A cobalt oxyhydroxide catalyst and a preparation method thereof and a cooh / ptfe catalytic membrane

Abstract

The application discloses a cobalt oxyhydroxide catalyst, a preparation method thereof and a CoOOH / PTFE catalytic membrane, and belongs to the technical field of advanced oxidation water treatment.The CoOOH catalyst is prepared by using CoSO4.7H2O, (NH4)2S2O8 and K2SO4 as raw materials and adopting a hydrothermal method, and has a three-dimensional porous flower ball shape; due to the special morphology of the material, the removal rate of EE2 catalyzed by PMS can be as high as 95% or more, which is 2.39 times of the CoOOH prepared by a conventional precipitation method and 5.96 times of commercial Co3O4; the CoOOH material activated PMS catalyzed EE2 also has wide pH adaptability (pH: 3.0-10.0), cycle stability and low cobalt ion leaching concentration (0.0019 mg / L). In addition, the CoOOH material is loaded on a PTFE membrane by a vacuum filtration technology, a CoOOH / PTFE membrane-PMS system is built, and the system is applied to the continuous degradation of EE2 in actual water bodies, can be continuously treated for 24 hours, and can maintain a removal rate of 92.48%, and has potential practical application value.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation water treatment technology, specifically relating to a cobalt hydroxyl oxide catalyst and its preparation method, and a CoOOH / PTFE catalytic membrane. Background Technology

[0002] Water pollution caused by persistent organic pollutants poses a significant threat to the ecological environment and human health. Among them, 17α-ethynyl estradiol (EE2), a synthetic estrogen, is widely used in human oral contraceptives and drugs for treating prostate cancer and osteoporosis, as well as in livestock and aquaculture. Due to its long half-life, high toxicity, and resistance to biodegradation, EE2 has become widespread in aquatic environments, interfering with the endocrine systems of exposed organisms through environmental bioaccumulation, leading to reproductive disorders and sex reversal. Currently, EE2 has become a common problem in environmental pollution, and wastewater treatment plants and other traditional treatment processes are unable to achieve continuous, green, and complete removal of EE2. Therefore, there is an urgent need to explore a highly efficient, harmless, and widely applicable water treatment technology. In recent years, sulfate-based advanced oxidation processes (S-AOPs) have gradually become a popular method for treating organic pollutants in wastewater due to their advantages such as low cost and high reactivity. Among them, the transition metal-based catalyst activation technology for persulfate is simple to operate, fast to take effect, and low in operating cost. However, it also has drawbacks such as the difficulty in converting transition metal ions from high valence state to low valence state, low recovery rate of powdered catalysts, and secondary pollution caused by dispersion in water bodies, which limit its widespread application in the field of organic wastewater treatment.

[0003] Cobalt-based transition metals have high standard reduction potentials (Co). 3+ / Co 2+ (E0 = 1.92V), making it easier and more efficient to activate PMS. Among them, cobalt hydroxyl oxide (CoOOH), as an environmentally friendly mineral, has received widespread attention in the field of environmental remediation for the removal of organic matter by activating PMS, due to its advantages such as fast electron transport, relative stability, and low cost. The abundant hydroxyl groups and active sites on the surface of CoOOH are conducive to the adsorption and activation of PMS, and its good electron transport rate can promote electron transfer to quickly activate PMS. However, CoOOH catalysts still have problems such as low pollutant removal rate and poor pH adaptability. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a cobalt hydroxyoxide catalyst, its preparation method, and a CoOOH / PTFE catalytic membrane.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving CoSO4·7H2O, (NH4)2S2O8 and K2SO4 in water, then reacting the precipitate with hydrothermal reaction, washing it by centrifugation with ethanol and pure water, and then drying it to obtain the CoOOH catalyst.

[0007] In a preferred embodiment of the present invention, the molar ratio of CoSO4·7H2O, (NH4)2S2O8 and K2SO4 is 1:1:3.

[0008] In a preferred embodiment of the present invention, the hydrothermal reaction is carried out at a temperature of 100-160°C for 8-20 hours.

[0009] In a preferred embodiment of the present invention, the volume of the reaction vessel in the hydrothermal reaction is 30%-60%.

