A Cu x Use of CuO@mC material in electrochemical dechlorination of chlorinated disinfection by-products

Abstract

The application discloses a kind of Cu x O@mC material in chlorinated disinfection by-product electrochemical dechlorination application, including the following steps: S1, obtaining metal Cu organic framework material and carbonization preparation Cu x O@mC material;S2, Cu x O@mC material is added to the aqueous solution containing halogenated acetic acid, and electrolytic dehalogenation is carried out by electrolytic cell device.The electrolytic cell device uses Cu x O@mC / metal electrode as cathode, and graphite electrode as anode.The Cu x O@mC / metal electrode can be used for chlorinated disinfection by-product electrochemical dechlorination.The method for dechlorination of the target object disclosed in the application has the advantages of high targeting, high dechlorination efficiency, low cost, simple structure, safety and stability, and the dissolution rate of copper ions is extremely low during use, which does not cause secondary pollution, and realizes the safe control of chlorinated disinfection by-products in water.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of drinking water safety guarantee, and particularly relates to an electrolytic treatment method for dechlorination and toxicity reduction of chlorinated disinfection byproducts. x Preparation of Cu BACKGROUND

[0002] Disinfection is a key step for inactivating pathogenic microorganisms in drinking water treatment. Chlorine disinfection is the most widely used disinfectant in domestic drinking water treatment. However, chlorine disinfection will form harmful disinfection byproducts (DBPs) through a series of reactions such as substitution and addition with organic matter while inactivating microorganisms.

[0003] Halogenated acetic acids (HAAs) are the main category of DBPs detected in drinking water, accounting for a large proportion of the total amount of DBPs. HAAs can cause cancer, deformity and mutation, such as metabolic disorder, eye damage, reproductive and embryonic toxicity, nerve poisoning, infertility and increased liver peroxisome, which are harmful to human body and are the primary factor constituting the three hazards of disinfection byproducts. Compared with halogenated methane and halogenated acetonitrile and other DBPs, HAAs cannot be lost in the heating treatment of daily water due to low volatility, and have the highest residual rate. Under the background of the widespread use of chlorine disinfection, the generation of DBPs in drinking water is inevitable, so it is an important direction to develop a technology for easy decentralized application for reducing the amount of generated DBPs to solve the problem of DBP pollution in drinking water.

[0004] The toxicity of chlorinated disinfection byproducts mainly comes from chlorine in the molecular structure, and the breaking of C-Cl bond can achieve the reduction of DBP toxicity. The present application uses an electrochemical technology for dechlorination of DBPs, which has the advantages of mild reaction conditions, simple reactor, good reaction selectivity, low equipment and operation cost, less toxic byproducts, no secondary pollution, and high sensitivity. A safe material with high catalytic activity is provided, which can realize efficient catalysis of electrochemical dechlorination treatment, improve the dechlorination efficiency and rate of DBPs, reduce the energy demand of the reaction system, and promote the development of drinking water safety guarantee theory and technology. SUMMARY

[0005] In view of the above technical problems existing in the prior art, the present application provides a preparation method of Cu x O@mC material and its application in electrochemical dechlorination of chlorinated disinfection byproducts, aiming to reduce the content of chlorinated disinfection byproducts in drinking water. Based on the reduction reaction mechanism of chlorinated organic matter in cathode dechlorination degradation, the present application can develop a cathode material with catalytic function to modify the metal electrode with Cu x O@mC porous carbon as a catalyst, and Cu xO@mC material recycling; electron transfer on metal electrode in electrolysis process and Cu x O@mC Good catalytic activity forms a reducing agent with dehalogenation ability, realizes C-Cl bond rupture, makes chlorinated disinfection by-products dechlorination, reduces its toxicity, and improves drinking water quality.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A Cu x O@mC material in the electrochemical dechlorination of chlorinated disinfection by-products, comprising the following steps:

[0008] S1, obtaining a metal Cu organic framework material and carbonizing to prepare Cu x O@mC material; wherein x represents a multiple valence state, which can be 0, +1, +2 valence;

[0009] S2, adding Cu x O@mC material to an aqueous solution containing halogenated acetic acid and carrying out electrolytic dehalogenation by an electrolytic cell device.

