Preparation and application of iron-doped titanium suboxide electrode

Abstract

The application discloses a preparation and application of an iron-doped titanium suboxide electrode. The iron-doped titanium suboxide electrode is prepared by mechanically treating an iron compound and titanium suboxide, is used as an anode, and is used for synthesizing a disinfectant with natural seawater as an electrolyte and being coupled with photovoltaic technology, so that a solar energy driven electrolysis device is successfully constructed, the disinfectant with active components of hypochlorous acid is synthesized, and pathogenic bacteria in ballast water are killed. The electrode is composed of non-noble metal elements, and the price is much lower than that of a commercial size stable anode composed of noble metals ruthenium and iridium, and the electrode shows a reaction activity which is significantly higher than that of the commercial size stable anode, and the problem that high-abundance chlorine ions in seawater are difficult to be selectively oxidized to hypochlorous acid is solved. The electrode is stable in chemical properties, friendly to the environment, and cannot cause secondary pollution, and can be driven by solar energy to electrochemically synthesize a disinfectant without depending on power resources in ocean navigation, so that disinfection and sterilization of ship ballast water are realized, and the electrode is very worth promoting.

Description

Technical Field

[0001] This invention relates to a method for preparing an iron-doped titanium suboxide electrode, and also to an application method for synthesizing a disinfectant by electrolyzing the iron-doped titanium suboxide electrode in seawater. Background Technology

[0002] Ballast water is an essential component for ensuring the safe and stable operation of ships during ocean voyages. During ocean-going operations, the ballast water carried by these vessels contains a large number of microorganisms and viruses originating from the surrounding waters, which may lead to serious biological invasions in the waters along the route or at the destination, endangering marine ecosystems and human health.

[0003] Current ship ballast water management systems mainly consist of three units: pumping, filtration, and disinfection. The filtration unit can remove relatively large organisms, but it is ineffective against smaller bacteria and viruses. The disinfection unit can use ultraviolet (UV) irradiation equipment, which can remove most small harmful bacteria and viruses; however, due to the inherent properties of UV light, its application is limited and energy consumption is high. Therefore, the disinfection unit can also utilize active chlorine disinfectant, which has advantages such as strong oxidizing properties, low cost, and strong bactericidal ability, making it a feasible reagent for ballast water treatment.

[0004] In reality, the active chlorine disinfectant currently used in disinfection units is actually a hypochlorous acid solution. However, if it is used as a disinfection technology, the hypochlorous acid solution needs to be stored in advance. Its large volume, easy decomposition, and difficulty in carrying make it unsuitable for use in ocean voyages.

[0005] In existing ocean-going navigation technologies, the disinfection technique employed is the in-situ preparation of active chlorine solutions, which is more practically feasible compared to the disposable storage of hypochlorous acid solutions. This in-situ preparation of hypochlorous acid disinfectant relies on an electrochemical chlorine evolution reaction. Chlorine gas is produced by electrolyzing a solution containing chloride ions, and the chlorine gas is further hydrolyzed to obtain a hypochlorous acid solution, which is then used as the disinfectant. During ocean voyages, seawater, containing a large amount of chloride ions, is a naturally suitable electrolyte raw material for disinfectant production.

[0006] The core of electrochemical chlorine evolution reaction technology is the chlorine evolution electrode, which directly determines the working efficiency of the entire disinfection unit. Commonly used chlorine evolution electrodes on the market are size-stabilized anodes based on the precious metals ruthenium and iridium. These size-stabilized anodes exhibit excellent chlorine evolution performance in the chlor-alkali industry; however, due to the limited availability of precious metal resources as raw materials, size-stabilized anodes are often expensive.

[0007] On the other hand, due to the physicochemical principle of potential competition in the electrochemical oxygen evolution reaction, the use of size-stable anodes as chlorine evolution electrodes is also limited. They can only exhibit high selectivity for chlorine evolution reaction under conditions of high NaCl concentration (chloride ion concentration > 1 mol / L) and low pH value (pH value < 3). When used in the chlor-alkali industry, the concentration of raw materials and reaction conditions should be designed in advance.

