CN112517042A

CN112517042A - Nitrogen-doped Fenton-like catalyst and preparation method and application thereof

Info

Publication number: CN112517042A
Application number: CN202011492223.6A
Authority: CN
Inventors: 胡春; 廖威翔; 吕来
Original assignee: Guangzhou University
Current assignee: Guangzhou University
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2021-03-19
Anticipated expiration: 2040-12-15
Also published as: CN112517042B

Abstract

The invention discloses a nitrogen-doped Fenton-like catalyst and a preparation method and application thereof, and relates to the technical field of water treatment. The preparation method of the nitrogen-doped Fenton-like catalyst disclosed by the invention comprises the following steps of: firstly, cyclodextrin reacts with a copper source to obtain a solid product after the reaction, then urea is added into the solid product suspension to react, and after the reaction is finished, the reaction product is dried and roasted to obtain the nitrogen-doped Fenton-like catalyst. The nitrogen-doped Fenton-like catalyst has a good degradation effect on organic pollutants in water, is good in stability, can be repeatedly used, has low consumption of hydrogen peroxide, and is suitable for wide application.

Description

Nitrogen-doped Fenton-like catalyst and preparation method and application thereof

Technical Field

The invention relates to the technical field of water treatment, in particular to a nitrogen-doped Fenton-like catalyst and a preparation method and application thereof.

Background

Fresh water resources are critical to the survival of all living beings, including human species. However, with the rapid development of industry, water pollution caused by dyes, pesticides and other organic pollutants is becoming serious, and the environment and human health are threatened greatly. Therefore, effective removal of organic contaminants is urgently required.

Fortunately, many effective treatment methods have been developed to remove organic contaminants from wastewater, such as physical adsorption, biodegradation, and membrane separation. Among these treatments, the Advanced Oxidation Process (AOPS) is considered as a powerful technique for treating wastewater pollution by decomposing organic dyes by hydroxyl radicals (· OH). The Fenton process is widely applied to industrial wastewater treatment as an advanced oxidation process. However, the classical Fenton process, both homogeneous and heterogeneous, involving contaminant degradation, is inefficient and less active under neutral conditions, and H₂O₂Are mainly due to the limitation of electron transfer speed and H₂O₂Is caused by the ineffective decomposition of (c). Therefore, the exploration and development of a high-efficiency Fenton-type catalyst under the neutral pH condition has attracted extensive attention at the present stage.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the novel high-efficiency energy-saving gas-liquid separator which has wide application range, does not generate secondary pollution and H in the using process₂O₂A nitrogen-doped Fenton-like catalyst with low ineffective decomposition rate, a preparation method and application thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a preparation method of a nitrogen-doped Fenton-like catalyst comprises the following steps:

(1) dispersing cyclodextrin and a copper source into a solvent, and stirring to obtain a suspension A;

(2) after the step (1) is finished, adding urea into the suspension A, stirring and evaporating to dryness to obtain a solid product A;

(3) after the step (2) is finished, drying the solid product A, and uniformly grinding to obtain a solid product B;

(4) and (4) after the step (3) is finished, roasting, cooling, washing and drying the solid product B to obtain the nitrogen-doped Fenton-like catalyst.

Preferably, in the step (1), the copper source is at least one of copper chloride, copper nitrate, copper acetate and copper sulfate, and the molar ratio of copper ions in the copper source to cyclodextrin is (0.2-5): 1, the solvent is methanol or ethanol.

Preferably, in the step (1), the molar ratio of the copper ions in the copper source to the cyclodextrin is 2: 1. The applicant of the invention verifies through multiple experiments that the nitrogen-doped Fenton-like catalyst prepared according to the proportion has the best degradation effect in the process of treating organic pollutants in water.

Preferably, the amount of urea added is 1-15g relative to 50-100mL of solvent.

Preferably, the amount of urea added is 8g per 60mL of solvent.

Preferably, in the step (2), the evaporating temperature is 60-90 ℃.

Preferably, in the step (3), the drying temperature is 50-80 ℃, and the drying time is 8-24 h.

Preferably, in the step (3), the drying temperature is 60 ℃ and the drying time is 12 h.

Preferably, in the step (4), the solid product B is roasted under inert gas or nitrogen, and the roasting is divided into two stages, namely a first stage: the roasting temperature is 300-: the roasting temperature is 600-1000 ℃, the roasting time is 1-5h, and the roasting temperature rise rate is 5 ℃.