[0010] Further, in step S1, the metal Cu organic framework material is prepared by the following method:

[0011] Dissolve Cu(NO3)2·3H2O in water, dissolve 1,3,5-benzene tricarboxylic acid in anhydrous ethanol, mix the two, stir to form a blue mud-like mixture; wherein the volume ratio of water to anhydrous ethanol is 1:1, the molar ratio of Cu(NO3)2·3H2O to 1,3,5-benzene tricarboxylic acid is 9:5; the concentration of Cu(NO3)2·3H2O is 0.3 mol / L;

[0012] The blue mud-like mixture is kept at 120℃ for constant temperature reaction, then washed and dried to obtain the metal Cu organic framework material.

[0013] Further, in step S1, the carbonization of Cu x O@mC material is prepared by the following method:

[0014] The metal Cu organic framework material is heated at a rate of 5℃ / min under nitrogen conditions, and kept at a temperature of 300℃ for constant temperature reaction to obtain Cu x O@mC material.

[0015] Further, in step S2, the electrolytic cell device uses graphite electrode as anode, Cu x O@mC / metal electrode as cathode, and the current density is 10-50mA / cm 2 , preferably the current density is 50mA / cm 2 . The Cux The Cu x O@mC material is added to modify the metal electrode to prepare a Cu

[0016] Further, the metal electrode is one of steel, copper and iron, and preferably the metal electrode is a steel electrode.

[0017] Further, the Cu x O@mC / metal composite electrode is prepared by the following method:

[0018] 1) preparing a Cu x O@mC dispersion liquid;

[0019] 2) cleaning the metal electrode;

[0020] 3) adding the Cu x O@mC dispersion liquid to the cleaned metal electrode, and drying to obtain a Cu x O@mC / metal composite electrode, wherein the Cu x O@mC / metal composite electrode has a Cu x O@mC material loading of no more than 6 mg / cm 2 , and preferably the loading is 6 mg / cm 2 .

[0021] Further, in step 1), the Cu x O@mC dispersion liquid is prepared by the following method:

[0022] The Cu x O@mC material is dispersed in a solvent containing a carrier material, and ultrasonic treatment is performed to obtain a Cu x O@mC dispersion liquid; the Cu x O@mC material is added in an amount of 50 mg / mL by volume of anhydrous ethanol, the carrier material is a polymer perfluorosulfonic acid, i.e. Nafion, and the amount added is 5 μL / mL by volume of anhydrous ethanol, and the ultrasonic treatment is performed at 50 Hz.

[0023] Further, in step 2), the metal electrode is cleaned by the following method:

[0024] The metal electrode is polished to a bright mirror surface using an alumina dispersion liquid, and then washed with pure water, and then sequentially placed in anhydrous ethanol and pure water, and each is ultrasonically treated at 50 Hz, and finally dried for standby use.

[0025] A Cu x O@mC material, the Cu x O@mC material has hydrophobicity, is easy to separate from water, and is convenient for recycling.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] Firstly, the application utilizes Cu x O@mC material, and effectively removes chlorinated disinfection byproducts in water through an electrochemical reduction method, has simple operation, convenient management, and wide social and economic benefits.

[0028] Secondly, the application creatively utilizes Cu x O@mC material, which not only has a large specific surface area and rich pore structure, but also has multi-valence copper element synergistic catalysis, so that the catalytic activity can be greatly improved, and efficient dechlorination of chlorinated disinfection byproducts can be realized.

[0029] Thirdly, Cu x O@mC has good hydrophobicity, is easy to separate from water, and is convenient for recycling.

[0030] Fourthly, the application loads Cu x O@mC on a metal electrode, so that the electrode can be efficiently recycled.

[0031] Fifthly, the preparation of the modified electrode is simple, the concentration of dissolved metal ions is extremely low, and there is no secondary pollution. DETAILED DESCRIPTION OF DRAWINGS

[0032] Figure 1 The XRD pattern of Cu x O@mC material of the application

[0033] Figure 2 The SEM pattern of Cu x O@mC material under different magnifications ((a) 10 μm, (b) 1 μm)

[0034] Figure 3 The comparison chart of the influence of different electrode materials on the removal rate of trichloroacetic acid

[0035] Figure 4 The comparison chart of the influence of different current densities on the removal rate of trichloroacetic acid

[0036] Figure 5 The comparison chart of the influence of different Cu x O@mC loadings on the removal rate of trichloroacetic acid

[0037] Figure 6 The comparison chart of the influence of different pH values on the removal rate of trichloroacetic acid

[0038] Figure 7 The comparison chart of the influence of different substrate concentrations on the removal rate of trichloroacetic acid

[0039] Figure 8 A schematic diagram of the electrocatalytic trichloroacetic acid dechlorination device of the present application. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be further described below with specific implementation cases and in combination with the drawings. The actual cases only serve to illustrate and describe the present application, and are not limiting conditions of the present application. The instruments and reagents used in the cases are not marked with the manufacturer, and are all conventional products that can be purchased through normal procurement channels.

