CN113522289B - Cobalt-loaded carbon-based material, and preparation and application methods thereof - Google Patents

Abstract

The invention provides a preparation method of a cobalt-loaded carbon-based material for catalyzing peroxymonosulfate to degrade organic matters, which comprises the following steps: s1, dissolving cobalt acetylacetonate and dicyanodiamide in an ethanol solution, and then performing dispersion mixing treatment and drying treatment in sequence to obtain a dried product; s2, grinding the dried product to obtain a ground product; calcining the ground product under the protection of nitrogen to obtain a calcined product; s3, carrying out acid washing treatment on the calcination product at least once to obtain the cobalt-loaded carbon-based material. The cobalt-loaded carbon-based material for catalyzing the peroxymonosulfate to degrade the organic matters is obtained through the novel preparation method, can improve the activation efficiency of the peroxymonosulfate, and is high in cycle stability and low in metal leaching rate.

Description

Cobalt-loaded carbon-based material, and preparation and application methods thereof

Technical Field

The invention relates to the technical field of catalytic degradation materials, in particular to a cobalt-loaded carbon-based material, and preparation and application methods thereof.

Background

The novel pollutants are chemical substances which are strong in polarity, easy to dissolve in water, poor in volatility and not easy to biodegrade, mainly come from emerging trace organic pollutants such as antibiotics, endocrine disruptors, medicines, personal care products and the like appearing in a water body, so that the diffusion and the propagation of the novel pollutants mainly depend on the water environment and the food chain, and the novel pollutants have great threats to biological safety, human health and ecological environment. The complex structure of such substances results in that the conventional biochemical treatment method has little effect on the removal thereof, and thus it is necessary to find other effective methods for degrading such substances in wastewater.

In recent years, advanced oxidation technologies such as ozone technology, electrochemical oxidation, fenton-like reaction and the like are widely applied to degradation and removal of emerging organic pollutants. Among these advanced oxidation methods, the fenton-like reaction is considered as a method capable of continuously removing refractory organic pollutants, but the problems of low hydrogen peroxide utilization rate, narrow applicable pH range, low activity under neutral and alkaline conditions, and the like of the fenton-like reaction cause great obstacles to the application and development thereof. Compared with Fenton-like reaction, catalytic activation of Peroxymonosulfate (PMS) has attracted more attention for degradation of persistent pollutants in water with its strong oxidizing power over a wide pH range. However, the rate and efficiency of direct reaction of PMS with organic pollutants at normal temperature and pressure are extremely low, so some activation techniques must be used to excite PMS to generate active groups with strong oxidizing ability for degradation and removal of refractory organic matters.

Common PMS activation modes comprise thermal activation, ultrasonic activation, ultraviolet activation, alkali activation and the like, and the methods generally consume a large amount of extra energy or introduce chemical agents, so that the energy consumption and the cost are greatly increased. In order to solve the above problems, other approaches for efficiently activating PMS are required, and among them, carbon materials and transition metal carbon materials are widely studied for activating PMS, but there are general problems of low activation efficiency, high metal leaching rate, and the like.

In view of the above, there is a need to provide a method for preparing a cobalt-supported carbon-based material for catalyzing the degradation of organic substances by peroxymonosulfate, which solves or at least alleviates the above technical drawbacks.

Disclosure of Invention

The invention mainly aims to provide a preparation method of a cobalt-loaded carbon-based material for catalyzing peroxymonosulfate to degrade organic matters, and aims to solve the technical problems of low activation efficiency and high metal leaching rate in the prior art.

In order to achieve the above object, the present invention provides a method for preparing a cobalt-loaded carbon-based material for catalyzing the degradation of organic matters by peroxymonosulfate, comprising the steps of:

s1, dissolving cobalt acetylacetonate and dicyanodiamide in an ethanol solution, and then performing dispersion mixing treatment and drying treatment in sequence to obtain a dried product;

s2, grinding the dried product to obtain a ground product; calcining the ground product under the protection of nitrogen to obtain a calcined product;

s3, carrying out acid washing treatment on the calcination product at least once to obtain the cobalt-loaded carbon-based material.

