A method for improving the descaling efficiency of cathode materials for electrochemical softening technology

Abstract

The application belongs to the technical field of water treatment and relates to a method for improving the descaling efficiency of a cathode material for electrochemical softening technology, which uses three-dimensional foamed nickel as a substrate and fuel of a fire source as a carbon source to grow carbon nanotubes on the surface of the foamed nickel by means of flame calcination, so as to improve the specific surface area of the foamed nickel, and meanwhile, in order to improve the electrochemical stability of the carbon nanotubes, the instantaneous high temperature provided by a pulse electric flash reactor is used to quickly improve the structural order degree of the carbon nanotubes, so that the service life of the carbon nanotubes in the electrochemical water softening process is prolonged under the premise of ensuring the descaling efficiency.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and relates to a method for improving the descaling efficiency of cathode materials used in electrochemical softening technology. Background Technology

[0002] Ca in water 2+ Mg 2+ Scale-forming ions easily deposit and accumulate at the interface between water and solids, forming scale. This scale can cause blockage and corrosion of metal components in pipes, leading to a decrease in the efficiency of operating units, increased energy consumption, material leakage, production stagnation, and many other problems. Electrochemical softening technology, as a green and environmentally friendly active descaling technology, can precipitate scale-forming ions in solid form without the addition of chemical agents. Its principle is based on the generation of hydroxide ions in the cathode region during water electrolysis. Bicarbonate ions in the water overcome the electric field and migrate to the cathode surface region, combining with hydroxide ions to form carbonate ions. Subsequently, calcium ions are precipitated as calcium carbonate; magnesium ions directly react with hydroxide ions to form magnesium hydroxide precipitate. For example, CN114835199A discloses an electrochemical descaling method, which includes the following steps: 1) preheating industrial circulating water; 2) passing the preheated industrial circulating water between the cathode and anode plates; 3) connecting the cathode and anode plates to the negative and positive terminals of a DC power supply, respectively; 4) turning on the DC power supply, adjusting the current density, and performing electrochemical descaling; 5) replacing the cathode plate when the voltage between the cathode and anode increases to 1.5 times the initial voltage. Therefore, the specific surface area of ​​the cathode, as the attachment site for deposits such as calcium carbonate, determines the scaling rate. However, currently commonly used cathode electrode materials are stainless steel, cast iron, and carbon steel, whose two-dimensional planar structure provides limited deposition area. Therefore, it is necessary to develop three-dimensional cathode electrode materials with high specific surface area to provide a larger reaction area for the electrochemical softening process, thereby improving the deposition rate and descaling efficiency. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a method for improving the descaling efficiency of cathode materials used in electrochemical softening technology.

[0004] To achieve the above-mentioned objectives, the present invention provides a process for improving the descaling efficiency of cathode materials used in electrochemical softening technology as follows:

[0005] (1) Calcine the nickel foam under a heat source until the surface turns black;

[0006] (2) Place the calcined nickel foam in a pulsed electric flash reactor, fix the two ends of the calcined nickel foam with graphite clamps, and apply a current of 30-100A to the two ends of the graphite clamps and keep it constant for 2-10s to obtain the nickel foam cathode.

[0007] (3) Three foamed nickel cathodes and three ruthenium-coated titanium electrode anodes are fixed on the wall of the electrochemical reactor by slots; the foamed nickel cathodes and ruthenium-coated titanium electrode anodes are connected to the negative and positive terminals of the DC power supply by wires.

[0008] (4) Dissolve 15 mol CaCl2 and 30 mol NaHCO3 in 600 L of tap water and let it stand for 1 h. Then use it as the water source for the electrochemical softening process. The water source is fed into the electrochemical reactor by a peristaltic pump and overflows from the outlet at the top. Turn on the DC power supply to remove scale.

[0009] As a further technical solution of the present invention, the thickness of the nickel foam in step (1) is 1 mm and the calcination time is 2-600 s.

[0010] As a further technical solution of the present invention, the fire source in step (1) is selected from an alcohol lamp or a flame gun that burns butane gas.

[0011] As a further technical solution of the present invention, the thickness of the ruthenium-based coated titanium electrode anode in step (3) is 1 mm.

[0012] As a further technical solution of the present invention, the size of the cathode and anode of the foamed nickel cathode and the ruthenium-coated titanium electrode anode in step (3) is 100mm×100mm, and the spacing is 10mm.

[0013] As a further technical solution of the present invention, the volume of the electrochemical reactor in step (3) is 1L.

[0014] As a further technical solution of the present invention, the water inflow rate of the water source in step (4) is 0.4 L / min, and the DC power supply is 100 A / m. 2 The constant current mode.

