Preparation method of photocatalytic adsorption material

Abstract

The application relates to the technical field of photocatalytic adsorption materials, and discloses a preparation method of a photocatalytic adsorption material, wherein a ring-opening reaction is carried out between hydroxyl groups in nano zinc oxide and epoxy groups in epichlorohydrin to obtain hydroxypropyl chlorinated zinc oxide; chitosan is alkalized by sodium hydroxide; substitution reaction occurs between amino groups contained in the chitosan and chlorine in the hydroxypropyl chlorinated zinc oxide to obtain chitosan-loaded nano zinc oxide; 2-amino-2-methyl-1,3-propanediol and pyromellitic dianhydride are subjected to ring-opening reaction to obtain an intermediate 1; a polymerization reaction occurs between the intermediate 1 and a p-toluenesulfonic acid catalyst to obtain hyperbranched polyamide ester. Finally, the chitosan-loaded nano zinc oxide and the hyperbranched polyamide ester are stirred and mixed to obtain the photocatalytic adsorption material. The photocatalytic adsorption material prepared by the application has excellent photocatalytic adsorption effect on methylene blue.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic adsorption materials technology, specifically a method for preparing photocatalytic adsorption materials. Background Technology

[0002] In recent years, environmental problems caused by dye wastewater pollution have become increasingly prominent. Dye wastewater is characterized by its complex composition, high content of organic pollutants, poor biodegradability, and difficulty in degradation. Methylene blue, a representative compound of water-soluble azo dyes, has high color intensity and causes significant environmental pollution; therefore, the treatment of dye wastewater is currently a hot research topic.

[0003] Hyperbranched polymers possess low viscosity, no chain entanglement, good solubility, and a large number of active functional groups at their ends. Their unique three-dimensional nanoporous structure allows for ion chelation and adsorption. Chitosan, a product of chitin deacetylation, exhibits good biocompatibility and biodegradability, and is widely used in textiles, agriculture, cosmetics, and other fields.

[0004] Zinc oxide is a typical wide-bandgap direct bandgap semiconductor material with good biocompatibility, resistance to photochemical corrosion, and low toxicity, and is widely used in ultraviolet detectors, optical information storage, coatings, photocatalysis, and other fields. For example, patent application number CN107442099A discloses a sonochemical preparation method for porous zinc oxide photocatalytic materials. The prepared porous zinc oxide exhibits excellent photocatalytic performance and can effectively solve environmental pollution problems; however, its adsorption performance is poor. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a photocatalytic adsorption material. This invention prepares a hyperbranched polyamide ester and chitosan-supported nano-zinc oxide, and the prepared photocatalytic adsorption material exhibits excellent photocatalytic adsorption performance for methylene blue.

[0007] (II) Technical Solution

[0008] A method for preparing a photocatalytic adsorption material, wherein the preparation method comprises:

[0009] (1) Add intermediate 1 to a flask containing toluene solvent, stir and disperse, then add p-toluenesulfonic acid, heat to 110-130℃, polymerize for 5-10 hours, wash with ether, dry, and obtain hyperbranched polyamide ester.

[0010] (2) Dissolve chitosan and sodium hydroxide in a flask containing isopropanol solvent, heat to 30-40℃, alkalize for 2-4 hours, heat to 45-55℃, add hydroxypropyl zinc oxide and react for 3-6 hours, filter, wash with deionized water, and dry to obtain chitosan-supported nano zinc oxide.

[0011] (3) Chitosan-loaded nano zinc oxide is added to a flask containing deionized water, and then hyperbranched polyamide ester is added. The temperature is raised to 30-40℃, stirred and dispersed for 5-10 hours, and then dried to obtain the photocatalytic adsorption material.

[0012] Preferably, in step (1), the mass ratio of intermediate 1 to p-toluenesulfonic acid is 1:0.01-0.05.

[0013] Preferably, in step (2), the mass ratio of chitosan, sodium hydroxide, and hydroxypropyl zinc oxide is 1:0.15-0.3:1-1.5.

[0014] Preferably, in step (3), the mass ratio of chitosan-loaded nano zinc oxide to hyperbranched polyamide ester is 1:0.3-0.6.

[0015] Preferably, in step (1), the preparation method of intermediate 1 is as follows: under a nitrogen atmosphere, 2-amino-2-methyl-1,3-propanediol is added to a flask containing dimethylacetamide, stirred and dispersed, then pyromellitic dianhydride is added, and the mixture is stirred and reacted at 0-5°C for 5-10 hours to obtain intermediate 1. The reaction equation is as follows: .

