Oil-containing radioactive waste liquid deoiling electrolytic bath and preparation method and treatment system thereof

Abstract

The invention provides an oil removal electrolytic bath for oil-containing radioactive waste liquid. The oil removal electrolytic bath comprises an FRPP matrix layer, a modified FRPP transition layer, a flame-retardant adhesive layer and a modified enhanced high-silica cloth layer which are sequentially compounded from inside to outside, the modified FRPP transition layer is of a composite layered structure which takes FRPP as a base material and is embedded with a silane interface bridging medium and a thermoplastic elastomer; the flame-retardant adhesive layer is a flame-retardant silicone-based adhesive layer; the modified enhanced high-silica cloth layer is of a composite enhanced structure and comprises a high-silica cloth base material and glass fiber gridding cloth or a honeycomb structure embedded in the base material, and a silane interface treatment layer or a low-temperature plasma treatment layer is arranged on the inner surface of the high-silica cloth base material. The invention further provides a preparation method of the electrolytic bath and an oil-containing radioactive waste liquid treatment system. The electrolytic cell is reliable in structure, can synergistically realize pressure resistance, flame retardance and insulation performance, and provides a reliable innovative equipment scheme for deep oil removal of the oil-containing radioactive waste liquid.

Description

Technical Field

[0001] This invention relates to the field of nuclear industry waste liquid treatment equipment technology, and in particular to an oil removal electrolytic cell for oily radioactive waste liquid, its preparation method and treatment system. Background Technology

[0002] Large quantities of oil-containing radioactive waste are generated during nuclear industry production, nuclear facility decommissioning, and radioactive waste disposal. The oil phase in this type of waste is mainly composed of various organic compounds. The presence of these organic substances seriously interferes with the recovery and treatment of radionuclides and may cause scaling and corrosion of equipment, threatening the stable operation of the system. Therefore, removing these organic components from the waste is a key step in achieving efficient treatment.

[0003] Electrocatalytic oxidation for deep oil removal is currently the mainstream solution for treating oily radioactive waste. It decomposes organic matter by generating hydroxyl radicals (·OH) through electrode reactions, producing virtually no secondary waste and possessing broad engineering application prospects. However, the electrocatalytic oxidation electrolyzer, as the core equipment of this technology, is limited by the specific application environment and operating principle, and must simultaneously meet three stringent performance requirements: (1) Insulation requirements: The electrolytic cell must be effectively isolated from the external power supply system to avoid short circuit faults caused by the conductivity of the cell; at the same time, in order to ensure the personal safety of the operators, the cell must have reliable insulation performance to prevent the risk of electric shock. (2) Pressure resistance requirements: During the electrolysis process, gases such as H2, N2, and CO2 will be generated, and the waste liquid needs to be vented and the reaction enhanced through the circulation system to avoid the accumulation of gas in the microchannel of the electrolytic cell and affect the treatment efficiency. Therefore, the system needs to provide a driving force of ≥0.3MPa, and the electrolytic cell needs to have sufficient structural strength to withstand this pressure. (3) Flame retardancy requirements: Due to the closed design of the radioactive waste liquid treatment system, hydrogen gas leaked during the electrolysis process is prone to accumulate in the closed space, posing a risk of deflagration. Therefore, the material of the electrolytic cell must meet the UL94 V-2 level or above flame retardant standard to reduce the risk of fire.

[0004] Currently, there is no technical solution in the research and development of electrolytic cells for treating oily radioactive waste that can simultaneously meet the above three performance requirements. Existing related electrolytic cells and material improvements have significant defects. For example, electrolytic cells made of single material, such as glass fiber reinforced polypropylene (FRPP), have good insulation and basic mechanical properties, but their flame retardancy is insufficient and cannot meet the UL94 V-2 flame retardancy requirements. Furthermore, directly applying a flame retardant coating will result in poor interlayer adhesion and cracking under pressure as the substrate expands. Adding flame retardants can improve flame retardancy, but it will significantly weaken the material's mechanical properties, leading to a decrease in pressure resistance and failing to meet the requirement of ≥0.3MPa. Electrolytic cells made of fiberglass have acceptable flame retardancy, but the structural strength of the material itself is limited, making it difficult to withstand pressures of 0.3MPa and above. Electrolytic cells made of all stainless steel have high mechanical strength and strong pressure resistance, but the conductivity of the metal material means that it has no insulation properties at all.