[0041] Example 1:

[0042] In the actual case, the electrocatalytic degradation of trichloroacetic acid dechlorination is carried out at room temperature of 25℃.

[0043] This embodiment provides a Cu x O@mC material and its application in electrochemical dechlorination of chlorinated disinfection by-products, which specifically includes the following steps:

[0044] S1, obtaining a metal Cu organic framework material and carbonizing to prepare a Cu x O@mC material.

[0045] Dissolve Cu(NO3)2·3H2O in water, dissolve 1,3,5-benzene tricarboxylic acid in anhydrous ethanol, mix the two, stir to form a blue mud-like mixture; wherein the volume ratio of water to anhydrous ethanol is 1:1, the molar ratio of Cu(NO3)2·3H2O to 1,3,5-benzene tricarboxylic acid is 9:5; the concentration of Cu(NO3)2·3H2O is 0.3mol / L; the volume of anhydrous ethanol is 12ml. The blue mud-like mixture is reacted at 120℃ for 24h, and then filtered and washed with a mixed solvent of pure water and anhydrous ethanol, wherein the volume ratio of anhydrous ethanol to pure water is 1:1; finally, dry at 120℃ for 16h to obtain a metal Cu organic framework material.

[0046] The metal Cu organic framework material is heated at a rate of 5℃ / min under nitrogen conditions, and reacted at a temperature of 300℃ for 1h to obtain a Cu x O@mC material.

[0047] S2, adding the Cu x O@mC material to an aqueous solution containing halogenated acetic acid to carry out electrolytic dehalogenation by an electrolytic cell device.

[0048] The electrolytic cell device uses Cu x O@mC / steel composite electrode as the cathode, and graphite electrode as the anode, and the Cu x O@mC material is added by modifying the steel electrode to prepare a Cu xO@mC / steel composite electrode; a 2L beaker was used as the electrolytic cell, a clamping groove was set at the bottom of the cell for fixing the electrode sheets, the distance between the electrode sheets was 30mm; the electrolytic cell was wrapped with tin foil paper to create a light-proof environment, a rotor was set in the electrolytic cell, and the rotor was uniformly reacted by magnetic stirring at a speed of 150rpm. The electrolytic cell device is shown in Figure 8 .

[0049] The Cu x O@mC / steel composite electrode was prepared by the following method:

[0050] 1) preparing a Cu x O@mC dispersion solution;

[0051] 2) cleaning the steel electrode;

[0052] 3) a certain amount of the Cu x O@mC dispersion solution was drop-coated on the cleaned steel electrode by using a syringe, and the Cu x O@mC / steel composite electrode was obtained after air-drying, wherein the Cu x O@mC material on the Cu x O@mC / steel composite electrode had a loading amount of 2mg / cm 2 .

[0053] In step 1), the Cu x O@mC dispersion solution was prepared by the following method:

[0054] 500mg Cu x O@mC was dispersed in 10.0mL anhydrous ethanol containing 50μL Nafion, and ultrasonic treatment was performed under the condition of a frequency of 50Hz for 30min, to obtain a standard Cu x O@mC dispersion solution with a concentration of 50mg / ml.

[0055] In step 2), the steel electrode was cleaned by the following method:

[0056] A steel electrode with a size of 40×70×2mm was polished by using 800-mesh sandpaper, and then polished to a bright mirror surface by using a 20wt.% alumina dispersion solution, and then washed with pure water, and then sequentially placed in anhydrous ethanol and pure water, and each was ultrasonically treated under the condition of 50Hz for 20min, and finally air-dried for standby use.

[0057] S3, prepare 1L of trichloroacetic acid solutions with initial concentrations of 50, 100, 200, 300 and 450μg / L, and sequentially perform electrolysis reactions. Adjust the pH of the solution to 7, and the current density is 30mA / cm 2The samples were taken at 0, 1, 2, 4, 6 and 8 h, respectively, and two groups were taken as parallel samples each time. The treated samples were determined by GC-ECD.