[0010] The present invention also claims protection for the preparation method of the cobalt hydroxyoxide catalyst to obtain a three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst.

[0011] As a preferred embodiment of the present invention, the surface of the three-dimensional porous flower-shaped cobalt hydroxyl oxide catalyst is rich in oxygen vacancies. The abundant oxygen vacancy defects are beneficial to accelerating electron transport and improving the catalyst activation efficiency of PMS.

[0012] A CoOOH / PTFE catalytic membrane includes a PTFE microporous filter membrane and a three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst supported on the PTFE microporous filter membrane.

[0013] In a preferred embodiment of the present invention, the three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst suspension on the CoOOH / PTFE catalytic membrane is loaded onto the PTFE membrane microporous filter membrane by vacuum filtration.

[0014] In a preferred embodiment of the present invention, the PTFE membrane microporous filter membrane has a pore size of 45 μm.

[0015] In a preferred embodiment of the present invention, the loading of the three-dimensional porous flower-shaped cobalt hydroxyl oxide catalyst on the CoOOH / PTFE catalytic membrane is 0.004-0.024 g / cm³. 2 .

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses CoSO4·7H2O, (NH4)2S2O8 and K2SO4 as raw materials to prepare a three-dimensional porous flower-shaped cobalt hydroxyl oxide catalyst by hydrothermal method. Due to the special morphology of the material, it can activate PMS to remove EE2 with a removal rate of up to 95% or more, which is 2.39 times that of CoOOH prepared by conventional precipitation method and 5.96 times that of commercial Co3O4. In addition, the CoOOH material activates PMS to catalyze EE2 with a wide pH adaptability (pH: 3.0-10.0), cycle stability, low cobalt ion leaching concentration (0.0019 mg / L) and good anti-interference ability, showing excellent PMS activation performance, good chemical stability and safety. Furthermore, this invention utilizes vacuum filtration technology to load CoOOH material onto a polytetrafluoroethylene (PTFE) membrane, which possesses high mechanical strength and resistance to acids, alkalis, and high temperatures, thus constructing a CoOOH / PTFE membrane-PMS system. This system was applied to the continuous degradation of EE2 in actual water bodies, capable of continuously treating 1.25L of Dianchi Lake water (Kunming, Yunnan) containing 3mg / L EE2 for 24 hours while maintaining a removal rate of 92.48%. This demonstrates its potential for practical application. This paper proposes that the CoOOH / PTFE membrane-PMS system holds promise for achieving green, efficient, and continuous treatment of organic pollutants in wastewater. Attached Figure Description

[0017] Figure 1 The preparation process of cobalt hydroxyoxide catalyst and CoOOH / PTFE catalytic membrane is described.

[0018] Figure 2 A catalytic membrane system for degrading organic pollutants using a CoOOH / PTFE catalytic membrane.

[0019] Figure 3The following graphs show the removal performance of EE2 by the catalysts prepared in Example 1 and Comparative Example 1: (a) EE2 removal activity of the PMS catalytic system, the CoOOH catalytic system prepared in Example 1, the p-CoOOH catalytic system prepared in Comparative Example 1, the PMS+CoOOH catalytic system, the PMS+p-CoOOH catalytic system, and the PMS+Co3O4 catalytic system; (b) EE2 removal activity of the PMS catalytic system, the CoOOH catalytic system prepared in Example 1, the p-CoOOH catalytic system prepared in Comparative Example 1, the PMS+CoOOH catalytic system, the PMS+p-CoOOH catalytic system, and the PMS+Co3O4 catalytic system; (c) EE2 removal activity of the PMS+CoOOH catalytic system. (d) The removal effect of EE2 in the initial organic pollutant solution with different pH values; (d) is the removal effect of EE2 in the organic pollutant solution with different water body configurations after PMS is activated by the PMS+CoOOH catalytic system. In the figure: PMS is the catalytic system with only PMS added; CoOOH is the catalytic system with only CoOOH prepared in Example 1 added; p-CoOOH is the catalytic system with only p-CoOOH prepared in Comparative Example 1 added; PMS+CoOOH is the catalytic system with PMS and CoOOH prepared in Example 1 added; PMS+p-CoOOH is the catalytic system with PMS and p-CoOOH prepared in Comparative Example 1 added; PMS+Co3O4 is the catalytic system with PMS and Co3O4 added.