[0016] Preferably, in the above steps, the mass ratio of 2-amino-2-methyl-1,3-propanediol to pyromellitic dianhydride is 1:0.8-1.2.

[0017] Preferably, in step (2), the preparation method of hydroxypropyl zinc oxide is as follows: nano zinc oxide is dispersed in acetone solvent, a hydrochloric acid solution with a mass fraction of 20-30% is added to it, the pH is adjusted to 4-6, epichlorohydrin is added to it, the mixture is heated to 50-60℃, reacted for 6-12 hours, cooled to room temperature, the solvent is removed by rotary evaporation, and dried to obtain hydroxypropyl zinc oxide.

[0018] Preferably, in the above steps, the mass ratio of nano zinc oxide to epichlorohydrin is 1:5-8.

[0019] (iii) Beneficial technical effects

[0020] The hydroxyl groups in nano-zinc oxide undergo a ring-opening reaction with the epoxy groups in epichlorohydrin to obtain hydroxypropyl zinc oxide chloride. Chitosan, after being alkalized with sodium hydroxide, undergoes a substitution reaction between the amino groups and the chlorine in the hydroxypropyl zinc oxide chloride to obtain chitosan-supported nano-zinc oxide. 2-Amino-2-methyl-1,3-propanediol and pyromellitic dianhydride undergo a ring-opening reaction to obtain intermediate 1. Then, p-toluenesulfonic acid catalyst is added to this intermediate, and a polymerization reaction occurs to obtain hyperbranched polyamide ester. Finally, the chitosan-supported nano-zinc oxide and the hyperbranched polyamide ester are stirred and mixed to obtain a photocatalytic adsorption material.

[0021] The photocatalytic adsorption material prepared by this invention contains hyperbranched polyamide esters with a large number of hydroxyl and carboxyl groups, and chitosan-supported nano-zinc oxide with a large number of amino and hydroxyl groups. Methylene blue molecules are positively charged, and the photocatalytic adsorption material can adsorb methylene blue in the photocatalytic adsorption material through electrostatic attraction.

[0022] The photocatalytic adsorbent material prepared in this invention contains zinc oxide, which, upon ultraviolet radiation, undergoes an excited transition of valence band electrons to the conduction band, generating holes in the valence band. These holes possess strong oxidizing properties and can oxidize hydroxide ions and water adsorbed on the zinc oxide surface into hydroxyl radicals. The thiol groups in methylene blue are chromophores; during ultraviolet degradation, they are oxidized by the hydroxyl radicals generated from photodegradation to form sulfone groups with absorption wavelengths less than 180 nm, gradually fading the blue color and thus achieving the decolorization and decomposition of methylene blue. The photocatalytic adsorbent material prepared in this invention achieves the goal of both adsorbing and degrading methylene blue, exhibiting excellent photocatalytic adsorption performance for methylene blue. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0024] Example 1

[0025] (1) Disperse 7g of nano zinc oxide in acetone solvent, add 25% hydrochloric acid solution to adjust the pH to 5, add 40g of epichlorohydrin, heat to 55℃ and react for 10h, cool to room temperature, remove the solvent by rotary evaporation, and dry to obtain hydroxypropyl zinc oxide chloride.

[0026] (2) Dissolve 6g of chitosan and 1.2g of sodium hydroxide in a flask containing isopropanol solvent, heat to 35°C, alkalize for 4h, heat to 50°C, add 8g of hydroxypropyl zinc oxide and react for 6h, filter, wash with deionized water, and dry to obtain chitosan-supported nano zinc oxide.

[0027] (3) Under a nitrogen atmosphere, 5g of 2-amino-2-methyl-1,3-propanediol was added to a flask containing dimethylacetamide, stirred and dispersed, and 5g of pyromellitic dianhydride was added. The mixture was stirred and reacted at 0°C for 6 hours to obtain intermediate 1.

[0028] (4) Add 2g to a flask containing toluene solvent to obtain intermediate 1, stir and disperse, then add 0.08g of p-toluenesulfonic acid, heat to 120℃, polymerize for 8h, wash with ether, dry, and obtain hyperbranched polyamide ester.

[0029] (5) Add 7g of chitosan-supported nano zinc oxide to a flask containing deionized water, then add 2.1g of hyperbranched polyamide ester, heat to 40℃, stir and disperse for 6h, and dry to obtain photocatalytic adsorption material.

[0030] Example 2

[0031] The difference between this embodiment and Example 1 is that the amount of hyperbranched polyamide ester used is 3.2g.

