A method for treating circulating cooling water

Abstract

The present invention discloses a method for treating circulating cooling water, which includes preparing a coated titanium anode and electrochemically treating the circulating cooling water by using the coated titanium anode and a cathode titanium sheet; first depositing a nickel-polytetrafluoroethylene composite layer on a titanium sheet substrate by magnetron sputtering, and then depositing a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer to obtain the coated titanium anode. The novel coated titanium anode prepared by the present invention has obvious advantages in terms of power consumption and service life. The removal rates of fluoride ions and calcium ions are both higher than those of traditional titanium anodes, and the cell voltage is lower than that of traditional electrodes. The preparation process provided by the present invention does not require the use of precious metals or metal oxides, reduces energy consumption, and thus greatly reduces the production cost and energy consumption of enterprises.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a method for treating circulating cooling water. Background Art

[0002] Circulating cooling water systems play a crucial role in modern industrial production. Their main function is to absorb the heat generated during equipment operation through circulating cooling water, reduce the equipment temperature, and thus ensure the normal operation of the equipment and production efficiency. However, during long-term use, the water quality of circulating cooling water will gradually deteriorate. Especially the presence of fluoride ions (F - ) may have a significant negative impact on the system.

[0003] The sources of fluoride ions in circulating cooling water mainly include fluorine-containing chemicals used in industrial production processes, evaporation concentration in cooling towers, and natural fluoride content in groundwater or surface water. Although fluoride ions have a certain effect on the stability of water quality at a certain concentration, too high a fluoride ion concentration will cause a series of problems, seriously affecting the operation efficiency of the circulating cooling water system and the service life of equipment.

[0004] There are many technical problems in the treatment of circulating cooling water in the prior art. Corrosion problem: Fluoride ions have strong corrosiveness and can react chemically with the metal surface to form soluble fluorides, thereby accelerating the corrosion of metal equipment and pipelines. Especially for metal materials such as aluminum, magnesium, and their alloys, the corrosive effect of fluoride ions is particularly significant. Although traditional anti-corrosion measures can alleviate the corrosion problem to a certain extent, these methods have problems such as high cost, complex maintenance, and possible secondary pollution to the environment. In addition, fluoride ions in water will react with calcium, magnesium and other ions to form insoluble precipitates such as calcium fluoride (CaF2) and magnesium fluoride (MgF2). These precipitates will adhere to the surfaces of pipelines and heat exchangers, forming a scale layer, reducing the heat conduction efficiency, and increasing energy consumption. Traditional descaling methods, such as physical cleaning and chemical cleaning, although they can remove part of the scale layer, are complex in operation, high in cost, and cause great damage to equipment. In addition, the waste liquid generated by chemical cleaning may also pollute the environment. The fluoride ion concentration in circulating cooling water will change dynamically with the operation of the system. Especially during the evaporation concentration process, the fluoride ion concentration will increase significantly. This makes water quality control more complex and difficult.

[0005] Controlling fluoride ion concentration or inhibiting scaling by adding chemical agents produces large amounts of chemical-containing wastewater, causing secondary environmental pollution. Furthermore, the chemicals are expensive to use and require regular replacement. While ion exchange can effectively remove fluoride ions, the regeneration of ion exchange resins requires large amounts of acid and alkali, making the process complex and costly, and the regeneration wastewater is environmentally polluting. Membrane separation technologies, such as reverse osmosis and nanofiltration, can effectively remove fluoride ions, but they require large equipment investments, high operating costs, and stringent requirements for influent water quality. Membrane fouling and clogging are also common. Electrochemical treatment offers advantages in removing fluoride ions and inhibiting scaling, but currently used electrode materials suffer from instability and low electrocatalytic activity. Their performance degrades rapidly, especially at high fluoride ion concentrations. Electrochemical treatment processes consume significant amounts of electricity and have high operating costs, limiting their application in large-scale circulating cooling water treatment. During electrochemical treatment, the oxidation of fluoride ions can produce byproducts, such as fluorine gas (F2), which poses a safety threat to equipment and operators.