[0008] Unfortunately, the chloride ion concentration in the vast ocean is far lower than that of the electrolytes used in the chlor-alkali industry. Furthermore, seawater in open water is generally considered to have a neutral pH, making size-stabilized anodes based on the precious metals ruthenium and iridium extremely limited by the competitive oxygen evolution reaction. When using seawater directly as a feedstock, these size-stabilized anodes typically exhibit low selectivity for the chloride evolution reaction.

[0009] Therefore, existing precious metal size-stabilized anodes are difficult to apply to ballast water disinfection systems for ocean-going vessels. Developing efficient, stable, and inexpensive chlorine-electrode processes in seawater remains a popular research topic for those skilled in the art. Summary of the Invention

[0010] To address the challenge of ballast water disinfection in ocean-going vessels, the primary technical problem this invention aims to solve is to provide a method for preparing an iron-doped titanium suboxide electrode.

[0011] Another technical problem to be solved by the present invention is to provide an iron-doped titanium suboxide electrode.

[0012] Another technical problem to be solved by the present invention is to provide a method for synthesizing disinfectant by electrolyzing seawater using an iron-doped titanium suboxide electrode.

[0013] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0014] According to a first aspect of the present invention, a method for preparing an iron-doped titanium suboxide electrode is provided, comprising the following steps:

[0015] Step 1: Take 1 part by weight of titanium suboxide powder, add 0.1-5 parts by weight of ferrous sulfate heptahydrate and put it into a ball mill jar. Add quartz beads into the ball mill jar, seal it, and ball mill for more than 2 hours.

[0016] Step 2: After ball milling is completed, take out the powder, wash it with water more than five times to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0017] Step 3: Prepare an isopropanol solution containing 3% Nafion reagent by mixing Nafion (perfluorosulfonic acid polymer) reagent with isopropanol as a powder dispersant;

[0018] Step 4: Take 0.01g of the iron-doped titanium suboxide powder prepared in Step 2, add it to 1mL of dispersant, use an ultrasonic instrument or a vibrator to disperse the powder evenly in the dispersant, spray (or drop-coat, apply) the evenly dispersed mixed solution onto a 2cm×2cm carbon paper carrier, and air dry it naturally to obtain the iron-doped titanium suboxide electrode.

[0019] Preferably, in step 1, 0.5-5 parts by weight of ferrous sulfate heptahydrate can be replaced with 0.36-3.6 parts by weight of ferric sulfate; or 0.29-4.25 parts by weight of ferric chloride; or 0.23-2.275 parts by weight of ferrous chloride.

[0020] Preferably, step 1: take 1 part by weight of titanium suboxide powder, add 0.015-1 part by weight of iron oxide and put it into a ball mill jar, add quartz beads into the ball mill jar, seal it, and ball mill for more than 2 hours;

[0021] Step 2: After ball milling is completed, take out the powder, wash away excess unreacted iron oxide with sufficient dilute hydrochloric acid, and then wash with water to remove unreacted ions to obtain iron-doped titanium suboxide powder.

[0022] Step 3: Prepare an isopropanol solution containing 3% Nafion reagent as a powder dispersant by mixing Nafion reagent with isopropanol.

[0023] Step 4: Take 0.01g of the iron-doped titanium suboxide powder prepared in Step 2, add it to 1mL of dispersant, use an ultrasonic instrument or a vibrator to disperse the powder evenly in the dispersant, spray (or drop-coat, apply) the evenly dispersed mixed solution onto a 2cm×2cm carbon paper carrier, and air dry it naturally to obtain the iron-doped titanium suboxide electrode.

[0024] Preferably, the titanium suboxide powder is pure titanium heptaoxide, or titanium heptaoxide powder containing no more than 10% by mass of titanium pentoxide.

[0025] Preferably, the ball milling and mechanical stirring time is 2 to 24 hours.

[0026] According to a second aspect of the present invention, an iron-doped titanium suboxide electrode is provided, which is prepared by the above-described preparation method.

[0027] According to a third aspect of the present invention, a method for applying an iron-doped titanium suboxide electrode is provided, comprising the following steps:

[0028] Using the prepared iron-doped titanium suboxide electrode as the anode, a platinum electrode as the cathode, and a saturated calomel electrode as the reference electrode, ordinary seawater was electrolyzed to produce a chlorine evolution reaction, thereby preparing active chlorine gas.

