Method for removing halogenated acetic acid in water by using Fe@C nanomaterials
The electrochemical dehalogenation method of Fe@C nanomaterials solves the problems of high cost and secondary pollution in the existing technology, achieves efficient and low-cost removal of halogenated acetic acid, and improves the safety of drinking water.
Patent Information
- Application Number
- CN202411903477.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2044-12-23
AI Technical Summary
In the existing technology, materials such as precious metal-based catalysts, non-precious metal-based oxidants and carbon-based catalysts have problems such as high cost, harsh preparation conditions, poor catalytic performance and secondary pollution when removing halogenated acetic acid from drinking water, making it difficult to efficiently remove halogenated disinfection by-products.
Fe@C nanomaterials are used as catalysts to carry out targeted dehalogenation of halogenated organic matter at the cathode through electrochemical methods. Their magnetic properties are utilized to closely combine with the electrode, and binders are discarded to achieve efficient and low-cost removal of halogenated acetic acid. The preparation method is simple and environmentally friendly.
Fe@C nanomaterials exhibit high dehalogenation efficiency during the electrocatalytic process. The material is tightly bound to the electrode and is easy to recycle and regenerate, which reduces the content of halogenated acetic acid in drinking water and improves water quality safety.
Smart Images
Figure CN119774715B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of drinking water safety guarantee, and particularly relates to a treatment method for removing halogenated disinfection byproducts by dehalogenation of drinking water. BACKGROUND
[0002] Disinfection is an essential step for guaranteeing the safety of drinking water. The chlorination process has a history of more than 100 years, and is still widely used as a method for inactivating bacteria in drinking water worldwide. However, halogenated disinfection byproducts (X-DBPs) such as chloroform are generated in the process of chlorination, and such X-DBPs have a "three-teratogenic" effect, which reduces the safety of drinking water quality.
[0003] Halogenated acetic acids (HAAs) are a major class of disinfection byproducts with high detection frequency and concentration in drinking water after chloroform. Halogenated acetic acids have strong carcinogenicity and mutagenicity, and also have embryotoxicity, which can cause damage to immune organs and harm human health. Compared with volatile DBPs such as trihalomethane and halogenated acetonitrile, halogenated acetic acids are not volatile, and almost no removal effect is achieved in the process of household heating water. Therefore, it is of great significance to develop a convenient and efficient dehalogenation technology for halogenated disinfection byproducts for the reduction control of DBPs in drinking water. Electrochemical technology is a method suitable for household terminal drinking water treatment, and the C-Cl bond in the structure of halogenated organic matter can be broken by using cathodic reduction reaction to achieve targeted dehalogenation. In order to improve the dehalogenation effect, many studies have been devoted to the development of new catalytic cathode materials, including noble metal-based catalysts, non-noble metal-based oxidants, carbon-based catalysts and organic-inorganic hybrids. However, these materials have problems such as high cost, harsh preparation conditions, poor catalytic performance and secondary pollution. SUMMARY
[0004] In view of the problems in the prior art, the application provides a method for removing halogenated acetic acid in water by using Fe@C nanomaterials, aiming to reduce the content of disinfection byproducts in drinking water. Based on the reduction reaction mechanism of halogenated organic matter in cathodic dehalogenation degradation, a magnetic catalytic nanomaterial Fe@C with enhanced electron transfer characteristics is developed, which is used for electrochemical water treatment of halogenated organic acid dehalogenation. At the same time, a Fe@C / modified magnetic electrode material can also be prepared, which abandons the adhesion agent in the method of nanomaterial modified electrode, and can also be used for electrochemical water treatment of halogenated organic acid dehalogenation. The dehalogenation method has the characteristics of targeted dehalogenation, high dehalogenation efficiency, low cost, simple and safe preparation method and stability.
[0005] The technical scheme adopted by the present application is as follows:
[0006] A method for removing halogenated acetic acid in water by using Fe@C nanomaterials, comprising the following steps:
[0007] S1, obtaining a metal Fe organic framework material;
[0008] S2, carbonizing the metal Fe organic framework material at a high temperature of 800 DEG C in a tube furnace to obtain Fe@C nanomaterials;
[0009] S3, adding the Fe@C nanomaterials to the water to be treated in an electrolytic cell device to electrolytically dehalogenate the halogenated acetic acid.
[0010] Further, in step S1, during the preparation of the metal Fe organic framework material, terephthalic acid and ferric chloride hexahydrate are used as precursor substances, and after being added to a DMF solution, the metal Fe organic framework material is prepared by using a hydrothermal method.
