CN112295573B

CN112295573B - electro-Fenton catalyst and preparation method and application thereof

Info

Publication number: CN112295573B
Application number: CN202011330498.XA
Authority: CN
Inventors: 高娟; 楚龙港; 孙昭玥
Original assignee: Institute of Soil Science of CAS
Current assignee: Institute of Soil Science of CAS
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2021-12-10
Anticipated expiration: 2040-11-24
Also published as: CN112295573A

Abstract

Adding boric acid and graphene into water to form a mixed solution; transferring the mixed solution to a polytetrafluoroethylene reaction kettle for reaction, and centrifuging to obtain boron-doped graphene powder; adding boron-doped graphene and ferric nitrate nonahydrate into water, stirring to form a uniform solution, stirring the obtained solution in a water bath kettle, adding a hydrazine hydrate solution, transferring the obtained mixed solution into a polytetrafluoroethylene reaction kettle for reaction, and centrifuging the obtained mixed solution to obtain Fe coated with the boron-doped graphene₃O₄Powder; fe coated with boron doped graphene₃O₄Putting the mixed powder and sulfur powder into an alumina crucible, putting the crucible into a tubular furnace for high-temperature reaction, taking out after natural cooling, cleaning the obtained powder, and then putting the powder into a vacuum drying oven to obtain the FeS wrapped by the boron-doped graphene₂。

Description

electro-Fenton catalyst and preparation method and application thereof

Technical Field

The invention belongs to the field of environmental pollution treatment, and particularly relates to an electro-Fenton catalyst, and a preparation method and application thereof.

Background

With the rapid development of Chinese economy, industrial production wastewater has the characteristics of complex water quality, difficult biodegradation, high concentration and high toxicity, and the wastewater is difficult to reach the standard by the traditional biochemical method, so that serious water resource pollution is caused. The treatment of industrial wastewater has become a difficult point in the field of water pollution control.

Advanced oxidation technology developed in the 80 s of the 20 th century canThe high-activity intermediate hydroxyl radical (OH) generated by physical and chemical processes such as light, sound, electricity, magnetism and the like is utilized to quickly mineralize pollutants or improve the biodegradability of the pollutants, and the method has the characteristics of high reaction rate and strong oxidation capability. Fenton oxidation is most widely used in advanced oxidation technology, using Fe at pH 2-5²⁺Catalytic decomposition of H₂O₂The generated hydroxyl radicals degrade pollutants, but the traditional Fenton needs to add a large amount of activators, namely iron and hydrogen peroxide, and the cost is too high; and a higher dosage of chemical substances is required to acidify the wastewater to a pH of 2-5, causing environmental damage. The electro-Fenton technique utilizes cathode energy to continuously generate H by cathode reduction reaction₂O₂Meanwhile, the iron-containing solid catalyst is used as an iron source, the application range of the pH value is expanded to 3-9, and the method has the characteristics of less used raw materials and environmental friendliness.

In recent years, research focus of electro-fenton has been on the preparation of a solid catalyst having high catalytic performance and being capable of being reused. Such catalysts are often iron, copper, and other transition metal containing materials that activate the cathode-generated H₂O₂OH-degrading contaminants are produced. For example, the invention of China: CN201610173670.2 magnetic Fe₃O₄Particle coupling electro-Fenton reactor and treatment method for distributed sewage recycling by using the reactor. The invention relates to the field of sewage treatment, in particular to magnetic Fe₃O₄A particle coupling electro-Fenton reactor and a treatment method for recycling distributed sewage by using the reactor. Fe₃O₄The particles are made of waste iron filings through hydrothermal synthesis method, and the magnetic Fe₃O₄The dosage of the particles is 40-160mg/L, the voltage of the direct current stabilized voltage supply is 0.5-10V, the preset time is 30-120min, and the result shows that the magnetic Fe is added₃O₄The particles can obviously improve the removal rate of the reaction system to ammonia nitrogen, and can realize high-efficiency dephosphorization efficiency at the same time. But Fe₃O₄Has a low catalytic performance on H₂O₂The utilization rate of the catalyst is low, the dissolution rate is high, and other metal elements such as copper, cobalt, gold and the like are often doped in the catalyst for improving the catalytic performance of the catalyst.

