3-Hydroxythiophenol-formaldehyde resin and its preparation method and application

Abstract

The present invention discloses a 3-hydroxythiophenol-formaldehyde resin (S-RF) photocatalyst and its preparation method and application. The resin can be well applied in the photocatalytic H2O2 production system, and the photocatalyst can be further applied to the photocatalytic-self-Fenton (without adding H2O2) degradation of organic pollutants. The present invention uses 3-hydroxythiophenol and paraformaldehyde as raw materials, prepolymerizes at room temperature under the catalysis of ammonia water, and then transfers them to an oven and heats to 200-250°C for hydrothermal reaction for 6-24 hours. The beneficial effects of the present invention are: the required raw materials are low in price, the method has good repeatability, and can be synthesized on a large scale; the material prepared by the present invention can be used for photocatalytic reduction of oxygen to generate H2O2, with high reaction efficiency and simple operation. It also has a high degradation efficiency when applied to the photo-self-Fenton degradation of organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of organic semiconductor materials, and in particular to a 3-hydroxythiophenol-formaldehyde resin and a preparation method and application thereof, in particular to an application thereof as a photocatalyst in the photocatalytic synthesis of H2O2 and the photocatalytic auto-Fenton (without the addition of H2O2) degradation of organic pollutants. Background Art

[0002] As one of the world's most important chemicals, H2O2 is widely used in the medical industry, chemical production, wastewater treatment, and other fields. Furthermore, H2O2 is a high-density energy carrier and can serve as both an oxidant and a reductant in single-chamber fuel cells. The theoretical output voltage of such fuel cells is 1.09V, comparable to the output potential of conventional hydrogen fuel cells (1.23V). Currently, over 95% of H2O2 is produced via the anthraquinone process. This requires multiple hydrogenation and oxidation steps, resulting in extremely high energy consumption and the production of numerous hazardous byproducts, making it incompatible with green chemistry. The direct hydrogen-oxygen reaction method, due to its harsh reaction conditions and explosion risk, has limited industrial production. Photocatalytic H2O2 production, using H2O and O2 as raw materials, solar energy, and semiconductor materials as photocatalysts, is gentle, safe, environmentally friendly, and consistent with sustainable development principles. Over the past decade, research has focused on developing novel photocatalysts to achieve efficient, stable, and scalable H2O2 production.

[0003] At present, most photocatalysts still have problems such as narrow light absorption range, weak or no absorption in the visible light region, insufficient active sites, inappropriate band gap, and inability to simultaneously oxidize water and reduce oxygen. The metal ions on some inorganic photocatalysts will even catalyze the generated H2O2 to decompose again. As a new type of photocatalyst, resorcinol formaldehyde resin has a light absorption range that can reach the infrared region, high catalytic activity, and a suitable band gap. However, there are still problems such as insufficient active sites and poor carrier separation efficiency. In addition, the current Fenton reaction usually requires the additional addition of H2O2, and the Fenton reaction rate is often affected by Fe 3+ Converted to Fe 2+ The impact of rate.

[0004] Based on the above reasons, this application is filed. Summary of the Invention

[0005] Based on the above reasons, and in response to the problems or deficiencies in the prior art, the present invention aims to provide a 3-hydroxythiophenol-formaldehyde resin, a preparation method, and applications thereof, to address or at least partially address the aforementioned technical deficiencies in the prior art. The resin material prepared by the present invention has a wide light absorption range, extending to 800 nm, significantly improving the utilization rate of sunlight. As a metal-free organic semiconductor material, this resin (polymer) has promising application prospects in the field of artificial photosynthesis. It can be used for the efficient synthesis of H2O2 by oxygen reduction. Furthermore, the resin photocatalyst can be used in a photocatalytic-auto-Fenton reaction (without the addition of H2O2) to effectively degrade organic pollutants.

