Hydrogel-based composite photocatalyst and preparation method thereof

Abstract

The invention relates to a hydrogel-based composite photocatalyst and a preparation method thereof, and belongs to the technical field of photocatalytic degradation. Specifically, an olefin functional group is introduced to the surface of an indium zinc sulfide catalyst through silanization modification, the catalyst is connected to a hydrogel skeleton through a covalent bond by means of free radical polymerization, and the hydrogel-based composite photocatalyst with good recovery performance and catalytic stability is prepared. The composite photocatalyst prepared by the invention has excellent photocatalytic performance, and can be applied to photodegradation and removal of dyes in water.

Description

Technical Field

[0001] The present invention relates to a hydrogel-based composite photocatalyst and a preparation method thereof, belonging to the technical field of photocatalytic degradation. Background Art

[0002] Eosin Y is a chemically synthesized anionic dye. It has high water solubility and is widely used in many fields such as paints, plastics, papers, leathers, optoelectronic communications, and foods. The aromatic ring skeleton in the Eosin Y molecule endows it with good chemical stability, making it difficult to decompose and causing serious environmental pollution problems. For Eosin Y in wastewater, common treatment methods include ozone oxidation, filtration, adsorption, ultrafiltration, electrochemical treatment, chemical coagulation / flocculation, and photocatalytic degradation, etc. Among them, the photocatalytic degradation method has attracted much attention due to its advantages such as green energy, high catalytic performance, simple operation, and non-toxic degradation products. Indium zinc sulfide has become a preferred photocatalyst for the photocatalytic degradation and removal of organic dyes because of its suitable electronic band structure, good chemical stability, and visible light responsiveness. However, in most studies, a large amount of catalyst is usually required for the efficient removal of organic dyes. Moreover, in the experiments of catalyst recovery, due to the small size of the catalyst particles, the recovery is difficult, and obvious catalyst loss and reduction of catalytic efficiency can be found after multiple uses. People load the photocatalyst particles onto two-dimensional substrates such as glass fibers and titanium meshes to achieve low catalyst loading and simple recovery. However, the substrates used in these studies are all opaque, and light absorption only occurs on one side of the material.

[0003] Hydrogels have the advantages of simple preparation, abundant mass transfer channels, large specific surface area, high light transmittance, and easy recovery. Loading the photocatalyst into the hydrogel can make it evenly distributed, reduce aggregation, and reduce electron-hole recombination. Existing reports on loading the photocatalyst into the hydrogel include filling the prepared photocatalyst particles into the pores of the hydrogel, or directly in-situ preparing the photocatalyst in the channels of the hydrogel. The composite photocatalysts prepared by these methods have poor chemical stability and low reusability. By grafting olefin functional groups on the surface of the photocatalyst and connecting the catalyst to the hydrogel skeleton by polymerization in a covalent bond manner, the chemical stability can be significantly improved, the recycling performance of the composite photocatalyst can be increased, and the efficient and low-cost removal of organic dyes in wastewater can be realized.

[0004] In summary, developing a composite photocatalyst with high degradation efficiency for organic dyes and easy recovery is of great significance in the treatment of wastewater containing organic dyes. Summary of the Invention

[0005] This invention patent relates to a hydrogel-based composite photocatalyst and its preparation method. Specifically, olefin functional groups are introduced onto the surface of indium zinc sulfide through a silane coupling reaction, and it is covalently bonded to the hydrogel skeleton through a polymerization reaction to prepare the hydrogel-based composite photocatalyst.

[0006] The specific preparation process of the hydrogel-based composite photocatalyst includes the following steps:

[0007] (1)Olefin functionalization modification of indium zinc sulfide

[0008] Indium zinc sulfide and a silane coupling agent are added to tetrahydrofuran at a ratio of 0.1~0.3 g / 10~20 μL, and ultrasonicated for 25~35 minutes to disperse evenly. The dispersion is heated under reflux in an oil bath at 50~60 °C for 20~24 h. After the reaction, the solid obtained by centrifugation is washed with ethanol and centrifuged for separation. After repeating the washing 5 times, it is dried.

