Preparation method and application of hydroxyl radicals under visible light irradiation

Abstract

The invention provides a preparation method and application of hydroxyl radicals under visible light irradiation, and belongs to the technical field of photochemistry. The preparation method comprises the following steps: dissolving a dopamine compound and rutile type titanium dioxide in water to prepare a mixed solution; under a dark condition, adjusting the pH value of the mixed solution to be greater than or equal to 7; and placing the pH-adjusted mixed solution under illumination of a preset wavelength for photochemical reaction to generate hydroxyl radicals. The preparation method has the characteristics of greenness, safety, simplicity in operation, low cost, high practicability and the like.

Description

Technical Field

[0001] The invention relates to the technical field of photochemistry, and in particular to a preparation method and application of hydroxyl radicals under visible light irradiation. Background Art

[0002] Hydroxyl radicals are the most common reactive oxygen species in aqueous solutions and can non-selectively contact compounds. In aqueous systems, hydroxyl radicals are produced in the following ways: nitrate / ultraviolet light, nitrite / ultraviolet light, hydrogen peroxide / ultraviolet light, ozone, Fenton or Fenton-like reactions, photo-Fenton or other Fenton reactions (including electro-Fenton systems, high-frequency ultrasound, zero-valent iron technology), vacuum ultraviolet irradiation, and heterogeneous photocatalysis. The above methods are all limited to the preparation of hydroxyl radicals under ultraviolet irradiation, but the preparation process is relatively complicated. Sewage treatment often uses Fenton or Fenton-like reactions to produce hydroxyl radicals, but this type of reaction requires an acidic environment (pH <5), and the instability of hydrogen peroxide at ambient temperature limits the preparation of hydroxyl radicals. Summary of the invention

[0003] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present invention provides a method for preparing hydroxyl radicals under visible light irradiation and application.

[0004] According to an embodiment of one aspect of the present invention, a method for preparing hydroxyl radicals under visible light irradiation is provided, comprising: dissolving a dopamine compound and rutile titanium dioxide in water to prepare a mixed solution; adjusting the pH of the mixed solution to ≥7 under light-proof conditions; and placing the pH-adjusted mixed solution under light of a preset wavelength for a photochemical reaction to generate hydroxyl radicals.

[0005] According to an embodiment of the present invention, the dopamine compound includes dopamine hydrochloride or dopamine.

[0006] According to an embodiment of the present invention, dissolving dopamine compounds and rutile titanium dioxide in water to form a mixed solution includes: dissolving dopamine compounds in water to obtain a dopamine solution; dissolving rutile titanium dioxide in water to obtain a rutile titanium dioxide solution; and mixing the dopamine solution and the rutile titanium dioxide solution to form a mixed solution.

[0007] According to an embodiment of the present invention, the concentration of dopamine in the mixed solution is 0.5-10 mM, and the concentration of rutile titanium dioxide in the mixed solution is 0.05-1.0 g / L.

[0008] According to an embodiment of the present invention, the pH of the mixed solution is 9-11.

[0009] According to an embodiment of the present invention, the irradiation time under the preset wavelength light is 1 to 60 minutes.

[0010] According to an embodiment of the present invention, the wavelength range of the preset wavelength is greater than 300 nm.

[0011] According to an embodiment of the present invention, the wavelength range of the preset wavelength includes 400~1000nm.

[0012] According to another embodiment of the present invention, there is provided an application of hydroxyl radicals prepared by the above-mentioned preparation method in disinfection and sterilization and degradation and removal of pesticide residues.

[0013] According to an embodiment of the present invention, through the modification of dopamine compounds, rutile titanium dioxide responds to visible light. After the pH adjustment is completed in the dark, the mixed solution is exposed to light of a preset wavelength to excite rutile titanium dioxide to produce electron-hole pairs, thereby generating hydroxyl radicals with strong oxidizing ability. The present invention realizes the conversion of light energy to chemical energy by utilizing the photocatalytic effect of rutile titanium dioxide. The preparation method of the present invention provides a feasible, easy to operate, practical, green and safe way for the preparation of hydroxyl radicals. The hydroxyl radicals prepared by this method can be used for disinfection and sterilization in the living environment and the degradation and removal of pesticide residues on the surface of fruits and vegetables. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0015] Figure 1 A flow chart showing a method for preparing hydroxyl radicals under visible light irradiation according to an embodiment of the present invention is shown;