Preferably, in the step (4), the first-stage roasting temperature is 500 ℃, and the roasting time is 2 hours; the second-stage roasting temperature is 800 ℃, the roasting time is 2 hours, and the applicant of the invention proves through multiple experiments that the catalyst prepared under the conditions has the optimal structure.

Preferably, in the step (4), the mixture is naturally cooled in a tube furnace, washed with deionized water and ethanol three times respectively, and dried at 30-60 ℃ for 6-24 h.

Meanwhile, the invention discloses the nitrogen-doped Fenton-like catalyst prepared by the preparation method.

In addition, the invention discloses an application of the nitrogen-doped Fenton-like catalyst in the field of water treatment, and the application method comprises the step of adding the nitrogen-doped Fenton-like catalyst and hydrogen peroxide into waste water containing organic pollutants to oxidize and decompose the organic pollutants.

Compared with the prior art, the invention has the beneficial effects that: the invention provides a novel nitrogen-doped graphene-coated zero-valent copper nanoparticle Fenton catalyst, which is simple in preparation method and low in equipment requirement. The catalyst has a typical cladding structure, namely a Cu and N co-doped graphene structure cladding zero-valent copper. In addition, a Cu-O-C bond bridge connection is formed in the graphene-like structure, the generation of the bond bridge enables a metal Cu site to form an electron-rich center, and a graphene-like C site forms an electron-deficient center. Different types of active centers will undergo different redox reactions. Moreover, the coating structure can reduce zero-valent copper, pollutants and H₂O₂And the consumption of zero-valent copper nanoparticles is reduced by contact, and the zero-valent copper can regulate and control the electron distribution in the material.

The nitrogen-doped Fenton-like catalyst disclosed by the invention can utilize electrons in dissolved oxygen and pollutants in water to generate OOH free radicals in situ to degrade the pollutants, has a good oxidation effect on organic pollutants difficult to biodegrade, and has catalytic degradation activity and efficiency obviously higher than those of a conventional multiphase Fenton catalyst. And, the catalyst has a high H in the process of degrading the contaminants₂O₂The utilization rate and the stability are good, the metal ion elution amount is small, and the solid structure is convenient to separate from water for cyclic utilization.

Drawings

FIG. 1 is a scanning electron micrograph of example 1;

FIG. 2 is XRD patterns of example 1 and comparative example 2;

FIG. 3(a) is an XPS spectrum of O1s for NC, FIG. 3(b) is an XPS spectrum of O1s for example 1, FIG. 3(c) is an XPS spectrum of Cu2p for example 1, and FIG. 3(d) is a Cu LM2 Auger spectrum for example 1;

FIG. 4 is a graph of the degradation profile of ibuprofen, bisphenol A, phenytoin, ciprofloxacin, and diphenhydramine of example 1;

FIG. 5 is a graph of the cyclic recycle activity evaluation of example 1 for BPA degradation;

FIG. 6 shows the use of example 1 vs. H in degrading contaminants in water₂O₂Consumption test chart of (1);

FIG. 7 is a graph of the EPR signal of OOH in suspension of example 1.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific embodiments.

Example 1

The embodiment of the invention discloses a nitrogen-doped Fenton-like catalyst, and the preparation method comprises the following steps:

(1) dispersing 2g of beta-cyclodextrin and 0.6307g of copper chloride dihydrate into 60mL of methanol, and stirring for 15min to obtain a suspension A;

(2) after the step (1) is finished, adding 8g of urea into the suspension A, stirring, and evaporating to dryness in a water bath kettle at 80 ℃ to obtain a solid product A;

(3) after the step (2) is finished, drying the solid product A in a 60 ℃ oven, and uniformly grinding to obtain a solid product B;

(4) after the step (3) is finished, roasting the solid product B under the protection of nitrogen, wherein the roasting temperature of the first section is 500 ℃, and the roasting time is 2 hours; and the second-stage roasting temperature is 800 ℃, the roasting time is 2 hours, the heating rate is 5 ℃/min, the second-stage roasting process is carried out naturally, deionized water and ethanol are used for washing for 3-4 times, and then vacuum drying is carried out at 60 ℃ to obtain the nitrogen-doped Fenton-like catalyst.

