Cobalt-doped gallium oxide nanorod catalyst as well as preparation method and application thereof

Abstract

The invention discloses a cobalt-doped gallium oxide nanorod catalyst and a preparation method and application thereof.The preparation method of the cobalt-doped gallium oxide nanorod catalyst comprises the steps that a gallium source, a cobalt source, a surfactant and water are mixed to be uniform, the pH is adjusted to be 7.0-8.0 through an alkaline solution, heat preservation is conducted for 7.5-8 h at the temperature of 135-140 DEG C, the mixture is cooled to the room temperature, centrifugation, washing and drying are conducted, and the cobalt-doped gallium oxide nanorod catalyst is obtained. A cobalt-doped gallium oxide nanorod catalyst precursor is obtained; and in an air atmosphere, calcining the cobalt-doped gallium oxide nanorod catalyst precursor at 480-520 DEG C for 2-2.2 h to obtain the cobalt-doped gallium oxide nanorod catalyst. The PMS activated by the cobalt-doped gallium oxide nanorod catalyst has the capability of degrading micro-plastics in a water body.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and specifically relates to a cobalt-doped gallium oxide nanorod catalyst, its preparation method and application. Background Art

[0002] With the acceleration of industrialization and urbanization, the problem of water resource shortage has become increasingly severe. At the same time, a large number of chemical substances and pollutants emitted by human activities continue to enter the water environment, further exacerbating the risk of water pollution. On March 30, 2022, the Ministry of Ecology and Environment clearly included four types of pollutants widely concerned internationally - persistent organic pollutants (POPs), endocrine disruptors (EDCs), antibiotic pollutants and microplastics - into the scope of "new pollutants" control in a press conference. New pollutants generally have persistence, bioaccumulation and potential toxicity, and the monitoring means and treatment technologies of traditional sewage treatment plants are difficult to effectively remove them, resulting in an increasingly prominent threat to the ecological system and human health.

[0003] Currently, how to efficiently remove or transform new pollutants in wastewater has become the core task in the environmental field to avoid their entry into the receiving water body and cause secondary pollution. Traditional wastewater treatment technologies (such as adsorption, precipitation and ultrafiltration, etc.) mainly achieve pollutant separation through physical interception or phase transfer, but cannot completely convert them into harmless substances; while biological treatment technologies are severely limited due to the biological recalcitrance and low concentration characteristics of new pollutants. In this context, advanced oxidation processes (AOPs) are regarded as an effective solution for the advanced treatment of new pollutants because they can achieve the efficient mineralization of pollutants through reactive oxygen species (ROS).

[0004] In recent years, the advanced oxidation system based on peroxymonosulfate (PMS) has attracted much attention due to its unique oxidation mechanism. After activation, PMS can generate highly reactive free radicals such as sulfate radicals (SO4· - ), hydroxyl radicals (·OH), etc., as well as singlet oxygen ( 1 O2) with selective oxidation ability and metal-oxygen high-valence species, which can rapidly degrade refractory pollutants in a wide pH range and have advantages such as high system stability and low risk of secondary pollution. However, the oxidation ability of PMS itself is limited, and the O-O bond in its molecular structure has a relatively high dissociation energy (~377 kJ / mol), which leads to a low direct degradation efficiency. It is necessary to trigger a chain reaction by means of external energy input (such as heat, ultraviolet light, ultrasonic wave) or catalyst activation. Among them, heterogeneous catalytic activation in the way of catalyst activation has become a research hotspot due to its low energy consumption and strong recyclability, but the catalysts commonly used in existing heterogeneous catalytic activation generally face problems such as low catalytic activity and metal ion leaching. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a cobalt-doped gallium oxide nanorod catalyst.

[0006] Another purpose of the present invention is to provide a preparation method of a cobalt-doped gallium oxide nanorod catalyst. By doping Co into Ga2O3, the original charge symmetry of Ga2O3 is broken, thereby significantly improving the performance of the cobalt-doped gallium oxide nanorod catalyst in activating PMS to degrade pollutants.

