Iron-based cathode material for wastewater treatment and preparation method and application thereof

Abstract

The application discloses an iron-based cathode material for wastewater treatment and a preparation method and application thereof. The application proposes a strategy of cation layer regulating a cathode surface / peroxysulfate in view of the problem that the peroxysulfate is inhibited in cathode activation due to electrostatic repulsion between the cathode surface and the peroxysulfate in a cathode-activated peroxysulfate reaction system. A metal cation layer is deposited on the cathode surface, an interface with a positive Zeta potential appears, the electrostatic repulsion of the interface is effectively weakened, the interface aggregation effect of the peroxysulfate on the cathode is significantly strengthened, and the activation of the peroxysulfate is improved. The iron-based cathode material can be used for electrochemical activation of the peroxysulfate to degrade organic matters in water, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and in particular relates to an iron-based cathode material for wastewater treatment, its preparation method, and its application. Background Technology

[0002] With the acceleration of industrialization and rapid population growth, wastewater containing toxic and harmful organic compounds has become a major challenge to environmental protection, restricting the sustainable development of human society and becoming a research hotspot in various countries. These organic compounds, such as pharmaceuticals, dyes, pesticides, and microplastics, are not only widely present in surface water and groundwater, but also possess strong biotoxicity, environmental persistence, and bioaccumulation, posing a potential threat to the ecological environment and human health. Therefore, the resource utilization of wastewater plays a crucial role in alleviating water scarcity.

[0003] In existing technologies, flocculation sedimentation and membrane filtration are common methods for removing organic matter from water. However, these methods only separate the organic matter, and further degradation of organic matter existing in the solid phase is still required. Biodegradation and advanced oxidation methods are often used for the degradation of organic matter, but biodegradation methods have disadvantages such as long treatment time and low degradation efficiency, while advanced oxidation methods have relatively better degradation effects. Among them, the electrochemically activated persulfate method has good practicality.

[0004] HSO5 in the electrochemically activated persulfate process - / S2O8 2- Ions gain electrons at the cathode and are reduced to generate reactive oxygen species (ROS), such as sulfate radicals (SO4·4·4). - The reactive oxygen species (ROS) react with organic matter to form free radicals such as hydroxyl radicals (·OH), which then decompose the organic matter into smaller molecules or completely mineralize it into CO2 and H2O. The electrochemically activated persulfate (PS) method for degrading organic pollutants faces the challenge of slow interfacial mass transfer. In the cathode region, the cathode surface carries a negative charge, and PS reacts in the electrolyte as negatively charged HSO5. - / S2O8 2- Due to the inherent properties of PS, electrostatic repulsion occurs between the two charges under the interaction of like charges, making it difficult for ions to effectively adsorb onto the cathode surface. This affects the activation of PS and consequently the degradation rate of organic matter. Therefore, there is an urgent need for an electrode material that enhances the aggregation effect of PS at the cathode interface. Summary of the Invention

[0005] To address at least some of the technical problems in the prior art, the present invention provides an iron-based cathode material for wastewater treatment, its preparation method, and its applications. Specifically, the present invention includes the following:

[0006] A first aspect of the present invention provides a method for preparing an iron-based cathode material for wastewater treatment, comprising the following steps:

[0007] (1) The carbon cloth was surface functionalized using a strong oxidizing solution to obtain pretreated carbon cloth;

[0008] (2) Using the first deposition solution, iron oxide is electrodeposited on the pretreated carbon cloth to obtain a FeOOH electrode;

[0009] (3) Using a second deposition solution, metal cations are electrodeposited on the FeOOH electrode to obtain an M-FeOOH electrode, wherein M is a metal cation, and the first deposition solution and the second deposition solution are different.

[0010] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, in step (1), the strong oxidizing solution includes at least one of concentrated nitric acid, concentrated sulfuric acid, sodium hypochlorite solution and potassium permanganate solution.