[0020] Figure 4 The figures show the EE2 removal performance of CoOOH / PTFE catalytic membranes and PTFE membranes with different CoOOH / loading ratios; (a) EE2 removal performance of CoOOH / PTFE catalytic membranes and PTFE membranes with different CoOOH / loading ratios; (b) Comparison of membrane flux of CoOOH / PTFE catalytic membranes and PTFE membranes with different CoOOH / loading ratios; (c) Effect of continuous treatment of actual water bodies by the CoOOH / PTFE catalytic membrane prepared in Example 2. In the figures: PTFE membrane refers to the catalytic system with only PTFE added; PTFE membrane + PMS refers to the catalytic system with only PTFE added. PTFE membranes and PMS were added to the system; CoOOH / PTFE catalytic membrane - 0.05 + PMS refers to the CoOOH / PTFE catalytic membrane and PMS loaded with 0.05 g of CoOOH prepared in Example 1 added to the catalytic system; CoOOH / PTFE catalytic membrane - 0.1 + PMS refers to the CoOOH / PTFE catalytic membrane and PMS prepared in Example 2 added to the catalytic system; CoOOH / PTFE catalytic membrane - 0.3 + PMS refers to the CoOOH / PTFE catalytic membrane and PMS loaded with 0.3 g of CoOOH prepared in Example 1 added to the catalytic system.

[0021] Figure 5 The following graphs show the stability of the CoOOH-activated PMS prepared in Example 1 for EE2 removal: (a) shows the effect of EE2 removal after 5 cycles using the CoOOH-activated PMS prepared in Example 1; (b) shows the comparison of Co leaching concentration in EE2 solutions with different pH values ​​using the CoOOH-activated PMS prepared in Example 1 for EE2 removal.

[0022] Figure 6 The image shows a comparison of the XRD patterns of CoOOH prepared in Example 1 before and after PMS activation to remove EE2.

[0023] Figure 7 The images show the XRD and FTIR spectra of CoOOH prepared in Example 1 and p-CoOOH prepared in Comparative Example 1. (a) is the XRD spectra, and (b) is the FTIR spectra. In the figures, CoOOH is the CoOOH prepared in Example 1, and p-CoOOH is the p-CoOOH prepared in Comparative Example 1.

[0024] Figure 8 The images show the morphology and N2 adsorption-desorption isotherms of the materials prepared in Example 1 and Comparative Example 1; (a) is a SEM image of CoOOH prepared in Example 1; (b) is a SEM image of p-CoOOH prepared in Comparative Example 1; (c) is a N2 adsorption-desorption isotherm of the materials prepared in Example 1 and Comparative Example 1; (d) is a low-magnification TEM image of CoOOH prepared in Example 1; (e) is a high-magnification TEM image of CoOOH prepared in Example 1; (f) is a high-magnification TEM image of CoOOH prepared in Example 1; (g) is an EDS energy spectrum of the O element on the surface of CoOOH prepared in Example 1; and (h) is an EDS energy spectrum of the Co element on the surface of CoOOH prepared in Example 1. Detailed Implementation

[0025] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving 0.02 mol of CoSO4·7H2O, 0.02 mol of (NH4)2S2O8 and 0.06 mol of K2SO4 in 70 mL of deionized water, stirring for 2 h, transferring to a 200 mL polytetrafluoroethylene reactor, placing it in a constant temperature drying oven and reacting at 140 °C for 14 h, removing the precipitate obtained after the reaction, washing it three times with ethanol and pure water by centrifugation, and drying it overnight at 60 °C to obtain the CoOOH catalyst, denoted as CoOOH.

[0028] Example 2

[0029] like Figure 1 As shown, a method for preparing a CoOOH / PTFE catalytic membrane includes the following steps: A PTFE microporous filter membrane with a diameter of 47 mm (pore size of 45 μm) is soaked in ethanol and deionized water for 1 hour each to remove surface impurities, and then dried at 60°C overnight. 0.1 g of the CoOOH catalyst material prepared in Example 1 is weighed and dissolved in 100 mL of deionized water, ultrasonically dispersed until uniform, and the CoOOH material is vacuum filtered onto a PTFE filter membrane and dried at 60°C overnight. The resulting cobalt hydroxyl oxide catalyst has a loading of 0.018 g / cm³. 2 CoOOH / PTFE membrane.

