CN111320228A

Movatterモバイル変換

Info

Publication number: CN111320228A
Application number: CN202010171276.1A
Authority: CN
Inventors: 王赪胤; 李�瑞; 周小雨
Original assignee: Yangzhou University
Current assignee: Yangzhou University
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2020-06-23

Abstract

Translated fromChinese

本发明公开了一种可自清洁氮化碳凝胶及其制备方法。该凝胶由高分散的薄层氮化碳、聚合物单体y‑聚谷氨酸和交联剂三甲氧基硅烷共同制备组成，在可见光的激发下，半导体氮化碳材料产生的光生电子和空穴，与水反应生成大量的羟基自由基，半导体氮化碳材料通过单体和交联剂的聚合作用生成了氮化碳水凝胶或氮化碳气凝胶。其中，氮化碳水凝胶具有良好的形变恢复能力，在可见光的激发下氮化碳水凝胶可以对染料降解，同时具有良好的重金属离子Cr（Ⅵ）还原能力，而氮化碳气凝胶具有良好的吸水和保湿能力，在光照下可以将吸附的染料溶液进行降解，具有较好的自清洁能力。

The invention discloses a self-cleaning carbon nitride gel and a preparation method thereof. The gel is composed of a highly dispersed thin layer of carbon nitride, a polymer monomer y-polyglutamic acid and a cross-linking agent trimethoxysilane. Under the excitation of visible light, the photogenerated electrons generated by the semiconductor carbon nitride material and holes, react with water to generate a large number of hydroxyl radicals, and the semiconductor carbon nitride material generates carbon nitride hydrogel or carbon nitride aerogel through the polymerization of monomer and crosslinking agent. Among them, carbon nitride hydrogel has good deformation recovery ability, carbon nitride hydrogel can degrade dyes under the excitation of visible light, and has good reduction ability of heavy metal ion Cr(VI), while carbon nitride aerogel has Good water absorption and moisturizing ability, can degrade the adsorbed dye solution under light, and has good self-cleaning ability.

Description

Translated fromChinese

一种可自清洁氮化碳凝胶及其制备方法A kind of self-cleaning carbon nitride gel and preparation method thereof

技术领域technical field

本发明涉及一种氮化碳水凝胶和氮化碳气凝胶材料及其制备方法和应用，属于纳米材料应用领域。The invention relates to a carbon nitride hydrogel and a carbon nitride aerogel material, a preparation method and application thereof, and belongs to the application field of nanomaterials.

背景技术Background technique

环境污染一直是影响人类生存环境的主要因素，其中，染料污染、重金属污染的处理方式主要有吸附法、萃取法、膜分离法、混凝沉降法、催化氧化法、电化学法、生物法。然而这些方法多数会引起二次污染，所以采取有良好的生物相容性的处理方法是亟需解决的问题。近年来兴起的光催化技术在环境治理中有很大的潜能。石墨相氮化碳（g-C₃N₄）作为一种新型聚合物半导体材料，可以吸收可见光，有较好的稳定性，它被公认为是一种具有发展潜力的环境友好的新型光催化半导体材料。现有的技术中利用g-C₃N₄粉末直接进行染料降解存在一定的效果，但是对g-C₃N₄后处理以及循环利用没有很好地解决方案。Environmental pollution has always been the main factor affecting human living environment. Among them, dye pollution and heavy metal pollution are mainly treated by adsorption method, extraction method, membrane separation method, coagulation sedimentation method, catalytic oxidation method, electrochemical method and biological method. However, most of these methods will cause secondary pollution, so it is an urgent problem to adopt a treatment method with good biocompatibility. The photocatalytic technology emerging in recent years has great potential in environmental governance. Graphitic carbon nitride (gC₃ N₄ ), as a new type of polymer semiconductor material, can absorb visible light and has good stability. It is recognized as an environmentally friendly new photocatalytic semiconductor material with development potential. . In the prior art, the use of gC₃ N₄ powder to directly degrade dyes has certain effects, but there is no good solution for the post-treatment and recycling of gC₃ N₄ .

发明内容SUMMARY OF THE INVENTION

本发明的目的在于提供一种氮化碳凝胶材料及其制备方法。The purpose of the present invention is to provide a carbon nitride gel material and a preparation method thereof.

