Method and device for treating polluted water in a river basin

Abstract

The present invention discloses a method and device for treating polluted water in a river basin, comprising the following steps: S1, contacting a hydrogel-solidified iron ion composite material with the polluted water in the river basin; S2, subjecting the polluted water in the river basin to electrolysis treatment under oxygen or aeration conditions, wherein the cathode used in the electrolysis treatment is a carbon-based cathode material; the carbon-based cathode material is coated with an air stone; and the current used in the electrolysis treatment is 2 to 5 mA / cm 2 The present invention provides a method for scalably treating polluted water bodies in river basins, which can efficiently and automatically remove toxic and harmful organic pollutants in dispersed water bodies such as lakes and rivers, and does not require pH control of the system or human intervention.

Description

Technical Field

[0001] The present invention relates to the technical field of organic wastewater treatment, in particular to a method and device for treating polluted water bodies in a river basin. Background Art

[0002] Low levels of antibiotics are widely detected in both wild and urban watersheds. Incidents of large-scale water pollution in wild rivers caused by transport accidents involving organic chemicals such as phenol are also frequently reported. However, existing technologies for addressing long-term, stable low-level antibiotics and other organic pollutants, as well as sudden organic pollution incidents, remain limited to traditional techniques of basic biochemical treatment, physical adsorption, and chemical dosing. Biochemical treatment, known as the activated sludge method, requires a relatively high level of biodegradable organic matter in the water and has a long treatment cycle. This technology is primarily used in existing sewage treatment plants. In actual field projects, the coupling of physical adsorption and biochemical degradation primarily involves the creation of artificial aquatic ecological islands or duckweed, where activated carbon adsorbs organic matter in the water and natural microorganisms in the soil degrade it. However, toxic and persistent organic matter cannot be biodegraded. Physical adsorption is also very limited in capacity and has a long cycle, failing to truly degrade organic matter. Chemical addition, such as potassium permanganate, is typically used to transport wastewater to treatment tanks, triggering large-scale oxidation reactions. However, this treatment technology is not only costly but also has limited capacity for ex situ, sequencing batch treatment. Electro-Fenton treatment is currently a popular and efficient, green treatment technology for difficult-to-degrade organic pollutants.

[0003] However, in the treatment of river basin water pollution, electro-Fenton treatment technology cannot be directly used for treatment. This is because the water conductivity in the river basin water body is extremely low, which greatly limits the current efficiency and the increase in energy consumption; secondly, due to the limitations of economic costs and process conditions, the size and shape of electrode materials are difficult to enlarge and adjust; it is difficult to develop a Fenton catalyst that is stable, free of secondary pollution, scalable and efficient, which is also a bottleneck in the current system material preparation.

[0004] In summary, it is necessary to develop a method and device for treating river water bodies, which not only solves problems such as low conductivity, secondary pollutants, low degradation rate, and high energy consumption (high current density), but also meets the needs of various scale devices and application scenarios. Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, in its first aspect, the present invention provides a method for treating polluted water in a river basin. This method can effectively improve the conductivity of degraded water and rapidly remove toxic and hazardous organic pollutants, such as antibiotics, from dispersed water bodies such as lake water.

[0006] The second aspect of the present invention also provides a device for treating polluted water in a river basin.

[0007] According to a first aspect of the present invention, a method for treating polluted water in a river basin is provided, comprising the following steps:

[0008] S1. contacting the hydrogel-solidified iron ion composite material with polluted water in the basin;

[0009] S2. Electrolysis treatment is performed on the polluted water in the watershed under oxygen or aeration conditions, wherein the cathode used in the electrolysis treatment is a carbon-based cathode material; the carbon-based cathode material contains gas stone; the current density used in the electrolysis treatment is 2-5 mA / cm 2 .

[0010] The method for treating polluted water in a river basin according to an embodiment of the present invention has at least the following beneficial effects:

[0011] Electrochemical advanced oxidation technology has high requirements for the conductivity of the degraded water body; however, the conductivity of the water body in the basin is very low, which greatly limits the current efficiency. The existing electrocatalytic oxidation technology cannot be used to treat polluted water bodies in the basin.