[0011] Further, the molar ratio of the terephthalic acid, ferric chloride hexahydrate and DMF is 1:1:280, and the mixture is stirred at a medium temperature of 20-25 DEG C for 2h to be uniformly mixed; in the hydrothermal method, the metal Fe organic framework material is prepared by reacting in an oven at 150 DEG C for 2h.
[0012] Further, in step S2, in the high-temperature carbonization process, the temperature is raised at a rate of 5 DEG C / min under a nitrogen atmosphere, and the high-temperature reaction is carried out at 800 DEG C in a tube furnace.
[0013] Further, in step S3, the electrolytic cell device uses a steel electrode as the cathode and a graphite electrode as the anode, and an electric current density of 10-50 mA / cm 2 , preferably 50 mA / cm 2 , is applied.
[0014] Further, in step S3, the electrolytic cell device uses Fe@C / magnetic electrode as the cathode and a graphite electrode as the anode, and an electric current density of 10-50 mA / cm 2 , preferably 50 mA / cm 2 , is applied; the Fe@C nanomaterials are added in the form of Fe@C / magnetic electrode material prepared by modifying the magnetic electrode.
[0015] Further, the magnetic electrode uses a neodymium-iron-boron magnet.
[0016] Further, in the process of preparing the Fe@C / modified magnetic electrode:
[0017] 1) preparing a Fe@C nanomaterial dispersion liquid;
[0018] 2) polish the magnetic electrode with 600-1000 mesh sandpaper until no obvious dirt, then apply alumina polishing liquid to the surface thereof and polish with the sandpaper until a bright mirror surface, rinse with pure water; then sequentially place in anhydrous ethanol and pure water for ultrasonic cleaning and dry; then take the Fe@C nanomaterial dispersion liquid, drop coat on the surface of the magnetic electrode and dry to obtain a Fe@C modified magnetic electrode; preferably the mass percentage of the alumina polishing liquid is 20%; the surface of the polished magnetic electrode is easier to adsorb the Fe@C nanomaterial.
[0019] Further, in step 1), in the process of preparing the Fe@C nanomaterial dispersion liquid, the Fe@C nanomaterial is added to pure water and ultrasonically dispersed to obtain the Fe@C nanomaterial dispersion liquid.
[0020] A Fe@C / modified magnetic electrode material, the surface of the magnetic electrode is loaded with Fe@C material, and the loading amount is not more than 8 mg / cm 2 , preferably 6 mg / cm 2 .
[0021] Compared with the prior art, the beneficial effects of the present application are as follows:
[0022] Firstly, the present application provides a method for reducing and dehalogenating halogenated organic matter by using Fe@C nanomaterial, which has the characteristics of targeted dehalogenation, high dehalogenation efficiency, low cost, simple and safe preparation method, and stability.
[0023] Secondly, the present application utilizes the magnetic properties of Fe@C nanomaterial, discards the use of Nafion, polytetrafluoroethylene and other adhesives in traditional methods, and realizes the close combination of catalytic material and electrode by magnetic adsorption. During the electrochemical reaction process, the Fe@C nanomaterial does not fall off, and the material is adsorbed on the electrode surface, with a large contact interface with the aqueous solution, greatly increasing the catalytic occurrence rate. The used magnetic material can be conveniently and quickly recycled, replaced and regenerated.
[0024] Thirdly, the Fe@C nanomaterial obtained after carbonization not only has magnetism, but also has a larger specific surface area and good hydrophobicity, which improves the contact area of the catalytic reaction.
[0025] Fourthly, the preparation method of the Fe@C / modified magnetic electrode in the present application is simple and low in cost, the material is green and environmentally friendly, and there is no secondary pollution; and it is suitable for degradation of halogenated disinfection by-products in drinking water, toxicity reduction, and further improvement of drinking water quality safety.
