阅读说明：本技术 一种掺氮钛炭复合型催化剂及其制备方法和应用 (Nitrogen-doped titanium-carbon composite catalyst and preparation method and application thereof ) 是由 崔燕 黄张根 曾泽泉 于 2019-08-22 设计创作，主要内容包括：本发明属于废水处理领域,一种掺氮钛炭复合型催化剂,以钛酸丁酯为钛源,尿素为氮源,通过溶胶-凝胶法,将活性炭作为载体添加至溶胶中,烘干后经惰性气氛煅烧和空气预氧化,制备出掺氮炭钛复合型催化剂N-TiO<Sub>2</Sub>/AC。本发明还涉及掺氮钛炭复合型催化剂制备方法及应用。本发明制备的掺氮炭钛复合型催化剂N-TiO<Sub>2</Sub>/AC,可将其光催化活性延伸至可见光区,并且可以高效活化过硫酸盐产生自由基降解煤化工废水。(The invention belongs to the field of wastewater treatment, and discloses a nitrogen-doped titanium-carbon composite catalyst, which is prepared by adding activated carbon serving as a carrier into sol by using butyl titanate as a titanium source and urea as a nitrogen source through a sol-gel method, drying, calcining in inert atmosphere and pre-oxidizing in air 2 and/AC. The invention also relates to a preparation method and application of the nitrogen-doped titanium-carbon composite catalyst. The nitrogen-doped carbon-titanium composite catalyst N-TiO prepared by the invention 2 the/AC can extend the photocatalytic activity to a visible light region, and can efficiently activate persulfate to generate free radicals to degrade coal chemical wastewater.)

1. A nitrogen-doped titanium-carbon composite catalyst is characterized in that: adding activated carbon serving as a carrier into sol by using butyl titanate as a titanium source and urea as a nitrogen source through a sol-gel method, drying, calcining in inert atmosphere and pre-oxidizing in air to prepare the N-TiO composite nitrogen-doped carbon-titanium catalyst₂/AC。

2. A preparation method of a nitrogen-doped titanium-carbon composite catalyst is characterized by comprising the following steps: the method comprises the following steps

Dissolving butyl titanate in absolute ethyl alcohol, adding acetylacetone, mixing and uniformly stirring to obtain a solution A; uniformly stirring urea, absolute ethyl alcohol, distilled water and acetylacetone, and adjusting the pH to 2-3 by hydrochloric acid to obtain a solution B; dropwise adding the solution B into the solution A under the stirring condition to obtain light yellow transparent sol;

secondly, adding the pretreated active carbon into the transparent sol, uniformly stirring and drying;

step three, roasting the dried article in the step two in a nitrogen atmosphere, oxidizing the roasted article in an air atmosphere, taking out the roasted article and grinding the oxidized article into powder to obtain the nitrogen-doped carbon titanium composite catalyst N-TiO₂/AC。

3. The preparation method of the nitrogen-doped titanium-carbon composite catalyst according to claim 2, which is characterized in that: and the pretreatment process of the activated carbon in the second step comprises the steps of stirring and washing the activated carbon by using hydrofluoric acid with the volume percentage of 10%, filtering the activated carbon, stirring and washing the filtered activated carbon by using nitric acid with the volume percentage of 10%, filtering the activated carbon, stirring and washing the filtered activated carbon by using deionized water to be neutral, and drying the washed activated carbon.

4. The preparation method of the nitrogen-doped titanium-carbon composite catalyst according to claim 2, which is characterized in that: in the first step, the volume ratio of the butyl titanate, the absolute ethyl alcohol and the acetylacetone in the solution A is 1:2:1, and the volume ratio of the absolute ethyl alcohol, the distilled water and the acetylacetone in the solution B is 1:22: 1.

5. The preparation method of the nitrogen-doped titanium-carbon composite catalyst according to claim 2, which is characterized in that: the mass ratio of the mass of the nitrogen contained in the urea in the solution B to the total titanium contained in the butyl titanate in the solution A is 0.75-3, and the mass ratio of the mass of the activated carbon to the total titanium contained in the butyl titanate in the solution A is 0.15-4.