[0029] Preferably, the electrolysis device used in the application method includes an external power supply; its anode is an anode prepared by iron-doped titanium suboxide powder on a carbon paper carrier, and nickel foam is used as the cathode; the sealing gasket in the reaction vessel is between the anode and the cathode, and seawater (or ballast water) flows into the reaction vessel from the cathode side through a peristaltic pump, stays briefly in the reactor, and then flows back into the seawater (or ballast water) through the anode side.

[0030] Preferably, 300 mL of ballast water is used, and after passing through an electrolysis device at a rate of 30 mL / min, the concentration of active chlorine (calculated as chlorine gas) in the ballast water reaches more than 100 mg / L after 5 minutes of reaction.

[0031] Preferably, at midday on a clear, cloudless day with direct sunlight, an 8.5cm × 5.6cm solar panel is used as the power source, with voltage / current parameters of 5V / 160mA. 300mL of seawater is drawn using a peristaltic pump at a rate of 30mL / min, passed through an electrolysis device, and reacted for 5 minutes. The bacterial Log (sterilization rate) in the electrolyte is then measured to be 7.

[0032] The technical principle of this invention is as follows:

[0033] Seawater contains a large amount of Cl - Cl - Cl2 can be formed by losing electrons at a suitable electrochemical anode, and therefore can be generated by electrolyzing seawater. Cl2 can be further hydrolyzed to form HOCl and OCl. - All three have strong disinfection and sterilization activities and are suitable for ballast water treatment.

[0034] However, due to intense competition in the electrochemical oxygen evolution reaction, the commercially available precious metal size-stabilized anodes often exhibit low selectivity for chlorine evolution (approximately 50%) during seawater electrolysis, resulting in a significant waste of electrical energy. Consequently, they are largely unsuitable for use in the electrolysis of seawater to prepare disinfectant solutions.

[0035] The iron-doped titanium suboxide electrode provided by this invention exhibits extremely high stability and a high oxygen evolution reaction potential, while its raw materials are inexpensive. Based on this iron-doped titanium suboxide electrode, the seawater chlorination system prepared by this invention can efficiently synthesize hypochlorous acid from seawater through electrolysis, achieving a chlorination reaction selectivity of up to 75%, significantly superior to existing commercially available precious metal size-stabilized anodes. Furthermore, the cost of this iron-doped titanium suboxide electrode is extremely low, approximately several hundred yuan per square meter, far lower than the cost of commercial precious metal size-stabilized anodes (tens of thousands of yuan per square meter), indicating broad prospects for commercial application.

[0036] Using this iron-doped titanium suboxide electrode and powered by a solar panel, an electrochemical reaction system was designed that can efficiently meet the requirements for ballast water disinfection and sterilization, and has very good application prospects.

[0037] The method for preparing iron-doped titanium suboxide electrodes according to the present invention is a mechanochemical preparation method, which is very easy to scale up production and supply on a large scale.

[0038] The iron-doped titanium suboxide electrode is composed entirely of inexpensive metals, resulting in low raw material costs. Furthermore, its chlorine evolution reaction activity and selectivity are significantly stronger than those of size-stable anodes. Based on this iron-doped titanium suboxide electrode, a novel method for solar-driven electrochemical chlorine evolution and disinfection solution synthesis was designed. This method allows for the on-site, large-scale preparation of hypochlorous acid solution without relying on the ship's power resources. This solution can be used to inactivate harmful bacteria and viruses and disinfect ballast water. The method exhibits stable performance and excellent results, making it suitable for practical ballast water management and preventing potential biological invasion.

[0039] Hypochlorous acid disinfectant is made from natural seawater, and ballast water used during ocean voyages can be directly utilized as part of the system. When modifying existing ballast water disinfection units used during ocean voyages, virtually no additional consumable raw materials are required. It is solar-powered, eliminating the need for onboard electricity. Attached Figure Description

[0040] Figure 1 The X-ray diffraction pattern of the iron-doped titanium suboxide electrode prepared in Example 1;

[0041] Figure 2 Here is a high-resolution transmission electron microscope (TEM) image of the iron-doped titanium suboxide electrode prepared in Example 1.