[0026] 5. Fe@C / modified magnetic electrodes can achieve efficient electrocatalytic dehalogenation of halogenated disinfection by-products. Fe@C nanomaterials are used as catalysts to modify magnetic electrodes. During the electrolysis process, electron transfer on the magnetic electrode and the good catalytic activity of Fe@C nanomaterials form a reducing agent with dehalogenation ability, achieving CX bond cleavage and dehalogenation of halogenated disinfection by-products. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 SEM images of Fe@C nanomaterials at different magnifications of the present invention ((a) 10 μm, (b) 1 μm);
[0028] Figure 2 This is a comparison chart showing the effects of different dosing methods on trichloroacetic acid removal rates in the present invention;
[0029] Figure 3 This is a comparison diagram of the effects of different current densities on trichloroacetic acid removal rates in the present invention;
[0030] Figure 4 This is a comparison chart of the effects of different Fe@C nanomaterial loadings on trichloroacetic acid removal rates in the present invention;
[0031] Figure 5 This is a comparison diagram of the effects of different pH values on trichloroacetic acid removal rates according to the present invention;
[0032] Figure 6 This is a comparison diagram of the effects of different substrate concentrations on trichloroacetic acid removal rates of the present invention;
[0033] Figure 7 Schematic diagram of the electrocatalytic trichloroacetic acid dechlorination device of the present invention;
[0034] In the figure: 1. Power box; 2. Electrolyte; 3. Electrode slot; 4. Rotor; 5. Beaker; 6. Magnetic stirrer; 7. Magnetic electrode. DETAILED DESCRIPTION
[0035] The various exemplary embodiments of the present invention are described in detail below, with relevant diagrams attached. This detailed description should not be considered as a limitation of the present invention, but should be considered as a detailed description of certain aspects and characteristics of the present invention. In addition, the numerical range in the present invention is only for judging the optimization range of the present invention, not for limiting the range, and values outside this numerical range or other declarable values are included in the present invention. In the case, unless otherwise specified, all equipment, reagents, techniques and scientific terms used are the same as those commonly understood and used by those skilled in the art in the field to which the present invention relates, and instruments and reagents without indicating the manufacturer are also conventional products that can be purchased through general procurement channels.
[0036] Example 1:
[0037] The target of the electrocatalysis in the actual case is trichloroacetic acid, the initial concentration of the trichloroacetic acid is 100, 150, 200, 250 and 300 μg / L respectively, the room temperature is 25℃, the magnetic electrode 7 in the example is a neodymium-iron-boron strong magnetic magnet with a size of 50*50*2mm, and the ultrasonic frequency in the implementation process is 50Hz.
[0038] The embodiment provides a preparation method of Fe@C nanomaterial and an electrolytic dehalogenation water treatment method for trichloroacetic acid, and specifically comprises the following steps:
[0039] S1: 3mM FeCl3·6H2O, 3mM terephthalic acid and 65mL DMF are mixed and stirred for two hours, then the obtained mixed solution is poured into a lining in a reaction kettle, and constant temperature reaction is carried out at 150℃ in an oven for 15h; after reaction, the red-brown product at the bottom is obtained through centrifugation, and is cleaned with DMF and anhydrous ethanol through ultrasonic cleaning; specifically, the red-brown product is added into a DMF solution, cleaned through ultrasonic cleaning and then centrifuged, and the upper DMF solution is poured out, and the operation is repeated twice; the red-brown product is added into an anhydrous ethanol solution, cleaned through ultrasonic cleaning and then centrifuged, and the upper anhydrous ethanol solution is poured out, and the operation is repeated twice, centrifugation is carried out at 4000rpm for 10min, the ultrasonic time is 30min, and the DMF solution and the anhydrous ethanol solution are 50mL; finally, the metal Fe organic framework material is obtained through drying in a vacuum oven at 60℃ for 12h.
[0040] S2: the metal Fe organic framework material prepared is carbonized under nitrogen condition to obtain Fe@C nanomaterial, wherein the rate of temperature rise is 5℃ / min, and constant temperature reaction is carried out at 800℃ in a tube furnace for 2h. The scanning electron microscope graph of the Fe@C nanomaterial is shown in FIG. 1.
[0041] S3: a Fe@C nanomaterial dispersion liquid is prepared. 200mg Fe@C nanomaterial is dispersed in 10.0mL pure water under the condition of an ultrasonic frequency of 50Hz for 30min to obtain a Fe@C nanomaterial dispersion liquid with a concentration of 20mg / mL.
[0042] S4: a Fe@C / modified magnetic electrode is prepared. The magnetic electrode is polished smooth with 800-mesh sandpaper, then 20wt% alumina polishing liquid is coated on the surface and polished until shiny, and then washed with pure water; then the magnetic electrode is placed in anhydrous ethanol and ultrasonically cleaned for 20min, then placed in pure water and ultrasonically cleaned for 20min, washed with pure water and naturally dried. The Fe@C nanomaterial dispersion liquid is sucked by a syringe and uniformly dropped on the surface of the magnetic electrode, and then naturally dried to obtain a Fe@C / modified magnetic electrode. The loading amount of the Fe@C nanomaterial on the modified electrode is 4mg / cm 2 .
