An orbital-regulated α-MnO2@CNT hybrid and its effect on the selective generation of IO3 from periodate. • Applications in

Abstract

This invention discloses an orbital-controlled α-MnO2@CNT hybrid and its selective generation of IO3 upon activation of periodate (PI). • Applications in [the field]. This hybrid material uses α-MnO2 nanoribbons as the active component and CNTs as the electron reservoir, and is prepared via a one-step co-precipitation method. The CNTs and α-MnO2 form an interfacial hybrid structure, which can modulate the electronic state density of the Mn 3d orbitals, shifting the Mn d-band center upwards and enhancing PI adsorption and interfacial electron transfer efficiency. When this hybrid material is added as a catalyst to water containing PI and mixed pollutants, it can selectively generate IO3-. • Main, 1 O2 is a secondary active species, enabling the simultaneous and efficient degradation of mixed pollutants, including sulfonamide antibiotics and Rhodamine B. This invention features a simple and low-cost preparation process, a catalyst with good stability and strong anti-interference ability, wide applicability, and no formation of toxic iodides, providing a new technical solution and theoretical support for the remediation of complex water bodies.

Description

Technical Field

[0001] This invention relates to the fields of environmental chemistry and advanced oxidation technologies, specifically to an orbital-regulated α-MnO2@CNT hybrid and its role in activating periodate (PI, IO4). - Selective generation of iodine radicals (IO3) • Its application in water treatment technology is particularly suitable for the simultaneous and efficient degradation of mixed pollutants such as antibiotics and dyes in complex water bodies. Background Technology

[0002] The combined production or mixed emissions from the pharmaceutical, dyeing, and chemical industries result in the coexistence of sulfonamide antibiotics and dyes such as Rhodamine B (RhB) in water bodies. This complex pollution of recalcitrant organic pollutants exacerbates toxicity, and conventional treatment methods struggle to achieve simultaneous and efficient removal. Existing treatment technologies often employ a combination of advanced oxidation and adsorption processes, which suffer from long treatment cycles and high operating costs. Therefore, developing a single process capable of simultaneously and efficiently removing multiple pollutants has significant application value.

[0003] Advanced oxidation techniques based on periodate (PI) do not produce significant color and pH changes during the reaction process and can generate a variety of reactive species (such as iodine radical IO3). • Singlet oxygen 1 O2, hydroxyl radicals • PI (Polyimide) has become a highly promising water remediation technology. Both transition metal-based and carbon-based materials can be used as PI activators, among which MnO2 has been proven to be a potential PI activator due to its strong coordination ability with PI.

[0004] However, the ability of pure-phase MnO2 to activate PI is still insufficient, especially in the formation of highly oxidizing IO3. • The low efficiency in this aspect results in a slow pollutant degradation rate, failing to meet the requirements for the simultaneous and efficient removal of recalcitrant sulfonamide antibiotics and dye mixtures in complex water bodies. The core reason lies in the Mn content in MnO2. 4+ The low density of 3d orbitals and weak electronic activity near the Fermi level limit the adsorption capacity of PI. Furthermore, the high energy barrier for electron transfer from the catalyst to PI further restricts the adsorption of IO3. • The generation efficiency.

[0005] Currently reported MnO2 / PI systems mainly generate adsorbed reactive oxygen species through strong coordination between MnO2 and PI, thereby generating... 1 O2, IO3 • As a secondary active species, it is difficult to fully utilize its high oxidizing power. Therefore, how to reduce IO3 by regulating the electronic structure of MnO2 is a key issue. •The generated energy barrier enables the PI activation path to IO3. • Leading the shift has become key to solving existing technological bottlenecks. Summary of the Invention

[0006] The purpose of this invention is to overcome the low activation efficiency of pure-phase MnO2 for PI and the low efficiency of IO3 in the prior art. • To address the shortcomings of insufficient generation and difficulty in simultaneously degrading mixed pollutants, this paper provides an orbital-controlled α-MnO2@CNT hybrid and its preparation method, as well as its role in activating the selective generation of IO3 from periodate. • Applications in [the field]. This hybrid enhances PI adsorption and interfacial electron transfer efficiency by modulating the Mn 3d orbitals through carbon nanotubes (CNTs), preferentially reducing IO3 [organisms]. • The generated energy barrier enables the efficient and simultaneous removal of mixed pollutants, providing new technical solutions and theoretical support for the remediation of complex water bodies.

