Preparation and application of FeS2@FeOOH three-dimensional particles

Abstract

The present invention relates to the field of deep treatment of industrial wastewater, and in particular to the preparation and application of FeS2@FeOOH three-dimensional particles. A certain amount of FeS2 is added to a Na2SO4 solution and hydrogen peroxide, and an electrolytic reaction is carried out in an electrolytic cell, wherein the anode is a ruthenium iridium titanium plate and the cathode plate is a carbon cloth or a gas diffusion electrode GDE, to obtain FeS2@FeOOH with a core-shell structure. The present invention can achieve deep treatment of high-salt industrial wastewater with FeS2@FeOOH three-dimensional particle electrodes. Using FeS2@FeOOH as a three-dimensional particle, the three-dimensional particle electrode can produce • OH, O2 •－ 、 1 O2, active chlorine free radicals, etc. The synergistic effect of free radicals and electron transfer on the surface of FeS2@FeOOH material is used to achieve efficient removal of TOC and TN.

Description

Technical Field

[0001] The present invention relates to the field of advanced treatment of industrial wastewater, and in particular to the preparation and application of FeS2@FeOOH three-dimensional particles. Background Art

[0002] Biochemical treatment of industrial wastewater aims to reduce total organic carbon (TOC) and total nitrogen (TN). However, after conventional secondary biochemical treatment, the effluent still contains a large amount of toxic, hazardous, and recalcitrant organic pollutants, as well as high suspended solids, color, and salinity. The ubiquitous presence of TOC and TN in industrial biochemical effluents prevents treated wastewater from meeting discharge standards for coking wastewater and contaminates subsequent membrane treatment processes. In recent years, water purification processes based on electrocatalytic oxidation have garnered worldwide attention due to their strong oxidation capacity, simple operation, and lack of secondary pollution. However, drawbacks of traditional electrochemical processes, such as low current efficiency, mass transfer limitations, and high costs, have limited their practical application. The three-dimensional electrode method, which incorporates granular electrodes between the anode and cathode, improves solution conductivity and accelerates mass transfer within the reactor. Furthermore, by generating and utilizing a range of strong oxidants (·OH, ·O2, etc.), it surpasses traditional electrocatalytic methods in terms of pollutant removal efficiency. These advantages of three-dimensional particle electrodes offer a superior solution for removing organic pollutants from wastewater.

[0003] Patent CN110064408B invented an α-crystalline iron oxyhydroxide catalyst loaded with iron sulfide, which was prepared by hydrothermal method to form a doped material for photocatalytic degradation of organic matter and heavy metals. The FeS2 in this doped material can be used as a catalyst or particle electrode to effectively remove difficult-to-degrade organic pollutants in wastewater, but the reacted FeS2 will mostly dissolve in the electrolyte, releasing Fe 3+ and SO4 2- , thus generating sludge pollution. Summary of the Invention

[0004] In order to solve the problem that FeS2 as a catalyst or particle electrode is easily soluble in the electrolyte, generates sludge pollution, and cannot achieve the denitrification function, the present invention provides a preparation and application of FeS2@FeOOH three-dimensional particles.

[0005] This patented method involves treating FeS2 to create a stable FeS2@FeOOH material, forming a three-dimensional particle electrode system. This three-dimensional system achieves efficient removal of TOC and TN. This patented method utilizes an electrochemical in-situ core-shell structure to prepare the FeS2@FeOOH. The mild reaction conditions make it suitable for large-scale production, resulting in a stable material specifically designed for TOC and TN removal.

[0006] The present invention is achieved through the following technical solution: a method for preparing FeS2@FeOOH three-dimensional particles, comprising the following steps:

[0007] A certain amount of FeS2 is added to Na2SO4 solution and hydrogen peroxide, and electrolyzed in an electrolytic cell, where the anode is a ruthenium-iridium-titanium plate and the cathode is a carbon cloth or a gas diffusion electrode GDE, to produce FeS2@FeOOH with a core-shell structure.

[0008] As a further improvement of the technical solution of the present invention, in the electrolytic cell, the amount of FeS2 added is 3 g, the amount of Na2SO4 solution added is 200 mL, the amount of hydrogen peroxide added is 200 μL, the concentration of Na2SO4 solution is 1.5 g / L, and the concentration of hydrogen peroxide is 0.4 g / L.

[0009] As a further improvement of the technical solution of the present invention, the current density of the electrolysis reaction is 25 mA / cm 2 .

[0010] The present invention further provides an application of FeS2@FeOOH with a core-shell structure prepared by a method for preparing FeS2@FeOOH three-dimensional particles in the treatment of high-salt wastewater.