[0042] Figure 3 Comparison of the chlorine evolution curves of the iron-doped titanium suboxide electrode prepared in Example 2 and titanium suboxide in seawater;

[0043] Figure 4 This is a schematic diagram of the solar-powered electrochemical device for in-situ preparation of disinfectant via seawater electrolysis, as shown in Example 3. Detailed Implementation

[0044] The technical content of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] Example 1

[0046] Step 1: Weigh 2g of titanium suboxide powder, add 1g of ferrous sulfate heptahydrate, put it into a ball mill jar, add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm into the ball mill jar, seal it and put it into the ball mill.

[0047] The ball was milled for 4 hours at a speed of 500 revolutions per minute.

[0048] Step 2: After ball milling is completed, remove the powder, wash it five times with water to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0049] like Figure 1 and Figure 2 The X-ray diffraction pattern and high-resolution transmission electron microscopy (HRTEM) elemental distribution pattern of the obtained iron-doped titanium suboxide powder are shown in the figure. As shown, the iron element in the powder is uniformly dispersed in the titanium suboxide. At this point, the powder obtained after ball milling is an amorphous particle of approximately 400 mesh. The iron element replaces some titanium atoms in the titanium suboxide crystal in the form of ferric iron, and the mass percentage of iron in the finished iron-doped titanium suboxide powder is approximately 1%.

[0050] The particle size of the titanium suboxide powder is ≤1.0μm.

[0051] Example 2

[0052] Step 1: Weigh 2g of titanium suboxide powder, add 2.5g of ferrous sulfate heptahydrate, put it into a ball mill jar, add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm into the ball mill jar, seal it and put it into the ball mill.

[0053] The ball was milled for 4 hours at a speed of 500 revolutions per minute.

[0054] Step 2: After ball milling is completed, remove the powder, wash it five times with water to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0055] Step 3: Prepare a 3% Nafion isopropanol solution using commercially available Nafion reagent and isopropanol as a powder dispersant.

[0056] Take 0.01 g of undoped ordinary titanium suboxide powder and 0.01 g of iron-doped titanium suboxide powder, respectively, and add them to 1 mL of dispersant. Use an ultrasonic instrument or a vibrator to disperse the powder evenly in the dispersant. Spray (or drop-coat, coat) the evenly dispersed mixture onto a 2 cm × 2 cm carbon paper carrier, and let it air dry naturally to serve as the anode. The two electrodes prepared by the above method have equal mass and a consistent thickness of approximately 1 mm.

[0057] Using a platinum electrode as the cathode and a saturated calomel electrode as the reference electrode, a chlorine evolution electrolysis apparatus was constructed using ordinary seawater. The chlorine evolution polarization curve was scanned to test the chlorine evolution performance of the electrodes. Figure 3 As shown, the anode prepared with iron-doped titanium suboxide powder exhibits significantly stronger chlorine evolution performance in the electrolysis reaction than the electrode prepared with undoped ordinary titanium suboxide.

[0058] Example 3

[0059] Step 1: Weigh 2g of titanium suboxide powder, add 2.5g of ferrous sulfate heptahydrate, put it into a ball mill jar, add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm into the ball mill jar, seal it and put it into the ball mill.

[0060] The ball was milled for 4 hours at a speed of 500 revolutions per minute.

[0061] Step 2: After ball milling, remove the powder, wash it five times with water to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder. The iron content in the iron-doped titanium suboxide powder prepared in this way is 2% by mass.

[0062] A 3% Nafion isopropanol solution was prepared using commercially available Nafion reagent and isopropanol as a powder dispersant.

[0063] Take 0.01 g of undoped ordinary titanium suboxide powder and 0.01 g of iron-doped titanium suboxide powder, respectively, and add them to 1 mL of dispersant. Use an ultrasonic instrument or a vibrator to disperse the powder evenly in the dispersant. Spray (or drop-coat, coat) the evenly dispersed mixture onto a 2 cm × 2 cm carbon paper carrier, and let it air dry naturally to serve as the anode. The two electrodes prepared by the above method have equal mass and consistent thickness, approximately 1 mm.

[0064] A platinum electrode was used as the cathode, a saturated calomel electrode was used as the reference electrode, and ordinary seawater was used for the electrolysis experiment.