实现本发明目的的技术解决方案为：一种可自清洁氮化碳凝胶，采用以下步骤制备：The technical solution for realizing the object of the present invention is: a self-cleaning carbon nitride gel, prepared by adopting the following steps:

第一步，将氮化碳均匀地分散在水溶液中；In the first step, the carbon nitride is uniformly dispersed in the aqueous solution;

第二步，将聚合物单体均匀地分散在水溶液中；In the second step, the polymer monomers are uniformly dispersed in the aqueous solution;

第三步，将第一步所得氮化碳水溶液滴加到第二步所得聚合物单体水溶液中；In the third step, the carbon nitride aqueous solution obtained in the first step is added dropwise to the polymer monomer aqueous solution obtained in the second step;

第四步，向第三步所得混合溶液中滴加交联剂，并搅拌分散均匀；In the fourth step, the cross-linking agent is added dropwise to the mixed solution obtained in the third step, and the mixture is stirred and dispersed evenly;

第五步，将分散均匀的溶液移入模具，干燥。The fifth step is to move the evenly dispersed solution into the mold and dry it.

较佳的，第一步中，氮化碳通过煅烧富氮前驱体所得，其具体制备步骤是：将尿素装入带盖的坩埚中，将其置于管式炉中程序升温至500-550℃并保温2-4h，所得固体粉末即为氮化碳。Preferably, in the first step, carbon nitride is obtained by calcining a nitrogen-rich precursor, and the specific preparation steps are: put urea into a crucible with a lid, and place it in a tube furnace to program the temperature to 500-550 ℃. ℃ and heat preservation for 2-4h, the obtained solid powder is carbon nitride.

较佳的，第二步中，聚合物单体为γ-聚谷氨酸。Preferably, in the second step, the polymer monomer is γ-polyglutamic acid.

较佳的，第三步中，氮化碳和聚合物单体的质量比为1:10-1:40。Preferably, in the third step, the mass ratio of carbon nitride and polymer monomer is 1:10-1:40.

较佳的，第四步中，交联剂为三甲基硅烷，聚合物单体和交联剂的质量比为1:1-4:1。Preferably, in the fourth step, the cross-linking agent is trimethylsilane, and the mass ratio of the polymer monomer and the cross-linking agent is 1:1-4:1.

较佳的，第五步中，所述的干燥是指置于35-40℃下烘干，或冷冻干燥。Preferably, in the fifth step, the drying refers to drying at 35-40° C., or freeze-drying.

本发明与现有技术相比，其优点在于：（1）以尿素为前驱体煅烧所得的氮化碳质地较轻，带隙能合适展现出更好的光催化性能，并且该方法制得的氮化碳易于分散在水溶液中；（2）制备氮化碳凝胶所用的原料y-聚谷氨酸、氮化碳都有很好的生物相容性，对环境，人体都无害，有希望应用在仿生材料的研究。（3）制备的氮化碳气凝胶密度小，质地轻，有很好的吸水性和自清洁能力。（4）利用氮化碳凝胶进行染料降解和重金属还原存在后处理方便的优势。Compared with the prior art, the present invention has the following advantages: (1) the carbon nitride obtained by calcining urea as a precursor is lighter in texture, and has a suitable band gap to exhibit better photocatalytic performance, and the carbon nitride obtained by the method Carbon nitride is easy to disperse in aqueous solution; (2) The raw materials y-polyglutamic acid and carbon nitride used in the preparation of carbon nitride gel have good biocompatibility, and are harmless to the environment and human body. Hope to apply it in the research of biomimetic materials. (3) The prepared carbon nitride aerogel has low density, light texture, good water absorption and self-cleaning ability. (4) The use of carbon nitride gel for dye degradation and heavy metal reduction has the advantage of convenient post-processing.

附图说明Description of drawings

图1为实施例1所制备的氮化碳水凝胶的数码照片。Figure 1 is a digital photograph of the carbon nitride hydrogel prepared in Example 1.

图2为实施例1所制备的氮化碳水凝胶的扫描电镜图。2 is a scanning electron microscope image of the carbon nitride hydrogel prepared in Example 1.

图3为实施例2所制备的氮化碳气凝胶的扫描电镜图。3 is a scanning electron microscope image of the carbon nitride aerogel prepared in Example 2.