Example 2

(1) dispersing 2g of beta-cyclodextrin and 0.9461g of copper chloride dihydrate into 60mL of methanol, and stirring for 15min to obtain a suspension A;

Example 3

(1) dispersing 2g of beta-cyclodextrin and 0.3154g of copper chloride dihydrate into 60mL of methanol, and stirring for 15min to obtain a suspension A;

Comparative example 1

A preparation method of a nitrogen-doped Fenton-like catalyst comprises the following steps:

(1) weighing 2g of beta-cyclodextrin and 0.6307g of copper chloride dihydrate, dispersing into 60mL of methanol solution, stirring for 15min, and evaporating to dryness at the temperature of 80 ℃ water bath to obtain a solid product A;

(2) transferring the solid product A into an oven, completely drying at 60 ℃, and uniformly grinding;

(3) under the protection of nitrogen, roasting the solid product B which is uniformly ground in a two-stage manner in a tubular furnace, wherein the first stage comprises the following steps: the roasting temperature is 500 ℃, the roasting time is 2h, and the second stage is as follows: roasting at 800 ℃ for 2h, wherein the roasting heating rate is 5 ℃/min, naturally cooling, washing with deionized water and ethanol for 3-4 times, and then placing in a vacuum oven at 60 ℃ for drying to obtain the nitrogen-doped Fenton-like catalyst.

Comparative example 2

The preparation method of the NC material synthesized without adding the copper source comprises the following steps:

(1) weighing 2g of beta-cyclodextrin and 8g of urea, dispersing into 60mL of methanol solution, stirring, and evaporating at 80 ℃ water bath temperature to obtain a solid product A;

(2) transferring the solid product A obtained by evaporation in the step (1) into an oven, completely drying at 60 ℃, and uniformly grinding to obtain a solid product B;

(3) under the protection of nitrogen, roasting the solid product B which is uniformly ground in a two-stage manner in a tubular furnace, wherein the first stage comprises the following steps: the roasting temperature is 500 ℃, the roasting time is 2h, and the second stage is as follows: roasting at 800 ℃ for 2h, wherein the roasting heating rate is 5 ℃/min, naturally cooling, washing with deionized water and ethanol for 3-4 times, and then placing in a vacuum oven at 60 ℃ for drying to obtain the NC material.

Performance testing

1. Topography and Structure testing

FIG. 1 is a scanning electron micrograph of example 1, from which it can be observed that the catalyst is a porous material.

Fig. 2 is an XRD spectrum of example 1, and from fig. 2, it can be found that, for NC not doped with Cu, the peak at the position of 24.4 ° 2 θ corresponds to the peak of the carbon (002) crystal plane, while the characteristic carbon (002) peak of example 1 is shifted to 25.2 °, indicating that the introduced Cu enters into the structure of the base material, changing the surface characteristics of the catalyst. The comparison with a standard card shows that the diffraction peaks are matched with the characteristic diffraction peaks (111), (200) and (220) of the simple substance Cu. Fig. 3(a) is an XPS spectrum of O1s of NC, fig. 3(b) is an XPS spectrum of O1s of example 1, fig. 3(c) is an XPS spectrum of Cu2p of example 1, and fig. 3(d) is a Cu LM2 auger spectrum of example 1. The peaks at 531.4eV and 532.7eV in fig. 3(a) correspond to the peaks for C ═ O and hydroxyl groups on the aromatic ring; from FIG. 3(b)It was found that the addition of the copper source resulted in an additional peak of 530.2eV, which was attributed to the formation of the copper oxide lattice, and an additional peak of 533.4eV, which corresponds to the C-O-Cu bond created by the combination of copper with the hydroxyl peak on the aromatic ring. In FIG. 3(c), the spectrum shows two main peaks at 932.4eV and 952.2eV, which are attributed to Cu2p of the sample_3/2And Cu2p_1/2In fig. 3(d), a peak at a binding energy of 569.8eV can be observed, indicating that zero-valent copper is not present on the surface of the catalyst, further indicating that zero-valent copper is encapsulated in the graphene-like material.

2. Test for catalytic Performance

0.01g of each of examples 1 to 3 was put into 50mL of a 10mg/L organic contaminant solution (pH: about 6.5), 50. mu.L of hydrogen peroxide was added thereto, and the mixture was continuously stirred in a water bath at 35 ℃ and then sampled at different time points to determine the contaminant concentration. The organic pollutant solution contains Ibuprofen (IBU), bisphenol A (BPA), Phenytoin (PHT), Ciprofloxacin (CIP) and Diphenhydramine (DP). FIG. 4 is a graph of the degradation profile of ibuprofen, bisphenol A, phenytoin, ciprofloxacin, and diphenhydramine of example 1. As can be seen from FIG. 4, the degradation rates of BPA, DP and PHT reached 100% after 60 minutes of reaction, the degradation rate of IBU reached 79% after 120 minutes of degradation, and the degradation rate of CIP reached 100%. Examples and H₂O₂The degradation effect of the organic contaminants at 60 minutes of treatment is shown in table 1.