[0006] In order to achieve one of the above purposes of the present invention, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing 3-hydroxythiophenol-formaldehyde resin, the method specifically comprising the following steps:

[0008] (1) At room temperature, 3-hydroxythiophenol, paraformaldehyde, and ammonia water are added to deionized water in order according to the ratio, and then stirred for reaction for 5 to 15 minutes to obtain a prepolymer solution;

[0009] (2) The prepolymer solution obtained in step (1) is transferred to a high-temperature reactor, sealed, and then the reactor is heated to 200-250° C. for a hydrothermal reaction for 6-24 hours. After the reaction is completed, the reactor is naturally cooled to room temperature, and the obtained product is centrifuged, washed, and dried to obtain the 3-hydroxythiophenol-formaldehyde resin.

[0010] Furthermore, in the above technical solution, the molar ratio of 3-hydroxythiophenol, paraformaldehyde, and ammonia in step (1) is 1:1:1 to 1:4:1. As a preferred embodiment of the present invention, the molar ratio of 3-hydroxythiophenol, paraformaldehyde, and ammonia is 1:2:1.

[0011] Furthermore, in the above technical solution, the molecular weight of the paraformaldehyde in step (1) is between 20,000 and 110,000. Paraformaldehyde is slightly soluble in water, and under alkaline catalysis, paraformaldehyde decomposes at about 80°C to generate HCHO monomer, which then reacts.

[0012] Furthermore, in the above technical solution, the mass fraction of the ammonia water in step (1) is 25% to 28%.

[0013] Furthermore, in the above technical solution, the stirring reaction in step (1) refers to a prepolymerization reaction of 3-hydroxythiophenol and paraformaldehyde under the action of ammonia as a catalyst: under the catalytic action of ammonia, the hydroxyl group on the 3-hydroxythiophenol is deprotonated to form a 3-hydroxythiophenol anion, which then undergoes a hydroxymethylation reaction with the paraformaldehyde in the solution. The formed methyl intermediate condenses to form a methylene ether bridge, which then reacts to produce a 3-hydroxythiophenol-formaldehyde resin.

[0014] Furthermore, in the above technical solution, the temperature of the hydrothermal reaction in step (2) is preferably 250° C., and the time of the hydrothermal reaction is preferably 24 h.

[0015] Furthermore, in the above technical solution, the washing in step (2) is specifically to first use deionized water to wash the product obtained by centrifugation until the pH of the supernatant is neutral, then use anhydrous ethanol and deionized water to wash alternately until the supernatant is clear, and finally use anhydrous ethanol to wash again.

[0016] Furthermore, in the above technical solution, the drying temperature in step (2) is 40-80°C, and the drying time is 8-12 hours. As a preferred embodiment of the present invention, the drying temperature in step (2) is preferably 60°C, and the drying time is preferably 10 hours.

[0017] The preparation method of the present invention uses 3-hydroxythiophenol and paraformaldehyde as reaction precursors for synthesizing 3-hydroxythiophenol-formaldehyde resin, with ammonia as a basic catalyst. The reaction mechanism of the present invention is as follows: Under the catalysis of ammonia, 3-hydroxythiophenol deprotonates to form an anion, which undergoes a hydroxymethylation reaction with the formaldehyde formed by dissociation of paraformaldehyde. The resulting methyl intermediate condenses to form a methylene ether bridge, subsequently producing a methylene-bridged resin. Furthermore, under high temperature and high pressure hydrothermal conditions, the hydroxyl group in the hydroxymethyl intermediate is released to form a quinone methyl intermediate, which undergoes a nucleophilic addition reaction with the 3-hydroxythiophenol anion to produce a resin with a DA structure.

[0018]

[0019] The second object of the present invention is to provide 3-hydroxythiophenol-formaldehyde resin prepared by the above method.

[0020] The third object of the present invention is to provide the use of 3-hydroxythiophenol-formaldehyde resin prepared by the above-mentioned method as a photocatalyst in the photocatalytic synthesis of H2O2.

[0021] A fourth object of the present invention is to provide the use of the 3-hydroxythiophenol-formaldehyde resin prepared by the above-mentioned method as a photocatalyst in the photocatalytic auto-Fenton degradation of organic pollutants.

