阅读说明：本技术 超薄富氮石墨相氮化碳纳米片负载的气凝胶可见光催化剂及其制备方法和应用 (Ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-driven photocatalyst and preparation method and application thereof ) 是由 张长 马驰 魏婧婧 杨旭 王倓倓 杨凯华 谭畅 于 2021-09-07 设计创作，主要内容包括：本发明公开了一种超薄富氮石墨相氮化碳纳米片负载的气凝胶可见光催化剂及其制备方法和应用,该催化剂包括明胶气凝胶以及镶嵌在其内部和负载于其表面的超薄富氮石墨相氮化碳纳米片。其制备方法包括：将超薄富氮石墨相氮化碳纳米片、明胶、起泡剂与水制成前驱体,冷冻干燥,烧结,得到相应的催化剂。本发明催化剂具有自悬浮、便于回收、形状可调、不含有毒有害元素、对可见光吸收性能好、光催化性能优异等优点,是一种性能优异的新型气凝胶可见光催化剂,可广泛用于处理抗生素废水,且能够有效去除水体中的抗生素,使用价值高,应用前景好；同时,其制备方法具有工艺简单、操作方便、成本低廉、安全环保等优点,适合于大规模制备,利于工业化应用。(The invention discloses an aerogel visible-light-induced photocatalyst loaded by ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets and a preparation method and application thereof. The preparation method comprises the following steps: preparing a precursor from the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet, gelatin, a foaming agent and water, and freeze-drying and sintering to obtain the corresponding catalyst. The catalyst has the advantages of self-suspension, convenient recovery, adjustable shape, no toxic or harmful elements, good visible light absorption performance, excellent photocatalytic performance and the like, is a novel aerogel visible-light catalyst with excellent performance, can be widely used for treating antibiotic wastewater, can effectively remove antibiotics in water, and has high use value and good application prospect; meanwhile, the preparation method has the advantages of simple process, convenience in operation, low cost, safety, environmental friendliness and the like, is suitable for large-scale preparation, and is beneficial to industrial application.)

1. The visible light catalyst is characterized by comprising ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets and gelatin aerogel, wherein the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets are embedded in the gelatin aerogel and loaded on the surface of the gelatin aerogel.

2. The ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible light catalyst of claim 1, wherein the mass ratio of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets to the gelatin aerogel is 0.5-4: 7; the thickness of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet is 0.2-0.4 nm; the shape of the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is one of granular shape, blocky shape, cake shape and spherical shape.

3. A method of making the ultra-thin nitrogen-rich graphitic carbon nitride nanosheet-supported aerogel visible light catalyst of claim 1 or 2, comprising the steps of:

s1, mixing the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, gelatin, a foaming agent and water, and stirring to obtain a precursor;

and S2, freeze-drying and sintering the precursor obtained in the step S1 to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible light catalyst.

4. The preparation method according to claim 3, wherein in step S1, the mass ratio of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets, the gelatin and the foaming agent is 0.05-0.40: 0.75: 0.0823; the foaming agent is at least one of sodium dodecyl sulfate, hexadecyl trimethyl ammonium bromide and sodium dodecyl benzene sulfonate.

5. The method of manufacturing of claim 4, wherein in step S1, the method of manufacturing ultrathin nitrogen-enriched graphite phase carbon nitride nanosheets includes the steps of:

(1) carrying out thermal polycondensation reaction on 3-amino-1, 2, 4-triazole to obtain blocky nitrogen-rich graphite phase carbon nitride;

(2) and (2) placing the blocky nitrogen-rich graphite phase carbon nitride obtained in the step (1) in a solvent, ultrasonically stripping, centrifuging, taking supernatant, and filtering to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet.

6. The method according to claim 5, wherein in the step (1), the temperature rise rate during the thermal polycondensation reaction is 2 ℃/min to 10 ℃/min; the temperature of the thermal polycondensation reaction is 450-500 ℃; the time of the thermal polycondensation reaction is 3-4 h;

in the step (2), the solvent is at least one of isopropanol, water and ethanol; the power of the ultrasonic stripping is 300-800W; the frequency of the ultrasonic stripping is 40 KHz; the ultrasonic stripping time is 8-12 h; the rotating speed of the centrifugation is 3000 rpm-4000 rpm, and the centrifugation time is 10 min-15 min.