[0011] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, in step (2), the first deposition liquid includes at least one of ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate, ferric nitrate, and ferrous nitrate.

[0012] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, in step (3), the metal cation includes high-valence metal cations.

[0013] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, the metal cation includes Zr. 4+ 、Nd 3+ La 3+ Ce 3+ Mg 2+ Cu 2+ Zn 2+ Mn 2+ Na + and K + At least one of them.

[0014] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, in step (3), the second deposition solution includes a compound containing the metal cation.

[0015] In some embodiments, according to the method for preparing iron-based cathode materials for wastewater treatment according to the present invention, the electrodeposition current density is 5-15 mA / cm². 2The electrodeposition time is 10-30 min.

[0016] In a second aspect, the present invention provides an iron-based cathode material obtained by the preparation method described in the first aspect of the present invention.

[0017] A third aspect of the present invention provides the application of the iron-based cathode material according to the second aspect of the present invention in the electrochemically activated degradation of organic matter in water by persulfate.

[0018] In some embodiments, according to the application described in the invention, the organic compound includes at least one of phenol, p-chlorophenol, sulfadiazine, sulfamethoxazole, and sulfamethadiazole.

[0019] This invention addresses the problem of electrostatic repulsion between the cathode surface and polysaccharide (PS) inhibiting PS activation in cathode-activated persulfate reaction systems. It proposes a strategy of regulating the cathode surface / PS solution using a cation layer. By depositing a metal cation layer on the cathode surface, an interface with a positive zeta potential is created, effectively weakening the interfacial electrostatic repulsion and significantly enhancing the interfacial aggregation effect of PS at the cathode. This promotes the activation of persulfate and the generation of reactive oxygen species, thereby facilitating the effective degradation of organic matter in water. Furthermore, the iron-based cathode material of this invention has advantages such as simple preparation process, high activity, large specific surface area, and low toxicity, showing broad application prospects and promoting research and experimental development in environmental protection technologies. Attached Figure Description

[0020] Figure 1 The stability of the iron-based cathode material of the present invention for the degradation of phenol is demonstrated.

[0021] Figure 2 The zero-charge potential of the iron-based cathode material of the present invention is shown in multiple degradation experiments.

[0022] Figure 3 The zero-charge potential of different metal cation layer electrode materials is shown.

[0023] Figure 4 The stability of the electrode material prepared by the self-assembly method for phenol degradation is shown.

[0024] Figure 5 The zero-charge potential of electrode materials obtained by different methods is shown.

[0025] Figure 6 The degradation performance of electrode materials obtained by different deposition methods on various pollutants is shown. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that the upper and lower limits of the range and each intermediate value between them are specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] [Preparation Method]

[0030] One aspect of the present invention provides a method for preparing an iron-based cathode material, comprising steps (1)-(3), which will be described in detail below.

[0031] Step (1) of this invention involves surface functionalizing carbon cloth with a strong oxidizing solution to obtain pretreated carbon cloth. The source of the carbon cloth is not particularly limited and can be a commercially available product; the strong oxidizing solution is not particularly limited, and examples include, but are not limited to, concentrated nitric acid, concentrated sulfuric acid, sodium hypochlorite solution, and potassium permanganate solution. In a preferred embodiment, the strong oxidizing solution is 65% concentrated nitric acid. It is understood that the carbon cloth can be washed or dried before or after surface functionalization; the washing liquid is not particularly limited, and examples include, but are not limited to, acetone, ethanol, and deionized water.

[0032] Step (2) of the present invention is to electrodeposit iron oxide on the pretreated carbon cloth using a first deposition solution to obtain a FeOOH electrode. The first deposition solution includes an iron-containing compound, which is not particularly limited, and examples include, but are not limited to, ferric chloride, ferrous chloride, ferrous sulfate, ferrous sulfate, ferrous nitrate, ferrous nitrate, etc.