[0005] In summary, the existing technology lacks an electrolytic cell structure that can simultaneously meet the requirements of insulation, pressure resistance (≥0.3MPa), and flame retardancy (UL94V-2 level), which severely limits the large-scale application of electrocatalytic oxidation deep oil removal technology in the treatment of oily radioactive waste liquid.

[0006] Therefore, there is an urgent need to develop an electrolytic cell with a reliable structure that can synergistically achieve pressure resistance, flame retardancy, and insulation properties. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an oil removal electrolytic cell for oily radioactive waste liquid, its preparation method and treatment system. The electrolytic cell has a reliable structure and can synergistically achieve pressure resistance, flame retardancy and insulation performance.

[0008] The present invention solves the above-mentioned technical problems by adopting the following technical solutions: An oil removal electrolytic cell for oily radioactive waste liquid includes, from the inside out, a FRPP matrix layer, a modified FRPP transition layer, a flame-retardant adhesive layer, and a modified reinforced high-silica cloth layer. The modified FRPP transition layer is a composite layered structure with FRPP as the substrate, embedded with a silane-based interfacial bridging medium and a thermoplastic elastomer. The flame-retardant adhesive layer is a flame-retardant silicone-based adhesive layer. The modified reinforced high-silica cloth layer is a composite reinforced structure, including a high-silica cloth substrate and a glass fiber mesh or honeycomb structure embedded inside the substrate. The inner surface of the high-silica cloth substrate is provided with a silane-based interfacial treatment layer or a low-temperature plasma treatment layer.

[0009] As one of the preferred embodiments of the present invention, the thickness of the FRPP matrix layer is 3~10mm, and its flexural modulus is ≥2900MPa.

[0010] As one of the preferred embodiments of the present invention, the thickness of the modified FRPP transition layer is 0.3~1.0 mm; and the silane-based interfacial bridging medium is KH-550 type silane coupling agent, which accounts for 1~5% of the mass of the modified FRPP transition layer; the thermoplastic elastomer is EVA elastomer, which accounts for 3~8% of the mass.

[0011] As one of the preferred embodiments of the present invention, the flame-retardant silicone-based adhesive layer has a thermal decomposition temperature ≥300℃, a flame retardant rating of UL94 V-2, and a layer thickness of 0.5~2.0mm.

[0012] As one of the preferred embodiments of the present invention, in the modified and reinforced high-silica cloth layer: The thickness of the high-silica cloth substrate is 1~4mm, and the oxygen index is ≥45%; The silane-based interface treatment layer is a KH-570 type silane coupling agent coating layer with a thickness of 50~200μm; The pore size of the fiberglass mesh is 2~5mm, and the wire diameter is 0.5~1.2mm; The honeycomb structure has a pore size of 3~8mm and a wall thickness of 0.3~0.8mm.

[0013] As one of the preferred embodiments of the present invention, the outer surface of the FRPP matrix layer facing the modified FRPP transition layer is further provided with a rough surface structure, which is formed by sandblasting or mechanical grinding, and its surface roughness Ra is 40~60μm.

[0014] A method for preparing the above-mentioned electrolytic cell includes the following steps: (1) Surface treatment of the substrate: The outer surface of the FRPP substrate layer is sandblasted or mechanically polished to form a rough surface, and then the surface dust is removed with compressed air; (2) Transition layer composite: FRPP, silane-based interfacial bridging medium and thermoplastic elastomer are blended and hot-pressed into a modified FRPP transition layer, which is then bonded to the outer surface of the FRPP matrix layer after step (1). (3) Adhesive coating: A flame-retardant silicone-based adhesive is uniformly coated on the outer surface of the modified FRPP transition layer to form a flame-retardant adhesive layer; (4) Pretreatment of high silica cloth: The inner surface of the high silica cloth substrate is treated with silane interface treatment or low temperature plasma treatment to form a treatment layer. Then, glass fiber mesh or honeycomb structure is embedded in the high silica cloth substrate to obtain a modified and reinforced high silica cloth layer. (5) Composite curing: The modified and reinforced high silica cloth layer obtained in step (4) is coated on the outer surface of the flame retardant adhesive layer. After removing air bubbles, pressure is applied, and an integrated electrolytic cell is formed through a step curing process.

[0015] As one of the preferred embodiments of the present invention, in step (3), the coating thickness of the flame-retardant silicone-based adhesive is 0.5~1.5mm. If a second coating is required, the second coating is performed after drying in a ventilated environment at room temperature for 12~24 hours, and the total adhesive layer thickness does not exceed 2.0mm.