7. The production method according to any one of claims 3 to 6, wherein in step S1, the rotation speed of the stirring is 2500rpm to 3000rpm, and the stirring time is 60min to 90 min;

in step S2, the freeze drying time is 24-28 h; the sintering is carried out in a nitrogen atmosphere; the heating rate in the sintering process is 2-5 ℃/min; the sintering temperature is 100-200 ℃; the sintering time is 3-5 h.

8. Application of the ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst according to claim 1 or 2 or the ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst prepared by the preparation method according to any one of claims 3 to 7 in treatment of antibiotic wastewater.

9. Use according to claim 8, characterized in that it comprises the following steps: mixing the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets with the antibiotic wastewater, stirring, and carrying out photocatalytic degradation under the illumination condition to complete the treatment of the antibiotic wastewater.

10. The use according to claim 9, wherein the amount of the aerogel visible light catalyst supported by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets added is 3.75 to 5.50g per liter of antibiotic wastewater; the initial concentration of the antibiotics in the antibiotic wastewater is 10 mg/L-20 mg/L; the antibiotic is tetracycline hydrochloride and/or oxytetracycline hydrochloride; the stirring time is 30-60 min; the time of the photocatalytic degradation is 1-2 h.

Technical Field

The invention relates to an aerogel visible light catalyst, in particular to an ultrathin nitrogen-rich graphite phase carbon nitride nanosheet loaded aerogel visible light catalyst and a preparation method and application thereof.

Background

With the rapid development of material science, the photocatalytic technology is also rapidly developed as a green chemical treatment technology. At present, thousands of photocatalysts are successfully developed, but the application of the photocatalytic technology is slowly advanced. The factors limiting the practical application of the photocatalytic technology mainly include the following three points: 1) the main focus of developers is to develop a high-performance nano powder photocatalyst, the nano powder material has good dispersibility in water, but high economic cost is brought to subsequent solid-liquid separation, the catalyst is difficult to recycle, and the content of effluent particles is high; 2) part of developed photocatalysts contain toxic and harmful elements, such as heavy metals and halogens in CdS, BiOX (X ═ F, Cl, Br and I) and the like, and can bring secondary pollution when applied to water treatment; 3) the developed part of the photocatalyst has low utilization efficiency on solar spectrum, can only absorb ultraviolet spectrum part in the solar spectrum, and has low utilization ratio on visible light. In addition, the existing aerogel composite photocatalyst still has the defects of poor light absorption capacity, poor photocatalytic activity, poor reusability, environmental pollution and the like, and meanwhile, in the corresponding method for preparing the aerogel composite photocatalyst, acid, alkali or other chemical reagents are often used for treatment, so that the defects of complicated preparation process, more related chemicals, easy secondary pollution and the like exist, and the wide application of the aerogel composite photocatalyst is greatly limited. Therefore, the obtained ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light catalyst is self-suspending, convenient to recover, adjustable in shape, free of toxic and harmful elements, good in visible-light absorption performance and excellent in photocatalytic performance, and the matched preparation method with simple process, convenience in operation, low cost, safety and environment friendliness is very important for improving the application range of the aerogel composite photocatalyst and realizing effective removal of antibiotics in wastewater.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an aerogel visible-light-driven photocatalyst which is self-suspended, convenient to recover, adjustable in shape, free of toxic and harmful elements, good in visible-light absorption performance and excellent in photocatalytic performance and is loaded by ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets, a preparation method of the aerogel visible-light-driven photocatalyst and application of the aerogel visible-light-driven photocatalyst in treatment of antibiotic wastewater.

In order to solve the technical problems, the invention adopts the following technical scheme:

the visible photocatalyst comprises ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets and gelatin aerogel, wherein the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets are embedded in the gelatin aerogel and are loaded on the surface of the gelatin aerogel.

The ultrathin nitrogen-rich graphite phase carbon nitride nanosheet loaded aerogel visible light catalyst is further improved, wherein the mass ratio of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets to the gelatin aerogel is 0.5-4: 7; the thickness of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet is 0.2-0.4 nm; the shape of the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is one of granular shape, blocky shape, cake shape and spherical shape.

