nanotubes as a carrier, a novel copper-nickel-iron oxide hydroxylized multi-walled carbon nanotube catalyst MWCNTs-OH / CuNiFe2O4 is prepared by using a coprecipitation method to load, the catalyst activates peroxymonosulfate PMS and carries out degradation of reactive black RB5; the results show that after a reaction time of 120 min under room temperature conditions, the degradation rate can finally reach 98.48 %, the hydroxyl carbon nanotube, the synergistic effect of copper-nickel-iron metal, the synergistic activation of peroxymonosulfate PMS, and the efficient degradation of reactive black RB5 under simple conditions can be realized.

[0006] To achieve the above technical effects, the following technical scheme is adopted: A preparation method of copper-nickel-iron oxide carbon nanotubes, comprising the following steps: Step S1: coprecipitation loading of copper-nickel-iron Hydroxylized multi-walled carbon nanotubes MWCNTs-OH are mixed with ultrapure water under ultrasonic wave, then FeCl3·6H2O, CuCl2·2H2O and NiCl2·6H2O are added, stirring is uniformly carried out, a pH adjuster is used to adjust the pH value, and a mixture is obtained; the obtained mixture is heated, stirring is kept, the solid is separated by filtration, the solid is washed for multiple times, and the solid sample is dried at room temperature; Step S2: preparation of copper-nickel-iron oxide carbon nanotubes The solid sample obtained in step S1 is kept at high temperature and then fully ground, and a black powder-shaped MWCNTs-OH / CuNiFe2O4 catalyst is obtained, which is the copper-nickel-iron oxide carbon nanotube.

[0007] Further, the mass ratio of the hydroxylated multi-walled carbon nanotubes MWCNTs-OH, ultrapure water, FeCl3 6H2O, CuCl2 2H2O and NiCl2 6H2O in the step S1 is 0.875-1.75:100:0.5-1:0.25-0.5:0.125-0.25.

[0008] Further, the ultrasonic mixing time in the step S1 is 15 min.

[0009] Further, after adding FeCl3 6H2O, CuCl2 2H2O and NiCl2 6H2O in the step S1, the mixture is heated to 95-100 °C and stirred at 700 r·min -1 for 60 min.

[0010] Further, the pH regulator in the step S1 is NaOH with a concentration of 5 mol / L; the pH value is adjusted to 11-12.

[0011] Further, the mixture in the step S1 is heated to 95-100 °C and stirred at 700 r·min -1 for 4 h.

[0012] Further, the solid is separated by filtering with a 0.45 μm filter in the step S1; the solid sample is washed with ultrapure water.

[0013] Further, the solid sample obtained in the step S1 is placed in a muffle furnace in the step S2, and after being kept at 300 °C for 1 h, it is fully ground with an agate mortar.

[0014] A copper-nickel ferrite carbon nanotube prepared by any one of the above preparation methods.

[0015] Application of the copper-nickel ferrite carbon nanotube in activated persulfate degradation of active black.

[0016] The beneficial effects of the present application are: The application discloses a preparation method of copper-nickel ferrite carbon nanotubes and application of the copper-nickel ferrite carbon nanotubes in activated persulfate degradation of reactive black, and the preparation method is as follows: a novel copper-nickel ferrite hydroxylated multi-walled carbon nanotube catalyst MWCNTs-OH / CuNiFe2O4 is prepared by using hydroxyl carbon nanotubes as a carrier and by means of a co-precipitation method, the catalyst activates per monosulfate PMS and degrades reactive black RB5; results show that after a reaction time of 120 min at room temperature, the degradation rate can finally reach 98.48 %, the hydroxyl carbon nanotubes, the synergistic effect of copper-nickel iron metal, the synergistic activation of per monosulfate PMS, the hydroxyl carbon nanotubes, the copper-nickel iron metal and the PMS are indispensable, and the efficient degradation of the reactive black RB5 can be completed under simple conditions, and the degradation mechanism is clear; the application provides a feasible strategy for efficient degradation of the reactive black, and has excellent popularization and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description, and the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the provided drawings.