[0030] Example 3

[0031] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving 0.02 mol of CoSO4·7H2O, 0.02 mol of (NH4)2S2O8 and 0.06 mol of K2SO4 in 70 mL of deionized water, stirring for 2 h, transferring to a 200 mL polytetrafluoroethylene reactor, placing it in a constant temperature drying oven and reacting at 160 °C for 20 h, removing the precipitate obtained after the reaction, washing it three times with ethanol and pure water by centrifugation, and drying it overnight at 60 °C to obtain the CoOOH catalyst, denoted as CoOOH.

[0032] Example 4

[0033] A method for preparing a CoOOH / PTFE catalytic membrane includes the following steps: A PTFE microporous filter membrane with a diameter of 47 mm (pore size of 45 μm) is soaked in ethanol and deionized water for 1 hour each to remove surface impurities, and then dried at 60°C overnight. 0.025 g of the CoOOH catalyst material prepared in Example 3 is weighed and dissolved in 100 mL of deionized water, ultrasonically dispersed until uniform, and the CoOOH material is vacuum filtered onto a PTFE filter membrane and dried at 60°C overnight. The resulting cobalt hydroxyl oxide catalyst has a loading of 0.004 g / cm³. 2 CoOOH / PTFE membrane.

[0034] Example 5

[0035] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving 0.02 mol of CoSO4·7H2O, 0.02 mol of (NH4)2S2O8 and 0.06 mol of K2SO4 in 70 mL of deionized water, stirring for 2 h, transferring to a 200 mL polytetrafluoroethylene reactor, placing it in a constant temperature drying oven and maintaining the reaction at 100 °C for 8 h, removing the precipitate obtained after the reaction, washing it three times with ethanol and pure water by centrifugation, and drying it overnight at 60 °C to obtain the CoOOH catalyst, denoted as CoOOH.

[0036] Example 6

[0037] A method for preparing a CoOOH / PTFE catalytic membrane includes the following steps: A PTFE microporous filter membrane with a diameter of 47 mm (pore size of 45 μm) is soaked in ethanol and deionized water for 1 hour each to remove surface impurities, and then dried overnight at 60°C. 0.25 g of the CoOOH catalyst material prepared in Example 4 is weighed and dissolved in 100 mL of deionized water, ultrasonically dispersed until uniform, and the CoOOH material is vacuum filtered onto a PTFE filter membrane and dried overnight at 60°C. The resulting cobalt hydroxyl oxide catalyst has a loading of 0.024 g / cm³. 2 CoOOH / PTFE membrane.

[0038] Comparative Example 1

[0039] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: 50 mL of 10 mM CoCl₂·H₂O is placed in a 100 mL beaker, and 12.5 mL of 1 M NaOH solution is added dropwise. The mixture is sonicated for 10 min until uniformly dispersed. Then, 2.5 mL of 0.9 M NaClO solution is added dropwise, and the mixture is sonicated for 30 min. After centrifugation and washing, the material is collected and dried overnight at 60 °C. The obtained material is designated as p-CoOOH.