[0007] The objective of this invention can be achieved by adopting the following technical solutions:

[0008] An orbital-controlled α-MnO2@CNT hybrid is characterized in that the hybrid is prepared by a one-step co-precipitation method, with α-MnO2 nanoribbons as the active component and carbon nanotubes (CNTs) as the electron reservoir. CNTs and α-MnO2 form an interfacial hybrid structure, which regulates the electronic density of states of the Mn 3d orbital, causing the Mn d band center to shift from -0.296 eV to 0.038 eV, thereby enhancing the interaction between the hybrid and periodate (PI) and the interfacial electron transfer capability.

[0009] The preparation method of the orbital-controlled α-MnO2@CNT hybrid includes the following steps:

[0010] Step 1, Reagent preparation: Select manganese acetate tetrahydrate ((CH3COO)2Mn·4H2O), potassium permanganate (KMnO4), carbon nanotubes (CNTs) and other analytical grade reagents. All reagents can be used directly without further purification.

[0011] Step 2, Mixing and Dispersion: Add manganese acetate tetrahydrate, potassium permanganate, and carbon nanotubes to deionized water and stir until homogeneous to form a dispersion; wherein the molar ratio of manganese acetate tetrahydrate to potassium permanganate is 1:(1.2~1.5), and the amount of carbon nanotubes added is 5%~15% of the theoretical amount of α-MnO2 generated;

[0012] Step 3, coprecipitation reaction: Place the above dispersion in a constant temperature water bath and stir at 60~80 ℃ for 2~4 hours. Stir continuously during the reaction to ensure uniform reaction.

[0013] Step 4, Separation and Drying: After the reaction is completed, the reaction solution is centrifuged and separated. The resulting precipitate is washed with deionized water and ethanol 3 to 5 times to remove impurities. Then, it is vacuum dried at 60 to 80 °C for 6 to 12 hours to obtain orbital-controlled α-MnO2@CNT hybrid.

[0014] The orbital-controlled α-MnO2@CNT hybrid activates the selective generation of IO3 from periodate. • The application of this method is characterized by using the hybrid as a catalyst in water containing periodate and mixed pollutants. Under normal temperature and natural pH conditions, the hybrid activates periodate, selectively generating IO3. • Main, 1 O2 is a secondary active species, enabling the simultaneous degradation of mixed pollutants;

[0015] The mixed contaminant is a mixture of sulfonamide antibiotics and rhodamine B (RhB), wherein the sulfonamide antibiotics include one or more of sulfadiazine (SDZ), sulfapyridine (SPD), and sulfamethoxazole (SMZ).

[0016] The catalyst is added at a rate of 0.3~0.7 g·L. -1 The concentration of periodate was 0.1–0.3 mM, and the concentration of each component in the mixed pollutants was 5–20 mg·L⁻¹. -1 ;

[0017] The reaction conditions were: temperature 20–30 °C, pH 3.3–9.3, and stirring rate 200–300 r·min. -1 The reaction time is 5 to 30 minutes.

[0018] Furthermore, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10~20 nm and a length of 1~5 μm, and are pre-treated with nitric acid to enhance their dispersibility and interfacial interaction with α-MnO2.

[0019] Furthermore, in step 3, the temperature of the constant temperature water bath is preferably 70 ℃, and the reaction time is preferably 3 hours; in step 4, the temperature of vacuum drying is preferably 70 ℃, and the drying time is preferably 8 hours.

[0020] Furthermore, the preferred dosage of the catalyst is 0.5 g·L⁻¹. -1 The preferred concentration of periodate is 0.2 mM, and the concentration of each component in the mixed pollutant is 10 mg·L⁻¹. -1 The preferred reaction temperature is 25 °C, and the preferred pH is 5.3.