[0016] As one of the preferred embodiments of the present invention, in step (5), the pressure applied is 0.05~0.15MPa, and the step curing process is: pre-curing at 35~45℃ for 4~8 hours, and then heating to 75~85℃ for final curing for 16~20 hours.

[0017] A system for treating oily radioactive waste liquid includes the aforementioned oily radioactive waste liquid degreasing electrolytic cell.

[0018] The advantages of this invention compared to the prior art are: (1) This invention uses FRPP matrix layer as the main insulating carrier to directly achieve effective isolation from the power supply system; by overcoming the limitations of single material or chemical modification through the outer coating composite structure, a dual support structure of "FRPP matrix + modified reinforced high silica cloth" is constructed. With the chemical bonding of the transition layer, the overall pressure resistance is guaranteed to be ≥0.3MPa by means of the flexural modulus of FRPP matrix ≥2900MPa and the embedded reinforcement structure of high silica cloth; at the same time, while retaining the original insulation and pressure resistance performance of FRPP, a double flame retardant barrier is formed by physically coating high silica flame retardant cloth, which improves the flame retardant performance to UL94 V-2 level and above, avoids the problem of insufficient adhesion of the outer coating, effectively blocks the risk of hydrogen explosion from electrolysis, and overcomes the shortcomings of single FRPP flame retardancy.

[0019] (3) The surface of the FRPP substrate of the present invention is roughened by sandblasting / mechanical grinding, and chemical bonding is achieved by the modified transition layer of the same material and the silane interface bridging medium, which completely solves the problems of weak adhesion and easy cracking of traditional coatings; at the same time, the inner surface of the high silica cloth is treated with interface to enhance the bonding force with the adhesive, and the embedded reinforcement structure avoids the composite layer from delamination failure under cold and hot cycles and pressure fluctuations, ensuring long-term stable operation under harsh working conditions and extending the service life of the equipment.

[0020] (3) The present invention adopts a step-by-step process of “surface treatment - transition layer composite - adhesive coating - high silica cloth pretreatment - composite curing”, and ensures composite quality through stepped curing (pre-curing at 35~45℃ + final curing at 75~85℃) and pressure control (0.05~0.15MPa). The secondary adhesive coating design can be flexibly adapted to different working conditions. The whole adopts a non-metallic composite structure, which has no risk of metal corrosion and significantly reduces the total life cycle operating cost compared with stainless steel electrolytic cells.

[0021] (4) This invention is adapted to electrocatalytic oxidation deep oil removal technology, which reduces COD content through electrode reaction, with virtually no secondary waste, meeting the environmental protection requirements of the nuclear industry; the non-metallic structure has good radiation resistance, which can prevent the spread of radioactive materials and meet safety standards.

[0022] In summary, this invention, through the coordinated design of materials and structure, achieves a reliable structure and comprehensively improves the electrolytic cell in terms of insulation, pressure resistance (≥0.3MPa), and flame retardancy (UL94 V-2 level). It is suitable for oil-containing radioactive waste liquid treatment systems and provides a reliable and durable innovative equipment solution for deep oil removal of oil-containing radioactive waste liquid, possessing significant technological advancement and engineering application value. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the layered structure of the electrolytic cell of the present invention; Figure 2 This is a schematic cross-sectional view of the layered structure of the electrolytic cell of the present invention.

[0024] In the figure: 1 is the FRPP matrix layer, 2 is the modified FRPP transition layer, 3 is the flame-retardant adhesive layer, and 4 is the modified reinforced high-silica cloth layer. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Furthermore, unless otherwise specified, all reagents used below are conventional reagents in the art; and all experimental conditions and methods used, unless otherwise specified, are conventional conditions and methods in the art and will not be elaborated further.

[0026] Example 1 See Figures 1-2 An oil removal electrolytic cell for oily radioactive waste liquid in this embodiment includes, from the inside out, a FRPP matrix layer 1, a modified FRPP transition layer 2, a flame-retardant adhesive layer 3, and a modified reinforced high-silica cloth layer 4.

[0027] The FRPP matrix layer 1 provides structural support, insulation, and pressure resistance. It has a thickness of 5 mm and a flexural modulus ≥ 2900 MPa (GB / T 9341). The outer surface of the FRPP matrix layer 1 facing the modified FRPP transition layer 2 is treated to form a rough surface structure with a surface roughness Ra of 50 μm (GB / T 13288.1) to improve the bonding force with the transition layer.

