A reactor for synchronously generating oxidative free radicals and reduced free radicals

Abstract

The present application discloses a reactor that simultaneously generates oxidative free radicals and reduced free radicals. The reactor comprises a photoanode, a photocathode, a power supply, and a light source; the photoanode and the photocathode enclose the light source; the positive electrode of the power supply is connected to the photoanode, and the cathode of the power supply is connected to the photocathode. Compared with the traditional single-photoelectrode photoelectrochemical water treatment reactor that can only produce a single type of free radical, the reactor disclosed in the present application not only has a better light energy utilization efficiency and more outstanding catalytic performance, but also has a simple structure, low manufacturing cost, high water treatment performance, good stability, and can be widely used in water treatment engineering technology.

Description

Technical Field

[0001] The present application relates to, but is not limited to, the field of water treatment, and specifically, to, but is not limited to, a columnar dual-photoelectrode photoelectrochemical water treatment reactor that simultaneously generates oxidative free radicals and reduced free radicals. Background Art

[0002] The accelerated pace of industrialization has led to serious water pollution problems. Pollutants in water have extremely adverse effects on the ecological environment and human health, especially their biological toxicity and carcinogenicity. The current mainstream water treatment technologies mainly include flocculation, adsorption, biological methods and advanced oxidation methods. Among them, the photoelectrochemical method, one of the advanced oxidation methods, has the advantages of fast reaction rate, mild conditions, no need to add toxic chemical reagents and no secondary pollution, and is therefore popular among the public. The photoelectrochemical method is to use the photoanode to generate oxidative free radicals and the photocathode to generate reduced free radicals under light excitation, and then through a series of redox reactions between the generated oxidative free radicals and reduced free radicals and the pollutants in the water, the pollutants in the water are effectively removed. Summary of the Invention

[0003] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0004] The present application provides a reactor, which comprises a photoanode, a photocathode, a power supply and a light source; the photoanode and the photocathode surround the light source; the positive electrode of the power supply is connected to the photoanode, and the cathode of the power supply is connected to the photocathode;

[0005] In one embodiment provided in the present application, the photoanode generates oxidative free radicals; the photocathode generates reduced free radicals;

[0006] In one embodiment provided in the present application, the material of the photoanode is any one or more of TiO2, WO3, ZnO, BiVO4 and C3N4;

[0007] In one embodiment provided in the present application, the material of the photocathode is any one or more of Cu2O / Pd, CuO / Pd, CdS / Pd, ZnS / Pd and Ce2O3 / Pd.

[0008] In one embodiment provided in the present application, the light source is an ultraviolet light source;

[0009] In one embodiment provided in the present application, the wavelength of the light source is 320nm to 400nm;

[0010] In one embodiment provided in the present application, the light irradiance of the light source is 20w / m2 Up to 70w / m 2 ;

[0011] In one embodiment provided in the present application, the voltage applied by the power supply across the photoanode and the photocathode is 0.8V to 1.2V.

[0012] In one embodiment provided in the present application, the photoanode is in the shape of a semicircular tube;

[0013] In one embodiment provided in the present application, the photocathode is in the shape of a semicircular tube;

[0014] In one embodiment provided in the present application, the light source is located at the center of a circular tube formed by the photoanode and the photocathode; the photoanode and the photocathode symmetrically wrap the light source.

[0015] In one embodiment provided in the present application, the photoanode is excited by light to generate oxidative free radicals; the photocathode is excited by light to generate reduced free radicals;

[0016] Oxidative free radicals (such as hydroxyl free radicals) and reducing free radicals (such as atomic hydrogen) are simultaneously generated in the reactor.

[0017] In one embodiment provided herein, the reactor further comprises an inlet and an outlet;

[0018] The inlet is configured such that reactants to react with the oxidizing free radicals and the reducing free radicals enter the reactor through the inlet;

[0019] The outlet is configured such that a residue after reaction with the oxidizing free radicals and the reducing free radicals is discharged from the reactor through the outlet.