TABLE 1 degradation ratio of organic contaminants (%)

As shown in Table 1, examples 1 to 3 and H₂O₂The combined action has better oxidative degradation effect on various organic pollutants, while the oxidative degradation effect of the comparative example 1 is relatively poor.

3. Stability test

The stability of the nitrogen-doped fenton-like catalyst disclosed by the invention in the water treatment process is studied by using the example 1, and the steps are as follows:

(1) 0.01g of example 1 was put into 50mL of a 10mg/L BPA solution, and 50. mu.L of a hydrogen peroxide solution was added thereto, and the mixture was continuously stirred in a water bath at 35 ℃;

(2) after reacting for 90 minutes, detecting the concentration of BPA in the solution;

(3) after the step (2) was completed, the catalyst was taken out, dried, and then the above operation was repeated 6 times.

Fig. 5 is a graph of evaluating the recycling activity of example 1 for BPA degradation, and it can be found from fig. 5 that after repeating for 6 times, the degradation activity of example 1 for BPA is still maintained at 99% or more, indicating that the nitrogen-doped fenton-like catalyst disclosed by the invention has good stability in the water treatment process, and can be widely applied to the actual water treatment process.

4、H₂O₂Consumption test of

FIG. 6 shows the use of example 1, H in the degradation of BPA₂O₂The consumption test chart shows that, as can be seen from fig. 6, the catalyst continuously and circularly operates for a plurality of times, the degradation activity of the catalyst to BPA is not obviously reduced, the catalyst is circularly used for 6 times, and the degradation rate of BPA is still maintained to be more than 99.0%. The above results fully reflect that the nitrogen-doped Fenton-like catalyst disclosed by the invention has good stability and can be applied to the treatment of actual micro-polluted water bodies. Fig. 7 is a graph showing EPR signals of OOH in the suspension of example 1, and it can be seen from fig. 7 that the catalyst can generate OOH using dissolved oxygen in water without adding hydrogen peroxide, and that more OOH is generated after adding BPA. By combining with the consumption diagram of hydrogen peroxide, the method can obtain that the pollutants also have a certain effect in the Fenton catalytic reaction.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a nitrogen-doped Fenton-like catalyst is characterized by comprising the following steps of:

(2) adding urea into the suspension A, stirring and evaporating to dryness to obtain a solid product A;

(3) drying the solid product A, and uniformly grinding to obtain a solid product B;

(4) and roasting, cooling, washing and drying the solid product B to obtain the nitrogen-doped Fenton-like catalyst.

2. The method according to claim 1, wherein in the step (1), the copper source is at least one of copper chloride, copper nitrate, copper acetate and copper sulfate, and the molar ratio of copper ions in the copper source to cyclodextrin is (0.2-5): 1, the solvent is methanol or ethanol.

3. The method of claim 2, wherein in step (1), the molar ratio of copper ions in the copper source to cyclodextrin is 2: 1.

4. The process according to claim 1, wherein the amount of urea added is 1 to 15g per 50 to 100mL of the solvent.

5. The process according to claim 4, wherein the amount of urea added is 8g per 60mL of the solvent.

6. The method according to claim 1, wherein in the step (2), the temperature for evaporating to dryness is 60 to 90 ℃.

7. The method according to claim 1, wherein in the step (3), the drying temperature is 50-80 ℃ and the drying time is 8-24 h.

8. The method according to claim 1, wherein in the step (4), the solid product B is calcined under an inert gas or nitrogen, and the calcination is divided into two stages, a first stage: the roasting temperature is 300-: the roasting temperature is 600-1000 ℃, and the roasting time is 1-5 h.

9. A nitrogen-doped fenton-like catalyst prepared by the process of claim 1.

10. The use of the nitrogen-doped fenton-like catalyst according to claim 9 in the field of water treatment technology, wherein in the application process, the nitrogen-doped fenton-like catalyst and hydrogen peroxide are jointly dispersed in wastewater containing organic pollutants to oxidize and decompose the organic pollutants.