[0028] The modified FRPP transition layer 2 is a composite layered structure with FRPP as the substrate, embedded with silane-based interfacial bridging medium and thermoplastic elastomer, and its thickness is 0.5 mm. Among them, the silane-based interfacial bridging medium is KH-550 type silane coupling agent, which enhances the reliability of interlayer connection through the compatibility characteristics of the same material and the interfacial bridging effect.

[0029] The flame-retardant adhesive layer 3 is a flame-retardant silicone-based adhesive layer, using Dow Corning® 732, with a thermal decomposition temperature ≥300℃ (ISO 11358), a flame retardant rating of UL94 V-2, and a total adhesive layer thickness of 2.0mm, which can form an effective flame-retardant barrier and buffer the difference in thermal expansion between layers.

[0030] The modified and reinforced high-silica fabric layer 4 is a composite reinforcement structure, comprising a high-silica fabric substrate and a glass fiber mesh embedded within the substrate, with a silane-based interface treatment layer disposed on the inner surface of the high-silica fabric substrate. The high-silica fabric substrate has a thickness of 2 mm and an oxygen index ≥45% (GB / T 5454); the silane-based interface treatment layer is a KH-570 type silane coupling agent coating layer with a coating thickness of 100 μm; the glass fiber mesh has a pore size of 3 mm and a mesh wire diameter of 0.8 mm. The embedded reinforcement structure enhances the impact resistance and pressure resistance of the outer layer.

[0031] Preparation method: (1) Surface treatment of substrate: The outer surface of the FRPP substrate with dimensions of 800×400×200mm is mechanically polished to form a rough surface, and then the surface dust is removed with compressed air; the FRPP substrate groove wall after treatment is the FRPP substrate layer 1 with a thickness of 5mm.

[0032] (2) Transition layer composite: FRPP granules are blended with 3wt% silane interfacial bridging medium and 5wt% thermoplastic elastomer, and hot-pressed into a modified FRPP transition layer 2 with a thickness of 0.5mm, which is then bonded to the outer surface of the FRPP matrix layer 1 after step (1).

[0033] (3) Adhesive coating: A flame-retardant silicone-based adhesive is uniformly coated on the outer surface of the modified FRPP transition layer 2 to form a flame-retardant adhesive layer 3 with a thickness of 1.5 mm; the coated substrate is placed in a room temperature ventilated environment to dry for 12 hours, and then a second layer of the same adhesive is coated, with a total adhesive layer thickness of 2.0 mm.

[0034] (4) Pretreatment of high silica cloth: Take a 2mm thick high silica cloth substrate (SiO2≥98%), immerse it in an ethanol solution of 5% silane coupling agent KH-570, take it out and dry it at 80℃ to form a 100μm thick interface treatment layer; then stack the glass fiber mesh cloth (pore size 3mm, mesh wire diameter 0.8mm) with the pretreated high silica cloth substrate, pre-impregnate it with flame retardant silicone adhesive, so that the adhesive fully fills the fiber gaps, and embed the mesh cloth into the high silica cloth substrate to obtain the modified reinforced high silica cloth layer 4.

[0035] (5) Composite curing: The modified and reinforced high silica cloth layer 4 is tightly wrapped around the outer surface of the flame retardant adhesive layer 3, and the air bubbles are removed by roller pressing. After removing the air bubbles, a pressure of 0.1 MPa is applied evenly, and an integrated electrolytic cell is formed by a stepped curing process (pre-curing at 40℃ for 6 hours, and then heating to 80℃ for final curing for 18 hours).

[0036] Example 2 See Figures 1-2 An oil removal electrolytic cell for oily radioactive waste liquid in this embodiment includes, from the inside out, a FRPP matrix layer 1, a modified FRPP transition layer 2, a flame-retardant adhesive layer 3, and a modified reinforced high-silica cloth layer 4.

[0037] The FRPP matrix layer 1 provides structural support, insulation, and pressure resistance. It has a thickness of 3 mm and a flexural modulus ≥ 2900 MPa (GB / T 9341). The outer surface of the FRPP matrix layer 1 facing the modified FRPP transition layer 2 is treated to form a rough surface structure with a surface roughness Ra of 40 μm (GB / T 13288.1) to improve the bonding force with the transition layer.

[0038] The modified FRPP transition layer 2 is a composite layered structure with FRPP as the substrate, embedded with silane-based interfacial bridging medium and thermoplastic elastomer, and its thickness is 0.3 mm. Among them, the silane-based interfacial bridging medium is KH-550 type silane coupling agent, which enhances the reliability of interlayer connection through the compatibility characteristics of the same material and the interfacial bridging effect.