As a general technical concept, the invention also provides a preparation method of the aerogel visible-light-driven photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, which comprises the following steps:

s1, mixing the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, gelatin, a foaming agent and water, and stirring to obtain a precursor;

and S2, freeze-drying and sintering the precursor obtained in the step S1 to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible light catalyst.

In the step S1, the mass ratio of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet to the gelatin to the foaming agent is 0.05-0.40: 0.75: 0.0823; the foaming agent is at least one of sodium dodecyl sulfate, hexadecyl trimethyl ammonium bromide and sodium dodecyl benzene sulfonate.

In step S1, the method for preparing ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets further includes the following steps:

(1) carrying out thermal polycondensation reaction on 3-amino-1, 2, 4-triazole to obtain blocky nitrogen-rich graphite phase carbon nitride;

(2) and (2) placing the blocky nitrogen-rich graphite phase carbon nitride obtained in the step (1) in a solvent, ultrasonically stripping, centrifuging, taking supernatant, and filtering to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet.

The preparation method is further improved, in the step (1), the heating rate is 2-10 ℃/min in the thermal polycondensation reaction process; the temperature of the thermal polycondensation reaction is 450-500 ℃; the time of the thermal polycondensation reaction is 3-4 h.

In the above preparation method, further improvement is that in the step (2), the solvent is at least one of isopropanol, water and ethanol; the power of the ultrasonic stripping is 300-800W; the frequency of the ultrasonic stripping is 40 KHz; the ultrasonic stripping time is 8-12 h; the rotating speed of the centrifugation is 3000 rpm-4000 rpm, and the centrifugation time is 10 min-15 min.

In a further improvement of the above preparation method, in step S1, the stirring speed is 2500rpm to 3000rpm, and the stirring time is 60min to 90 min.

In the above preparation method, further improvement is that in step S2, the freeze-drying time is 24h to 28 h; the sintering is carried out in a nitrogen atmosphere; the heating rate in the sintering process is 2-5 ℃/min; the sintering temperature is 100-200 ℃; the sintering time is 3-5 h.

As a general technical concept, the invention also provides an application of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst or the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst prepared by the preparation method in treatment of antibiotic wastewater.

The application is further improved, and comprises the following steps: mixing the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets with the antibiotic wastewater, stirring, and carrying out photocatalytic degradation under the illumination condition to complete the treatment of the antibiotic wastewater.

In the application, the addition amount of the aerogel visible-light-driven photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is further improved, and 3.75 g-5.50 g of the aerogel visible-light-driven photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is added into each liter of antibiotic wastewater; the initial concentration of the antibiotics in the antibiotic wastewater is 10 mg/L-20 mg/L; the antibiotic is tetracycline hydrochloride and/or oxytetracycline hydrochloride; the stirring time is 30-60 min; the time of the photocatalytic degradation is 1-2 h.

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

(1) the invention provides an aerogel visible-light-induced photocatalyst loaded by ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets, which comprises ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets and gelatin aerogel, wherein the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets are embedded in the gelatin aerogel and loaded on the surface of the gelatin aerogel. Compared with the nitrogen-rich graphite phase carbon nitride nanosheets, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets adopted in the invention have larger specific surface area and more active sites, so that the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets have higher carrier separation efficiency and higher catalytic activity, compared with the conventional graphite phase carbon nitride nanosheets, the ultrathin nitrogen-rich graphite phase carbon nitride adopted in the invention also has a larger visible light absorption range, and meanwhile, the adopted gelatin aerogel has the advantage of large attachment area, so that the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be stably fixed in the interior and on the surface of the gelatin aerogel, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be exposed to the outside to the greatest extent, the maximum advantages of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be favorably exerted, and more importantly, the adopted gelatin has the advantages of small density, light weight, good hydrophilicity and the like, can suspend in aqueous, be favorable to realizing the effective contact of catalyst and target material, and then be favorable to realizing the effective degradation of catalyst to the target material, simultaneously, the shape of the gelatin aerogel of adoption is easily controlled, therefore also can prepare the catalyst of corresponding shape according to actual need, under the prerequisite of guaranteeing that the catalyst effectively gets rid of the target material, also be favorable to realizing the recovery and the recycle of catalyst, further reduce the secondary pollution risk that the catalyst probably caused the environment. In addition, the adopted ultrathin nitrogen-rich graphite phase carbon nitride nanosheets and the adopted gelatin aerogel do not contain toxic and harmful components, are green and environment-friendly, and do not cause secondary pollution to the environment. The ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-induced photocatalyst has the advantages of self-suspension, convenience in recovery, adjustable shape, no toxic or harmful elements, good absorption performance on visible light, excellent photocatalytic performance and the like, is a novel aerogel visible-light-induced photocatalyst with excellent performance, can be widely used for treating antibiotic wastewater, can effectively remove antibiotics in water, and has high use value and good application prospect.