[0022] Furthermore, in the above technical solution, the organic pollutant is oxytetracycline.

[0023] Furthermore, the application method of the above technical solution is specifically as follows:

[0024] Prepare an iron salt solution, then mix the iron salt solution with oxytetracycline hydrochloride according to a ratio to prepare an iron ion-containing oxytetracycline solution; then add 3-hydroxythiophenol-formaldehyde resin photocatalyst to the iron ion-containing oxytetracycline solution, disperse it evenly, adjust the pH of the resulting dispersion to 2.0-4.0, and continue stirring.

[0025] Furthermore, in the above technical solution, the molar ratio of the iron salt to oxytetracycline hydrochloride is 3:7.

[0026] Furthermore, in the above technical solution, the molar ratio of the 3-hydroxythiophenol-formaldehyde resin photocatalyst to oxytetracycline hydrochloride is 17:1.

[0027] Furthermore, in the above technical solution, the pH of the dispersion is preferably 3.0.

[0028] Furthermore, in the above technical solution, the stirring time is 2 to 4 hours.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention introduces a thiol group into a resorcinol-formaldehyde resin by replacing resorcinol with 3-hydroxythiophenol, and synthesizes the 3-hydroxythiophenol-formaldehyde resin in a single step via a high-temperature hydrothermal reaction. The introduction of the thiol group increases the photocatalyst's active sites, enhances its oxygen adsorption capacity, and improves its carrier separation efficiency, thereby significantly increasing its photocatalytic H2O2 production activity. The H2O2 concentration in the solution can reach 2 mM after 1 hour of illumination, which is 3.4 times that of a resorcinol-formaldehyde resin synthesized under the same conditions. The resin is used in a photocatalytic self-Fenton system to degrade oxytetracycline, achieving a degradation efficiency of 84% within 2 hours. The 3-hydroxythiophenol-formaldehyde resin photocatalytic self-Fenton reaction system performs better in degrading oxytetracycline than a phenolic resin self-Fenton reaction system and a single photocatalytic and Fenton reaction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1The photocatalytic H2O2 production performance of 3-hydroxythiophenol-formaldehyde resin photocatalysts with different raw material ratios prepared in Examples 1-4 of the present invention;

[0033] Figure 2 The photocatalytic H2O2 production performance of the 3-hydroxythiophenol formaldehyde resin photocatalyst prepared at different reaction temperatures in Examples 1, 5-9 of the present invention;

[0034] Figure 3 This is a comparison of the photocatalytic H2O2 production performance of 3-hydroxythiophenol formaldehyde resin photocatalysts prepared at different synthesis times in Examples 1, 10-12 of the present invention;

[0035] Figure 4 The scanning electron microscope and elemental surface scan of the 3-hydroxythiophenol-formaldehyde resin photocatalyst material prepared in Example 1 of the present invention;

[0036] Figure 5 is an X-ray photoelectron spectrum (XPS) of the 3-hydroxythiophenol-formaldehyde resin photocatalyst material prepared in Example 1 of the present invention;

[0037] Figure 6 is an infrared spectrum of the 3-hydroxythiophenol-formaldehyde resin photocatalyst material prepared in Example 1 of the present invention;

[0038] Figure 7 The photo, ultraviolet diffuse reflectance spectrum and Tauc curve of the 3-hydroxythiophenol-formaldehyde resin photocatalyst material prepared in Example 1 of the present invention are shown;

[0039] Figure 8 is the ultraviolet photoelectron spectrum of the 3-hydroxythiophenol-formaldehyde resin photocatalyst material prepared in Example 1 of the present invention;

[0040] Figure 9 2 -TPD curve comparison of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1;

[0041] Figure 10 3-Hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1 are fluorescence spectra;

[0042] Figure 11 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1 are Mott-Schottky curves;

[0043] Figure 123-Hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the impedance diagram of the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1;

[0044] Figure 13 is the surface potential of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1;

