Oily wastewater-oriented forward osmosis membrane purification and electrolysis coupling hydrogen production integrated device and application

Abstract

The invention belongs to the technical field of recycling of clean energy and resources, and particularly relates to a forward osmosis membrane purification and electrolysis coupling hydrogen production integrated device for oily wastewater and application, and an inorganic forward osmosis membrane with good performance and corrosion resistance and an electrode with high conductivity and durability are coupled and used in a double-cell electrolytic tank. The combined device gives full play to the separation capacity of the membrane and the reaction characteristics of the electrode, so that the whole system can efficiently produce hydrogen in the oil-containing wastewater, not only improves the overall hydrogen production efficiency, but also has the advantages of simplicity and convenience in operation and quick response, has good performance in the aspect of economy, reduces the production cost, and is suitable for industrial production. The method is expected to play an important role in large-scale application, and a new opportunity is brought to production and utilization of hydrogen energy. In addition, the device is good in stability, can be repeatedly used, is wide in application range, and has a wide application prospect in the field of water treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of clean energy and resource recycling, and particularly relates to a forward osmosis membrane purification and electrolysis coupled hydrogen production integrated device for oil-containing wastewater and application. BACKGROUND

[0002] With the development of industry, oil-containing wastewater is widely present in industrial production and daily life. If it is directly discharged without proper treatment, its harmfulness cannot be ignored. Oil substances in wastewater can penetrate into water bodies and soil, causing persistent pollution. Conventional treatment technologies (such as coagulation, flocculation, gravity sedimentation and oil skimming) have certain effects on floating oil and dispersed oil, but they often fall short when dealing with highly stable emulsified oil. These tiny oil droplets are wrapped by surfactants to form stable colloidal systems, have a density similar to that of water bodies and are often charged on the surface, making them difficult to be effectively captured and removed by simple physical separation or chemical flocculation. How to properly handle and realize resource utilization of these oil-containing wastewater has become a core challenge in the treatment of oil-containing wastewater. Green hydrogen, as a clean energy produced by electrolysis of water through renewable energy, is increasingly highlighting its importance and is expected to become the core support of future energy transformation. In recent years, the technology of electrolysis of water to produce hydrogen has been widely used in hydrogen energy production due to its relatively simple equipment structure, convenient maintenance and high hydrogen production efficiency. However, this technology still has defects such as corrosion and deactivation of membrane materials, which seriously limits the long-term stable operation of water electrolysis to produce hydrogen. Therefore, it is urgent to explore and adopt new methods to effectively solve the above problems.

[0003] To address the aforementioned challenges, the coupled treatment of oily wastewater using membrane distillation and electrolysis for hydrogen production has attracted widespread attention. This technology promises to efficiently demulsify and deeply purify wastewater while simultaneously producing high-purity hydrogen, providing a new approach to solving the problem of emulsified oil removal and achieving resource recovery. First, the hydrophobic microporous membrane utilizes the vapor pressure difference across its surface to force water in the feed solution to convert into water vapor, which diffuses to the electrolyte side and recondenses into liquid. This transforms water bodies unsuitable for electrolysis—especially oily wastewater with complex compositions and rich in pollutants such as oil—into usable feed water for hydrogen production. Subsequently, electrodes perform in-situ electrolysis to produce hydrogen in the driving liquid pool. However, the oil in the wastewater easily wets and fouls the hydrophobic membrane, severely weakening the efficiency and stability of the membrane distillation process, becoming a key bottleneck restricting the technology's ability to treat such wastewater and couple it with electrolysis for hydrogen production. Against the backdrop of innovation and advancement in hydrogen energy technology, developing more efficient hydrogen production technologies has become a research hotspot in the scientific research field. However, most existing hydrophobic membrane materials suffer from wetting, fouling, and temperature polarization problems, which are particularly pronounced and urgently need to be overcome when dealing with oily wastewater. Therefore, there is an urgent need to develop new membrane materials and technologies that can effectively resist oil pollution and maintain long-term stable operation, in order to promote the application of electrolytic hydrogen production in a wider range of fields, including oily wastewater treatment, to meet the energy needs of industry and society and address the challenges of water scarcity. Summary of the Invention

[0004] This invention aims to address some key shortcomings of the existing technologies, particularly those that limit their application, such as the susceptibility of membrane materials to corrosion and degradation during operation. Based on this, this invention proposes a device for hydrogen production based on the coupling of an inorganic forward osmosis membrane and electrolysis technology. This method is simple to operate, highly efficient, and has the potential for large-scale application, solving the problem of only being able to produce hydrogen using specific types of water.