[0040] Figure 7 (a) The XRD patterns of CoOOH prepared in Example 1 and p-CoOOH prepared in Comparative Example 1 are shown. The diffraction peaks of both are in good agreement with the hexagonal phase CoOOH (PDF#73-1213). Among them, the (003), (101), (012), (015), (110) and (113) crystal planes of this structure can be perfectly matched at 2θ = 20.24°, 37.01°, 38.93°, 50.67°, 65.41° and 69.25°, and are also consistent with the structure. Figure 7As shown in the FTIR image (b), both Example 1 and Comparative Example 1 successfully synthesized CoOOH materials. Comparing the materials synthesized by the two methods in Example 1 and Comparative Example 1, the XRD patterns show that the CoOOH prepared in Example 1 has a stronger diffraction peak on the (003) crystal plane, indicating that the cobalt hydroxyl oxide catalyst prepared in Example 1 of this invention has a preferred orientation structure along the (003) plane. Figure 7 As shown, the three-dimensional porous flower-shaped cobalt hydroxyl oxide catalyst prepared in Example 1 has a surface rich in oxygen vacancies. These abundant oxygen vacancy defects are beneficial for accelerating electron transport and improving the catalyst's PMS activation efficiency. According to... Figure 8 As can be seen from (a)-(b) and (d)-(h), the CoOOH material prepared in Example 1 of this invention has a three-dimensional porous flower-shaped morphology with a hollow structure assembled from thin nanosheets, with many pores inside, exposing many active sites, and the Co and O elements are evenly distributed; the p-CoOOH material prepared in Comparative Example 1 has a morphology of nanoparticles agglomerated into a blocky shape. Figure 8 (c) It can be seen that both the CoOOH prepared in Example 1 and the p-CoOOH prepared in Comparative Example 1 have mesoporous structures, but CoOOH has a larger specific surface area of ​​67.28 m². 2 / g, with an average pore size of 35.65nm. In summary, compared with p-CoOOH, the unique morphology of CoOOH is more conducive to the diffusion, adsorption, and desorption of pollutants on the catalyst surface, thereby improving the catalytic efficiency.

[0041] Comparative Example 2

[0042] The only difference between the preparation method of the CoOOH / PTFE catalytic membrane described in this comparative example and that in Example 2 is that the CoOOH catalyst material prepared in Example 2 is replaced with the p-CoOOH prepared in Comparative Example 1.

[0043] Comparative Example 3

[0044] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving 0.02 mol of CoSO4·7H2O, 0.02 mol of (NH4)2S2O8 and 0.06 mol of NaOH in 70 mL of deionized water, stirring for 2 h, transferring to a 200 mL polytetrafluoroethylene reactor, placing it in a constant temperature drying oven and reacting at 140 °C for 14 h, removing the precipitate obtained after the reaction, washing it three times with ethanol and pure water by centrifugation, and drying it overnight at 60 °C to obtain the CoOOH catalyst.

[0045] Comparative Example 4

[0046] The only difference between the preparation method of the CoOOH / PTFE catalytic membrane described in this comparative example and that in Example 2 is that the CoOOH catalyst material prepared in Example 2 is replaced with the CoOOH catalyst prepared in Comparative Example 3.

[0047] Comparative Example 5

[0048] A method for preparing a cobalt hydroxyl oxide catalyst includes the following steps: dissolving 0.02 mol of CoCl2·6H2O, 0.02 mol of (NH4)2S2O8 and 0.06 mol of K2SO4 in 70 mL of deionized water, stirring for 2 h, transferring to a 200 mL polytetrafluoroethylene reactor, placing it in a constant temperature drying oven and reacting at 140 °C for 14 h, removing the precipitate obtained after the reaction, washing it three times with ethanol and pure water by centrifugation, and drying it overnight at 60 °C to obtain the CoOOH catalyst.

[0049] Comparative Example 6

[0050] The only difference between the preparation method of the CoOOH / PTFE catalytic membrane described in this comparative example and that in Example 2 is that the CoOOH catalyst material prepared in Example 2 is replaced with the CoOOH catalyst prepared in Comparative Example 5.

[0051] Example 1

[0052] Powdered catalysts prepared in Examples 1, 3, and 5 and Comparative Examples 1, 3, and 5 for the degradation of organic pollutants: In this study, 3 mg / L EE2 was used as the target pollutant. The performance of the catalysts was tested at room temperature (approximately 25 ± 2 °C). The specific method is as follows: 50 mL of a 3 mg / L EE2 solution and 0.2 g / L of catalyst material were added to a 150 mL Erlenmeyer flask. The flask was then transferred to a constant-temperature shaker and shaken for 20 min until adsorption-desorption equilibrium was reached. Then, 0.03 g / L of PMS was added to the Erlenmeyer flask, and the mixture was continuously shaken until homogeneous. After each reaction period, 3 mL of solution was transferred using a syringe and filtered through a glass fiber filter. The EE2 concentration in the solution after the reaction was determined by ultra-high performance liquid chromatography (UHPLC). Performance data are shown below. Figure 3 and Figure 4 .