For another example, the invention of China: CN201510781846.8 AuPd/Fe₃O₄An in-situ electro-Fenton catalyst, a preparation method and application thereof. Said invention utilizes the dimensionally stable electrode plates of titanium-ruthenium net, etc. as cathode and anode of electrochemical reactor respectively, and makes the prepared AuPd/Fe with a certain quantity₃O₄The catalyst is uniformly dispersed in the reaction solution, under the action of an external electric field, the cathode and the anode respectively generate hydrogen and oxygen, the adsorbed oxygen is reduced on the surface of the catalyst to generate hydrogen peroxide in situ, and simultaneously, ferrous ions are released in situ due to hydrogen reduction, so that Fenton reaction occurs, hydroxyl radicals with strong oxidizing property are generated to oxidize and degrade organic pollutants, and the water quality is purified. Said invention improves Fe₃O₄However, the Au/Pd noble metal has high price and is not suitable for the actual sewage treatment. Meanwhile, the catalyst still has the problem of dissolution and cannot be used for many times.

Aiming at the defects of the catalyst, the invention of China: CN201910690815.X preparation method and application of graphite carbon-coated iron-nitrogen-carbon solid-phase Fenton catalyst, a carbon source and a nitrogen source are mixed according to a certain proportion, heated and melted, an iron source is added according to a certain proportion, after the mixture is fully stirred and dissolved, the mixture is transferred to an oven at 150-180 ℃ for drying for 12-24 h, and then the mixture is calcined under the protection of nitrogen atmosphere to obtain the iron-nitrogen-carbon solid-phase Fenton catalyst; the catalyst contains Fe₃C and FeN nanoparticles; the outside of the particles is coated with graphite, and the catalyst prepared by the method is used as a solid-phase Fenton catalyst for catalyzing and decomposing H₂O₂The efficiency is high, the graphite carbon coating effectively prevents iron from dissolving out, the catalyst shows better stability and cyclability, and the pH application range is wide.

The excellent properties of graphene are much higher than those of graphite, and the catalytic performance of graphene doped with heteroatoms such as N, B can be improved, but at present, reports that an iron active component is wrapped by a doped graphene film to be used as a fenton catalyst exist, and the catalyst synthesis method needs to be further developed.

Disclosure of Invention

The technical problem to be solved is as follows: book (I)The invention provides an electro-Fenton catalyst, a preparation method and application thereof, and no exogenous oxidant is needed, and H is generated by using in-situ reduction oxygen of an electrode₂O₂The method has the advantages of low energy consumption, low cost, simple process and the like.

The technical scheme is as follows: boron doped graphene coated FeS₂The preparation method of the electro-Fenton catalyst comprises the following preparation steps: step 1, adding boric acid and graphene into water according to a mass ratio of 1:2 to form a mixed solution; transferring the mixed solution into a polytetrafluoroethylene reaction kettle to react for at least 12 hours at 180 ℃, and centrifuging to obtain boron-doped graphene powder; step 2, adding boron-doped graphene and ferric nitrate nonahydrate into water according to the mass ratio of 1:10, stirring to form a uniform solution, stirring the obtained solution in a water bath kettle at 70 ℃, simultaneously adding 60wt.% hydrazine hydrate solution, wherein the volume ratio of the hydrazine hydrate solution to the uniform solution is 6:1, transferring the obtained mixed solution into a polytetrafluoroethylene reaction kettle, reacting at 150 ℃ for at least 6 hours, and centrifuging the obtained mixed solution to obtain Fe coated with the boron-doped graphene₃O₄Powder; step 3, wrapping boron-doped graphene with Fe₃O₄Putting the powder and sulfur powder into an alumina crucible according to the mass ratio of 1:10, putting the crucible into a tubular furnace, reacting for 6 hours at the high temperature of 450 ℃, taking out after natural cooling, respectively cleaning the obtained powder with sulfuric acid and water, and then putting the powder into a vacuum drying oven at the temperature of 80 ℃ for at least 12 hours to obtain the FeS coated with the boron-doped graphene₂。

The preferred preparation method is as follows: step 1, adding 0.06g of boric acid and 0.12g of graphene into 60mL of water, and stirring for 30 minutes to form a mixed solution; transferring the solution into a polytetrafluoroethylene reaction kettle to react for at least 12 hours at 180 ℃, and centrifuging to obtain boron-doped graphene powder; step 2, adding 0.04g of boron-doped graphene and 0.40g of ferric nitrate nonahydrate into 60mL of water, stirring for 10 minutes to form a uniform solution, stirring the obtained solution in a water bath kettle at 70 ℃ for 7 hours, adding 5mL of 60wt.% hydrazine hydrate solution into the solution, and transferring the obtained mixed solution into a polytetrafluoroethylene reaction kettle to react at 150 ℃ for at least 6 hours; centrifuging the obtained mixed solution to obtain boron-doped graphene-coated Fe₃O₄Powder; step 3, wrapping 0.10g of boron-doped graphene with Fe₃O₄And 1.00g of sulfur powder are put in an alumina crucible, the crucible is put in a tube furnace for high-temperature reaction at 450 ℃ for 6 hours, the crucible is taken out after natural cooling, the obtained powder is respectively cleaned by sulfuric acid and water, and then the powder is put in a vacuum drying oven at 80 ℃ for at least 12 hours to obtain FeS wrapped by boron-doped graphene₂。

The preparation method is used for preparing the FeS wrapped by the boron-doped graphene₂An electro-Fenton catalyst.