6. The preparation method of the nitrogen-doped titanium-carbon composite catalyst according to claim 5, which is characterized in that: the mass ratio of the mass of the activated carbon to the total titanium content of the butyl titanate in the solution A is 0.15-1.5.

7. The preparation method of the nitrogen-doped titanium-carbon composite catalyst according to claim 2, which is characterized in that: in the third step, the article dried in the second step is roasted for 3h at the temperature of 400 ℃ and 600 ℃ in the nitrogen atmosphere, and then oxidized for 2h at the temperature of 180 ℃ and 200 ℃ in the air atmosphere.

8. The application of the nitrogen-doped titanium-carbon composite catalyst is characterized in that: the visible light catalytic and advanced oxidation synergistic degradation method is used for degrading coal chemical wastewater.

9. The application of the nitrogen-doped titanium-carbon composite catalyst according to claim 8, which is characterized in that: nitrogen doped carbon-titanium composite catalyst N-TiO₂and/AC is put into phenol wastewater, physical adsorption is carried out until the phenol wastewater is saturated, potassium persulfate is added, and visible light is utilized to carry out photocatalysis and advanced oxidation synergistic degradation on coal chemical wastewater.

10. The application of the nitrogen-doped titanium-carbon composite catalyst according to claim 9, which is characterized in that: the concentration of the target pollutant phenol is 20-160 mg/L.

11. The application of the nitrogen-doped titanium-carbon composite catalyst according to claim 9, which is characterized in that: the concentration of the potassium persulfate is 2.5-10 g/L.

12. The application of the nitrogen-doped titanium-carbon composite catalyst according to claim 9, which is characterized in that: the degradation reaction temperature is 15-45 ℃.

13. The application of the nitrogen-doped titanium-carbon composite catalyst as claimed in claim 9, wherein the nitrogen-doped titanium-carbon composite catalyst comprises the following components in percentage by weight: the pH value of the phenol wastewater is adjusted to 3-11 in the degradation process.

14. The application of the nitrogen-doped titanium-carbon composite catalyst as claimed in claim 13, wherein the nitrogen-doped titanium-carbon composite catalyst comprises the following components in percentage by weight: the pH value of the phenol wastewater is adjusted to 3-9 in the degradation process.

Technical Field

The invention belongs to the field of wastewater treatment, and particularly relates to a nitrogen-doped titanium-carbon composite catalyst for visible-light catalysis and advanced oxidation, and a preparation method and application thereof.

Technical Field

The coal chemical industry wastewater is typical industrial wastewater containing refractory organic matters, the types of pollutants are more than 240, the pollutants comprise high-toxicity pollutants such as phenols, polycyclic aromatic compounds, heterocyclic compounds containing nitrogen, oxygen and sulfur, and the like, and the high-toxicity pollutants still contain a large amount of refractory organic matters after being treated by a traditional biochemical method. However, the existing coal chemical wastewater treatment technology is not perfect enough, and the wastewater can not be discharged after reaching the standard. Therefore, the technology for efficiently degrading the coal chemical wastewater is urgent.

TiO₂Has been widely applied to the degradation of coal chemical industry wastewater as a photocatalyst, and has been found through a large amount of experimental researches, for example, the domestic published patents CN101444724A and CN 105671486A, CN 108906107A adopt doped non-metallic elements such as N, C, S, B, F, Cl and the like to successfully degrade nano TiO₂Extend the photoresponse range of the non-metal doped TiO into the visible region₂The photocatalytic material has photocatalytic activity under irradiation of visible light.

Using suspended TiO₂The problems of easy inactivation, easy agglomeration, difficult separation and the like exist, the domestic published patent CN 102527365A, CN109264813A and the like introduces the activated carbon as a photocatalytic carrier, the activated carbon has larger specific surface area and pore diameter, and can inhibit TiO₂Agglomeration of the grains to produce TiO₂The phase change activation energy is increased, the temperature of the crystal transformation is increased, and TiO is favorably treated₂Uniformly disperse and improve TiO₂Photocatalytic efficiency. But due to TiO₂Hole and electron pairs are easy to recombine, so that the photocatalysis efficiency is low. In recent years, many researches have found that persulfate is used as an electron acceptor, can not only separate holes and electron pairs and improve photocatalytic activity, but also can generate sulfate radicals and strong-oxidizing substances of hydroxyl radicals, and is applied to advanced treatment of wastewater in domestic published patents CN108993472A, CN104399516B and the like.