[0007] Another purpose of the present invention is to provide the application of the above cobalt-doped gallium oxide nanocatalyst in removing pollutants.

[0008] The purpose of the present invention is achieved by the following technical solutions.

[0009] A cobalt-doped gallium oxide nanorod catalyst, which is Co-doped gallium oxide, and Co atoms are doped into the Ga2O3 lattice and replace some Ga atoms.

[0010] A preparation method of a cobalt-doped gallium oxide nanorod catalyst includes the following steps:

[0011] Step 1: Mix a gallium source, a cobalt source, a surfactant and water until uniform, adjust the pH to 7.0 - 8.0 with an alkaline solution, keep warm at 135 - 140 °C for 7.5 - 8 h, cool to room temperature, centrifuge, wash, and dry to obtain a precursor of the cobalt-doped gallium oxide nanorod catalyst. Among them, by the number of moles, the ratio of gallium in the gallium source to cobalt in the cobalt source is 15:(0.15 - 0.75);

[0012] In step 1, preferably, by the number of moles, the ratio of gallium in the gallium source to cobalt in the cobalt source is 15:(0.4 - 0.5).

[0013] In step 1, the gallium source is gallium nitrate hydrate, and the cobalt source is cobalt nitrate hexahydrate.

[0014] In step 1, the surfactant is sodium dodecylbenzenesulfonate.

[0015] In step 1, the ratio of the number of moles of gallium in the gallium source, the number of moles of the surfactant, and the volume fraction of water is 15:3:(55 - 65). The unit of the number of moles is mmol, and the unit of the volume fraction is mL.

[0016] In step 1, mix the gallium source, the cobalt source, the surfactant and water, and stir until uniform at room temperature.

[0017] In step 1, mix the gallium source, the surfactant and water, stir at room temperature for 4 - 6 min, add the cobalt source, and then stir at room temperature for 4 - 6 min.

[0018] In step 1, the alkaline solution is an aqueous NaOH solution, and the concentration of NaOH in the aqueous NaOH solution is 1.5 mol / L.

[0019] In step 1, the washing is carried out with water and absolute ethanol.

[0020] In step 1, the drying temperature is 60 - 80 °C, and the drying time is 8 - 12 h.

[0021] In step 1, the washing includes: centrifuging with water and absolute ethanol successively at a rotation speed of 8000 - 10000 r / min for at least three times each, and the centrifugation time for each time is 3 - 5 min.

[0022] Step 2, in an air atmosphere, calcine the cobalt-doped gallium oxide nanorod catalyst precursor at 480 - 520 °C for 2 - 2.2 h to obtain the cobalt-doped gallium oxide nanorod catalyst.

[0023] In step 2, the heating rate to 480 - 520 °C is 4 - 6 °C / min.

[0024] Application of the above cobalt-doped gallium oxide nanorod catalyst in removing pollutants.

[0025] In the above technical solution, the pollutants include: antibiotic pollutants and / or microplastics.

[0026] In the above technical solution, the antibiotic pollutants include: one or a mixture of more than one of tetracycline (TC), doxycycline hydrochloride (DOXH), ofloxacin (OFL), ciprofloxacin (CIP), and sulfamethoxazole (SMX).

[0027] In the above technical solution, the microplastics include: one or a mixture of more than one of PET, PPO, and PVC.

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

[0029] 1. The removal rate of the cobalt-doped gallium oxide nanorod catalyst of the present invention for tetracycline reaches 100% at 15 min, and the first-order kinetic constant of the cobalt-doped gallium oxide nanorod catalyst is increased by 30.7 times compared with the gallium oxide catalyst.

[0030] 2. The cobalt-doped gallium oxide nanorod catalyst of the present invention has strong anti-interference ability and has stable degradation performance under different interfering chemical substances and different interfering gases.

[0031] 3. The cobalt-doped gallium oxide nanorod catalyst of the present invention has excellent removal effects on various common antibiotic pollutants, and has good degradation performance and universality for actual sewage treatment at the same time.

