CN115069265A - Preparation and application of active carbon fiber loaded cobalt-manganese bimetallic oxide catalyst - Google Patents

Preparation and application of active carbon fiber loaded cobalt-manganese bimetallic oxide catalyst Download PDF

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CN115069265A
CN115069265A CN202210805960.XA CN202210805960A CN115069265A CN 115069265 A CN115069265 A CN 115069265A CN 202210805960 A CN202210805960 A CN 202210805960A CN 115069265 A CN115069265 A CN 115069265A
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carbon fiber
acfs
composite material
catalyst
activated carbon
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牛怀远
付雯馨
牛承岗
胡琦瑶
李忠武
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Hunan University
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/889Manganese, technetium or rhenium
    • B01J23/8892Manganese
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002Mixed oxides other than spinels, e.g. perovskite
    • B01J35/40
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02Impregnation, coating or precipitation
    • B01J37/03Precipitation; Co-precipitation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08Heat treatment
    • B01J37/10Heat treatment in the presence of water, e.g. steam
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/722Oxidation by peroxides
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/725Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/30Organic compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/30Organic compounds
    • C02F2101/34Organic compounds containing oxygen
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/30Organic compounds
    • C02F2101/36Organic compounds containing halogen
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/30Organic compounds
    • C02F2101/38Organic compounds containing nitrogen
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00Use of specific compounds during water treatment
    • C02F2305/02Specific form of oxidant
    • C02F2305/023Reactive oxygen species, singlet oxygen, OH radical

Abstract

The invention discloses a catalyst prepared from Co 3 O 4 The @ ACFs is taken as a precursor, and the Co with high efficiency and easy recovery is synthesized by coprecipitation 3 O 4 ‑Mn 3 O 4 @ ACFs nanocatalysts. Activated carbon fiberThe nano-particles have a mesoporous structure, a high specific surface area and rich functional groups, can prevent the aggregation of the cobalt/manganese nano-particles, and promote the uniform distribution of active metals. The strong interaction force of Mn-Co-C and Co-C-Mn exists between the manganese cobalt oxide and the active carbon fiber, and the loss of metal ions can be reduced. The synergistic effect between the manganese cobalt oxide and the active carbon fiber can promote Co 2+ And Co 3+ The capacity of activating the persulfate is obviously improved by cyclic conversion. Prepared Co 3 O 4 ‑Mn 3 O 4 The degradation rate of the @ ACFs catalyst on Ciprofloxacin (CIP) can reach 96.79%, and the catalyst is easy to separate from a solution and has good stability and reusability.

Description

Preparation and application of active carbon fiber loaded cobalt-manganese bimetallic oxide catalyst
Technical Field
The invention belongs to the technical field of advanced oxidation, and mainly relates to coprecipitation preparation and application of an active carbon fiber loaded cobalt-manganese bimetallic oxide composite catalyst.
Background
Antibiotics have been widely used since their discovery, and their residues and derivatives inevitably pose a significant threat to human health and ecological safety. Ciprofloxacin (CIP), a representative of fluoroquinolone antibiotics, has become one of the most commonly detected antibiotics among sewage, surface water, ground water, and even drinkable antibiotics. However, semi-permanent overexistence of CIP in the environment will increase antibiotic resistance, exacerbating the health threat to some people. Conventional treatment methods such as physical (adsorption) and chemical (precipitation, flocculation) methods have very limited efficiency in degrading CIP and may generate by-products during the treatment process to cause secondary pollution. Therefore, there is a strong need to develop an effective method for removing CIP in an aqueous environment to prevent the CIP from causing greater harm to the environment and human health.
Because strong oxidizing radicals are generated in situ, persulfate-based Advanced Oxidation Processes (AOPs) can effectively degrade a variety of inert organic pollutants and are widely considered as alternative technologies for water treatment and soil remediation. Potassium hydrogen Persulfate (PMS), a member of the persulfate salts, exhibits good stability, high redox potential (E) 0 1.75V), wide pH adaptation and high selectivity for organic contaminants.
Furthermore, PMS is susceptible to one-electron reduction, where cleavage of the peroxide bond can generate an active radical species, i.e., SO 4 And. OH. Furthermore, in the non-radical pathway, PMS is more likely to produce O 2 ·- And 1 O 2
studies have shown that activated PMS by heat, uv, ultrasound, carbon-based materials and transition metal ions can generate Reactive Oxygen Species (ROS). Wherein the transition metal Co 2+ The activation performance of PMS activation through the one-electron oxidation pathway is highest. However, with Co 2+ The practical use of related homogeneous PMS catalysts is limited by the potential for toxic hazards and limited environmental tolerance. In addition, the metallic cobalt particles also have the problems of easy agglomeration, fast consumption, slow regeneration, easy consumption of Co ions in water environment and the like. To improve the above situation, in this study, cobalt oxide was dispersed on a non-toxic and harmless carbon-based functional support (activated carbon fiber) and combined with another active metal manganese oxide. Cobalt oxide nanoparticles having higher stability and smaller particle size than common cobalt oxide have attracted a great deal of attention in pollutant treatment. Wherein Co 3 O 4 Has two oxidation state cobalt species (i.e. Co) in the crystal lattice structure of the mineral spinel II And Co III ) An efficient reversible redox cycle can be performed. Compared with other carbon materials, the Activated Carbon Fibers (ACFs) are not only loose and porous and convenient to recover, but also rich in oxygen-containing functional groups and can further promote the generation of ROS. More importantly, due to the advantages of the ACFs, the Co-ACFs composite material shows better degradation performance than most reported heterogeneous Co catalysts, so that the adsorption capacity of the material can be improved, and the Co-ACFs composite material can be used as an electron donor to accelerate Co II /Co III And (6) circulating. Notably, OH has been shown to be the primary free radical in the Co-ACF/PMS system. In addition, spinel-structured Mn prepared by simple hydrothermal method 3 O 4 Also exhibits superior Co-over-Co in the presence of PMS 3 O 4 The catalytic activity of (3).
