Sewage treatment electro-catalysis electrode material and preparation method thereof

Abstract

The application belongs to the technical field of electrode material preparation and electrocatalytic wastewater treatment, and specifically provides a sewage treatment electrocatalytic electrode material, a preparation method thereof and application thereof in sewage treatment. The preparation method of the electrocatalytic electrode material is as follows: a zinc nitrate solution, a cobalt nitrate anhydrous methanol solution A and a 2-methyl imidazole anhydrous methanol solution B are configured, the A and B solutions are mixed and then subjected to a solvothermal reaction in an oven to obtain Co1 / Zn2-ZIF-8, the Co1 / Zn2-ZIF-8 is mixed with carboxymethyl cellulose and then subjected to freeze drying to obtain aerogel, and the aerogel is subjected to sulfuration in a tube furnace in an inert gas atmosphere to obtain the electrocatalytic electrode material. The electrocatalytic electrode material prepared by the method has the advantages of simple preparation method, low raw material cost and wide application prospect in the field of sewage treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater electrode material preparation, specifically to a method for preparing a Co9S8 / ZnS modified three-dimensional carbon-based aerogel electrocatalytic electrode and its application in electrocatalytic wastewater treatment. Background Technology

[0002] With continuous social development, large-scale industrialization and urbanization have led to the pollution of groundwater and other freshwater resources by organic wastewater. Organic wastewater generally contains organic pollutants such as pesticides, pharmaceutical waste, nitro aromatic compounds, and dyes. The decomposition of these organic pollutants causes aquatic organisms to die due to lack of oxygen, damaging the aquatic ecosystem. Wastewater with excessively high COD (chemical oxygen demand) should not be directly discharged.

[0003] Therefore, with the increasing awareness of environmental protection, the efficient degradation of organic pollutants in wastewater has received growing attention in the field of environmental protection. At the same time, raising wastewater discharge standards, reducing the organic content of wastewater, and creating a safe and stable ecological environment are crucial.

[0004] Transition metal sulfide electrode materials possess advantages such as good conductivity, good catalytic effect, and economy, and have great application prospects. Currently, there is much research on transition metal sulfide materials, but most electrode materials suffer from problems such as poor stability, poor mass transfer, high energy consumption, and low efficiency in treating COD and nitrogenous substances in wastewater. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an electrocatalytic electrode material for wastewater treatment and its preparation method.

[0006] To address the problems existing in the prior art, a Co9S8 / ZnS modified three-dimensional carbon-based aerogel is prepared by selecting a three-dimensional carbon material as the matrix material. The synergistic effect of Co9S8 / ZnS improves the catalytic performance of the material, and the three-dimensional carbon-based aerogel, as the substrate material, enhances the stability of the product and improves mass transfer and electron transport channels. To achieve the above objectives, according to the present invention, a method for preparing a Co9S8 / ZnS modified three-dimensional carbon-based aerogel electrocatalytic electrode is characterized by the following preparation steps:

[0007] (1) Prepare a certain proportion of a mixed methanol solution A of cobalt nitrate hydrate and zinc nitrate hydrate and an anhydrous methanol solution B of 2-methylimidazole, mix and stir evenly, and carry out a solvothermal reaction in an oven to obtain Co1 / Zn2-ZIF-8.

[0008] (2) Co1 / Zn2-ZIF-8 was mixed with carboxymethyl cellulose and freeze-dried to obtain an aerogel;

[0009] (3) Sulfidation was carried out in a tubular furnace containing a sulfur source to obtain Co9S8 / ZnS / NC.

[0010] Preferably, the sulfur source in step (3) of the present invention is elemental sulfur.

[0011] More preferably, in step (1), the mass ratio of zinc to cobalt in liquid A is (0.3-2:0.3-1), with the optimal ratio being 2:1.

[0012] More preferably, in step (1), the reaction time is 10-16h, with an optimal value of 12h, and the heating temperature is 90-120℃, with an optimal value of 100℃.

[0013] More preferably, in step (2), the volume ratio of water to acetone is (15-25:0.5-3), with an optimal ratio of 20:1, and the mixing and stirring time of the Co1 / Zn2-ZIF-8 solution and the CMC solution is 3-6 hours, with an optimal ratio of 2 hours.