[0009] Among them, the silane coupling agent is one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and methacryloxymethyltrimethoxysilane;

[0010] (2)Preparation of the hydrogel-based composite photocatalyst

[0011] Acrylamide monomers, 2-hydroxyethyl methacrylate, N,N-methylenebisacrylamide, and an initiator are mixed at a ratio of 20~60 mmol / 0.20~0.35 mL / 0.05~0.1 g / 0.04~0.08 mmol, dissolved in 5~12 mL of deionized water, and 1~2 mg of the above-prepared modified indium zinc sulfide is added and mixed evenly. Measure 0.5 mL of each mixed solution and pour it into a silica gel mold with a specification of 1 cm * 1 cm * 0.5 cm, seal it, and heat it in a water bath at 55~65 °C for 20~30 minutes to prepare the hydrogel. The prepared hydrogel is soaked and washed with deionized water, and the deionized water is changed every 8 hours for a total of three washes. The obtained hydrogel-based composite photocatalyst is stored in deionized water.

[0012] Among them, the acrylamide monomer is one of acrylamide, methacrylamide, N-methylacrylamide, and N,N-dimethylacrylamide, and the initiator is one of potassium persulfate, ammonium persulfate, and azobisisobutyronitrile.

[0013] The hydrogel-based composite photocatalyst prepared by the present invention exhibits excellent photocatalytic degradation performance for eosin Y in aqueous solution. In addition, the raw materials for the preparation process of the present invention are easily available, the cost is low, the reaction conditions are mild, the reaction is easy to control, and it is effectively suitable for large-scale preparation. Description of the Drawings

[0014] Figure 1 Scanning electron microscope (SEM) image of the hydrogel-based composite photocatalyst of the present invention;

[0015] Figure 2 Mott-Schottky electrochemical curve of the hydrogel-based composite photocatalyst of the present invention;

[0016] Figure 3 Removal rate of the hydrogel-based composite photocatalyst of the present invention during recycling in photocatalytic degradation of eosin Y. Detailed implementation manners

[0017] The present invention will be further described below with reference to the accompanying drawings in the embodiments of the present invention, but the present invention is not limited to the following embodiments. The indium zinc sulfide is semiconductor particles with a petal-like morphology prepared according to the literature method. The other methods are conventional methods unless otherwise specified. The raw materials can be obtained from public commercial channels unless otherwise specified.

[0018] Example 1

[0019] 1. Preparation of the hydrogel-based composite photocatalyst

[0020] (1) ZnCl2, InCl3·4H2O, and thioacetamide were dissolved in a mixed solution of 15 mL of deionized water and 15 mL of ethanol according to the ratio of 0.054 g / 0.23 g / 0.24 g. The mixture was vigorously stirred for 20 min, then poured into a 100 mL reaction kettle and reacted at 180 °C for 24 h. After natural cooling to room temperature, the precipitated solid was centrifuged, washed three times with deionized water and ethanol respectively, and dried at 60 °C to obtain yellow indium zinc sulfide.

[0021] (2) Olefin functionalization modification of indium zinc sulfide

[0022] Indium zinc sulfide and methacryloxypropyltrimethoxysilane were added to 10 mL of tetrahydrofuran according to the ratio of 0.1 g / 10 μL and sonicated for 30 minutes. The dispersion was heated in an oil bath at 60 °C for 21 h. After the reaction, the centrifuged solid was washed with ethanol, centrifuged and separated, and dried after repeating the washing 5 times.

[0023] (2) Preparation of the hydrogel-based composite photocatalyst

[0024] Acrylamide, 2-hydroxyethyl methacrylate, N,N'-methylenebisacrylamide, and potassium persulfate were mixed in a ratio of 1.42 g / 0.25 mL / 0.05 g / 10.8 mg, dissolved in 10 mL of deionized water, and 1 mg of the prepared modified indium zinc sulfide was added and mixed evenly. 0.5 mL of each mixed solution was measured and put into a silica gel mold with a specification of 1 cm * 1 cm * 0.5 cm, sealed, and heated in a water bath at 65 °C for 20 minutes to prepare the hydrogel. The prepared hydrogel was soaked and washed with deionized water, and the deionized water was changed every 8 hours for a total of three washes. The obtained hydrogel-based composite photocatalyst was stored in deionized water.