[0045] Figure 14 is the zeta potential of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1;

[0046] Figure 15 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin photocatalyst material prepared in Comparative Example 1 are plotted against time for the photocatalytic production of hydrogen peroxide;

[0047] Figure 16 The C / C of oxytetracycline degraded by photocatalytic self-Fenton reaction of 3-hydroxythiophenol-formaldehyde resin prepared in Example 2 of the present invention o The relationship curve with time. DETAILED DESCRIPTION

[0048] The present invention provides a 3-hydroxythiophenol-formaldehyde resin (S-RF) photocatalyst, its preparation method and application. The resin can be well used in the photocatalytic H2O2 production system, and the photocatalyst can be further applied to the photocatalytic-self-Fenton (without adding H2O2) degradation of organic pollutants. The present invention uses 3-hydroxythiophenol and formaldehyde as raw materials, first prepolymerizes them at room temperature under the catalysis of ammonia water, and then transfers them to an oven and heats them to 200-250°C for hydrothermal reaction for 6-24 hours. The beneficial effects of the present invention are: the required raw materials are low in price, the method has good repeatability, and can be synthesized on a large scale; the material prepared by the present invention can be used for photocatalytic reduction of oxygen to generate H2O2, with high reaction efficiency and simple operation. It also has a high degradation efficiency when applied to the photocatalytic self-Fenton degradation of organic pollutants.

[0049] The present invention is further described in detail below through implementation cases.

[0050] The equipment and raw materials used in the present invention are all commercially available or commonly used in the art. Unless otherwise specified, the raw materials and catalysts used in the examples of this application were purchased from commercial sources. For example, 3-hydroxythiophenol and paraformaldehyde were purchased from Beijing Bailingwei Technology Co., Ltd.; 25% to 28% ammonia water was purchased from Hangzhou Pingyao Heshun Chemical Reagent Factory.

[0051] Unless otherwise specified, the methods in the following embodiments are all conventional methods in the art.

[0052] Example 1

[0053] A 3-hydroxythiophenol-formaldehyde resin (S-RF) photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0054] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0055] Example 2

[0056] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0057] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.03g (0.001mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The product was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0058] Example 3

[0059] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0060] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.09g (0.003mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0061] Example 4

[0062] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0063] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.12g (0.004mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 24 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0064] Example 5

[0065] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0066] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 200°C for 24 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0067] Example 6

[0068] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0069] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 210°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0070] Example 7

[0071] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0072] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 220°C for 24 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0073] Example 8

[0074] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0075] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 230°C for 24 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0076] Example 9

[0077] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0078] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 240°C for 24 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0079] Example 10

[0080] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0081] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0082] Example 11

[0083] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0084] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 12 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0085] Example 12

[0086] A 3-hydroxythiophenol-formaldehyde resin photocatalyst in this embodiment is prepared by the following method, with the following steps:

[0087] 0.126g (0.001mol) of 3-hydroxythiophenol and 0.06g (0.002mol) of paraformaldehyde were dispersed in 40mL of deionized water. 100μL of 25% to 28% ammonia water was added as a catalyst. The mixture was stirred at room temperature for 10 minutes to produce a prepolymer solution. The prepolymer solution was then transferred to a 50mL high-temperature reactor and reacted at 250°C for 18 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged. The product was first washed with deionized water until the supernatant reached a pH of 7. The supernatant was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear, and then washed once more with anhydrous ethanol. Finally, the washed product was dried in a vacuum drying oven at 60°C for 10 hours to produce a 3-hydroxythiophenol-formaldehyde resin sample.

[0088] Comparative Example 1

[0089] A resorcinol-formaldehyde resin (RF) photocatalyst of this comparative example was prepared by the following method, comprising the following steps:

[0090] 0.11g of resorcinol and 0.06g of paraformaldehyde were dispersed in 40mL of deionized water, followed by the addition of 100μL of aqueous ammonia as a catalyst. The mixture was stirred at room temperature for 10 minutes. The solution was then transferred to a 50mL reactor and reacted at 250°C for 24 hours. After cooling to room temperature, the mixture was centrifuged and the product was washed with deionized water until the supernatant reached a pH of 7. The product was then washed alternately with anhydrous ethanol and deionized water until the supernatant was clear. Finally, the cleaned product was dried in a vacuum drying oven at 60°C for 10 hours to obtain a resorcinol-formaldehyde resin sample.

