A method for electrocatalytic hydrogenative dehalogenation of haloacetic acids or halomethanes in an aqueous body

Abstract

This invention discloses a method for the electrocatalytic hydrogenation dehalogenation of haloacetic acids or halomethanes in water. A conductive material surface-modified with ruthenium or platinum is used as the catalytic cathode, and water is used as the hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acids or halomethanes in water into acetic acid or methane. The precious metals in the catalytic cathode of this invention are cheaper; the unit price of ruthenium is much lower than that of palladium and rhodium. Compared with palladium-modified catalytic cathodes, the dechlorination selectivity is higher, with an 11.7% increase in the selectivity for the hydrogenation and dechlorination of trichloroacetic acid in water to acetic acid.

Description

(I) Technical Field

[0001] This invention belongs to the field of electrochemical water treatment, specifically relating to a method for electrochemically hydrogenating and dehalogenating haloacetic acid or halomethane in water into acetic acid and methane using a conductive material with surface-modified ruthenium or platinum as the catalytic cathode and water as the hydrogen source. (II) Background Technology

[0002] Haloacetic acids and halomethanes are common halogenated organic pollutants in drinking water, surface water, and groundwater. These pollutants are characterized by low concentration, high toxicity, and difficulty in treatment. If left uncontrolled or untreated, they can cause great harm to the ecological environment and human health. Electrochemical methods using surface-modified palladium conductive materials as catalytic cathodes can remove haloacetic acids and trihalomethanes from water at room temperature and pressure, but this method suffers from incomplete dehalogenation. Taking the electrochemical catalytic hydrogenation dechlorination of trichloroacetic acid in water as an example, current electrochemical catalytic hydrogenation methods using surface-modified palladium conductive materials usually produce a high proportion of monochloroacetic acid as the final product [Electrochimica Acta 232 (2017) 13–21], while the toxicity of monochloroacetic acid is nearly 50 times that of trichloroacetic acid [Fundam. Appl. Toxicol. 17, 240–253 (1991)].

[0003] Existing methods disclose an electrochemical catalytic hydrogenation method using rhodium-containing materials as catalysts. The hydrogen in this method is generated in situ by electrolysis of water and can selectively hydrogenate and dehalogenate various haloacetic acids into acetic acid [Nature Water, 2023, 1(1): 95-103]. However, the rhodium in the catalyst used in this method is too expensive and requires a large amount of palladium metal (palladium film), making it difficult to apply on a large scale. (III) Summary of the Invention

[0004] The purpose of this invention is to provide a method for the electrocatalytic hydrogenation dehalogenation of haloacetic acids or halomethanes in water. The method uses a conductive material with surface modification of ruthenium or platinum as the catalytic electrode and water as the hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acids or halomethanes in water into acetic acid or methane. The method of this invention, by using a conductive material with surface modification of ruthenium or platinum, can not only reduce the unit price and amount of precious metals used, but also has the advantage of high dehalogenation selectivity.

[0005] The technical solution adopted in this invention is:

[0006] This invention provides a method for electrocatalytic hydrogenation dehalogenation of haloacetic acid or halomethane in water. The method uses a conductive material with surface-modified ruthenium or platinum as a catalytic electrode and water as a hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acid or halomethane in water into acetic acid or methane.

[0007] Furthermore, the haloacetic acid includes trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, dibromoacetic acid, and monobromoacetic acid; the halomethane includes trichloromethane, dichloromethane, monochloromethane, monobromodichloromethane, tribromomethane, and dibromochloromethane.

[0008] Furthermore, the conductive material is any conductive solid material that is chemically stable under the reaction conditions, including metallic or carbon materials.

[0009] Furthermore, the metallic materials include nickel, titanium, copper, silver, stainless steel, etc.; the carbon materials include carbon paper, activated carbon, carbon fiber, graphite felt, foamed glass carbon, etc.

[0010] Furthermore, the electrode is Ru / Ni, Ru / stainless steel, Ru / graphite felt, Ru / C / carbon paper, Ru / Al2O3 / carbon paper, Pt / Ni, Pt / stainless steel, or Pt / graphite felt.

[0011] Furthermore, the temperature range of the electrochemical hydrogenation dehalogenation reaction is 5–90°C, and the potential is -0.5V to -0.8V vs. silver / silver chloride reference electrode.