[0016] Figure 2a The magnetic field response spectra of spin trapping of rutile titanium dioxide (R) solutions with different pH values ​​under visible light irradiation according to Example 1 of the present invention are shown;

[0017] Figure 2b shows the magnetic field response spectra of spin trapping of dopamine (DA) solutions with different pH values ​​under visible light irradiation according to Example 1 of the present invention;

[0018] Figure 2c The magnetic field response spectra of spin capture of dopamine hydrochloride-rutile titanium dioxide (DA-R) solutions with different pH values ​​under visible light irradiation according to Example 1 of the present invention are shown;

[0019] Figure 3The actual curve (exp DA-R) and the fitting curve (sim DA-R) of the electron paramagnetic resonance spectrum of the dopamine hydrochloride-rutile titanium dioxide mixed solution of Example 1 of the present invention are shown;

[0020] Figure 4a The signal diagram of the DA-R mixed solution of Example 1 of the present invention through secondary spin capture is shown, wherein DA-R is the original free radical capture signal diagram, and DA-R-5% DMSO is the electron paramagnetic resonance spectrum of adding 5% dimethyl sulfoxide (DMSO) to convert part of the hydroxyl radicals into methyl radicals;

[0021] Figure 4b It is a bar graph showing the concentration change of hydroxyl radicals before and after quenching some hydroxyl radicals with 5% DMSO;

[0022] Figure 5 The graph showing the change of the hydroxyl radical generation content in the DA-R aqueous solution under visible light irradiation at pH 9-11 in Example 1 of the present invention is shown;

[0023] Figure 6 The graph showing the change of the hydroxyl radical generation content in the DA-R aqueous solution under different illumination times in Example 1 and Example 2 of the present invention is shown;

[0024] Figure 7 The magnetic field response spectrum of spin trapping of dopamine hydrochloride-anatase titanium dioxide (DA-A) under visible light irradiation of Comparative Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0025] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0027] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] In the related art, hydroxyl radicals are usually prepared under ultraviolet irradiation, but the preparation process is relatively complicated. When Fenton or Fenton-like reactions are used to produce hydroxyl radicals, the environmental requirements are relatively strict, and hydrogen peroxide is relatively unstable, making the preparation process of hydroxyl radicals relatively cumbersome.

[0029] In the process of realizing the concept of the present invention, it is found that by modifying rutile titanium dioxide with dopamine compounds, rutile titanium dioxide can respond to visible light, so that rutile titanium dioxide generates hydroxyl radicals under alkaline conditions and a given preset light wavelength.

[0030] Specifically, according to an embodiment of one aspect of the present invention, a method for preparing hydroxyl radicals under visible light irradiation is provided. Figure 1 A flow chart showing a method for preparing hydroxyl radicals under visible light irradiation according to an embodiment of the present invention is shown. Figure 1 As shown, operations S101 to S103 are included.

[0031] In operation S101, dopamine compounds and rutile titanium dioxide are dissolved in water to prepare a mixed solution.

[0032] According to an embodiment of the present invention, dopamine compounds are added to the reaction as auxiliary reagents. Rutile titanium dioxide is a semiconductor material. The mixed solution is helpful to provide an environment suitable for photochemical reactions.

[0033] In operation S102, the pH of the mixed solution is adjusted to ≥7 under light-shielding conditions.

[0034] According to an embodiment of the present invention, dopamine compounds are relatively stable when the solution is neutral or alkaline, and are easy to interact with rutile titanium dioxide. Adjusting the pH value to ≥7 helps to promote the subsequent interaction between dopamine compounds and rutile titanium dioxide under light, thereby improving the selectivity and efficiency of the photochemical reaction of rutile titanium dioxide.

[0035] In operation S103, the mixed solution after the pH adjustment is placed under light of a preset wavelength for a photochemical reaction to generate hydroxyl radicals.

[0036] According to an embodiment of the present invention, when the pH-adjusted mixed solution is exposed to light of a specific wavelength, rutile titanium dioxide absorbs photon energy, causing electrons to transition from the valence band to the conduction band, generating electron-hole pairs. The electrons and holes react with molecules in the solution, such as water molecules or oxygen molecules, to generate hydroxyl radicals (•OH) with strong oxidizing ability.

