Stripped body phase g-C3N4Preparation method and application of
阅读说明：本技术 一种剥离体相g-C3N4的制备方法及应用 (Stripped body phase g-C3N4Preparation method and application of ) 是由 李雪 陶涛 黄宝磊 孙昊 于 2021-01-20 设计创作，主要内容包括：本发明提供一种剥离体相g-C-3N-4的制备方法及应用,该方法包括以下步骤,(1)将金属钠缓慢加入醇中持续搅拌2 h,待金属钠反应完全得醇钠溶液；(2)缓慢加入体相g-C-3N-4,加热搅拌进行剥离,抽滤洗涤至中性后干燥即可。该发明降低了剥离后的废液对设备及环境的危害,经过该方法获得的剥离后氮化碳材料,可以作为催化剂在光催化和废水处理中的应用,在可见光条件下降解罗丹明B和亚甲基蓝的效率相比体相氮化碳分别提升了19.5%和17.98%,具有很好的应用效果。(The present invention provides a exfoliated phase g-C 3 N 4 The preparation method comprises the following steps of (1) slowly adding metal sodium into alcohol, and continuously stirring for 2 hours until the metal sodium completely reacts to obtain a sodium alkoxide solution; (2) slowly adding into bulk phase g ‑C 3 N 4 Heating and stirring for stripping, filtering and washing to be neutral, and drying. The invention reduces the harm of the stripped waste liquid to equipment and environment, and the stripped carbon nitride material obtained by the method can be used as a catalyst in photocatalysis and wastewater treatment, and can be applied to photocatalysis and wastewater treatmentThe efficiency of dissolving rhodamine B and methylene blue under the condition of visible light is respectively improved by 19.5 percent and 17.98 percent compared with bulk-phase carbon nitride, and the method has good application effect.)
1. A method for stripping carbon nitride is characterized in that: comprises the following steps of (a) carrying out,
(1) slowly adding metal sodium into alcohol, and continuously stirring for 2 h until the metal sodium completely reacts to obtain a sodium alkoxide solution;
(2) slowly adding into bulk phaseg-C3N4And (4) obtaining stripping liquid, heating and stirring for stripping, performing suction filtration and washing to be neutral, and drying.
2. The method for stripping carbon nitride according to claim 1, wherein in step (1), the alcohol comprises one or more of methanol, ethanol and tert-butyl alcohol.
3. The method for stripping carbon nitride according to claim 1 or 2, characterized in that: said bulk phaseg-C3N4The mass ratio of the sodium metal to the sodium metal is 1 (1-2).
4. The method for stripping carbon nitride according to claim 1, wherein: in the step (2), the mixture is heated and stirred at the temperature of 40-80 ℃ for 6-12 hours.
5. The method for stripping carbon nitride according to claim 1, wherein: in the step (2), the drying is carried out for 12 hours at the temperature of 60 ℃.
6. The method of claim 1, wherein: in the step (2), the concentration of the stripping solution is 3-10 g/L.
7. A stripped carbon nitride material obtained by the method according to any one of claims 1 to 6.
8. Use of the exfoliated carbon nitride material of claim 7 as a catalyst in photocatalysis and wastewater treatment.
9. Use according to claim 8, characterized in that: the wastewater is organic dye wastewater.
Technical Field
The invention belongs to the technical field of carbon nitride materials, and particularly relates to a stripper phaseg-C3N4The preparation method and the application thereof.
Background
Two-dimensional (2D) graphitic carbon nitride since its discovery by scientists in 1834g-C3N4) Photocatalytic material for H as a promising organic semiconductor2Production, pollutant treatment and CO2Reduction, due to its unique optical and electronic properties, is very important in photocatalytic, non-toxic and convenient synthetic routes, and has attracted great attention. The carbon nitride material has a structure similar to that of graphene and is formed by stacking two-dimensional carbon and nitrogen atomic layers. Bulk phase prepared by simple high temperature thermal polymerizationg-C3N4The defects of compact accumulation, small specific surface area, narrow response range to visible light, quick recombination of photo-generated electron-hole pairs and the like exist, and the large-scale popularization and application of the photo-generated electron-hole pairs are limited. Therefore, inspired by hummers method for preparing graphene oxide, the method of stripping carbon nitride by adopting concentrated sulfuric acid is applied to preparationg-C3N4A nanosheet of (a). However, concentrated sulfuric acid has strong oxidizing property and corrosivity, the requirement on experimental operation is high, and the stripping waste liquid has great harm to the environment. Therefore, the invention explores a new method for stripping the carbon nitride material by sodium ethoxide, provides a new scheme for solving the problems of low visible light utilization rate, difficult stripping, environment friendliness and the like of the carbon nitride material, verifies that the method does not damage the structure of the carbon nitride, and explores the removal effect of the carbon nitride material on soluble organic dye before and after stripping under the visible light condition.