(2) In the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-driven photocatalyst, the mass ratio of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet to the gelatin aerogel is optimized to be 0.5-4: 7, so that the catalyst has higher photocatalytic activity and better visible light absorption capacity, and the efficient degradation of the catalyst on a target substance is more favorably realized, because when the content of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet is too low, the relative content of catalytic components is less, the catalytic activity point is insufficient, and the catalytic capacity of the catalyst is weaker; when the content of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet is too high, too many nanosheets can generate a shielding effect, so that the light penetration capability is reduced, and the catalytic activity is reduced.

(3) The invention also provides a preparation method of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-induced photocatalyst, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet, gelatin and sodium dodecyl sulfate are used as raw materials, foaming is carried out under the stirring condition to form a precursor, and then the precursor obtained by foaming is sintered to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-induced photocatalyst. In the preparation method, the catalyst with different shapes can be prepared according to different shapes of the container, such as granular shape, block shape, round cake shape, spherical shape and the like, so that the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet loaded aerogel visible light catalyst has stronger adaptability and wider application range.

(4) The invention also provides an aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, which is used for treating the antibiotic wastewater, and the effective treatment of the antibiotic wastewater can be realized by mixing the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets with the antibiotic wastewater, stirring and carrying out photocatalytic degradation under the illumination condition, so that the effective removal of the antibiotics in the wastewater can be realized, the advantages of simple operation, low cost, high treatment efficiency, good treatment effect, good reusability and the like are realized, and the method has very important significance for effectively treating the antibiotic wastewater.

Drawings

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

Fig. 1 is a diagram of an ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) and an aerogel visible light catalyst (B) supported by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet, which are prepared in example 1 of the present invention.

Fig. 2 is an atomic force microscope image of bulk ultra-thin nitrogen-rich graphite phase carbon nitride (a) and ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets (B) made in example 1 of the present invention.

Fig. 3 is a morphological diagram of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) and the aerogel visible-light-induced photocatalyst (B) supported by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) prepared in example 1 of the present invention in water.

Fig. 4 is a graph showing a relationship between a tetracycline hydrochloride removal rate and a change with time when an aerogel visible-light-induced photocatalyst supported by ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheets is used for treating a tetracycline hydrochloride solution in embodiment 2 of the present invention.

FIG. 5 shows blocky nitrogen-rich graphite phase carbon nitride (blocky-g-C) in example 2 of the present invention₃N₅) Ultrathin nitrogen-rich graphite phase carbon nitride nanosheet (ultrathin-g-C)₃N₅) Conventional bulk graphite phase carbon nitride (bulk g-C)₃N₄) And conventional flake graphite phase carbon nitride (g-C)₃N₄Nanosheet) ultraviolet-visible diffuse reflectance absorption spectrum.

FIG. 6 is a block of nitrogen-rich graphite-phase carbon nitride (Block-g-C) in example 2 of the present invention₃N₅) Ultrathin nitrogen-rich graphite phase carbon nitride nanosheet (ultrathin-g-C)₃N₅) Conventional bulk graphite phase carbon nitride (bulk g-C)₃N₄) And conventional flake graphite phase carbon nitride (g-C)₃N₄Nanosheets) effect patterns of tetracycline hydrochloride treated under visible light.

Fig. 7 is a graph showing the relationship between the tetracycline hydrochloride removal rate and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in embodiment 3 of the present invention.

Fig. 8 is a graph showing the relationship between the tetracycline hydrochloride removal rate and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in embodiment 4 of the present invention.

Fig. 9 is a graph showing the relationship between the removal rate of oxytetracycline hydrochloride and the change with time when the oxytetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in example 4 of the present invention.

Fig. 10 is a graph of the uv-vis diffuse reflectance absorption spectra of the ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheet-supported aerogel visible light catalysts prepared in examples 1, 3, and 4 of the present invention.