Thus, in the present study, nanoscale synthetic materials (Co) containing active materials were synthesized by a simple Co-precipitation method at relatively low temperatures in a non-covalent and covalent bonding manner 3 O 4 -Mn 3 O 4 @ ACFs). Activity deviceThe carbon fiber has high specific surface area and strong adsorption capacity, simultaneously has rich chemical functional groups, shows strong activity, can improve the stability and the dispersibility of the nano manganese cobalt oxide material, and can increase the contact area and the retention time of pollutants on the surface of the material. The metal oxide nano material dispersed on the active carbon fiber can prevent agglomeration phenomenon in the growth process, thereby improving the catalytic activity and the catalytic efficiency. Meanwhile, strong covalent bond interaction of Mn-Co-C and Co-C-Mn exists between the manganese cobalt oxide and the activated carbon fiber, so that loss of metal ions can be reduced. The synergistic effect between manganese cobalt oxide and activated carbon fiber can also promote Co 2+ And Co 3+ The cyclic conversion of the composite material obviously improves the capability of the composite material for activating persulfate, and has the potential of practical large-scale application.
Disclosure of Invention
In order to overcome the defects of the prior art and improve the defects, the invention synthesizes Co by adopting a hydrothermal reaction 3 O 4 @ ACFs precursor, then coprecipitating in potassium permanganate solution to grow Co 3 O 4 -Mn 3 O 4 The @ ACFs nano composite catalyst is applied to activating persulfate to degrade ciprofloxacin pollutants.
In order to solve the problems, the invention is realized by the following technical scheme:
the pretreatment of the activated carbon fiber comprises the following steps:
s1, cutting the activated carbon fiber into small pieces of 2cm multiplied by 2cm, placing the small pieces in ultrapure ion removal water, and cleaning until no obvious floating black impurities exist;
s2, soaking the activated carbon fiber in 4mol/L nitric acid solution for 24 hours;
s3, washing the activated carbon fiber by 4% hydrochloric acid in a water bath at 50 ℃ for 40min in an oscillating way;
s4, collecting the material, washing with deionized water until the pH of the washing liquid is neutral, ultrasonically treating with deionized water for 30min, and drying at 80 ℃ for 12 h.
Co 3 O 4 The synthesis method of the @ ACFs seed precursor comprises the following steps:
s5, weighing a mixture of cobalt nitrate, ammonium fluoride and urea, dissolving in aqueous ethanol, and fully stirring to form a mixed solution;
s6, taking the activated carbon fiber as a carbon carrier, and soaking 1.0g of the activated carbon fiber in the mixed solution. The particles are uniformly distributed in the activated carbon fiber by ultrasonic treatment for 1h, and the material is transferred to a hydrothermal reactor. Keeping the temperature at 100 ℃ for 12h, and naturally cooling after reaction;
s7, washing the composite material with distilled water and absolute ethyl alcohol under ultrasonic waves for three to five times, and placing the composite material in an oven for vacuum drying;
s8, placing the hydrothermal product in a tubular calcining furnace, and heating at the speed of 5 ℃/min in N 2 Heating to 300 ℃ under protection and keeping for 3 hours to synthesize Co 3 O 4 @ ACFs precursor seed composites.
Co 3 O 4 -Mn 3 O 4 The synthesis method of the @ ACFs composite material comprises the following steps:
s9, weighing KMnO 4 Dissolving in absolute ethyl alcohol, and fully stirring for 4 hours;
s10, adding the composite material into a potassium permanganate solution, continuing stirring for 1h, and performing ultrasonic treatment for 1h to uniformly disperse the particles in Co 3 O 4 @ ACFs composite;
s11, placing the mixture in a hydrothermal reaction kettle, heating for 12 hours at 100 ℃ to enable the mixture to undergo oxidation-reduction reaction to grow manganese oxide, and naturally cooling the composite material after reaction;
s12, ultrasonically cleaning the composite material by using distilled water and absolute ethyl alcohol respectively for three to four times, wherein each time is 10min, and then drying the composite material in a vacuum drying oven;
s13, putting the obtained composite material in a tube furnace N 2 And (3) processing for 90min at 300 ℃ under protection to obtain a compound after heat treatment, and finally obtaining the catalytic material.