[0018] Figure 1 It is a standard curve of the RB5 solution in the embodiment of the present application; Figure 2 It is a scanning electron microscope (SEM) image of MWCNTs-OH in the embodiment of the present application; Figure 3 It is a scanning electron microscope (SEM) image of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:15) in the embodiment of the present application; Figure 4 It is a scanning electron microscope (SEM) image of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) in the embodiment of the present application; Figure 5 It is a scanning electron microscope (SEM) image of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:1) in the embodiment of the present application; Figure 6 It is a scanning electron microscope (SEM) image of MWCNTs-OH / CuNiFe2O4 (mass ratio 2:1) in the embodiment of the present application; Figure 7 It is a scanning electron microscope (SEM) image of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:2) in the embodiment of the present application; Figure 8Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH of the embodiment of the present application; Figure 9 Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) of the embodiment of the present application; Figure 10 Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) of the embodiment of the present application; Figure 11 Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) of the embodiment of the present application; Figure 12 Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) of the embodiment of the present application; Figure 13 Adsorption-desorption isotherm and pore size distribution (BET) diagram of MWCNTs-OH / CuNiFe2O4 (mass ratio 1:8) of the embodiment of the present application; Figure 14 X-ray diffraction (XRD) diagram of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 catalysts with different mass ratios of the embodiment of the present application; Figure 15 Fourier transform infrared spectrum (FTIR) diagram of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 catalysts with different mass ratios of the embodiment of the present application; Figure 16 Degradation efficiency diagram of different systems under the condition of PMS concentration of 2 mM·L -1 , catalyst dosage of 100 mg·L -1 , RB5 concentration of 50 mg·L -1 , temperature of 27 ℃, and initial pH = 7 of the embodiment of the present application; Figure 17 Degradation efficiency diagram of different PMS concentrations under the condition of MWCNTs-OH / CuNiFe2O4 catalyst dosage of 100 mg·L -1 , RB5 concentration of 50 mg·L -1 , temperature of 27 ℃, and initial pH = 7 of the embodiment of the present application; Figure 18 Degradation efficiency diagram of different PMS concentrations under the condition of PMS concentration of 2 mM·L -1 , RB5 concentration of 50 mg·L -1, degradation efficiency graph of different catalyst dosages under the condition of temperature 27 DEG C, initial pH = 7; Figure 19 PMS concentration of the embodiment of the application is 2 mM·L -1 MWCNTs-OH / CuNiFe2O4 catalyst dosage is 100 mg·L -1 , degradation efficiency graph of different RB5 concentrations under the condition of temperature 27 DEG C, initial pH = 7; Figure 20 PMS concentration of the embodiment of the application is 2 mM·L -1 MWCNTs-OH / CuNiFe2O4 catalyst dosage is 100 mg·L -1 RB5 concentration is 50 mg·L -1 , degradation efficiency graph of different temperatures under the condition of initial pH = 7; Figure 21 PMS concentration of the embodiment of the application is 2 mM·L -1 MWCNTs-OH / CuNiFe2O4 catalyst dosage is 100 mg·L -1 RB5 concentration is 50 mg·L -1 , degradation efficiency graph of different pH under the condition of temperature 27 DEG C; Figure 22 PMS concentration of the embodiment of the application is 2 mM·L -1 MWCNTs-OH / CuNiFe2O4 catalyst dosage is 100 mg·L -1 RB5 concentration is 50 mg·L -1 , degradation efficiency graph of coexisting ions in water under the condition of temperature 27 DEG C, initial pH = 7; Figure 23 RB5 ultraviolet / visible spectrum curve changing with time of the embodiment of the application; Figure 24 RB5 degradation process degradation curve of different free radical quenchers of the embodiment of the application; Figure 25 RB5 degradation process free radical generation and transfer process graph of the embodiment of the application; Figure 26 RB5 degradation basic process graph of the embodiment of the application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the application more clear and understandable, the application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described here are only used to explain the application, and are not used to limit the application.

[0020] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0021] It is also important to note that the terms "or" and "and" as used herein, shall each be interpreted as an inclusive and not an exclusive disjunction, unless otherwise indicated. As used herein, unless otherwise indicated, the use of the term "about" in relation to a value means that the value is within a range of ± 10% of the value.

[0022] Example 1: 1. Preparation of MWCNTs-OH / CuNiFe2O4 catalyst 1.1 Materials, reagents and experimental apparatus Hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) (Nanjing Xianfeng Nanometer Material Technology Co., Ltd., tube diameter 8-15 nm, length 500-2000 nm, purity > 95%, hydroxyl content 3.70 wt%), reactive black 5 (RB5) (Shanghai Maikelin Biochemical Technology Co., Ltd.), oxone (PMS) (Sanen Chemical Technology Co., Ltd.), ethanol, tert-butyl alcohol (National Pharmaceutical Group Chemical Reagent Co., Ltd.), potassium iodide (Hongyan Chemical Reagent Factory) and benzoquinone (Araldite Biochemical Technology Co., Ltd.). The experimental water is ultrapure water.

[0023] (1) Scanning electron microscope (SEM): The original appearance of MWCNTs-OH and the surface morphology of MWCNTs-OH / CuNiFe2O4 catalyst material were observed by using the SU8010 type scanning electron microscope of Hitachi Hi- tech Co., Ltd. A small amount of powder sample was fixed on the surface by using conductive glue, and then observed after gold spraying. The acceleration voltage during measurement was 15 kV, and the changes of the two materials were compared.

[0024] (2) Specific surface area and pore size analysis (BET): The pore size, pore volume and specific surface area of MWCNTs-OH / CuNiFe2O4 catalyst material were measured by using the ASAP 2460 type pore size analyzer of American Micromeritics Co., Ltd. About 0.15 g of dry sample was weighed before measurement, and then degassed at 200 ℃ for more than 2 h, and then the subsequent measurement was carried out.

[0025] (3) X-ray diffraction (XRD): XER-6100 X-ray diffractometer of Japan Shimadzu Co. was used to determine the composition of the MWCNTs-OH / CuNiFe2O4 catalyst material. When measuring, the parameters were set, the scanning rate was 2 ° / min, and the scanning range was 10-80 °.

[0026] (4) Fourier transform infrared spectroscopy (FTIR): TENSOR 27 Fourier transform infrared spectrometer of Germany bruker Co. was used to analyze the type of functional groups on the surface of the MWCNTs-OH / CuNiFe2O4 catalyst material. The scanning measurement was carried out under the condition that the resolution was 4 cm -1 , and the wavelength range was 400-4000 cm -1 .