Disclosure of Invention
In order to solve the problems of low visible light utilization rate, difficult stripping, small specific surface area and the like of the carbon nitride material, the carbon nitride material is enhanced in H2Production, pollutant treatment and CO2The invention provides a novel method for stripping a carbon nitride material by sodium ethoxide, and the carbon nitride material treated by the method can effectively enhance the degradation effect on organic dyes such as methylene blue and rhodamine B under the condition of visible light.
In order to solve the technical problems, the invention provides one of the following technical schemesThe method for stripping the carbon nitride comprises the following steps of (1) slowly adding metal sodium into alcohol, and continuously stirring for 2 hours until the metal sodium completely reacts to obtain a sodium alkoxide solution; (2) slowly adding into bulk phaseg-C3N4And (4) obtaining stripping liquid, heating and stirring for stripping, performing suction filtration and washing to be neutral, and drying.
Preferably, in step (1), the alcohol includes one or more of methanol, ethanol and tert-butanol.
Preferably, the bulk phaseg-C3N4The mass ratio of the sodium metal to the sodium metal is 1 (1-2).
Preferably, in the step (2), the heating and stirring are carried out at the temperature of 40-80 ℃ for 6-12 hours.
Preferably, in the step (2), the drying is performed at 60 ℃ for 12 h.
Preferably, in the step (2), the concentration of the stripping solution is 3-10 g/L.
As another aspect of the invention, the invention provides a post-spalling carbon nitride material.
As another aspect of the invention, the invention provides the use of the exfoliated carbon nitride material as a catalyst in photocatalysis and wastewater treatment.
Preferably, the wastewater is organic dye wastewater.
The invention has the beneficial effects that:
the reagent required by the invention has low danger and simple operation process, and does not need complex and expensive equipment. The invention reduces the harm of the stripped waste liquid to equipment and environment; the preparation method provided by the invention is determined by characterization means such as XRD, infrared spectrogram and SEM that the structure of the carbon nitride material is not damaged, and the efficiency of the prepared stripped carbon nitride material as a photocatalyst for degrading rhodamine B and methylene blue is improved by 19.5% and 17.98% respectively compared with bulk-phase carbon nitride.
Drawings
FIG. 1 is an XRD pattern of the carbon nitride material before and after exfoliation of sodium ethoxide prepared in example 2;
FIG. 2SEM images of carbon nitride material before and after sodium ethoxide exfoliation prepared for example 2, wherein a and b areg-C3N4SEM pictures of different specifications before stripping, c and d are sodium ethoxide strippingg-C3N4SEM pictures under different specifications;
FIG. 3 is a Fourier infrared spectrum of the carbon nitride material before and after sodium ethoxide exfoliation prepared in example 2;
FIG. 4 is a graph showing the effect of carbon nitride materials on rhodamine B degradation before and after sodium ethoxide exfoliation, prepared in example 2, wherein the front and back correspond to the left and right, respectively;
FIG. 5 is a graph showing the degradation effect of the carbon nitride material on methylene blue before and after stripping sodium ethoxide prepared in example 2, wherein the front and the back correspond to the left and the right, respectively;
FIG. 6 is a schematic structural diagram of the sodium ethoxide exfoliated carbon nitride material prepared by the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Bulk phase for use in the inventiong-C3N4The material is prepared by the following steps:
taking melamine as a raw material, heating to 400 ℃ at a speed of 10 ℃/min in a muffle furnace, and keeping the temperature for 1 h; then continuously heating to 550 ℃, preserving heat for 2 hours, cooling to room temperature, taking out and grinding to obtain the product.
Example 1
A novel method for stripping carbon nitride is characterized by comprising the following steps:
(1) adding 150 ml of methanol into a 250 ml three-neck flask, weighing 1 g of metal sodium, slowly adding the metal sodium into a methanol solution, continuously stirring for 6 hours, generating bubbles at the moment, and obtaining a sodium methoxide solution after the metal sodium completely reacts;
(2) weighing 1 g of bulk phaseg-C3N4The material is slowly added into the mixed solution in the sodium methoxide solution in the step (1), and then the mixed solution is put into an oil bath kettle at the temperature of 70 ℃ to be heated, refluxed, stirred and stripped for 12 hours.
(3) And (3) filtering and washing the reaction mixed liquor obtained in the step (2) to be neutral, then placing the solid material in an oven for drying at 60 ℃ for 12 h, grinding and bottling to obtain the sodium methoxide stripping carbon nitride.
Example 2
A novel method for stripping carbon nitride is characterized by comprising the following steps:
(1) adding 150 ml of absolute ethyl alcohol into a 250 ml three-neck flask, weighing 1 g of metal sodium, slowly adding the metal sodium into the absolute ethyl alcohol, continuously stirring for 6 hours, generating bubbles at the moment, and obtaining a sodium ethoxide solution after the metal sodium completely reacts;
(2) weighing 1 g of bulk phaseg-C3N4The materials are slowly added into the mixed solution of the sodium ethoxide solution in the step (1), the solution gradually becomes light yellow silky milk, and then the mixture is put into an oil bath kettle at the temperature of 70 ℃ to be heated, refluxed, stirred and stripped for 12 hours.