Further, in the step S1, the mass ratio of the cobalt acetylacetonate to the dicyanodiamide is 200-400 mg:10 g.

Further, in the step S1, the dispersion mixing process includes: and carrying out ultrasonic operation on a mixed solution formed by dissolving the cobalt acetylacetonate and the dicyanodiamide in the ethanol solution at the temperature of 60-80 ℃ for more than 90 min.

Further, in the step S1, the temperature of the drying process is 60 to 80 ℃.

Further, in the step S2, the grinding process includes: firstly, pre-grinding the dried product, then adding an ethanol solution to wet the pre-ground dried product, and carrying out secondary grinding on the wetted dried product to obtain the ground product.

Further, in the step S2, the calcination process includes: placing the ground product under the protection of nitrogen, and calcining the ground product according to a set temperature rising rule;

wherein, the set heating law comprises: firstly, heating for 10min, heating the temperature from room temperature to 105 ℃, and keeping the temperature for 10 min; then, heating to 350 ℃ at the speed of 2 ℃/min, and keeping for 3 hours; heating to 650 deg.C at 2.5 deg.C/min, and maintaining for 3 hr; finally, the mixture was heated to 900 ℃ at a rate of 2 ℃/min and held for 3 hours.

Further, in step S3, the acid washing process includes:

s31, mixing the calcined product with concentrated hydrochloric acid in a container, and then standing for the first time;

s32, after the first standing, taking out the concentrated hydrochloric acid on the upper layer in the container, then mixing the aqueous solution into the container, and then standing for the second time;

s33, after the second standing, taking out the upper aqueous solution in the container.

The invention also provides a cobalt-loaded carbon-based material for catalyzing peroxymonosulfate to degrade organic matters, which is prepared by adopting the preparation method of the cobalt-loaded carbon-based material.

The invention also provides application of the cobalt-loaded carbon-based material in catalyzing peroxymonosulfate to degrade organic matters.

The invention also provides a method for degrading organic matters in sewage treatment, which is characterized in that the cobalt-loaded carbon-based material is dispersed in the sewage to be treated, and then peroxymonosulfate is added to realize the catalytic degradation of the organic matters in the sewage.

Compared with the prior art, the invention has the following advantages:

the cobalt-loaded carbon-based material for catalyzing the peroxymonosulfate to degrade organic matters is obtained through the novel preparation method, can improve the activation efficiency of the peroxymonosulfate, and has high cycle stability and low metal leaching rate; the cobalt-loaded carbon-based material is applied to catalyzing peroxymonosulfate to degrade organic matters, has extremely high activation effect on peroxymonosulfate, has sufficient active sites, and is extremely low in material consumption, the adding proportion of the cobalt-loaded carbon-based material is 0.02g/L, the catalytic degradation rate can reach 98.3% within 10min, and the catalytic degradation efficiency can still reach over 90% after the cobalt-loaded carbon-based material is recycled for 6 times; specifically, the cobalt-loaded carbon-based material and the peroxymonosulfate prepared by the method are sequentially added into a certain amount of wastewater containing organic matters according to a certain proportion, and the material activates active substances such as hydroxyl free radicals, persulfate free radicals and singlet oxygen generated by the peroxymonosulfate to degrade the organic matters so as to change the active substances into non-toxic or low-toxicity small molecular substances.

