An electrochemical electrode system and uses thereof, electrochemical systems and uses thereof and methods for removing water hardness

Abstract

The present application relates to a kind of electrochemical electrode system and its use, electrochemical system and its use and method for removing water hardness.The electrochemical electrode system and electrochemical system of the present application, including cathode and anode, the shape of the cathode is conical cylinder, and a plurality of through holes are formed on wall;The anode is composed of the conductive particle filler filled in the conical cylinder cathode;The side of the cathode and the particle filler of anode contact with anode is insulated.The electrode of the present application changes the traditional electrode configuration and electrode placement mode, selects special conical cylinder cathode and particle anode, and fills particle anode in conical cylinder cathode, and the design can infinitely small shorten electrode spacing to reduce energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical water treatment, in particular to an electrochemical electrode system and its use, an electrochemical system and its use and method for removing water hardness. BACKGROUND

[0002] Once the concentration of calcium and magnesium ions in industrial wastewater exceeds its solubility limit, it will scale on the surface of the material in contact with it, which will cause serious technical and economic consequences. Specifically, the formation of an insulating scale layer can block the pipes of the water delivery system, worsen the efficiency of the heat exchangers of the cooling tower and the boiler, and cause membrane scaling and flux decline in some membrane systems for treating wastewater. Therefore, it is urgent to remove hardness ions in industrial wastewater to reduce the adverse effects of scaling. During the softening process, calcium and magnesium ions in industrial wastewater are mainly removed in the form of CaCO3 and Mg(OH)2 crystallization. The widely used chemical method currently uses chemicals such as lime, slaked lime, and sodium hydroxide to increase the pH value of the wastewater. However, the large amount of chemicals added in this process not only introduces exogenous ions but also produces a large amount of sludge that is difficult to dispose of, greatly increasing the subsequent treatment cost.

[0003] In recent years, electrochemical treatment has been considered as an environmentally friendly water softening technology. The existing cathodic deposition hardness removal technology utilizes the OH - The liquid film on the cathode surface is enriched to form a strong alkaline region, which promotes the conversion of HCO3 - to CO3 2- in water, accelerates the deposition of calcium and magnesium ions on the cathode surface, and thus achieves water softening. However, since OH - is only concentrated in a thin layer on the cathode surface, the water softening region is limited to the cathode surface, making the cathode bear the dual functions of alkali production and scaling, which increases the energy consumption of the reaction while reducing the production of OH - The alkaline environment produced during electrochemical softening is a necessary condition for the deposition of hardness ions. The addition of a diaphragm between the anode and the cathode can effectively inhibit the occurrence of acid-base neutralization reactions, increase the strong alkaline region, promote the deposition of calcium and magnesium in the bulk solution, reduce the demand for cathode area, and improve the hardness removal efficiency. However, the presence of the diaphragm will greatly increase the energy consumption of the reaction, in addition, the deposition of scale on the membrane surface will also cause membrane fouling and other problems. Furthermore, whether it is cathodic deposition hardness removal or diaphragm electrolysis hardness removal system, a larger anode-cathode spacing will increase the voltage, resulting in increased energy consumption. SUMMARY

[0004] To solve the above problems, the application provides an electrochemical electrode system, which comprises a cathode and an anode, the cathode is in the shape of a conical cylinder, and a plurality of through holes are formed on the wall of the cathode; the anode is composed of conductive particle fillers filled in the conical cylinder-shaped cathode; and the side of the cathode, which is in contact with the particle fillers of the anode, is insulated from the anode.

[0005] On the basis of the above scheme, the material of the cathode is titanium, carbon steel or stainless steel.

[0006] On the basis of the above scheme, the holes on the wall of the cathode are formed by punching, laser drilling or metal wire weaving.

[0007] On the basis of the above scheme, the conductive particle fillers are one or a combination of diamond particles, Ti4O7 particles, carbon-based particles and titanium particles.

[0008] On the basis of the above scheme, the insulation method is:

[0009] insulating treatment is performed on the inner surface of the cathode by spraying plastic insulation material,

[0010] insulating treatment is performed on the inner surface of the cathode by coating or dipping insulation paint

[0011] or

[0012] a layer of insulation material net is added between the cathode and the anode.

[0013] The electrochemical electrode system described above in the application is applied in an electrochemical system for removing water hardness or a method for removing water hardness.