图4为石墨相氮化碳粉末和实施例2所制备的氮化碳气凝胶的X射线衍射图谱。4 is the X-ray diffraction pattern of the graphite phase carbon nitride powder and the carbon nitride aerogel prepared in Example 2.

图5为石墨相氮化碳粉末、实施例1所制备的氮化碳水凝胶、实施例2所制备的氮化碳气凝胶的傅里叶红外光谱图。FIG. 5 is the Fourier transform infrared spectrogram of graphitic carbon nitride powder, carbon nitride hydrogel prepared in Example 1, and carbon nitride aerogel prepared in Example 2.

图6为实施例3所制备的氮化碳水凝胶还原六价铬离子的效果图。6 is a graph showing the effect of reducing hexavalent chromium ions by carbon nitride hydrogel prepared in Example 3.

图7为实施例4所制备的氮化碳气凝胶降解罗丹明B染料溶液的效果图。7 is an effect diagram of the carbon nitride aerogel prepared in Example 4 for degrading the rhodamine B dye solution.

图8为实施例4所制备的氮化碳气凝胶降解罗丹明B染料溶液的过程图。8 is a process diagram of the carbon nitride aerogel prepared in Example 4 for degrading the rhodamine B dye solution.

具体实施方式Detailed ways

本发明制备的氮化碳水凝胶和氮化碳气凝胶，都对染料污染物有突出的降解作用，对重金属Cr（Ⅵ）有明显的还原作用，并且氮化碳凝胶有自清洁功能。The carbon nitride hydrogel and carbon nitride aerogel prepared by the invention have outstanding degradation effect on dye pollutants, obvious reduction effect on heavy metal Cr(VI), and carbon nitride gel has self-cleaning function .

本发明的氮化碳水凝胶、氮化碳气凝胶采用以下步骤制备而得：The carbon nitride hydrogel and carbon nitride aerogel of the present invention are prepared by the following steps:

第一步，将单体（γ-聚谷氨酸，0.5-2g）均匀地分散在水溶液中；In the first step, the monomer (γ-polyglutamic acid, 0.5-2g) is uniformly dispersed in the aqueous solution;

第二步，将石墨相氮化碳粉末（0.05-0.1g）均匀地分散在水溶液中；In the second step, the graphite phase carbon nitride powder (0.05-0.1g) is uniformly dispersed in the aqueous solution;

第三步，将分散均匀的氮化碳水溶液滴加到分散均匀的单体溶液中；The third step is to drop the uniformly dispersed carbon nitride aqueous solution into the uniformly dispersed monomer solution;

第四步，向第三步的混合溶液中滴加交联剂（三甲氧基硅烷，0.5-1g），并搅拌分散均匀；In the fourth step, dropwise add the crosslinking agent (trimethoxysilane, 0.5-1 g) to the mixed solution in the third step, and stir and disperse evenly;

第五步，将分散均匀的溶液移入模具，烘干。In the fifth step, the uniformly dispersed solution is moved into the mold and dried.

实施例1：Example 1:

第一步，将0.5g γ-聚谷氨酸均匀地分散在10mL水中，搅拌1h；In the first step, 0.5 g of γ-polyglutamic acid was evenly dispersed in 10 mL of water, and stirred for 1 h;

第二步，将0.05g氮化碳均匀地分散在10mL水中，搅拌2h；In the second step, 0.05g of carbon nitride was evenly dispersed in 10mL of water, and stirred for 2h;

第三步，将分散均匀的氮化碳水溶液滴加到分散均匀的γ-聚谷氨酸水溶液中；The third step is to drop the uniformly dispersed carbon nitride aqueous solution into the uniformly dispersed γ-polyglutamic acid aqueous solution;

第四步，向第三步的混合溶液中滴加1g三甲氧基硅烷，并搅拌3h；In the fourth step, 1 g of trimethoxysilane was added dropwise to the mixed solution in the third step, and stirred for 3h;

第五步，将分散均匀的溶液移入模具，真空烘箱38℃烘干12h得氮化碳水凝胶。In the fifth step, the uniformly dispersed solution was moved into the mold, and dried in a vacuum oven at 38° C. for 12 hours to obtain carbon nitride hydrogel.