[0005] To achieve the above objectives, the first aspect of the present invention provides an integrated device for forward osmosis membrane purification and electrolytic hydrogen production coupled with oily wastewater, the device comprising a feed tank, an electrolytic hydrogen production device, and a gas collection device.

[0006] The forward osmosis water collection unit is located between the feed tank and the electrolysis hydrogen production unit. The unit includes a core component, an inorganic forward osmosis membrane, which can stably extract water from various harsh water bodies and transfer water from the feed tank to the electrolysis cell side. This inorganic forward osmosis membrane possesses excellent corrosion resistance and high mechanical strength, enabling long-term operation in various harsh water bodies. Simultaneously, it can withstand the reactive oxygen species generated during electrolysis on the electrolysis cell side, avoiding the oxidative degradation problems of organic membranes. When water in the feed solution is filtered through the membrane, the obtained water molecules are guided through the membrane into the driving solution, enabling the extraction of water from different water bodies and achieving efficient utilization of water resources. The water is then used in the electrolysis reaction to produce hydrogen.

[0007] The electrolytic hydrogen production device includes an electrolytic cell, an ion exchange membrane, a cathode, and an anode. The ion exchange membrane is located inside the electrolytic cell along with the cathode and anode. The ion exchange membrane is disposed between the cathode and the anode to block gas but allow ion exchange.

[0008] The gas collection device is used to collect the generated hydrogen and oxygen.

[0009] Furthermore, the forward osmosis water collection unit is located at the end of the feed tank, and the electrolysis hydrogen production device is located at the end of the forward osmosis water collection unit.

[0010] Furthermore, the raw material pool is equipped with an inlet and an outlet.

[0011] Furthermore, the inorganic forward osmosis membrane is an inorganic composite membrane prepared from one or more novel nanomaterials, such as carbon nanotubes and graphene-like materials (e.g., graphene oxide, graphene quantum dots, and reduced graphene oxide). The pore size of the inorganic forward osmosis membrane ranges from 0.1 to 2 nm, preferably from 0.3 to 1 nm. For example, the inorganic forward osmosis membrane is a reduced graphene oxide / carbon nanotube membrane, which is prepared by first coating carbon nanotubes onto a 0.45 μm microporous filter membrane using vacuum filtration, then vacuum filtering graphene oxide onto the carbon nanotubes, and finally reducing it with ascorbic acid to obtain the reduced graphene oxide / carbon nanotube membrane. The mass ratio of carbon nanotubes to graphene oxide is 200:1, and the mass ratio of carbon nanotubes to ascorbic acid is 1:1.

[0012] Furthermore, the raw material pool contains a raw material solution, and the selective layer of the inorganic forward osmosis membrane faces the raw material pool (raw material solution); the osmotic pressure of the electrolyte in the electrolytic cell should be higher than the osmotic pressure of the raw material solution in the raw material pool.

[0013] Furthermore, the electrolytic hydrogen production device also includes a power source, with the negative terminal of the power source connected to the cathode and the positive terminal connected to the anode.

[0014] Furthermore, the power source can be one or more combinations of grid power supply, electrochemical workstation power supply, wind power generation, and solar power generation.

[0015] Furthermore, the device is a sealed device.

[0016] Furthermore, the electrolytic hydrogen production device adopts an alkaline water electrolysis process, and the electrolyte is an alkaline solution, preferably a 20-40 wt% KOH solution, more preferably a 25-30 wt% KOH solution; the cathode and anode materials are one or more of nickel-based materials and their alloys (such as nickel (which can be foamed nickel), cobalt, iron, titanium, molybdenum and their alloys), precious metals (platinum, iridium, ruthenium, etc.), and transition metals; the ion exchange membrane is a commercially available anion exchange membrane.