The preparation scheme designed by the invention firstly carries out simple hydrothermal reaction to obtain Co 3 O 4 The preparation method comprises the following steps of @ ACFs precursor, then carrying out low-temperature calcination, and carrying out coprecipitation reaction to obtain the composite material. The related raw materials are easy to obtain, the experimental operation is simple, and the conditions are easyAnd what is important is that the synthesized material is stable, green, environment-friendly and pollution-free.
As a general technical concept, the invention also provides the practical application of the catalytic material in degrading antibiotics in wastewater, wherein the antibiotics are ciprofloxacin, and the preferable process is as follows:
(1) co to be prepared 3 O 4 -Mn 3 O 4 @ ACFs catalyst was placed in a volume of 100mL 10mg L -1 Stirring and adsorbing the ciprofloxacin solution for 2 hours at room temperature under the condition of not adding PMS;
(2) and (3) adding PMS under the same conditions as in the step (1) to realize the degradation of pollutants by activating PMS.
Co prepared as described above 3 O 4 -Mn 3 O 4 The addition amount of the @ ACFs catalyst is that the catalytic material is added in 0.5g L per liter of the antibiotic-containing wastewater -1 (ii) a The concentration of the ciprofloxacin in the wastewater is 10mg L -1 (ii) a The prepared Co 3 O 4 -Mn 3 O 4 In the application of the @ ACFs catalyst in the degradation of antibiotics in wastewater by activating PMS, the stirring time is 2 h; the amount of PMS added is 0.20g L added in each liter of the wastewater containing the antibiotics -1 (ii) a The catalytic degradation time is 2 h.
The advanced oxidation process based on sulfate radical is an effective method for repairing environmental organic pollution, and the metal-based and carbon-based catalysts can efficiently activate persulfate to degrade organic pollutants. There are still a number of problems to be solved, especially in terms of metal ion leaching, stability and reusability. Therefore, the invention adopts a simple process to prepare Co with good stability and excellent catalytic performance 3 O 4 -Mn 3 O 4 The @ ACFs composite material catalyst is used as a green catalyst for degrading quinolone antibiotics represented by ciprofloxacin. Mn is used as the main component of the invention 3 O 4 -Co 3 O 4 And the bimetallic oxide-organic carbon framework composite material is prepared by adopting a more environment-friendly coprecipitation and hydrothermal method on the basis of activated carbon fiber. Co 3 O 4 The @ ACFs were used as seeds where oxides of manganese grewOn the top of the seed. The composite material has high catalytic oxidant activity and good chemical reaction stability, is easy to recycle after sewage treatment, and has excellent degradation efficiency when used for ciprofloxacin. Mn 3 O 4 -Co 3 O 4 The @ ACFs material contains active cobalt and manganese and the synergistic effect of the active cobalt and the manganese plays a key role in the process of activating PMS to degrade CIP. The composite material has multiple catalytic sites, excellent stability and easy recovery performance, and can be used for catalyzing PMS to remove pollutants in wastewater.
Compared with the traditional technology, the invention has the advantages that:
the ideal catalytic oxidation process must be efficient, low toxicity, low cost, and this is also a major challenge for wastewater remediation. The PMS activator Co is successfully synthesized by the low-temperature coprecipitation method 3 O 4 -Mn 3 O 4 The @ ACFs composite material can effectively degrade CIP which is a representative of quinolone antibiotics. Co 3 O 4 -Mn 3 O 4 @ ACFs/PMS allowed 81.42% CIP degradation to be completed in 15 minutes and complete degradation to be achieved in 120 minutes. Composite material O production by PMS activation 2 · - , 1 O 2 ,SO 4 · - And OH, free radical quenching experiments and ESR analysis showed that OH and O 2 · - Plays a key role in the degradation process. The synergy between Co, Mn and ACFs further aids in the low toxicity degradation of CIP. After three consecutive cycles of the experiment, high catalytic activity was maintained. Because the activated carbon fiber has stronger adsorption performance, the composite material has Co on the surface 3 O 4 -Mn 3 O 4 Has good magnetic advantages and has good adsorption effect. And strong adsorption performance is the basic potential foundation of the composite material applied to soil or ultrafiltration membranes in the future. The loss of the composite material immobilized by the composite material is almost zero, and the composite material immobilized by the composite material has the advantages of difficult migration and easy recovery. Meanwhile, the preparation of the material has the advantages of easily obtained raw materials, high stability of synthetic materials, low energy consumption, high synthesis rate, simple process, easily controlled conditions, environmental protection, no secondary pollution and the like, and is suitable for continuous large-scale production. Thus, the deviceThe Co3O4-Mn3O4@ ACFs composite material has great potential in the aspects of expanding application scenes (medical wastewater treatment, sewage treatment plant application, heavy metal adsorption in soil and underground water in-situ remediation). This study provides a new concept for designing efficient, economical, green pollutant degradation processes and their application in future wastewater treatment.
In summary, the invention has the advantages that: (1) metal-metal synergy of the bimetallic surface during the catalytic reaction increases the Charge Transfer Efficiency (CTE); (2) the material has richer chemical bonds due to low-temperature loading; (3) the carbon carrier enhances the stability of the nano composite material and further improves the catalytic activity; (4) generating organic free radicals, including SO 4 · - ,·OH,O 2 · - And 1 O 2 (ii) a (5) Easy to recover and has great application potential.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
Drawings
FIG. 1 shows Co in example 1 of the present invention 3 O 4 -Mn 3 O 4 The XRD diffraction pattern of @ ACFs.