[0039] The flame-retardant adhesive layer 3 is a flame-retardant silicone-based adhesive layer, using Dow Corning® 732, with a thermal decomposition temperature ≥300℃ (ISO 11358), a flame retardant rating of UL94 V-2, and a layer thickness controlled at 0.5mm, which can form an effective flame-retardant barrier and buffer the difference in thermal expansion between layers.

[0040] The modified and reinforced high-silica fabric layer 4 is a composite reinforcement structure, comprising a high-silica fabric substrate and a glass fiber mesh or honeycomb structure embedded within the substrate. The inner surface of the high-silica fabric substrate is provided with a silane-based interface treatment layer or a low-temperature plasma treatment layer. The high-silica fabric substrate has a thickness of 1 mm and an oxygen index ≥45% (GB / T5454). The silane-based interface treatment layer is a KH-570 type silane coupling agent coating layer with a coating thickness of 50 μm. The glass fiber mesh has a pore size of 2 mm and a mesh wire diameter of 0.5 mm. The embedded reinforcement structure enhances the impact resistance and pressure resistance of the outer layer.

[0041] Preparation method: (1) Surface treatment of substrate: The outer surface of the FRPP substrate with dimensions of 800×400×200mm is sandblasted and polished to form a rough surface. Then, the surface dust is removed by compressed air. The treated FRPP substrate groove wall is the FRPP substrate layer 1 with a thickness of 3mm.

[0042] (2) Transition layer composite: FRPP granules are blended with 1wt% silane interfacial bridging medium and 3wt% thermoplastic elastomer, and hot-pressed into a modified FRPP transition layer 2 with a thickness of 0.3mm, which is then bonded to the outer surface of the FRPP matrix layer 1 after step (1).

[0043] (3) Adhesive coating: A flame-retardant silicone-based adhesive is uniformly coated on the outer surface of the modified FRPP transition layer 2 to form a flame-retardant adhesive layer 3 with a thickness of 0.5 mm.

[0044] (4) Pretreatment of high silica cloth: Take a 1 mm thick high silica cloth substrate (SiO2≥98%), immerse it in an ethanol solution of 5% silane coupling agent KH-570, take it out and dry it at 80℃ to form a 50 μm thick interface treatment layer; then stack the glass fiber mesh cloth (pore size 2 mm, mesh wire diameter 0.5 mm) with the pretreated high silica cloth substrate, pre-impregnate it with flame retardant silicone adhesive, so that the adhesive fully fills the fiber gaps, and embed the mesh cloth into the high silica cloth substrate to obtain the modified reinforced high silica cloth layer 4.

[0045] (5) Composite curing: The modified and reinforced high-silica cloth layer 4 is tightly wrapped around the outer surface of the flame-retardant adhesive layer 3, and the air bubbles are removed by roller pressing. After removing the air bubbles, a pressure of 0.05MPa is applied evenly, and an integrated electrolytic cell is formed by a stepped curing process (pre-curing at 35℃ for 8 hours, and then heating to 75℃ for 20 hours).

[0046] Example 3 See Figures 1-2An oil removal electrolytic cell for oily radioactive waste liquid in this embodiment includes, from the inside out, a FRPP matrix layer 1, a modified FRPP transition layer 2, a flame-retardant adhesive layer 3, and a modified reinforced high-silica cloth layer 4.

[0047] The FRPP matrix layer 1 provides structural support, insulation, and pressure resistance. It has a thickness of 10 mm and a flexural modulus ≥ 2900 MPa (GB / T 9341). The outer surface of the FRPP matrix layer 1 facing the modified FRPP transition layer 2 is treated to form a rough surface structure with a surface roughness Ra of 60 μm (GB / T 13288.1) to improve the bonding force with the transition layer.

[0048] The modified FRPP transition layer 2 is a composite layered structure with FRPP as the substrate, embedded with silane-based interfacial bridging medium and thermoplastic elastomer, and its thickness is 1.0 mm. Among them, the silane-based interfacial bridging medium is KH-550 type silane coupling agent, which enhances the reliability of interlayer connection through the compatibility characteristics of the same material and the interfacial bridging effect.

[0049] The flame-retardant adhesive layer 3 is a flame-retardant silicone-based adhesive layer, using Dow Corning® 732, with a thermal decomposition temperature ≥300℃ (ISO 11358), a flame retardant rating of UL94 V-2, and a total adhesive layer thickness of 1.0mm, which can form an effective flame-retardant barrier and buffer the difference in thermal expansion between layers.