[0017] Furthermore, the electrolytic cell, cathode, and ion exchange membrane constitute a hydrogen gas-liquid separation device, the electrolytic cell, anode, and ion exchange membrane constitute an oxygen gas-liquid separation device, the gas collection device includes a hydrogen collection device and an oxygen collection device, the hydrogen gas-liquid separation device is connected to the hydrogen collection device, and the oxygen gas-liquid separation device is connected to the oxygen collection device.

[0018] A second aspect of this invention provides the application of the above-mentioned hydrogen production device in producing hydrogen from oily wastewater. The oily wastewater includes various types of oily water such as slaughterhouse wastewater, school canteen wastewater, and emulsified wastewater from mechanical processing. The application method is as follows:

[0019] The wastewater to be treated is added to the raw material tank. After the wastewater is treated by an inorganic forward osmosis membrane, the resulting permeate is transported to the electrolytic cell. In the dual-electrode system, the cathode and anode are placed in the electrolyte, and the water in the raw material solution is used as the raw material to carry out the electrolysis of water to produce hydrogen.

[0020] Furthermore, the voltage range is 0.5 to 5V, preferably 1.0V to 2.5V; the current range is 10mA to 1A.

[0021] Furthermore, the raw material solution used in the testing process is either pure water or oily wastewater.

[0022] This invention utilizes a coupling method between inorganic forward osmosis membranes and electrolysis technology to achieve efficient hydrogen production. A high-performance, corrosion-resistant inorganic forward osmosis membrane is coupled with highly conductive and durable electrodes in a dual-cell electrolysis cell. This combined device fully leverages the membrane's separation capabilities, enabling the entire system to efficiently produce hydrogen in various water bodies. It not only improves overall hydrogen production efficiency but also offers advantages such as ease of operation and rapid response. Furthermore, it demonstrates excellent economic performance, reducing production costs and showing potential for large-scale application. In the future, with continuous technological advancements and optimization, this device is expected to play a significant role in large-scale applications, bringing new opportunities for hydrogen energy production and utilization. In addition, the device exhibits good stability, reusability, and a wide range of applications, showing broad prospects in the field of water treatment.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The method of this invention achieves efficient hydrogen production by combining simple and reliable membrane technology with electrolysis technology. It is easy to operate, reacts rapidly, is inexpensive, and possesses good corrosion resistance. It can achieve in-situ electrolysis to produce hydrogen, demonstrating great potential for large-scale applications.

[0025] 2. The inorganic forward osmosis membrane used in the method of the present invention is prepared using common materials, which are easy to obtain and have a simple and easy preparation process, further enhancing its practicality and operability.

[0026] 3. The device coupled by the method of the present invention has a high hydrogen production efficiency. Compared with other hydrogen production methods, the device shows broad application prospects and significant advantages.

[0027] 4. The coupling device of this invention has low energy consumption and low investment. The forward osmosis process does not require external high pressure, reducing pretreatment energy consumption; the electrolysis unit can precisely process the concentrate, avoiding the high power consumption of full-volume electrolysis; at the same time, the active free radicals generated by electrolysis can clean the inorganic forward osmosis membrane online, reducing the frequency of chemical cleaning and extending membrane life.

[0028] 5. The device coupled by the method of the present invention has good stability and can be recycled multiple times in a high efficiency, thereby significantly improving its economy and sustainability.

[0029] 6. The coupling device of the present invention has strong adaptability, can operate stably in a pH range of 2 to 12, and is suitable for various water bodies, giving it broad application prospects in the field of water treatment and making it beneficial for practical applications. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the integrated forward osmosis membrane purification and electrolytic coupling hydrogen production device for oily wastewater in Example 1.

[0031] Figure 2 This is a physical image of the inorganic forward osmosis membrane (left) and cathode (right) in the integrated forward osmosis membrane purification and electrolytic coupling hydrogen production device for oily wastewater in Example 1.

[0032] Figure 3 The voltage change of the integrated forward osmosis membrane purification and electrolytic coupling hydrogen production device for oily wastewater in Example 2 is shown under a 0.4A operating condition.