[0011] As a further improvement of the above-mentioned application technical solution, the concentration of NaCl in the high-salt wastewater is not less than 1000 mg / L.

[0012] As a further improvement of the above-mentioned application technical solution, the core-shell structured FeS2@FeOOH adopts the electrolytic treatment method for high-salt wastewater in the treatment of high-salt wastewater.

[0013] As a further improvement of the above-mentioned application technology solution, when electrolyzing high-salt wastewater, the anode used is an iridium-ruthenium-coated titanium plate, the cathode used is a carbon cloth or a gas diffusion electrode GDE, the dosage of the core-shell structure FeS2@FeOOH is 10-20 mg / L, and the current density is 10-30 mA / cm 2 .

[0014] As a further improvement of the above-mentioned application technology solution, the pH range of the high-salt wastewater is 3.0-10, the initial concentration of Na2SO4 is not less than 1000 mg / L, the COD concentration of organic pollutants is 0-200 mg / L, and the NO3 - The concentration is 0-50 mg / L.

[0015] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0016] 1) The present invention prepares FeS2@FeOOH three-dimensional particles with core-shell structure and stable material, which solves the problems of easy leaching of iron metal ions and loss of active sulfur in the prior art, and realizes Fe 2+ / Fe 3+ effective circulation.

[0017] 2) The present invention can realize the deep treatment of high-salt industrial wastewater with FeS2@FeOOH three-dimensional particle electrode. FeS2@FeOOH is used as a three-dimensional particle. The three-dimensional particle electrode can produce • OH, O2 •－ 、 1 O2, active chlorine radicals, etc. The synergistic effect of free radicals and electron transfer on the FeS2@FeOOH surface was used to achieve efficient removal of TOC and TN. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 TEM diagram of the core-shell structured FeS2@FeOOH prepared in Example 1. TEM EDS mapping confirmed that a 10 nm thick oxide was formed on the surface of the particle electrode, generating a material with a core-shell structure.

[0021] Figure 2 The FTIR spectra of FeS2 and the core-shell structure FeS2@FeOOH prepared in Example 1 show a peak at 3371 cm⁻¹, which is characteristic of the –OH group in the carboxyl group. Positions at approximately 2972 ​​cm⁻¹ and 1385 cm⁻¹ correspond to the stretching vibration of the CO bond and the stretching vibration of the CO bond, respectively. FTIR analysis reveals the presence of various functional groups on the surfaces of both pristine and used FeS2, which serve as important active catalytic sites for the degradation reaction in the particle electrode. The appearance of the –OH peak after the reaction indicates that hydroxyl radicals were generated during the reaction and participated in the degradation process.

[0022] Figure 3The XPS spectra of FeS2 and the core-shell structure FeS2@FeOOH prepared in Example 1 (ad is FeS2, eeg is FeS2@FeOOH). The presence of S, Fe, and O can be seen from a and e. In the S 2p spectrum (Figure b), the binding energy peaks of 162.7 and 161.9 eV belong to the S in FeS2. 2- The binding energy peak of 168.9 eV corresponds to SO4 2- In FeS2@FeOOH, S 2- The characteristic peaks of SO4 2- The characteristic peak of FeS2 at 163.9 eV increases after the reaction, indicating that more hydrophobic substances such as S n 2- The accumulation of n 2- It is bound to FeS2 through covalent or ionic bonds and is therefore retained on the surface of FeS2. The two peaks at 161.3 and 161.9 eV correspond to the disulfide of the reaction. The reason is that the SS bond is not as strong as the Fe-S bond, which makes the SS bond easier to break in the FeS2 lattice. The Fe2p spectrum of FeS2 shows a peak at a binding energy of 707.1 eV, which corresponds to Fe(II)-S in FeS2. The obvious peaks at 711.5 eV and 720.4 eV belong to Fe 3+ 2p3 / 2 and Fe 3+ 2p1 / 2, which means Fe 3+ The difference in peaks at 711.5 eV between FeOOH, FeS2, and FeS2@FeOOH is attributed to Fe-O and Fe-OOH bonds, further confirming the formation of Fe2O3 and Fe-OOH amorphous phases. Furthermore, in the O 1s region, two main peaks are observed for FeS2@FeOOH at 532 and 533 eV, corresponding to Fe-O-Fe and Fe-OH bonds, respectively. The absence of a peak at 530 eV indicates the absence of Fe2O3 and suggests the accumulation of OOH bonds.