[0037] It should be noted that titanium dioxide is a naturally occurring oxide and a common semiconductor photocatalyst. At present, titanium dioxide can be used in agriculture, vehicles, electronics, energy storage, air purification, sewage treatment and other fields under light conditions. Titanium dioxide mainly exists in three forms: rutile, anatase and brookite. As a typical n-type semiconductor, the absorption peak of titanium dioxide is usually less than 400nm. Due to its wide bandgap (about 3.0-3.2eV), free radical signals are usually only generated in the ultraviolet range, which limits the scope of practical photochemical applications of titanium dioxide. Titanium dioxide has tunable optical properties. By using dopamine modification to form a catechol-type interface complex, the absorption threshold of titanium dioxide is red-shifted from the ultraviolet band to the visible light band through interfacial charge transfer, and the addition of dopamine significantly reduces the energy required to excite titanium dioxide, making the bandwidth of titanium dioxide narrower. In the process of conducting experiments related to the present invention, it was found that when titanium dioxide in the form of anatase and the like was mixed with dopamine compounds and placed under light of a preset wavelength, it was difficult to generate hydroxyl radicals; while rutile titanium dioxide was able to interact with dopamine compounds and subsequently undergo a photochemical reaction to generate hydroxyl radicals.

[0038] According to an embodiment of the present invention, dopamine compounds and rutile titanium dioxide that is insoluble in water but has good dispersibility are mixed and irradiated with relatively simple visible light, so that the photocatalyst undergoes a photochemical reaction under the condition of pH ≥ 7 to generate a relatively large amount of hydroxyl free radicals. The present invention provides a new method that is highly practical, simple to operate, feasible, and relatively green and safe.

[0039] According to an embodiment of the present invention, dopamine compounds include dopamine hydrochloride or dopamine, preferably dopamine hydrochloride. Dopamine hydrochloride is a typical polyphenol compound with a simple structure, a catechol group and an amino group. It can be converted from precursors such as L-levodopa, L-phenylalanine, and L-tyrosine, and generates melanin through a series of biochemical reactions, playing an important role in metabolism, drug synthesis, etc. These precursors are widely present in dairy products, natural plants, mammals, etc. The non-covalent polymerization and covalent self-assembly characteristics of dopamine make it play an active role in material modification, material synthesis, etc. Dopamine has the characteristics of green safety, biodegradability, mature preparation, low price and wide application. Compared with directly using dopamine to prepare dopamine solution, the chemical properties of dopamine hydrochloride at room temperature and pressure are more stable, and the cost is lower. Using dopamine hydrochloride as a reaction raw material can save costs.

[0040] According to an embodiment of the present invention, operation S101 specifically includes sub-operations S1011 to S1013.

[0041] In sub-operation S1011, the dopamine compound is dissolved in water to obtain a dopamine solution.

[0042] In sub-operation S1012, rutile titanium dioxide is dissolved in water to obtain a rutile titanium dioxide solution.

[0043] In sub-operation S1013, the dopamine solution and the rutile titanium dioxide solution are mixed to form a mixed solution.

[0044] According to an embodiment of the present invention, dopamine compounds are organic compounds with certain hydrophobicity. When directly added to a solution containing rutile titanium dioxide, self-aggregation may occur, which makes it difficult to disperse evenly. By first dissolving the dopamine compounds and then mixing them with the solution of rutile titanium dioxide, it is easier to prepare a uniformly mixed solution. In addition, rutile titanium dioxide is difficult to dissolve in water. For example, ultrasound and centrifugation can be used to promote the good dispersibility of rutile titanium dioxide in water.

[0045] According to an embodiment of the present invention, the concentration of the dopamine solution is 0.5-10 mM; the concentration of rutile titanium dioxide is 0.05-1.0 g / L.

[0046] According to an embodiment of the present invention, the concentration of dopamine in the mixed solution includes 0.5~10mM, for example, it can be 0.5mM, 1mM, 2mM, 3mM, 4mM, 5mM, 6mM, 7mM, 8mM, 9mM or 10mM, preferably 1mM. The concentration of rutile titanium dioxide in the mixed solution includes 0.05~1.0g / L, for example, it can be 0.05g / L, 0.1g / L, 0.2g / L, 0.3g / L, 0.4g / L, 0.5g / L, 0.6g / L, 0.7g / L, 0.8g / L, 0.9g / L or 1g / L, preferably 0.1g / L. Adjusting the concentrations of dopamine and rutile titanium dioxide in the above ranges respectively helps to better form a catechol-type interface complex, helps to promote rutile titanium dioxide to better respond to light of a preset wavelength, and makes the photochemical reaction more sufficient.