In addition, the cobalt-loaded carbon-based material prepared by the invention is a cobalt material with a carbon nano tube restricted domain, and cobalt is restricted in the carbon nano tube pore channel, so that the dissolution of cobalt is restricted; moreover, the preparation method provided by the invention is simple to operate, only the dried product needs to be ground, calcined and pickled, and the material preparation yield is high.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a transmission electron micrograph at different magnifications of the cobalt-supported carbon-based material in example 1;

fig. 2 is an elemental map of the cobalt-supported carbon-based material of example 1; wherein, (a) is a transmission electron microscope image which is not mapped, (b) is a C element mapping image, (C) is an N element mapping image, and (d) is a Co element mapping image;

FIG. 3 is an X-ray diffraction pattern of the cobalt-supported carbon-based material of example 1;

FIG. 4 is a C/C diagram of PMS degrading carbamazepine catalyzed by cobalt-supported carbon-based material in example 2 ₀ A data change map;

fig. 5 is a graph of the cycle test results of the cobalt-supported carbon-based material catalyzing PMS to degrade carbamazepine in example 3.

The implementation, functional features and advantages of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It should be noted that all the directional indicators (such as the upper and lower … …) in the embodiment of the present invention are only used to explain the relative position relationship, movement, etc. of the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Moreover, the technical solutions in the embodiments of the present invention may be combined with each other, but it is necessary to be able to be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention.

It should be understood that as a further description of the drawings, Intensity in the drawings of the specification can be expressed as Intensity, Time as Time, cycle as number of cycles, and CBZ remove as carbamazepine removal rate or degradation rate without affecting the understanding of the present invention; in addition, fig. 2 in the drawings of the specification is converted from color drawings.

The invention provides a preparation method of a cobalt-loaded carbon-based material for catalyzing peroxymonosulfate to degrade organic matters, which comprises the following steps:

s1, dissolving cobalt acetylacetonate and dicyanodiamine in an ethanol solution, and then sequentially carrying out dispersion mixing treatment and drying treatment to obtain a dried product, wherein the dried product is a pink blocky substance.

In the actual preparation process, in the step S1, the mass ratio of the cobalt acetylacetonate to the dicyanodiamide may be 200-400 mg:10g, and the ethanol solution is generally 300 mL. On the basis, the proportion of the cobalt acetylacetonate, the dicyanodiamine and the ethanol solution can be specifically 200mg to 10g to 300 mL.

The dispersion mixing treatment comprises: carrying out ultrasonic operation on a mixed solution formed by dissolving the cobalt acetylacetonate and the dicyanodiamide in the ethanol solution at the temperature of 60-80 ℃ for more than 90 min; of course, as a general option, the resulting mixed solution may be subjected to sonication for 90min only at 60 ℃.

The temperature of the drying treatment can be 60-80 ℃ until the object to be dried is dried; as a practical application, the temperature of the drying treatment can be 80 ℃, and the time of the drying treatment is 24 hours.

S2, grinding the dried product to obtain a ground product, wherein the ground product is a pink powdery substance; and calcining the ground product under the protection of nitrogen to obtain a calcined product, wherein the calcined product is a black powdery substance.

The grinding treatment comprises the following steps: firstly, pre-grinding the dried product, then adding an ethanol solution to wet the pre-ground dried product, and carrying out secondary grinding on the wetted dried product to obtain the ground product. The method specifically comprises the following steps: grinding the blocky dried product, adding a proper amount of ethanol solution, and fully grinding until the ethanol is completely volatilized to obtain the ground product.

The calcination treatment comprises: and placing the ground product under the protection of nitrogen, and calcining the ground product according to a set temperature rising rule, wherein the calcining treatment is carried out in a high-temperature high-pressure furnace.

Wherein, the set heating law comprises: firstly, heating for 10min, heating the temperature from room temperature to 105 ℃, and keeping the temperature for 10 min; then, heating to 350 ℃ at the speed of 2 ℃/min, and keeping for 3 hours; heating to 650 deg.C at 2.5 deg.C/min, and maintaining for 3 hr; finally, the mixture was heated to 900 ℃ at a rate of 2 ℃/min and held for 3 hours.

S3, carrying out acid washing treatment on the calcination product at least once to obtain the cobalt-loaded carbon-based material.