[0033] Figure 4 The conductivity change on the feed solution side of the integrated hydrogen production device for oily wastewater, which combines forward osmosis membrane purification and electrolytic coupling, is shown in Example 5 under operating conditions of 0.4A.

[0034] Explanation of symbols in the attached drawings:

[0035] 1. Raw material tank, 2. Forward osmosis unit, 3. Cathode, 4. Ion exchange membrane, 5. Anode, 6. Power supply, 7. Oxygen collection device, 8. Hydrogen collection device. Detailed Implementation

[0036] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0037] Example 1

[0038] like Figure 1 and Figure 2 As shown in the figure, this embodiment provides an integrated device for forward osmosis membrane purification and electrolysis coupled hydrogen production for oily wastewater, comprising: a feed tank 1, a forward osmosis unit 2, an electrolysis cell 3, a cathode 4, an ion exchange membrane 5, an anode 6, a power supply 7, a hydrogen collection device 8, and an oxygen collection device 9. The feed tank 1 and the electrolysis cell 3 are respectively equipped with an inlet and an outlet; the forward osmosis unit 2 includes a core component, an inorganic forward osmosis membrane, which is a reduced graphene oxide / carbon nanotube membrane (prepared by: first using 10 mL of a 1 wt% carbon nanotube aqueous dispersion, filtering the carbon nanotubes to 0.45 μm). A carbon nanotube membrane was obtained on an MCE aqueous hybrid fiber microporous membrane (50 mm in diameter). Then, graphene oxide was filtered onto the carbon nanotube membrane using 10 mL of a 50 mg / L graphene oxide aqueous dispersion. Finally, the filtered membrane was placed in 50 mL of a 2 g / L ascorbic acid aqueous solution and reduced at 60°C for 10 h to obtain a reduced graphene oxide / carbon nanotube membrane. This membrane was placed between the raw material tank 1 and the electrolytic cell 3, blocking ions such as calcium, magnesium, sodium, and chloride ions from the raw material tank from permeating into the electrolytic cell, but allowing water to permeate. The selective layer faced the raw material tank 1 and was sealed to its edges. A 30 mm diameter FKB-PK-75 anion exchange membrane 5 was fitted with a foamed nickel cathode 4 (2 × 2 cm). 2) and platinum sheet electrode 6 (anode, 2×2cm) 2 Between the cathode 4 and anode 6, gas is prevented from flowing from the cathode 4 to the anode 6 or vice versa, but ion exchange is allowed; power supply 7 supplies power to the device, with the positive terminal connected to the anode 6 and the negative terminal connected to the cathode 4; the generated hydrogen and oxygen are collected by hydrogen collection device 8 and oxygen collection device 9, respectively; adjacent components are connected as a whole and sealed at the edges. Raw material tank 1 contains raw material solution, and electrolytic cell 3 contains electrolyte.

[0039] Example 2

[0040] The voltage change of the device in Example 1 under 0.4A operating conditions. The feed solution was oily wastewater from a slaughterhouse (oil concentration of 1600 mg / L, pH 5.5), and the electrolyte was a 30% KOH solution. Under a constant current of 0.4A, the device operated for 2 hours, with the oil, water, and electrolyte continuously circulating during operation. The volume of oil and water participating in the reaction was 50 mL, and the volume of electrolyte was 50 mL. Under these conditions, the theoretical hydrogen production was 425 mL, and the device collected 369 mL of hydrogen gas, meaning the actual hydrogen production was approximately 86.8% of the theoretical value.

[0041] like Figure 3 As shown, in this embodiment, the voltage remains stable under a current of 0.4A.

[0042] Example 3

[0043] The difference between this embodiment and Embodiment 2 lies in the use of wastewater from a school cafeteria (oil concentration 500 mg / L, pH 6.2) as the raw material solution. Under these conditions, the theoretical hydrogen production from the wastewater is 334 mL, and the device collected 279 mL of hydrogen gas, meaning the actual hydrogen production was approximately 83.5% of the theoretical value.

[0044] Example 4

[0045] The difference between this embodiment and Embodiment 2 lies in the use of a machining emulsified wastewater (oil concentration 5500 mg / L, pH 9.5) as the raw material solution. Under these conditions, the theoretical hydrogen production from the machining wastewater is 328 mL, and the device collected 272 mL of hydrogen gas, resulting in an actual hydrogen production of approximately 82.9% of the theoretical value.