[0015] Compared with existing technologies, this invention uses three-dimensional nickel foam as a substrate and fuel from an ignition source as a carbon source. It grows carbon nanotubes on the surface of nickel foam by flame calcination, thereby increasing the specific surface area of ​​the nickel foam. At the same time, in order to improve the electrochemical stability of carbon nanotubes, the instantaneous high temperature provided by the pulsed electric flash evaporation reactor is used to rapidly improve the structural order of carbon nanotubes, thereby extending their service life in the electrochemical water softening process while ensuring descaling efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the descaling process of the present invention.

[0017] Figure 2 This is a graph showing the change in total hardness of the effluent over time in Embodiment 1 of the present invention.

[0018] Figure 3This is a graph showing the change in total hardness of the effluent over time in Comparative Example 1 of this invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments.

[0020] Example 1:

[0021] In this embodiment, nickel foam (1 mm thick) is first calcined in the inner flame of an alcohol lamp for 600 seconds until the surface turns black. The calcined nickel foam is then placed in a pulsed electrostatic evaporation reactor. After fixing both ends of the calcined nickel foam with graphite clamps, a 30A anode is applied to both ends of the graphite clamps and held constant for 10 seconds to obtain a nickel foam cathode. The resulting nickel foam cathodes (3 pieces) and ruthenium-coated titanium electrode anodes (3 pieces, 1 mm thick) are then fixed to the wall of the electrochemical reactor using slots. The dimensions of both the nickel foam cathodes and ruthenium-coated titanium electrode anodes are 100 mm × 100 mm, with a spacing of 10 mm. Finally, the nickel foam cathodes and ruthenium-coated titanium electrode anodes are connected to the negative and positive terminals of a DC power supply via wires. When the device is running, water is pumped into the electrochemical reactor by a peristaltic pump and overflows from the top outlet. The water inflow rate is 0.4 L / min. The DC power supply is set to constant current mode (100 A / min). 2 The water hardness at the outlet was measured every hour, and the results were as follows: Figure 2 As shown, the stable value after 5 hours was 16.0 mmol / L. The test was stopped after 24 hours. The precipitate on the cathode surface was knocked off, collected, and weighed. The precipitation rate was calculated to be 658.8 g / (m²). 2 h), the descaling efficiency is 54.9%.

[0022] Example 2:

[0023] In this embodiment, nickel foam (1 mm thick) is first calcined under a blowtorch for 5 seconds until the surface turns black. The calcined nickel foam is then placed in a pulsed electrostatic evaporation reactor. After fixing both ends of the calcined nickel foam with graphite clamps, a 40A anode is applied to both ends of the graphite clamps and held constant for 2 seconds to obtain a nickel foam cathode. The resulting nickel foam cathodes (3 pieces) and ruthenium-coated titanium electrode anodes (3 pieces, 1 mm thick) are then fixed to the wall of the electrochemical reactor using slots. The dimensions of the nickel foam cathodes and ruthenium-coated titanium electrode anodes are 100 mm × 100 mm, with a spacing of 10 mm. The nickel foam cathodes and ruthenium-coated titanium electrode anodes are then connected to the negative and positive terminals of a DC power supply via wires. When the device is running, water is pumped into the electrochemical reactor by a peristaltic pump and overflows from the top outlet. The water inflow rate is 0.4 L / min. The DC power supply is set to constant current mode (100 A / min). 2The water hardness at the outlet was measured every hour. After 5 hours, the stable value was 18.5 mmol / L. After 24 hours, the test was stopped, and the precipitate on the cathode surface was knocked off, collected, and weighed. The sedimentation rate was calculated to be 512.4 g / (m³). 2 h), the descaling efficiency is 42.7%.

[0024] Comparative Example 1:

[0025] In this comparative example, three ordinary foamed nickel cathodes and three ruthenium-coated titanium electrode anodes (1 mm thick) were fixed to the wall of an electrochemical reactor using slots. The ordinary foamed nickel cathodes and ruthenium-coated titanium electrode anodes were 100 mm × 100 mm in size and spaced 10 mm apart. The foamed nickel cathodes and ruthenium-coated titanium electrode anodes were connected to the negative and positive terminals of a DC power supply, respectively, via wires. During operation, water was pumped into the electrochemical reactor by a peristaltic pump and overflowed from the top outlet at a rate of 0.4 L / min. The DC power supply was set to constant current mode (100 A / m). 2 The water hardness at the outlet was measured every hour, and the results were as follows: Figure 3 As shown, the stable value after 5 hours was 25.6 mmol / L. The test was stopped after 24 hours. The precipitate on the cathode surface was knocked off, collected, and weighed. The precipitation rate was calculated to be 372.0 g / (0.32m). 2 h), the descaling efficiency is 31.0%.