[0012] The present invention provides a method for treating polluted water bodies in river basins. The method can efficiently remove toxic and harmful organic pollutants in dispersed water bodies such as lakes and rivers without the need to control the pH of the system. The principle is as follows: the cathode is a carbon-based cathode material wrapped with an air stone. The air pump delivers air to the air stone. The oxygen in the air passes through and diffuses in the cathode catalytic material, so that in the three-phase reaction interface, the oxygen is reduced to H2O2. The hydrogel-cured iron ion composite material is rich in free iron ions (Fe 2+ / Fe 3+ ), Fe can be increased or decreased accordingly according to the change of hydrogen peroxide concentration. 2+ / Fe 3+ On the one hand, it improves the local conductivity of the electrocatalytic reaction; on the other hand, it is economical and can accurately control Fe 2+ / Fe 3+ The release of H2O2 allows for efficient activation and generates highly active hydroxyl radicals (·OH) to degrade organic matter, while also preventing secondary pollution caused by excessive iron ion emissions and the resulting iron sludge. Because the air stone is encased in a cathode carbon-based material, oxygen can diffuse across the material's inner and outer surfaces, increasing the reaction area several times and significantly boosting H2O2 production, thereby improving the ability to treat contaminated water.

[0013] According to some embodiments of the present invention, the hydrogel-cured iron ion composite material is prepared by the following method:

[0014] Polyvinyl alcohol, ferrous salt and water are mixed to undergo a hydrothermal reaction, followed by freezing, drying and heating. Thus, after freezing, drying and heating, the hydrogel surface of the present invention can be plasticized (hardened, plasticized) to prevent the hydrogel from decomposing and thus generating secondary pollutants.

[0015] According to some embodiments of the present invention, the mass ratio of the polyvinyl alcohol, ferrous salt and water is 2-6:1:20-50.

[0016] According to some embodiments of the present invention, the heating temperature is 75°C to 95°C.

[0017] According to some embodiments of the present invention, the freezing temperature is -15°C to -30°C.

[0018] According to some embodiments of the present invention, in the hydrogel-cured iron ion composite material, the concentration of iron ions released by the hydrogel is 1 to 5 ppm.

[0019] According to some embodiments of the present invention, the mass volume ratio of the hydrogel-solidified iron ion composite material to the polluted water in the basin is 5-15 mg / 60 mL. Therefore, the amount of the hydrogel-solidified iron ion composite material used is small and has a good degradation effect.

[0020] According to some embodiments of the present invention, the method for preparing the carbon-based cathode material comprises the following steps:

[0021] The carbon black and polytetrafluoroethylene are loaded on a stainless steel mesh and calcined under vacuum to obtain the product.

[0022] According to some embodiments of the present invention, the mass ratio of carbon black to polytetrafluoroethylene is 1:1-4, and the mass ratio of carbon black to polytetrafluoroethylene is 70 mg / cm 2 The load capacity determines the area size of the stainless steel mesh.

[0023] According to some embodiments of the present invention, the calcination temperature is 300-500°C.

[0024] According to some embodiments of the present invention, the calcination time is 30 min to 90 min.

[0025] According to some embodiments of the present invention, the electrolysis treatment lasts for 1 to 24 hours.

[0026] According to some embodiments of the present invention, the material of the anode used in the electrolytic treatment is selected from one or more of graphite rods, glassy carbon, boron-doped diamond, precious metals (such as platinum), and titanium-based precious metal coatings (such as IrO2, PbO2, and Ti4O7). According to a second aspect of the present invention, an apparatus for treating polluted water in a river basin is provided, comprising an electrolysis device; the electrolysis device comprises a reaction vessel, an electrode unit, an aeration device, and a power supply unit; the power supply unit is electrically connected to the electrode unit; the reaction vessel comprises a catalytic unit and an electrode unit; the electrode unit is provided with a cathode and an anode; the cathode is provided with an aeration device; a water inlet and a water outlet are provided on both sides of the reaction vessel; and the catalytic unit comprises a hydrogel-cured iron ion composite material.

[0027] The device for treating polluted water in a river basin according to an embodiment of the present invention has at least the following beneficial effects:

[0028] The device of the present invention can be applied to polluted water bodies in river basins to enhance local electrical conductivity and has a stronger sewage treatment capability at a lower current density.

[0029] According to some embodiments of the present invention, the area of ​​the carbon-based material of the cathode is not required and is adjusted according to specific application scenarios and effects.

[0030] According to some embodiments of the present invention, the power supply unit comprises a plurality of solar panels, which are electrically connected to each other in sequence, so that the energy for the electrolysis reaction comes from clean energy.

[0031] According to some embodiments of the present invention, the power supply unit may also provide a power source for the carrier.

[0032] According to some embodiments of the present invention, the electrolysis device of the present invention is supported on a carrier.

[0033] According to some embodiments of the invention, the carrier comprises a ship.

[0034] According to some embodiments of the present invention, the vessel further comprises a GPS positioning mainboard, a power motor and a propeller.