However, at present, no invention relates to a catalyst and a technology for degrading phenol by introducing nitrogen into titanium dioxide, compounding the titanium dioxide with active carbon and utilizing visible light catalysis in cooperation with persulfate advanced oxidation. In order to degrade the coal chemical wastewater more efficiently, the nitrogen-doped titanium-carbon composite catalyst is invented and applied to visible light catalysis and advanced oxidation treatment of the coal chemical wastewater, so that the efficient degradation of the wastewater is realized.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to utilize a visible light energy source to realize the efficient degradation of the coal chemical wastewater.

The technical scheme adopted by the invention is as follows: a nitrogen-doped titanium-carbon composite catalyst is prepared from butyl titanate as titanium source, urea as nitrogen source, activated carbon as carrier, sol-gel method, baking, calcining in inertial atmosphere and pre-oxidizing in air₂/AC。

The preparation method of the nitrogen-doped titanium-carbon composite catalyst comprises the following steps

Dissolving butyl titanate in absolute ethyl alcohol, adding acetylacetone, mixing and uniformly stirring to obtain a solution A; uniformly stirring urea, absolute ethyl alcohol, distilled water and acetylacetone, and adjusting the pH to 2-3 by hydrochloric acid to obtain a solution B; dropwise adding the solution B into the solution A under the stirring condition to obtain light yellow transparent sol;

secondly, adding the pretreated active carbon into the transparent sol, uniformly stirring and drying;

step three, roasting the dried article in the step two in a nitrogen atmosphere, oxidizing the roasted article in an air atmosphere, taking out the roasted article and grinding the oxidized article into powder to obtain the nitrogen-doped carbon titanium composite catalyst N-TiO₂/AC。

And the pretreatment process of the activated carbon in the second step comprises the steps of stirring and washing the activated carbon by using hydrofluoric acid with the volume percentage of 10%, filtering the activated carbon, stirring and washing the filtered activated carbon by using nitric acid with the volume percentage of 10%, filtering the activated carbon, stirring and washing the filtered activated carbon by using deionized water to be neutral, and drying the washed activated carbon.

In the first step, the volume ratio of the butyl titanate, the absolute ethyl alcohol and the acetylacetone in the solution A is 1:2:1, and the volume ratio of the absolute ethyl alcohol, the distilled water and the acetylacetone in the solution B is 1:22: 1.

The mass ratio of the mass of the nitrogen contained in the urea in the solution B to the total titanium contained in the butyl titanate in the solution A is 0.75-3, and the mass ratio of the mass of the activated carbon to the total titanium contained in the butyl titanate in the solution A is 0.15-4.

The mass ratio of the mass of the activated carbon to the total titanium content of the butyl titanate in the solution A is 0.15-1.5

In the third step, the article dried in the second step is roasted for 3h at the temperature of 400 ℃ and 600 ℃ in the nitrogen atmosphere, and then oxidized for 2h at the temperature of 180 ℃ and 200 ℃ in the air atmosphere.

An application of a nitrogen-doped titanium-carbon composite catalyst is used for degrading coal chemical wastewater by visible light catalysis in cooperation with advanced oxidation.

Nitrogen doped carbon-titanium composite catalyst N-TiO₂Phenol wastewater (nitrogen-doped carbon-titanium composite catalyst N-TiO) input by AC₂The concentration of/AC is 0.5-2 g/l), the potassium persulfate (PS for short) is added after physical adsorption is carried out to saturation, and visible light is utilized to carry out photocatalysis synergistic advanced oxidation degradation on the coal chemical industry wastewater.

The concentration of the target pollutant phenol is 20-160 mg/L.

The concentration of the potassium persulfate is 2.5-10 g/L.

The degradation reaction temperature is 15-45 ℃.

The pH value of the phenol wastewater is adjusted to 3-11 in the degradation process.

The pH value of the phenol wastewater is adjusted to be 3-9 in the degradation process.