[0027] 1.2 Preparation of catalyst 1.2.1 Preparation of MWCNTs-OH / CuNiFe2O4 catalyst Five different mass ratios of copper-nickel ferrite hydroxylated carbon nanotube (MWCNTs-OH / CuNiFe2O4) composites, 1:15, 1:8, 2:1, 1:1, and 1:2, were synthesized by co-precipitation method as catalysts. Taking the 1:1 mass ratio composite as an example (other mass ratios of copper-nickel ferrite hydroxylated carbon nanotubes are increased or decreased in proportion), the specific preparation method is as follows: 0.875 g of MWCNTs-OH was ultrasonically treated with 100 mL of ultrapure water for 15 min, followed by adding 0.500 g of FeCl3·6H2O, 0.250 g of CuCl2·2H2O, and 0.125 g of NiCl2·6H2O. The mixture was stirred at 700 r·min -1 for 60 min on a constant temperature magnetic stirrer. The pH value was adjusted to 11-12 using 5 M NaOH, the resulting mixture was heated to 95-100 °C, and continuously stirred at 700 r·min -1 for 4 h. The solid was separated by a 0.45 μm filter, washed with ultrapure water for several times, and the sample was dried at room temperature. To improve the stability and crystallinity of the sample, it was placed in a muffle furnace at 300 °C for 1 h and then fully ground with an agate mortar to obtain a black powder of MWCNTs-OH / CuNiFe2O4 catalyst, which was sealed and stored in a desiccator for standby.

[0028] 1.2.2 Preparation of control group MWCNTs-OH / NiFe2O4, MWCNTs-OH / CuFe2O4, MWCNTs-OH / CuNi2O4, MWCNTs-OH / Fe2O3, MWCNTs-OH / CuO, MWCNTs-OH / NiO, and MWCNTs / CuNiFe2O4 catalysts Similarly, the preparation conditions for the control group are as follows: Taking the preparation of a 1:1 mass ratio composite material as an example (catalysts of other mass ratios are increased or decreased proportionally), the preparation of MWCNTs-OH / NiFe2O4 requires the addition of 0.875 g MWCNTs-OH, 0.700 g FeCl3·6H2O, and 0.175 g NiCl2·6H2O, with the remaining preparation steps the same as in 1.2.1; the preparation of MWCNTs-OH / CuFe2O4 requires the addition of 0.875 g MWCNTs-OH, 0.583 g FeCl3·6H2O, and 0.292 g CuCl2·2H2O, with the remaining preparation steps the same as in 1.2.1; the preparation of MWCNTs-OH / CuNi2O4 requires the addition of 0.875 g MWCNTs-OH, 0.583 g FeCl3·6H2O, and 0.292 g CuCl2·2H2O, with the remaining preparation steps the same as in 1.2.1; the preparation of MWCNTs-OH / CuNi2O4 requires the addition of 0.875 g MWCNTs-OH, 0.583 g FeCl3·6H2O, and 0.292 g CuCl2·2H2O. The preparation steps are the same as in 1.2.1: 0.875 g MWCNTs-OH and 0.875 g FeCl3·6H2O are added to prepare MWCNTs-OH / Fe2O3; the remaining preparation steps are the same as in 1.2.1. Similarly, the preparation steps are the same as in 1.2.1: 0.875 g MWCNTs-OH and 0.875 g CuCl2·2H2O are added to prepare MWCNTs-OH / CuO; the remaining preparation steps are the same as in 1.2.1. Finally, the preparation steps are the same as in 1.2.1: 0.875 g MWCNTs-OH and 0.875 g CuCl2·2H2O are added to prepare MWCNTs-OH / NiO. To verify the superior performance of the support, MWCNTs were used instead of the support. The preparation of MWCNTs / CuNiFe2O4 required the addition of 0.875 g MWCNTs, 0.500 g FeCl3·6H2O, 0.250 g CuCl2·2H2O, and 0.125 g NiCl2·6H2O. The remaining preparation steps were the same as in 1.2.1.

[0029] 1.3 Plotting the standard curve of Reactive Black 5 (RB5) 1.3.1 Preparation of RB5 standard solution Weigh 0.1 g of RB5 into a beaker, add ultrapure water and stir until completely dissolved. Then, dilute to volume in a 100 mL volumetric flask to obtain a final concentration of 1 g·L⁻¹. -1 The RB5 standard solution should be stored in a dry environment for later use.

[0030] 1.3.2 Plotting the RB5 Standard Curve Six 50 mL cuvettes were prepared, and 2.5, 5.0, 7.5, 10.0, 15.0 mL of the prepared RB5 standard solution with a concentration of 100 mg·L-1were added to each of the cuvettes, respectively. Then, ultrapure water was added to make up to the mark of the cuvette. Finally, the concentrations of RB5 were 50, 100, 150, 200, and 300 mg·L-1, respectively. -1 The RB5 standard solution with a gradient concentration was prepared. The absorbance of the RB5 solution at different concentrations was measured at an absorption wavelength of 600 nm, and the standard curve of the RB5 solution was plotted, as shown in FIG. 2. Figure 1

[0031] 1.4 Degradation experiment under different catalytic systems 1.4.1 Catalytic degradation experiment process Thirteen groups of control experiments were set up, which were PMS, MWCNTs-OH, MWCNTs-OH / CuNiFe2O4, MWCNTs-OH / CuNiFe2O4 and PMS coexisting system, MWCNTs-OH and PMS coexisting system, MWCNTs-OH / NiFe2O4 and PMS coexisting system, MWCNTs-OH / CuFe2O4 and PMS coexisting system, MWCNTs-OH / CuNi2O4 and PMS coexisting system, MWCNTs-OH / Fe2O3 and PMS coexisting system, MWCNTs-OH / CuO and PMS coexisting system, MWCNTs-OH / NiO and PMS coexisting system, and MWCNTs / CuNiFe2O4 and PMS coexisting system. A certain amount of different carbon nanomaterials, PMS, and RB5 were weighed and added to 100 mL of ultrapure water. 5 mL of the initial solution was quickly removed using a sterile syringe, filtered using a filter head with a pore size of 0.45 μm, and the absorbance value was recorded. The sample was oscillated in a constant temperature oscillation box, and 5 mL of the sample was taken at 5, 15, 20, 40, 60, 80, 100, and 120 min, respectively. The absorbance was measured after filtering with the filter head, and the degradation rate was calculated. The concentration of reactive black 5 (RB5) was determined by ultraviolet / visible spectrophotometer during the removal process, and the ultraviolet absorption wavelength was set to 600 nm.