[0046] Example 5

[0047] Example 1 illustrates the variation in conductivity of the device in different water bodies. Under a constant current of 0.4 A, the device operated for 2 hours each time. The raw material solutions were oily wastewater from a slaughterhouse (oil concentration 1600 mg / L, pH 5.5), wastewater from a school canteen (oil concentration 500 mg / L, pH 6.2), and emulsified wastewater from metal cutting processes (oil concentration 5500 mg / L, pH 9.5). The electrolyte was a 30% KOH solution. The volume of the raw material solution and the electrolyte involved in the reaction was 50 mL. During electrolysis, samples were taken at specific time intervals (0 min, 30 min, 60 min, 90 min, 120 min), and the conductivity of the solution was immediately measured using a conductivity meter. The results are shown below. Figure 4 As shown.

[0048] like Figure 4 As shown, during the operation of the device, the conductivity on the feed liquid side increases with the increase of operating time, which indicates that water molecules are transferred to the cathode electrolysis cell side through osmotic pressure, thereby providing water for electrolysis.

Claims

1. An integrated device for forward osmosis membrane purification and electrolytic hydrogen production coupled with oily wastewater, characterized in that: The device includes a raw material pool, a forward osmosis water collection unit, an electrolysis hydrogen production device, and a gas collection device. The forward osmosis water collection unit is located between the feed tank and the electrolysis hydrogen production device. The forward osmosis water collection unit includes an inorganic forward osmosis membrane, which transfers water from the feed tank to the electrolysis tank side. The electrolytic hydrogen production device includes an electrolytic cell, an ion exchange membrane, a cathode, and an anode. The ion exchange membrane, along with the cathode and anode, is located within the electrolytic cell, and the ion exchange membrane is disposed between the cathode and the anode. The gas collection device is used to collect the generated hydrogen and oxygen.

2. The apparatus according to claim 1, characterized in that: The inorganic forward osmosis membrane is an inorganic forward osmosis membrane prepared from one or more materials such as carbon nanotubes and graphene, with a pore size of 0.1 to 2 nm.

3. The apparatus according to claim 1, characterized in that: The selective layer of the inorganic forward osmosis membrane faces the raw material pool; the osmotic pressure of the raw material solution in the raw material pool is lower than the osmotic pressure of the electrolyte in the electrolytic cell.

4. The apparatus according to claim 1, characterized in that: The forward osmosis water collection unit is located at the end of the feed tank, and the electrolysis hydrogen production device is located at the end of the forward osmosis water collection unit.

5. The apparatus according to claim 1, characterized in that: The electrolytic hydrogen production device adopts an alkaline water electrolysis process, the electrolyte is an alkaline solution, and the cathode and anode materials are one or more of nickel-based materials and their alloys, noble metals, and transition metals.

6. The apparatus according to claim 1, characterized in that: The electrolytic hydrogen production device also includes a power source, with the negative terminal of the power source connected to the cathode and the positive terminal connected to the anode.

7. The apparatus according to claim 6, characterized in that: The power source can be one or more combinations of grid power supply, electrochemical workstation power supply, wind power generation, and solar power generation.

8. The apparatus according to claim 1, characterized in that: The electrolytic cell, cathode, and ion exchange membrane constitute a hydrogen gas-liquid separation device, the electrolytic cell, anode, and ion exchange membrane constitute an oxygen gas-liquid separation device, the gas collection device includes a hydrogen collection device and an oxygen collection device, the hydrogen gas-liquid separation device is connected to the hydrogen collection device, and the oxygen gas-liquid separation device is connected to the oxygen collection device.

9. The application of the apparatus according to any one of claims 1-8 in the production of hydrogen from oily wastewater.

10. The application according to claim 9, characterized in that, The application method is as follows: The wastewater to be treated is added to the raw material tank. After the wastewater is treated by an inorganic forward osmosis membrane, the resulting permeate is transported to the electrolytic cell to carry out the electrolysis of water to produce hydrogen.

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