The boron-doped graphene-coated FeS₂The application of the electro-Fenton catalyst in preparing organic wastewater purification products.

The application method comprises the steps of introducing the organic wastewater to be treated into an electrochemical reactor, taking graphite as an anode and a modified carbon felt as a cathode, aerating near the cathode, adding an electro-Fenton catalyst, then mechanically stirring, and keeping the reaction time at 0-20 minutes.

The voltage is kept between 0.5 and 2V, the current is kept between 50 and 100mA, the modified carbon felt is a carbon felt modified according to the mass ratio of PTFE to carbon black of 7 to 3, and the pH value of the wastewater is between 7.2 and 7.6.

Has the advantages that: according to the invention, boron atoms are doped into a planar structure of graphene by adding boric acid to obtain boron-doped graphene, and FeS wrapped by the boron-doped graphene is prepared by hydrothermal and high-temperature calcination₂A catalyst. Wherein both boron and iron can be used as active sites to activate H₂O₂OH is generated to oxidize and degrade pollutants. The invention utilizes boron and iron as catalytic H₂O₂At a higher pH range (3-9) to achieve high concentrations of contaminants (50 mg. L)^-1) The degradation is rapid, and the degradation rate of the pollutants in 20min is 100%. In the invention, FeS is coated by the boron-doped graphene oxide film₂Less dissolution and still no reduction of catalytic efficiency under multiple cycles.

Drawings

FIG. 1 shows FeS synthesized in example 1₂Scanning electron microscopy images of @ BrGO;

FIG. 2 is a schematic view of an embodimentExample 1 synthetic FeS₂Transmission electron microscopy images of @ BrGO;

FIG. 3 shows FeS synthesized in example 1₂XRD pattern of @ BrGO;

FIG. 4 is a graph comparing the degradation of bisphenol A by several catalysts under the same electro-Fenton conditions;

FIG. 5 shows FeS at different pH conditions₂A graph of the concentration change of bisphenol A degraded by the @ BrGO electro-Fenton system;

FIG. 6 shows FeS at pH 7.4₂And the degradation rate of the @ BrGO electro-Fenton system to different pollutants is shown.

Detailed Description

Example 1

Synthesis of FeS₂@ BGO in-situ electro-Fenton catalyst and efficiency comparison of treatment of bisphenol A polluted wastewater by different catalysts in electro-Fenton system

Step 1, preparation of boron-doped graphene substrate (BGO): adding 0.06g of boric acid and 0.12g of graphene into 60mL of water, and stirring for 30 minutes to form a mixed solution; transferring the solution into a polytetrafluoroethylene reaction kettle to react for at least 12 hours at 180 ℃; centrifuging the obtained solution in a high-speed centrifuge for 5 minutes at 8000 revolutions, wherein the obtained powder is boron-doped graphene;

step 2, wrapping Fe by boron-doped graphene₃O₄Preparation of precursor (Fe)₃O₄@ BGO) 0.04g of boron-doped graphene and 0.40g of iron nitrate nonahydrate were added to 65mL of water, stirred for 10 minutes to form a uniform solution, the obtained solution was stirred in a water bath at 70 ℃ for 7 hours, 5mL of hydrazine hydrate solution was added to the above solution, and the obtained mixed solution was transferred to a polytetrafluoroethylene reaction kettle and reacted at 150 ℃ for at least 6 hours. Centrifuging the obtained mixed solution in a high-speed centrifuge at 8000 rpm for 5 min to obtain powder of Fe coated with boron-doped graphene₃O₄；

Step 3, wrapping FeS with boron-doped graphene₂(FeS₂@ BGO) 0.10g boron doped graphene coated Fe₃O₄And 1.00g of sulfur powder were put in an alumina crucible, the crucible was placed in a tube furnace at 450 ℃ for 6 hours, and after cooling naturally, the powder was taken out, washed and thenThen putting the mixture into a vacuum drying oven with the temperature of 80 ℃ for at least 12 hours to obtain the FeS wrapped by the boron-doped graphene₂。