[0012] Furthermore, the concentration of haloacetic acid or halomethane in the water body ranges from 10 μg / L to 1 g / L, preferably 3 mg / L.

[0013] Furthermore, the water body includes drinking water, surface water, or groundwater.

[0014] The electrocatalytic hydrogenation dehalogenation of haloacetic acid or halomethane in water, as described in this invention, is carried out in a diaphragm electrolyzer according to the following steps: A diaphragm electrolyzer is used as the reactor, a cation exchange membrane as the diaphragm, a conductive material with ruthenium or platinum surface modification as the cathode, iridium oxide-modified titanium as the anode, a sodium sulfate aqueous solution as the anolyte, and water containing haloacetic acid or halomethane + sodium sulfate (pH = 7.2) as the catholyte. The catholyte temperature is controlled at 5-90℃ (preferably 25℃), and the cathode potential is -0.5V vs. a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution). After reacting for 60 minutes, the haloacetic acid or halomethane in the water is electrochemically hydrogenated and dehalogenated into acetic acid or methane. The concentration of the sodium sulfate aqueous solution in the anolyte is 5 mM; the concentration of sodium sulfate in the catholyte is 1-5 mM (preferably 2 mM), and the concentration of haloacetic acid or halomethane is 10 μg / L-1 g / L, preferably 1-5 mg / L (more preferably 3 mg / L).

[0015] The electrocatalytic hydrogenation dehalogenation of haloacetic acid or halomethane in water according to the present invention is carried out in a diaphragm-free electrolytic cell according to the following steps: a diaphragm-free beaker is used as the reactor, a conductive material with ruthenium or platinum surface modification is used as the cathode, titanium modified with iridium oxide is used as the electrode, and water containing haloacetic acid or halomethane + sodium sulfate (pH=7.2) is used as the electrolyte. The electrolyte temperature is controlled at 5-90℃ (preferably 25℃), and the electrode potential is -0.8V vs. silver / silver chloride reference electrode (saturated potassium chloride aqueous solution). After reacting for 60 min, the haloacetic acid or halomethane in the water is electrochemically hydrogenated and dehalogenated into acetic acid or methane. The sodium sulfate concentration in the electrolyte is 1-5 mM (preferably 2 mM), and the concentration of haloacetic acid or halomethane is 10 μg / L-1 g / L, preferably 1-5 mg / L (more preferably 3 mg / L).

[0016] The ruthenium or platinum content, current density, or electrode potential on the surface of the conductive material are not key factors in this invention and can vary depending on the concentrations of haloacetic acid and halomethane. Preferably, the ruthenium or platinum content is 0.1-3 mg / cm² based on the surface area of ​​the conductive material. 2 More preferably 1 mg / cm 2 .

[0017] The method of modifying conductive materials with ruthenium or platinum is not a key factor of this invention; modification can be performed by electroplating or electroless plating; or by brush coating with Nafion as a binder. When modifying by brush coating, ruthenium or platinum can be first loaded onto a carbon support or onto a metal oxide, such as aluminum oxide, titanium oxide, and cerium oxide.

[0018] The type of electrochemical reactor and the anode material are not key factors in this invention; the reaction can be carried out in a diaphragm electrochemical reactor or a diaphragm-free electrochemical reactor. The anode material can be any material stable in the reaction system, such as a titanium anode or a noble metal-modified titanium anode (iridium oxide-modified titanium anode).

[0019] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: (1) The present invention uses a conductive material with surface-modified ruthenium or platinum as the catalytic electrode. The unit price of ruthenium or platinum is much lower than that of rhodium, and palladium is not required, which effectively reduces the cost of the reaction device; (2) Compared with palladium-modified catalytic cathode, the conductive material with surface-modified ruthenium or platinum as the catalytic cathode of the present invention has higher dechlorination selectivity, and the selectivity of hydrogenation dechlorination of trichloroacetic acid to acetic acid in water is increased by 11.7%. (iv) Description of the attached drawings

[0020] Figure 1 Ion chromatograms of the reaction solution before and after the reaction.

[0021] Figure 2 Schematic diagram of an electrolytic cell. (V) Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0023] In the following examples, the electrochemical reactor and components were provided by Hangzhou Sai'ao Electrochemical Instrument Co., Ltd. Unless otherwise specified, the cathode or anode was purchased from Hangzhou Sai'ao Electrochemical Instrument Co., Ltd. The initial pH of the catholyte or electrolyte was adjusted using sulfuric acid or sodium hydroxide.