[0053] The catalytic membranes prepared in Examples 2, 4, and 6 and Comparative Examples 2, 4, and 6 degrade organic pollutants: Figure 2As shown, the catalytic membrane system consists of a peristaltic pump, feed solution, filtrate, catalytic membrane, and a fixed-mode reactor. 200 mL of a 3 mg / L EE2 solution was placed in a 500 mL beaker, and 0.03 g / L PMS was added and stirred until homogeneous to obtain the feed solution. The prepared CoOOH / PTFE catalytic membrane was placed in the reactor. The feed solution was pumped through the catalytic membrane to obtain the filtrate after the reaction, and the filtrate was not returned to the feed solution. The filtrate was collected at certain time intervals, and the EE2 concentration was measured using ultra-high performance liquid chromatography (UHPLC). Performance data are shown in [link to performance data]. Figure 3 and Figure 4 .

[0054] The removal efficiency of the catalyst for EE2 is calculated using the following formula:

[0055] R = C / C0 × 100%;

[0056] In the formula, R is the EE2 content (%) in the solution after a certain time, and C0 and C are the initial concentration and concentration of EE2 after a certain reaction time, respectively.

[0057] The data from the experiment on the degradation of EE2 by catalyst-activated PMS were fitted using the pseudo-first-order kinetic reaction rate equation, as shown in the following equation:

[0058] ln(C / C0)=kt

[0059] In the formula, k is the catalytic reaction rate constant, and t is the reaction time.

[0060] The formula for calculating the water flux of a catalytic membrane is:

[0061] J = Vw / (Sⅹt);

[0062] J represents the water flux, Vw is the volume of solution passing through the membrane (L), and S is the effective area of ​​the catalytic membrane (m²). 2 ), where t is the filtering time (h).

[0063] like Figure 3 As shown in (a) and (b), when only PMS, CoOOH prepared in Example 1, or p-CoOOH prepared in Comparative Example 1 were added to the catalytic system, the removal rate of EE2 was less than 10%, indicating that the unactivated PMS, CoOOH prepared in Example 1, or p-CoOOH prepared in Comparative Example 1 had limited ability to oxidize and remove EE2. After activating PMS with CoOOH prepared in Example 1 or p-CoOOH prepared in Comparative Example 1, the CoOOH / PMS system achieved a 95.62% EE2 removal rate within 9 minutes, with a constant reaction rate of 0.36557 min. -1The efficiency of the p-CoOOH / PMS system prepared in Comparative Example 1 (where p-CoOOH is a sheet-like material) was 2.39 times that of the commercial Co3O4-PMS system, and 5.96 times that of the commercial Co3O4-PMS system. This indicates that the three-dimensional porous flower-shaped CoOOH material prepared by the one-step hydrothermal method has great potential in activating PMS to degrade pollutants. The CoOOH / PMS systems prepared in Examples 3 and 5 achieved a removal rate of over 94% for EE2 within 9 minutes.

[0064] like Figure 4 As shown in (a), the PTFE membrane showed almost no retention of EE2 (the removal rate of EE2 was only 10.45%). In the catalytic system with only PMS added, the removal rate of EE2 within 40 min was 9.15%, indicating that the oxidation capacity of PMS is limited without activation. Loading CoOOH material onto the PTFE membrane significantly improved the catalytic performance. With material loadings of 0.05 g, 0.1 g (Example 2), and 0.2 g, the removal rates of EE2 by the catalytic membrane system were 71.03%, 95.23%, and 57.45%, respectively. With only 0.05 g of CoOOH material, only a small portion of the active sites were provided for activating PMS, resulting in unsatisfactory removal. When the CoOOH material loaded on the membrane was 0.3 g, a large amount of catalyst agglomerated and clumped during vacuum filtration, failing to fully expose the active sites. The CoOOH / PMS systems prepared in Examples 4 and 6 achieved a removal rate of over 94% of EE2 within 40 min.

[0065] The materials prepared in Comparative Examples 3 and 5 were sheet-like, and their activation effect on PMS catalysis of EE2 was not ideal.

[0066] The CoOOH / PTFE catalytic membranes prepared in Comparative Examples 2, 4 and 6 exhibited poor degradation performance due to the limited ability of the CoOOH material to activate PMS degradation.