(3) And (3) filtering and washing the reaction mixed liquor obtained in the step (2) to be neutral, then placing the solid material in an oven for drying at 60 ℃ for 12 h, grinding and bottling to obtain the sodium ethoxide-stripped carbon nitride.
The effect of the stripping method was analyzed as the results of example 2. From the XRD diffractogram of fig. 1, it can be seen that the carbon nitride before and after exfoliation has a similar diffraction peak at 27.3 °, indicating that the crystal structures before and after exfoliation are the same, corresponding to the (002) crystal plane of the carbon nitride, indicating that the exfoliation method does not change the crystal structure of the carbon nitride; in FIG. 2, a and b are scanning electron microscope images of 500 nm and 5 nm of bulk carbon nitride, respectively, and it can be seen that the bulk structure of the bulk carbon nitride material is more obvious and is similar to a stone shape; and c and d are scanning electron microscope images of 500 nm and 5 nm of carbon nitride stripped by sodium ethoxide, compared with a and b, the blocky structures in the c and d images are obviously reduced, and the stripped carbon nitride in the d image is found to show a loose and multi-fold structure similar to lamellar rock for the 5 nm image, which indicates that the stripping method effectively improves the appearance and lamellar structure of bulk phase carbon nitride. FIG. 3 is a Fourier infrared spectrum of 810 cm-1Is a characteristic absorption peak corresponding to bending vibration of the triazine ring, 890 cm-1Is the vibration signal of the N-H bond, and is at 1100-1700 cm-1The absorption wave band shows that the C-N heterocyclic ring stretches and contracts and vibrates to absorb [ C-N (-C) -C or C-NH-C]3000 + 3700 cm-1Residual N-H in the non-condensed amino group and vibrational signals from the adsorption of-OH bonds in water molecules. In addition, the characteristic absorption peak of the carbon nitride after the sodium ethoxide stripping is sharper, which indicates that the crystal crystallinity of the stripped polymer after the sodium ethoxide is better; FIG. 4 is a diagram of the degradation effect of a carbon nitride material on rhodamine B before and after sodium ethoxide stripping, wherein the left and right diagrams are respectively the effect of bulk-phase carbon nitride and the effect of carbon nitride after sodium ethoxide stripping on rhodamine B, so that the effect of carbon nitride after stripping on rhodamine B is better, the time for dye solution decoloration is faster, and the stripping method is proved to improve the photocatalytic activity of the carbon nitride material; in fig. 5, the left and right images are respectively the effect images of the carbon nitride after stripping the bulk phase carbon nitride and sodium ethoxide to degrade methylene blue, and it is obvious that the carbon nitride material after stripping has better degradation and decoloration effects. Therefore, the characterization tests and experiments show that the stripping method can effectively improve the photocatalytic performance of the carbon nitride material.
Example 3
A novel method for stripping carbon nitride is characterized by comprising the following steps:
(1) adding 150 ml of tert-butyl alcohol into a 250 ml three-neck flask, weighing 1 g of metal sodium, slowly adding the metal sodium into absolute ethyl alcohol, continuously stirring for 6 hours, generating bubbles at the moment, and obtaining a sodium tert-butyl alcohol solution after the metal sodium completely reacts;
(2) weighing 1 g of bulk phaseg-C3N4Slowly adding the materials into the sodium tert-butoxide solution obtained in the step (1) to obtain a mixed solution, and continuously stirring and stripping the mixed solution at 70 ℃ for 12 h.
(3) And (3) filtering and washing the reaction mixed liquor obtained in the step (2) to be neutral, then placing the solid material in an oven for drying at 60 ℃ for 12 h, grinding and bottling to obtain the sodium tert-butoxide stripped carbon nitride.
The sodium ethoxide stripping carbon nitride material prepared by the invention has a structure shown as a formula I in figure 6. The stripping method employed in the present invention is not changedg-C3N4But enhances its degradation properties.The invention also provides application of the carbon nitride material stripped by the sodium ethoxide to photocatalytic degradation of organic dyes rhodamine B and methylene blue, wherein the dye concentration is controlled at 10 ppm, 50 mg of the carbon nitride material before and after stripping is weighed, 50 ml of organic dye wastewater is added, after the material and the solution are uniformly dispersed by ultrasonic treatment for 10min, a dark reaction is carried out for 1h to achieve the adsorption and desorption balance of the catalyst on the dye solution, a lamp is turned on for degradation of the dye under visible light, 4 ml of the solution is extracted at intervals, the solution is centrifuged, and the supernatant is taken to determine the ultraviolet-visible absorption spectrum. The results are shown in FIGS. 3-5.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.