Fig. 11 is a graph showing the relationship between the removal rate of tetracycline hydrochloride and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in example 5 of the present invention.

Fig. 12 is a diagram illustrating the recycling effect of the aerogel visible light catalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets in example 6 of the present invention.

Detailed Description

The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.

In the following examples, unless otherwise specified, the raw materials and equipment used were commercially available, the process used was a conventional one, the equipment used was conventional, and the data obtained were average values of three or more repeated experiments.

Example 1

An aerogel visible light catalyst loaded by ultrathin nitrogen-rich graphite phase carbon nitride nanosheets comprises the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets and gelatin aerogel, wherein the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets are embedded in the gelatin aerogel and loaded on the surface of the gelatin aerogel.

In this embodiment, the mass ratio of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet to the gelatin aerogel is 0.5: 7.

In this embodiment, the thickness of the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheet is 0.2nm to 0.4 nm.

The preparation method of the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets in the embodiment of the invention comprises the following steps:

(1) weighing 1.5g of 3-amino-1, 2, 4-triazole, placing in a 100mL crucible with a cover, placing in a muffle furnace, heating to 500 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 3h, naturally cooling to room temperature, grinding to obtain blocky nitrogen-rich graphite phase carbon nitride, and marking as blocky-g-C₃N₅。

(2) Weighing 0.2g of block-g-C in step (1)₃N₅Adding 20mL of isopropanol into a 50mL centrifuge tube, placing the centrifuge tube into an ultrasonic cleaner, ultrasonically stripping for 10h under the conditions of 300W ultrasonic power and 40KHz ultrasonic frequency, centrifuging the obtained solution for 10min under the condition that the rotating speed is 3000rpm, taking the upper layer solution, filtering and drying to obtain ultrathin nitrogen-rich graphite phase carbon nitride nanosheets marked as ultrathin-g-C₃N₅。

(3) Weighing 0.05g of ultrathin g-C in the step (2)₃N₅0.75g of gelatin and 0.0283g of sodium dodecyl sulfate are fully mixed in 10mL of deionized water, and the mixture is stirred for 60min under the condition that the rotating speed is 2500rpm, so that the precursor of the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is obtained.

(4) And (4) freeze-drying the precursor obtained in the step (3) for 24h, then placing the precursor in a nitrogen atmosphere, heating to 150 ℃ at the heating rate of 5 ℃/min, preserving the heat for 3h, and naturally cooling to room temperature to obtain the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible light catalyst.

Fig. 1 is a diagram of an ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) and an aerogel visible light catalyst (B) supported by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet, which are prepared in example 1 of the present invention. As can be seen from FIG. 1, the ultrathin g-C prepared₃N₅Is powder. Meanwhile, as can be seen from fig. 1, the aerogel visible light catalyst (B) supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is a cake-shaped material with a diameter of 6cm and a thickness of 1 cm.

Fig. 2 is an atomic force microscope image of bulk ultra-thin nitrogen-rich graphite phase carbon nitride (a) and ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets (B) made in example 1 of the present invention. As can be seen from FIG. 2, the thickness of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets (B) is 0.2nm to 0.4nm, while the thickness of the blocky ultra-thin nitrogen-rich graphite phase carbon nitride (A) is 1.5nm to 2.0 nm.

Fig. 3 is a morphological diagram of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) and the aerogel visible-light-induced photocatalyst (B) supported by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet (a) prepared in example 1 of the present invention in water. As can be seen from fig. 3, the aerogel visible-light-driven photocatalyst (B) supported by the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets is suspended in water, while the ultrathin nitrogen-rich graphite-phase carbon nitride nanosheets (a) are completely dispersed in water, so that the solution is turbid and difficult to separate solid from liquid.

Example 2

An application of an ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-induced photocatalyst in treatment of antibiotic wastewater, specifically, the preparation method comprises the following steps of:

taking two parts of the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets prepared in the example 1, respectively adding 0.375g of the aerogel visible light catalyst into tetracycline hydrochloride solution (with the volume of 100mL) with the initial concentration of 10mg/L and 20mg/L, placing the solution in the dark, stirring for 30min at the rotation speed of 100rpm to enable the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets to be fully contacted with the tetracycline hydrochloride, then placing the obtained mixed solution under a xenon lamp (300W, 420nm cutoff filter plate) at normal temperature and normal pressure, turning on a light source to carry out photocatalytic degradation, and finishing the treatment of the antibiotic wastewater.