[0032] 4. The cobalt-doped gallium oxide nanorod catalyst of the present invention has high stability and good structural stability and low metal ion leakage during the efficient activation of PMS.

[0033] 5. The cobalt-doped gallium oxide nanorod catalyst of the present invention can degrade microplastics in water by activating PMS. Description of the Drawings

[0034] Figure 1 a in is the TEM image of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 b in is the EDS elemental mapping spectrum of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 c in is the high-angle annular dark-field image (HAADF-STEM) of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 d in is Figure 1 the line intensity distribution diagram of the rectangles formed by X1Y1 and X2Y2 in c in ;

[0035] Figure 2 is the X-ray diffraction pattern, where Figure 2 a in and Figure 2 b in are the X-ray diffraction patterns of the gallium oxide (Ga2O3) catalyst prepared in Comparative Example 1 and the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, respectively;

[0036] Figure 3 a in is C t / C0 at T min when degrading pollutants with the catalysts in Comparative Examples 1-3 and Example 3 as the catalysts in the control group and the experimental group, Figure 3 b in is the reaction rate constant when degrading pollutants with the catalysts in Comparative Example 1 and Example 3 as the catalysts in the control group and the experimental group, respectively;

[0037] Figure 4 is C t / C0 at T min when degrading pollutants with the catalysts in Examples 1-5 as the catalysts in the experimental group;

[0038] Figure 5 is the removal rate of tetracycline by the cobalt-doped gallium oxide nanorod catalyst in Example 6;

[0039] Figure 6 is the removal rate of different types of pollutants by the cobalt-doped gallium oxide nanorod catalyst in Example 7;

[0040] Figure 7 is the Co 2+ leakage amount during the removal of tetracycline by activating PMS with the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3;

[0041] Figure 8 It is the total organic carbon (TOC) concentration graph in Example 10;

[0042] Figure 9 It is the laser infrared test result graph in Example 10;

[0043] Figure 10 It is the SEM image of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3;

[0044] Figure 11 It is the result of the quenching experiment in Example 9. Detailed implementation manners

[0045] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0046] The raw material information is as follows:

[0047]

[0048]

[0049]

[0050] The instrument information is as follows:

[0051] Instrument Model Manufacturer Electric Thermostatic Drying Oven 101-3A Shanghai Shengke Instrument Equipment Co., Ltd. Bench-top High-speed Centrifuge TG16-WS Hunan Xiangyi Centrifuge Company Intelligent Magnetic Stirrer ZNCL-GS Zhengzhou Huate Instrument Equipment Co., Ltd. Muffle Furnace KSL-1100X-S Hefei Kejing Materials Technology Co., Ltd. Leici pH Meter PHS-2F Shanghai Precision Scientific Instrument Co., Ltd. UV-Vis Spectrophotometer U-3900H Hitachi, Ltd. (Japan) Total Organic Carbon (TOC) Analyzer TOC-L CPN Shimadzu Corporation (Japan) X-ray Diffractometer Max2200PC Rigaku Corporation (Japan) Inductively Coupled Plasma Mass Spectrometer Elan drc-e PerkinElmer, Inc. (USA) Transmission Electron Microscope JEM-2100F JEOL Ltd. (Japan) Condenser Spherical Aberration Corrected Transmission Electron Microscope JEM-ARM200F JEOL Ltd. (Japan)

[0052] The PMS used in the following examples is specifically potassium peroxymonosulfate.