[0047] According to an embodiment of the present invention, the pH of the mixed solution includes 9 to 11. During the experiment, it was found that when the pH of the mixed solution was adjusted to the above range, a response signal of hydroxyl radicals appeared, indicating that a certain amount of hydroxyl radicals could be prepared. Preferably, when the pH was adjusted to 10, the response amplitude of hydroxyl radicals was higher, indicating that when pH=10, relatively more hydroxyl radicals were prepared.

[0048] According to an embodiment of the present invention, the irradiation time under the preset wavelength light is 1 to 60 minutes, for example, it can be 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes.

[0049] According to an embodiment of the present invention, the wavelength range of the preset wavelength is greater than 300nm. The preset wavelength being in the above range indicates that its wavelength range is within the ultraviolet to visible light range, and is biased towards the visible light part. The light source used may be, for example, a xenon lamp, an LED lamp, or other light sources capable of emitting longer wavelengths. The light sources of the above wavelengths are relatively safer than short-wave ultraviolet rays (UVC100~280nm) and have a better effect on the human body and the environment.

[0050] For example, the band gap of rutile titanium dioxide is about 3.2eV, and the corresponding upper limit of absorption wavelength is about 387nm, which means that the wavelengths mainly absorbed by rutile titanium dioxide include short-wave ultraviolet rays. Due to the addition of dopamine, rutile titanium dioxide can respond to longer wavelength light sources, stimulate rutile titanium dioxide to produce electron-hole pairs, and then generate hydroxyl radicals (•OH).

[0051] Preferably, the wavelength range of the preset wavelength includes 400-1000 nm. For example, a xenon lamp equipped with a UV-cut 400 cut-off filter (that is, an ultraviolet filter is added) can be used to simulate the visible light band of sunlight.

[0052] It should be noted that the prepared hydroxyl radicals can be detected by electron paramagnetic resonance spectrometer with free radical spin trapping. The hyperfine splitting constant of the spin trapping agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and the hydroxyl radical adduct (DMPO-•OH) is: α N =14.9G, α H =14.6G. (DMPO-•OH literature data α N =α H =14.9G), based on a certain error in the experiment, it can be considered that the experimental value is consistent with the literature value, confirming the formation of hydroxyl radicals.

[0053] According to another embodiment of the present invention, there is provided an application of hydroxyl radicals prepared by the above-mentioned preparation method in disinfection and sterilization and degradation and removal of pesticide residues.

[0054] According to an embodiment of the present invention, hydroxyl radicals have a high oxidizing ability and can destroy the cell wall and cell membrane of microorganisms, causing leakage of cell contents, thereby inactivating microorganisms such as bacteria and viruses. And after disinfection with hydroxyl radicals, the final products are mainly water and carbon dioxide, and no harmful residues are left, which is more environmentally friendly. When hydroxyl radicals are used to remove pesticide residues from fruits and vegetables, they can oxidatively degrade pesticide molecules (for example, organophosphorus pesticides, carbamate pesticides, etc.), and decompose them into harmless small molecules, such as carbon dioxide, water and simple inorganic substances. By degrading residual pesticides, the accumulation of pesticides on the surface of fruits and vegetables is reduced, the safety is higher, and the potential harm to human health is reduced. Furthermore, the preparation method of hydroxyl radicals can be combined with food cleaning processes, without the need for complex equipment modification, and is easy to promote and implement.

[0055] The present invention is further described below by examples, drawings and related test experiments and results thereof. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may also be implemented without these specific details. And, in the absence of conflict, the details in the following embodiments may be combined arbitrarily into other feasible embodiments.

[0056] It should be noted that the following specific examples are only for illustration, and the protection scope of the present invention is not limited thereto. The chemicals and raw materials used in the following examples are all commercially available or homemade by recognized processing methods.

[0057] Embodiment 1:

[0058] Weigh 0.0587g of dopamine hydrochloride powder (DA) in a centrifuge tube, add 1mL of ultrapure water, vortex mix, and obtain a 10mM dopamine hydrochloride solution. Weigh 0.0129g of rutile titanium dioxide powder (R) in a centrifuge tube, add 2mL of ultrapure water, vortex mix, and obtain a 1.0g / L titanium dioxide solution. The two are gradient diluted to finally obtain 10mL of 1mM dopamine hydrochloride solution and 20mL of 0.1g / L rutile titanium dioxide solution, which are used for free radical capture and identification.