[0091] Application Example 1

[0092] The 3-hydroxythiophenol-formaldehyde resin (S-RF) photocatalyst prepared in Example 1 of the present invention and the resorcinol-formaldehyde resin (RF) photocatalyst prepared in Comparative Example 1 were used to photocatalytically synthesize H2O2. Taking S-RF as an example, the specific method for determining the activity of H2O2 produced by the photocatalytic reaction is as follows:

[0093] Take 50mg of the 3-hydroxythiophenol-formaldehyde resin photocatalyst prepared in Example 1, add 30mL of ultrapure water, and ultrasonicate for 5min to make it evenly dispersed. Bubble oxygen into the solution for 30min and stir under dark conditions at a stirring speed of 100rpm to saturate the solution with oxygen. Use a 300W xenon lamp (λ>420nm) as the light source and sample after illumination at 0℃ for 1h. Stir continuously during the reaction. Take 1mL of the reaction solution every 1h and filter it with a 0.45μm needle. The filtered solution is stored in a centrifuge tube and cooled for storage. Take 250μL of the filtered reaction solution and dilute it to 4mL. Add 0.1mL of potassium iodide solution (0.4M), 0.1mL of potassium hydrogen phthalate solution (0.1M), and 0.1mL of ammonium molybdate solution (0.0001M), shake well and let it stand for 15min, and measure its 350nm (I3 - ) UV absorption intensity. The test range is 200-550nm. The determination of H2O2 concentration in the solution is based on the fact that H2O2 can oxidize KI to I2, and I2 dissolves in KI to form I3 - According to Beer-Lambert quantification, I3 - The absorbance is proportional to its concentration, and I3 can be calculated by the marking method. - The concentration of H2O2 was further calculated based on the stoichiometric relationship of the reaction between H2O2 and KI.

[0094] H2O2 calibration line preparation: Dilute 50 μL of 30% H2O2 to 50 mL to obtain a 10 mM H2O2 solution. Dilute 12, 20, 28, 36, and 44 μL of this 10 mM H2O2 solution to 4 mL, respectively, to obtain 30, 50, 70, 90, and 110 μM H2O2 solutions. Use the 30, 50, 70, 90, and 110 μM H2O2 solutions for iodine titration.

[0095] Application Example 2

[0096] The 3-hydroxythiophenol-formaldehyde resin (S-RF) photocatalyst prepared in Example 1 of the present invention was used to degrade oxytetracycline by photocatalytic self-Fenton reaction. The specific method for determining the activity of oxytetracycline degradation is as follows:

[0097] Weigh 10mg of FeCl3 to make 1L of 10mg / L iron ion solution. Take 50mL of iron ion solution and add 40mg of oxytetracycline hydrochloride to make 800mg / L iron ion oxytetracycline solution. Take 5mL of this iron ion oxytetracycline solution and add 45mL of iron ion solution to dilute it to make 80mg / L iron ion oxytetracycline solution. Add 30mg of 3-hydroxythiophenol-formaldehyde resin photocatalyst prepared in Example 1 to this solution, ultrasonicate for 10min, adjust the pH to 3.0, start light-proof adsorption equilibrium, and continue stirring during the adsorption process. Take samples every hour to measure the ultraviolet absorption spectrum once. After the sample adsorbs for 4h, it can fully reach adsorption equilibrium. After adsorption equilibrium, pass oxygen for 30min, then use a 300W xenon lamp (λ>420nm) as the light source, and sample every 30min. Record the absorbance value at the characteristic absorption peak (λ=350nm) of oxytetracycline using ultraviolet absorption spectrum.