[0014] In a further preferred embodiment, the inert gas used in step (3) of the above-mentioned wastewater treatment electrocatalytic electrode material and its preparation method is nitrogen or argon, preferably nitrogen; the heating rate of the tube furnace is 2-5℃ / min, preferably 5℃ / min; the first stage of sulfidation temperature is 150-300℃, preferably 300℃; the second stage of sulfidation temperature is 500-600℃, preferably 600℃; the first stage of sulfidation time is 2-3h, preferably 2 hours; the second stage of sulfidation time is 3-6h, preferably 3 hours.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects:

[0016] The Co9S8 / ZnS modified three-dimensional carbon-based aerogel electrocatalytic electrode prepared by this invention has a three-dimensional structure and is a novel three-dimensional electrode material. It has good mass transfer and electron transport channels, good conductivity, large specific surface area, and the characteristics of improved catalytic activity by the synergistic effect of bimetallic sulfides.

[0017] This invention utilizes a Co9S8 / ZnS-modified three-dimensional carbon-based aerogel electrocatalytic electrode, which features a simple, low-cost, environmentally friendly, and high-yield process suitable for commercialization.

[0018] The Co9S8 / ZnS modified three-dimensional carbon-based aerogel electrocatalytic electrode prepared by this invention showed a significant improvement in organic matter degradation efficiency under the same conditions in practical performance tests, with a degradation rate of over 95% within 30 minutes. Detailed Implementation

[0019] Example 1:

[0020] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0021] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0022] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace. Under a nitrogen atmosphere, heat the furnace to 300 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0023] Example 2:

[0024] (1) Dissolve 0.4343 g of Zn(NO3)2·6H2O and 0.1419 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring. After stirring evenly, transfer the mixed solution to a 100 mL high-pressure autoclave with a polytetrafluoroethylene liner. After sonication for 15 min, maintain at 100 °C for 12 h. Then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0025] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0026] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace. Under a nitrogen atmosphere, heat the furnace to 300 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0027] Example 3:

[0028] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0029] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0030] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace in sequence. Under a nitrogen atmosphere, heat the furnace to 300 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 3 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0031] Example 4:

[0032] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0033] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0034] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace in sequence. Under a nitrogen atmosphere, heat the furnace to 300 °C at 3 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0035] Example 5:

[0036] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0037] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0038] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 50 mg of aerogel in a tube furnace. Under a nitrogen atmosphere, heat the furnace to 300 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0039] Example 6:

[0040] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0041] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0042] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace. Under a nitrogen atmosphere, heat the furnace to 250 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0043] Example 7:

[0044] (1) Dissolve 0.3921 g of Zn(NO3)2·6H2O and 0.1917 g of Co(NO3)2·6H2O in 15 mL of anhydrous methanol to obtain solution A. Dissolve 1.297 g of 2-methylimidazole in 15 mL of anhydrous methanol to obtain solution B. Add solution B to solution A with stirring, stir evenly, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, sonicate for 15 min, maintain at 100 °C for 12 h, then cool to room temperature, centrifuge, wash 3 times, and vacuum dry to obtain Co1 / Zn2-ZIF-8.

[0045] (2) Co1 / Zn2-ZIF-8 powder (0.9 g) was dispersed in water / acetone (10 mL / 0.5 mL) and sonicated for 2 hours to form a homogeneous solution. Carboxymethyl cellulose (CMC, 0.1 g) was dispersed in water (10 mL) at 80 °C with stirring, and then stirred at room temperature for 3 hours to form a homogeneous gel solution. The prepared Co1 / Zn2-ZIF-8 solution was mixed with the CMC solution and stirred for 3 hours, and then sonicated for 3 hours. The Co1 / Zn2-ZIF-8 / CMC hydrogel was frozen at –20 °C for 12 hours and then freeze-dried under vacuum for 48 hours to obtain Co1 / Zn2-ZIF-8 / CMC aerogel.

[0046] (3) Place a ceramic boat containing 500 mg of sublimed sulfur and a ceramic boat containing 100 mg of aerogel in a tube furnace in sequence. Under a nitrogen atmosphere, heat the furnace to 200 °C at 5 °C / min and hold for 2 h. Then heat the furnace to 600 °C at 5 °C / min and hold for 4 h to obtain Co9S8 / ZnS / NC.