[0059] Pipette 1 mL of DA solution and 2 mL of R solution respectively, vortex mix, and prepare a mixed aqueous solution of dopamine hydrochloride-rutile titanium dioxide (DA-R). Use a pH meter to adjust the DA-R mixed aqueous solution to a neutral or alkaline range (pH ≥ 7), and keep it away from light for later use.

[0060] Under irradiation with a wavelength of 400~1000nm, the light is exposed for 1-12 minutes to carry out a photochemical reaction to prepare hydroxyl free radicals.

[0061] The electron paramagnetic resonance spin capture technique is used to detect the hydroxyl radicals generated by DA-R in neutral or alkaline aqueous solution under visible light irradiation conditions. Figure 2a The magnetic field response spectra of spin trapping of rutile titanium dioxide (R) solutions with different pH values ​​under visible light irradiation according to Example 1 of the present invention are shown; Figure 2b shows the magnetic field response spectra of spin trapping of dopamine (DA) solutions with different pH values ​​under visible light irradiation according to Example 1 of the present invention; Figure 2c The magnetic field response spectra of spin capture of dopamine hydrochloride-rutile titanium dioxide (DA-R) solutions of different pH values ​​under visible light irradiation according to Example 1 of the present invention are shown. It should be noted that: Figure 2a~Figure 2c and Figure 7 The curves from bottom to top are pH=2, pH=3, pH=4, pH=5, pH=6, pH=7, pH=8, pH=9, pH=10, pH=11, and pH=12. Figure 2a~Figure 2b As shown in Figure 2, it indicates that DA and R have no magnetic field response at different pH values. Figure 2c As shown, it can be seen that the DA-R mixed aqueous solution has a response signal between pH 9 and 11, and the fluctuation of the response signal is more intense at pH 10. Bruker's Xenon software was used to deconvolute the electron paramagnetic resonance spectrum of the DA-R mixed solution at pH = 10 and perform spectrum fitting. Figure 3 The actual curve (exp DA-R) and the fitting curve (sim DA-R) of the electron paramagnetic resonance spectrum of the dopamine hydrochloride-rutile titanium dioxide mixed solution of Example 1 of the present invention are shown. Figure 3As shown, the hyperfine splitting constant of the generated hydroxyl radical and the spin trap DMPO adduct (DMPO-•OH) is: α N =14.9G,α H =14.6G (DMPO-•OH literature data α N =α H =14.9G), the experimental value is consistent with the literature value.

[0062] The specific operation of the electron paramagnetic resonance spin capture test method is as follows: DMPO is used as a spin capture agent, 2 μL of 3M DMPO is added to 60 μL of DA-R mixed aqueous solution with different pH values, and the solution is mixed evenly by vortexing. The mixed solution is transferred to an electron paramagnetic resonance quartz capillary (inner diameter 1 mm, outer diameter 1.55 mm) and sealed with a sealant at one end, the capillary is inserted into a paramagnetic tube with a diameter of 4 mm, and then placed in the electron paramagnetic resonance cavity for electron paramagnetic resonance detection. The electron paramagnetic resonance parameters are set as follows: microwave frequency is 9.83 GHz, modulation frequency is 100 kHz, modulation amplitude is 1.0 G, receiver gain is 10 dB, center field is 3505 G, scan width is 100 G, time constant is 5.12 ms, scan time is 60 s, and microwave power is 20 mW.

[0063] The generation of hydroxyl radicals in the DA-R mixed aqueous solution under visible light irradiation was further confirmed by the electron paramagnetic resonance secondary spin capture method. The specific operation method is generally the same as the electron paramagnetic resonance spin capture test method, except that the electron paramagnetic resonance spin capture detection was performed after adding 5% hydroxyl radical scavenger DMSO to the DA-R mixed aqueous solution. The hydroxyl radicals were quantitatively analyzed using Bruker's Xenon software to obtain the absolute amount of hydroxyl radicals, recorded as M (mol / L). The absolute amount of hydroxyl radicals calculated above was compared with the absolute amount of original hydroxyl radicals obtained under the same conditions without adding DMSO to obtain the reduction in hydroxyl radicals.