[0050] The modified and reinforced high-silica fabric layer 4 is a composite reinforcement structure, comprising a high-silica fabric substrate and a glass fiber mesh or honeycomb structure embedded within the substrate. The inner surface of the high-silica fabric substrate is provided with a silane-based interface treatment layer or a low-temperature plasma treatment layer. The high-silica fabric substrate has a thickness of 4 mm and an oxygen index ≥45% (GB / T 5454). The silane-based interface treatment layer is a KH-570 type silane coupling agent coating layer with a coating thickness of 200 μm. The glass fiber mesh has a pore size of 5 mm and a mesh wire diameter of 1.2 mm. The embedded reinforcement structure enhances the impact resistance and pressure resistance of the outer layer.

[0051] Preparation method: (1) Surface treatment of substrate: The outer surface of the FRPP substrate with dimensions of 800×400×200mm is mechanically polished to form a rough surface, and then the surface dust is removed with compressed air; the FRPP substrate groove wall after treatment is the FRPP substrate layer 1 with a thickness of 10mm.

[0052] (2) Transition layer composite: FRPP granules are blended with 5wt% silane interfacial bridging medium and 8wt% thermoplastic elastomer, and hot-pressed into a modified FRPP transition layer 2 with a thickness of 1.0mm, which is then bonded to the outer surface of the FRPP matrix layer 1 after step (1).

[0053] (3) Adhesive coating: A flame-retardant silicone-based adhesive is uniformly coated on the outer surface of the modified FRPP transition layer 2 to form a flame-retardant adhesive layer 3 with a thickness of 0.5 mm; the coated substrate is placed in a room temperature ventilated environment to dry for 12 hours, and then a second layer of the same adhesive is coated, with a total adhesive layer thickness of 1.0 mm.

[0054] (4) Pretreatment of high silica cloth: Take a 4mm thick high silica cloth substrate (SiO2≥98%), immerse it in an ethanol solution of 5% silane coupling agent KH-570, take it out and dry it at 80℃ to form an interface treatment layer of 50~200μm thickness; then stack the glass fiber mesh cloth (pore size of 5mm, mesh wire diameter of 1.2mm) with the pretreated high silica cloth substrate, pre-impregnate it with flame retardant silicone adhesive, so that the adhesive fully fills the fiber gaps, and embed the mesh cloth into the high silica cloth substrate to obtain the modified reinforced high silica cloth layer 4.

[0055] (5) Composite curing: The modified and reinforced high-silica cloth layer 4 is tightly wrapped around the outer surface of the flame-retardant adhesive layer 3, and the air bubbles are removed by roller pressing. After removing the air bubbles, a pressure of 0.15MPa is applied evenly, and an integrated electrolytic cell is formed by a stepped curing process (pre-curing at 45℃ for 4 hours, and then heating to 85℃ for final curing for 16 hours).

[0056] Example 4 See Figures 1-2 The oil removal electrolytic cell for oily radioactive waste liquid in this embodiment is basically the same as that in embodiment 1, except that the modified and reinforced high-silica cloth layer 4 structure is a honeycomb structure embedded inside the high-silica cloth substrate; the pore size of the honeycomb structure is 5mm and the wall thickness is 0.5mm.

[0057] Accordingly, the pretreatment steps for high-silica cloth are adjusted as follows: A 2mm thick high-silica fabric substrate (SiO2≥98%) was immersed in an ethanol solution of 5% silane coupling agent KH-570, and then dried at 80℃ to form a 100μm thick interface treatment layer. A honeycomb structure (5mm pore size, 0.5mm wall thickness) was then laminated with the pretreated high-silica fabric substrate. A flame-retardant silicone-based adhesive was used for pre-impregnation to ensure that the adhesive fully filled the fiber gaps and honeycomb pores, thus embedding the honeycomb structure into the high-silica fabric substrate to obtain the modified and reinforced high-silica fabric layer 4.

[0058] Example 5 See Figures 1-2The oil removal electrolytic cell for oily radioactive waste liquid in this embodiment is basically the same as that in embodiment 1, except that: in the modified and reinforced high silica cloth layer structure 4, a low-temperature plasma treatment layer is provided on the inner surface of the high silica cloth substrate.