[0024] Conversion rate yield Selective Where C0 is the initial molar concentration of reactants, C1 is the molar concentration of reactants at the end of the reaction, and C2 is the molar concentration of the target product at the end of the reaction.

[0025] Example 1: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water

[0026] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru-modified nickel foam as the cathode (Ru / Ni, 2×4cm),... 2 Ru content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V vs. a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution). The reaction was carried out for 60 min, and samples were taken before and after the reaction for ion chromatography detection. The results are shown in the figure. Figure 1 The conversion rate of trichloroacetic acid in tap water was 100%, the yield of acetic acid was 97.4%, and the selectivity of acetic acid was 97.4%.

[0027] The preparation method of Ru-modified nickel foam is as follows: First, nickel foam (25mm×25mm×1.2mm) is ultrasonically treated in acetone for 20min, and then... -1 The nickel foam was soaked in HNO3 aqueous solution for 5 min, and then washed with a large amount of deionized water. Then, using the nickel foam as the cathode and a platinum sheet electrode as the anode, a solution containing 0.3 mmol·L⁻¹ was applied. -1 RuCl3 and 0.1 mol·L -1 The aqueous solution of aminosulfonic acid is used as the cathode electrolyte, containing 0.5 mol·L⁻¹. -1 An aqueous solution of Na₂SO₄ was used as the anolyte, and an application of 0.1 A·cm⁻¹ was applied. -2Electrodeposition was performed using a current density to obtain ruthenium-supported nickel foam (Ru / Ni).

[0028] Ion chromatography analysis conditions: A Dionex ICS-2100 ion chromatograph was used, with a Dionex Ion Pac AG19 anion guard column (50 mm × 4 mm) and an Ion Pac AS19 anion separation column (250 mm × 4 mm); an ASRS-ULTRA anion suppressor (4 mm); eluent: KOH isocratic elution, gradient program 0–40 min, 8 mmol / L; flow rate: 1 mL / min; injection volume: 25 μL; column temperature: 30℃; detection cell temperature: 35℃; suppressor current: 20 mA; conductivity detection; external standard method for quantification.

[0029] Examples 2-6: Electrochemical hydrogenation dehalogenation reactions of different halogenated organic compounds in tap water

[0030] The trichloroacetic acid in Example 1 was replaced with the same amount of the reactants shown in Table 1, and other operations were the same. The results are shown in Table 1. It can be seen that various haloacetic acids and halomethanes can be electrochemically hydrogenated and dehalogenated to acetic acid or methane with high selectivity under the experimental conditions of Example 1.

[0031] Table 1 Electrochemical hydrogenation dehalogenation reactions of different halogenated organic compounds in tap water

[0032]

[0033] Unless otherwise specified, the reaction conditions are the same as in Example 1.

[0034] Examples 7-13: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water—different catalytic cathodes

[0035] The catalytic cathode in Example 1 was replaced with the catalytic cathode shown in Table 2, and other operations were the same. The results are shown in Table 2. It can be seen that various catalytic cathodes modified with ruthenium or platinum can electrochemically hydrogenate and dechlorinate trichloroacetic acid to acetic acid with high selectivity.

[0036] Table 2 Electrochemical hydrogenation dechlorination reactions of trichloroacetic acid at different catalytic cathodes

[0037]

[0038]

[0039] Unless otherwise specified, the reaction conditions were the same as in Example 1, and the concentration of noble metals at the catalytic cathode was 1 mg / cm³. 2 .

[0040] aPreparation method of Ru / SS and Ru / GF: Replace nickel foam (25mm×25mm×1.2mm) with 3 layers of 304 stainless steel mesh (25mm×25mm×0.2mm) or graphite felt (25mm×25mm×2mm), and the remaining reaction conditions are the same as the preparation method of Ru-modified nickel foam in Example 1.

[0041] b The preparation methods of Ru / C / CP and Ru / Al2O3 / CP are as follows: First, with a Ru content of 1 mg / cm³, 2 The standard weighing of Ru / C (Sigma-Aldrich, product number 206180) or Ru / Al2O3 (Sigma-Aldrich, product number 439916) is used. Then, isopropanol and ethanol are added in a 1:3 ratio to disperse the catalyst evenly. Next, Nafion solution is added at 5 times the weight of the catalyst and ultrasonically dispersed for 20 minutes to obtain a slurry. Finally, the slurry is evenly coated onto carbon paper with a brush at a temperature of 80℃~90℃. Ru / C / CP and Ru / Al2O3 / CP are obtained after the slurry solidifies.