[0064] Figure 4a The signal diagram of the dopamine hydrochloride-rutile titanium dioxide mixed solution through secondary spin capture in Example 1 of the present invention is shown, wherein DA-R is the original free radical capture signal diagram, and DA-R-5% DMSO is the electron paramagnetic resonance spectrum of converting part of the hydroxyl radicals into methyl radicals by adding 5% dimethyl sulfoxide (DMSO); Figure 4b The bar graph shows the concentration change of hydroxyl radicals before and after quenching some hydroxyl radicals with 5% DMSO. Figure 4a As shown in the figure, it is qualitatively demonstrated that both neutral and alkaline solutions of DA-R can generate hydroxyl radicals under visible light irradiation. Figure 4bAs shown in the figure, at pH = 10, after adding 5% hydroxyl radical scavenger DMSO, the amount of DMPO-•OH generated decreased by 1.825μM. In other neutral or alkaline pH environments, the addition of free radical scavenger DMSO can reduce the amount of DMPO-•OH generated to a certain extent. This result provides verification that DA-R mixed aqueous solution can generate hydroxyl radicals in the neutral or alkaline range and under visible light conditions.

[0065] Embodiment 2:

[0066] The preparation process of Example 2 is substantially the same as that of Example 1, except that the illumination time used in Example 2 is 10 min and the scanning time is 30 s.

[0067] Figure 5 The graph of the variation of the hydroxyl radical generation content in the DA-R aqueous solution under visible light irradiation at pH 9-11 in Example 1 of the present invention is shown. Figure 5 As shown in the figure, taking the DA-R mixed aqueous solution at pH=10 as an example, under visible light irradiation conditions, the DA-R mixed aqueous solution immediately produces a large number of hydroxyl radicals, and can continue to produce hydroxyl radicals for at least 1 hour. The amount of hydroxyl radicals generated reaches the highest level at 660 seconds of illumination, which is about 7.7μM. Figure 6 The curves of the hydroxyl radical generation content in the DA-R aqueous solution at different illumination times are shown in Examples 1 and 2 of the present invention. When the visible light source is turned off after 10 minutes of illumination, the generation of hydroxyl radicals at 60 minutes decreases by 1-2 μM compared with the illumination for 60 minutes, indicating that a higher yield of hydroxyl radicals can be achieved by illumination for 10-12 minutes.

[0068] Comparative Example 1:

[0069] The preparation process of this comparative example 1 is substantially the same as that of the example 1, except that the photocatalyst used in this comparative example 1 is anatase titanium dioxide. Figure 7 The magnetic field response spectrum of spin capture of dopamine hydrochloride-anatase titanium dioxide (DA-A) under visible light irradiation of Comparative Example 1 of the present invention is shown. Figure 7 As shown, it can be seen that when the photocatalyst is anatase titanium dioxide, its response effect is not obvious.

[0070] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing hydroxyl radicals under visible light irradiation, comprising: Dissolving dopamine compounds and rutile titanium dioxide in water to prepare a mixed solution; Under light-proof conditions, adjusting the pH of the mixed solution to ≥7; The mixed solution after adjusting the pH is placed under light of a preset wavelength for photochemical reaction to generate hydroxyl radicals.

2. The preparation method according to claim 1, wherein The dopamine compound includes dopamine hydrochloride or dopamine.

3. The preparation method according to claim 1, wherein The step of dissolving the dopamine compound and rutile titanium dioxide in water to prepare a mixed solution comprises: dissolving a dopamine compound in water to obtain a dopamine solution; dissolving rutile titanium dioxide in water to obtain a rutile titanium dioxide solution; The dopamine solution and the rutile titanium dioxide solution are mixed to form a mixed solution.

4. The preparation method according to claim 2, wherein The concentration of dopamine in the mixed solution is 0.5-10 mM, and the concentration of rutile titanium dioxide in the mixed solution is 0.05-1.0 g / L.

5. The preparation method according to claim 1, wherein The pH of the mixed solution is between 9 and 11.

6. The preparation method according to claim 1, wherein The irradiation time under the preset wavelength light is 1 to 60 minutes.

7. The preparation method according to claim 1, wherein The wavelength range of the preset wavelength is >300nm.

8. The preparation method according to claim 1, wherein The wavelength range of the preset wavelength includes 400~1000nm.

9. Use of hydroxyl radicals prepared by the preparation method according to any one of claims 1 to 8 in sterilization and disinfection and degradation and removal of pesticide residues.

Images