[0065] Size-stable anodes made of the same size of precious metals ruthenium and iridium were prepared, both measuring 2cm × 2cm and 1mm thick. A saturated calomel electrode was used as a reference electrode, and ordinary seawater was used for electrolysis experiments.

[0066] Under the same conditions, a control experiment was conducted on the three types of anodes mentioned above:

[0067] After electrolysis for ten minutes, the active chlorine content (as chlorine gas) generated was tested by iodometric titration, and the active chlorine generation rate and selectivity were calculated. The results are shown in Table 1 below: The chlorine evolution reaction was carried out by three different anodes. The chlorine evolution performance of the iron-doped titanium suboxide electrode was significantly stronger than that of the undoped ordinary titanium suboxide electrode or the size-stable anode.

[0068] Table 1 shows the chlorine evolution reaction performed at three different anodes.

[0069]

[0070] After ten minutes of reaction, the concentration of active chlorine (as chlorine gas) was measured, and the Faradaic efficiency of the three electrodes was calculated. The results are shown in Table 2 below: Faradaic efficiency of three different anodes. It shows that the chlorine evolution performance of the iron-doped titanium suboxide electrode is significantly stronger than that of the undoped ordinary titanium suboxide electrode or the size-stable anode.

[0071] Table 2. Faraday efficiency of three different anodes

[0072] Titanium suboxide Iron-doped titanium suboxide Size-stable anode Faraday efficiency 3％ 75％ 45％

[0073] Example 4

[0074] Sample 1

[0075] Step 1: Weigh 2g of titanium suboxide powder, add 2.5g of ferrous sulfate heptahydrate, and place them in ball mill jar 1. Add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm to ball mill jar 1, seal, and place in a ball mill. Ball mill at 500 rpm for 5 hours.

[0076] Step 2: After ball milling is completed, take out the powder, wash it with water more than five times to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0077] Step 3: The iron-doped titanium suboxide powder prepared has an iron content of 2.01% by mass and is labeled as Sample 1.

[0078] Sample 2

[0079] Step 1: Weigh 2g of titanium suboxide powder, add 0.06g of iron oxide, and place them in ball mill jar 2. Add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm to ball mill jar 2, seal, and then place in a ball mill. Ball mill at 600 rpm for 6 hours.

[0080] Step 2: After ball milling is completed, take out the powder, wash away excess unreacted iron oxide with sufficient dilute hydrochloric acid, then wash with water to remove unreacted ions, and dry to obtain iron-doped titanium suboxide powder.

[0081] Step 3: The iron-doped titanium suboxide powder prepared has an iron content of 2.09% by mass and is labeled as Sample 2.

[0082] Sample 3

[0083] Step 1: Weigh 2g of titanium suboxide powder, add 1.72g of anhydrous ferric sulfate, and place them in ball mill jar 3. Add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm to ball mill jar 3, seal, and place in a ball mill. Ball mill at 500 rpm for 4 hours.

[0084] Step 2: After ball milling is completed, take out the powder, wash it with water more than five times to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0085] Step 3: The iron-doped titanium suboxide powder prepared has an iron content of 2.12% by mass and is labeled as sample 3.

[0086] After preparing the finished products from the above three samples, the following steps were followed:

[0087] Step 4: Prepare an isopropanol solution containing 3% Nafion using commercially available Nafion reagent and isopropanol as a dispersant for the powder.

[0088] Step 5: Weigh 0.01g of each of the three samples and undoped titanium suboxide powder (as a control group), add 1mL of the dispersant prepared in Step 4, and use an ultrasonic or vibrator to disperse the powder evenly in the dispersant. Spray (or drop-coat, coat) the evenly dispersed mixture onto a 2cm×2cm carbon paper carrier, and let it air dry naturally to serve as the anode.

[0089] The four types of electrodes prepared by this method have equal mass and uniform thickness, approximately 1 mm.

[0090] A platinum electrode was used as the cathode, a saturated calomel electrode was used as the reference electrode, and ordinary seawater was used for the electrolysis experiment.

[0091] Under the same conditions, a control experiment was conducted on the four types of anodes mentioned above:

[0092] After electrolysis for 10 minutes, the content of generated active chlorine (expressed as chlorine gas) was tested using iodometric titration. The active chlorine generation rate and selectivity were calculated, and the results are shown in Table 3 below: chlorine evolution reactions were performed on four different anodes. The active chlorine production performance of the three iron-doped titanium suboxide electrodes (samples 1 / 2 / 3) with different iron sources was stronger than that of undoped titanium suboxide (control group). Among them, sample 1, with ferrous sulfate heptahydrate powder, showed better active chlorine production performance.