[0021] The principle of this invention is as follows: an α-MnO2@CNT hybrid structure is constructed by a one-step coprecipitation method. The unique delocalized π system and strong interfacial interaction of CNT are used to regulate the Mn 3d orbitals. On the one hand, the electronic state density of the Mn 3d orbitals near the Fermi level is increased, and on the other hand, the center of the Mn d band is moved towards the Fermi level, thereby enhancing the adsorption capacity of the hybrid for PI (the adsorption energy decreases from -2.16 eV to -3.18 eV) and promoting interfacial electron transfer (the amount of electron transfer increases from 1.097 |e| to 1.212 |e|).

[0022] During PI activation, there are two reaction pathways: 1) Intramolecular electron transfer pathway (coordination-driven), where PI strongly coordinates with the Mn site, resulting in intramolecular electron transfer to generate Mn–O. • Subsequently, Mn–O • Generate by combining with each other 1 O2; 2) Interfacial electron transfer pathway: PI adsorbed at Mn sites generates Mn–O through interfacial electron transfer. - and IO3 • Due to the modulation of the Mn 3d orbitals, the energy barrier of the interfacial electron transfer pathway (1.92 eV) is significantly lower than that of the intramolecular electron transfer pathway (2.45 eV), enabling the PI activation pathway to move towards IO3. • The dominant shift, IO3 • With its high oxidizing properties and good water compatibility, it enables the rapid and simultaneous degradation of mixed pollutants.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Significant effect of electronic structure modulation: Through the hybridization of α-MnO2 and CNT, the precise modulation of Mn 3d orbitals is achieved, which significantly increases the electronic density of states near the Fermi level and reduces IO3. • The energy barrier created causes the active species to shift from being dominated by pure-phase MnO2. 1 O2 transforms into hybrid-dominant IO3. • This significantly improves the efficiency of pollutant degradation;

[0025] (2) Excellent degradation performance of mixed pollutants: The α-MnO2@CNT / PI system can achieve 10 mg·L⁻¹ degradation within 15 minutes. -1 Complete degradation of sulfadiazine (rate constant 0.44 min) -1 Achieve 10 mg·L within 5 minutes -1 Complete degradation of Rhodamine B (rate constant 2.37 min) -1 Its performance is superior to most reported PI-activated catalyst systems;

[0026] (3) Wide applicability and strong anti-interference ability: The system can maintain high efficiency in degradation within the pH range of 3.3 to 9.3, and is effective against common coexisting ions in water (such as NO3-). - SO4 2- HPO4 2- It exhibits good tolerance to humic acid (HA) and other substances, and can still maintain a degradation efficiency of over 85% in actual water bodies such as Pearl River water, urban sewage, and tap water.

[0027] (4) The preparation method is simple and the cost is low: it is prepared by one-step co-precipitation method, which is simple and convenient to operate, does not require complicated equipment, has low reagent cost, and is easy to scale up production;

[0028] (5) Good stability and safety: The catalyst can be recycled at least 4 times without significant performance degradation, and the amount of Mn ions dissolved during the reaction is extremely low (only 0.051 mg·L⁻¹). -1 ), without toxic iodides (such as HOI, I2 / I3) - ) generates only non-toxic IO3. - Low environmental risk;

[0029] (6) Broad application prospects: It can be widely applied to the simultaneous degradation of various sulfonamide antibiotics and dyes mixed pollutants in complex water bodies, providing new ideas and technical support for the application of advanced oxidation technology in the field of water treatment. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the preparation process and periodate activation mechanism of orbital-controlled α-MnO2@CNT hybrids;

[0031] Figure 2 These are structural characterization diagrams of α-MnO2@CNT hybrids and related materials; where (a) is the SEM image of CNTs, (b) is the SEM image of α-MnO2, (c) is the TGA curve of α-MnO2@CNT hybrids, (d) is the SEM image of α-MnO2@CNT hybrids, (e) is the TEM image of α-MnO2@CNT hybrids, (f) is the HRTEM image of α-MnO2@CNT hybrids, (g) is the SAED image of α-MnO2@CNT hybrids, and (h) is the mapping image of α-MnO2@CNT hybrids.

[0032] Figure 3The images show the crystal structure and XPS characterization of each catalyst; (a) is the XRD pattern of each catalyst, (b) is the XPS Mn 2p pattern of each catalyst, (c) is the XPS Mn 3s pattern of each catalyst, (d) is the total XPS pattern of each catalyst, (e) is the XPS O 1s pattern of each catalyst, and (f) is the XPS C 1s pattern of each catalyst.