FIGS. 1 and 2 show synthetic FeS₂In the scanning electron microscope and transmission electron microscope images of @ BGO, FeS can be seen₂The average diameter of the particles is between 5 and 50nm, and the outside of the particles is wrapped by a layer of boron-doped graphene film. FIG. 3 is a diagram of synthetic FeS₂The XRD pattern of @ BGO shows the characteristic peak shift from GO (001) to BGO (002), confirming BGO synthesis. BGO-wrapped FeS₂Then characteristic peaks of FeS2 appear at 28.4 degrees, 33.1 degrees, 37.2 degrees, 40.9 degrees and 47.4 degrees, which respectively correspond to FeS₂The (011), (200), (210), (211) and (220) crystal planes of the compound prove that the synthesized substance contains FeS with higher purity₂。

The efficiency comparison of bisphenol A polluted wastewater treatment in an electro-Fenton system by different catalysts is as follows: 500mL of bisphenol A-contaminated wastewater to be treated (concentration 50 mg. L)^-1) Introducing into an electrochemical reactor, taking graphite as an anode and modified carbon felt as a cathode, aerating near the cathode, and adding the same amount of Fe₃O₄，FeS₂，BGO，FeS₂The @ BGO powder is then mechanically stirred and the reaction time is maintained between 0 and 20 minutes. The voltage was held at 2V and the current was held at 50 mA. The modified carbon felt is modified by PTFE and carbon black in a mass ratio of 7: 3. The pH of the wastewater was 7.4.

FIG. 4 is a graph comparing the degradation effect of several catalysts on bisphenol A under the same conditions, and Fe can be observed in the same system₃O₄， FeS₂，BGO，FeS₂The degradation rate of @ BGO to bisphenol A polluted wastewater is as follows in sequence: 35%, 38%, 50%, 100%. FeS₂Compared with the other three catalysts, the catalyst performance of the @ BGO catalyst is greatly improved.

Example 2

FeS at different pH₂Concentration change diagram of @ BrGO electro-Fenton system degrading bisphenol A

500mL of bisphenol A-contaminated wastewater to be treated (concentration 50 mg. L)^-1) Adjusting pH to 3, 5, 7, 9 with sulfuric acid or sodium hydroxide, introducing into electrochemical reactor,taking graphite as an anode and modified carbon felt as a cathode, aerating near the cathode, and adding a certain amount of FeS₂The @ BGO powder is then mechanically stirred and the reaction time is maintained between 0 and 20 minutes. The voltage was held at 2V and the current was held at 50 mA. The modified carbon felt is modified by PTFE and carbon black in a mass ratio of 7: 3.

FIG. 5 shows FeS at different pH₂The comparative graph of the @ BGO electro-Fenton system on the degradation effect of the bisphenol A shows that the degradation rate of the bisphenol A can reach 100% in 20min under different pH conditions.

Example 3

FeS at pH 7.4₂Degradation rate of @ BrGO electro-Fenton system to different pollutants

500mL of wastewater (with the concentration of 50 mg. L) polluted by nitrobenzene, 2-chlorophenol, diethyl phthalate, sulfanilamide, tetracycline and dichlorophen 6 to be treated^-1) Introducing into an electrochemical reactor, taking graphite as an anode and modified carbon felt as a cathode, aerating near the cathode, and adding a certain amount of FeS₂The @ BGO powder is then mechanically stirred and the reaction time is maintained between 0 and 20 minutes. The voltage was held at 2V and the current was held at 50 mA. The modified carbon felt is modified by PTFE and carbon black in a mass ratio of 7: 3. The pH of the wastewater was 7.4.

FIG. 6 shows FeS at pH 7.4₂The degradation rate of the @ BrGO electro-Fenton system to different pollutants is shown, and FeS can be observed₂The @ BGO catalyst has good degradation capability on six kinds of waste water with different pollutions, and the degradation rate is between 83 and 100 percent.

Example 4

Degradation effect of different recycling times on pollutants

500mL of bisphenol A-contaminated wastewater to be treated (concentration 50 mg. L)^-1) Introducing into an electrochemical reactor, taking graphite as an anode and modified carbon felt as a cathode, aerating near the cathode, and adding a certain amount of FeS₂The @ BGO powder is then mechanically stirred and the reaction time is maintained between 0 and 20 minutes. After each reaction, the FeS after the reaction is collected by filtration₂@ BGO powder, drying in vacuum drying oven at 80 deg.C for 8 hr, taking out, and repeatingAnd (6) testing. The voltage was held at 2V and the current was held at 50 mA. The modified carbon felt is modified by PTFE and carbon black in a mass ratio of 7: 3.