[0014] The application also provides an electrochemical system for removing water hardness, which comprises the electrochemical electrode system described above and further comprises a reaction tank; the bottom of the anode of the electrochemical electrode system is provided with a water outlet connected to the outside of the reaction tank.

[0015] On the basis of the above scheme, the reaction tank is further provided with a water pumping and filtering device for pumping water in the cathode chamber to the anode chamber during electrolysis, and the inlet end of the water pumping and filtering device is provided with a filtering device for intercepting precipitated particles in the cathode chamber.

[0016] The electrochemical system described above is applied in the removal of water hardness.

[0017] Based on the electrochemical system described above, the application also provides a method for removing water hardness.

[0018] Compared with the prior art, the application has the following beneficial effects:

[0019] (1) The traditional electrode configuration and electrode placement method have been changed. A special conical cathode and granular anode have been selected. The granular anode is filled in the conical cathode. This design can shorten the electrode spacing to an infinitesimal extent to reduce energy consumption.

[0020] (2) An "asymmetric electrode" is used. By insulating the inner surface of the cathode, the electrolysis reaction mainly occurs on the back side of the electrode. Furthermore, due to the certain tilt angle of the conical electrode, the hydrogen bubbles generated by electrolysis on the back side of the asymmetric cathode can easily and rapidly move upward, carrying away the OH- ions generated on the back side of the cathode. - The particle electrodes packed inside the cathode will simultaneously generate H. + The ions flow out of the reactor from the bottom due to the downward seepage of water inside the packed bed (anode) and the flushing effect of the water entering from the top, thereby suppressing H+ at the junction of the cathode and anode. + With OH - Neutralization reaction;

[0021] (3) The filter device is placed in situ in the reaction tank to achieve rapid separation of crystals in alkaline water, and the filtered water is passed into the three-dimensional anode packing bed to neutralize the alkaline water, remove residual alkalinity in the water, and improve scale inhibition efficiency. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the electrode system in Embodiment 1 of this application;

[0024] Figure 2 for Figure 1 A magnified structural diagram of part A in the middle;

[0025] Figure 3 This is a schematic diagram of the electrochemical system in Example 2 of this application;

[0026] Figure 4 The graph shows the results of water hardness removal efficiency and outlet pH changes under different influent flow rates in Example 1.

[0027] Figure 5 The graph shows the results of water hardness removal efficiency and outlet pH changes when using the water pumping and filtration device in Example 2 at different pumping flow rates.

[0028] Figure 6The water hardness removal efficiency and the pH value change of the outlet water under different current densities in use example 3 are shown in the following figures:

[0029] Figure 7 The energy consumption of water hardness removal under different current densities in use example 4 is shown in the following figure. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] Embodiment 1

[0032] As shown in Figure 1 and 2 , the present application provides an electrochemical electrode system, which comprises a cathode 1 and an anode 2; the shape of the cathode 1 is a conical cylinder, and a plurality of through holes are formed on the wall; the anode 2 is composed of conductive particle fillers filled in the conical cylinder-shaped cathode 1; the side of the cathode 1 in contact with the particle fillers of the anode 2 is insulated from the anode 1, and in use, the conical cylinder-shaped cathode 1 has a large opening downward and a small opening upward.

[0033] In use, the cathode 1 is connected to the negative electrode of the power supply, and the anode 2 is connected to the positive electrode of the power supply.

[0034] The electrode system can infinitely shorten the electrode spacing between the cathode 1 and the anode 2, so as to reduce the energy consumption. The actual electrode spacing is only the thickness of the insulating material during the insulation process.

[0035] By adopting this “asymmetric electrode” (the cathode is a conical cylinder, and the anode is a circular truncated cone), and by insulating the inner surface (which can also be referred to as the “front surface”, which refers to the surface in contact with the anode) of the cathode, the electrolysis reaction mainly occurs on the outer surface (which can also be referred to as the “back surface”, which refers to the surface away from the anode) of the electrode. In addition, the conical cathode 1 has a certain inclination angle, so that during electrolysis, the hydrogen bubbles generated by the electrolysis of the back surface of the asymmetric cathode 1 move upward quickly, carrying away the OH - .