[0006] In short, the presence of fluoride ions in the circulating cooling water system has a significant negative impact on the operating efficiency of the system and the service life of the equipment. Although the existing treatment technology can alleviate these problems to a certain extent, it still has many shortcomings in terms of cost, energy consumption, environmental protection and treatment effect. The existing coating electrode has a small oxygen-fluorine potential difference, poor fluoride removal and sterilization efficiency, a short service life of the electrode, and high coating cost and power consumption. There are side reactions on the electrode surface, and the accompanying oxygen evolution reaction is inevitable; the active components in the coating are often precious metal oxides, which are costly. Therefore, the development of more efficient, economical and environmentally friendly new treatment technologies, especially for the removal and control of fluoride ions, has become a key issue that needs to be urgently addressed in the field of circulating cooling water treatment. Summary of the Invention

[0007] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0008] As one aspect of the present invention, the present invention provides a method for treating circulating cooling water, which comprises preparing a coated titanium anode, and using the coated titanium anode and a cathode titanium sheet to electrochemically treat the circulating cooling water to remove fluoride ions;

[0009] The method for preparing the plated titanium anode comprises the following steps:

[0010] Step 1: Fix the titanium substrate on the magnetron sputtering substrate disk, and fix the metal copper target, metal nickel target and polytetrafluoroethylene target in the same vacuum chamber respectively, and control the vacuum degree not to exceed 1×10 -5 Pa;

[0011] Step 2: Introduce argon gas into the magnetron sputtering cavity at a rate of 30 - 80 mL / min, and heat the magnetron sputtering substrate to 250 - 350 °C;

[0012] Step 3: First deposit a nickel-polytetrafluoroethylene composite layer on the titanium substrate by magnetron sputtering, and then deposit a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer to obtain the coated titanium anode.

[0013] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 1, the density of the polytetrafluoroethylene target is 2000 - 2200 kg / m 3 。

[0014] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 2, introduce argon gas into the magnetron sputtering cavity at a rate of 50 - 70 mL / min, and heat the magnetron sputtering substrate to 280 - 300 °C.

[0015] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 3, the thickness of the nickel-polytetrafluoroethylene composite layer is 80 - 100 nm.

[0016] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 3, in the nickel-polytetrafluoroethylene composite layer, the mass ratio of nickel to polytetrafluoroethylene is 1:1 - 1.2.

[0017] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 3, the step of first depositing a nickel-polytetrafluoroethylene composite layer on the titanium substrate by magnetron sputtering includes controlling the metal nickel target by a DC power supply and the polytetrafluoroethylene target by an RF power supply, simultaneously turning on the DC power supply and the RF power supply, and setting the powers of both the DC power supply and the RF power supply to 30 - 40 W, thereby depositing a nickel-polytetrafluoroethylene composite layer on the titanium substrate.

[0018] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 3, the thickness of the nickel-copper composite layer is 180 - 360 nm.

[0019] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: In step 3, the thickness of the nickel-copper composite layer is 270 - 300 nm, and in the nickel-copper composite layer, the mass ratio of nickel to copper is 1:1 - 1.2.

[0020] As a preferred embodiment of the method for treating circulating cooling water according to the present invention: in step 3, plating a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer includes controlling a metal nickel target by a DC power supply and a metal copper target by an RF power supply, simultaneously turning on the DC power supply and the RF power supply, and setting the powers of both the DC power supply and the RF power supply to 30-40 W, so as to plate a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer.

[0021] Advantages of the present invention: The coated titanium anode prepared by the present invention shows significant advantages in multiple aspects. Compared with traditional electrodes, its fluorine evolution potential is significantly reduced, the oxygen-fluorine potential difference is significantly increased, and at the same time, the strengthening life is greatly improved. This indicates that the novel coated titanium anode prepared by the present invention has obvious advantages in power consumption and service life. In addition, through the circulating water treatment test, it is found that the removal rates of fluoride ions and calcium ions of this coated titanium anode are both higher than those of traditional titanium anodes, and the cell voltage is lower than that of traditional electrodes. This further proves that it is superior to traditional titanium anodes in aspects such as defluorination, sterilization, scale inhibition, and power consumption reduction. More importantly, the preparation process provided by the present invention does not require the use of precious metals or metal oxides, reduces energy consumption, and thus greatly reduces the production cost and energy consumption of enterprises. Specific embodiments

[0022] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with specific examples.

[0023] Example 1:

[0024] Step 1: Fix the titanium sheet on the magnetron sputtering base plate, and place a metal Cu target, a metal Ni target, and a PTFE target (the density of the PTFE target is 2200 kg / m 3 ) on the A, B, and C target guns in the same vacuum chamber respectively and fix them, and perform vacuum treatment, controlling the vacuum degree not to exceed 1×10 -5 Pa.