[0020] In yet another aspect, the present application provides use of the above reactor in water treatment.

[0021] In one embodiment provided in the present application, the reactor is a columnar dual-photoelectrode photoelectrochemical water treatment reactor that simultaneously generates oxidative free radicals and reduced free radicals.

[0022] In one embodiment provided in the present application, the water contains substances that react with the oxidative free radicals and the reduced free radicals;

[0023] In one embodiment provided herein, the substance is an organic pollutant;

[0024] In one embodiment provided herein, the substance is a phenolic pollutant;

[0025] In one embodiment provided in the present application, the substance is any one or more of phenol, chlorophenol, bisphenol A, nitrobenzene and aniline.

[0026] In one embodiment provided herein, the concentration of the substance in the water is 1 mg / L to 20 mg / L;

[0027] In one embodiment provided in the present application, the hydraulic retention time (HRT) in the water treatment reactor is 2 min to 20 min.

[0028] In one embodiment provided herein, wastewater enters a water treatment reactor through a water inlet at the lower end and, after treatment, is discharged through a water outlet at the upper end. During the treatment process, the photoanode is excited by light to produce oxidative free radicals (such as hydroxyl radicals), and the photocathode is excited by light to produce reduced free radicals (such as atomic hydrogen). The generated oxidative free radicals and reduced free radicals undergo a series of redox reactions with pollutants in the water, ultimately removing the pollutants from the water.

[0029] The beneficial effects of this application are:

[0030] The columnar dual-photoelectrode photoelectrochemical water treatment reactor provided in the present application, which can simultaneously generate oxidative free radicals and reduced free radicals, has high photoelectric conversion efficiency and high catalytic performance through the combined advantages of a semi-tubular photoanode that can generate oxidative free radicals and a semi-tubular photocathode that can generate reduced free radicals.

[0031] Compared with the traditional single-photoelectrode photoelectrochemical water treatment reactor that can only produce a single type of free radical (oxidative free radical or reduced free radical), the columnar dual-photoelectrode photoelectrochemical water treatment reactor disclosed in this application that simultaneously produces oxidative free radicals and reduced free radicals not only has better light energy utilization efficiency and more outstanding catalytic efficiency, but also the device has a simple structure, low manufacturing price, high water treatment performance, good stability, and can be widely used in water treatment engineering technology.

[0032] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purposes and other advantages of the present application can be achieved and obtained through the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0034] Figure 1Schematic diagram of the structure of a columnar dual-photoelectrode photoelectrochemical water treatment reactor designed for the present application that simultaneously produces oxidative free radicals (such as hydroxyl radicals) and reduced free radicals (such as atomic hydrogen);

[0035] Figure 2 This is a working principle diagram of the reactor described in this application;

[0036] Figure 3 A comparison chart of the light energy utilization efficiency of a columnar single photoelectrode reactor for generating oxidative free radicals, a columnar single photoelectrode reactor for generating reduced free radicals, and a columnar dual photoelectrode reactor for simultaneously generating oxidative free radicals and reduced free radicals as described in the present application; the testing method is to detect the current density output by the reactors of the embodiment of the present application and the comparative example under the same experimental conditions, and determine the respective light energy utilization efficiency by calculating the photoelectric conversion efficiency (IPCE).

