阅读说明：本技术 一种硫化镉@水热碳复合光催化材料的制备及其在降解亚甲基蓝中的应用 (Preparation method of cadmium sulfide @ hydrothermal carbon composite photocatalytic material and application of composite photocatalytic material in methylene blue degradation ) 是由 马纪亮 孙润仓 张俊强 于 2020-08-14 设计创作，主要内容包括：本发明公开了一种硫化镉@水热碳复合光催化材料的制备及其在降解亚甲基蓝中的应用,属于光催化领域。所述复合光催化材料的制备方法为：将乙酸镉和硫脲加入水中,加入聚丙烯酸和氨水,搅拌均匀,高温加热反应,离心、干燥得到硫化镉量子点。将硫化镉量子点加至乙酸溶液中,再加入壳聚糖,搅拌充分后超声脱泡,利用碱性溶液进行碱浴处理,将其在高温烘箱中反应,获得硫化镉@水热碳复合光催化材料。本发明合成的复合光催化材料具有稳定性好、催化活性高、见效快、能耗低、可重复使用等优点,该工艺过程中加入硫化镉通过化学交联得到的具有三维立体结构的复合材料,其使用过程具有见效快、能耗低、降解效果好、易于实现工业化生产等特点。(The invention discloses a preparation method of a cadmium sulfide @ hydrothermal carbon composite photocatalytic material and application of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material in degradation of methylene blue, and belongs to the field of photocatalysis. The preparation method of the composite photocatalytic material comprises the following steps: adding cadmium acetate and thiourea into water, adding polyacrylic acid and ammonia water, uniformly stirring, heating at high temperature for reaction, centrifuging, and drying to obtain the cadmium sulfide quantum dot. Adding cadmium sulfide quantum dots into an acetic acid solution, adding chitosan, stirring fully, performing ultrasonic defoaming, performing alkali bath treatment by using an alkaline solution, and reacting in a high-temperature oven to obtain the cadmium sulfide @ hydrothermal carbon composite photocatalytic material. The composite photocatalytic material synthesized by the method has the advantages of good stability, high catalytic activity, quick effect, low energy consumption, reusability and the like, and the composite material with the three-dimensional structure is obtained by adding cadmium sulfide in the process and performing chemical crosslinking, and has the characteristics of quick effect, low energy consumption, good degradation effect, easiness in realizing industrial production and the like in the using process.)

1. A preparation method of a cadmium sulfide @ hydrothermal carbon composite photocatalytic material is characterized by comprising the following steps:

(1) adding cadmium acetate and thiourea into water, uniformly stirring, adding polyacrylic acid and ammonia water, uniformly stirring, heating and reacting for 5-6 hours at the temperature of 150-200 ℃, centrifuging and drying a reaction product to obtain cadmium sulfide quantum dots;

wherein the ratio of the cadmium acetate to the thiourea to the water to the polyacrylic acid to the ammonia water is 0.5-5 mmol: 0.5-5 mmol: 40-100 mL: 50-500 uL: 50-500 uL;

(2) dispersing the cadmium sulfide quantum dots obtained in the step (1) in an acetic acid solution, adding chitosan, stirring until the chitosan is completely dissolved, and then performing ultrasonic defoaming;

wherein the concentration of the acetic acid solution is 1-10%; the ratio of the cadmium sulfide quantum dots to the chitosan to the acetic acid solution is 0.001-0.05 g: 0.1-1.5 g: 15 mL;

(3) immersing the mixture obtained in the step (2) in an alkaline solution for alkali bath treatment, and standing overnight;

wherein the concentration of the alkaline solution is 0.1-10 mol/L;

(4) and (4) reacting the product obtained in the step (3) at the temperature of 90-220 ℃ for 18h to obtain the cadmium sulfide @ hydrothermal carbon composite photocatalytic material.

2. The preparation method of cadmium sulfide @ hydrothermal carbon composite photocatalytic material as claimed in claim 1, wherein in the step (3), the volume ratio of the acetic acid solution to the alkaline solution is 1: 10.

3. the preparation method of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material as claimed in claim 1, wherein in the step (1), the ratio of the cadmium acetate, thiourea, water, polyacrylic acid and ammonia water is 1 mmol: 3 mmol: 70mL of: 300 uL: 300 uL.

4. The preparation method of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material as claimed in claim 1, wherein in the step (1), the heating reaction temperature is 180 ℃ and the heating reaction time is 6 hours.

5. The preparation method of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material as claimed in claim 1, wherein in the step (1), the reaction product is centrifuged with deionized water and ethanol respectively; the drying conditions were: at 50 ℃ for 24-48 h.

6. The preparation method of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material as claimed in claim 1, wherein in the step (2), the ratio of the cadmium sulfide quantum dots to the chitosan to the acetic acid solution is 0.005 g: 0.5 g: 15 mL; the acetic acid solution had a concentration of 2% by volume.