Wherein the acid washing treatment comprises the following steps:

s31, mixing the calcined product with concentrated hydrochloric acid in a container, and then standing for the first time;

s32, after the first standing, taking out the upper concentrated hydrochloric acid in the container (i.e. completely taking out the concentrated hydrochloric acid in the container), mixing the aqueous solution into the container, and then standing for the second time;

s33, after the second standing, taking out the upper aqueous solution in the container (i.e. taking out the water in the container as much as possible).

The acid washing treatment specifically comprises the steps of uniformly mixing the calcined product with concentrated hydrochloric acid, standing for 30 minutes, taking out the upper layer of concentrated hydrochloric acid, adding 10mL of deionized water, fully oscillating, uniformly mixing, standing for 20 minutes, and taking out the upper layer of deionized water; wherein, during the acid washing treatment, the ratio of the calcined product to the concentrated hydrochloric acid can be 60mg:5 mL. In addition, when concentrated hydrochloric acid is added to the vessel, the vessel should be slowly added and shaken to uniformly mix the calcined product with the concentrated hydrochloric acid, thereby preventing explosion.

It should be noted that the acid cleaning process may be a single process of the steps S31-S33, or two times of the steps S31-S33 may be defined as a single acid cleaning process, and in an actual experimental process, two times of the steps S31-S33 are generally defined as a single acid cleaning process, that is, concentrated hydrochloric acid cleaning, aqueous solution cleaning, concentrated hydrochloric acid cleaning, and aqueous solution cleaning are sequentially performed as a single acid cleaning process.

However, in the present invention, in order to distinguish the number of times of pickling, one process of the steps S31 to S33 is defined as one pickling process. Namely, concentrated hydrochloric acid cleaning and aqueous solution cleaning are defined as one pickling treatment.

When the single process of steps S31-S33 is defined as a single pickling process, the number of pickling processes may be selected according to actual conditions, and, of course, the number of pickling processes may be generally 10 to 12 in order to enable thorough cleaning.

The cobalt-supported carbon-based material prepared by the embodiment can be used for catalyzing peroxymonosulfate to degrade organic matters, greatly improves the degradation efficiency of the organic matters, and can avoid the dissolution of cobalt. Therefore, the invention creatively researches a new preparation method, and the cobalt-loaded carbon-based material with catalytic degradation effect on organic matters can be obtained through the new preparation method.

It is to be understood that, in the present invention, the cobalt-supported carbon-based material is prepared by using cobalt acetylacetonate and dicyanodiamide as raw materials, and polymerizing the dicyanodiamide to form a substrate by high-temperature and high-pressure calcination while generating vacancy defects to fix cobalt in the substrate material. The finally formed cobalt-loaded carbon-based material is of a carbon nanotube structure, and the structure is beneficial to limiting cobalt and reducing leaching of the cobalt; the cobalt-loaded carbon-based material is a cobalt material of the carbon nano tube confinement, so that cobalt is confined in the pore canal of the carbon nano tube, and the dissolution of the cobalt is limited. In addition, the presence of N in the cobalt-supported carbon-based material can create vacancy defects, embedding cobalt therein, enhancing the bonding between cobalt and carbon nanotubes.

In the process of catalyzing PMS (peroxymonosulfate) to degrade organic pollutants, the cobalt-loaded carbon-based material passes through an electron transfer process between cobalt and a carbon nano tube, the cobalt is changed from divalent to trivalent and then from trivalent to divalent in a circulating process, PMS is excited to generate active substances with strong oxidation capacity, such as singlet oxygen, hydroxyl free radicals, sulfate free radicals and the like, and the active substances can be used for oxidative degradation of organic matters and are changed into small molecular substances with no toxicity or low toxicity.

In order to efficiently degrade organic pollutants in sewage, the invention also provides a cobalt-supported carbon-based material for catalyzing peroxymonosulfate to degrade organic matters, which is prepared by the preparation method of the cobalt-supported carbon-based material according to any embodiment.