[0047] Experimental Example

[0048] Prepare 5.5L of laboratory-simulated organic wastewater containing ammonia nitrogen or amino acids, with an initial COD of 240mg / L and total nitrogen of 62mg / L.

[0049] A Co9S8 / ZnS / NC-modified glassy carbon electrode was used as the cathode, and a platinum electrode was used as the anode. A constant current mode was employed, with an effective electrode area of ​​5.31 cm². 2 The current density is 26.7 mA·cm. -2 .

[0050] Electrochemical wastewater treatment: Inject 0.05M NaCl electrolyte and 0.5L of the simulated organic wastewater prepared above into the electrolytic cell, electrolyze for 0.5 hours. Within 30 minutes, the wastewater meets the emission standard of COD below 30mg / L, with a degradation efficiency of up to 87.5%, and the total nitrogen after wastewater treatment is 10.5mg / L.

[0051] Using the same simulated organic wastewater prepared above, an unmodified glassy carbon electrode was used as the cathode and a platinum electrode as the anode for electrochemical wastewater treatment. A constant current mode was also employed, with an effective electrode area of ​​5.31 cm². 2 The current density is 26.7 mA·cm. -2 .

[0052] An electrolyte of 0.05M NaCl and 0.5L of organic wastewater were injected into an electrolytic cell, and electrolysis was carried out for 2 hours. The corresponding discharge standard for this wastewater is COD of 186mg / L, COD degradation efficiency of 22.5%, and total nitrogen of 53.2mg / L after treatment.

[0053] Furthermore, a glassy carbon electrode modified with a Co9S8 / N-CCA composite electrode was used as the cathode. The Co9S8 / N-CCA composite electrode was prepared using the method disclosed in patent CN112169824A, with a platinum electrode as the anode. A constant current mode was also employed. The effective electrode area was 5.31 cm². 2 The current density is 26.7 mA·cm. -2 .

[0054] An electrolyte of 0.05M NaCl and 0.5L of organic wastewater were injected into an electrolytic cell, and electrolysis was carried out for 2 hours. The corresponding discharge standard for this wastewater is COD of 142mg / L, COD degradation efficiency of 40.8%, and total nitrogen of 38mg / L after treatment.

[0055] The above detailed description of an electrocatalytic electrode material for wastewater treatment and its preparation method, with reference to the embodiments, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing an electrocatalytic electrode material for wastewater treatment, characterized in that, The preparation steps are as follows: (1) Prepare a mixed methanol solution A of cobalt nitrate hexahydrate and zinc nitrate hexahydrate and an anhydrous methanol solution B of 2-methylimidazole, mix and stir evenly, and carry out a solvothermal reaction in an oven to obtain Co1 / Zn2-ZIF-8. (2) The obtained Co1 / Zn2-ZIF-8 was mixed with carboxymethyl cellulose and freeze-dried to obtain an aerogel; (3) Sulfidation was carried out in a tubular furnace containing a sulfur source to obtain Co9S8 / ZnS / NC; The heating rate of the tubular furnace is 2-5℃ / min, the holding temperature of the first stage of vulcanization is 150-300℃, the holding temperature of the second stage is 500-600℃, and the holding time is 2-3h for the first stage and 3-6h for the second stage.

2. The method for preparing an electrocatalytic electrode material for wastewater treatment according to claim 1, characterized in that, The sulfur source in step (3) is elemental sulfur.

3. The method for preparing an electrocatalytic electrode material for wastewater treatment according to claim 1, characterized in that, In step (1), the mass ratio of zinc nitrate hexahydrate and cobalt nitrate hexahydrate in solution A is 0.3-2:0.3-1.

4. The method for preparing an electrocatalytic electrode material for wastewater treatment according to claim 1, characterized in that, In step (1), the reaction time is 10-16 h and the heating temperature is 90-120 °C.

5. The application of the wastewater treatment electrocatalytic electrode material prepared by any one of claims 1 to 4 in wastewater treatment, characterized in that, The electrode material reduces nitrogen-containing organic matter, organochlorides, and heavy metal compounds in wastewater.