7. The method for preparing cadmium sulfide @ hydrothermal carbon composite photocatalytic material according to claim 1, wherein in the step (3), the alkaline solution is a KOH solution, a NaOH solution or Na solution₂CO₃And (3) solution.

8. The application of the prepared cadmium sulfide @ hydrothermal carbon composite photocatalytic material in photocatalytic degradation of methylene blue in any one of claims 1 to 7.

9. The use of claim 8, wherein the cadmium sulfide @ hydrothermal carbon composite photocatalytic material is uniformly mixed with a methylene blue solution and a KOH solution in a dark environment, and then the mixture is reacted under a light condition.

10. The use according to claim 9, wherein the concentration of the methylene blue solution is 1 to 7 mg/ml; the concentration of the KOH solution is 0.03-0.12 mol/L; the reaction time is 0-90 min but not 0.

Technical Field

The invention relates to a novel, simple and convenient preparation method of a cadmium sulfide @ hydrothermal carbon composite photocatalytic material and application of the composite photocatalytic material in methylene blue degradation, and belongs to the field of photocatalysis.

Background

The photocatalysis principle is based on the oxidation-reduction capability of the photocatalyst under the condition of illumination, so that the application purposes of pollutant degradation, organic synthesis, nitrogen fixation, hydrogen production and the like are realized. In general, a photocatalytic degradation reaction uses a semiconductor as a catalyst and light as energy to degrade organic substances into carbon dioxide and water. The photocatalysis technology is an efficient and safe environment-friendly environmental purification technology, and the improvement of indoor air and sewage quality is approved by the international academia. The principle of photocatalysis is to excite a semiconductor material by light, and take part in oxidation-reduction reaction by electrons and holes generated on the surface of the semiconductor material. When light with energy greater than or equal to the energy gap is irradiated onto the semiconductor surface, electrons in the valence band thereof will be excited to transition to the conduction band, leaving relatively stable holes in the valence band, thereby forming electron-hole pairs. Due to the large number of defects in the nanomaterial, these defects can trap electrons or holes and prevent the recombination of electrons and holes. These trapped electrons and holes diffuse to the surface of the material, respectively, creating a strong redox potential. Many kinds of photocatalysts including titanium dioxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, etc., and also part of silver salts, porphyrins, etc., have catalytic effects, but they basically have a disadvantage of loss, i.e., consumption of themselves before and after the reaction. Therefore, it is important to develop a highly efficient and stable photocatalyst.

Disclosure of Invention

The invention aims to provide a novel and simple preparation method of a cadmium sulfide @ hydrothermal carbon composite photocatalytic material and application of the composite photocatalytic material in methylene blue degradation, aiming at the problems of poor catalytic performance, low stability and the like of a catalytic material in the existing photocatalytic system. The invention takes chitosan as a raw material and utilizes a simple method to prepare the composite photocatalytic material with high catalytic activity and good stability. The raw material chitosan used in the invention has wide sources, is cheap and easy to obtain, and has good biocompatibility, safety and biodegradability. The synthesis method is simple and easy to control, and is 'green' and pollution-free.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a cadmium sulfide @ hydrothermal carbon composite photocatalytic material comprises the following steps:

(1) adding cadmium acetate and thiourea into water, uniformly stirring, slowly adding polyacrylic acid and ammonia water, uniformly stirring, heating and reacting for 5-6 hours at a high temperature of 150-200 ℃ after the solution is clarified, centrifuging and drying a reaction product to obtain cadmium sulfide quantum dots; wherein the proportion relation of the cadmium acetate, the thiourea, the water, the polyacrylic acid and the ammonia water is 0.5-5 mmol: 0.5-5 mmol: 40-100 mL: 50-500 uL: 50-500 uL;

(2) dispersing the cadmium sulfide quantum dots obtained in the step (1) in an acetic acid solution, slowly adding chitosan, stirring until the chitosan is completely dissolved, and then performing ultrasonic defoaming; (ii) a Wherein the concentration of the acetic acid solution is 1-10% (v/v); the ratio of the cadmium sulfide quantum dots to the chitosan to the acetic acid solution is 0.001-0.05 g: 0.1-1.5 g: 15 mL;

(3) immersing the mixture obtained in the step (2) in an alkaline solution, carrying out alkaline bath treatment by using the alkaline solution, and standing overnight to obtain a formed gel material; wherein the concentration of the alkaline solution is 0.1-10 mol/L;

(4) and (3) reacting the product obtained in the step (3) at the temperature of 90-220 ℃ for 18H to obtain the cadmium sulfide @ hydrothermal carbon (CdS @ Hy-H) composite photocatalytic material.

According to the above technical solution, preferably, in the step (1), the ratio of the cadmium acetate, thiourea, water, polyacrylic acid and ammonia water is 1 mmol: 3 mmol: 70mL of: 300 uL: 300 uL.