FIG. 2 shows Co in example 1 of the present invention 3 O 4 -Mn 3 O 4 XPS plots for @ ACFs. Wherein B, C, D and E diagrams are XPS diagrams for carbon atoms, oxygen atoms, manganese atoms, and cobalt atoms, respectively.
FIG. 3 shows Co of example 1 according to the present invention 3 O 4 -Mn 3 O 4 SEM and TEM electron microscopy analysis of @ ACFs.
FIG. 4 shows Co in example 1 of the present invention 3 O 4 -Mn 3 O 4 Graph of time-adsorption efficiency of @ ACFs versus CIP.
FIG. 5 shows Co obtained in example 1 of the present invention 3 O 4 -Mn 3 O 4 A time-degradation efficiency relation graph of the @ ACFs catalyst for activating PMS to degrade CIP.
FIG. 6 shows Co in example 3 of the present invention 3 O 4 -Mn 3 O 4 And (3) a corresponding cycle number-degradation efficiency graph when the @ ACFs catalyst circularly degrades the CIP wastewater.
Detailed Description
The invention is described in more detail below with reference to examples and the accompanying drawings, but the invention is not limited thereto.
The materials and equipment used in the following examples are commercially available. In the examples of the present invention, unless otherwise specified, the adopted process is a conventional process, the adopted equipment is conventional equipment, and the obtained data are average values of three or more repeated experiments.
Example 1
Co of the invention 3 O 4 -Mn 3 O 4 The synthesis method of the @ ACFs catalyst comprises the following steps:
cutting the activated carbon fiber into small pieces of 2cm multiplied by 2cm, placing the small pieces in ultrapure ion water, and cleaning until no obvious floating black impurities exist. Soaking the activated carbon fiber in 4mol/L nitric acid solution for 24h, and then shaking and washing the activated carbon fiber for 40min by using 4% hydrochloric acid in water bath at 50 ℃. The material was then collected, washed with deionized water until the pH of the wash was neutral, sonicated with deionized water for 30min, and dried at 80 ℃ for 12 h.
Preparing a cobalt nitrate solution. A mixture of cobalt nitrate (0.2mmol), ammonium fluoride (0.1mmol) and urea (0.2mmol) was weighed out, dissolved in 100ml of aqueous ethanol and mixed well for 4h to form a mixed solution. Then, the activated carbon fiber was used as a carbon carrier, and 1.0g of the activated carbon fiber was soaked in the mixed solution. The particles are uniformly distributed in the activated carbon fiber by ultrasonic treatment for 1h, and the material is transferred to a hydrothermal reactor. After keeping at 100 ℃ for 12h, naturally cooling. The composite material was washed three to five times with distilled water and absolute ethanol under ultrasonic waves, and placed in an oven for vacuum drying. Finally, the hydrothermal product was placed in a tubular calciner at a rate of 5 ℃/min under N 2 Heating to 300 ℃ under protection and keeping for 3 hours to synthesize Co 3 O 4 @ ACFs precursor seed composites.
Dissolving to obtain potassium permanganate solution. Weighing KMnO 4 0.1g, dissolved in 100ml absolute ethyl alcohol, fully stirring for 4 h. Adding the composite material into potassium permanganate solution, continuously stirring for 1h, and performing ultrasonic treatment for 1h to uniformly disperse the particles in Co 3 O 4 @ ACFs composite materials. And then placing the mixture in a hydrothermal reaction kettle, heating for 12 hours at 100 ℃ to enable the mixture to undergo self redox reaction to grow manganese oxide, and naturally cooling the composite material after reaction. The composite material is respectively washed for three to four times by distilled water and absolute ethyl alcohol in the ultrasonic washing process, each time is 10min, and then the composite material is placed in a vacuum drying oven to be dried. The obtained composite material is put in a tube furnace N 2 Processing at 300 deg.C for 90min under protection to obtain calcined composite, and finally synthesizing Co 3 O 4 - Mn 3 O 4 @ ACFs composite materials.
Experimental example 1
Co of example 1 3 O 4 -Mn 3 O 4 XRD analysis was performed on @ ACFs, and the results are shown in FIG. 1.