[0067] Example 2

[0068] Example 1: The powdered catalysts prepared in Comparative Examples 1, 3, and 5 degraded organic pollutants in initial organic pollutant solutions at different pH values: The pH of the initial solution (3 mg / L EE2 solution) was adjusted to 3, 4, 6.5, 8, and 10 by 0.1 M NaOH or 0.1 M HCl. Then, the powdered catalysts activated PMS at room temperature (around 25 ± 2 °C) to remove (adsorb and degrade) EE2 in the initial organic pollutant solutions at different pH values.

[0069] like Figure 3(c) It can be seen that the adsorption efficiency of the system for EE2 within 20 min differed significantly when the solution pH was 3.0, 4.0, 6.5, 8.0, and 10.0, respectively, being 48.74%, 20.12%, 9.69%, 11.24%, and 9.38%. This indicates that pH has a significant impact on the adsorption of the target pollutant by the catalyst. This is mainly because the surface isoelectric point of the CoOOH material prepared in Example 1 is 6.8. When the pH is less than 6.8, the catalyst material surface carries a positive potential, enhancing the electrostatic adsorption of EE2. When the pH is greater than 6.8, the material surface carries a negative potential, and the attraction between it and the acidic PMS gradually decreases with increasing solution pH, inhibiting degradation. However, in the subsequent degradation catalytic stage, the system exhibited extremely high removal rates (greater than 95.95%) for EE2 at different pH values. This means that there is a pH-insensitive non-radical pathway in the degradation process, which fully demonstrates that the CoOOH / PMS reaction system can achieve rapid degradation of EE2 through surface adsorption-catalysis synergy within a wide pH range (pH = 3.0-10.0).

[0070] The CoOOH material prepared in this invention has a three-dimensional porous flower-shaped structure, so its mechanism of activating PMS to degrade EE2 does not depend on the solution pH value. However, since the materials prepared in Comparative Examples 1, 3 and 5 have a plate-like morphology, which affects the pathway of their activation of PMS to degrade EE2, their dependence on solution pH is relatively strong.

[0071] Example 3

[0072] To explore the effects of various inorganic ions and complex organic components in organic pollutant solutions on the activation of PMS by CoOOH catalyst for EE2 catalysis, this study used pure water, tap water, or Dianchi Lake water to prepare EE2 solutions. The powdered catalyst was then used to activate PMS at room temperature (approximately 25±2℃) to remove (adsorb and degrade) EE2 from organic pollutant solutions prepared in different water bodies.

[0073] like Figure 3 As shown in Figure d, the EE2 removal rates of the CoOOH / PMS system prepared in Example 1 in the three water bodies were 96.52%, 95.38%, and 95.69%, respectively. Tap water contains a large amount of anions (Cl... - H2PO4 - CO3 2- NO 3- and SO4 2- Dianchi Lake contains a large number of anions (Cl-, H2PO4). - CO3 2- NO 3- and SO4 2-Experimental results show that the CoOOH / PMS system can degrade pollutants in complex water bodies, including metal ions and organic matter (HA), and has excellent prospects for practical application.

[0074] Example of effect 4

[0075] The catalytic stability of Examples 1-2 and Comparative Examples 1-6 was explored.

[0076] (1) The catalyst material after the catalytic reaction in Example 1 was collected by centrifugation, and the residual substances on the catalyst surface were washed away with ethanol. It was then used to activate PMS to degrade EE2 for 5 cycles, each with an adsorption-catalysis time of 30 min.

[0077] from Figure 5 It can be seen that after five cycles, the EE2 removal rate of the CoOOH material prepared in Example 1 decreased from 96.34% to 92.54%. Figure 6 The XRD patterns of the CoOOH material prepared in Example 1 before and after the reaction show that its phase remains unchanged, indicating that the material can be reused. Furthermore, the metal ion leaching amount of the CoOOH-PMS system prepared in Example 1 after degrading EE2 in solutions of different pH values ​​was tested using ICP (CoOOH concentration in the CoOOH-PMS system was 0.20 g / L; PMS concentration was 0.03 g / L). The experimental results are as follows. Figure 5 As shown in (b), the ion leaching concentration of the CoOOH catalyst prepared in Example 1 was lower than the Chinese standard (GB 25467-2010: 0.01 mg / L) in the pH range of 4-10. Moreover, under strongly alkaline conditions, almost no cobalt ions were dissolved in the solution, indicating that the material has not only high catalytic performance but also green and safe potential for practical application.