[0033] Figure 4 The diagram shows the electronic structure of Mn 3d orbitals and the related calculations of periodate adsorption and charge transfer. Among them, (a) is the density of states (DOS) and d-band center of Mn 3d orbitals in α-MnO2 and α-MnO2@CNT, (b) is the adsorption energy and charge density distribution of the interaction between α-MnO2 and PI, (c) is the adsorption energy of the interaction between α-MnO2@CNT and PI, and (d) is the charge density distribution of the interaction between α-MnO2@CNT and PI.

[0034] Figure 5 These are electrochemical characterization diagrams; (a) is the AC impedance spectrum (Nyquist plot) of each catalyst, (b) is the Zeta potential of each catalyst at pH 5.3, (c) is the open circuit potential (OCP) curve of each catalyst electrode after adding PI and mixed pollutants, and (d) is the chronoamperometry (It) curve after adding PI and mixed pollutants.

[0035] Figure 6 These are pollutant degradation performance diagrams; among them, (a) is the degradation diagram of SDZ and RhB mixed pollutants by different catalysts, (b) is the performance radar diagram of different catalysts, (c) is the degradation diagram of mixed pollutants by individual PI, α-MnO2, CNT and α-MnO2@CNT catalysts, (d) is the degradation effect of different sulfonamide antibiotics and RhB mixed systems, (e) is the effect of coexisting ions and humic acid (HA) on the degradation effect, and (f) is the degradation effect of mixed pollutants in different actual water bodies;

[0036] Figure 7 This is a spectrum of active species detection; where (a) is TEMP- 1 EPR spectrum of O2, (b) is DMPO-IO3 • EPR spectra, (c) shows the effect of different quenchers on the degradation of mixed pollutants;

[0037] Figure 8 This is a graph showing the iodine species analysis; where (a) is the distribution of iodine species in the α-MnO2@CNT / PI / SDZ+RhB system, and (b) is the distribution of IO3 species. - Concentration versus reaction time curve;

[0038] Figure 9These are the cycle stability test diagrams; where (a) is the reusability performance diagram of the α-MnO2@CNT / PI system, and (b) is the XPS Mn 2p spectrum of the α-MnO2@CNT hybrid after 4 cycles.

[0039] Figure 10 The effects of different reaction conditions on degradation performance are shown; (a) is the effect of PI concentration on the degradation effect of mixed pollutants, (b) is the effect of catalyst dosage on the degradation effect of mixed pollutants, (c) is the effect of pollutant concentration on the degradation effect of mixed pollutants, (d) is the effect of pH value on the degradation effect of mixed pollutants, (e) is the effect of temperature on the degradation effect of mixed pollutants, and (f) is the effect of Mn 3+ The effect of leaching on the degradation of mixed pollutants, (g) the effect of heavy water (D2O) on the degradation of mixed pollutants, (h) the effect of dissolved oxygen on the degradation of mixed pollutants, and (i) the effect of PME3 concentration changes. 1 O2 intermediate Mn–O • The generation;

[0040] Figure 11 These are the atomic numbers and optimized geometric structure diagrams of the molecules; where (a) is the atomic numbering and optimized geometric structure diagram of the SDZ molecule, and (b) is the atomic numbering and optimized geometric structure diagram of the RhB molecule.

[0041] Figure 12 These are the charge distribution diagrams of molecules; among them, (a) is the highest occupied orbital-lowest unoccupied orbital (HOMO-LUMO) diagram of SDZ molecules, (b) is the electrostatic potential (ESP) diagram of SDZ molecules, (c) is the HOMO-LUMO diagram of RhB molecules, and (d) is the ESP diagram of RhB molecules.

[0042] Figure 13 These are degradation pathway diagrams; where (a) is a schematic diagram of the degradation pathway of SDZ, and (b) is a schematic diagram of the degradation pathway of RhB.

[0043] Figure 14 These are toxicity prediction diagrams; among them, (a) is the developmental toxicity prediction diagram of SDZ and its degradation intermediates, (b) is the mutagenicity prediction diagram of SDZ and its degradation intermediates, (c) is the developmental toxicity prediction diagram of RhB and its degradation intermediates, and (d) is the mutagenicity prediction diagram of RhB and its degradation intermediates.