[0025] Step 2: Introduce argon into the magnetron sputtering cavity at a speed of 50 mL / min, maintain the atmosphere pressure at 0.5-2.0 Pa, and set the magnetron sputtering substrate temperature to 300 °C.

[0026] Step 3: Turn on the DC power supply and the RF power supply simultaneously, and set the power of both the DC power supply and the RF power supply to 35 W. Control the metal Ni target with the DC power supply and the PTFE target with the RF power supply to sputter a Ni-PTFE composite layer on the titanium sheet. The thickness of the Ni-PTFE composite layer is about 90 nm, and the mass ratio of Ni to PTFE is 1:1. Then, turn on the DC power supply and the RF power supply simultaneously, set the power of both the DC power supply and the RF power supply to 35 W, control the metal Ni target with the DC power supply and the metal Cu target with the RF power supply to sputter a Ni-Cu composite layer on the Ni-PTFE composite layer. The thickness of the Ni-Cu composite layer is about 180 nm, and the loading is about 75 mg / cm 2 , and the mass ratio of metal Ni to Cu is 1:1 to obtain the coated titanium anode.

[0027] Example 2:

[0028] Step 1: Fix the titanium sheet on the magnetron sputtering base plate, and place the metal Cu target, the metal Ni target, and the PTFE target (the density of the PTFE target is 2200 kg / m 3 ) on the A, B, and C target guns in the same vacuum chamber respectively and fix them, and then perform vacuum pumping, and control the vacuum degree not to exceed 1×10 -5 Pa.

[0029] Step 2: Introduce argon gas into the magnetron sputtering cavity at a speed of 50 mL / min, keep the atmosphere pressure at 0.5 - 2.0 Pa, and set the magnetron sputtering substrate temperature to 300 °C.

[0030] Step 3: Turn on the DC power supply and the RF power supply simultaneously, and set the power of both the DC power supply and the RF power supply to 35 W. Control the metal Ni target with the DC power supply and the PTFE target with the RF power supply to sputter a Ni-PTFE composite layer on the titanium sheet. The thickness of the Ni-PTFE composite layer is about 90 nm, and the mass ratio of Ni to PTFE is 1:1. Then, turn on the DC power supply and the RF power supply simultaneously, set the power of both the DC power supply and the RF power supply to 35 W, control the metal Ni target with the DC power supply and the metal Cu target with the RF power supply to sputter a Ni-Cu composite layer on the Ni-PTFE composite layer. The thickness of the Ni-Cu composite layer is about 270 nm, and the mass ratio of metal Ni to Cu is 1:1 to obtain the coated titanium anode.

[0031] Example 3:

[0032] Step 1: Fix the titanium sheet on the magnetron sputtering base plate, and place the metal Cu target, the metal Ni target, and the PTFE target (the density of the PTFE target is 2200 kg / m 3)(They) are respectively placed on the A, B, and C target guns in the same vacuum chamber and fixed, and then vacuum treatment is carried out, and the vacuum degree is controlled not to exceed 1×10 -5 Pa.

[0033] Step 2: Argon gas is introduced into the magnetron sputtering cavity at a speed of 50 mL / min, the atmosphere pressure is maintained at 0.5 - 2.0 Pa, and the magnetron sputtering substrate temperature is set at 300 °C.

[0034] Step 3: The DC power supply and the RF power supply are turned on simultaneously, and the powers of both the DC power supply and the RF power supply are set to 35 W. The metal Ni target is controlled by the DC power supply, and the PTFE target is controlled by the RF power supply to sputter a Ni-PTFE composite layer on the titanium sheet. The thickness of the Ni-PTFE composite layer is about 90 nm, and the mass ratio of Ni to PTFE is 1:1; then the DC power supply and the RF power supply are turned on simultaneously, the powers of both the DC power supply and the RF power supply are set to 35 W, the metal Ni target is controlled by the DC power supply, and the metal Cu target is controlled by the RF power supply to sputter a Ni-Cu composite layer on the Ni-PTFE composite layer. The thickness of the Ni-Cu composite layer is about 360 nm, and the mass ratio of metal Ni and Cu is 1:1, obtaining the coated titanium anode.