[0053] Examples 1-4

[0054] A preparation method of a cobalt-doped gallium oxide nanorod catalyst includes the following steps:

[0055] Step 1: Mix a gallium source, a surfactant, and deionized water, stir at a speed of 400 r / min at room temperature for 5 min, add a cobalt source, then stir at a speed of 400 r / min at room temperature for 5 min. Subsequently, adjust the pH to 7.5 ± 0.5 using a 1.5 mol / L aqueous NaOH solution, transfer it to a stainless-steel autoclave with a Teflon liner, keep it at 140 °C for 8 h, cool it to room temperature, centrifuge to collect the reaction product, wash it (centrifuge three times successively at a speed of 8000 r / min with water and absolute ethanol respectively, and the centrifugation time for each time is 3 min), and dry it in a vacuum drying oven at 60 °C for 8 h to obtain a cobalt-doped gallium oxide nanorod catalyst precursor. Among them, by the number of moles, the ratio of gallium in the gallium source to cobalt in the cobalt source is W, and the ratio of the number of moles of gallium in the gallium source, the number of moles of the surfactant, and the volume fraction of deionized water is 15:3:60. The unit of the number of moles is mmol, and the unit of the volume fraction is mL. The gallium source is gallium nitrate hydrate (255.74 (anhydrous basis) (MW)), the cobalt source is cobalt nitrate hexahydrate, and the surfactant is sodium dodecylbenzenesulfonate;

[0056] Step 2: Manually grind the cobalt-doped gallium oxide nanorod catalyst precursor in an agate mortar for 3 min to powder, transfer it to a muffle furnace, and in an air atmosphere, heat it to 500 °C at a rate of 5 °C / min and calcine it at 500 °C for 2 h to obtain a cobalt-doped gallium oxide nanorod catalyst.

[0057] W is shown in Table 1.

[0058] Table 1

[0059] Cobalt-doped Gallium Oxide Nanorod Catalyst W Example 1 15：0.15 Example 2 15：0.3 Example 3 15：0.45 Example 4 15：0.6 Example 5 15：0.75

[0060] Comparative Example 1

[0061] A preparation method of a gallium oxide (Ga2O3) catalyst is basically the same as that of Example 1, except that: in Comparative Example 1, no cobalt source is added.

[0062] Comparative Example 2

[0063] A preparation method of an iron-doped gallium oxide catalyst is basically the same as that of Example 3, except that: the "cobalt source" is replaced with an "iron source". The iron source is iron nitrate nonahydrate.

[0064] Comparative Example 3

[0065] A preparation method of a copper-doped gallium oxide catalyst is basically the same as that of Example 3, except that: the "cobalt source" is replaced with a "copper source". The copper source is copper nitrate trihydrate.

[0066] The morphology, crystal structure and element distribution of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 were characterized by transmission electron microscopy (TEM) and condenser spherical aberration corrected transmission electron microscopy (AC-TEM). Figure 1 As shown, Figure 1 a is the TEM of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 b is the EDS element mapping spectrum of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 c is a high-angle annular dark field image (HAADF-STEM) of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, Figure 1 The d is Figure 1 Line intensity distribution diagram of the rectangle composed of X1Y1 and the rectangle composed of X2Y2 in c. Figure 1 a and Figure 1 From b, it can be seen that the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 presents a good rod-like morphology, and the doped Co is evenly distributed in the cobalt-doped gallium oxide nanorod catalyst; Figure 1 It can be seen from the figure that the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 has clear lattice fringes and regular atomic arrangement. Figure 1 The lattice spacings of 0.19 nm and 0.25 nm in c correspond to the 202 and 110 planes of Ga2O3 (PDF#43-1013), respectively. With the Co atom as the center, line scanning energy spectrum analysis was performed along the X1Y1 and X2Y2 directions (the intersection of the rectangle formed by X1Y1 and the rectangle formed by X2Y2 is the Co atom, and the other atoms are Ga atoms). Figure 1 Line intensity distribution diagram of d, Figure 1 The d contains both Co atoms and Ga atoms (the higher intensity is Ga atoms, and the lower intensity is Co atoms), which indicates that Co atoms are successfully doped into the Ga2O3 lattice and replace part of the Ga atoms.