[0033] Step (3) of the present invention is to electrodeposit metal cations on the FeOOH electrode using a second deposition solution to obtain an M-FeOOH electrode, wherein M is a metal cation, and the metal cation includes high-valence metal cations. The high-valence metal cations are not particularly limited, and examples include, but are not limited to, Zr. 4+ 、Nd 3+ La 3+ Ce 3+ The second deposition solution comprises a compound of the metal cation, examples of which include, but are not limited to, ZrOCl2, NdCl3, LaCl3, La(NO3)3, CeCl3, etc. In a preferred embodiment, the metal cation is Zr. 4+ The second deposition solution is a solution containing ZrOCl2.

[0034] To enhance the interfacial aggregation effect of persulfate on the cathode using iron-based cathode materials, the electrodeposition current density and time of this invention can be controlled within a suitable range. In this invention, the electrodeposition current density is 5-15 mA / cm². 2 Preferably 6-14 mA / cm 2 It is also preferred to have a strength of 7-13 mA / cm 2 More preferably 8-12 mA / cm 2 For example, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12 mA / cm 2 The electrodeposition time is 5-30 min, preferably 5-25 min, even more preferably 5-20 min, and more preferably 5-15 min, for example 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 min. In a preferred embodiment, the electrodeposition current density is 10 mA / cm². 2 The electrodeposition time was 10 min.

[0035] In a preferred embodiment, the working electrode, counter electrode, and reference electrode of the electrodeposition are the pretreated carbon cloth, platinum sheet, and Ag / AgCl electrode, respectively.

[0036] [Iron-based cathode materials]

[0037] In one aspect, the present invention provides an iron-based cathode material obtained by the preparation method described herein.

[0038] In a preferred embodiment, the iron-based cathode material of the present invention has a surface charge of not less than +0.13 V, a degradation rate of not less than 94.93% for sulfadiazine (SMT), a degradation rate of not less than 95.67% for sulfamethoxazole (SMX), a degradation rate of not less than 99.01% for sulfadiazine (SDZ), a degradation rate of not less than 98.64% for 4-chlorophenol (4-CP), and a degradation rate of 100% for phenol. After three organic degradation processes, the degradation performance for phenol remains above 95%.

[0039] [application]

[0040] One aspect of the present invention provides the application of the iron-based cathode material described herein in the electrochemical activation of persulfate degradation of organic matter in water. The organic matter is not particularly limited, and examples include, but are not limited to, phenol, p-chlorophenol, sulfadiazine, sulfamethoxazole, and sulfamethadiazole.

[0041] In a preferred embodiment, the cathode of the organic degradation system is the iron-based cathode material described in this invention, the anode is a PbO2 electrode, and the current density is 2-10 mA / cm². 2 The persulfate concentration is 0-2.5 mmol / L.

[0042] Example

[0043] This embodiment illustrates the preparation of Zr using a two-step electrodeposition method. 4+ The process of the FeOOH electrode.

[0044] 1. Preparation method

[0045] (1) The carbon cloth was ultrasonically cleaned in acetone and anhydrous ethanol for 10-30 min each to remove surface impurities, and then thoroughly washed with deionized water. The carbon cloth was refluxed in concentrated HNO3 (65%) at 100℃ for 5 h for surface functionalization treatment. Finally, the carbon cloth was washed with deionized water and dried at 80-120℃ to obtain the pretreated carbon cloth.

[0046] (2) Zr was obtained by electrodeposition on the pretreated carbon cloth using a two-step electrodeposition method. 4+ Specifically, FeOOH was deposited using carbon cloth, platinum sheet, and Ag / AgCl as the working, counter, and reference electrodes, respectively. The electrolyte was Na₂SO₄, and the deposition solution was an aqueous solution of FeCl₂·4H₂O. The deposition was carried out at a current density of 10 mA / cm². 2 The deposition time was 10 min. The electrode was washed with deionized water and dried at 105 °C to obtain the FeOOH electrode. The FeOOH electrode was then placed in an aqueous solution of ZrOCl2·8H2O, and the deposition current density was 10 mA / cm². 2The deposition time was 10 min. The electrode was washed with deionized water and dried at 105 °C to obtain Zr. 4+ -FeOOH electrode.