Obtaining Co by XRD 3 O 4 -Mn 3 O 4 Phase, crystallinity and composition information of @ ACFs. The XRD patterns showed diffraction peaks for the four materials, respectively. As shown in fig. 1a, the purple curve a shows diffraction intensity, and five typical diffraction peaks appear at 31.3 °, 36.8 °,44.6 °, 59.5 ° and 65.1 ° 2 θ, which are assigned to Co 3 O 4 Typical (220), (311), (400), (511) and (440) planes of (A), which are of Co 3 O 4 Dominant face of feature (JCPDS # 09-0418). In particular, other phases could be detected, for example, diffraction peaks from 2 θ ═ 28 ° to (260) were consistent with cubic CoOOH (JCPDS #26-0480), indicating that the calcined product obtained at low temperature was not pure crystalline, with more abundant chemical bonds. Curve b, having peaks at 28.9 °, 32.5 °, 36.2 °, 38.0 °,44.6 °, 50.9 °, 58.8 ° and 60.0 °, closely matches the (112), (103), (211), (004), (220), (105), (321) and (224) facets of the quadrangular prism. Results are reflected with cubic phase Mn 3 O 4 The standard data (JCPDS #01-1127) closely matched and revealed that the resulting catalyst had the expected crystallinity. Likewise, the green curve c not only represents Co 3 O 4 And Mn 3 O 4 And shows a similarity to MnCo 2 O 4 The unique diffraction angles of the bimetallic oxides, having 2 theta values of 30.54 DEG, 35.99 DEG and 63.62 DEG, are distributed over MnCo 2 O 4 The (220), (311), and (440) lattice planes, which closely match the data in the JCPDS #23-1237 standard. As shown in FIG. 1d, Co 3 O 4 -Mn 3 O 4 Diffraction patterns of @ ACFs with Co 3 O 4 -Mn 3 O 4 The composites of (a) were very consistent, indicating that Co is present 3 O 4 -Mn 3 O 4 @ ACFs as Co 3 O 4 And Mn 3 O 4 The composite of (2) has been successfully synthesized.
Experimental example 2
XPS shows Co 3 O 4 -Mn 3 O 4 The true chemical and electronic states of Co and Mn in @ ACFs. As shown in fig. 2, XPS detection spectrum showed that the prepared composite material was mainly composed of Co, Mn, C and O, and no other elements were identified. In fig. 2b, the C1 s spectrum consists of two peaks. C-C/C ═ C (284.8 eV), C-O (286.3 eV). In addition, the signal peak of C shifts to some extent (-0.4eV), which means that C ═ O-transition metal covalent bonds are formed in the composite material. Two distinct peaks were found at 531.1eV and 532.7eV, which should be attributed to the oxygen vacancy (O) v ) And adsorbed O 2 Is present. As predicted, the XPS spectrum of Co 2p shows two peaks at 779.0eV and 785.5eV, corresponding to Co respectively 2+ And Co 3+ (FIG. 2 e). Likewise, the Mn 2p spectrum of the composite (FIG. 2d) exhibits a typical 2p 3/2 And 2p 1/2 . High resolution Mn 2p by fitting XPS peaks to Gaussian distribution 3/2 The spectrum may be divided into two or three portions. These peaks are around 641.2 and 642.2eV, and are identified as Mn, respectively 2+ And Mn 3+ In which the difference between peaks was 11.6 eV. In addition, Mn is based on the corresponding peak area 3+ And Mn 2+ Is evaluated as 2:1, which corresponds to Mn 3 O 4 The feature in (1). Another 643.7eV peak in FIG. 2d represents Mn 4+ . Notably, the Co peak of XPSTo a higher binding energy (+4eV) due to strong electron interactions between Mn, O and Co. Thus, XPS analysis demonstrates that the strong Co-existence of Co and Mn with the carbon backbone and various oxidation states can promote the efficiency of the electron and oxygen transfer process and reduce metal ions, which can promote CIP degradation.
Experimental example 3
Co of example 1 3 O 4 -Mn 3 O 4 @ ACFs for SEM and TEM electron microscopy analysis. By reviewing SEM and TEM images, the morphology and microstructure of the composite Co3O4-Mn3O4@ ACFs were explored. The SEM images in fig. 3(a-d) show that the tubes are composed of carbon fibers. Based on XRD and XPS analysis, these crystalline particles distributed on the surface of ACFs were identified as Co 3 O 4 And Mn 3 O 4 . Co exhibiting plate-like structure in the nanostructure using SEM analysis 3 O 4 -Mn 3 O 4 The presence of @ ACFs is not obvious. Thus, TEM measurements are used to further explain Co 3 O 4 And Mn 3 O 4 Morphology and growth on carbon fibers. The TEM images in FIG. 3(c-d) show that the material surface has a particulate nanoparticle structure. Meanwhile, ACF as a carbon support seems to induce separation of metal oxides. The high density of nanoparticles is not uniformly distributed on the surface. Co 3 O 4 And Mn 3 O 4 The particles have a crystal diameter of about 10-50 nm, and a moderate particle size may be beneficial for stable and efficient degradation performance.
Example 4
Prepared Co 3 O 4 -Mn 3 O 4 The application of the @ ACFs composite material catalyst activated PMS to degradation of antibiotics in wastewater mainly comprises the following steps:
weighing ACF and Co 3 O 4 ,Mn 3 O 4 ,Co 3 O 4 -Mn 3 O 4 And Co 3 O 4 -Mn 3 O 4 0.05g of @ ACFs (example 1) were added to 100mL of 10mg of L -1 The Ciprofloxacin (CIP) wastewater is magnetically stirred for 2 hours without PMSSo as to achieve the adsorption balance; under the same condition, PMS is added, and the mixture is magnetically stirred to react for 2 hours, so that the aim of degrading the antibiotics in the wastewater is fulfilled.