The invention also provides application of the cobalt-supported carbon-based material in catalyzing peroxymonosulfate to degrade organic matters.

Based on the application of the cobalt-loaded carbon-based material in catalyzing peroxymonosulfate to degrade organic matters, the invention also provides a method for degrading organic matters in sewage treatment, wherein the cobalt-loaded carbon-based material is dispersed in sewage to be treated, and peroxymonosulfate is added to realize catalytic degradation of the organic matters in the sewage. The cobalt-loaded carbon-based material and the peroxymonosulfate are added into the sewage to be treated, PMS is activated to generate active substances such as hydroxyl free radicals, persulfate free radicals, singlet oxygen and the like, so that organic matters in the sewage are degraded and changed into small molecular substances which are non-toxic or have low toxicity.

To facilitate a further understanding of the invention, reference will now be made to the following examples:

example 1

A preparation method of a cobalt-loaded carbon-based material for catalyzing peroxymonosulfate to degrade organic matters comprises the following steps:

1. dissolving 200mg of cobalt acetylacetonate and 10g of dicyanodiamide in 300mL of ethanol, performing ultrasonic treatment at 60 ℃ for 90min, and then placing the solution in an oven to be dried at the temperature of 80 ℃;

2. pouring the dried substances into a mortar, grinding the blocky substances, adding a proper amount of ethanol, grinding uniformly, and stopping grinding until the ethanol is completely volatilized to obtain powdery substances;

3. and (2) calcining the powder substance obtained by grinding in a high-temperature high-pressure furnace with nitrogen protection, wherein the temperature rising rule of the calcination is as follows: first, the temperature is raised from room temperature to 105 ℃ for 10min and kept for 10 min; then heating to 350 ℃ at the speed of 2 ℃/min, and keeping for 3 hours; then heating to 650 ℃ at the speed of 2.5 ℃/min, and keeping for 3 hours; heating to 900 deg.C at 2 deg.C/min and maintaining for 3 hr;

4. the product obtained after calcination was repeatedly washed with concentrated hydrochloric acid (i.e., by the acid washing treatment in the above embodiment) to wash away the metal clusters and large particles on the surface of the material, and the final product obtained was designated as a Co — N — C material, i.e., a cobalt-supported carbon-based material in the present invention.

The cobalt-supported carbon-based material prepared in example 1 is a carbon nanotube-confined cobalt material, and can be understood with reference to fig. 1 and 2; in addition, the morphology of cobalt in the prepared cobalt-supported carbon-based material can be understood with reference to fig. 3.

Example 2

An assay for catalyzing PMS (peroxymonosulfate) degradation of an organic substance, comprising:

1. adding 2mg of the cobalt-supported carbon-based material prepared in example 1 to 100mL of the carbamazepine solution (10ppm), and performing ultrasonic treatment for 5min to uniformly disperse the cobalt-supported carbon-based material in the carbamazepine solution; then, carrying out subsequent experimental steps under the stirring state, wherein the rotating speed is 300 r/min; adding 1mL of 0.1mol/L PMS solution into the solution and starting timing;

2. taking appropriate amount of solution with 5mL injector at 1min, 2min, 3min, 5min, 7min, and 10min respectively, filtering with 0.22 μm filter head, and adding into 2mL liquid chromatography sample bottle filled with 20 μ L ethanol;

3. and measuring the samples by using liquid chromatography, recording corresponding peak areas, converting the peak areas into the concentration of the carbamazepine according to a standard curve, and calculating the degradation rate of the carbamazepine.

4. The final test results are shown in the following table, wherein C/C ₀ The current carbamazepine concentration C and the initial carbamazepine concentration C ₀ (note the symbol C of the initial carbamazepine concentration) ₀ Distinguished from the chemical symbol Co of cobalt), as can be seen from the following table and fig. 4, when PMS is catalyzed to degrade carbamazepine using the cobalt-supported carbon-based material prepared in example 1, the degradation rate may reach 98.3% within 10 minutes.