[0035] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0037] Figure 1 is a schematic diagram of a device according to embodiment 2 of the present invention;

[0038] Figure 2 is a graph showing the hydrogen peroxide yield and current efficiency of Example 1 of the present invention;

[0039] Figure 3 This is a rendering of the device according to embodiment 2 of the present invention for degrading antibiotics;

[0040] Figure 4 Graph showing changes in electrical conductivity of the reaction solution of the device system according to Example 2 of the present invention. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0042] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0043] Example 1

[0044] Example 1 provides a method for treating polluted water in a river basin; the method comprises the following steps:

[0045] Preparation of cathode material: stainless steel mesh as substrate with an area of ​​12.5 cm 2 , and evenly load carbon black and PTFE (polytetrafluoroethylene) catalytic materials thereon, and calcine at 340° C. under vacuum for 1 hour to obtain the obtained product.

[0046] Preparation of hydrogel-cured iron ion composite material: 4g PVA (polyvinyl alcohol) and 100mg FeSO4·7H2O were dissolved in 40mL ultrapure water, and after hydrothermal reaction for 12h, cast into a mold and frozen at -20℃, vacuum dried, and heated at 80℃ to obtain the composite material.

[0047] Example 1 studied the effect of cathode material wrapped gas stone on H2O2 yield and current efficiency. The specific experiment is as follows:

[0048] (1) Use an H-type electrolytic cell and add 60 ml of Na2SO4 (50 mM) electrolyte to each of the two electrodes. Use a three-electrode system, with the cathode cell containing the cathode material and the Ag / AgCl reference electrode, and the anode cell containing the graphite rod.

[0049] (2) Under the electrochemical workstation, a constant voltage of -1 V was applied to the working electrode, and clean air was delivered to the cathode gas stone by an air pump. After one hour of reaction, 1 mL of the solution was aspirated and filtered through a 0.22 μm filter head, and then added to 15 mL of 0.5 mM cerium sulfate solution. After the color reaction, the H2O2 production was calculated based on the characteristic peak intensity at 317 nm using an ultraviolet spectrophotometer.

[0050] The results are as follows Figure 2 As shown: Working modes 1 and 3 are the H2O2 yield and current efficiency when oxygen and air are introduced through the wrapped air stone and wrapped by the cathode material; Working modes 2 and 4 are the yield and current efficiency of oxygen and air diffused directly from the air stone in the solution without air stone wrapping; It can be seen that the present invention uses cathode material to wrap the air stone, and oxygen diffuses on the inner and outer surfaces of the material, which increases the reaction area several times and greatly improves the yield and current efficiency.

[0051] Example 2

[0052] Example 2 provides a device for treating polluted water bodies in a river basin. The device can be powered entirely by solar energy and equipped with GPS, which can automatically cruise and treat polluted water bodies. The schematic diagram of the device is shown in the figure below. Figure 1 As shown, the invention comprises a hull and an electrolysis device supported on the hull; the electrolysis device comprises a reaction vessel, an electrode unit, an aeration device, a power supply unit, and an air inlet; the air inlet is connected to the aeration device, and the reaction vessel comprises a catalytic unit; a water inlet and a water outlet are provided on both sides of the reaction vessel; the reaction vessel contains a hydrogel-cured iron ion composite material; the electrode unit comprises a cathode and an anode. The cathode is the cathode prepared in Example 1, and the anode is a graphite rod.

[0053] Figure 1 The principle is as follows: the power supply unit supplies power to the boat's kinetic energy system, electrolysis device, and other auxiliary electronic components. Air is pumped from the exposed air pipe on the boat's surface to the surface of the cathode carbon-based material, reducing the oxygen in the air to H2O2. A hydrogel-solidified iron ion composite material (yellow block particles in the picture) is added to the reaction system. The hydrogel can increase or decrease Fe according to the concentration of hydrogen peroxide. 2+ / Fe 3+ The release of Fe can improve the local conductivity of the electrocatalytic reaction while also more economically and accurately controlling the 2+ / Fe 3+ The release of Fe 3+ Can be reduced to Fe on the surface of cathode material 2+ , can also be reduced to Fe by H2O2 2+ , thereby increasing the content of Fe 2+ This further promotes the catalytic generation of highly active hydroxyl radicals (·OH) from H2O2, thereby rapidly oxidizing organic pollutants. As the boat moves forward, sewage continuously flows in and out of the reaction vessel's inlet and outlet, thereby being degraded. Figure 1 Figure a shows the upper surface of the hull covered with solar panels, air pipes, and male and female electrode terminals; Figure 1Figure b shows the reaction vessel of the electrolysis device under the side of the hull, as well as electronic components such as the ammeter and voltmeter at the stern, which facilitate monitoring and recording the working status of the electrocatalytic system.

