CN110124683A - Mesoporous NiMn2O4The preparation method of catalyst, the catalyst thus prepared and application thereof - Google Patents

Abstract

The invention discloses a preparation method of a NiMn ₂ O ₄ nanometer catalyst with a mesoporous structure, the catalyst prepared therefrom and its application. The preparation method comprises steps: (1) adding P123, sodium lauryl sulfate, and hydrochloric acid solution to distilled water, then adding tetraethyl silicate, and performing hydrothermal treatment to obtain template KIT-6; (2) adding nickel nitrate and manganese nitrate Adding absolute ethanol to obtain a mixed solution A; (3) adding the template KIT‑6 to the solution A to form a mixed solution B; (4) evaporating the mixed solution B to dryness of the solvent under stirring in a water bath to obtain a solid C; (5) The black solid D was obtained by calcining the solid C; (6) The black solid D was washed with NaOH solution, then centrifugally filtered and dried to obtain a mesoporous NiMn ₂ O ₄ catalyst. According to the preparation method of the invention, the process is simple, the cost is low, and it is suitable for large-scale industrial production. The prepared mesoporous NiMn ₂ O ₄ nano-catalyst has good catalytic performance and can significantly improve the degradation of ciprofloxacin.

Description

Preparation method of mesoporous NiMn2O4 catalyst, catalyst prepared therefrom and use thereof

technical field

The invention belongs to the field of environmental electrochemical materials, the technical field of preparation and advanced oxidation technology for treating wastewater, and specifically relates to a method for preparing a NiMn ₂ O ₄ nanometer catalyst with a mesoporous structure, and the NiMn ₂ O ₄ nanometer catalyst obtained by the preparation method. Catalyst and its application in the degradation of antibiotic wastewater by Electro-Fenton Advanced Oxidation Technology.

Background technique

With the rapid development of the pharmaceutical industry, drugs have become a new class of environmental pollutants, posing a huge threat to the water environment and human health. Among them, antibiotic pollution and the harm caused by it have aroused widespread concern at home and abroad. Ciprofloxacin is a typical pollution source among antibiotics. The wastewater has strong antibacterial ability and is biodegradable. If it is directly discharged into the environment without purification treatment, it will cause toxic and side effects and induce bacteria to develop drug resistance. and cause harm to other biological gene mutations, and also pose a potential threat balance to the water environment and ecology. Therefore, it is imminent to realize efficient degradation of residual ciprofloxacin in the environment.

Advanced oxidation technology has great potential in degrading ciprofloxacin wastewater. Electro-Fenton advanced oxidation technology, as a representative advanced oxidation technology, has the advantages of mild conditions, strong oxidation ability, and fast reaction speed. It has shown excellent results in degrading ciprofloxacin wastewater and has been widely focus on. The electro-Fenton reaction mechanism generally consists of H ₂ O ₂ and Fe ²⁺ produced by electrochemical reactions as a continuous source of Fenton reagents to generate hydroxyl radicals OH, which trigger a series of chain reaction to degrade organic pollutants.

The yield of hydrogen peroxide is the key factor for the degradation of ciprofloxacin by the electro-Fenton system. In order to increase the production of hydrogen peroxide, usually low-cost carbon felt is used as the cathode material, and the cathode material is modified with Fenton catalyst, so as to increase more oxygen vacancies, thereby greatly increasing the amount of oxygen adsorption and generating more H ₂ O ₂ . However, the Fenton catalysts that are currently being studied have the problems of low concentration of hydrogen peroxide, slow degradation rate, and secondary pollution such as iron sludge. Therefore, there is still a need to develop more efficient cathode catalyst materials.

Contents of the invention

The invention provides a preparation method of an environment-friendly catalyst capable of increasing hydrogen peroxide output, greatly increasing degradation rate, and the catalyst can be used as a catalyst material for modifying carbon felt cathodes. The catalyst is a mesoporous NiMn ₂ O ₄ nanocatalyst with a higher specific surface area. The larger specific surface area can provide more active sites for hydrogen peroxide generation, and metal species (manganese and nickel) can promote the activation process. Hydrogen oxidation produces hydroxyl radicals, which further increase the efficiency of degrading the antibiotic ciprofloxacin.