Time

1min

2min

3min

5min

7min

10min

C/C 0

0.296

0.194

0.144

0.068

0.037

0.017

Rate of degradation

70.4％

80.6％

85.6％

93.2％

96.3％

98.3％

Example 3

A cycle test run to catalyze PMS (peroxymonosulfate) degradation of organic matter, comprising:

1. the obtained cobalt-supported carbon-based material was subjected to the test of repeating the use of the cobalt-supported carbon-based material prepared in example 1 by the method in example 2, and the number of repetitions was 6. Then, the degradation efficiency of the cobalt-supported carbon-based material catalyzing PMS to degrade carbamazepine was measured at each use.

2. And comparing the data of the degradation efficiency measured and calculated when the cobalt-loaded carbon-based material is catalyzed for 10min in each use process. As shown in the following table and fig. 5, the final results indicate that the cobalt-supported carbon-based material prepared in example 1 can still achieve a degradation efficiency of 90% or more on carbamazepine after being recycled six times.

1 time of	2 times (one time)	3 times of	4 times (twice)	5 times of	6 times of
						98.3％	97.6％	97.2％	96.1％	95.4％	95.1％

In the above technical solutions, the above are only preferred embodiments of the present invention, and the technical scope of the present invention is not limited thereby, and all the technical concepts of the present invention include the claims of the present invention, which are directly or indirectly applied to other related technical fields by using the equivalent structural changes made in the content of the description and the drawings of the present invention.

Claims (5)

1. The application of the cobalt-loaded carbon-based material in catalyzing peroxymonosulfate to degrade organic matters is characterized in that the organic matters are carbamazepine;

the preparation method of the cobalt-loaded carbon-based material comprises the following steps:

s1, dissolving cobalt acetylacetonate and dicyanodiamide in an ethanol solution, and then performing dispersion mixing treatment and drying treatment in sequence to obtain a dried product;

the mass ratio of the cobalt acetylacetonate to the dicyanodiamide is 200-400 mg:10 g;

s2, grinding the dried product to obtain a ground product; calcining the ground product under the protection of nitrogen to obtain a calcined product;

the heating law set in the calcination treatment comprises the following steps: firstly, heating for 10min, heating the temperature from room temperature to 105 ℃, and keeping the temperature for 10 min; then, heating to 350 ℃ at the speed of 2 ℃/min, and keeping for 3 hours; heating to 650 deg.C at 2.5 deg.C/min, and maintaining for 3 hr; finally, heating to 900 ℃ at the speed of 2 ℃/min, and keeping for 3 hours;

s3, carrying out acid washing treatment on the calcination product at least once to obtain the cobalt-loaded carbon-based material.

2. The use according to claim 1, wherein in the step S1, the dispersive mixing process includes: and carrying out ultrasonic operation on a mixed solution formed by dissolving the cobalt acetylacetonate and the dicyanodiamide in the ethanol solution at the temperature of 60-80 ℃ for more than 90 min.

3. The use according to claim 1, wherein in the step S1, the temperature of the drying process is 60-80 ℃.

4. The use according to claim 1, wherein in the step S2, the grinding process comprises: firstly, pre-grinding the dried product, then adding an ethanol solution to wet the pre-ground dried product, and carrying out secondary grinding on the wetted dried product to obtain the ground product.

5. The use according to any one of claims 1 to 4, wherein in step S3, the acid washing treatment comprises:

s31, mixing the calcined product with concentrated hydrochloric acid in a container, and then standing for the first time;

s32, after the first standing, taking out the concentrated hydrochloric acid on the upper layer in the container, then mixing the aqueous solution into the container, and then standing for the second time;

s33, after the second standing, taking out the upper aqueous solution in the container.

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