[0067] Figure 2 is the X-ray diffraction pattern, where Figure 2 a and Figure 2 b are the X-ray diffraction patterns of the gallium oxide (Ga2O3) catalyst prepared in Comparative Example 1 and the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, respectively. Figure 2In it, "Raw data" represents the original test data, "Calculated line" represents the calculated curve obtained from the "Raw data" (obtained by building, simulating, fitting, and optimizing using the original test data with GSAS software), "Bragg positions" represents the Bragg lattice, and "Difference" represents the difference curve (the difference curve is used to represent the difference between the "Raw data" and the "Calculated line"). Figure 2 a of Figure 2 and b of Figure 2 a of Figure 2 and b of show similar characteristic peak spectra. The Bragg diffraction peaks of Comparative Example 1 and Example 3 are the same as the peak positions of the proven trigonal crystal structure Ga2O3 (R-3c, JCPDS: 43-1013). At the same time, to further explore the structures of the cobalt-doped gallium oxide nanorod catalyst and the gallium oxide (Ga2O3) catalyst, a of

[0068] Figure 10 and b of Figure 10 were respectively subjected to Rietveld refinement of XRD. The results of the Rietveld refinement of XRD showed that the unit cell volume of the cobalt-doped gallium oxide nanorod catalyst Figure 1 is smaller than that of the gallium oxide (Ga2O3) catalyst

[0069] Example 5

[0070] Degradation experiment:

[0071] Experimental group: 20 mg of the catalyst and 50 mL of the pollutant solution were placed in a 100 mL beaker. Under natural light conditions, at 25 °C, it was stirred at a speed of 400 r / min for 30 min to reach the adsorption / desorption equilibrium. Then 20 mg of PMS was added for activation to obtain the reaction solution, and it was continuously stirred at a speed of 400 r / min. At the T-th minute after adding PMS, 3 mL of the reaction solution was taken, and the reaction solution was filtered through a 0.22 μm filter membrane to remove suspended matter to obtain the test solution. The absorbance of the test solution was measured with a UV-visible spectrophotometer as the concentration of the pollutant, denoted as C. T minutes were 0 min, 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min respectively. When T min = 0 min, C was C0. When T min = 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min, C was C t , and the degradation rate (removal rate) = (1 - (Ct / C0)) * 100%. Among them, the catalyst was one of the cobalt-doped gallium oxide nanorod catalysts prepared in Examples 1 to 5, the gallium oxide (Ga2O3) catalyst prepared in Comparative Example 1, the iron-doped gallium oxide catalyst prepared in Comparative Example 2, and the copper-doped gallium oxide catalyst prepared in Comparative Example 3. The pollutant solution was a mixture of the pollutant and water. The pollutant was tetracycline (an antibiotic pollutant). The concentration of the pollutant in the pollutant solution was 20 mg / L, and the pH of the pollutant solution was 7.0.

[0072] Control group: It was basically the same as the "experimental group", except that the catalyst was not added in the control group.

[0073] The results of the experimental group and the control group in degrading the antibiotic pollutant (tetracycline) are as Figure 3 and Figure 4 shown. Figure 3 For a in Figure 3 , it was the C / C0 at T min when the control group (in "PMS" of a in t ) and the experimental group used the catalysts of Comparative Examples 1 to 3 and Example 3 respectively to degrade the pollutant. Figure 3 For b in Figure 3 , it was the first-order kinetic constant when the control group (in "PMS" of b in Figure 4 ) and the experimental group used the catalysts of Comparative Example 1 and Example 3 respectively to degrade the pollutant. t / C0 was the C / C0 at T min when the experimental group used the catalysts of Examples 1 to 5 respectively to degrade the pollutant.

[0074] From Figure 3As can be seen from a of Figure 3 As can be seen from b, the first-order kinetic constant of tetracycline degradation by the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 is 30.7 times that of Comparative Example 1. The method for calculating the first-order kinetic constant refers to Zhu, Z.-S. et al. Multidimensional engineering of single-atom cobalt catalysts for ultrafast fenton-like reactions. Nat Water (2025) doi:10.1038 / s44221-024-00382-8.