In the photocatalytic degradation process, 4mL of the solution is sampled every 30min, the sample is directly subjected to an ultraviolet-visible spectrophotometer to measure the absorbance at 357nm, then the absorbance is converted into the concentration through the relation between the absorbance and the concentration (formula (1)), and the removal rate alpha of the tetracycline hydrochloride (formula (2)) is calculated through the concentration.

A＝0.03246×C-0.00124 (1)

In formula (1): c is the concentration of tetracycline hydrochloride (unit: mg/L); a is absorbance.

In formula (2): α is the removal (%); c₀The initial concentration of tetracycline hydrochloride in the solution before treatment (unit: mg/L); c is the tetracycline hydrochloride concentration (unit: mg/L) after the treatment.

Fig. 4 is a graph showing a relationship between a tetracycline hydrochloride removal rate and a change with time when an aerogel visible-light-induced photocatalyst supported by ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheets is used for treating a tetracycline hydrochloride solution in embodiment 2 of the present invention. As can be seen from FIG. 4, when the tetracycline hydrochloride solution is treated by the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, the tetracycline hydrochloride removal rates after 120min of visible light irradiation are 52.19% (initial concentration is 20mg/L) and 64.53% (initial concentration is 10 mg/L).

In this embodiment, the degradation effect of blocky nitrogen-rich graphite phase carbon nitride, ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, conventional blocky graphite phase carbon nitride and conventional flaky graphite phase carbon nitride on tetracycline hydrochloride is also considered, and the method includes the following steps:

0.02g of each of the block nitrogen-rich graphite-phase carbon nitrides (block-g-C) prepared in example 1 was taken₃N₅) Ultrathin nitrogen-rich graphite phase carbon nitride nanosheet (ultrathin-g-C)₃N₅) Conventional bulk graphite phase carbon nitride (bulk g-C)₃N₄) And conventional flake graphite phase carbon nitride (g-C)₃N₄Nanosheet), adding the nanosheet into 100mL of 20mg/L tetracycline hydrochloride solution, placing the prepared tetracycline hydrochloride solution in the dark, stirring for 30min at the rotation speed of 100rpm to enable the catalyst to be fully contacted with the tetracycline hydrochloride, then placing the obtained mixed solution under a xenon lamp (a 300W, 420nm cutoff filter plate) at normal temperature and normal pressure, turning on a light source to carry out photocatalytic degradation, and finishing the treatment of the antibiotic wastewater.

FIG. 5 shows blocky nitrogen-rich graphite phase carbon nitride (blocky-g-C) in example 2 of the present invention₃N₅) Ultrathin nitrogen-enriched graphitePhase carbon nitride nanosheet (ultrathin-g-C)₃N₅) Conventional bulk graphite phase carbon nitride (bulk g-C)₃N₄) And conventional flake graphite phase carbon nitride (g-C)₃N₄Nanosheet) ultraviolet-visible diffuse reflectance absorption spectrum. As is apparent from FIG. 5, nitrogen-rich graphite phase carbon nitride (bulk-g-C)₃N₅ultra-thin-g-C₃N₅) Has absorption for light below 800nm, and conventional graphite phase carbon nitride (bulk g-C)₃N₄、g-C₃N₄Nanosheets) absorb only visible light below 600 nm. The nitrogen-rich graphite phase carbon nitride absorbs more visible light.

FIG. 6 is a block of nitrogen-rich graphite-phase carbon nitride (Block-g-C) in example 2 of the present invention₃N₅) Ultrathin nitrogen-rich graphite phase carbon nitride nanosheet (ultrathin-g-C)₃N₅) Conventional bulk graphite phase carbon nitride (bulk g-C)₃N₄) And conventional flake graphite phase carbon nitride (g-C)₃N₄Nanosheets) effect patterns of tetracycline hydrochloride treated under visible light. As is evident from fig. 6, the nitrogen-rich graphite phase carbon nitride has significantly higher removal rates for tetracycline hydrochloride than the conventional graphite phase carbon nitride. The removal rate of the ultrathin nitrogen-rich graphite-phase carbon nitride to tetracycline hydrochloride is highest, the removal rate after one hour of treatment is 64.61%, while the removal rate of the conventional bulk graphite-phase carbon nitride to tetracycline hydrochloride is lowest, and the removal rate after one hour of treatment is only 22.40%, because the nitrogen-rich graphite-phase carbon nitride has better light absorption capacity than the conventional graphite-phase carbon nitride, more photon-generated carriers can be generated under the condition of illumination.