[0044] Figure 15 This is a graph showing the calculated Gibbs free energy of periodate activation to generate active species; where (a) represents the PI activation to generate 1 The Gibbs free energy curve of O2, (b) shows the generation of IO3 by PI activation. • The Gibbs free energy curve;

[0045] Figure 16 It is generated by PI activation on α-MnO2@CNT 1 O2 and IO3 • A schematic diagram of the reaction pathway. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0047] Example 1: Preparation of orbital-controlled α-MnO2@CNT hybrids

[0048] Step 1, Reagent preparation: Select analytical grade manganese acetate tetrahydrate, potassium permanganate, multi-walled carbon nanotubes (diameter 10~20nm, length 1~5μm, acidified with nitric acid), deionized water, and ethanol;

[0049] Step 2, Mixing and Dispersing: Add 1 mmol manganese acetate tetrahydrate, 1.3 mmol potassium permanganate and 0.08 g carbon nanotubes (10% of the theoretical amount of α-MnO2 generated) to 50 mL of deionized water, and stir magnetically for 30 minutes to form a uniform dispersion.

[0050] Step 3, coprecipitation reaction: Place the dispersion in a 70 ℃ constant temperature water bath and stir magnetically for 3 hours to ensure the reaction proceeds fully;

[0051] Step 4, Separation and Drying: After the reaction is complete, the reaction solution is dried at 8000 r·min. -1 Centrifuge at a speed of 10 min, and wash the precipitate four times each with deionized water and ethanol to remove residual impurities. Then, vacuum dry at 70 °C for 8 h to obtain orbital-controlled α-MnO2@CNT hybrid. Figure 1 ).

[0052] Example 2: Characterization of the structure and electronic properties of the hybrid

[0053] The structure and electronic properties of the α-MnO2@CNT hybrid prepared in Example 1 and the pure phase α-MnO2 and CNT were characterized:

[0054] (1) Characterization by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected electron diffraction (SAED), and elemental mapping: CNTs were confirmed to have a tubular morphology. Figure 2 a), α-MnO2 has a nanoribbon structure ( Figure 2b), CNTs and α-MnO2 form a good interfacial hybrid structure, with a carbon content of 20.6%, and α-MnO2 mainly exposes the (211) and (220) crystal planes (JCPDS No. 44–0141), and C, Mn, and O elements are uniformly distributed ( Figure 2 ch);

[0055] (2) X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterization: further confirming the successful formation of the composite material without altering the crystal structure of individual components. Figure 3 a); Compared to the original α-MnO2, the Mn2p binding energy of the α-MnO2@CNT hybrid exhibits a significant negative shift, indicating an increase in electron density around the Mn species. This can be attributed to the electron-rich π-conjugated system of CNTs, which acts as an electron donor ( Figure 3 b) Mn 3+ / Mn 4+ The ratio increased from 0.71 in α-MnO2 to 0.98 in α-MnO2@CNT, indicating a decrease in the average Mn oxidation state of the hybrid. Figure 3 b); This is supported by the Mn 3s spectrum, where the energy separation increases from 4.81 eV for α-MnO2 to 4.95 eV for the hybrid ( Figure 3 c); Therefore, the enhanced catalytic performance stems from the redistribution of electronic charge around the Mn sites, rather than any crystal phase transition; α-MnO2 and CNT have strong chemical interactions, and the chemical bonds formed between α-MnO2 and CNT can be used to induce electrons to transfer from CNT to the Mn 3d orbitals of α-MnO2 ( Figure 3 All these results indicate that α-MnO2@CNTs can be efficiently prepared with 3d orbitals tuned to Mn through this simple strategy;

[0056] (3) Density functional theory (DFT) calculations: The results show that, compared with pure α-MnO2, the density of electronic states of the Mn 3d orbitals near the Fermi level in the α-MnO2@CNT hybrid is significantly increased, and the center of the Mn d band shifts from -0.296 eV to 0.038 eV (see Figure 4 a)