[0075] From Example 1, Example 2, Example 3, Example 4 to Example 5, the doping amount of Co is increasing. As Figure 4 can be seen, in Examples 1-3, with the increase of the doping amount of Co, the degradation effect of the cobalt-doped gallium oxide nanorod catalyst on tetracycline is gradually enhanced. From Example 3 to Example 4 and then to Example 5, with the increase of the doping amount of Co, its degradation effect on tetracycline no longer increases and even decreases slightly. The cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 has the best degradation effect on pollutants, and its degradation rate of tetracycline reaches 100% at 15 min.

[0076] Example 6

[0077] To further explore the stability and anti-interference ability of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, the following interference experimental groups were set up:

[0078] The first interference experimental group: 20 mg of catalyst, interfering chemical substances, and 50 mL of pollutant solution were placed in a 100 mL beaker. Under natural light conditions, it was stirred at a speed of 400 r / min at 25 °C for 30 min to achieve adsorption / desorption equilibrium. Then, 20 mg of PMS was added for activation to obtain a reaction solution, which was continuously stirred at a speed of 400 r / min. At the 15th minute after adding PMS, 3 mL of the reaction solution was taken, and the reaction solution was filtered through a 0.22 μm filter membrane to remove suspended solids, obtaining a test solution. The absorbance of the test solution was measured with a UV-visible spectrophotometer as the concentration of the pollutant. Among them, the interfering chemical substances were one of NaCl, Na2SO4, NaNO3, NaHCO3, NaH2PO4, and humic acid (HA), and the concentration of the interfering chemical substance in the reaction solution was 5 mmol / L.

[0079] The second interference experimental group: 20 mg of catalyst and 50 mL of pollutant solution were placed in a 100 mL beaker. Interfering gas was continuously introduced into the pollutant solution. At the same time, under natural light conditions, it was stirred at a speed of 400 r / min at 25 °C for 30 min to achieve adsorption / desorption equilibrium. Then, 20 mg of PMS was added for activation to obtain a reaction solution, which was continuously stirred at a speed of 400 r / min. At the 15th minute after adding PMS, 3 mL of the reaction solution was taken, and the reaction solution was filtered through a 0.22 μm filter membrane to remove suspended solids, obtaining a test solution. The absorbance of the test solution was measured with a UV-visible spectrophotometer as the concentration of the pollutant. Among them, the interfering gas was one of air, O2, and N2, and the flow rate of the introduced interfering gas was 500 sccm.

[0080] In the test of Example 6, the catalyst was the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, and the pollutant solution was the same as that in Example 5.

[0081] Using the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 as the catalyst to degrade pollutants in the experimental group of Example 5 as a control ( Figure 5 “control”), compared with the results of the first interference experimental group and the second interference experimental group in degrading pollutants, the results are as Figure 5 shown. It can be Figure 5 seen that the interfering chemical substances and interfering gases have no significant effect on the removal rate of pollutants (tetracycline). The cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 is little affected by common environmental matrices and gas atmospheres in water, and has good stability and anti-interference ability.

[0082] Example 7

[0083] Perform the universality verification of the cobalt-doped gallium oxide nanorod catalyst, specifically as follows: Place 20 mg of the catalyst and 50 mL of the pollutant solution in a 100 mL beaker, and under natural light conditions, stir at a speed of 400 r / min at 25 °C for 30 min to reach the adsorption / desorption equilibrium. Then add 20 mg of PMS for activation to obtain the reaction solution, and continue to stir at a speed of 400 r / min. At the Tth minute (Tmin = 10 min or 15 min) after adding PMS, take 3 mL of the reaction solution, filter the reaction solution through a 0.22 μm filter membrane to remove suspended matter to obtain the test solution, and measure the absorbance of the test solution with a UV-visible spectrophotometer. Among them, the catalyst is the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, the pollutant solution is a mixture of the pollutant and water, and the pollutant (antibiotic pollutant) is one of tetracycline (TC), doxycycline hydrochloride (DOXH), ofloxacin (OFL), ciprofloxacin (CIP), and sulfamethoxazole (SMX), and the concentration of the pollutant in the pollutant solution is 10 mg / L.