[0035] Comparative Example 1:

[0036] Step 1: The titanium sheet is fixed on the magnetron sputtering base plate, and the metal Cu target, the metal Ni target, and the PTFE target (the density of the PTFE target is 2200 kg / m 3 )(They) are respectively placed on the A, B, and C target guns in the same vacuum chamber and fixed, and then vacuum treatment is carried out, and the vacuum degree is controlled not to exceed 1×10 -5 Pa.

[0037] Step 2: Argon gas is introduced into the magnetron sputtering cavity at a speed of 50 mL / min, the atmosphere pressure is maintained at 0.5 - 2.0 Pa, and the magnetron sputtering substrate temperature is set at 300 °C.

[0038] Step 3: The DC power supply and the RF power supply are turned on simultaneously, and the powers of both the DC power supply and the RF power supply are set to 35 W. The metal Ni target is controlled by the DC power supply, and the PTFE target is controlled by the RF power supply to sputter a Ni-PTFE composite layer on the titanium sheet. The thickness of the Ni-PTFE composite layer is about 90 nm, and the mass ratio of Ni to PTFE is 1:1; then the RF power supply is turned on, the power of the RF power supply is set to 70 W, and the metal Cu target is controlled by the RF power supply to sputter a layer of metal Cu on the Ni-PTFE composite layer. The thickness of the metal Cu layer is about 180 nm, obtaining the coated titanium anode.

[0039] To evaluate the electrochemical treatment performance of the coated titanium anodes prepared in Examples 1, 2, 3 and Comparative Example 1 of the present invention, the following test experiments were carried out:

[0040] Oxygen evolution / fluorine evolution potential test: Four coated anode samples with dimensions of 1 cm × 1 cm were taken. The first one was placed together with a titanium sheet cathode and a saturated calomel electrode in a 0.5 mol / L KOH electrolyte solution, and the second one was placed in a saturated NaCl electrolyte solution. The oxygen evolution potential and fluorine evolution potential were measured by an electrochemical workstation, and the oxygen-fluorine potential difference was calculated. The experimental conditions were: the electrolyte temperature was 25°C, and the anode current density was 0.02 A / cm 2 .

[0041] Enhanced life test: The third sample was placed together with a titanium sheet cathode in a 1 mol / L KOH electrolyte solution, and a constant current density of 2 A / cm was applied through a DC power supply 2 , the electrolyte temperature was 40°C, and the enhanced life test was carried out. When the cell voltage increased by 5 V compared with the initial value, the electrode was determined to fail.

[0042] Fluorine evolution efficiency test: The fourth sample and the titanium sheet cathode were placed in a 3 g / L NaF electrolyte solution. The electrolyte temperature was 25°C. After electrolyzing at a constant current density of 0.15 A / cm 2 for 1 hour, the effective fluorine content in the electrolyte was measured by chemical analysis, and the fluorine evolution efficiency was calculated.

[0043] Table 1 Test results of the electrochemical performance of the coated titanium anode

[0044]

[0045] As can be seen from Table 1, the coated titanium anode prepared by the method of the present invention has a large oxygen-fluorine potential difference, an enhanced life of more than 220 h, and a high fluorine evolution efficiency, which is significantly better than the traditional Ti / RuO2 + IrO2 + TiO2 coated titanium anode.

[0046] To evaluate the performance of the coated titanium anode prepared by the present invention in circulating water treatment, the samples of Example 1, Example 2, Example 3 and Comparative Example 1 were tested. The specific test scheme was as follows: The above-mentioned titanium anode samples and a pure titanium cathode sheet with a matching area were jointly immersed in a simulated circulating cooling aqueous solution system (aqueous solution prepared with calcium fluoride). Electrolysis was applied through a DC power supply. The electrolyte temperature was controlled to be constant at 25°C, the anode current density was set to 0.03 A / cm², a 60 L standard electrolytic cell was used, and the effective area of the electrode was maintained at 50 cm². After continuous electrolysis for 2 hours, key parameters such as the cell voltage, fluoride ion (F⁻) concentration and calcium ion (Ca²⁺) concentration of the electrolysis system were measured respectively. The experimental results are shown in Table 2.