[0032] The degradation rate calculation formula (1) is as follows: (1) In the formula, C t is the RB5 concentration at time t; C0 is the RB5 concentration at the initial moment; t is the reaction time; η is the degradation rate; and the initial absorbance A measured in the experiment is 0.879.

[0033] 1.4.2 Degradation experiment of RB5 under different reaction systems and physicochemical factors ​To investigate the effects of temperature, initial pH, RB5 concentration, PMS concentration, MWCNTs-OH / CuNiFe2O4 catalyst dosage and coexisting ions in water on the degradation efficiency of RB5, the temperature conditions were set to 27, 35, 45 and 55 ℃, the pH conditions were set to 1, 3, 5 and 7, the RB5 concentration was set to 10, 25, 50, 100 and 200 mg·L -1 , the PMS concentration was set to 0.5, 1, 2, 4 and 6 mM·L -1 , the MWCNTs-OH / CuNiFe2O4 dosage was set to 25, 50, 100, 250 and 500 mg·L -1 , and sodium chloride, potassium dihydrogen phosphate and sodium bicarbonate were used as common ions in water for the experiment.

[0034] 1.4.3 Free radical quenching experiment The optimal catalyst and catalytic conditions were selected, and ETOH, TBA, BQ and KI were used for free radical quenching experiment to explore the role of different free radicals in the degradation process of RB5 and the degradation mechanism.

[0035] 1.5 Degradation effect analysis According to the kinetics of catalytic reaction, the catalytic kinetics curve was drawn, and the kinetic constants under each catalyst condition were calculated. The pseudo-first-order reaction kinetic constant is shown in formula (2), and the pseudo-second-order reaction kinetic constant is shown in formula (3).

[0036] (2) (3) In the formula: C t is the RB5 concentration at t time; C0 is the RB5 concentration at initial time; t is the reaction time; k1 is the pseudo-first-order reaction kinetic constant; k2 is the pseudo-second-order reaction kinetic constant; the initial absorbance A measured in the experiment is 0.879.

[0037] 2 Results and analysis 2.1 Material characterization 2.1.1 SEM analysis The surface morphology of MWCNTs-OH / CuNiFe2O4 was studied by scanning electron microscope (SEM), and the results are shown in Figure 2 to Figure 7 . Figure 2 It can be seen from Figure 3 , Figure 4 , Figure 5 , Figure 6 ,Figure 7 In MWCNTs-OH, the outer wall is coated with CuNiFe2O4 catalyst with a particle size of 100-200 nm, but in Figure 3 and Figure 4 In MWCNTs-OH, the outer wall is coated with CuNiFe2O4 catalyst with a particle size of 100-200 nm, but in

[0038] 2.1.2 BET analysis The N2 adsorption-desorption isotherms and pore size distribution of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 with different mass ratios were studied. The results are shown in Figure 8 to Figure 13 According to the IUPAC regulation, the adsorption isotherms of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 catalyst materials with different mass ratios belong to type IV. The N2 absorption amounts of desorption and adsorption are different under the same pressure, resulting in the trend of adsorption and desorption isotherms not completely consistent, producing hysteresis loops, Figure 8 、 Figure 9 、 Figure 10 and Figure 11 The hysteresis loop type of Figure 9 、 Figure 10 is H4, and the hysteresis loop type of

[0039] According to the BJH analysis model of BET, the specific surface area, pore volume and pore size of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 with different mass ratios are listed in Table 1. The specific surface area of MWCNTs-OH is 159.4476 m 2 ·g -1 , the pore volume is 0.779959 cm 3 ·g -1 , and the pore size is 18.6834 nm, showing a certain adsorption capacity. After loading CuNiFe2O4 with different mass ratios, the pore size and pore volume decreased, but the specific surface area increased. The increase of active sites enables the obtained composite catalyst to have the ability to degrade more pollutants.

[0040] Table 1 BET related parameters of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 with different mass ratios

[0041] 2.1.3 XRD Analysis The crystal structures of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 with different mass ratios were evaluated and analyzed using XRD. The results are as follows: Figure 14 As shown. MWCNTs-OH exhibits peaks at 2θ = 26.7 ° and 42.5 °, which is related to the graphite structure of the MWCNTs nanoparticles. The metal diffraction peaks of the ferrite may be related to Fe3O4, γ-Fe2O3, α-Fe2O3, and FeO(OH), with diffraction peaks at 2θ = 29.95°, 35.36°, 38.62°, 43.11°, 53.39°, 57.12°, and 62.59°, respectively. After loading CuNiFe2O4 onto the surface of MWCNTs-OH, its low-intensity diffraction peaks are similar to the XRD patterns of the metal diffraction peaks of the ferrite, indicating a well-formed spinel ferrite structure. Meanwhile, the sharp diffraction peaks of MWCNTs-OH are somewhat weakened after loading with CuNiFe2O4. According to the international standard card for CuFe2O4 (JCPDS 34-0425), Figure 14 The 2θ = 18.3 °, 30.2 °, 35.6 °, 43.2 °, 57.2 ° and 62.9 ° are basically consistent with the (220), (311), (400), (511) and (440) crystal planes of CuFe2O4, while according to the international standard card (JCPDS 10-0325) of NiFe2O4, Figure 14 The diffraction peak positions 2θ = 18.4 °, 30.3 °, 35.7 °, 37.3 °, 43.4 °, 53.8 °, and 71.5 ° correspond roughly to the (111), (220), (311), (222), (400), (422), and (620) crystal planes of NiFe₂O₄. Therefore, the XRD analysis results indicate that CuNiFe₂O₄ was successfully coated onto MWCNTs-OH.