[0084] The removal rates of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 for each pollutant are as Figure 6 shown. From Figure 6 it can be seen that the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 has good degradation performance for activating PMS for various types of pollutants. The removal rates of these five pollutants at 15 min are all above 90%, indicating that the cobalt-doped gallium oxide nanorod catalyst has good universality in removing antibiotics in water.

[0085] Example 8

[0086] Place 20 mg of the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 and 50 mL of the pollutant solution in a 100 mL beaker, and under natural light conditions, stir at a speed of 400 r / min at 25 °C for 30 min to reach the adsorption / desorption equilibrium. Then add 20 mg of PMS for activation to obtain the reaction solution, and continue to stir at a speed of 400 r / min. At the 0th min, 5th min, 10th min, or 20th min after adding PMS, take 2 mL of the reaction solution and use an inductively coupled plasma mass spectrometer (ICP-MS) to measure the metal ion concentration in the reaction solution at the 0th min, 5th min, 10th min, and 20th min respectively. The test results are as Figure 7 shown. From Figure 7 it can be seen that the Co 2+ concentration in the reaction solution at the 20th min is 0.0865 mg / L, which is much lower than the 1 mg / L specified in the "Emission Standard of Pollutants for Copper, Nickel, and Cobalt Industries" (GB25467-2010). This shows that the cobalt-doped gallium oxide nanorod catalyst of the present invention has high structural stability and environmental friendliness.

[0087] Example 9

[0088] Quenching experiment: It is basically the same as the "experimental group" in Example 5, except that: while adding 20 mg of PMS, a quenching agent is added (the concentration of the quenching agent in the reaction solution after adding the quenching agent is 20 mmol / L). Among them, the catalyst is the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, and the quenching agent is methanol (used to quench ·OH and SO4· - ), furfuryl alcohol (used to quench 1 O2), tert-butanol (used to quench ·OH), and SOD (superoxide dismutase, used to quench ·O2 - ). The results of the quenching experiment are as Figure 11 shown.

[0089] From Figure 11 it can be seen that ( Figure 11 in which "Control" represents C t / C0) in the "experimental group" of Example 5 with the catalyst of Example 3, furfuryl alcohol has the most obvious inhibitory effect on the activation of PMS by the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3 to degrade pollutants, indicating that 1 O2 is the main active species in this catalytic system, and at the same time, there is a small amount of SO4· - in the catalytic system.

[0090] Example 10

[0091] Microplastic degradation experiment: 40 mg of catalyst, 50 mg of microplastic, and 50 mL of deionized water are placed in a 100 mL beaker and continuously stirred at 25 °C for 9 h. During this 9 h period, 30 mg of PMS is added to the system every 3 h to obtain a mixed solution. At the T h th hour of "continuous stirring for 9 h", 10 mL of the mixed solution is taken, and the total organic carbon (TOC) concentration in the mixed solution at the T h th hour is measured using a Shimadzu total organic carbon analyzer (SHIMADZU TOC-LCPH). The microplastics in the mixed solution after 9 h of reaction are filtered and dried at 60 °C for 8 h to collect the degraded microplastics (for subsequent laser infrared testing). Among them, T<> h is one of 0 h, 3 h, 6 h, and 9 h, the catalyst is the cobalt-doped gallium oxide nanorod catalyst prepared in Example 3, the microplastic is one of PET, PPO, and PVC, and the pH of the mixed solution is 7.0.

[0092] T h The corresponding total organic carbon (TOC) concentrations of PET, PPO, and PVC at the time are as Figure 8 shown. From Figure 8It can be seen that as the degradation reaction continues, the TOC concentration in the mixed solution gradually increases, indicating that the microplastics in the mixed solution degrade under the Fenton-like reaction system. As a result, the carbon chains of the macromolecules of the originally water-insoluble microplastic polymers break under the attack of reactive species, generating small organic molecules soluble in water and causing the continuous increase of TOC in the mixed solution.