[0047] Table 2 Test results of the performance of the coated titanium anode in electrolyzing circulating water

[0048]

[0049] With the mechanism of atomic layer-by-layer deposition, magnetron sputtering technology can prepare homogeneous electrodes with a highly uniform composition distribution and precisely controllable film thickness. This process effectively avoids the inherent defects existing in the preparation of traditional electrodes, such as randomly distributed active sites, insufficient local density, and easy detachment under the electrolytic environment. In terms of modifying the electrode material, the magnetron co-sputtering process can achieve uniform doping of Cu and Ni dual active components at the atomic scale. By constructing a high-density heterointerfacial structure, the number of active sites is significantly increased, and the synergy is improved. This doping effect not only optimizes the electron transfer characteristics on the electrode surface, but also enhances the electrochemical potential energy of the electro-oxidation reaction through the synergistic catalysis, substantially improving the redox potential difference of the electrode in the oxygen-fluorine system. At the same time, an anti-corrosion conductive layer (Ni-PTFE composite layer) is added between the substrate and the active layer, forming a fast electron transport channel while avoiding solution corrosion. PTFE acts as a support to extend the anti-corrosion life of the electrode, and Ni acts as a conductive substance to maintain the current. At the same time, a Ni-Cu-Ni bridge is constructed with the upper Ni-Cu composite layer to accelerate the reaction and improve the fluorine evolution efficiency and the removal rates of fluoride ions and calcium ions. The present invention does not require the use of precious metals or metal oxides, reducing energy consumption, thereby greatly reducing the production cost and energy consumption of enterprises.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for treating circulating cooling water, characterized in that: It includes preparing a coated titanium anode and electrochemically treating the circulating cooling water with the coated titanium anode and a cathode titanium sheet to remove fluoride ions; The preparation method of the coated titanium anode includes the following steps. Step 1: Fix the titanium substrate on the magnetron sputtering base plate, and fix the metal copper target, metal nickel target and polytetrafluoroethylene target in the same vacuum chamber respectively, and control the vacuum degree not to exceed 1×10 -5 Pa; Step 2: Introduce argon into the magnetron sputtering cavity at a speed of 30 - 80 mL / min, and heat the magnetron sputtering substrate to 250 - 350 °C; Step 3: Deposit a nickel-polytetrafluoroethylene composite layer on the titanium sheet substrate by magnetron sputtering first, and then deposit a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer to obtain the coated titanium anode; In Step 3, depositing a nickel-polytetrafluoroethylene composite layer on the titanium sheet substrate by magnetron sputtering first includes controlling the metal nickel target by a DC power supply and the polytetrafluoroethylene target by an RF power supply, simultaneously turning on the DC power supply and the RF power supply, and setting the powers of both the DC power supply and the RF power supply to 30 - 40 W, so as to deposit a nickel-polytetrafluoroethylene composite layer on the titanium sheet substrate; Depositing a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer includes controlling the metal nickel target by a DC power supply and the metal copper target by an RF power supply, simultaneously turning on the DC power supply and the RF power supply, and setting the powers of both the DC power supply and the RF power supply to 30 - 40 W, so as to deposit a nickel-copper composite layer on the nickel-polytetrafluoroethylene composite layer.

2. The treatment method of the circulating cooling water according to claim 1, wherein: In Step 1, the density of the polytetrafluoroethylene target is 2000~2200 kg / m 3 .

3. The treatment method of the circulating cooling water according to claim 1 or 2, characterized in that: In Step 2, introduce argon into the magnetron sputtering cavity at a speed of 50 - 70 mL / min, and heat the magnetron sputtering substrate to 280 - 300 °C.

4. The treatment method of circulating cooling water according to claim 1 or 2, characterized in that: In Step 3, the thickness of the nickel-polytetrafluoroethylene composite layer is 80 - 100 nm.

5. The treatment method of circulating cooling water according to claim 1 or 2, characterized in that: In the nickel-polytetrafluoroethylene composite layer in Step 3, the mass ratio of nickel to polytetrafluoroethylene is 1:1 - 1.

2.

6. The treatment method of the circulating cooling water according to claim 1 or 2, characterized in that: In Step 3, the thickness of the nickel-copper composite layer is 180 - 360 nm.

7. The treatment method of circulating cooling water according to claim 1 or 2, characterized in that: In Step 3, the thickness of the nickel-copper composite layer is 270 - 300 nm, and in the nickel-copper composite layer, the mass ratio of nickel to copper is 1:1 - 1.2.

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