An object of the present invention is to provide a kind of mesoporous NiMn ₂ O _The preparation method of nano-catalyst, described preparation method comprises the following steps:

(1) Add P123, sodium lauryl sulfate, and hydrochloric acid solution into distilled water, stir until completely dissolved, add tetraethyl silicate after dissolving, continue stirring, transfer the solution to a polytetrafluoroethylene reactor, Heating at 120°C for 20-25h, then cooling the solution to room temperature and washing with centrifugal filtration, drying the obtained solid for 8-10h to obtain a white powder, which is the template KIT-6;

(2) Nickel nitrate hexahydrate and manganese nitrate tetrahydrate are added in absolute ethanol, stirred until fully dissolved, forming mixed solution A;

(3) Add the template KIT-6 obtained in step 1) into solution A, and stir vigorously for 20-25 hours to form mixed solution B;

(4) Evaporate the mixed solution B to dry ethanol solvent under the condition of stirring in a water bath at 50-60° C. to obtain solid C;

(5) Calcining solid C in a muffle furnace at 350-400°C for 4-5 hours to obtain black solid D;

(6) Wash the black solid D with NaOH solution three times, and then wash it through centrifugal filtration until it becomes neutral, and dry the solid obtained by centrifugation at 40-50°C to obtain a black solid, which is mesoporous NiMn ₂ O ₄ catalyst.

Preferably, in step ( ¹ ), 38.5 parts by weight of P123, 4.4 parts by weight of sodium lauryl sulfate, 461.5 parts by weight of hydrochloric acid solution and 82.7 parts by weight of silicic acid are added per 1000 parts by weight of distilled water tetraethyl ester.

Preferably, in step (2), the added amount of nickel nitrate hexahydrate and manganese nitrate tetrahydrate is 70 parts by weight per 1000 parts by weight of absolute ethanol, and the molar ratio of nickel and manganese is 1:2.

Preferably, in step (3), based on 100 parts by weight of the sum of manganese nitrate tetrahydrate and nickel nitrate hexahydrate, the amount of template KIT-6 prepared in step (1) is added in an amount of 30-50 parts by weight. The template KIT6 has an ordered mesoporous structure and a unique pore structure, which is conducive to the loading of active species and is evenly loaded in the pore. The total amount of loaded salts should be sufficient to be fully impregnated and filled into the pores.

Preferably, in step (5), the heating rate of the muffle furnace is set to 1°C·min ^-1 .

Another object of the present invention is to provide a mesoporous NiMn ₂ O ₄ nano-catalyst prepared by the above method, which has a relatively high specific surface area and good catalytic degradation activity.

Another object of the present invention is to provide the application of the carbon felt modified by the above-mentioned mesoporous NiMn ₂ O ₄ nanocatalyst as a cathode material in degrading the antibiotic ciprofloxacin.

Another object of the present invention is to provide a method for degrading the antibiotic ciprofloxacin, the method adopts an electric Fenton system, wherein the carbon felt as the cathode material is made of mesoporous NiMn ₂ O ₄ nanometers prepared according to the preparation method of the present invention catalyst modification.

Beneficial effect

According to the preparation method of the invention, the process is simple, the cost is low, and it is suitable for large-scale industrial production. The prepared mesoporous NiMn ₂ O ₄ nano-catalyst has good catalytic performance and can significantly improve the degradation of ciprofloxacin.

Description of drawings

Fig. 1 is the degradation rate curve of the antibiotic ciprofloxacin by the mesoporous NiMn _{2 O 4 prepared in Example 1 and the non-mesoporous NiMn 2 O 4 catalyst prepared} in Comparative Example 1.

Fig. 2 is the TOC removal rate curves of the mesoporous NiMn _{2 O 4 prepared in Example 1 and the non-mesoporous NiMn 2 O 4 catalyst prepared} in Comparative Example 1.

FIG. 3 is the XPS spectrum of the mesoporous NiMn ₂ O ₄ prepared in Example 1.

Detailed ways

Hereinafter, the present invention will be described in detail. Before proceeding with the description, it should be understood that the terms used in this specification and appended claims should not be construed as limited to ordinary and dictionary meanings, but should be best interpreted while allowing the inventor to properly define the terms On the basis of the principles of the present invention, explanations are made based on meanings and concepts corresponding to the technical aspects of the present invention. Accordingly, the descriptions set forth herein are preferred examples for illustrative purposes only and are not intended to limit the scope of the invention, so that it should be understood that other, etc. price or improvement.

The following examples are only listed as examples of embodiments of the present invention, and do not constitute any limitation to the present invention. Those skilled in the art can understand that modifications within the scope of not departing from the essence and design of the present invention all fall into the protection of the present invention. scope. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

Example

Example 1

(1) Add P123, sodium lauryl sulfate, and hydrochloric acid solution into distilled water, stir at 30°C until completely dissolved, add tetraethyl silicate after dissolution, keep stirring at 30°C for 24 hours, and transfer the solution to polytetrafluoroethylene Reactor, heated at 100 ° C for 24h. Then the solution was cooled to room temperature, washed by centrifugal filtration, and the obtained solid was dried at 40°C for 12 hours to obtain a white powder, which was template KIT-6; in this step, 38.5 g of P123, 4.4 g of sodium lauryl sulfate, 461.5g of hydrochloric acid solution (2mol L ^-1 ) and 82.7g of tetraethyl silicate;