[0093] Table 3 shows the chlorine evolution reaction performed at four different anodes.

[0094]

[0095] Example 5

[0096] Step 1: Weigh 4g of titanium suboxide powder, add 5g of ferrous sulfate heptahydrate, put them into a ball mill jar, add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm into the ball mill jar, seal it and put it into the ball mill.

[0097] The ball was milled for 4 hours at a speed of 500 revolutions per minute.

[0098] Step 2: After ball milling is completed, remove the powder, wash it five times with water to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder.

[0099] Step 3: Use commercially available Nafion reagent and isopropanol to prepare a 3% Nafion isopropanol solution as a dispersant for the powder.

[0100] Step 4: Disperse 0.05g of the iron-doped titanium suboxide powder prepared in Step 2 evenly in 5mL of dispersant using an ultrasonicator or vibrator. Spray (or drop-coat, coat) the evenly dispersed mixture onto a 4cm×4cm carbon paper carrier. Allow the coated electrode to air dry naturally to serve as the anode.

[0101] The prepared anode needs to be uniformly coated, with its surface completely covered by iron-doped titanium suboxide powder. A 4cm × 4cm nickel foam of the same size is selected as the cathode, with the following composition: Figure 4 An electrolysis apparatus. The electrode prepared by this method has a thickness of 1 mm.

[0102] This invention uses iron-doped titanium suboxide as the anode, sunlight as the energy source, a solar panel as the power source, and natural seawater as the electrolyte to synthesize hypochlorous acid disinfectant, which is then used for disinfection and sterilization of ballast water. This technology can also be coupled with photovoltaic technology to synthesize hypochlorous acid disinfectant without relying on additional power from the ship's electrical resources. It efficiently treats pathogenic bacteria and viruses in ship ballast water, exhibiting stable performance and excellent results.

[0103] like Figure 4 As shown, the electrolysis device used in this embodiment of the invention includes an external power supply and an internal anode made of iron-doped titanium suboxide powder on a carbon paper carrier and a nickel foam cathode. A sealing gasket is placed between the anode and cathode, and a cathode-anode clamping device is also provided. In this electrolysis device, seawater (or ballast water) flows into the reaction vessel from the cathode side via a peristaltic pump, stays briefly in the reactor, and then flows back into the ballast water through the anode side. The residence time of the ballast water can be controlled by adjusting the ballast water flow rate, thereby controlling the concentration of active chlorine in the ballast water.

[0104] In this embodiment, for a total of 300 mL of ballast water (ordinary seawater or simulated seawater), the ballast water is drawn at a rate of 30 mL / min and passed through the electrolysis device. After reacting for 5 minutes, the concentration of active chlorine (calculated as chlorine gas) in the ballast water reaches 100 mg / L, which is far higher than the national ballast water management requirement (10 mg / L active chlorine).

[0105] Iron-doped titanium suboxide powder was prepared by mixing 1g of titanium suboxide powder with 0.5g and 1g of ferrous sulfate heptahydrate, respectively, in the manner described above. The resulting anode was then placed in the electrolysis apparatus. For a total volume of 300mL of ballast water (ordinary seawater or simulated seawater), the ballast water (ordinary seawater or simulated seawater) was drawn at a rate of 30mL / min and passed through the electrolysis apparatus. After reacting for 5 minutes, the concentration of active chlorine (calculated as chlorine gas) in the ballast water reached 13mg / L and 105mg / L, respectively.

[0106] Therefore, it can be seen that the content of the prepared active chlorine (chlorine meter) has exceeded the national standard requirements, which is sufficient to solve the problems in the existing technology, such as the large total volume of ballast water, the inability to directly electrolyze chlorine, and the adverse effects of seawater temperature rise and chloride ion content decrease when directly electrolyzing stagnant seawater.