[0036] There are many ways to insulate the cathode 1 and the anode 2. The present application provides several specific embodiments:

[0037] (1) The inner surface (the side in contact with the anode 2) of the cathode 1 is insulated by spraying plastic, and the spraying material can be acrylic powder, polyester powder, polytetrafluoroethylene powder, etc.;

[0038] (2) Insulation treatment is performed on the inner surface of cathode 1 (the side in contact with anode 2) by coating or impregnating with insulating varnish. Insulating varnish, also called insulating coatings, is a coating with excellent electrical insulation properties. There are many materials that can be used for insulating varnish, such as Teflon coating, diphenyl ether solvent-free insulating varnish, acetal, polyimide insulating varnish, etc., which will not be elaborated here.

[0039] (3) Add an insulating material mesh, such as a nylon mesh, between the cathode 1 and the anode 2 to provide insulation between the cathode 1 and the anode 2. The insulating material mesh can also be cone-shaped and fit against the inner wall of the cathode 1.

[0040] In practical use, the aforementioned electrochemical electrode system can be implemented by first placing cathode 1 into the reaction tank, then filling cathode 1 with anode material, with the inner wall of cathode 1 and the bottom wall of the reaction tank together forming the anode chamber. For example... Figure 1 As shown, another method is to add a base plate 9 to the bottom of the cathode 1, so that the anode chamber is formed by the inner wall of the cathode 1 and the base plate 9.

[0041] As a feasible option, the cathode 1 can be made of materials including, but not limited to, titanium, carbon steel, and stainless steel. The holes on the cathode wall can be formed by physical punching, laser drilling, or wire weaving, with a hole diameter of 1mm-4mm.

[0042] Stainless steel materials include, but are not limited to, 304, 304L, 304N, 316, 316L, and 321.

[0043] As an feasible option, the conductive particle filler used in the anode 2 may be one or a combination of diamond particles, Ti4O7 particles, carbon-based particles and titanium particles.

[0044] The electrochemical electrode system described above can be used to create an electrochemical system for removing hardness from water; it can also be used directly to remove hardness from water.

[0045] like Figure 3 As shown, during use, the water level is lower than the height of anode 2. The height of anode 2 is slightly lower than the height of cathode 1.

[0046] Example 2

[0047] Based on the electrochemical electrode system of Example 1, this application provides an implementation scheme for an electrochemical system for removing water hardness. For example... Figure 3 As shown, in addition to the electrochemical electrode system in Example 1, the electrochemical system also includes a reaction tank 3; the bottom of the anode 2 of the electrochemical electrode system is provided with an outlet 10 that connects to the outside of the reaction tank 3.

[0048] In use, the cathode 1 is connected to the negative pole of the power supply 4 through the wire 5, and the anode 2 is connected to the positive pole of the power supply 4 through the conductive rod 6. In the process of electrolysis, the water body to be treated (hardness water body) is introduced into the cathode chamber (the cathode chamber refers to the chamber between the outer surface of the cathode 1 and the reaction tank 3), and the acidic water body generated by the anode 2 in the electrolysis process is continuously discharged from the bottom of the anode 2, and the alkaline water body generated in the cathode chamber is discharged (for example, by overflow) from the cathode chamber. Overall, the amount of the water body to be treated entering the reaction tank is equal to the total amount of the acidic water body and the alkaline water body discharged.

[0049] The above-mentioned electrochemical system can realize acid-base separation during electrolysis, thereby facilitating the removal of the hardness of the water body. However, the electrochemical system needs to further process the treated alkaline water body to remove the precipitated particles (such as CaCO3 fine particles) in the water body and the alkalinity in the water body. In order to better achieve the removal of the hardness of the water body, based on the above technical solution, a specific embodiment is provided to simultaneously remove the hardness of the water body and the alkalinity in the cathode chamber in the process of electrolysis.

[0050] As shown in Figure 3 , the reaction tank 3 is further provided with a water pumping and filtering device for pumping the water body in the cathode chamber into the anode chamber in the process of electrolysis. The inlet end of the water pumping and filtering device is provided with a filtering device 7 for intercepting the precipitated particles formed in the cathode chamber. Specifically, the water body in the cathode chamber is pumped to the anode chamber by using a pump 8.

[0051] In this way, in the process of electrolysis, the flow rate of the water body to be treated entering the reaction tank 3 is equal to the flow rate of the water flowing out of the reaction tank 3 from the water outlet 10 (i.e., the water body in the cathode chamber does not need to be discharged from the reaction tank 3).