In the process of catalytic reaction, ciprofloxacin liquid is extracted into a centrifuge tube filled with 1mL of methanol at certain intervals, the characteristic peak value of CIP in the solution is measured by an ultraviolet-visible spectrophotometer, and the degradation efficiency is calculated. The prepared catalytic materials were subjected to the same procedure, and the degradation efficiency was calculated.
FIG. 4 is ACF, Co 3 O 4 ,Mn 3 O 4 ,Co 3 O 4 -Mn 3 O 4 And Co 3 O 4 -Mn 3 O 4 @ ACFs (example 1) time-adsorption efficiency graph for CIP without PMS addition. FIG. 5 is ACF, Co 3 O 4 , Mn 3 O 4 ,Co 3 O 4 -Mn 3 O 4 And Co 3 O 4 -Mn 3 O 4 Graphs relating time-degradation efficiency of @ ACFs (example 1) for CIP with PMS addition, in FIGS. 4 and 5, C t Representing CIP concentration after degradation, C 0 The initial concentration of CIP is indicated. As can be seen from fig. 4 and 5:
co obtained in example 1 of the present invention 3 O 4 -Mn 3 O 4 The degrading efficiency of the @ ACFs to the CIP after the catalytic reaction is 30min is 80%, and the degrading efficiency to the CIP after the catalytic reaction is 120min is 95%.
Comparative Co of the invention 3 O 4 -Mn 3 O 4 The degradation efficiency of the catalytic material to CIP after 120min of catalytic reaction is 60%.
Comparative Co of the invention 3 O 4 And Mn 3 O 4 The degradation efficiency of the catalyst catalytic material to CIP after 120min of catalytic reaction is 30-40%.
In the absence of PMS, the composite was effective only for adsorption of CIP in the control experiment. Due to the unique heterogeneous nanostructure, bimetallic oxides exhibit better adsorption performance than monometallic oxides, with an improvement effect greater than the sum of the monomer adsorption amounts. This may be due toThe presence of more abundant metallic bonds in the bimetallic oxide, except for Co 3 O 4 And Mn 3 O 4 Besides the bond energy between the monomers, there are Co and Mn monomers and manganese cobaltate. Meanwhile, ACF possesses a large number of active sites, and exhibits strong adsorption capacity due to its larger pore volume occupancy and higher micropore volume. As described in fig. 4, although the ACF is supported by the bimetal oxide, its adsorption performance may not be affected. This phenomenon indicates that the adsorption process does not depend solely on surface area. Through XPS data analysis, chemical bonds of C-transition metals or C-O-transition metals may exist between the bimetallic oxides and the ACFs, which positively promote the adsorption capacity.
FIG. 5 shows Co 3 O 4 -Mn 3 O 4 Composite properties of @ ACFs on CIP degradation. Experiments prove that the self-degradation capability of CIP and PMS is very weak if the prepared composite material is not involved. Only 3% of CIP was degraded by PMS within 120 minutes, revealing that PMS was difficult to activate without external catalysis. Likewise, a single metal oxide can only degrade 30% -40% of the CIP in 120 minutes. Also, ACF exhibits relatively poor degradation properties. After coupling with Co-Mn bimetallic oxides, Co 3 O 4 -Mn 3 O 4 the/PMS can exhibit a great enhancement, which can reduce CIP by about 60% in 120 minutes. However, with Co 3 O 4 -Mn 3 O 4 The efficiency of the bimetallic oxide/PMS degradation was lower compared to @ ACFs/PMS (80% in 30min, 95% in 120 min). According to a series of control tests, the effective catalytically active components of the composite material can be investigated.
Co 3 O 4 Has degradation efficiency higher than that of Mn 3 O 4 Showing that Co II And Co III The interface is the main catalytically active component. The catalytic activity of the bimetal oxidation compound is greatly improved, which shows that Mn 3 O 4 -Co 3 O 4 Has potential synergistic effect. Except for Mn 3 O 4 And Co 3 O 4 In addition to the metallic bonds present per se, in Mn 3 O 4 -Co 3 O 4 Between also forms MnCo 2 O 4 . Meanwhile, the composite material is combined with abundant Mn-Co-C or Mn-C-Co bond groups in the ACF, so that the catalytic activity can be further improved. The above discussion shows that rich chemical bonds exist between Co-Mn and ACFs, which can act synergistically to improve Charge Transfer Efficiency (CTE), and generate free radicals and non-free radicals in the presence of PMS to improve catalytic performance. As can be seen, Co was produced in inventive example 1 3 O 4 -Mn 3 O 4 The @ ACFs catalytic material has the best degradation effect on CIP. In addition, the preparation method adopted by the invention has the advantages of simple process, easy operation, low cost, no pollution and the like, and the prepared catalyst or the preparation method has better application prospect in the field of advanced oxidation water treatment.
Example 5
Examining Co of the present invention 3 O 4 -Mn 3 O 4 The recycling and stability of the @ ACFs catalyst in the process of degrading CIP by activating PMS comprises the following steps:
(1) 0.05g of Co prepared in example 1 was weighed 3 O 4 -Mn 3 O 4 @ ACFs catalyst in an initial concentration of 10mg L to 100mL -1 And obtaining a reaction system in the ciprofloxacin wastewater.