[0107] On a clear, cloudless day at midday with direct sunlight, using an 8.5cm × 5.6cm solar panel as the power source, the voltage / current parameters of the power supply are: 5V / 160mA. 300mL of solutions containing *Escherichia coli*, *Staphylococcus aureus*, and *Vibrio alginolyticus* (initial concentration: 1.2 × 10⁻⁶) were used. 7 Three types of simulated seawater (CFU / mL) were used as electrolytes. A peristaltic pump drew simulated seawater at a rate of 30 mL / min and passed it through the electrolysis device. After reacting for 5 minutes, the bacterial content in the electrolyte was detected.

[0108] Meanwhile, a control experiment was conducted using 300 mL of 0.5 mol / L sodium sulfate solution containing Escherichia coli, Staphylococcus aureus, and Vibrio alginolyticus. The results are shown in Table 4 below: As can be seen from the solar-driven chlorination sterilization, all bacteria using seawater as electrolyte were inactivated, while the control group showed no bacterial inactivation activity.

[0109] Table 4 Solar-driven chlorine sterilization

[0110]

[0111] Example 6:

[0112] Step 1: Weigh 2g of titanium suboxide powder, add 3g of ferrous chloride, and place them in a ball mill jar. Add 20 quartz beads with a diameter of 5mm and 40 quartz beads with a diameter of 2mm to the ball mill jar, seal it, and place it in a ball mill. Ball mill at 500 rpm for 6 hours.

[0113] Step 2: After ball milling is completed, take out the powder, wash it with water more than five times to remove unreacted ions, and dry it to obtain iron-doped titanium suboxide powder, which is recorded as sample 4.

[0114] In the above steps, keep the amount of 2g titanium suboxide powder unchanged, and add 4.8g ferrous sulfate heptahydrate, 1.78g ferric sulfate, 6.2g ferric sulfate, 1.44g ferric chloride, 2.8g ferric chloride, and 1.13g ferrous chloride respectively.

[0115] In the above steps, keep the amount of 2g of titanium suboxide powder unchanged, and add 0.03g of iron oxide and 2g of iron oxide respectively. The difference is that in step 2, dilute hydrochloric acid is used to wash until unreacted materials are removed.

[0116] Step 3: Prepare a 3% Nafion isopropanol solution using commercially available Nafion reagent and isopropanol as a powder dispersant.

[0117] Step 4: Weigh 0.01g of each of the above samples and add them to 1mL of dispersant. Use an ultrasonic instrument or vibrator to disperse the powder evenly in the dispersant. Spray (or drop-coat, coat) the evenly dispersed mixture onto a 2cm×2cm carbon paper carrier and air dry it naturally to serve as the anode. The various electrodes prepared by the above method have approximately equal mass and uniform thickness, about 1mm.

[0118] A platinum electrode was used as the cathode, a saturated calomel electrode was used as the reference electrode, and ordinary seawater was used for the electrolysis experiment.

[0119] Under the same conditions, a control experiment was conducted on the various anodes mentioned above:

[0120] After electrolysis for ten minutes, the content of active chlorine generated (as chlorine gas) was tested by iodometric titration, and the active chlorine generation rate and selectivity were calculated. The results are shown in Table 5 below: Chlorine evolution reaction was carried out at the anodes of different iron sources.

[0121] Table 5 shows the chlorine evolution reaction performed at anodes with different iron sources.

[0122]

[0123] It should be noted that, in one embodiment of the present invention, the titanium suboxide powder used is pure titanium heptoxide powder. This pure reagent is a custom-made product and is relatively expensive. In the existing market, commercially available titanium suboxide powder is mainly composed of titanium heptoxide powder, generally containing 3-10% by mass of titanium pentoxide, with other impurities being negligible. Repeated experimental verification has confirmed that the anode prepared using titanium heptoxide powder containing less than 10% titanium pentoxide exhibits essentially no change in chlorine evolution reaction and chlorine production efficiency compared to pure titanium heptoxide.