[0043] S5: Preparation of electrolytic cell device; power supply box 1 provides power to the cathode and anode, 2L beaker 5 is used as electrolytic cell, Fe@C / modified magnetic electrode is used as cathode, graphite electrode is used as anode, electrodes are fixed by electrode clamping groove 3, the distance between electrodes is 30mm, electrode clamping groove 3 is naturally sunk at the bottom of the cell. Another rotor 4 is placed at the bottom of the cell, and continuous stirring is achieved by magnetic stirrer 6, the rotating speed is 150rpm, so that the reaction in the electrolytic cell is uniform. The electrolytic cell is wrapped with tin foil to avoid light. The electrolytic cell device is as shown in Figure 7
[0044] S6: Preparation of 1L electrolyte with initial concentration of 100, 150, 200, 250 and 300μg / L of trichloroacetic acid, adjusting the pH of the solution to 7, the current density is 50mA / cm 2 Two 30mL samples are taken at 0, 1, 2, 4, 6 and 8h after power on, respectively, to obtain two groups of parallel samples, and the concentration of trichloroacetic acid in the samples is determined by GC-ECD.
[0045] When the initial concentration of trichloroacetic acid is 300μg / L, the removal rate of trichloroacetic acid is 84.0% after 8h of electrolysis, when the substrate concentration is 250, 200 and 150μg / L, the removal rates of trichloroacetic acid after 8h of electrolysis are 87.6%, 96.0% and 97.3%, respectively. When the substrate concentration is 100μg / L, the removal rate of trichloroacetic acid reaches 98.1% after 8h of electrolysis. The change of trichloroacetic acid concentration conforms to the first-order reaction kinetics, and the dechlorination effect of different initial concentrations of trichloroacetic acid with time is as shown in Figure 6
[0046] Example 2:
[0047] On the basis of Example 1, the dechlorination reaction of trichloroacetic acid by different dosing methods was studied. The dosing methods were direct dosing without electrolysis (DCWE), direct dosing with electrolysis (DCE), electrolysis with modified magnetic electrode (MMEE), electrolysis with magnetic electrode without dosing (MEWE), and electrolysis with steel electrode without dosing (SEWE). Among them, DCWE was to directly add Fe@C nanomaterials into the trichloroacetic acid solution, and the electrolytic cell device was not powered on; DCE was to directly add Fe@C nanomaterials into the trichloroacetic acid solution, and to electrolyze with steel electrode as cathode and graphite electrode as anode; MMEE was to electrolyze with Fe@C / modified magnetic electrode as cathode and graphite electrode as anode; MEWE was to electrolyze with unmodified magnetic electrode as cathode and graphite electrode as anode; SEWE was to electrolyze with steel electrode as cathode and graphite electrode as anode. The initial concentration of trichloroacetic acid was 200 μg / L. After 8 hours of electrolysis, the removal rates of trichloroacetic acid by DCWE, DCE, MMEE, MEWE and SEWE were 3.4%, 90.4%, 96.0%, 76.6% and 75.7%, respectively. The effects of different dosing methods on the removal rate of trichloroacetic acid are shown in Figure 2 .
[0048] Example 3
[0049] On the basis of Example 1, the effects of different current densities on the removal rate of trichloroacetic acid were investigated. The initial concentration of trichloroacetic acid was 200 μg / L, and the current densities were 10, 20, 30, 40 and 50 mA / cm 2 , respectively. After 8 hours of electrolysis, the removal rates of trichloroacetic acid were 52.5%, 75.4%, 88.0%, 90.2% and 96.0%, respectively. The removal effect increased with the increase of current density. The experimental results are shown in Figure 3 .
[0050] Example 4
[0051] On the basis of Example 1, the loading amounts of Fe@C nanomaterials on the composite electrode were changed to 0, 2, 4, 6 and 8 mg / cm 2 , respectively. The initial concentration of trichloroacetic acid was 200 μg / L, the current density was 50 mA / cm 2 , and the solution pH was 7. When the loading amount was 6 mg / cm 2 , the removal rate could reach the highest of 97.5%, which was higher than that when the loading amount was 8 mg / cm 2 (95.2%). When the loading amounts were 0, 2 and 4 mg / cm 2 , the removal rates were 85.0%, 93.2% and 96.0%, respectively. The effects of different loading amounts on the removal rate of electrolytic catalytic trichloroacetic acid degradation are shown in Figure 4 .