[0042] 2.1.4 FTIR Analysis Fourier transform infrared spectra of MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 with different mass ratios are as follows: Figure 15 As shown. In the FTIR spectrum of MWCNTs-OH, at 3650 cm⁻¹ -1 The stretching vibration peak is inherent to the -OH group of the material. In the FTIR spectrum of MWCNTs-OH / CuNiFe2O4, at 600 cm⁻¹... -1A peak was also observed nearby, which was related to the stretching vibration caused by Fe-O-Fe bond, and was consistent with the spinel ferrite structure of the nanocatalyst. There were more stretching oscillation peaks near 2000~2500 cm -1 According to previous studies, the presence of C=C and C-O on the carbon nanotubes was indicated, and the presence of more chemical groups on the MWCNTs-OH / CuNiFe2O4 was beneficial to the production of the required substances in the catalytic reaction system.

[0043] 2.2 MWCNTs-OH / CuNiFe2O4 catalyst material and comparative group catalyst material catalytic performance 2.2.1 Catalytic kinetics model analysis results The catalytic kinetics model was used for analysis and comparison in this experiment, and the pseudo-first-order kinetic model and the pseudo-second-order kinetic model were selected, and the calculation formulas are shown in formulas (2) and (3). According to the kinetic fitting curve, the calculation results are shown in Table 2. In Table 2, the correlation coefficient R 2 of the pseudo-first-order kinetic model is higher, so the pseudo-first-order kinetic model is more suitable for explaining the difference in RB5 degradation efficiency under different systems. The pseudo-first-order kinetic rate constant shows that the reaction rate constant (K obs ) of MWCNTs-OH, MWCNTs-OH / CuNiFe2O4 and PMS system respectively is 0.000068, 0.00111, 0.00207 min -1 , while the system of MWCNTs-OH / CuNiFe2O4 with different mass ratios and PMS can improve K obs to 0.01762, 0.02204, 0.03488 min -1 , which also shows that the degradation performance of the latter is significantly improved, and the reaction rate constant (K obs ) of the control group catalyst material is almost unsatisfactory.

[0044] Table 2 Kinetic fitting parameters under different systems

[0045] 2.2.2 Catalytic performance of different catalytic systems Figure 16 Different systems show that the PMS concentration is 2 mM·L -1 , the mass ratio of MWCNTs-OH / CuNiFe2O4 catalyst dosage is 100 mg L -1 , and the RB5 concentration is 50 mg·L -1, temperature was 27 ℃, the initial pH was 7, and showed different effects on the degradation of RB5. In the MWCNTs-OH and MWCNTs-OH / CuNiFe2O4 system alone, the degradation rate was 7.82% and 12.5% respectively after 120 min of reaction, and the degradation efficiency was low. Based on the above BET data analysis, it is basically considered that the simple adsorption effect of the pore structure of MWCNTs-OH makes the concentration of RB5 decrease, but its adsorption capacity is limited, resulting in low degradation efficiency. In the PMS system alone, the degradation rate was only 4.06% after 120 min. The reason is that PMS is not easy to spontaneously generate a variety of active free radicals and degrade RB5 without catalyst. In the degradation system of MWCNTs-OH / CuNiFe2O4 catalyst and PMS with different mass ratios, the degradation efficiency of RB5 was increased to 87.92%, 92.92%, and 98.48%, respectively. At the same time, in the degradation system of MWCNTs-OH / NiFe2O4, MWCNTs-OH / CuFe2O4, MWCNTs-OH / CuNi2O4, MWCNTs-OH / Fe2O3, MWCNTs-OH / CuO, MWCNTs-OH / NiO catalyst and PMS, the degradation efficiency of RB5 was 48.10%, 43.77%, 38.12%, 36.12%, 32.96%, and 24.80%, respectively, which was significantly lower than that of the degradation system of MWCNTs-OH / CuNiFe2O4 catalyst and PMS. In the degradation system of MWCNTs / CuNiFe2O4 catalyst and PMS, the degradation efficiency was only 21.14%, which showed that MWCNTs-OH played a key role in the composite material. These results show that under the action of the catalyst, MWCNTs-OH / CuNiFe2O4 has the potential to activate PMS, which can activate PMS to generate a large number of free radicals, and different mass ratios of MWCNTs-OH / CuNiFe2O4 also have different catalytic degradation performance for RB5; also shows that hydroxylated multi-walled carbon nanotubes loaded with a variety of metal oxides can improve the catalytic degradation performance of RB5.

[0046] Based on the above analysis, the MWCNTs-OH / CuNiFe2O4(1:2) / PMS system was selected to study the effects of temperature, initial pH, RB5 concentration, PMS concentration, MWCNTs-OH / CuNiFe2O4 catalyst dosage, and coexisting ions in water on the degradation efficiency of RB5.

[0047] 2.3 Effects of various factors on the degradation efficiency of RB5 2.3.1 PMS concentration effect In the MWCNTs-OH / CuNiFe2O4 / PMS system, Figure 17 The effect of PMS dosage on RB5 removal efficiency was demonstrated. Figure 17 It can be seen that when the PMS concentration increases from 0.5 mM·L... -1 Increased to 6 mM·L -1 At the time, the highest removal efficiency was observed when the PMS concentration was 2 mM·L⁻¹ after 60 min of reaction. -1 The highest concentration reached 65.80%, with the slowest being a PMS concentration of 0.5 mM·L⁻¹. -1 The removal efficiency reached 44.57%. With prolonged reaction time, the highest removal efficiency was achieved at a PMS concentration of 4 mM·L⁻¹ after 100 min. -1 This indicates that more free radicals are generated and participate in the reaction under these conditions. It is also noted that the PMS concentration is 6 mM·L⁻¹. -1 The removal efficiency was not the fastest at any time point. The possible reason is that the free radicals generated by PMS in the research results undergo other reactions in the system, eventually producing free radicals with lower oxidation potentials. The process is shown below.