[0058] Cu x O@mC modified electrode electrocatalytic dechlorination, when the initial concentration of trichloroacetic acid was 450 μg / L, after electrolysis for 8 h, the removal rate of trichloroacetic acid was 58.0%, when the substrate concentration was 300, 200 and 100 μg / L, after electrolysis for 8 h, the removal rates of trichloroacetic acid were 67.3%, 77.7% and 81.8%, respectively. When the substrate concentration was 50 μg / L, after electrolysis for 8 h, the removal rate of trichloroacetic acid reached 85.1%. The electrolytic dechlorination process conforms to the first-order reaction kinetics, and the dechlorination effect of trichloroacetic acid with different initial concentrations over time is shown in Figure 7 .

[0059] Example 2:

[0060] The crystal structure of Cu x O@mC material in Example 1 was characterized by XRD, and the results are shown in Figure 1 . The diffraction peaks at 2θ = 43.3° and 50.5° are attributed to the (111) and (200) crystal planes of Cu, respectively; the diffraction peak at 2θ = 74.2° is attributed to the (220) crystal plane of CuO; and the diffraction peak at 2θ = 36.5° is attributed to the (111) crystal plane of Cu2O. Cu is easily oxidized to high valence state in oxidizing environment, or reduced to elemental state under reducing conditions, and the coexistence of multiple valence states is beneficial to improve the catalytic activity of the material.

[0061] Example 3:

[0062] On the basis of Example 1, the dechlorination reaction of trichloroacetic acid by electrocatalytic degradation with different electrodes was studied to determine the optimal electrode. The research objects were copper (Cu) electrode, iron (Fe) electrode, steel (St) electrode, Cu x O@mC / Cu composite electrode, Cu x O@mC / Fe composite electrode, Cu x O@mC / St composite electrode. The initial concentration of trichloroacetic acid was 200 μg / L, the current density was 50 mA / cm 2 , the pH of aqueous solution was 7, and the Cu x O@mC loading of each composite electrode was 2 mg / cm 2 . Under the condition of electrolysis for 8 hours, the removal rates of trichloroacetic acid by Cu, Fe and St electrodes as cathode were 55.9%, 69.1% and 75.8%, respectively. The dechlorination effect was obviously improved by using modified electrode to electrolyze trichloroacetic acid, and the removal rates of trichloroacetic acid by Cu x O@mC / Cu, Cu xO@mC / Fe, Cu x The degradation rates of O@mC / St were 80.8%, 82.6%, and 85.2%, respectively. Compared with the corresponding bare electrodes, the removal rates were increased by 24.9%, 13.5%, and 9.4%, respectively. The effects of different electrode materials on the removal rates of trichloroacetic acid are shown in Figure 3 .

[0063] Example 4:

[0064] On the basis of Example 1, the effects of different current densities on the removal rates of trichloroacetic acid were investigated. The initial concentration of trichloroacetic acid was 200 μg / L, the pH of the aqueous solution was 7, the Cu x O@mC / steel composite electrode had a loading of 2 mg / cm 2 , 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 65.9%, 73.9%, 77.7%, 80.5%, and 85.2%, respectively. The removal effect increased with the increase of the current density. The experimental results are shown in Figure 4 .

[0065] Example 5:

[0066] On the basis of Example 1, the loading of Cu x O@mC on the Cu x O@mC / steel composite electrode was changed to 0, 1, 2, 4, and 6 mg / cm 2 , respectively. The initial concentration of trichloroacetic acid was 200 μg / L, the current density was 30 mA / cm 2 , and the pH of the aqueous solution was 7. The effects of different loadings on the removal rates of electrolytic catalytic trichloroacetic acid degradation are shown in Figure 5 . As the loading increased, the removal rate of trichloroacetic acid gradually increased within 8 hours. When the loading was 6 mg / cm 2 , the removal rate could reach 88.6%.