[0025] 2. Material Characterization

[0026] Figure 1 : The surface morphology of the composite catalyst was characterized by scanning electron microscopy (SEM). It can be seen from the figure that the prepared hydrogel-based composite material has a rich pore structure, and the pore size is about 20 - 30 μm, providing rich reaction sites for the entry and degradation of organic dyes.

[0027] Figure 2 : The electrochemical properties of the composite catalyst were characterized by Mott-Schottky test. By processing the test curves at different scanning rates, it was found that the conduction band potential of the catalyst material is -1.2 V.

[0028] Example 2

[0029] Application of Hydrogel-Based Composite Photocatalyst in Degradation and Removal of Aqueous Solution Containing Organic Dye

[0030] Recycling experiment of the catalyst: The hydrogel-based composite photocatalyst prepared in Example 1 (each 1 cm * 1 cm * 0.5 cm) was used to catalytically degrade 10 mL of eosin Y aqueous solution with a concentration of 100 mg / L under sunlight irradiation for 90 minutes. After the reaction was completed, the hydrogel was taken out, soaked in deionized water for 12 hours, washed, and used for the next cycle experiment. The results are as Figure 3 shown. After 15 cycles of use, the degradation efficiency of the catalyst for eosin Y still remained above 90%. This indicates that the hydrogel-based composite photocatalyst has good stability and reusability.

Claims

1. A hydrogel-based composite photocatalyst, characterized in that: A functional group containing an olefin is grafted onto the surface of an indium zinc sulfide photocatalyst through a silane coupling reaction; A polymerization monomer, a crosslinking agent, an initiator and the grafted indium zinc sulfide are mixed to prepare a hydrogel-based composite photocatalyst.

2. According to the preparation process described in claim 1, characterized in that: (1) Olefin functionalization modification of indium zinc sulfide Indium zinc sulfide and a silane coupling agent are added to 10-15 mL of tetrahydrofuran at a ratio of 0.1-0.3 g / 10-20 μL, and ultrasonic dispersion is carried out for 25-35 minutes to make it uniform. The dispersion liquid is heated and refluxed in an oil bath at 50-60 °C for 20-24 h. After the reaction, the solid obtained by centrifugation is washed with ethanol and centrifuged for separation. After repeating the washing 5 times, it is dried; Among them, the silane coupling agent is one of methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, and methacryloxymethyltrimethoxysilane; (2) Preparation of hydrogel-based composite photocatalyst An acrylamide monomer, 2-hydroxyethyl methacrylate, N,N-methylenebisacrylamide, and an initiator are mixed at a ratio of 20-60 mmol / 0.20-0.35 mL / 0.05-0.1 g / 0.04-0.08 mmol, dissolved in 5-12 mL of deionized water, and 1-2 mg of the modified indium zinc sulfide prepared above is added and mixed evenly. Measure 0.5 mL of each mixed solution and pour it into a silica gel mold with a specification of 1 cm * 1 cm * 0.5 cm, seal it, and heat it in a water bath at 55-65 °C for 20-30 minutes to prepare a hydrogel. The prepared hydrogel is soaked and washed with deionized water, and the deionized water is changed every 8 hours, and the washing is carried out three times in total. The obtained hydrogel-based composite photocatalyst is stored in deionized water; Among them, the acrylamide monomer is one of acrylamide, methacrylamide, N-methylacrylamide, and N,N-dimethylacrylamide, and the initiator is one of potassium persulfate, ammonium persulfate, and azobisisobutyronitrile.

3. An application of the hydrogel-based composite photocatalyst according to claim 1, characterized in that: The composite photocatalyst can be used for photocatalytic degradation and removal of organic dye eosin Y in an aqueous solution.

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