[0052] Example 5:
[0053] On the basis of Example 1, the pH in the electrolytic cell was changed to 11, 9, 7, 5 and 3, the initial concentration of trichloroacetic acid was 200 μg / L, the current density was 50 mA / cm 2 , the loading amount is 4 mg / cm 2 The effect of different solution pH on electrolysis is as follows: Figure 5 As shown in the figure, the experimental results show that acidic conditions are more conducive to the electrolysis of the modified electrode. Acidic conditions will promote the generation of active H* and improve the catalytic reduction of trichloroacetic acid. At pH = 3, the removal rate can reach 96.9%. In the alkaline range of pH 9 to 11, trichloroacetic acid can still achieve a removal effect of more than 79.0%.
[0054] The Fe@C nanomaterial of the present invention can achieve a close connection between the modified layer and the cathode material through magnetic adsorption on the electrode material, while facilitating recovery and regeneration. During the electrolysis process, electron transfer on the magnetic electrode and the good catalytic activity of the Fe@C nanomaterial form a reducing agent with dehalogenation ability, achieving C-X bond cleavage, thereby dehalogenating halogenated disinfection byproducts. The present invention uses trichloroacetic acid as a typical halogenated disinfection byproduct. The C-Cl bond is more difficult to break than the C-Br and C-I bonds. The dechlorination effect of trichloroacetic acid further illustrates the catalytic dehalogenation effect of the composite electrode. The composite electrode of the present invention is suitable for degrading halogenated disinfection byproducts in drinking water, reducing toxicity and further improving the safety of drinking water quality.
[0055] The present invention has a current density of 50mA / cm 2 , 200 μg / L trichloroacetic acid solution, solution volume 1L, solution pH 7, by MMEE addition method, the loading amount of Fe@C nanomaterials on the modified electrode is 4 mg / cm 2 Under the condition of 8 hours of electrolysis, the dechlorination effect of trichloroacetic acid reached more than 96.0%, and the dechlorination efficiency was increased by 15% compared with the bare electrode.
[0056] The above is only the best specific implementation method of the present invention, and the present invention is not limited to this. Any technician who understands the field to which the present invention relates, within the technical scope provided by the present invention, all changes or replacements that can be easily made should also fall within the scope of protection of the present invention.
Claims
1. A method for removing halogenated acetic acid in water using Fe@C nanomaterials, characterized in that: The following steps are involved: S1. Obtaining metal Fe organic framework material; S2, carbonizing the metal Fe organic framework material at high temperature to obtain Fe@C nanomaterial; S3, adding the Fe@C nanomaterial to the water to be treated in the electrolytic cell device to perform electrolytic dehalogenation of the halogenated acetic acid; In step S1, during the preparation of the metal Fe organic framework material, terephthalic acid and ferric chloride hexahydrate are used as precursors, which are added to a DMF solution and then prepared by a hydrothermal method to prepare the metal Fe organic framework material; the molar ratio of the terephthalic acid, ferric chloride hexahydrate and DMF solution is 1:1:280, and the mixture is stirred at a medium temperature of 20-25°C for 2 hours. During the hydrothermal preparation process, the reaction is carried out at 150°C for 2 hours; In step S2, during the high-temperature carbonization process, the temperature is increased at a rate of 5°C / min in a tube furnace under nitrogen conditions and the reaction is carried out at 800°C; In step S3, the electrolytic cell device uses Fe@C / magnetic electrode as cathode and graphite electrode as anode, and the current density is 10~50mA / cm 2 The Fe@C nanomaterial is added in a manner to modify the magnetic electrode to prepare Fe@C / modified magnetic electrode material; During the preparation of the Fe@C / modified magnetic electrode: 1) Preparation of Fe@C nanomaterial dispersion; 2) The magnetic electrode is polished with 600-1000 mesh sandpaper until there is no obvious dirt, and then an aluminum oxide polishing liquid is applied to the surface and polished with the sandpaper until it is a bright mirror surface, and then rinsed with pure water; then ultrasonically cleaned in anhydrous ethanol and pure water and dried; then the Fe@C nanomaterial dispersion is absorbed and drop-coated on the surface of the magnetic electrode and dried to obtain a Fe@C / modified magnetic electrode; the loading amount of the Fe@C material on the surface of the magnetic electrode is not more than 8 mg / cm 2 .
2. The method for removing halogenated acetic acid in water according to claim 1, wherein The magnetic electrodes are made of neodymium iron boron magnets.
3. The method for removing halogenated acetic acid in water according to claim 1, wherein In step 1), during the process of preparing the Fe@C nanomaterial dispersion, the Fe@C nanomaterial is added into pure water and ultrasonically dispersed to obtain the Fe@C nanomaterial dispersion.