[0054] The device was applied to the removal of antibiotics in lake water. The test steps are as follows:

[0055] 1) The aforementioned cathode and anode electrodes are placed in a reaction vessel at the bottom of the boat. A xenon lamp is used to simulate sunlight. The height of the light source irradiating the solar panel on the top of the boat is controlled to control the applied electrocatalytic voltage to a range of 4.5-5.5V.

[0056] 2) Add 300 mg of the hydrogel-cured iron ion composite material to the reaction vessel. Place the boat in a 30 cm × 17 cm × 20 cm water tank with 2 L of sewage (20 ppm tetracycline hydrochloride). Turn on the air pump and light source. Aspirate 4 mL of the reaction solution at different reaction time periods. After filtering through a 0.22 μm filter, detect the solution using a UV spectrophotometer, and calculate the antibiotic degradation effect based on the absorption intensity of the characteristic peak at 357 nm.

[0057] The results are as follows Figure 3 and Figure 4 Shown: Among them Figure 3 In the table, Lake represents lake water, and its conductivity is about 343uS / cm.

[0058] from Figure 3 It can be seen that the removal rate of antibiotics in lake water by the present invention is as high as 90%, and it has a good degradation effect.

[0059] Figure 4 In this paper, hydrogel represents hydrogel; ORR Catalyst represents cathode catalytic material. The changes in solution conductivity during the reaction in a 60mL single-cell electrolyzer with and without the addition of hydrogel and with or without cathode material demonstrate that during the degradation of the boat, the local conductivity is significantly higher than that outside the reaction system. This also demonstrates that the present invention, by introducing a hydrogel-cured iron ion composite material, solves the problems of low current efficiency and high energy consumption in low-conductivity water for the first time. Furthermore, the release of ferrous ions is very low, making secondary pollution less likely.

[0060] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A method for treating polluted water in a river basin, characterized in that: The steps include: S1. contacting the hydrogel-solidified iron ion composite material with polluted water in the basin; S2. Electrolysis treatment is performed on the polluted water in the watershed under oxygen or aeration conditions, wherein the cathode used in the electrolysis treatment is a carbon-based cathode material; the carbon-based cathode material is coated with an air stone; and the current density used in the electrolysis treatment is 2-5 mA / cm 2 ; The hydrogel-cured iron ion composite material is prepared by the following method: The polyvinyl alcohol, ferrous salt and water are mixed to carry out hydrothermal reaction, and then the mixture is frozen, dried and heated in sequence to obtain the product.

2. The method for treating polluted water in a river basin according to claim 1, characterized in that: In the hydrogel-cured iron ion composite material, the concentration of iron ions released by the hydrogel is 1 to 5 ppm.

3. The method for treating polluted water in a river basin according to claim 1, characterized in that: The method for preparing the carbon-based cathode material comprises the following steps: The carbon black and polytetrafluoroethylene are loaded on a stainless steel mesh and calcined under vacuum to obtain the product.

4. The method for treating polluted water in a river basin according to claim 1, characterized in that: The electrolysis treatment time is 1 to 24 hours.

5. The method for treating polluted water in a river basin according to claim 1, characterized in that: The anode material used in the electrolytic treatment is selected from one or more of graphite rods, glassy carbon, boron-doped diamond, and precious metals.

6. The method for treating polluted water in a river basin according to any one of claims 1 to 5, characterized in that: It also includes a device for implementing the method described in any one of claims 1 to 5, the device comprising an electrolysis device; the electrolysis device comprising a reaction vessel, an electrode unit, an aeration device and a power supply unit; the power supply unit is electrically connected to the electrode unit; the reaction vessel comprises a catalytic unit and an electrode unit; the electrode unit is provided with a cathode and an anode; the cathode is provided with an aeration device; water inlets and outlets are provided on both sides of the reaction vessel; the catalytic unit comprises a hydrogel-solidified iron ion composite material.

7. The method for treating polluted water in a river basin according to claim 6, characterized in that: The power supply unit is composed of a plurality of solar panels; the plurality of solar panels are electrically connected in sequence.

8. The method for treating polluted water in a river basin according to claim 6, characterized in that: The carrier of the device includes a ship.

9. The method for treating polluted water in a river basin according to claim 8, characterized in that: The boat also includes a GPS positioning mainboard, a power motor and a propeller.

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