[0078] Compared with Comparative Examples 1-6, the materials prepared in Examples 1-2 of the present invention have better stability and lower Co leaching rate.

[0079] (2) The value of the catalytic membrane system in practical applications: A 3 mg / L EE2 solution was prepared using an actual water sample (January 17, 2024, taken from Dianchi Lake, Kunming) to investigate the catalytic effect of the catalytic membrane on the actual water body using a continuous flow method. For example... Figure 4 As shown in (c), the catalytic membrane system prepared in Example 1 can continuously treat Dianchi Lake water samples containing EE2 for 24 hours, with a wastewater treatment volume of 1.25L, and the EE2 removal rate can still be maintained at 92.48%, indicating that the CoOOH / PTFE catalytic membrane system has broad application prospects and excellent practical application potential.

[0080] (3) The flux of the catalytic membrane plays an important role in the stable operation of the catalytic membrane system. The catalytic membranes prepared in Examples 2, 2, 4, and 6 degraded organic pollutants for 40 minutes, and the flux of the catalytic membrane was measured and calculated. Figure 4 (b) It can be seen that after 40 min of reaction, the flux of the PTFE membrane is 45.62 L / (m²). -2 h -1 The flux of the catalytic membranes loaded with 0.05, 0.1, and 0.3 g of material remained at 48.38, 47.68, and 46.81 L / (m³), respectively. -2 h -1 The wetting properties of the catalytic membrane were studied by contact angle testing. The water contact angle of the PTFE membrane was 118°, and the water contact angle of the CoOOH / PTFE catalytic membrane prepared in Example 1 was 60°, demonstrating good hydrophilicity. This is because the loading of CoOOH material increases the surface hydrophilic hydroxyl groups of the catalytic membrane, thereby improving the hydrophilicity of the catalytic membrane. This not only increases the membrane flux but also gives the catalytic membrane a certain degree of antifouling ability, which is beneficial for wastewater treatment. However, if too much catalyst is loaded, it will also cause catalyst agglomeration and block the pores on the membrane, resulting in a decrease in membrane flux. Therefore, the most suitable catalyst loading was selected as 0.1 g.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a cobalt hydroxyoxide catalyst, characterized in that, The process includes the following steps: CoSO4·7H2O, (NH4)2S2O8 and K2SO4 are dissolved in water, and the precipitate obtained by hydrothermal reaction is washed by centrifugation with ethanol and pure water, and then dried to obtain the CoOOH catalyst.

2. The method for preparing the cobalt hydroxyl oxide catalyst as described in claim 1, characterized in that, The molar ratio of CoSO4·7H2O, (NH4)2S2O8 and K2SO4 is 1:1:

3.

3. The method for preparing the cobalt hydroxyl oxide catalyst as described in claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100-160℃ for 8-20 hours.

4. The method for preparing the cobalt hydroxyl oxide catalyst as described in claim 1, characterized in that, The volume of the reactor in the hydrothermal reaction is 30%-60%.

5. The method for preparing the cobalt hydroxyoxide catalyst according to any one of claims 1-4 yields a three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst.

6. The cobalt hydroxyl oxide catalyst according to claim 5, characterized in that, The surface of the three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst is rich in oxygen vacancies.

7. A CoOOH / PTFE catalytic membrane, characterized in that, The three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst of claim 6 includes a PTFE microporous membrane and a PTFE microporous membrane supported on the PTFE microporous membrane.

8. The CoOOH / PTFE catalytic membrane according to claim 7, characterized in that, The three-dimensional porous flower-shaped cobalt hydroxyoxide catalyst suspension on the CoOOH / PTFE catalytic membrane was loaded onto the PTFE membrane microporous filter membrane by vacuum filtration.

9. The CoOOH / PTFE catalytic membrane according to claim 7, characterized in that, The PTFE microporous filter membrane has a pore size of 45 μm.

10. The CoOOH / PTFE catalytic membrane according to claim 7, characterized in that, The loading of the three-dimensional porous flower-shaped cobalt hydroxyl oxide catalyst on the CoOOH / PTFE catalytic membrane is 0.004-0.024 g / cm³. 2 .

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