Example 3

The preparation method of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-driven photocatalyst is basically the same as that of the embodiment 1, and the difference is only that: in example 3, the amount of ultra-thin nitrogen-rich graphite phase carbon nitride nanoplatelets used was 0.10 g.

The mass ratio of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets to the gelatin aerogel in the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets-supported aerogel visible light catalyst prepared in example 3 is 1: 3.5.

0.40g of the ultra-thin nitrogen-rich graphitic carbon nitride nanosheet-supported aerogel visible light catalyst prepared in example 3 was used to treat tetracycline hydrochloride solution, with the remaining conditions being the same as in example 2.

Fig. 7 is a graph showing the relationship between the tetracycline hydrochloride removal rate and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in embodiment 3 of the present invention. As can be seen from FIG. 7, when the tetracycline hydrochloride solution is treated by the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, the tetracycline hydrochloride removal rates after 120min of visible light irradiation are 58.90% (initial concentration is 20mg/L) and 65.52% (initial concentration is 10 mg/L).

Example 4

The preparation method of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-driven photocatalyst is basically the same as that of the embodiment 1, and the difference is only that: in example 4, the amount of ultra-thin nitrogen-rich graphite phase carbon nitride nanoplatelets used was 0.20 g.

The mass ratio of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets to the gelatin aerogel in the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets-supported aerogel visible light catalyst prepared in example 4 is 2: 3.5.

0.45g of the ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheet-supported aerogel visible light catalyst prepared in example 4 was used to treat tetracycline hydrochloride solution and oxytetracycline hydrochloride solution, with the remaining conditions being the same as in example 2.

Fig. 8 is a graph showing the relationship between the tetracycline hydrochloride removal rate and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in embodiment 4 of the present invention. As can be seen from FIG. 8, when the tetracycline hydrochloride solution is treated by the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, the removal rate of tetracycline hydrochloride after irradiation for 120min under visible light is 80.78% (initial concentration is 20mg/L) and 82.29% (initial concentration is 10 mg/L).

Fig. 9 is a graph showing the relationship between the removal rate of oxytetracycline hydrochloride and the change with time when the oxytetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in example 4 of the present invention. As can be seen from FIG. 9, when the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is used for treating the oxytetracycline hydrochloride solution, the removal rate of the oxytetracycline hydrochloride after the visible-light-driven photocatalyst is irradiated for 120min is 69.37% (the initial concentration is 20mg/L) and 76.76% (the initial concentration is 10 mg/L).

Fig. 10 is a graph of the uv-vis diffuse reflectance absorption spectra of the ultra-thin nitrogen-rich graphite-phase carbon nitride nanosheet-supported aerogel visible light catalysts prepared in examples 1, 3, and 4 of the present invention. As can be seen from FIG. 10, the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets has absorption capability for light with a wavelength of 250-800 nm, and particularly has strong absorption capability for visible light with a wavelength of 400-700 nm, which indicates that the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can better absorb visible light, and is a visible light catalyst with excellent performance.

Example 5

The preparation method of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-driven photocatalyst is basically the same as that of the embodiment 1, and the difference is only that: in example 5, the amount of ultra-thin nitrogen-rich graphite phase carbon nitride nanoplatelets used was 0.30 g.

The mass ratio of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheets to the gelatin aerogel in the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet supported aerogel visible light catalyst prepared in example 5 is 3: 3.5.

0.50g of the ultra-thin nitrogen-rich graphitic carbon nitride nanosheet-supported aerogel visible light catalyst prepared in example 5 was used to treat tetracycline hydrochloride solution, with the remaining conditions being the same as in example 2.