[0047] 2. Electrode stability determination

[0048] 2.1 Measurement Method

[0049] The Zr 4+ Stability testing of degraded contaminants was conducted using a FeOOH electrode (two-step electrodeposition). The contaminant was phenol at a concentration of 20 mg / L, PS at a concentration of 2 mmol / L, and the current density was 10 mA / cm². 2 The reaction time was 30 min. After the reaction, the electrode was rinsed with deionized water, dried at 105℃, and subjected to multiple pollutant degradation experiments. The surface charge of the electrode after the reaction was also tested.

[0050] 2.2 Measurement Results

[0051] The results are as follows Figure 1 and Figure 2 As shown, Zr 4+ Three organic degradation experiments were conducted using a -FeOOH electrode (two-step electrodeposition). The degradation performance for phenol was consistently above 95%, and the electrode surface charge remained above +0.10 V. This demonstrates that Zr... 4+ -FeOOH (two-step electrodeposition) has good stability.

[0052] Comparative Example 1

[0053] The following illustrates the preparation of X by electrodeposition and self-assembly. + The process of the FeOOH electrode.

[0054] 1. Preparation method

[0055] (1) The carbon cloth was ultrasonically cleaned in acetone and anhydrous ethanol for 10-30 min each to remove surface impurities, and then thoroughly washed with deionized water. The carbon cloth was refluxed in concentrated HNO3 (65%) at 100℃ for 5 h for surface functionalization treatment. Finally, the carbon cloth was washed with deionized water and dried at 80-120℃ to obtain the pretreated carbon cloth.

[0056] (2) An FeOOH electrode was electrodeposited on the pretreated carbon cloth (method as in the example). Using a self-assembly method, the FeOOH electrode was immersed in solutions of various metal cations to adsorb the metal cation layer, thus preparing X. + -FeOOH electrode (X) + Zr 4+ 、Nd 3+ La 3+Ce 3+ Mg 2+ Cu 2+ Zn 2+ Mn 2+ Na + and K + ).

[0057] 2. Performance Testing

[0058] 2.1 Surface Electrode Potential

[0059] Determine different X + The surface electrode potential of the FeOOH electrode material is shown in the following results. Figure 3 As shown, the surface electrode potentials from largest to smallest are: Zr 4+ >Nd 3+ >La 3+ >Ce 3+ >Mg 2+ >Cu 2+ >Zn 2+ >Mn 2+ Na + >K + .

[0060] 2.2 Electrode Stability

[0061] The Zr prepared in this comparative example was determined. 4+ The stability of the FeOOH electrode is shown in the following results. Figure 4 As shown, the second application only achieved 50% phenol degradation, indicating that the Zr prepared using this comparative method... 4+ The stability of the FeOOH electrode needs further improvement.

[0062] Comparative Example 2

[0063] The following illustrates the preparation of Zr using a one-step electrodeposition method. 4+ The process of the FeOOH electrode.

[0064] 1. Preparation method

[0065] (1) The carbon cloth was ultrasonically cleaned in acetone and anhydrous ethanol for 10-30 min each to remove surface impurities, and then thoroughly washed with deionized water. The carbon cloth was refluxed in concentrated HNO3 (65%) at 100℃ for 5 h for surface functionalization treatment. Finally, the carbon cloth was washed with deionized water and dried at 80-120℃ to obtain the pretreated carbon cloth.