[0098] In the above-mentioned application example 2: 0.5 mg of ferric chloride was used in one reaction, and its relative molecular mass was 162, and its molar weight was 0.003 mmol; 4 mg of oxytetracycline hydrochloride was used, and its relative molecular mass was 533, and its molar weight was 0.007 mmol; the relative molecular mass of 3-hydroxythiophenol-formaldehyde resin was 247, calculated as a monomer, and 30 mg was used in one experiment, and its molar weight was 0.12 mmol.

[0099] Comparative Application Example 1

[0100] The resorcinol-formaldehyde (RF) resin photocatalyst prepared in Comparative Example 1 of the present invention was used to degrade oxytetracycline by photocatalytic self-Fenton reaction. The specific method for determining the activity of oxytetracycline degradation is as follows:

[0101] Weigh 10mg of FeCl3 to make 1L of 10mg / L iron ion solution. Take 50mL of iron ion solution and add 40mg of oxytetracycline hydrochloride to make 800mg / L iron ion oxytetracycline solution. Take 5mL of this iron ion oxytetracycline solution and add 45mL of iron ion solution to dilute it and make 80mg / L iron ion oxytetracycline solution. Add 30mg of the resorcinol-formaldehyde resin photocatalyst prepared in Example 1 to this solution, ultrasonicate for 10min, adjust the pH to 3.0, start light-proof adsorption equilibrium, and continue stirring during the adsorption process. Take samples every hour to measure the ultraviolet absorption spectrum once. After the sample adsorbs for 4h, it can fully reach adsorption equilibrium. After adsorption equilibrium, pass oxygen for 30min, then use a 300W xenon lamp (λ>420nm) as the light source, and sample every 30min. Record the absorbance value at the characteristic absorption peak (λ=350nm) of oxytetracycline using ultraviolet absorption spectrum.

[0102] Comparative Application Example 2

[0103] The 3-hydroxythiophenol-formaldehyde (S-RF) resin photocatalyst prepared in Example 1 of the present invention was used to photocatalytically degrade oxytetracycline. The specific method for determining the activity of oxytetracycline degradation is as follows:

[0104] Take 4 mg of oxytetracycline hydrochloride and use deionized water to prepare an 80 mg / L oxytetracycline solution. Add 30 mg of 3-hydroxythiophenol-formaldehyde resin photocatalyst prepared in Example 1 to this solution, ultrasonicate for 10 minutes, adjust the pH to 3.0, start light-proof adsorption equilibrium, and stir continuously during the adsorption process. Take samples every hour and measure the ultraviolet absorption spectrum once. The sample can fully reach adsorption equilibrium after 4 hours of adsorption. After the adsorption equilibrium, pass oxygen for 30 minutes, and then use a 300W xenon lamp (λ>420nm) as the light source, and sample every 30 minutes. Use ultraviolet absorption spectrum to record the absorbance value at the characteristic absorption peak (λ=350nm) of oxytetracycline.

[0105] Comparative Application Example 3

[0106] Weigh 10 mg of FeCl3 to make 1 L of 10 mg / L iron ion solution. Take 50 mL of the iron ion solution and add 40 mg of oxytetracycline hydrochloride to make 800 mg / L iron ion oxytetracycline solution. Take 5 mL of the iron ion oxytetracycline solution and add 45 mL of the iron ion solution to dilute it to make 80 mg / L iron ion oxytetracycline solution. Adjust the pH to 3.0. After adsorption equilibrium, pass oxygen for 30 minutes, then use a 300W xenon lamp (λ>420nm) as the light source, and add 0.3 mmol H2O2 to carry out the Fenton reaction. Sampling is performed every 30 minutes. The absorbance value at the characteristic absorption peak (λ=350nm) of oxytetracycline is recorded using ultraviolet absorption spectroscopy.