[0042] c Preparation methods of Pt / Ni, Pt / SS and Pt / GF: "H2PtCl6 and HCl" are used instead of "RuCl3 and aminosulfonic acid". The conductive matrix materials are nickel foam (25mm×25mm×1.2mm), 3 layers of 304 stainless steel mesh (25mm×25mm×0.2mm) and graphite felt (25mm×25mm×2mm). The remaining reaction conditions are the same as those for the preparation of Ru-modified nickel foam in Example 1.

[0043] Examples 14-19: Electrochemical hydrogenation dechlorination of trichloroacetic acid in water—different temperatures, reactant concentrations, water bodies, and noble metal loadings.

[0044] According to the conditions in Table 3, Example 1 was adjusted, and other operations were the same. The results are shown in Table 3. It can be seen that in the temperature range of 5 to 40°C and the reactant concentration range of 10 μg / L to 1 g / L, trichloroacetic acid in tap water and well water can be hydrogenated and dechlorinated to acetic acid with high selectivity on Ru-modified nickel foam cathode.

[0045] Table 3 Hydrogenation and dechlorination reactions of trichloroacetic acid in water under different conditions.

[0046]

[0047] Unless otherwise specified, the reaction conditions are the same as in Example 1. a The Ru content in the catalytic cathode is 3 mg / cm³. 2 The reaction time is 6 hours; bThe Ru content in the catalytic cathode is 0.5 mg / cm³. 2 The reaction time is 40 minutes; c The Ru content in the catalytic cathode is 0.1 mg / cm³. 2 The reaction time is 20 minutes.

[0048] Example 20: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water

[0049] A diaphragmless beaker was used as the reactor, and Ru-modified nickel foam was used as the cathode (2×4cm). 2 Ru content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 Using 50 mL of tap water containing 3 mg / L trichloroacetic acid and 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) as the electrolyte, and controlling the cathode potential at -0.8 V with a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution), after 60 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 99.7%, the yield of acetic acid was 97.3%, and the selectivity of acetic acid was 97.6%.

[0050] Example 21: Electrochemical hydrogenation dechlorination reaction of trichloroacetic acid in tap water

[0051] For example Figure 2 The electrolytic cell shown is the reactor, the Nafion 324 membrane is the diaphragm, and the Ru / C particle layer bonded with Nafion resin is the cathode (2×4cm). 2 Ru content 1 mg / cm 2 The iridium oxide particle layer bonded with Nafion resin serves as the anode (2×4cm). 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of tap water containing 3 mg / L trichloroacetic acid (pH = 7.2, temperature = 25℃) was used as the catholyte, and 50 mL of deionized water was used as the anolyte. The cathode potential was controlled at -0.8 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 99.5%, the yield of acetic acid was 96.3%, and the selectivity of acetic acid was 96.8%.

[0052] Comparative Example 1: Electrochemical hydrogenation-dechlorination reaction of trichloroacetic acid in tap water

[0053] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Pd-modified nickel foam as the cathode (3×4cm) 2 Pd content 1 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4cm)2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 99.8%, the yield of monochloroacetic acid was 16.8%, the yield of acetic acid was 82.5%, and the selectivity of acetic acid was 85.7%. After 120 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of monochloroacetic acid was 16.1%, the yield of acetic acid was 83.7%, and the selectivity of acetic acid was 83.7%.

[0054] Compared to Example 1, the selectivity of acetic acid decreased by 11.7% for the same reaction time. Extending the reaction time did not change the selectivity of acetic acid significantly.

[0055] The preparation method of Pd-modified nickel foam is as follows: First, nickel foam (25mm×25mm×1.2mm) is ultrasonically treated in acetone for 20min, and then... -1 The nickel foam was soaked in HNO3 aqueous solution for 5 min, and then washed with a large amount of deionized water. Then, using the nickel foam as the cathode and a platinum sheet electrode as the anode, a solution containing 0.3 mmol·L⁻¹ was applied. -1 PdCl2 and 0.1 mol·L -1 An aqueous solution of HCl is used as the cathode electrolyte, containing 0.5 mol·L⁻¹. -1 An aqueous solution of Na₂SO₄ was used as the anolyte, and an application of 0.1 A·cm⁻¹ was applied. -2 Electrodeposition was performed at a current density to obtain nickel foam loaded with palladium (Pd / Ni).