[0037] Figure 4 The figure shows the comparison of the degradation efficiency of phenol pollutants by a column-type single photoelectrode reactor for generating oxidative free radicals, a column-type single photoelectrode reactor for generating reduced free radicals, and a column-type dual photoelectrode reactor for generating oxidative free radicals and reduced free radicals simultaneously as described in the present application; the test method for phenol is to use high performance liquid chromatography (HPLC, C 18 The phenol concentration was determined using a chromatographic column with a mobile phase ratio of methanol:water = 80:20, a flow rate of 1.0 mL / min, an injection volume of 20 uL, and a detection wavelength of 270 nm. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0039] The present application discloses a columnar dual-photoelectrode photoelectrochemical water treatment reactor for synchronously generating oxidative free radicals and reduced free radicals. Figure 1 As shown, the reaction device is a columnar structure as a whole, with an ultraviolet lamp placed in the center as a light source, a semi-circular tubular photoanode that can generate oxidative free radicals and a semi-circular tubular photocathode that can generate reduced free radicals are symmetrically wrapped around the outer wall of the ultraviolet lamp, the photoanode is connected to the positive pole of the DC power supply through a wire, and the photocathode is connected to the negative pole of the DC power supply through a wire, and a water outlet and a water inlet are respectively provided at the upper and lower ends of the reactor.

[0040] Wastewater (such as phenol-containing wastewater) enters the reactor through the lower inlet and is discharged through the upper outlet after treatment. During the treatment process, the photoanode is excited by light to produce oxidative free radicals (such as hydroxyl radicals), and the photocathode is excited by light to produce reduced free radicals (such as atomic hydrogen). The generated oxidative free radicals and reduced free radicals undergo a series of redox reactions with pollutants in the water (such as phenol), ultimately removing the pollutants (such as phenol) from the water.

[0041] Specifically, atomic hydrogen first electrophilically adds to the carbon atom connected to the hydroxyl group in the phenol molecule to form a critical intermediate; compared with the original phenol molecule, the electron cloud density of this critical intermediate is significantly increased, making it easier for the hydroxyl radical to be further oxidized and decomposed through nucleophilic addition. This process is based on the redox synergy of atomic hydrogen and hydroxyl radicals.

[0042] In the embodiment of the present application, the material of the photoanode may be any one or more of TiO2, WO3, ZnO, BiVO4 and C3N4;

[0043] In an embodiment of the present application, the material of the photocathode may be any one or more of Cu2O / Pd, CuO / Pd, CdS / Pd, ZnS / Pd and Ce2O3 / Pd.

[0044] Example 1

[0045] Design of a cylindrical dual-photoelectrode photoelectrochemical water treatment reactor for the simultaneous generation of oxidative and reduced radicals

[0046] The reaction device is a columnar structure as a whole, with an ultraviolet lamp placed in the center as a light source. A semicircular photoanode that can generate oxidative free radicals and a semicircular photocathode that can generate reduced free radicals are symmetrically wrapped around the outer wall of the ultraviolet lamp. The photoanode is connected to the positive pole of a DC power supply through a wire, and the photocathode is connected to the negative pole of a DC power supply through a wire. Water outlet and water inlet are respectively provided at the upper and lower ends of the reactor.

[0047] The ultraviolet light source is a UVA ultraviolet lamp with a power of 20W. The length of the ultraviolet lamp is 20cm and the diameter is 2.5cm. The wavelength of the light source is 320nm to 400nm.

[0048] The diameter of the semicircular tubular photoanode is 3 cm and the length is 20 cm; the material of the photoanode is TiO2;

[0049] The diameter of the semicircular tube photocathode is 3 cm and the length is 20 cm; the material of the photocathode is Cu2O / Pd;

[0050] The irradiation intensity of the ultraviolet lamp and the semicircular tubular photoanode is 45w / m 2 ; The reactor volume is 100mL.

[0051] Example 2

[0052] The columnar dual-photoelectrode photoelectrochemical water treatment reactor for synchronously generating oxidative free radicals and reduced free radicals provided in Example 1 was used to treat phenol-containing wastewater.

[0053] 1) Prepare phenol-containing wastewater with a concentration of 5 mg / L, and then compare and analyze the degradation efficiency of phenol pollutants by a column single photoelectrode reactor that generates oxidative free radicals, a column single photoelectrode reactor that generates reduced free radicals, and a column dual photoelectrode reactor that simultaneously generates oxidative free radicals and reduced free radicals as described in this application.