(2) Nickel nitrate hexahydrate and manganese nitrate tetrahydrate are added in dehydrated alcohol, stir until dissolving completely, form mixed solution A; The amount added is 70g in total, and the molar ratio of nickel and manganese is 1:2;

(3) Add the template KIT-6 obtained in step 1) into solution A, stir vigorously for 24 hours to form a mixed solution B; in this step, the added weight of template KIT-6 is the total amount of manganese nitrate tetrahydrate and nickel nitrate hexahydrate. 40% of the sum of the weights;

(4) The mixed solution B was evaporated to dry ethanol solvent under the condition of stirring in a water bath at 60° C. to obtain solid A;

(5) Calcining solid A in a muffle furnace at 350°C for 5h to obtain a black solid B; in this step, the heating rate of the muffle furnace was set to 1°C·min ⁻¹ ;

(6) Wash the black solid B with NaOH solution (2mol·L ^-1 ) three times, then wash it by centrifugal filtration until it becomes neutral, and dry the solid obtained by centrifugation at 40°C to obtain a black solid, which is medium Porous NiMn ₂ O ₄ catalyst.

The specific surface area of the mesoporous NiMn ₂ O ₄ catalyst prepared in this example was determined to be 262m ² ·g ^-1 by the BET method. In addition, it was proved by XPS that the Ni in it mainly exhibits +2 and +3 valences, and the Mn mainly Shown as +3 valence and +4 valence. FIG. 3 is the XPS spectrum of the mesoporous NiMn ₂ O ₄ prepared in Example 1.

Comparative Example 1

For comparison, a non-mesoporous NiMn ₂ O ₄ catalyst was prepared, and its preparation method was similar to that in Example 1, except that no KIT-6 template was added during the preparation process.

The specific process of the synthesis of non-mesoporous NiMn ₂ O ₄ catalyst is as follows:

(1) Add nickel nitrate hexahydrate and manganese nitrate tetrahydrate into absolute ethanol, stir vigorously for 24 hours to form mixed solution C;

In this step, the addition of nickel nitrate hexahydrate and manganese nitrate tetrahydrate in every 1.0L dehydrated alcohol is 70g altogether, and the mol ratio of nickel and manganese is 1:2;

(2) Evaporate the mixed solution C to dryness of absolute ethanol solvent under the condition of stirring in a water bath at 60° C. to obtain solid C;

(3) The solid C was calcined in a muffle furnace at 350° C. for 5 h to obtain a black solid B, which was a non-mesoporous NiMn ₂ O ₄ catalyst.

Table 1 lists the property data of the mesoporous NiMn ₂ O ₄ catalyst and the non-mesoporous NiMn ₂ O ₄ catalyst prepared in Example 1 and Comparative Example 1.

Table 1

Test Example 1: Test on the Degradation of Ciprofloxacin

(1) Take 100 mL of the prepared ciprofloxacin simulation solution in a cylindrical glass cell, use a Pt sheet (1.0 cm × 2.0 cm) as the anode and a catalyst-modified carbon felt (2.0 cm × 3.0 cm) as the cathode, And the distance between the two electrodes is 1.0 cm. From 30 min before the start of electrolysis to the end of the experiment, oxygen (O ₂ ) was injected into the solution at a flow rate of 50 ml·min ^-1 .

In this step, the concentrations of ciprofloxacin, Fe ²⁺ and electrolyte Na ₂ SO ₄ in the ciprofloxacin simulated solution are 0.1mmol·L ^-1 , 0.1mmol·L ^-1 and 0.05mol·L ^-1 respectively , and its initial pH value was adjusted to 3.0 by 0.1mol·L ^-1 H ₂ SO ₄ .

(2) At 0min, 10min, 20min, 30min, 40min, 50min, 60min, 75min, 90min, 105min, and 120min of electrolysis, take a certain amount of degradation solution to pass through the membrane, and measure it at λ=278nm by an ultraviolet-visible spectrophotometer The concentration C of ciprofloxacin in the corresponding solution.

(3) The degradation efficiency calculation formula of ciprofloxacin is as follows:

Degradation efficiency (%) = (C ₀ -C)/C ₀ ×100% (1)

C ₀ : initial concentration of ciprofloxacin;

C: The concentration of ciprofloxacin in the reaction solution under different degradation times.

Fig. 1 is the degradation rate curve of the antibiotic ciprofloxacin by the mesoporous NiMn _{2 O 4 prepared in Example 1 and the non-mesoporous NiMn 2 O 4 catalyst prepared} in Comparative Example 1.