[0056] Comparative Example 2: Electrochemical hydrogenation and dechlorination reaction of chloroform in tap water

[0057] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Pd-modified nickel foam as the cathode (3×4cm) 2 Pd content 1 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 250 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L chloroform + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of chloroform in the tap water was 99.7%, the total yield of dichloromethane and monochloromethane was 13.1%, the yield of methane was 86.6%, and the selectivity of methane was 86.9%. After 120 min of reaction, the conversion rate of chloroform in the tap water was 100%, the total yield of dichloromethane and monochloromethane was 11.1%, the yield of methane was 87.2%, and the selectivity of methane was 87.2%.

[0058] Compared to Example 5, the selectivity of methane decreased by 11.1% for the same reaction time. Extending the reaction time did not change the selectivity of methane significantly.

[0059] Comparative Example 3: Electrochemical hydrogenation-dechlorination reaction of trichloroacetic acid in tap water

[0060] An H-type electrolytic cell was used as the reactor, a Nafion 324 membrane as the diaphragm, and iridium-modified nickel foam as the cathode (3×4cm). 2 Iridium content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 99.8%, the yield of monochloroacetic acid was 11.3%, the yield of acetic acid was 88.1%, and the selectivity of acetic acid was 88.3%. After 120 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of monochloroacetic acid was 10.5%, the yield of acetic acid was 89.2%, and the selectivity of acetic acid was 89.2%.

[0061] Compared to Example 1, the selectivity of acetic acid decreased by 9.1% for the same reaction time. Extending the reaction time did not change the selectivity of acetic acid significantly.

[0062] The preparation method of iridium-modified nickel foam is as follows: First, nickel foam (25mm×25mm×1.2mm) is ultrasonically treated in acetone for 20min, and then... -1 The nickel foam was soaked in HNO3 aqueous solution for 5 min, and then washed with a large amount of deionized water. Then, using the nickel foam as the cathode and a platinum sheet electrode as the anode, a solution containing 0.3 mmol·L⁻¹ was applied.-1 IrCl3 and 0.1 mol·L -1 An aqueous solution of HCl is used as the cathode electrolyte, containing 0.5 mol·L⁻¹. -1 An aqueous solution of Na₂SO₄ was used as the anolyte, and an application of 0.1 A·cm⁻¹ was applied. -2 Electrodeposition was performed at a current density to obtain nickel foam loaded with palladium (Ir / Ni).

[0063] Comparative Example 4: Electrochemical hydrogenation-dechlorination reaction of trichloroacetic acid in tap water

[0064] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and silver-modified nickel foam as the cathode (3×4cm) 2 Silver content 1 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L trichloroacetic acid + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 95.2%, the yield of dichloroacetic acid was 9.8%, the yield of monochloroacetic acid was 11.5%, the yield of acetic acid was 74.3%, and the selectivity of acetic acid was 78.0%. After 120 min of reaction, the conversion rate of trichloroacetic acid in the tap water was 100%, the yield of monochloroacetic acid was 15.5%, the yield of acetic acid was 85.2%, and the selectivity of acetic acid was 85.2%.

[0065] Compared to Example 1, the selectivity of acetic acid decreased by 19.4% for the same reaction time.

[0066] The preparation method of silver-modified nickel foam is as follows: First, nickel foam (25mm×25mm×1.2mm) is ultrasonically treated in acetone for 20 minutes, and then... -1 The nickel foam was soaked in HNO3 aqueous solution for 5 min, and then washed with a large amount of deionized water. Then, using the nickel foam as the cathode and a platinum sheet electrode as the anode, a solution containing 0.3 mmol·L⁻¹ was applied. -1 AgNO3 and 0.1 mol·L -1 The aqueous solution of HNO3 is used as the cathode electrolyte, containing 0.5 mol·L⁻¹. -1 An aqueous solution of Na₂SO₄ was used as the anolyte, and an application of 0.1 A·cm⁻¹ was applied. -2 Electrodeposition was performed at a current density to obtain nickel foam loaded with palladium (Ag / Ni).