[0057] (4) Adsorption energy and charge transfer calculation: The adsorption energy of α-MnO2@CNT for PI is -3.18 eV, which is higher than the -2.16 eV of pure phase α-MnO2 (see Figure 4 b、 Figure 4 c) The amount of electrons transferred from the hybrid to PI is 1.212 |e|, which is higher than the 1.097 |e| of the pure phase α-MnO2 (see c). Figure 4 d);

[0058] (5) Electrochemical characterization: Electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance of α-MnO2@CNT (5.0 Ω) was significantly lower than that of pure phase α-MnO2 (7.4 Ω), indicating a significant improvement in interfacial electron transfer efficiency (see Figure 5 a) Zeta potential tests show that the reduction in hybrid electronegativity can decrease the electrostatic repulsion between the surface negative charge and PI anions, further inducing higher oxidant adsorption, which is a necessary prerequisite for further oxidant activation (see...). Figure 5 b); Open-circuit potential (OCP) and chronocurrent (It) tests confirmed a rapid, spontaneous electron transfer process between the hybrid and the PI (see Figure 5 c. Figure 5 d).

[0059] Example 3: Performance test of α-MnO2@CNT hybrid activated PI for degradation of mixed pollutants

[0060] Experimental conditions: 100 mL of a solution containing 10 mg·L⁻¹ was added to a 250 mL cylindrical reactor. -1 Sulfadiazine (SDZ) and 10 mg·L -1 A mixed solution of rhodamine B (RhB) was added with 0.05 g of α-MnO2@CNT hybrid (dosage: 0.5 g·L⁻¹). -1 Add 0.02 mmol PI (0.2 mM), temperature 25 °C, pH=5.3, magnetic stirring speed 250 r·min. -1 Regular sampling and testing are conducted.

[0061] Test results:

[0062] (1) Pollutant degradation efficiency: The removal rate of RhB reached 100.0% after 5 minutes of reaction; the removal rate of SDZ reached 100.0% after 15 minutes of reaction, with degradation rate constants of 2.37 min. -1 (RhB) and 0.44 min -1 (SDZ) (see) Figure 6 (ac); different sulfonamide antibiotics mixed with RhB can all achieve efficient degradation (see Figure 6 d);

[0063] (2) Anti-interference performance: In 10 mM coexisting ions (NO3) - SO4 2- HPO4 2- Cl - ) or 10 mg·L -1 Even in the presence of humic acid (HA), the removal rates of SDZ and RhB remained above 95% (see [link to relevant documentation]). Figure 6 e);

[0064] (3) Actual water body test: In Pearl River water, urban sewage, and tap water, the removal rates of SDZ and RhB remained above 85%, indicating that the system has good practical application potential (see Figure 6 f);

[0065] (4) Detection of active species: Electron paramagnetic resonance (EPR) test showed that there was obvious DMPO-IO3 in the system. • and TEMP- 1 O2 characteristic signal, and IO3 • The signal strength is significantly higher than 1 O2 (see) Figure 7 a, Figure 7 b) Quenching experiments confirmed that IO3 • It is the dominant degradation species. 1 O2 plays a secondary role (see...) Figure 7 c)

[0066] (5) Iodine species analysis: High performance liquid chromatography (HPLC) detection showed that PI decomposition only produces non-toxic IO3. - No HOI, I2 / I3 detected - Toxic iodides, and the addition of SDZ and RhB can promote IO3. - The generation (see) Figure 8 a, Figure 8 b)

[0067] (6) Cyclic stability: After the catalyst was recycled 4 times, the removal rates of SDZ and RhB did not change significantly, and the Mn 2p XPS spectrum of the hybrid after the reaction showed that its chemical state was stable (see Figure 9 a, Figure 9 b).