第六步，对所制备的氮化碳水凝胶进行表征，图1为氮化碳水凝胶的数码照片，图2为氮化碳水凝胶的扫描电镜图，图5为氮化碳水凝胶的傅里叶红外光谱图。The sixth step is to characterize the prepared carbon nitride hydrogel. Figure 1 is a digital photo of the carbon nitride hydrogel, Figure 2 is a scanning electron microscope image of the carbon nitride hydrogel, and Figure 5 is the carbon nitride hydrogel. Fourier transform infrared spectrogram.

实施例2：Example 2:

第五步，将分散均匀的溶液移入模具，冷冻干燥脱水得氮化碳气凝胶。In the fifth step, the uniformly dispersed solution is moved into the mold, and the carbon nitride aerogel is obtained by freeze-drying and dehydration.

第六步，对所制备的氮化碳气凝胶进行表征，图3为氮化碳气凝胶的扫描电镜图，图4为氮化碳气凝胶的X射线衍射图谱，图5为氮化碳气凝胶的傅里叶红外光谱图。The sixth step is to characterize the prepared carbon nitride aerogel. Figure 3 is the scanning electron microscope image of the carbon nitride aerogel, Figure 4 is the X-ray diffraction pattern of the carbon nitride aerogel, and Figure 5 is the nitrogen Fourier transform infrared spectra of carbonized aerogels.

实施例3：Example 3:

第五步，将分散均匀的溶液移入模具，真空烘箱38℃烘干12h得氮化碳水凝胶。；In the fifth step, the uniformly dispersed solution was moved into the mold, and dried in a vacuum oven at 38° C. for 12 hours to obtain carbon nitride hydrogel. ;

第六步，将制得的氮化碳水凝胶置于装有50mL50ppmCr（Ⅵ）溶液的烧杯中，将氙灯光源置于烧杯上方25cm处进行光催化还原重金属离子实验。每隔20min取1mL溶液用于紫外分光光度计的测量，所测得的结果即为溶液中Cr（Ⅵ）的浓度。In the sixth step, the prepared carbon nitride hydrogel was placed in a beaker containing 50 mL of 50 ppm Cr(VI) solution, and the xenon lamp light source was placed 25 cm above the beaker to carry out the photocatalytic reduction experiment of heavy metal ions. Take 1mL of solution every 20min for measurement by UV spectrophotometer, and the measured result is the concentration of Cr(VI) in the solution.

实施例3所制备的氮化碳水凝胶还原六价铬离子的效果如图6所示。紫外分光光度计测量的结果表明，在80min内，0.5g氮化碳水凝胶可将50mL 50ppm的Cr（Ⅵ）溶液中的Cr（Ⅵ）离子完全还原。The effect of reducing hexavalent chromium ions by the carbon nitride hydrogel prepared in Example 3 is shown in FIG. 6 . The results of UV spectrophotometer measurements showed that within 80 min, 0.5 g of carbon nitride hydrogel could completely reduce Cr(VI) ions in 50 mL of 50 ppm Cr(VI) solution.

实施例4：Example 4:

第三步，将分散均匀的氮化碳水溶液滴加到分散均匀的y-聚谷氨酸水溶液中；In the third step, the uniformly dispersed carbon nitride aqueous solution is added dropwise to the uniformly dispersed y-polyglutamic acid aqueous solution;

第五步，将分散均匀的溶液移入模具，冷冻干燥脱水得氮化碳气凝胶；The fifth step, the uniformly dispersed solution is moved into the mold, freeze-drying and dehydration to obtain carbon nitride aerogel;

第六步，将制得的氮化碳气凝胶置于装有50mL50ppm罗丹明B溶液的烧杯中，将氙灯光源置于烧杯上方25cm处进行光催化降解染料实验；In the sixth step, the prepared carbon nitride aerogel was placed in a beaker containing 50 mL of 50 ppm Rhodamine B solution, and the xenon lamp light source was placed 25 cm above the beaker to perform a photocatalytic degradation dye experiment;

第七步，静置半小时后，氮化碳气凝胶将50mL50ppm的罗丹明B溶液全部吸附，并在外光上表现出罗丹明B染料的颜色，表明只是单纯地吸附了染料溶液；The seventh step, after standing for half an hour, the carbon nitride aerogel adsorbed all the 50mL 50ppm Rhodamine B solution, and showed the color of Rhodamine B dye on the external light, indicating that the dye solution was simply adsorbed;

第八步，打开氙灯光源后，进行20min的光催化降解后，氮化碳气凝胶的颜色完全褪去，表明成功地降解了罗丹明B染料。In the eighth step, after turning on the xenon lamp light source and carrying out photocatalytic degradation for 20 minutes, the color of the carbon nitride aerogel completely faded, indicating that the rhodamine B dye was successfully degraded.