[0059] Accordingly, the pretreatment steps for high-silica cloth are adjusted as follows: A 2mm thick high-silica cloth substrate (SiO2≥98%) was subjected to low-temperature plasma treatment on its inner surface (plasma power 150W, treatment time 3min, vacuum degree 50Pa) to form a corresponding treatment layer; then, a glass fiber mesh (pore size 3mm, mesh wire diameter 0.8mm) was laminated with the pretreated high-silica cloth substrate, and a flame-retardant silicone-based adhesive was used for pre-impregnation to ensure that the adhesive fully filled the fiber gaps, thus embedding the mesh into the high-silica cloth substrate to obtain the modified and reinforced high-silica cloth layer 4.

[0060] Example 6 This embodiment provides an oil-containing radioactive waste liquid treatment system, which includes the electrolytic cell prepared in the above embodiment.

[0061] Comparative Example 1 The electrolytic cell in this comparative example is basically the same as that in Example 1, except that the modified FRPP transition layer 2 is removed and the flame-retardant adhesive layer 3 is directly coated on the outer surface of the FRPP substrate layer 1.

[0062] Comparative Example 2 The electrolytic cell in this comparative example is basically the same as that in Example 1, except that the high-silica cloth substrate is not treated with KH-570 silane and does not have embedded glass fiber mesh cloth. Instead, pure high-silica cloth is used directly as the outer layer.

[0063] Comparative Example 3 The electrolytic cell in this comparative example is basically the same as that in Example 1, except that it uses only a 5mm thick FRPP substrate as the electrolytic cell and has no transition layer, adhesive layer, or high-silica cloth layer.

[0064] Experimental Example This experimental example is used to test the core performance of the electrolytic cells of the present invention and Comparative Examples 1-3.

[0065] Electrolytic cells of the present invention (Example 1) and comparative examples 1-3 were prepared respectively. Performance tests were carried out according to the following test items, test standards and test methods to compare and verify the superiority of the electrolytic cells of the present invention. The specific contents are as follows: I. Test Items, Standards and Methods 1. Flame retardancy test Standard based on: ANSI / UL 94-2015; Technical specifications: UL94 V-2 level; Test method: A combustion test was conducted on each electrolytic cell. The sample was subjected to an open flame at 700℃ for 60 seconds, and the self-extinguishing time was recorded to verify whether it met the technical requirement of self-extinguishing time ≤ 5 seconds.

[0066] 2. Pressure resistance test Standard based on: GB / T 6111-2018; Technical specifications: 0.45MPa pressure holding for 30 minutes; Test method: Fill each electrolytic cell with clean water, gradually increase the pressure to 0.45MPa using a pressurizing device, maintain the pressure for 30 minutes, and observe whether the cell shows signs of leakage, plastic deformation, or other phenomena.

[0067] 3. Adhesion test Standard based on: ASTM D4541-17; Technical specifications: Peel strength ≥ 2.5 MPa; Test method: Samples were taken at the interface of the composite layer in each electrolytic cell and a pull-out test was performed using a pull-out tester. After the test, the interface was observed to see if it delaminated or peeled off, and the peel strength value was recorded to verify whether the technical specifications were met.

[0068] 4. Thermal stability test Standard based on: GB / T 7141-2008; Technical specifications: -40℃ to 120℃, 50 cycles of hot and cold cycling; Test method: Place each electrolytic cell sample in a high and low temperature test chamber and conduct a cold and hot cycle test from -40℃ (holding temperature for 2 hours) to 120℃ (holding temperature for 2 hours). After a total of 50 cycles, observe whether the composite structure shows cracking, delamination, bulging or other phenomena.

[0069] II. Test Results The results are shown in Table 1.

[0070] Table 1 Core performance test results

[0071] The results above show that the electrolytic cell of this invention fully meets all the specified technical indicators. Through the four-layer composite structure design, it achieves a synergistic improvement in flame retardancy, pressure resistance, adhesion, and thermal stability. Meanwhile, Comparative Example 1 verifies the key role of the transition layer in adhesion and thermal stability. Although the flame retardancy and basic pressure resistance can be met without it, the interlayer bonding force is greatly reduced, and it is prone to cracking after thermal cycling, making long-term stable operation impossible. Comparative Example 2 proves that silane interface treatment and embedded reinforcement structure are the core technical features to ensure adhesion and thermal stability. Without them, the adhesion of the outer layer structure decreases, and the thermal stability decreases, failing to meet the technical requirements. Comparative Example 3 shows that the flame retardancy performance of a single FRPP material cannot meet the technical requirements.