[0052] The purpose of the filtering device 7 is to intercept the CaCO3 fine particles generated in the cathode chamber during electrolysis. Therefore, many filtering devices can be used, such as titanium sintered filter elements, stainless steel sintered filter elements, or hollow fiber membranes.

[0053] The bottom of the reaction tank 3 is provided with a water inlet 11 for inputting the water body to be treated into the reaction tank 3.

[0054] The principle of removing the hardness of the water body by using the electrochemical system with the water pumping and filtering device is as follows: the inner surface of the cathode 1 is insulated, so that the electrolysis reaction mainly occurs on the outer surface of the cathode. The special cathode 1 configuration (conical cylinder) and the porous structure on the wall promote the rapid escape of the bubbles on the surface of the cathode 1 to the bulk solution, inhibit the reaction between OH - and H + generated by the anode, realize membrane-free acid-base separation, and the cross-flow water inlet mode of the system is conducive to the separation of OH- The diffusion into the bulk solution forms a strong alkaline atmosphere in the bulk solution, at this time, the deposition reaction of hardness ions is not limited to the back of the cathode but in the entire bulk solution, thus achieving the effect of efficient removal of water hardness. And the system places a filter device 7 in the device in situ, after the water in the cathode chamber is filtered by the filter device 7, the fine particles such as CaCO3 formed in the cathode chamber can be intercepted, and then accumulated on the surface, and the filtered cathode water enters the anode, which can further reduce the hardness and alkalinity of the water body.

[0055] The above-mentioned electrochemical system for removing water hardness in the embodiment realizes acid-base separation without using a diaphragm by modifying the surface of the electrode and changing the structure of the electrode (using a conical cylinder electrode with a certain inclination), using an "asymmetric" cathode to make the electrolysis reaction mainly occur on the outer surface of the electrode, and the porous conical cylinder electrode is more conducive to the entry of lattice ions in the solution into the electrode / solution interface. The special shape of the "conical cylinder" is also more conducive to the diffusion of substances at the interface into the bulk solution through the escape of bubbles. In addition, the porous structure of the cathode and the movement direction of the water flow controlled by the cross-flow of the anode and cathode into the water are more conducive to reducing the accumulation of bubbles on the electrode, promoting the diffusion of H + and OH - separation, and the insulating property of the positive surface of the cathode enables the particle anode to be directly packed inside the cathode without an external diaphragm, greatly shortening the electrode spacing and significantly reducing the reaction energy consumption without affecting the hardness removal effect. The chemical (ionic) equation of the reaction is:

[0056] O2+2H2O+4e - →4OH -

[0057] 2H2O+2e - →H2+2OH -

[0058] 2H2O+2e - →O2+4H +

[0059] OH - +HCO3 - →CO3 2- +H2O

[0060] Ca 2+ +CO3 2- →CaCO3↓

[0061] Mg 2+ +2OH - →2Mg(OH)2↓

[0062] Example 3

[0063] Based on the electrochemical electrode system of Example 1 or the electrochemical system for removing water hardness of Example 2, the present application provides a specific method for removing water hardness. Specifically:

[0064] During electrolysis, the flow rate of the water body to be treated entering the reaction tank 3 is equal to the flow rate of the water flowing out of the reaction tank 3 from the water outlet 10.

[0065] The residence time of the water to be treated in the reaction tank 3 is controlled to be 1-60 min;

[0066] The current density used in the reaction in the reaction tank 3 is between 1-30 mA / cm 2 .

[0067] Use Example 1

[0068] Analog solution containing calcium hardness (as CaCO3) 300 mg / L, magnesium hardness 100 mg / L, total alkalinity 300 mg / L, Ca 2+ and HCO3 - molar ratio of 1:2, conductivity of 3.5 mS / cm was prepared with anhydrous calcium chloride, magnesium sulfate, sodium bicarbonate, anhydrous sodium sulfate. The electrochemical electrolysis unit uses a conical asymmetric porous stainless steel cathode with a pore size of 1 mm (cathode back electrolysis), a graphite particle anode, which is filled inside the cathode, and a current density of 10 mA / cm 2 . The experiment was carried out under the conditions of water inlet flow rate of 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 250 mL / min, and during the electrolysis process, the cathode crystallization water was extracted from the in-situ porous titanium filter (0.22 μm pore size) inside the device at a certain flow rate and transported to the anode chamber for further removal of hardness and alkalinity. The extraction speed of the titanium filter was 3 / 4 of the water inlet flow rate, and the water outlet 10 at the bottom of the device was used for the solution in the anode chamber to flow out of the reaction tank 3, and the water outlet flow rate was consistent with the water inlet flow rate of the cathode side water inlet 11. The treatment results are shown in Figure 4 . The porous titanium filter refers to a kind of filter device 7.