第九步，通过物理挤压的方式将降解后气凝胶中的水溶液进行紫外分光光度法检测，对比降解前后的测试结果成功验证了氮化碳气凝胶对罗丹明B染料的降解。In the ninth step, the aqueous solution in the degraded aerogel is detected by ultraviolet spectrophotometry by means of physical extrusion, and the degradation of rhodamine B dye by carbon nitride aerogel is successfully verified by comparing the test results before and after the degradation.

实施例4所制备的氮化碳气凝胶降解罗丹明B染料溶液的效果如图7所示。紫外分光光度计测量的结果表明，在经过20min的光催化降解后，氮化碳气凝胶对50mL50ppm的罗丹明B溶液降解效果显著，从而说明了所制备的氮化碳气凝胶有很好的自清洁能力。The effect of the carbon nitride aerogel prepared in Example 4 for degrading the rhodamine B dye solution is shown in FIG. 7 . The results of UV spectrophotometer measurement showed that after 20min of photocatalytic degradation, the carbon nitride aerogel had a significant degradation effect on 50mL50ppm Rhodamine B solution, which indicated that the prepared carbon nitride aerogel had good performance. self-cleaning ability.

图8为实施例4所制备的氮化碳气凝胶降解罗丹明B染料溶液的过程图。a是将氮化碳气凝胶置于罗丹明B染料溶液进行吸附；b表明经过30min的吸附，50mL的罗丹明B染料溶液完全被氮化碳气凝胶吸附，这也表明了制备的氮化碳气凝胶有很好的吸水性；c是通过氙灯进行光催化降解的装置示意图；d是经过光催化降解后的凝胶的数码照片。8 is a process diagram of the carbon nitride aerogel prepared in Example 4 for degrading the rhodamine B dye solution. a is carbon nitride aerogel placed in rhodamine B dye solution for adsorption; b shows that after 30min of adsorption, 50 mL of rhodamine B dye solution is completely adsorbed by carbon nitride aerogel, which also shows that the prepared nitrogen Carbonized aerogel has good water absorption; c is the schematic diagram of the device for photocatalytic degradation by xenon lamp; d is the digital photo of the gel after photocatalytic degradation.

Claims

1. A preparation method of self-cleaning carbon nitride gel is characterized by comprising the following steps:

the first step, carbon nitride is uniformly dispersed in an aqueous solution;

a second step of uniformly dispersing the polymer monomer in an aqueous solution;

thirdly, dripping the carbon nitride aqueous solution obtained in the first step into the polymer monomer aqueous solution obtained in the second step;

step four, dripping a cross-linking agent into the mixed solution obtained in the step three, and stirring and dispersing uniformly;

and fifthly, transferring the uniformly dispersed solution into a mold and drying.

2. The method of claim 1, wherein in the first step the carbon nitride is obtained by calcining a nitrogen-rich precursor, and is prepared by: and (3) putting the urea into a crucible with a cover, placing the crucible in a tube furnace, raising the temperature to 500-550 ℃ by a program, and preserving the heat for 2-4h to obtain solid powder, namely the carbon nitride.

3. The method of claim 1, wherein in the second step, the polymer monomer is gamma-polyglutamic acid.

4. The method according to claim 1, wherein in the third step, the mass ratio of the carbon nitride to the polymer monomer is 1:10 to 1: 40.

5. The method of claim 1, wherein in the fourth step, the crosslinking agent is trimethylsilane and the mass ratio of the polymer monomer to the crosslinking agent is from 1:1 to 4: 1.

6. The method of claim 1, wherein in the fifth step, the drying is drying at 35-40 ℃.

7. The method of claim 1, wherein said drying is freeze drying.

8. A self-cleanable carbon nitride gel prepared by the method of any one of claims 1-7.