TABLE 1

Number of reaction times	Rate of degradation	TOC removal Rate
			1	100％	50.1％
2	100％	49.8％
			3	100％	50.0％
4	100％	49.8％

As can be seen from Table 1, the degradation effect and TOC removal rate can still reach 100% and 50% after 4 times of repeated use, which indicates that FeS₂The @ BrGO catalyst has good recycling performance, and can be continuously utilized, so that the treatment cost can be greatly reduced.

The embodiments of the present invention are not limited to the above-described embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.

Claims

1. Boron doped graphene coated FeS₂The preparation method of the electro-Fenton catalyst is characterized by comprising the following preparation steps: step 1, adding boric acid and graphene into water according to a mass ratio of 1:2 to form a mixed solution; transferring the mixed solution into a polytetrafluoroethylene reaction kettle to react for at least 12 hours at 180 ℃, and centrifuging to obtain boron-doped graphene powder; step 2, adding boron-doped graphene and ferric nitrate nonahydrate into water according to the mass ratio of 1:10, stirring to form a uniform solution, stirring the obtained solution in a water bath kettle at 70 ℃, simultaneously adding 60wt.% hydrazine hydrate solution, wherein the volume ratio of the hydrazine hydrate solution to the uniform solution is 6:1, transferring the obtained mixed solution into a polytetrafluoroethylene reaction kettle, reacting at 150 ℃ for at least 6 hours, and centrifuging the obtained mixed solution to obtain Fe coated with the boron-doped graphene₃O₄Powder; step 3, wrapping boron-doped graphene with Fe₃O₄Putting the powder and sulfur powder into an alumina crucible according to the mass ratio of 1:10, putting the crucible into a tubular furnace, reacting for 6 hours at the high temperature of 450 ℃, taking out after natural cooling, respectively cleaning the obtained powder with sulfuric acid and water, and then putting the powder into a vacuum drying oven at the temperature of 80 ℃ for at least 12 hours to obtain the FeS coated with the boron-doped graphene₂。

2. Boron doped graphene coated FeS₂The preparation method of the electro-Fenton catalyst is characterized by comprising the following steps: step 1, adding 0.06g of boric acid and 0.12g of graphene into 60mL of water, and stirring for 30 minutes to form a mixed solution; transferring the solution into a polytetrafluoroethylene reaction kettle to react for at least 12 hours at 180 ℃, and centrifuging to obtain boron-doped graphene powder; step 2, adding 0.04g of boron-doped graphene and 0.40g of ferric nitrate nonahydrate into 60mL of water, stirring for 10 minutes to form a uniform solution, stirring the obtained solution in a water bath at 70 ℃ for 7 hours, and adding 5mL of 60wt.% hydrazine hydrate into the solutionTransferring the obtained mixed solution into a polytetrafluoroethylene reaction kettle to react for at least 6 hours at 150 ℃; centrifuging the obtained mixed solution to obtain boron-doped graphene-coated Fe₃O₄Powder; step 3, wrapping 0.10g of boron-doped graphene with Fe₃O₄And 1.00g of sulfur powder are put in an alumina crucible, the crucible is put in a tube furnace for high-temperature reaction at 450 ℃ for 6 hours, the crucible is taken out after natural cooling, the obtained powder is respectively cleaned by sulfuric acid and water, and then the powder is put in a vacuum drying oven at 80 ℃ for at least 12 hours to obtain FeS wrapped by boron-doped graphene₂。

3. Preparation method of FeS wrapped by boron-doped graphene according to any one of claims 1-2₂An electro-Fenton catalyst.

4. The boron-doped graphene-encapsulated FeS of claim 3₂The application of the electro-Fenton catalyst in preparing organic wastewater purification products.

5. The use according to claim 4, characterized in that the organic waste water to be treated is introduced into an electrochemical reactor with graphite as anode, modified carbon felt as cathode and aeration near the cathode, mechanical stirring after adding electro-Fenton catalyst, the reaction time being maintained between 0 and 20 minutes.

6. The use of claim 5, wherein the voltage is maintained at 0.5-2V, the current is maintained at 50-100mA, the modified carbon felt is a carbon felt modified by PTFE to carbon black at a mass ratio of 7: 3, and the pH of the wastewater is 7.2-7.6.