[0069] As shown in Figure 4 , the calcium hardness removal efficiency decreases with the increase of the water inlet flow rate, because when the water inlet flow rate is too fast, the water body is in a turbulent state, which is not conducive to the separation of acid and alkali, resulting in the decrease of hardness removal efficiency and the increase of the pH value of the effluent. When the water inlet flow rate is 50 ml / min, the hardness removal effect is best, and the final effluent pH value is close to neutral. Considering the water treatment capacity, energy consumption, treatment effect and other aspects, the water inlet flow rate of the subsequent examples is selected as 100 ml / min.

[0070] Use Example 2

[0071] Anhydrous calcium chloride, magnesium sulfate, sodium bicarbonate, anhydrous sodium sulfate were used to prepare simulated feed water containing calcium hardness (as CaCO3) 300 mg / L, magnesium hardness 100 mg / L, total alkalinity 300 mg / L, Ca 2+ HCO3 - The simulated feed water had a molar ratio of 1:2 and a conductivity of 3.5 mS / cm. The electrochemical electrolysis unit used a conical asymmetric porous stainless steel cathode (cathode back electrolysis) with a pore size of 1 mm, a graphite particle anode, and the particle anode was packed inside the cathode. The water inlet flow rate was 100 mL / min, and the current density was 10 mA / cm 2 The experiment was carried out under the condition that the cathode crystallization water was extracted from the in-situ porous titanium filter (0.22 μm pore size) inside the device at a certain flow rate and delivered to the anode chamber to further remove hardness and alkalinity. The extraction speed of the titanium filter was 1 / 3, 1 / 2, 2 / 3, 3 / 4, 1 / 1 of the water inlet flow rate. The water outlet 10 at the bottom of the device was used for the solution in the anode chamber to flow out of the reaction tank 3, and the water outlet flow rate was consistent with the water inlet flow rate of the cathode side inlet 11. The treatment results are shown in Figure 5 .

[0072] As Figure 5 shown, the extraction flow rate of the in-situ water extraction filter device inside the device had little effect on the hardness removal effect and the pH of the outlet water. However, when the extraction flow rate was 1:1 of the water inlet flow rate, the hardness removal effect was poor, and the outlet water pH was acidic. Similarly, too slow extraction flow rate also did not achieve the best results. According to Figure 5 , the best hardness removal effect and suitable outlet water pH can be obtained when the extraction flow rate is 3 / 4, so the extraction flow rate of the water extraction filter device in the subsequent examples is selected as 3 / 4.

[0073] Example 3

[0074] Anhydrous calcium chloride, magnesium sulfate, sodium bicarbonate, anhydrous sodium sulfate were used to prepare simulated feed water containing calcium hardness (as CaCO3) 300 mg / L, magnesium hardness 100 mg / L, total alkalinity 300 mg / L, Ca 2+ HCO3 - The simulated feed water had a molar ratio of 1:2 and a conductivity of 3.5 mS / cm. The electrochemical electrolysis unit used a conical asymmetric porous stainless steel cathode (cathode back electrolysis) with a pore size of 1 mm, a graphite particle anode, and the particle anode was packed inside the cathode. The water inlet flow rate was 100 mL / min, and the current density was 10 mA / cm 2 , 5 mA / cm 2 , 10 mA / cm 2 , 15 mA / cm 2 , 20 mA / cm 2Under certain conditions, cathode crystallization water is drawn from an in-situ porous titanium filter (0.22μm pore size) inside the device at a certain flow rate and transported to the anode chamber for further removal of hardness and alkalinity. The extraction speed of the titanium filter is 3 / 4 of the inlet water flow rate. The outlet 10 at the bottom of the device is used for the solution in the anode chamber to flow out of the reaction tank 3. The outlet water flow rate is consistent with the inlet water flow rate on the cathode side. The treatment results are as follows: Figure 6 As shown.