According to the above technical solution, in step (1), the heating reaction temperature is preferably 180 ℃ and the heating reaction time is preferably 6 hours.

According to the above technical solution, preferably, in the step (1), the reaction product is centrifuged with deionized water and ethanol, respectively.

According to the above technical means, in step (1), the drying conditions are preferably as follows: at 50 ℃ for 24-48 h.

According to the above technical scheme, preferably, in the step (1), the product after the reaction is centrifuged, dried and ground into powder to obtain the cadmium sulfide quantum dots.

According to the above technical solution, preferably, in the step (3), the ratio of the cadmium sulfide quantum dots, the chitosan and the acetic acid solution is 0.005 g: 0.5 g: 15 mL.

According to the above technical solution, in step (2), the acetic acid solution preferably has a volume concentration of 2%.

According to the above technical solution, preferably, in the step (3), the alkaline solution is KOH solution, NaOH solution, or Na₂CO₃And (3) solution.

According to the above technical solution, preferably, in the step (3), the concentration of the alkaline solution is 4 mol/L.

According to the above technical solution, preferably, in the step (3), the volume ratio of the acetic acid solution to the alkaline solution is 1: 10;

according to the above technical solution, in step (4), the reaction temperature is preferably 140 ℃.

According to the technical scheme, preferably, in the step (4), the product obtained in the step (3) reacts at the temperature of 90-220 ℃ for 18 hours, and then the obtained material is cleaned, dried, uniformly crushed and sealed for storage, so that the cadmium sulfide @ hydrothermal carbon composite photocatalytic material is obtained.

The cadmium sulfide @ hydrothermal carbon composite photocatalytic material prepared by the method is applied to photocatalytic degradation of methylene blue, and is uniformly mixed with a methylene blue solution and a KOH solution in a dark environment to react under an illumination condition. The absorbance of the sample obtained by the ultraviolet spectroscopy test is converted into the degradation efficiency of methylene blue (the concentration of the degraded methylene blue can be calculated from the absorbance, and the formula is a (lg (1/T): Kbc, wherein a is the absorbance, T is the transmittance, K is the molar absorption coefficient, c is the concentration of the degraded methylene blue, and the unit is mol/L, b is the thickness of the absorption layer, and the unit is cm).

According to the technical scheme, the concentration of the methylene blue solution is preferably 1-7 mg/mL, and preferably 5 mg/mL.

According to the above technical solution, preferably, the concentration of the KOH solution is 0.03-0.12 mol/L, and preferably 0.1 mol/L.

According to the technical scheme, preferably, the reaction time is 0-90 min but not 0; the reaction temperature is room temperature, typically 25 ℃.

According to the technical scheme, preferably, the ratio of the cadmium sulfide @ hydrothermal carbon composite photocatalytic material to the methylene blue solution to the KOH solution is 0.05-0.15 g: 2.0 mL: 8mL, preferably 0.05 g: 2.0 mL: 8 mL.

The composite photocatalytic material synthesized by the method has the advantages of good stability, high catalytic activity, quick effect, low energy consumption, reusability and the like, belongs to a green synthesis method which is simple and convenient to operate and environment-friendly, is obtained by adding cadmium sulfide in the process and performing chemical crosslinking, and has the characteristics of quick effect, low energy consumption, good degradation effect, easiness in realizing industrial production and the like in the using process. The composite photocatalytic material obtained by the invention has wide application prospect in the aspect of wastewater treatment, and can also be used as one of photocatalytic degradation materials with the most application potential in the 21 st century.

The synthesis method of the invention has the following advantages:

(1) the invention adopts cheap, nontoxic, renewable, biodegradable and biocompatible chitosan as raw material to prepare the composite photocatalytic material, which is beneficial to environmental protection;

(2) the preparation method of the composite photocatalytic material is simple to operate, and the reaction conditions are easy to control;

(3) the composite photocatalytic material prepared by the invention has the advantages of quick effect, low energy consumption, good effect, easy realization of industrial production and the like in the using process;

(4) the product of the invention provides an effective solution for the problems of poor catalytic performance, low stability and the like of the catalytic material in the existing photocatalytic system.

Drawings

Fig. 1 is a graph showing the effect of different cadmium sulfide dosages on the photocatalytic degradation of methylene blue by the cadmium sulfide @ hydrothermal carbon composite photocatalytic material in example 9.

Fig. 2 is a graph showing the influence of photocatalytic degradation of methylene blue by the cadmium sulfide @ hydrothermal carbon composite photocatalytic material prepared at different treatment (reaction) temperatures in examples 11 and 9.

Detailed Description

The present invention will be further described below by way of examples for better understanding of the technical features of the present invention, but the scope of the present invention claimed is not limited thereto.