[0048] SO4 − · + HSO5 - →SO5 − · + HSO4 - ; ·OH + HSO5 - →OH − + HSO4 - . Furthermore, when the reaction time reached 120 min, the PMS dosage was reduced from 0.5 mM·L. -1 Increased to 4 mM·L -1 During the process, Figure 17 The kinetic rate constant K in the illustration obs The value ranges from 0.0079 min. -1 Increased to 0.0276 min -1 This also demonstrates that when the PMS concentration increases to a certain level, more SO4 is produced, which is conducive to the reaction. − · and ·OH. However, the amount of PMS was further increased to 6 mM·L. -1 At that time, K obs The value begins to decrease, indicating that the reaction is being hindered to some extent.

[0049] 2.3.2 Effect of MWCNTs-OH / CuNiFe2O4 catalyst dosage In the MWCNTs-OH / CuNiFe2O4 / PMS system, the effect of catalyst dosage on RB5 removal rate is as follows:Figure 18 As shown in the figure, when the catalyst concentration increased from 25 mg·L -1 to 500 mg·L -1 , the removal efficiency of RB5 increased from 16.87 % to 98.99 % within 60 min, while when the catalyst concentration was 500 mg·L -1 , the reaction could be considered as a complete removal state after 80 min. Figure 18 In the figure, the kinetic analysis results show that the degradation efficiency of RB5 also has the same trend, when the catalyst dosage increases from 25 mg·L -1 to 500 mg·L -1 , the K obs value increases rapidly from 0.0035 min -1 to 0.0766 min -1 after 120 min of reaction time. This can be explained that the more MWCNTs-OH / CuNiFe2O4 is used, the more active functional sites are provided for the adsorption of pollutants and the activation of PMS. In the reaction process, various active free radicals generated by the activation of PMS by metal ions may be related to the consumption of SO4 − ·and·OH, and the main reactions in this process are shown as follows.

[0050] SO4 − · + M 2+ →SO4 2− + M 3+ ; ·OH· + M 2+ →OH − + M 3+ .

[0051] 2.3.3 RB5 concentration influence In the MWCNTs-OH / CuNiFe2O4 / PMS system, it can be seen from the figure that as the initial concentration of RB5 increases, the degradation rate decreases significantly, and when the reaction time is 40 min, the removal efficiency of RB5 with a concentration of 10 mg·L -1 is 98.38 %, while the removal efficiency of RB5 with a concentration of 200 mg·L -1 is only 11.38 %. These results are also confirmed by the K obs value in the figure, and the K -1 value decreases from 0.1030 min -1 to 0.0024 min obs when the concentration of RB5 increases from 10 mg·L -1 to 200 mg·L -1 .-1 This may be the high concentration of pollutants, due to the activation of PMS catalyst to produce the number of free radicals, beyond the amount of pollutants can be degraded content.

[0052] 2.3.4 Temperature effect In the MWCNTs-OH / CuNiFe2O4 / PMS system, Figure 20 The effect of temperature on the catalytic performance of RB5 was studied. In the first 15 min of the reaction time, the removal efficiency of RB5 increased rapidly from 27.75% to 99.84% as the temperature increased from 27 ℃ to 55 ℃. As the temperature increased, the degradation efficiency was faster and the time to reach equilibrium was shorter. The results of the kinetic analysis confirmed that the effect of solution temperature on the degradation rate of RB5 was consistent with the above. The main reason is that in the case of high temperature, the O-O bond of the persulfate ion in PMS is destroyed by thermal decomposition, and more SO4 − · active groups.

[0053] 2.3.5 pH effect In the experiment of catalytic persulfate, the initial pH value is an important parameter, which affects the migration and conversion of the surface charge of the catalyst, and also has a great influence on the generation of electrons and transfer process of PMS, ultimately affecting the oxidation potential of active free radicals. And Figure 21 In the MWCNTs-OH / CuNiFe2O4 / PMS system with a pH range of 1-7, the removal efficiency of RB5 increased from 22.13% to 98.48% when the pH was from 1 to 7, which indicated that the removal efficiency was better under the condition closer to neutral. Under acidic conditions, the reaction was obviously inhibited. According to previous studies, the lower the pH, the more SO4 − · is generated, and the phenomenon of self-quenching of SO4 − · occurs, so the removal efficiency decreases.

[0054] 2.3.6 Effect of coexisting ions in water In the MWCNTs-OH / CuNiFe2O4 / PMS system, Figure 22 The differences in degradation efficiency of RB5 in the presence of different anions (Cl - , HCO3 - and H2PO4 - ) in the system were shown. The results showed that the kinetic rate constant K - was 0.0209, 0.2805 and 0.0013 min obs , respectively, when Cl -1 , HCO3 obs and H2PO4 -1 were present, which was lower than the degradation system without any anion Kobs 0.2790 min -1 There is a clear difference, Cl - The presence of Cl - does not have a significant effect on the degradation efficiency. The low variation in efficiency can be explained by the fact that Cl - reacts with ·OH and ·OH to form active chlorate radicals with a lower redox potential than the main radicals in the system, the high redox potential radicals compensate for the consumption of Cl - and SO4 - ·, and degrade the organic pollutants to intermediate species, CO2 and H2O. Their equations are shown in (5), (6), (7), (8), (9), (10). In solutions containing HCO3 - , the degradation efficiency increases rapidly, while H2PO4 - has a higher limiting effect on the degradation of RB5, this decrease in efficiency can also be related to the production of active species with low oxidation potential, the related processes are shown below.