[0107] The structural and performance test results are as follows:

[0108] The photocatalytic H2O2 production activities of the 3-hydroxythiophenol-formaldehyde resins with different raw material ratios prepared in Examples 1-4 under the same conditions are as follows: Figure 1 As shown, when the molar ratio of 3-hydroxythiophenol to formaldehyde is 1:2, the obtained 3-hydroxythiophenol-formaldehyde resin has the best performance, and the cumulative concentration of H2O2 produced in 1 hour is about 2mM.

[0109] The photocatalytic H2O2 production activity of 3-hydroxythiophenol-formaldehyde resins prepared at different synthesis temperatures in Examples 1 and 5-9 is as follows: Figure 2 As shown, the optimal synthesis temperature is 250℃.

[0110] The photocatalytic H2O2 production activity of 3-hydroxythiophenol-formaldehyde resins prepared at different synthesis times in Examples 1, 10-12 is as follows: Figure 3 As shown, the optimal synthesis time is 24h.

[0111] The scanning electron microscope image of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 is as follows: Figure 4 As shown, it appears as micron spheres with a particle size of approximately 1-2 μm. Elemental scanning shows that it is composed of carbon, oxygen, and sulfur.

[0112] The X-ray photoelectron spectroscopy (XPS) of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 is as follows: Figure 5 As shown, it shows that the thiol group has been successfully introduced into the phenolic resin skeleton, and the O element in the resin structure mainly exists in the form of carbonyl and hydroxyl groups.

[0113] The infrared spectrum of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 is as follows: Figure 6 As shown, it shows that there are benzene ring skeleton, thiol, hydroxyl and carbonyl groups in the resin structure, which confirms that the thiol group has been introduced into the resin skeleton.

[0114] The ultraviolet diffuse reflectance curve of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 is as follows: Figure 7 As shown, it shows that its absorption of visible light can reach 800nm and the band gap width is 2.1eV.

[0115] The ultraviolet photoelectron spectrum of the hydroxythiophenol-formaldehyde resin prepared in Example 1 is as follows: Figure 8 As shown, the calculated Fermi level is -5.16eV, and the difference between the Fermi level and the valence band maximum is 1.72eV. Figure 7 The Tauc curves of the two compounds show that their band gaps are 0.28 eV and 2.38 eV, indicating that they can thermodynamically reduce oxygen to synthesize H2O2.

[0116] The O2-TPD curves of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1 were measured using Chembet Pulsar TPR / TPD. He was used as the carrier gas and O2 as the process gas, and the test range was from room temperature to 350°C. Figure 9 As shown in the figure, it is confirmed that the O2 adsorption capacity of 3-hydroxythiophenol-formaldehyde resin is stronger than that of resorcinol-formaldehyde resin.

[0117] Fluorescence spectra of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1. The FluoroMAX-4-TCSPC fluorescence lifetime combination test system of the French company Chopin Yvonne was used to test the luminous intensity of the samples. The excitation wavelength was 370 nm. Figure 10 As shown in FIG, the figure confirms that the charge carrier separation ability of 3-hydroxythiophenol-formaldehyde resin is stronger than that of resorcinol-formaldehyde resin.

[0118] The Mott-Schottky curves of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1 were measured on a CHI760D electrochemical workstation. The Mott-Schottky curves of the samples were measured using impedance-potential (IMPE). The scanning voltage was set to -0.6 to 0.8 V vs. Ag / AgCl, the frequency was 1000 Hz, and the standing time was 2 s. Figure 11 As shown in the figure, the slopes of the graph are all positive, indicating that both resins are n-type semiconductors. The slope of 3-hydroxythiophenol formaldehyde resin is smaller than that of resorcinol-formaldehyde resin, confirming that 3-hydroxythiophenol formaldehyde resin has a higher carrier concentration.

[0119] The impedance spectra of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1 were measured on a CHI760D electrochemical workstation. The light source was a xenon lamp with a 420nm cutoff filter. The electrochemical impedance of the samples was measured using AC impedance spectroscopy. The test voltage was set to 0.5V vs. Ag / AgCl, the high frequency was 105, the low frequency was 100, and the standing time was 2s. Figure 12 As shown, the figure confirms that the charge and mass transfer resistance of 3-hydroxythiophenol-formaldehyde resin is smaller.