[0066] (2) Zr was prepared on pretreated carbon cloth by a one-step electrodeposition method. 4+The FeOOH electrode, specifically, uses carbon cloth, platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. The electrolyte is Na2SO4, and the deposition solution is a mixed solution of FeCl2·H2O and ZrOCl2·6H2O. The deposition current density is 10 mA / cm². 2 The deposition time was 20 min. The electrode was washed with deionized water and dried at 105 °C for later use to prepare Zr. 4+ -FeOOH electrode.

[0067] 2. Performance Testing

[0068] 2.1 Surface Charge Measurement

[0069] The surface charge of the electrodes in the examples and the comparative example was measured using the zero-charge potential method, and the results are as follows: Figure 5 As shown, the zero-charge potential indicates that the surface charge of the FeOOH electrode is -0.14 V, and the Zr... 4+ The surface charge of the FeOOH electrode (one-step electrodeposition) is +0.07 V, Zr 4+ The surface charge of the FeOOH electrode (two-step electrodeposition) is +0.13 V. Therefore, the order of surface charge magnitude is: Zr 4+ -FeOOH electrode (two-step electrodeposition) > Zr 4+ -FeOOH electrode (one-step electrodeposition) > FeOOH electrode.

[0070] 2.2 Pollutant Degradation Performance Test

[0071] The electrodes of the examples and the comparative examples were tested for contaminant degradation performance. The contaminants were phenol, p-chlorophenol (4-CP), sulfadiazine (SDZ), sulfamethoxazole (SMX), and sulfamethadiazole (SMT). The contaminant concentration was 20 mg / L, the PS concentration was 2 mmol / L, and the current density was 10 mA / cm². 2 The reaction time was 30 min. The results are as follows: Figure 6 As shown, Zr 4+ The contaminant degradation performance of the FeOOH electrode (two-step electrodeposition) is significantly better than that of Zr. 4+ -FeOOH electrode (one-step electrodeposition).

[0072] In summary, since the cathode and PS share the same charge, electrostatic repulsion exists. The electrode prepared by the two-step electrodeposition method has a more positive surface charge than the electrode prepared by the one-step electrodeposition method. This results in a stronger electrostatic attraction of the electrode surface to PS, leading to better activation of PS to generate ROS and thus more effective degradation of pollutants. Therefore, the Zr prepared in the examples... 4+-FeOOH electrode (two-step electrodeposition) has superior pollutant degradation performance.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The application of iron-based cathode materials in wastewater treatment, characterized in that, The iron-based cathode material is used to enhance the interfacial aggregation effect of persulfate at the cathode, promote persulfate activation, and thereby degrade organic matter in wastewater. The iron-based cathode material is prepared by the following method: (1) The carbon cloth was surface functionalized using a strong oxidizing solution to obtain pretreated carbon cloth; (2) Using the first deposition solution, iron oxide is electrodeposited on the pretreated carbon cloth to obtain a FeOOH electrode; (3) Using a second deposition solution, metal cations are electrodeposited on the FeOOH electrode to obtain an M-FeOOH electrode, wherein M is a metal cation, and the metal cation is Zr. 4+ 、Nd 3+ La 3+ or Ce 3+ The first sediment and the second sediment are different.

2. The application of the iron-based cathode material according to claim 1 in wastewater treatment, characterized in that, In step (1), the strong oxidizing solution includes at least one of concentrated nitric acid, concentrated sulfuric acid, sodium hypochlorite solution and potassium permanganate solution.

3. The application of the iron-based cathode material according to claim 1 in wastewater treatment, characterized in that, In step (2), the first precipitate includes at least one of ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate, ferric nitrate, and ferrous nitrate.

4. The application of the iron-based cathode material according to claim 1 in wastewater treatment, characterized in that, The current density for electrodeposition is 5-15 mA / cm². 2 The electrodeposition time is 10-30 min.

5. The application of the iron-based cathode material according to claim 1 in wastewater treatment, characterized in that, The organic compound includes at least one of phenol, p-chlorophenol, sulfadiazine, sulfamethoxazole, and sulfamethadiazole.

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