[0093] The Agilent 8700LDIR infrared imaging system was used to perform laser infrared tests on the microplastics before and after degradation, obtaining laser imaging pictures and generating particle size data. According to the particle size data, a trend graph with "diameter" on the abscissa and "proportion" on the ordinate was plotted, as Figure 9 shown. Figure 9 Inset a to Figure 9 Inset c of shows the laser imaging pictures of the microplastics (the bright spots in the laser imaging pictures are microplastic particles), specifically: Figure 9 In the left figure of a, it is the laser imaging picture of PET before degradation, and in the right figure is the laser imaging picture of PET after degradation; Figure 9 In the left figure of b, it is the laser imaging picture of PPO before degradation, and in the right figure is the laser imaging picture of PPO after degradation; Figure 9 In the left figure of c, it is the laser imaging picture of PVC before degradation, and in the right figure is the laser imaging picture of PVC after degradation. From Figure 9 Inset b to Figure 9 Inset c, it can be seen that the particle abundances of PPO and PVC after degradation both decrease significantly. At the same time, the average particle sizes of the microplastics after degradation all decrease to varying degrees. Among them, the average particle size of PVC decreases most significantly. The average particle size of PVC before degradation is 131.02 μm, and the average particle size after degradation is 77.66 μm.

[0094] The above makes an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification, or equivalent replacement that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention.

Claims

1. A cobalt-doped gallium oxide nanorod catalyst, characterized in that, It is Co-doped gallium oxide, and Co atoms are doped into the Ga2O3 lattice and replace some Ga atoms.

2. A preparation method of a cobalt-doped gallium oxide nanorod catalyst, characterized in that, It includes the following steps: Step 1: Mix a gallium source, a cobalt source, a surfactant, and water until homogeneous, adjust the pH to 7.0 - 8.0 using an alkaline solution, keep it at 135 - 140 °C for 7.5 - 8 h, cool to room temperature, centrifuge, wash, and dry to obtain a cobalt-doped gallium oxide nanorod catalyst precursor. Among them, in terms of the number of moles, the ratio of gallium in the gallium source to cobalt in the cobalt source is 15:(0.15 - 0.75); Step 2: In an air atmosphere, calcine the cobalt-doped gallium oxide nanorod catalyst precursor at 480 - 520 °C for 2 - 2.2 h to obtain a cobalt-doped gallium oxide nanorod catalyst.

3. The preparation method according to claim 2, characterized in that, In Step 1, the surfactant is sodium dodecylbenzenesulfonate.

4. The preparation method according to claim 2, characterized in that, In Step 1, the ratio of the number of moles of gallium in the gallium source, the number of moles of the surfactant, and the volume fraction of water is 15:3:(55 - 65). The unit of the number of moles is mmol, and the unit of the volume fraction is mL.

5. The preparation method according to claim 2, characterized in that, In Step 1, mix the gallium source, the cobalt source, the surfactant, and water, and stir at room temperature until homogeneous.

6. The preparation method according to claim 2, characterized in that, In Step 1, the alkaline solution is an NaOH aqueous solution, and the concentration of NaOH in the NaOH aqueous solution is 1.5 mol / L.

7. Application of cobalt-doped gallium oxide nanorod catalyst in removing pollutants, characterized in that, The cobalt-doped gallium oxide nanorod catalyst is one of the cobalt-doped gallium oxide nanorod catalysts described in Claim 1 and the cobalt-doped gallium oxide nanorod catalysts obtained by the preparation method described in any one of Claims 2 - 6.

8. The application according to claim 7, wherein The pollutants include: Antibiotic pollutants and / or microplastics.

9. The application according to claim 8, characterized in that, The antibiotic pollutants include one or more mixtures of tetracycline, doxycycline hydrochloride, ofloxacin, ciprofloxacin, and sulfamethoxazole.

10. The application according to claim 8, wherein The microplastics include one or more mixtures of PET, PPO, and PVC.

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