[0067] Comparative Example 5: Electrochemical hydrogenation and dechlorination reaction of tetrachloromethane in tap water

[0068] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru-modified nickel foam as the cathode (3×4cm) 2 Ru content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L tetrachloromethane + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of tetrachloromethane in the tap water was 84.5%, the methane yield was 59.3%, and the methane selectivity was 70.2%.

[0069] This comparative example illustrates that the Ru-modified nickel foam catalytic cathode exhibits far less activity and dehalogenation selectivity for the electrochemical hydrogenation and dechlorination of tetrachloromethane compared to trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, trichloromethane, and monobromodichloromethane.

[0070] Comparative Example 6: Electrochemical hydrogenation and dechlorination reaction of tetrachloroethane in tap water

[0071] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Pt-modified nickel foam as the cathode (3×4cm) 2 Pt content 1 mg / cm³ 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L tetrachloroethane + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V. A silver / silver chloride reference electrode (saturated potassium chloride aqueous solution) was used. After 60 min of reaction, the conversion rate of tetrachloroethane in the tap water was 86.7%, the methane yield was 62.2%, and the methane selectivity was 71.7%.

[0072] This comparative example illustrates that the Pt-modified nickel foam catalytic cathode exhibits far less activity and dehalogenation selectivity for the electrochemical hydrogenation and dechlorination of tetrachloroethane compared to trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, trichloromethane, and monobromodichloromethane.

[0073] Comparative Example 7: Electrochemical hydrogenation and dechlorination reaction of 2,4,6-trichlorophenol in tap water

[0074] Using an H-type electrolytic cell as the reactor, a Nafion 324 membrane as the diaphragm, and Ru-modified nickel foam as the cathode (3×4cm) 2 Ru content 1 mg / cm 2 ), iridium oxide-modified titanium as the anode (2×4cm) 2 Iridium oxide content: 1.25 mg / cm³ 2 50 mL of 5 mM sodium sulfate aqueous solution was used as the anolyte, and 50 mL of tap water containing 3 mg / L 2,4,6-trichlorophenol + 2 mM sodium sulfate (pH = 7.2, temperature = 25℃) was used as the catholyte. The cathode potential was controlled at -0.5 V vs. a silver / silver chloride reference electrode (saturated potassium chloride aqueous solution). After 60 min of reaction, the conversion rate of 2,4,6-trichlorophenol in the tap water was 86.8%, the phenol yield was 2.1%, and the phenol selectivity was 2.4%.

[0075] This comparative example illustrates that the Ru-modified nickel foam catalytic cathode exhibits significantly lower electrochemical hydrogenation dechlorination activity and dehalogenation selectivity for 2,4,6-trichlorophenol compared to trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, trichloromethane, and monobromodichloromethane.

Claims

1. A method for electrocatalytic hydrogenation dehalogenation of haloacetic acid or halomethane in water, characterized in that, The method uses a conductive material surface-modified with ruthenium or platinum as a catalytic electrode and water as a hydrogen source to electrochemically hydrogenate and dehalogenate haloacetic acids or halomethanes in water into acetic acid or methane. The conductive material can be a metal or a carbon material; the metal material can be nickel, titanium, copper, silver, or stainless steel, and the carbon material can be carbon paper, activated carbon, carbon fiber, graphite felt, or foamed glassy carbon. The ruthenium or platinum content is 0.1-3 mg / cm² based on the surface area of ​​the conductive material. 2 The haloacetic acid is trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, tribromoacetic acid, dibromoacetic acid, or monobromoacetic acid; the halomethane is trichloromethane, dichloromethane, monochloromethane, monobromodichloromethane, tribromomethane, or dibromochloromethane.

2. The method as described in claim 1, characterized in that, The electrodes are Ru / Ni, Ru / stainless steel, Ru / graphite felt, Ru / C / carbon paper, Ru / Al2O3 / carbon paper, Pt / Ni, Pt / stainless steel, and Pt / graphite felt.

3. The method as described in claim 1, characterized in that, The reaction temperature range for the electrochemical hydrogenation dehalogenation is 5~90℃.

4. The method as described in claim 1, characterized in that, The concentration range of haloacetic acid or halomethane in the water is 10 μg / L to 1 g / L.

5. The method as described in claim 1, characterized in that, The water bodies include drinking water, surface water, or groundwater.

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