[0068] Example 4: Performance Comparison of Different Catalysts

[0069] Using the same experimental conditions as in Example 3, and with pure-phase α-MnO2 and CNT as catalysts, their performance in activating PI degradation of SDZ and RhB was tested. The results are as follows:

[0070] (1) Pure phase α-MnO2: After 30 minutes of reaction, the removal rate of SDZ was 52.4% (of which the adsorption rate was 9.6% and the degradation rate was 42.8%), the removal rate of RhB was 100.0%, and the removal rate constants were 0.07 min. -1 and 2.37 min -1 Around, active species 1 O2 is the main component (see O2) Figure 6 ac);

[0071] (2) CNT: After 30 minutes of reaction, the removal rate of SDZ was 69.4% (of which the adsorption rate was 44.8% and the degradation rate was 24.6%), the removal rate of RhB was 100.0%, and the removal rate constants were 0.21 min. -1 and 2.37 min -1 Around 1000 species, with active species in IO3 • The main component is [specifically], but the overall activity is low (see [reference]). Figure 6 ac);

[0072] (3) The α-MnO2@CNT hybrid of the present invention has a significantly higher degradation efficiency and rate than the two catalysts mentioned above (with an adsorption rate of 29.7% and a degradation rate of 70.3%), and the active species are mainly IO3. • The main focus is on demonstrating a clear synergistic effect (see...) Figure 6 ac).

[0073] Example 5: Effect of different reaction conditions on degradation performance

[0074] Using the hybrid prepared in Example 1 as a catalyst, and employing the same experimental system as in Example 3, the effects of different reaction conditions were investigated:

[0075] (1) PI concentration: In the range of 0.1~0.2 mM, the degradation efficiency of pollutants increases significantly with the increase of PI concentration; when the PI concentration exceeds 0.2 mM, the degradation efficiency decreases slightly, mainly due to the free radical quenching effect and PI diffusion limitation (see Figure 10 a)

[0076] (2) Catalyst dosage: The catalyst dosage is 0.1~0.5 g·L -1 Within the specified range, the degradation efficiency increases with increasing dosage; however, when the dosage exceeds 0.5 g·L⁻¹, the degradation efficiency decreases further. -1 At this point, the degradation efficiency tends to stabilize, and diminishing marginal returns occur (see...). Figure 10 b)

[0077] (3) Pollutant concentration: The pollutant concentration is between 10 and 30 mg·L. -1 Within the specified range, the degradation rate gradually decreased with increasing concentration, consistent with concentration-dependent kinetic characteristics (see [reference needed]). Figure 10 c)

[0078] (4) pH value: The degradation efficiency remained above 95% in the pH range of 3.3 to 5.3; when the pH was 7.3 and 9.3, the degradation efficiency still reached above 87.6%, indicating that the system has good pH adaptability (see Figure 10 d);

[0079] (5) Temperature: Increased temperature can significantly increase the degradation rate, indicating that the reaction is endothermic. In practical applications, the reaction time can be adjusted appropriately according to the water temperature (see Figure 10 e);

[0080] (6) Other influencing factors: Mn 3+ The dissolution rate is extremely low (0.051 mg·L⁻¹). -1 ), had no significant effect on PI-activated degradation of mixed pollutants (see Figure 10 f); Heavy water (D2O) can improve degradation performance to some extent, further indicating that the system contains... 1 The generation of O2 (see) Figure 10 g); Dissolved oxygen has a relatively small impact on degradation performance (see g); Figure 10 h); PMe3 detection confirms the system 1 O2 intermediate Mn–O • The generation (see) Figure 10 i).

[0081] Example 6: Degradation intermediates and pathway analysis

[0082] Degradation intermediates of SDZ and RhB were detected by LC-MS, and DFT calculations were performed (see [link to DFT calculation] for atom numbering, geometric optimization, and charge distribution of SDZ and RhB molecules). Figure 11 a, Figure 11 b、 Figure 12 (ad), and proposes its degradation pathway (see ad). Figure 13 a, Figure 13 b): SDZ is mainly degraded through processes such as amino oxidation, benzene ring opening, and sulfonamide bond cleavage, while RhB is mainly degraded through processes such as deethylation, chromophore cleavage, and benzene ring opening; toxicity predictions of degradation intermediates show that as degradation progresses, the developmental toxicity and mutagenicity of the pollutants significantly decrease (see...). Figure 14 ad); PI activation generates IO3 • and 1 The reaction pathway and Gibbs free energy curve of O2 are shown in [reference needed]. Figure 15 a, Figure 15 b and Figure 16 .