[0055] ·OH + Cl - → ClOH - ; SO4 − · + Cl - → SO4 2- + ·Cl; H + + ClOH - → H2O + ·Cl; Cl - + ·Cl → ·Cl2 - ; ·Cl2 - + ·Cl2 - → Cl2 + 2Cl - ; Cl2 + H2O → HOCl + H + + Cl - ; HCO3 - + SO4 − · → ·HCO3 - + SO4 2- ; HCO3 - + ·OH → ·CO3 - + H2O; CO3 2- + SO4 − · → ·CO3 - + SO4 2- ; CO32- ·OH→·CO3 - + OH - . 2.4 RB5 in the MWCNTs-OH / CuNiFe2O4 / PMS system catalytic degradation mechanism 2.4.1 UV / visible spectrum change analysis Figure 23 RB5 dye UV / visible spectrum change analysis at different times. From the figure, it can be seen that RB5 dye has two absorption peaks in the wavelength range of 200-800 nm, at 310 nm and 600 nm, respectively, of which the peak at 600 nm is the chromophore group of RB5, which is mainly azo bond, and 310 nm corresponds to benzene ring, naphthalene ring. When the UV / visible spectrum change analysis of RB5 solution is determined, after 60 min, the two peak values are obviously reduced, and according to Figure 23 the color change in the degradation color change graph, it shows that there is an intermediate substance. When the degradation time is prolonged, the intensity of the absorption peak gradually decreases until it tends to be flat, and a blue shift phenomenon appears at the maximum absorption peak, indicating that there is electron transfer in the degradation process and the substance changes. In the degradation color change graph, it can also be clearly seen that the color of RB5 changes from dark blue to light red and then to colorless, indicating that the chromophore group is completely destroyed, and with the extension of time, the degraded RB5 no longer recolors, indicating that the SO4 - ·and·OH produced in the process have high efficiency in completely removing the chromophore group of azo dye and ideal mineralization degree.

[0056] 2.4.2 Free radical quenching experiment to explore the catalytic degradation mechanism ETOH, TBA, BQ, KI were used to quench the free radicals in the solution, and the change of active free radicals was studied by quenching experiment, in which tert-butyl alcohol (TBA) and ethanol (EtOH) are two common quenching agents. According to the existing research, the reaction kinetic rate of EtOH to·OH is 1.2-2.8×10 9 M -1 s -1 , and the reaction kinetic rate of SO4 - ·is 1.6-7.7×10 9 M -1 s -1 . The reaction kinetic rate of TBA to·OH is 3.8-7.6×108 M -1 s -1 , and the reaction kinetic rate of SO4 - ·is only 4-9.1×10 5 M -1 s-1 . Figure 24 It can be seen that in the MWCNTs-OH / CuNiFe2O4 / PMS system, when 10 mM·L -1 of TBA was added, the removal efficiency decreased from 98.48 % without quenching agent to 63.93 %. However, when 10 mM·L -1 of EtOH was added, the removal efficiency decreased significantly from 98.48 % to 67.84 %. The K obs of RB5 decreased from 0.0349 min -1 without quenching agent to 0.0085 min -1 with TBA and 0.0095 min -1 with EtOH, indicating that both ·OH and SO4 - · were free radicals that could catalyze the degradation of RB5.

[0057] In addition, 1 mM·L -1 of p-benzoquinone (BQ) was used as ·O 2- quenching agent, and the results showed that it had little effect on the degradation of RB5. However, 1 mM·L -1 of potassium iodide (KI) was used to quench the surface-bound free radicals, and the results showed that KI could effectively capture the active species generated on the surface of MWCNTs-OH / CuNiFe2O4, and the degradation rate decreased significantly, indicating that the activation of PMS occurred on the surface of the MWCNTs-OH / CuNiFe2O4 catalyst, and the inhibition of PMS activation had little effect, indicating that the surface of the heterogeneous catalyst was a suitable activation environment in the catalytic system.

[0058] 2.4.3 Degradation process and possible pathways As can be seen from Figure 16 , MWCNTs-OH / CuNiFe2O4 can remove part of RB5. The presence of PMS alone can convert some RB5 into different intermediates through reactions, but based on the results of this experiment, these intermediates still cause the solution to develop color. On the other hand, the reaction between HSO5 - and active metal sites such as Cu 2+ , Ni 2+ and Fe 2+ can produce active SO4 - · to degrade RB5, and the main equation is shown below, and the specific generation and transfer of free radicals are shown in Figure 25 .

[0059] Cu 2+ + HSO5 - →Cu 3+ + SO4− · + OH - ; Fe 2+ + HSO5 - →Fe 3+ + SO4 − · + OH - ; Ni 2+ + HSO5 - →Ni 3+ + SO4 − · + OH - ; Cu 3+ / Fe 3+ / Ni 3+ + HSO5 - →Cu 2+ / Fe 2+ / Ni 2+ +SO5 - · + H2O / H + ; SO4 − · + H2O→SO4 2- + ·OH + H + ; SO4 − · + OH - →SO4 2- + ·OH+ H + ; SO4 − · / OH + RB5→intermediates + CO2+ H2O. Based on the above results, comprehensive analysis obtained the mechanism of MWCNTs-OH / CuNiFe2O4 activating PMS, the principle is shown in Figure 26 From the way I, II and III can be seen, RB5 decomposition produces 1H-benzimidazole-2-acetamide, 4-chloro-benzenesulfonic acid hydrazide and 4-nitrophenanthrene, intermediates are catalytically oxidized to small molecular substances such as acetic acid, propanoic acid and sulfurous acid through a series of reactions.