[0124] In one embodiment of the present invention, when iron oxide is used as an iron source to prepare anode material, it has been determined through repeated experiments that only 0.03g of iron oxide mixed with 2g of titanium dioxide powder is needed to produce the desired effect. Furthermore, it has been verified that when cleaning with dilute hydrochloric acid, only the unreacted excess material is removed, without affecting the subsequent preparation of anode products or the effect of the chlorine evolution reaction.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing an iron-doped sub-oxidized titanium electrode, characterized by The method comprises the following steps: Step 1: take 1 part by weight of titanium suboxide powder, add 0.5-5 parts by weight of ferrous sulfate heptahydrate into a ball mill tank, add quartz beads into the ball mill tank, seal the tank, and ball mill for more than 2 hours; Step 2: after the ball milling is completed, take out the powder, wash it with water for more than 5 times to remove unreacted ions, and then dry to obtain the iron-doped titanium suboxide powder; Step 3: configure Nafion reagent and isopropyl alcohol to obtain an isopropyl alcohol solution containing 3% Nafion reagent as a powder dispersant; Step 4: take 0.01 g of the iron-doped titanium suboxide powder prepared in Step 2, add it into 1 mL of the dispersant, use an ultrasonic instrument or a shaking instrument to uniformly disperse the powder in the dispersant, spray the uniformly dispersed mixed solution onto a 2 cm×2 cm carbon paper carrier, and then naturally air dry to obtain the iron-doped titanium suboxide electrode. The titanium suboxide powder is pure titanium tetraoxide or titanium tetraoxide powder containing not more than 10% by mass of titanium trioxide.

2. The method for preparing the iron-doped titanium suboxide electrode according to claim 1, wherein in Step 1, the 0.5-5 parts by weight of ferrous sulfate heptahydrate is 0.36-3.6 parts by weight of iron sulfate; or 0.29-4.25 parts by weight of ferric chloride; or 0.23-2.275 parts by weight of ferrous chloride. The method comprises the following steps:

3. A method for producing an iron-doped sub-oxidized titanium electrode, characterized by Step 1: take 1 part by weight of titanium suboxide powder, add 0.015-1 parts by weight of iron oxide into a ball mill tank, add quartz beads into the ball mill tank, seal the tank, and ball mill for more than 2 hours; Step 2: after the ball milling is completed, take out the powder, wash it with sufficient dilute hydrochloric acid to remove excess unreacted iron oxide, and then wash with water to remove unreacted ions to obtain the iron-doped titanium suboxide powder; Step 3: configure Nafion reagent and isopropyl alcohol to obtain an isopropyl alcohol solution containing 3% Nafion reagent as a powder dispersant; Step 4: take 0.01 g of the iron-doped titanium suboxide powder prepared in Step 2, add it into 1 mL of the dispersant, use an ultrasonic instrument or a shaking instrument to uniformly disperse the powder in the dispersant, spray the uniformly dispersed mixed solution onto a 2 cm×2 cm carbon paper carrier, and then naturally air dry to obtain the iron-doped titanium suboxide electrode. The titanium suboxide powder is pure titanium tetraoxide or titanium tetraoxide powder containing not more than 10% by mass of titanium trioxide.

4. The method for preparing the iron-doped titanium suboxide electrode according to any one of claims 1-3, wherein the ball milling time is 2-24 hours.

5. The iron-doped titanium suboxide electrode according to any one of claims 1-4, wherein the prepared iron-doped titanium suboxide electrode is used as an anode, a platinum electrode is used as a cathode, a saturated calomel electrode is used as a reference electrode, and seawater is used for electrolysis to produce an active chlorine gas through a chlorine evolution reaction.

6. The application of the iron-doped titanium suboxide electrode according to claim 5, wherein ​ ​ ​ The electrolysis device comprises an external power supply; the anode is an anode prepared by iron-doped sub-oxidized titanium powder on a carbon paper carrier, and a foamed nickel is used as the cathode; a sealing gasket in the reaction container is between the anode and the cathode, seawater or ballast water flows into the reaction container from the cathode side through a peristaltic pump, and after a short stay in the reactor, the seawater or ballast water flows back into the seawater or ballast water through the anode side.

7. The use of the iron-doped sub-oxidized titanium electrode according to claim 6, characterized in that: In the sunny and cloudless noon time, a solar panel with a size of 8.5 cm x 5.6 cm is used as the power supply, the voltage / current parameters of the power supply are 5 V / 160 mA; 300 mL of seawater is pumped out at a speed of 30 mL / min by using a peristaltic pump, and after 5 minutes of reaction in the electrolysis device, the log sterilization rate of the bacteria in the electrolyte is 7.

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