[0054] 2) The hydraulic retention time of the phenol-containing wastewater is set to 20 min, and the voltage applied by the power supply across the photoanode and the photocathode is set to 1.1 V.

[0055] 3) Wastewater (containing phenol) enters the reactor from the lower inlet and is discharged from the upper outlet after treatment. During the treatment process, the photoanode is excited by light to produce oxidative free radicals (such as hydroxyl radicals), and the photocathode is excited by light to produce reduced free radicals (such as atomic hydrogen). The generated oxidative free radicals and reduced free radicals undergo a series of redox reactions with pollutants in the water (such as phenol), ultimately removing the pollutants (such as phenol) and generating water and carbon dioxide.

[0056] The phenol removal rate of this embodiment is as follows Figure 4 shown.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 1 is that the photocathode is the same as that in Example 1, with two semicircular tubes surrounding the light source, and the photocathode material is Cu2O / Pd (the photoanode material is a material that does not participate in the reaction, and the photoanode does not block the light source from irradiating the photocathode). The other components, arrangements and parameters of the water treatment reactor of this comparative example are exactly the same as those of Example 1. The test method of Example 2 was used to test the water treatment reactor of Comparative Example 1. The phenol removal rate of Comparative Example 1 was as follows: Figure 4 shown.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 1 is that the photoanode is the same as that in Example 1, with two semicircular tubes surrounding the light source, and the photoanode material is TiO2 (the photocathode material is a material that does not participate in the reaction and the photocathode does not block the light source from irradiating the photoanode). The other components, arrangements and parameters of the water treatment reactor of this comparative example are exactly the same as those of Example 1. The water treatment reactor of this comparative example was tested using the test method of Example 2. The phenol removal rate of Comparative Example 2 is as follows: Figure 4 shown.

[0061] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application, but the scope of protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. A reactor comprising a photoanode, a photocathode, a power supply, and a light source; the photoanode is semi-circular and the photocathode is semi-circular; the light source is located at the center of the circular tube formed by the photoanode and the photocathode; the photoanode and the photocathode symmetrically surround the light source; the positive electrode of the power supply is connected to the photoanode, and the cathode of the power supply is connected to the photocathode; The light source is an ultraviolet light source; The photoanode is excited by light to generate oxidative free radicals; the photocathode is excited by light to generate reduced free radicals; and the oxidative free radicals and reduced free radicals are generated synchronously in the reactor; The material of the photoanode is any one or more of TiO2, WO3, ZnO, BiVO4 and C3N4; The material of the photocathode is Cu2O / Pd.

2. The reactor according to claim 1, wherein The wavelength of the light source is 320 nm to 400 nm; the light irradiance of the light source is 20 w / m 2 Up to 70 w / m 2 . 3 . The reactor according to claim 1 , wherein the voltage applied by the power supply across the photoanode and the photocathode is 0.8 V to 1.2 V.

4. The reactor according to any one of claims 1 to 3, wherein The reactor further comprises an inlet and an outlet; The inlet is configured such that reactants to react with the oxidizing free radicals and the reducing free radicals enter the reactor through the inlet; The outlet is configured such that a residue after reaction with the oxidizing free radicals and the reducing free radicals is discharged from the reactor through the outlet.

5. Use of the reactor according to any one of claims 1 to 4 in water treatment.

6. The use according to claim 5, wherein: The water contains organic pollutants that react with the oxidizing free radicals and reducing free radicals.

7. The use according to claim 6, wherein: The organic pollutants are phenol pollutants.

8. The use according to claim 6, wherein: The organic pollutants are any one or more of phenol, chlorophenol, bisphenol A, nitrobenzene and aniline.

9. The use according to any one of claims 6 to 8, wherein The concentration of the organic pollutants in the water is 1 mg / L to 20 mg / L.

10. The use according to claim 9, wherein: The hydraulic retention time of water in the reactor is 2 min to 20 min.

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