[0032] Example 3

[0033] The difference between this embodiment and Example 1 is that the amount of hyperbranched polyamide ester used is 4.3g.

[0034] Example 4

[0035] The difference between this embodiment and Example 1 is that the amount of hyperbranched polyamide ester used is 5.4g.

[0036] Comparative Example 1

[0037] The difference between this comparative example and Example 1 is that chitosan is used instead of chitosan to support nano-zinc oxide.

[0038] Comparative Example 2

[0039] The difference between this comparative example and Example 1 is that nano zinc oxide is used instead of chitosan-supported nano zinc oxide.

[0040] 1g of photocatalytic adsorbent was immersed in a 1g / L methylene blue solution and stirred in the dark for 1 hour. Then, it was placed under a UV lamp and irradiated for 60 minutes. After irradiation, the supernatant was collected, and the concentration C of methylene blue was measured using a UV spectrophotometer. The degradation rate was calculated. Degradation rate (%) = C / C0.

[0041]

[0042] As shown in the table, the photocatalytic adsorbent materials prepared in Examples 1-5 have a higher degradation rate than those in Comparative Examples 1-2. This is because Examples 1-5 contain hyperbranched polyamide ester and chitosan-supported nano-zinc oxide, while Comparative Example 1 contains only chitosan and hyperbranched polyamide ester, resulting in a poorer degradation effect on methylene blue. Comparative Example 2 contains only nano-zinc oxide and hyperbranched polyamide ester, without chitosan, and its adsorption of methylene blue is worse than that in Examples 1-5. Therefore, the photocatalytic adsorbent materials prepared in this invention have a better photocatalytic adsorption and degradation effect on methylene blue.

[0043] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. However, obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing a photocatalytic adsorption material, characterized in that, The preparation method is as follows: (1) Add intermediate 1 to a flask containing toluene solvent, stir and disperse, then add p-toluenesulfonic acid, heat to 110-130℃, polymerize for 5-10 h, wash with diethyl ether, dry, and obtain hyperbranched polyamide ester. (2) Dissolve chitosan and sodium hydroxide in a flask containing isopropanol solvent, heat to 30-40℃, alkalize for 2-4 hours, heat to 45-55℃, add hydroxypropyl zinc oxide and react for 3-6 hours, filter, wash with deionized water, and dry to obtain chitosan-supported nano zinc oxide. (3) Chitosan-loaded nano zinc oxide was added to a flask containing deionized water, and then hyperbranched polyamide ester was added. The temperature was raised to 30-40℃, stirred and dispersed for 5-10 hours, and dried to obtain the photocatalytic adsorption material. The preparation method of intermediate 1 is as follows: under a nitrogen atmosphere, 2-amino-2-methyl-1,3-propanediol is added to a flask containing dimethylacetamide, stirred and dispersed, pyromellitic dianhydride is added, and the mixture is stirred and reacted at 0-5°C for 5-10 hours to obtain intermediate 1. The preparation method of the hydroxypropyl zinc oxide is as follows: nano zinc oxide is dispersed in acetone solvent, a hydrochloric acid solution with a mass fraction of 20-30% is added to adjust the pH to 4-6, epichlorohydrin is added, the mixture is heated to 50-60℃ and reacted for 6-12 hours, cooled to room temperature, the solvent is removed by rotary evaporation, and the mixture is dried to obtain hydroxypropyl zinc oxide.

2. The method for preparing the photocatalytic adsorption material according to claim 1, characterized in that, In step (1), the mass ratio of intermediate 1 to p-toluenesulfonic acid is 1:0.01-0.

05.

3. The method for preparing the photocatalytic adsorption material according to claim 1, characterized in that, In step (2), the mass ratio of chitosan, sodium hydroxide, and hydroxypropyl zinc oxide chloride is 1:0.15-0.3:1-1.

5.

4. The method for preparing the photocatalytic adsorption material according to claim 1, characterized in that, In step (3), the mass ratio of chitosan-loaded nano zinc oxide to hyperbranched polyamide ester is 1: 0.3-0.

6.

5. The method for preparing the photocatalytic adsorption material according to claim 1, characterized in that, In the aforementioned steps, the mass ratio of 2-amino-2-methyl-1,3-propanediol to pyromellitic dianhydride is 1:0.8-1.

2.

6. The method for preparing the photocatalytic adsorption material according to claim 1, characterized in that, In the aforementioned steps, the mass ratio of nano zinc oxide to epichlorohydrin is 1:5-8.

Images