[0083] As can be seen from the above embodiments, through the preparation of orbit-controlled α-MnO2@CNT hybrids, characterization of the structure and electronic properties of the hybrids, performance testing of α-MnO2@CNT hybrids activating PI to degrade mixed pollutants, performance comparison of different catalysts, influence of different reaction conditions on degradation performance, and analysis of degradation intermediates and pathways, this invention achieves efficient remediation of complex water bodies. Furthermore, the preparation process is simple and low-cost, the catalyst exhibits good stability and strong anti-interference ability, has a wide range of applications, and does not generate toxic iodides. This provides methodological and theoretical support for the application of orbit-controlled catalyst-activated periodate technology in the remediation of complex water bodies.

[0084] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An orbital-controlled α-MnO2@CNT hybrid, characterized in that, The hybrid was prepared by a one-step co-precipitation method, with α-MnO2 nanoribbons as the active component and carbon nanotubes (CNTs) as the electron reservoir. CNTs and α-MnO2 form an interfacial hybrid structure, which regulates the electronic density of states of the Mn 3d orbitals, causing the center of the Mn d band to shift from -0.296 eV to 0.038 eV.

2. The orbital-controlled α-MnO2@CNT hybrid according to claim 1, characterized in that, The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10~20 nm and a length of 1~5 μm, and are treated with nitric acid.

3. A method for preparing the orbital-controlled α-MnO2@CNT hybrid as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1, Reagent preparation: Select manganese acetate tetrahydrate ((CH3COO)2Mn·4H2O), potassium permanganate (KMnO4), carbon nanotubes and other analytical grade reagents. All reagents can be used directly without further purification. Step 2, Mixing and Dispersion: Add manganese acetate tetrahydrate, potassium permanganate, and carbon nanotubes to deionized water and stir until homogeneous to form a dispersion; wherein the molar ratio of manganese acetate tetrahydrate to potassium permanganate is 1:(1.2~1.5), and the amount of carbon nanotubes added is 5%~15% of the theoretical amount of α-MnO2 generated; Step 3, coprecipitation reaction: Place the dispersion in a constant temperature water bath at 60~80 ℃ and stir continuously for 2~4 hours to ensure uniform reaction. Step 4, Separation and Drying: After the reaction is completed, the reaction solution is centrifuged and separated. The resulting precipitate is washed with deionized water and ethanol 3 to 5 times to remove impurities. Then, it is vacuum dried at 60 to 80 °C for 6 to 12 hours to obtain orbital-controlled α-MnO2@CNT hybrid.

4. The preparation method according to claim 3, characterized in that, In step 3, the temperature of the constant temperature water bath is 70 ℃ and the reaction time is 3 hours; in step 4, the temperature of vacuum drying is 70 ℃ and the drying time is 8 hours.

5. The orbital-controlled α-MnO2@CNT hybrid as described in claim 1 or 2, in the selective generation of IO3 from periodate. • The application of this is characterized by, The hybrid compound was used as a catalyst and added to water containing periodate and mixed pollutants. Under conditions of 20–30 °C and pH 3.3–9.3, it was used to selectively generate IO3 from periodate. • Main, 1 O2 is a secondary active species, enabling the simultaneous degradation of mixed pollutants.

6. The application according to claim 5, characterized in that, The mixed contaminant is a mixture of sulfonamide antibiotics and rhodamine B (RhB), wherein the sulfonamide antibiotics include one or more of sulfadiazine, sulfapyridine, and sulfamethoxazole.

7. The application according to claim 5, characterized in that, The catalyst is added at a rate of 0.3~0.7 g·L. -1 The concentration of periodate was 0.1–0.3 mM, and the concentration of each component in the mixed pollutants was 5–20 mg·L⁻¹. -1 .

8. The application according to claim 5, characterized in that, The reaction conditions were: temperature 20–30 °C, pH 3.3–9.3, and stirring rate 200–300 r·min. -1 The reaction time is 5-30 minutes, and no toxic iodides (HOI, I2 / I3) are produced during the reaction. - ) is generated, producing only non-toxic IO3. - .

9. The application according to claim 7, characterized in that, The catalyst dosage is 0.5 g·L. -1 The concentration of periodate was 0.2 mM, and the concentration of each component in the mixed pollutants was 10 mg·L⁻¹. -1 .

10. The application according to claim 8, characterized in that, The reaction temperature was 25 ℃ and the pH was 5.3.

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