[0072] In summary, this invention, through the synergistic design of materials and structure, achieves a comprehensive improvement in the electrolytic cell's insulation, pressure resistance (≥0.3MPa), and flame retardancy (UL94 V-2 level). It is suitable for oil-containing radioactive waste liquid treatment systems, providing a reliable and durable innovative equipment solution for deep oil removal from oil-containing radioactive waste liquid, and possesses significant technological advancement and engineering application value.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolytic cell for removing oil from radioactive waste liquid containing oil, characterized in that, The material comprises, from the inside out, a FRPP matrix layer, a modified FRPP transition layer, a flame-retardant adhesive layer, and a modified reinforced high-silica fabric layer. The modified FRPP transition layer is a composite layered structure with FRPP as the substrate, embedded with a silane-based interfacial bridging medium and a thermoplastic elastomer. The flame-retardant adhesive layer is a flame-retardant silicone-based adhesive layer. The modified reinforced high-silica fabric layer is a composite reinforcement structure, comprising a high-silica fabric substrate and a glass fiber mesh or honeycomb structure embedded within the substrate. The inner surface of the high-silica fabric substrate is provided with a silane-based interfacial treatment layer or a low-temperature plasma treatment layer.

2. The electrolytic cell according to claim 1, characterized in that, The thickness of the FRPP matrix layer is 3~10mm, and its flexural modulus is ≥2900MPa.

3. The electrolytic cell according to claim 1, characterized in that, The thickness of the modified FRPP transition layer is 0.3~1.0 mm; and the silane-based interfacial bridging medium is KH-550 type silane coupling agent, which accounts for 1~5% of the mass of the modified FRPP transition layer; the thermoplastic elastomer is EVA elastomer, which accounts for 3~8% of the mass.

4. The electrolytic cell according to claim 1, characterized in that, The flame-retardant silicone-based adhesive layer has a thermal decomposition temperature ≥300℃, a flame retardancy rating of UL94 V-2, and a layer thickness of 0.5~2.0mm.

5. The electrolytic cell according to claim 1, characterized in that, In the modified and reinforced high-silica cloth layer: The thickness of the high-silica cloth substrate is 1~4mm, and the oxygen index is ≥45%; The silane-based interface treatment layer is a KH-570 type silane coupling agent coating layer with a thickness of 50~200μm; The pore size of the fiberglass mesh is 2~5mm, and the wire diameter is 0.5~1.2mm; The honeycomb structure has a pore size of 3~8mm and a wall thickness of 0.3~0.8mm.

6. The electrolytic cell according to claim 1, characterized in that, The outer surface of the FRPP matrix layer facing the modified FRPP transition layer is also provided with a rough surface structure, which is formed by sandblasting or mechanical grinding, and its surface roughness Ra is 40~60μm.

7. A method for preparing an electrolytic cell as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Surface treatment of the substrate: The outer surface of the FRPP substrate layer is sandblasted or mechanically polished to form a rough surface, and then the surface dust is removed with compressed air; (2) Transition layer composite: FRPP, silane-based interfacial bridging medium and thermoplastic elastomer are blended and hot-pressed into a modified FRPP transition layer, which is then bonded to the outer surface of the FRPP matrix layer after step (1). (3) Adhesive coating: A flame-retardant silicone-based adhesive is uniformly coated on the outer surface of the modified FRPP transition layer to form a flame-retardant adhesive layer; (4) Pretreatment of high silica cloth: The inner surface of the high silica cloth substrate is treated with silane interface treatment or low temperature plasma treatment to form a treatment layer. Then, glass fiber mesh or honeycomb structure is embedded in the high silica cloth substrate to obtain a modified and reinforced high silica cloth layer. (5) Composite curing: The modified and reinforced high silica cloth layer obtained in step (4) is coated on the outer surface of the flame retardant adhesive layer. After removing air bubbles, pressure is applied, and an integrated electrolytic cell is formed through a step curing process.

8. The preparation method according to claim 7, characterized in that, In step (3), the coating thickness of the flame-retardant silicone adhesive is 0.5~1.5mm. If a second coating is required, the second coating should be carried out after drying in a ventilated environment at room temperature for 12~24 hours. The total adhesive layer thickness should not exceed 2.0mm.

9. The preparation method according to claim 7, characterized in that, In step (5), the pressure applied is 0.05~0.15MPa, and the step curing process is: pre-curing at 35~45℃ for 4~8 hours, and then heating up to 75~85℃ for final curing for 16~20 hours.

10. A system for treating oil-containing radioactive waste liquid, characterized in that, The oil removal electrolytic cell for oily radioactive waste liquid as described in any one of claims 1 to 6.

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