[0060] 2.5 Comparison of the effects of different materials on the degradation of RB5 Table 3 shows the effect of different types of materials on the degradation of RB5 in simulated wastewater experiments. By comparing, we can see that inorganic non-metallic materials, metal materials and membrane materials all have certain degradation efficiency for RB5. However, due to the different properties of materials, the reaction conditions such as the required concentration of persulfate and the concentration of degradation materials also differ greatly. In this study, carbon nanomaterials were used to catalyze PMS, and the effect of degrading dye wastewater was good. Moreover, the concentration of PMS and catalyst added was small, and the impact on the environment in practical application was also small. Therefore, this study proposes a better method for treating dye wastewater containing RB5.

[0061] Table 3 Comparison of different materials for degrading RB5

[0062] References: [1] Wang Y, Wang J F, Li XL, et al. Catalytic degradation of azo dye reactive black 5 by Fe / zeolite[J]. Chinese Journal of Environmental Engineering, 2016, 10(8): 4177-4183. [2] Xiao T. Modified activated carbon fiber catalytic peroxymonosulfate degradation of reactive black 5 in water[D]. Qingdao: China Ocean University, 2015. [3] Li Z H. Preparation of CPVC composite nanofiltration membrane and its application in simulated RB5 dye wastewater treatment[D]. Shanghai: Donghua University, 2021. [4] Wang Y, Li C H, Gong W, et al. Degradation of reactive black 5 by Fe3O4 activated persulfate[J]. Environmental Pollution & Control, 2018, 40(8): 860-865. [5] Zhang P. Study on the degradation of reactive black 5 dye wastewater by iron-carbon micro-electrolysis filler activated persulfate[D]. Ganzhou: Jiangxi University of Science and Technology, 2020. In summary, the application discloses a preparation method of copper-nickel ferrite carbon nanotubes and application of the copper-nickel ferrite carbon nanotubes in activated persulfate degradation of reactive black, and the preparation method is as follows: a novel copper-nickel ferrite hydroxylated multi-walled carbon nanotube catalyst MWCNTs-OH / CuNiFe2O4 is prepared by using hydroxyl carbon nanotubes as a carrier and by using a coprecipitation method, the catalyst activates per monosulfate PMS and performs degradation of reactive black RB5; results show that after a reaction time of 120 min at room temperature, the degradation rate can finally reach 98.48 %, the hydroxyl carbon nanotubes, the synergistic effect of copper-nickel iron metal, the synergistic activation of per monosulfate PMS, the hydroxyl carbon nanotubes, the copper-nickel iron metal and the PMS are indispensable, efficient degradation of reactive black RB5 can be completed under simple conditions, the degradation mechanism is clear, SO4 - · and ·OH have high efficient synergistic complete removal of azo dye chromophore groups, and the mineralization degree is ideal; the application provides a feasible strategy for efficient degradation of reactive black, and has excellent popularization and application prospect.

[0063] Therefore, the scope of the application should be understood and recognized as covering all such other variations or modifications.

Claims

1. A method for preparing copper nickel ferrite carbon nanotubes, characterized by, The preparation method comprises the following steps: Step S1: co-precipitation of copper-nickel-iron loaded Hydroxylated multi-walled carbon nanotubes MWCNTs-OH are mixed with ultrapure water under ultrasonic, then FeCl3·6H2O, CuCl2·2H2O and NiCl2·6H2O are added, and stirred uniformly, and a pH regulator is used to adjust the pH value to obtain a mixture; the obtained mixture is heated and kept under constant stirring, the solid is separated by filtration, the solid is washed for several times, and the solid sample is dried at room temperature; Step S2: preparation of copper-nickel-iron oxide carbon nanotubes The solid sample obtained in step S1 is kept at high temperature and then fully ground to obtain black powder MWCNTs-OH / CuNiFe2O4 catalyst, which is the copper-nickel-iron oxide carbon nanotubes.

2. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, In step S1, the mass ratio of hydroxylated multi-walled carbon nanotubes MWCNTs-OH, ultrapure water, FeCl3·6H2O, CuCl2·2H2O and NiCl2·6H2O is 0.875-1.75:100:0.5-1:0.25-0.5:0.125-0.

25.

3. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, In step S1, the ultrasonic mixing time is 15 min.

4. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, The step S1 adds FeCl3·6H2O, CuCl2·2H2O, NiCl2·6H2O, and then 700 r·min -1 Stirring for 60 min.

5. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, In step S1, the pH regulator is NaOH with a concentration of 5 mol / L; the pH value is adjusted to 11-12.

6. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, The mixture in step S1 is heated to 95-100 °C, and stirred at 700 r·min -1 Constant stirring is maintained for 4 h.

7. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, In step S1, the solid is separated by filtration with a 0.45 μm filter; and the solid sample is washed with ultrapure water.

8. The method for preparing copper-nickel ferrite carbon nanotubes as described in claim 1, characterized in that, In step S2, the solid sample obtained in step S1 is placed in a muffle furnace, kept at 300 °C for 1 h, and then fully ground with an agate mortar.

9. A copper nickel ferrite carbon nanotube, characterized by, The copper-nickel-iron oxide carbon nanotubes are prepared by any one of the preparation methods in claims 1-8.

10. Use of copper nickel ferrite carbon nanotubes, characterized in that, The application of the copper-nickel-iron oxide carbon nanotubes in activated persulfate degradation of reactive black.

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