(2) Placing the reaction system obtained in the step (1) on a magnetic stirrer, and taking the concentration of the original solution measured by an ultraviolet-visible spectrophotometer as C 0 Adding PMS and catalyst, stirring, adding 2mL of solution at certain time intervals into a centrifuge tube filled with 1mL of methanol, and measuring CIP residual concentration in supernatant with ultraviolet-visible spectrophotometer as C t
(3) And (3) clamping the composite material reacted in the step (2) by using tweezers to pick up the catalyst, shaking and cleaning the composite material by using ethanol and deionized water for a plurality of times (aiming at desorbing CIP by using ethanol), centrifuging, drying, weighing, and adding the composite material into 100mL ciprofloxacin wastewater with the initial concentration of 10mg/L again.
(4) And (4) continuously repeating the steps (2) to (3) for four times.
(5) FIG. 6 shows Co in example 3 of the present invention 3 O 4 -Mn 3 O 4 And (3) a corresponding cycle number-degradation efficiency graph when the @ ACFs catalyst is used for circularly degrading Ciprofloxacin (CIP) wastewater. In fig. 6, the degradation efficiency of CIP is plotted on the ordinate, wherein 1, 2, and 3 correspond to the catalytic degradation efficiency of the first reaction, the second reaction, and the third reaction, respectively. As can be seen from this figure, after three cycles, Co 3 O 4 -Mn 3 O 4 @ ACFs showed good degradability. CIP removal decreased slightly from 96.79% (first time) to 93.69% (second time) and 93.12% (third time). Despite the slight decrease in catalytic efficiency in the third cycle, CIP still achieved almost complete degradation within 120 minutes, indicating that the catalyst was stable in long-term operation.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples. All technical solutions that fall within the spirit and principle of the present invention are included in the scope of the present invention.

Claims (9)

1. The composite material is prepared by a simple seed-mediated coprecipitation method, and a three-step method is adopted in the composite process. First, HNO is used in the initial stage of the process 3 Solution (4mol L) -1 ) Soaking for 24 hours to pretreat the Activated Carbon Fiber (ACF). Then, Co 3 O 4 The particles are loaded and grown on the ACFs. Finally, Co 3 O 4 The particles were used as seeds by coprecipitation of Mn on ACFs supports 3 O 4 Forming a composite material.
According to the invention, firstly, the activated carbon fiber is pretreated, the mesoporous surface area of the activated carbon fiber is increased, Co is loaded on the carbon fiber by adopting a hydrothermal method, and then the Co is pyrolyzed at 300 ℃ in a nitrogen atmosphere to generate the cobaltosic oxide @ activated carbon fiber (Co3O4@ ACFs) composite catalyst. Finally, Mn is loaded on the composite material by the hydrothermal method, and the composite material is pyrolyzed and reinforced at 300 ℃ in a nitrogen atmosphere to obtain Co 3 O 4 -Mn 3 O 4 @ ACF nanocomposite catalyst. Acid soaking activated carbon fiberAfter pretreatment, the nano manganese cobalt oxide material has high specific surface area and strong adsorption capacity, simultaneously has rich chemical functional groups, shows strong activity, can enhance the stability and the dispersibility of the nano manganese cobalt oxide material, and can improve the contact area and the retention time of pollutants on the surface of the material. The metal nano material dispersed on the active carbon fiber can prevent agglomeration in the growth process, thereby improving the catalytic activity and the catalytic efficiency. The material is prepared at relatively low temperature, so that the material has more abundant chemical bonds, and the loss of metal ions can be reduced due to the strong covalent bond interaction of Mn-Co-C, Co-C-Mn between the manganese cobalt oxide and the activated carbon fiber. Meanwhile, Mn is caused in view of the difference in oxidation-reduction potential of the bimetal oxide 2+ Promotion of Co 3+ To Co 2+ The conversion process of (a) enhances the continuous decomposition of PMS and the generation of free radicals at the catalyst surface. The synergistic effect between the manganese cobalt oxide and the activated carbon fiber can obviously improve the persulfate activation capability of the composite material, and has the potential of practical large-scale application.
2. Co for activating PMS (PMS) catalytic degradation antibiotics according to claim 1 3 O 4 -Mn 3 O 4 The @ ACF nano composite catalyst is characterized in that: the formed metal nano particles are uniformly distributed on the surface of the carbon substrate and form covalent bonds with the carbon fibers, so that the stability of the catalyst is further improved.
3. Co for activating PMS catalytic degradation antibiotics according to claim 1 or 2 3 O 4 -Mn 3 O 4 The preparation method of the @ ACF catalyst comprises the following steps:
the pretreatment of the activated carbon fiber comprises the following steps:
s1, cutting the activated carbon fiber into small pieces of 2cm multiplied by 2cm, placing the small pieces in ultrapure ion removal water, and cleaning until no obvious floating black impurities exist;
s2, soaking the activated carbon fiber in 4mol/L nitric acid solution for 24 hours;
s3, washing the activated carbon fiber by oscillating with 4% hydrochloric acid in water bath at 50 ℃ for 40 min;
s4, collecting the material, washing with deionized water until the pH of the washing liquid is neutral, ultrasonically treating with deionized water for 30min, and drying at 80 ℃ for 12 h.