Test Example 2: Test on TOC removal

(1) Take 100 mL of the prepared ciprofloxacin simulation solution in a cylindrical glass cell, use a Pt sheet (1.0 cm × 2.0 cm) as the anode and a catalyst-modified carbon felt (2.0 cm × 3.0 cm) as the cathode, And the distance between the two electrodes is 1.0 cm. From 30 min before the start of electrolysis to the end of the experiment, oxygen (O ₂ ) was injected into the solution at a flow rate of 50 ml·min ^-1 .

In this step, the concentrations of ciprofloxacin, Fe ²⁺ and electrolyte Na ₂ SO ₄ in the ciprofloxacin simulated solution are 0.1mmol·L ^-1 , 0.1mmol·L ^-1 and 0.05mol·L ^-1 respectively , and its initial pH value was adjusted to 3.0 by 0.1mol·L ^-1 H ₂ SO ₄ .

(2) At 0 min, 30 min, 60 min, 120 min, 180 min, 240 min, and 300 min of electrolysis, take a certain amount of degradation solution to pass through the membrane, and measure the value c of TOC in the corresponding solution by a total organic carbon analyzer.

(3) The calculation formula of TOC removal efficiency is as follows:

TOC removal efficiency (%)=(c ₀ -c)/c ₀ ×100%……………(2)

c ₀ : initial TOC;

c: TOC in the reaction solution under different degradation times.

Fig. 2 is the TOC removal rate curves of the mesoporous NiMn _{2 O 4 prepared in Example 1 and the non-mesoporous NiMn 2 O 4 catalyst prepared} in Comparative Example 1.

Claims (8)

1. a kind of mesoporous NiMn₂O₄The preparation method of nanocatalyst, the preparation method comprises the following steps:

(1) distilled water is added in P123, lauryl sodium sulfate, hydrochloric acid solution, stirs to being completely dissolved, silicic acid is added after dissolution Tetra-ethyl ester continues to stir, solution is transferred in ptfe autoclave, and 20-25h is heated at 80-120 DEG C, then will Solution is cooled to room temperature rear centrifugal filtration washing, by the dry 8-10h of solid obtained, obtains white powder, as template KIT-6；

(2) six water nickel nitrates and four water manganese nitrates are added to absolute ethanol, stirring forms mixed solution A to being completely dissolved；

(3) template KIT-6 obtained in step 1) is added in solution A, is vigorously stirred 20-25h, form mixed solution B；

(4) mixed solution B is evaporated anhydrous ethanol solvent under the conditions of 50-60 DEG C of stirring in water bath, obtains solid C；

(5) solid C is calcined into 4-5h in 350-400 DEG C of Muffle furnace, obtains black solid D；

(6) black solid D is washed three times with NaOH solution, washs using centrifugal filtration to being in neutrality, will be finally centrifuged To solid dried at 40-50 DEG C, obtain black solid, as mesoporous NiMn₂O₄Catalyst.

2. preparation method according to claim 1, which is characterized in that in step (1), add in every 1000 parts by weight distilled water Entering 38.5 parts by weight P123,4.4 parts by weight lauryl sodium sulfate, 461.5 parts by weight concentration is 2molL^-1Hydrochloric acid solution With 82.7 parts by weight tetraethyl orthosilicates.

3. preparation method according to claim 1, which is characterized in that in step (2), in every 1000 parts by weight dehydrated alcohol The additive amount of six water nickel nitrates and four water manganese nitrates is 70 parts by weight altogether, and the molar ratio of nickel and manganese is 1:2.

4. preparation method according to claim 1, which is characterized in that in step (3), be based on 100 parts by weight, four water nitric acid The summation of manganese and six water nickel nitrates, the additive amount 30-50 parts by weight of the middle template KIT-6 prepared of step (1)；The template KIT6 With ordered mesopore structure and distinctive cellular structure, be conducive to the load of active specy, and the Load Balanced in duct, bear The total amount for carrying salt, which will meet, can be sufficiently impregnated and be filled into duct.

5. preparation method according to claim 1, which is characterized in that in step (5), the heating rate of Muffle furnace is set as 1℃·min^-1。

6. a kind of mesoporous NiMn that preparation method as claimed in any of claims 1 to 5 is prepared₂O₄Nanometer is urged Agent.

7. mesoporous NiMn according to claim 6₂O₄Nanocatalyst as modification carbon felt cathode material degradation antibiosis The application of plain Ciprofloxacin.

8. a kind of method for antibiotic ciprofloxacin of degrading, which is characterized in that this method is using electric Fenton-like system, wherein as yin The mesoporous NiMn that the carbon felt of pole material is prepared with preparation method as claimed in any of claims 1 to 5₂O₄It receives Rice catalyst modification.