The invention has the beneficial effects that: 1. the nitrogen-doped titanium-carbon composite photocatalyst can greatly improve visible light (xenon light source, wavelength)>400 nm). 2, the phenol is degraded by photocatalysis and potassium persulfate advanced oxidation, and the degradation rate is obviously improved compared with the degradation rate by a single method. 3. The invention mixes N-TiO₂The photocatalytic oxidation of the/AC is combined with the advanced oxidation of activating persulfate to generate sulfate radicals and hydroxyl radicals, so that the problem of insufficient utilization rate of sunlight is solved, the persulfate is combined to degrade the coal chemical wastewater in a synergistic manner, and the treatment efficiency is improved.

Drawings

FIG. 1 is a graph showing the effect of phenol removal under various conditionsShows a curve of the removal rate of phenol wastewater which is oxidized and degraded by persulfate alone,represents N-TiO₂A removal rate curve of AC visible light catalytic degradation phenol wastewater,represents N-TiO₂A removal rate curve of phenol wastewater degraded by the cooperation of AC visible light catalysis and advanced oxidation;

FIG. 2 is a graph showing the effect of different catalysts on the removal of phenol by the synergistic advanced oxidation under the irradiation of visible light,shows a curve of the removal rate of phenol wastewater which is oxidized and degraded by persulfate alone,represents TiO₂Under the irradiation of visible light, the removal rate curve of phenol wastewater by the synergistic advanced oxidation,represents N-TiO₂Under the irradiation of visible light, the removal rate curve of phenol wastewater by the synergistic advanced oxidation,represents TiO₂The removal rate curve of phenol wastewater by the cooperation of AC and advanced oxidation under the irradiation of visible light,shows the curve of the removal rate of phenol wastewater by the synergistic advanced oxidation of N-TiO2/AC under the irradiation of visible light.

Detailed Description

The nitrogen-doped titanium-carbon composite catalyst prepared by the invention can efficiently and rapidly oxidize phenol wastewater under the synergistic action of visible light catalysis and persulfate advanced oxidation, and the removal rate of organic matters is improved.

A nitrogen-doped titanium-carbon composite catalyst is prepared by taking butyl titanate as a titanium source and urea as a nitrogen source, and adding activated carbon serving as a carrier into a mixed solution by a sol-gel methodDrying in sol, calcining in inert atmosphere and pre-oxidizing in air to obtain N-TiO composite N-doped carbon-titanium catalyst₂/AC。

Preparation method of nitrogen-doped titanium-carbon composite catalyst

Pretreating activated carbon, namely stirring and washing the activated carbon for 10-12h by using 10% hydrofluoric acid by volume percentage, filtering, adding 10% nitric acid by volume percentage, stirring and washing for 10-12h, then washing to be neutral by using deionized water, and drying for later use

Dissolving 20 ml of butyl titanate in 40 ml of absolute ethyl alcohol, adding 20 ml of acetylacetone, mixing and uniformly stirring to obtain solution A; uniformly stirring and mixing urea with the mass of a g, 20 ml of absolute ethyl alcohol, 440 ml of deionized water and 20 ml of acetylacetone, and adjusting the pH to 2.5 by hydrochloric acid to obtain a solution B; the solution B is dropwise added into the solution A under the stirring condition, and light yellow transparent sol is obtained. B g of acidified active carbon is added, stirred for 3 hours and dried at 100 ℃. Grinding the dried sample, putting the ground sample into a tube furnace, and keeping the temperature at C DEG C to obtain N₂Roasting in atmosphere for 3 hr, pre-oxidizing in air at 200 deg.c for 2 hr, taking out and grinding into powder to obtain N-TiO₂/AC。

The operation steps of the catalyst for degrading phenol by photocatalysis and advanced oxidation are as follows:

placing 100 ml of phenol wastewater with the concentration of e mg/L into a reactor at the temperature of d ℃, and adding N-TiO₂and/AC, the concentration of the catalyst in the wastewater is g/L, the pH is adjusted to f, the reaction is initially stirred for 30min in a dark state to reach adsorption equilibrium, then potassium persulfate with the concentration of h g/L is added, the phenol wastewater is degraded under the irradiation of visible light, the phenol concentration is measured by liquid chromatography after 60 min, and the degradation rate is calculated.

The following detailed description will be made in conjunction with embodiments and the accompanying drawings.