[0067] Example 6:

[0068] On the basis of Example 1, the pH in the electrolytic cell was changed to 11, 9, 7, 5, and 3, respectively. The initial concentration of trichloroacetic acid was 200 μg / L, the current density was 30 mA / cm 2 , and the loading was 2 mg / cm 2 . The effects of different solution pH on electrolysis are shown in Figure 6 . According to the experimental results, the electrolysis of the modified electrode is more favorable under acidic conditions. The production of active H* is promoted under acidic conditions, which improves the catalytic reduction of trichloroacetic acid. When the pH is 3, the removal rate can reach 85.0%. There is still a certain removal effect on trichloroacetic acid under alkaline conditions.

[0069] In summary, this application provides a Cu x O@mC material, using trichloroacetic acid as a typical chlorinated disinfection byproduct for electrocatalytic dechlorination, the method used in this application significantly improved the degradation rate of trichloroacetic acid. x The O@mC-modified steel electrode can achieve electrocatalytic dechlorination of trichloroacetic acid in water. Under the condition of 8 hours of electrolysis, the dechlorination rate is as high as over 85%. In addition, the preparation of the modified electrode is simple, the metal ion dissolution concentration is extremely low, there is no secondary pollution, and the electrode recycling rate is high, providing data support and theoretical support for drinking water safety.

[0070] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A Cu x The application of O@mC material in electrochemical dechlorination of chlorinated disinfection byproducts is characterized by: The following steps are involved: S1. Obtaining metal Cu organic framework material and carbonizing it to prepare Cu x O@mC materials; S2, Cu x The O@mC material is added to an aqueous solution containing halogenated acetic acid and then electrolytically dehalogenated by an electrolytic cell device. In step S1, the metal Cu organic framework material is prepared by the following method: Dissolve Cu(NO3)2·3H2O in water and dissolve 1,3,5-benzenetricarboxylic acid in anhydrous ethanol, mix the two, and stir to form a blue slurry-like mixture; wherein the volume ratio of water to anhydrous ethanol is 1:1, the molar ratio of Cu(NO3)2·3H2O to 1,3,5-benzenetricarboxylic acid is 9:5; and the concentration of Cu(NO3)2·3H2O is 0.3 mol / L; The blue slurry-like mixed solution is subjected to a constant temperature reaction at 120° C., and then washed and dried to obtain a metal Cu organic framework material; In step S1, the carbonization preparation of Cu x The O@mC material was prepared by the following method: The Cu organic framework material was heated at a rate of 5°C / min under nitrogen conditions and reacted at a constant temperature of 300°C to obtain Cu x O@mC materials; In step S2, the electrolytic cell device uses a graphite electrode as an anode, Cu x The O@mC / metal electrode is the cathode, and the current density is 10~50mA / cm 2 , the Cu x The addition method of O@mC material is to modify the metal electrode to prepare Cu x O@mC / metal composite electrode; The Cu x O@mC material is hydrophobic.

2. The use of the electrochemical dechlorination of chlorinated disinfection by-products according to claim 1, characterized in that: The metal electrode is one of steel, copper and iron.

3. The use of the electrochemical dechlorination of chlorinated disinfection by-products according to claim 1, characterized in that: The Cu x The O@mC / metal composite electrode was prepared by the following method: 1) Preparation of Cu x O@mC dispersion; 2) Clean the metal electrodes; 3) The Cu x The O@mC dispersion droplets were applied to the cleaned metal electrode and dried to obtain Cu x O@mC / metal composite electrode, the Cu x Cu on O@mC / metal composite electrode x The loading of O@mC material is no more than 6 mg / cm 2 .

4. The use of the electrochemical dechlorination of chlorinated disinfection by-products according to claim 3, characterized in that: In step 1), the Cu x The O@mC dispersion was prepared by the following method: Cu x O@mC material was dispersed in a solvent containing a carrier material and Cu was prepared by ultrasonication. x O@mC dispersion; Cu x The addition amount of O@mC material is 50 mg / mL based on the volume of anhydrous ethanol. The carrier material is polymer perfluorosulfonic acid, namely Nafion, and the addition amount is 5 μL / mL based on the volume of anhydrous ethanol. The ultrasound is performed at 50 Hz.

5. The use of the electrochemical dechlorination of chlorinated disinfection by-products according to claim 3, characterized in that: In step 2), the metal electrode is cleaned by the following method: Take a metal electrode and grind it with sandpaper, then polish it to a bright mirror surface with alumina dispersion, rinse it with pure water, and then place it in anhydrous ethanol and pure water in turn, ultrasonically treat each at 50 Hz, and finally dry it for use.

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