[0120] The surface potential of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1 was measured using a Kelvin force microscope. Figure 13 As shown in the figure, by comparison, the surface potential of 3-hydroxythiophenol-formaldehyde resin is larger and the carrier separation efficiency is higher.

[0121] The Zeta potential of the 3-hydroxythiophenol-formaldehyde resin prepared in Example 1 and the resorcinol-formaldehyde resin prepared in Comparative Example 1 was measured by a Zetasizer Nano ZS90 laser particle size analyzer. Figure 14 As shown, combined Figure 11 Compared with the surface potential in the medium, 3-hydroxythiophenol-formaldehyde resin has a larger built-in electric field, so its carrier separation and transfer efficiency is higher.

[0122] The relationship between the concentration of H2O2 produced by the photocatalyst and time in Application Example 1 is as follows: Figure 15 As shown, 3-hydroxythiophenol formaldehyde resin has higher photocatalytic activity. After 1 hour of illumination, the H2O2 concentration reaches 2mM, which is 3.4 times that of resorcinol formaldehyde resin. After 12 hours of illumination, the concentration is 7.2mM.

[0123] The relationship between the degradation of oxytetracycline by photocatalytic self-Fenton reaction and time in Application Example 2 is as follows: Figure 16The results show that the 3-hydroxythiophenol-formaldehyde resin photocatalysis-self-Fenton reaction system, under visible light irradiation, can degrade oxytetracycline by 84% within 2 hours. This shows that the 3-hydroxythiophenol-formaldehyde resin photocatalysis-self-Fenton reaction system is superior to the phenol-formaldehyde resin self-Fenton reaction system and the single photocatalysis and Fenton reaction system in degrading oxytetracycline.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a 3-hydroxythiophenol-formaldehyde resin, characterized in that: The method specifically comprises the following steps: (1) At room temperature, thiol-containing 3-hydroxythiophenol, paraformaldehyde, and ammonia water are sequentially added to deionized water in a molar ratio of 1:1:1 to 1:4:1, and then stirred for 5 to 15 minutes to obtain a prepolymer solution; (2) Transfer the prepolymer solution obtained in step (1) to a high-temperature reactor, seal it, and then heat the reactor to 200-250 o C for a hydrothermal reaction for 6 to 24 hours. After the reaction is completed, the mixture is naturally cooled to room temperature. The resulting product is centrifuged, washed, and dried to obtain the 3-hydroxythiophenol-formaldehyde resin.

2. The method according to claim 1, wherein: The molar ratio of the 3-hydroxythiophenol, paraformaldehyde and ammonia water is 1:2:

1.

3. The method according to claim 1, wherein: The temperature of the hydrothermal reaction in step (2) is 250 o C, the hydrothermal reaction time is 24 h.

4. The 3-hydroxythiophenol-formaldehyde resin prepared by the method according to any one of claims 1 to 3.

5. Use of the 3-hydroxythiophenol-formaldehyde resin prepared by the method according to any one of claims 1 to 3 as a photocatalyst in the photocatalytic synthesis of H2O2.

6. Use of the 3-hydroxythiophenol-formaldehyde resin prepared by the method according to any one of claims 1 to 3 as a photocatalyst in the photocatalytic auto-Fenton degradation of organic pollutants.

7. The use according to claim 6, characterized in that: The organic pollutant is oxytetracycline.

8. The use according to claim 6, characterized in that: The application method is as follows: Prepare an iron salt solution, then mix the iron salt solution with oxytetracycline hydrochloride according to a ratio to prepare an iron ion-containing oxytetracycline solution; then add 3-hydroxythiophenol-formaldehyde resin photocatalyst to the iron ion-containing oxytetracycline solution, disperse it evenly, adjust the pH of the resulting dispersion to 2.0~4.0, and continue stirring.

9. The use according to claim 8, characterized in that: The stirring time is 2 to 4 h.

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