Fig. 11 is a graph showing the relationship between the removal rate of tetracycline hydrochloride and the change with time when the tetracycline hydrochloride solution is treated by using the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible-light-induced photocatalyst in example 5 of the present invention. As can be seen from FIG. 11, when the tetracycline hydrochloride solution is treated by the aerogel visible-light-driven photocatalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, the removal rate of tetracycline hydrochloride after irradiation for 120min under visible light is 78.00% (initial concentration is 20mg/L) and 83.75% (initial concentration is 10 mg/L). The catalytic activity of the catalyst obtained in example 5 was not significantly improved compared to example 4, since when the ultra-thin nitrogen-rich graphite phase carbon nitride content was too high, a shielding effect was produced, reducing the light permeability, resulting in a reduction in catalytic activity. This can of course be done by changing the area of the catalyst to further increase the catalytic activity.

Example 6

The repeated applicability of the aerogel visible-light-driven photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets is inspected, and the method comprises the following steps:

(1) 0.45g of the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets prepared in the example 4 is added into 100mL of tetracycline hydrochloride solution with the initial concentration of 10mg/L, placed in the dark, stirred for 30min at the rotation speed of 100rpm to enable the aerogel visible light catalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets to be in full contact with tetracycline hydrochloride to achieve adsorption balance, then the obtained mixed solution is placed under a xenon lamp (300W, 420nm cutoff filter plate) at normal temperature and normal pressure, and a light source is turned on to carry out photocatalytic degradation for 120 min.

(2) And (2) after the photocatalytic degradation in the step (1) is finished, filtering, taking out the aerogel visible-light-induced photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets, cleaning the aerogel visible-light-induced photocatalyst by using ultrapure water, continuing to use the cleaned aerogel visible-light-induced photocatalyst loaded by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets for treating tetracycline hydrochloride solution, and repeating the steps (1) and (2) to carry out photocatalytic degradation on the tetracycline hydrochloride solution.

Fig. 12 is a diagram illustrating the recycling effect of the aerogel visible light catalyst supported by the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets in example 6 of the present invention. As can be seen from fig. 12, after 5 times of recycling, the removal rate of tetracycline hydrochloride by the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible light catalyst is basically unchanged, which indicates that the activity of the ultra-thin nitrogen-rich graphite phase carbon nitride nanosheet-supported aerogel visible light catalyst is not reduced.

In summary, compared with the nitrogen-rich graphite phase carbon nitride nanosheets, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets adopted in the invention have larger specific surface area and more active sites, so that the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets have higher carrier separation efficiency and higher catalytic activity, compared with the conventional graphite phase carbon nitride nanosheets, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets also have larger visible light absorption range, and meanwhile, the adopted gelatin aerogel has the advantage of large attachment area, so that the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be stably fixed in the interior and on the surface of the gelatin aerogel, the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be exposed to the outside to the greatest extent, the maximum advantages of the ultrathin nitrogen-rich graphite phase carbon nitride nanosheets can be favorably exerted, and more importantly, the adopted gelatin aerogel has the advantages of small density, light weight and high carbon dioxide content, The advantages of good hydrophilicity and the like can be suspended in water, and are favorable for realizing the effective contact of the catalyst and a target substance and further favorable for realizing the effective degradation of the catalyst on the target substance, and meanwhile, the shape of the adopted gelatin aerogel is easy to control, so that the catalyst with the corresponding shape can be prepared according to actual needs, the recovery and the reutilization of the catalyst are also favorable for realizing on the premise of ensuring that the catalyst effectively removes the target substance, and the secondary pollution risk possibly caused by the catalyst to the environment is further reduced. In addition, the adopted ultrathin nitrogen-rich graphite phase carbon nitride nanosheets and the adopted gelatin aerogel do not contain toxic and harmful components, are green and environment-friendly, and do not cause secondary pollution to the environment. The ultrathin nitrogen-rich graphite phase carbon nitride nanosheet-loaded aerogel visible-light-induced photocatalyst has the advantages of self-suspension, convenience in recovery, adjustable shape, no toxic or harmful elements, good absorption performance on visible light, excellent photocatalytic performance and the like, is a novel aerogel visible-light-induced photocatalyst with excellent performance, can be widely used for treating antibiotic wastewater, can effectively remove antibiotics in water, and has high use value and good application prospect.

The above examples are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the idea of the invention belong to the protection scope of the invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention, and such modifications and embellishments should also be considered as within the scope of the invention.