[0023] Figure 4 Schematic diagram of the treatment results of Experimental Example 1. The results show that the amount of iron component dissolved during the reaction is negligible, which further confirms the excellent reusability of the constructed three-dimensional electrode system.

[0024] Figure 5 Schematic diagram of the processing results of Experimental Example 2. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] The specific embodiments of the present invention are described in detail below. Example 1

[0028] A method for preparing three-dimensional FeS2@FeOOH particles comprises the following steps:

[0029] A certain amount of FeS2 was added to a Na2SO4 solution and hydrogen peroxide, and then electrolyzed in an electrolytic cell with a ruthenium-iridium-titanium anode and a carbon cloth cathode to produce a core-shell FeS2@FeOOH structure. The cell contained 3g of FeS2, 200mL of Na2SO4 solution, and 200μL of hydrogen peroxide, achieving a Na2SO4 solution concentration of 1.5g / L and a hydrogen peroxide concentration of 0.4g / L. Example 2

[0030] 1. Material characterization

[0031] Specific results such as Figures 1 to 3 shown.

[0032] 2. Test Example 1

[0033] The effluent from the secondary sedimentation tank after biochemical treatment of coking wastewater (high-salt wastewater) was treated, with a ruthenium-iridium-titanium plate as the anode and a carbon cloth electrode as the cathode. The distance between the electrode plates was 1 cm, the dosage of core-shell structured FeS2@FeOOH was 15 g / L, and the current density was 20 mA / cm 2 ; The high-salt wastewater components are shown in the initial values ​​in the following table. After testing, the content of iron components in the simulated wastewater after 6 hours of reaction changed as follows Figure 4 shown.

[0034] 3. Test Example 2

[0035] The effluent from the secondary sedimentation tank after biochemical treatment of coking wastewater (high-salt wastewater) was treated, with a ruthenium-iridium-titanium plate as the anode and a carbon cloth electrode as the cathode. The distance between the electrode plates was 4 cm, the dosage of core-shell structured FeS2@FeOOH was 15 g / L, and the current density was 15 mA / cm 2 The water quality of the inlet and outlet water is shown in the following table. After testing, the reaction results are shown in Figure 5a, TOC, NO3 after 6 hours - The removal rates of -N and TN were 92.2%, 92.7% and 93.3% respectively (see the final values ​​and removal rates in the table above). Figure 5 b, after 5 tests, the removal rate still remained high.

[0036] The above description is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be included in the scope of protection of the claims.

Claims

1. A method for preparing three-dimensional FeS2@FeOOH particles, characterized in that: The steps include: A certain amount of FeS2 is added to Na2SO4 solution and hydrogen peroxide, and electrolyzed in an electrolytic cell, where the anode is a ruthenium-iridium-titanium plate and the cathode is a carbon cloth or a gas diffusion electrode GDE, to produce FeS2@FeOOH with a core-shell structure.

2. The method for preparing three-dimensional FeS2@FeOOH particles according to claim 1, characterized in that: In the electrolytic cell, the amount of FeS2 added is 3 g, the amount of Na2SO4 solution added is 200 mL, the amount of hydrogen peroxide added is 200 μL, the concentration of Na2SO4 solution is 1.5 g / L, and the concentration of hydrogen peroxide is 0.4 g / L.

3. The method for preparing three-dimensional FeS2@FeOOH particles according to claim 1, characterized in that: The current density of the electrolysis reaction is 25 mA / cm 2 .

4. Use of the core-shell structured FeS2@FeOOH prepared by the method for preparing three-dimensional FeS2@FeOOH particles according to any one of claims 1 to 3 in the treatment of high-salt wastewater.

5. The use according to claim 4, characterized in that The concentration of NaCl in the high-salt wastewater is not less than 1000 mg / L.

6. The use according to claim 5, characterized in that The core-shell structured FeS2@FeOOH adopts the electrolysis method to treat high-salinity wastewater in the treatment of high-salinity wastewater.

7. The use according to claim 6, characterized in that When electrolyzing high-salt wastewater, the anode used is an iridium-ruthenium-coated titanium plate, the cathode used is a carbon cloth or a gas diffusion electrode GDE, the dosage of the core-shell structure FeS2@FeOOH is 10-20 mg / L, and the current density is 10-30 mA / cm 2 .

8. The use according to claim 7, characterized in that The pH range of the high-salt wastewater is 3.0-10, the initial concentration of Na2SO4 is not less than 1000 mg / L, the COD concentration of organic pollutants is 0-200 mg / L, and the NO3 - The concentration is 0-50 mg / L.

Images