[0075] like Figure 6 As shown, the hardness removal efficiency increases with increasing current density and eventually stabilizes, while the pH of the effluent decreases with increasing current density. Considering energy consumption, effluent pH, and hardness removal effect, 10 mA / cm² was ultimately selected. 2 This current density.

[0076] Example 4

[0077] A solution containing 300 mg / L calcium hardness (calculated as CaCO3), 100 mg / L magnesium hardness, 300 mg / L total alkalinity, and CaCO3 was prepared using anhydrous calcium chloride, magnesium sulfate, sodium bicarbonate, and anhydrous sodium sulfate. 2+ With HCO3 - The simulated feed solution had a molar ratio of 1:2 and a conductivity of 3.5 mS / cm. The electrochemical electrolysis unit employed a conical asymmetric porous stainless steel cathode with a pore size of 1 mm (electrolysis on the back of the cathode) and graphite particle anodes, with the particle anodes packed inside the cathode. The influent flow rate was 100 mL / min, and the current density was 3 mA / cm². 2 5mA / cm 2 10mA / cm 2 15mA / cm 2 20mA / cm 2 The experiment was conducted under the following conditions. Cathode crystallization water was drawn from an in-situ porous titanium filter (0.22 μm pore size) inside the device at a certain flow rate and transported to the anode chamber for further removal of hardness and alkalinity. The extraction speed of the titanium filter was 3 / 4 of the inlet flow rate. The outlet at the bottom of the device was used for the solution in the anode chamber to flow out of reaction tank 3. The outlet flow rate was consistent with the inlet flow rate on the cathode side. The energy consumption results are as follows: Figure 7 As shown.

[0078] like Figure 7 As shown, energy consumption increases with increasing current density. In the experiment, a current density of 10 mA / cm² was selected. 2 At a current density of approximately 1.3 kWh / kg CaCO3, the energy consumption is significantly lower than that of other membrane systems and non-membrane systems. Furthermore, even at higher current densities, the energy consumption of this system is only around 2.35 kWh / kg CaCO3.

[0079] The various embodiments in the specification are described in a related manner, and the same and similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. The above only describes the preferred embodiments of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application is included in the protection scope of the present application.

Claims

1. An electrochemical electrode system, comprising a cathode (1) and an anode (2); characterized in that, The cathode (1) is cone-shaped with several through holes on its wall; the anode (2) is composed of conductive particle filler filled in the cone-shaped cathode (1); the side of the cathode (1) that is in contact with the particle filler of the anode (2) is insulated from the anode (2).

2. The electrochemical electrode system according to claim 1, characterized in that, The cathode (1) is made of titanium, carbon steel or stainless steel.

3. The electrochemical electrode system according to claim 1, characterized in that, The holes on the cathode (1) wall are formed by punching, laser drilling or wire weaving.

4. The electrochemical electrode system according to claim 1, characterized in that, The conductive particle filler is one or a combination of diamond particles, Ti4O7 particles, carbon-based particles and titanium particles.

5. The electrochemical electrode system according to claim 1, characterized in that, The method for insulation treatment is as follows: Insulation is performed on the inner surface of the cathode (1) by spraying an insulating material. The inner surface of the cathode (1) is coated or impregnated with insulating varnish. or The method involves adding a layer of insulating material mesh between the cathode (1) and the anode (2).

6. The use of the electrochemical electrode system according to any one of claims 1-5 in an electrochemical system for removing water hardness or in a method for removing water hardness.

7. An electrochemical system for removing water hardness, characterized in that, The electrochemical electrode system according to any one of claims 1-5 further includes a reaction tank (3); the bottom of the anode (2) of the electrochemical electrode system is provided with an outlet (10) connected to the outside of the reaction tank (3).

8. The electrochemical system for removing water hardness according to claim 7, characterized in that, The reaction tank (3) is also equipped with a water pumping and filtration device for pumping water from the cathode chamber to the anode chamber during the electrolysis process. The inlet end of the water pumping and filtration device is equipped with a filter device (7) for intercepting precipitated particles formed in the cathode chamber.

9. The application of the electrochemical system according to claim 7 or 8 in the removal of water hardness.

10. A method for removing water hardness, characterized in that, Use the electrochemical system as described in claim 7 or 8.

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