[0026] Comparative Example 2:

[0027] In this comparative example, nickel foam (1 mm thick) was first calcined under a blowtorch for 5 seconds until the surface turned black. The resulting nickel foam cathodes (3 pieces) and ruthenium-coated titanium electrode anodes (3 pieces, 1 mm thick) were then fixed to the wall of an electrochemical reactor using slots. The nickel foam cathodes and ruthenium-coated titanium electrode anodes were 100 mm × 100 mm in size, with a spacing of 10 mm. Subsequently, the nickel foam cathodes and ruthenium-coated titanium electrode anodes were connected to the negative and positive terminals of a DC power supply, respectively, using wires.

[0028] When the device is running, water is fed into the electrochemical reactor by a peristaltic pump and overflows from the top outlet at a rate of 0.4 L / min. The DC power supply is set to constant current mode (100 A / m). 2 The water hardness at the outlet was measured every hour, and the stable value after 5 hours was 13.8 mmol / L. After 24 hours, the test was stopped, the precipitate on the cathode surface was knocked off and collected, and weighed. The sedimentation rate was calculated to be 459.6 g / (m³). 2 h), the descaling efficiency is 38.3%.

[0029] Comparative Example 3:

[0030] In this comparative example, nickel foam (1 mm thick) was first calcined in the inner flame of an alcohol lamp for 600 s until the surface turned black. It was then placed in a pulsed electrostatic evaporation reactor. The calcined nickel foam was fixed at both ends using graphite clamps, and a current of 100 A was applied to both ends of the clamps and held constant for 10 s. The resulting nickel foam cathodes (3 pieces) and ruthenium-coated titanium electrode anodes (3 pieces, 1 mm thick) were then fixed to the wall of the electrochemical reactor using slots. The nickel foam cathodes and ruthenium-coated titanium electrode anodes were 100 mm × 100 mm in size, with a spacing of 10 mm. The nickel foam cathodes and ruthenium-coated titanium electrode anodes were then connected to the negative and positive terminals of a DC power supply, respectively, via wires. During operation, water was pumped into the electrochemical reactor by a peristaltic pump and overflowed from the top outlet at a rate of 0.4 L / min. The DC power supply was set to constant current mode (100 A / min). 2 The water hardness at the outlet was measured every hour, and the stable value after 5 hours was 22.8 mmol / L. After 24 hours, the test was stopped, the precipitate on the cathode surface was knocked off and collected for weighing, and the sedimentation rate was calculated to be 391.2 g / (m³). 2 h), the descaling efficiency is 32.6%.

[0031] The above description of the embodiments is intended to help those skilled in the art understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for improving the descaling efficiency of a cathode material for electrochemical softening technology, characterized in that, The specific process is: (1) calcining the foamed nickel under a fire source until the surface is black; (2) placing the calcined foamed nickel in a pulsed electric flash reactor, fixing the two ends of the calcined foamed nickel with graphite clamps, and applying a current of 30-100 A to the two ends of the graphite clamps for 2-10 s to obtain a foamed nickel cathode; (3) arranging and fixing three foamed nickel cathodes and three ruthenium-based coated titanium electrode anodes through insertion slots on the wall of an electrochemical reactor; connecting the foamed nickel cathodes and the ruthenium-based coated titanium electrode anodes with the negative and positive poles of a direct current power source through wires, respectively; (4) dissolving 15 mol CaCl2 and 30 mol NaHCO3 in 600 L tap water, standing for 1 h, and then using the water as a water source for the electrochemical softening process; inputting the water source into the electrochemical reactor by a peristaltic pump and overflowing from the top outlet; and opening the direct current power source to remove scale.

2. The method of claim 1, wherein the method is characterized by, The foamed nickel in step (1) has a thickness of 1 mm, and the calcination time is 2-600 s.

3. The method of claim 2, wherein the method is characterized by, The fire source in step (1) is selected from one of an alcohol lamp or a butane gas burning spray gun.

4. The method of claim 3, wherein the method is characterized by, The thickness of the ruthenium-based coated titanium electrode anode in step (3) is 1 mm.

5. The method of claim 4, wherein the method is characterized by: The size of the cathode and anode of the foamed nickel cathode and the ruthenium-based coated titanium electrode anode in step (3) is 100 mm×100 mm, and the spacing is 10 mm.

6. The method of claim 5, wherein the method is characterized by, The volume of the electrochemical reactor in step (3) is 1 L.

7. The method of claim 6, wherein the method is characterized by, The water source of step (4) has an inflow rate of 0.4 L / min, and the direct current power supply is 100 A / m 2 in a constant current mode.

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