Co 3 O 4 The synthesis method of the @ ACFs seed precursor comprises the following steps:
s5, weighing a mixture of cobalt nitrate, ammonium fluoride and urea, dissolving in aqueous ethanol, and fully stirring to form a mixed solution;
s6, taking the activated carbon fiber as a carbon carrier, and soaking 1.0g of the activated carbon fiber in the mixed solution. The particles are uniformly distributed in the activated carbon fiber by ultrasonic treatment for 1h, and the material is transferred to a hydrothermal reactor. Keeping the temperature at 100 ℃ for 12h, and naturally cooling after reaction;
s7, washing the composite material with distilled water and absolute ethyl alcohol under ultrasonic waves for three to five times, and placing the composite material in an oven for vacuum drying;
s8, placing the hydrothermal product in a tubular calcining furnace, and heating at the speed of 5 ℃/min in N 2 Heating to 300 ℃ under protection and keeping for 3h to synthesize Co 3 O 4 @ ACFs precursor seed composites.
Co 3 O 4 -Mn 3 O 4 The synthesis method of the @ ACFs composite material comprises the following steps:
s9, weighing KMnO 4 Dissolving in absolute ethyl alcohol, and fully stirring for 4 hours;
s10, adding the composite material into a potassium permanganate solution, continuing stirring for 1h, and performing ultrasonic treatment for 1h to uniformly disperse the particles in Co 3 O 4 @ ACFs composite;
s11, placing the mixture in a hydrothermal reaction kettle, heating for 12 hours at 100 ℃ to enable the mixture to undergo oxidation-reduction reaction to grow manganese oxide, and naturally cooling the composite material after reaction;
and S12, respectively washing the composite material with distilled water and absolute ethyl alcohol for three to four times in the ultrasonic washing process, wherein each time is 10min, and then placing the composite material in a vacuum drying oven for drying.
S13, putting the obtained composite material in a tube furnace N 2 Treating at 300 deg.C for 90min under protection to obtainAnd (4) carrying out heat treatment on the compound to finally synthesize the composite material.
4. Co for activating PMS catalytic degradation antibiotics according to claim 3 3 O 4 -Mn 3 O 4 The preparation method of the @ ACFs composite catalyst is characterized in that in the steps S5 and S9: dissolving the cobalt nitrate (0.2mmol), the ammonium fluoride (0.1mmol) and the urea (0.2mmol) in 100mL of absolute ethanol; the stirring is carried out under the condition that the rotating speed is 600 r/min-1000 r/min; the stirring time is about 4 hours; the potassium permanganate is 0.1g, and is dissolved in 100mL of absolute ethyl alcohol.
5. The process for the preparation of the MOFs-derived CuCo/C catalyst for activating PMS catalytic degradation antibiotics according to claim 3, wherein in steps S3 and S4: the reaction temperature is 150 ℃, and the reaction time is 72 hours; the drying time is 12h, and the temperature is 70 ℃.
6. Co oxidative degradation of antibiotics with activated PMS according to claim 1 or 2 3 O 4 -Mn 3 O 4 Application of the @ ACFs composite material catalyst in antibiotic wastewater degradation.
7. The use of claim 6, wherein the antibiotic is ciprofloxacin.
8. The application according to claim 6, characterized in that it comprises the following steps: adding the prepared catalyst into wastewater containing antibiotics to obtain mixed liquor, and stirring for 2h without adding PMS to obtain the adsorption efficiency of the catalyst; then adding PMS to continue reacting for 2h to finish the degradation of antibiotics in the water body; the addition amount of the catalyst is that Co is added into each liter of antibiotic wastewater 3 O 4 -Mn 3 O 4 @ ACFs composite catalyst 0.05 g.
9. According to the rightThe use according to claim 8, wherein the concentration of the antibiotic in the wastewater is 10mg L -1 (ii) a The stirring treatment time under the condition without adding PMS is 2 h; the catalytic reaction time of the activated PMS is 2 hours; the stirring treatment is carried out at a rotating speed of 550-600 r/min.
CN202210805960.XA 2022-07-10 2022-07-10 Preparation and application of active carbon fiber loaded cobalt-manganese bimetallic oxide catalyst Pending CN115069265A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115888717A (en) * 2022-11-11 2023-04-04 武汉轻工大学 Charcoal-loaded nano CoOOH catalyst for efficiently activating persulfate and preparation method thereof
CN116212916A (en) * 2022-12-07 2023-06-06 新乡医学院 Cobalt-manganese-based composite catalyst, preparation method thereof and application thereof in degradation of antibiotics by activated peroxymonosulfate

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115888717A (en) * 2022-11-11 2023-04-04 武汉轻工大学 Charcoal-loaded nano CoOOH catalyst for efficiently activating persulfate and preparation method thereof
CN115888717B (en) * 2022-11-11 2023-10-17 武汉轻工大学 Charcoal loaded nano CoOOH catalyst for efficiently activating persulfate and preparation method thereof
CN116212916A (en) * 2022-12-07 2023-06-06 新乡医学院 Cobalt-manganese-based composite catalyst, preparation method thereof and application thereof in degradation of antibiotics by activated peroxymonosulfate

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