A method for preparing a nickel-ethylenediamine complex extract based on nickel plating waste and its application in forward osmosis treatment of nickel-containing wastewater.

Abstract

This invention provides a nickel-ethylenediamine complex-based draw solution derived from nickel plating waste, its preparation method, and its application in forward osmosis treatment of nickel-containing wastewater, relating to the field of forward osmosis water treatment. The preparation method of the nickel-ethylenediamine complex-based draw solution derived from nickel plating waste includes the following steps: preparing a nickel-ethylenediamine complex and preparing the draw solution. The nickel-ethylenediamine complex-based draw solution of this invention can effectively adapt to the characteristics of nickel-containing wastewater of different concentrations under the premise of high water flux and low solute loss, achieving efficient and stable treatment of nickel-containing wastewater and facilitating nickel recovery; simultaneously, after forward osmosis, the recovery operation of the forward osmosis draw solution is simple, has a high recovery rate, good repeatability, and can be recycled for a long time.

Description

Technical Field

[0001] This invention relates to the field of forward osmosis water treatment, and in particular to a nickel-ethylenediamine complex extractant derived from nickel plating waste, its preparation method, and its application in forward osmosis treatment of nickel-containing wastewater. Background Technology

[0002] Existing nickel plating wastewater, except for free Ni 2+ In addition, there are stable complexes formed by nickel with organic acids, amino acids, or amine compounds. Among them, the nickel-ethylenediamine complex is structurally stable and highly water-soluble, making it difficult to remove by traditional methods such as chemical precipitation. Existing treatment methods mostly use advanced oxidation to destroy organic ligands and release Ni². + It can be recycled later, but its processing is complex, energy-intensive, and costly.

[0003] Forward osmosis water treatment technology, driven by osmotic pressure difference and requiring no external pressure, offers advantages such as low membrane fouling and high selectivity. In a forward osmosis system, the draw solution is crucial for providing the osmotic driving force, and its performance determines the system's mass transfer efficiency. Currently, commonly used small-molecule inorganic salt draw solutions (such as NaCl and NH4HCO3) in forward osmosis processes, while possessing high osmotic pressure and readily available, suffer from severe back diffusion, significant solute loss, and high energy consumption during recovery. While macromolecular polyelectrolytes exhibit low back diffusion, their high viscosity and low water flux, coupled with reliance on pressure-driven nanofiltration for recovery, result in high energy consumption and membrane fouling. Furthermore, environmentally responsive draw solutions reported in recent years, such as ionic liquids, hydrogels, and nanocomposites, while capable of recovery through external field control, generally suffer from complex synthesis and low water flux.

[0004] In forward osmosis treatment of nickel-containing wastewater, existing forward osmosis draw media cannot overcome the shortcomings of low water flux, severe solute loss, and difficult recovery, while simultaneously achieving efficient and stable treatment of nickel-containing wastewater of varying concentrations, nor can they effectively recover nickel from the wastewater. Therefore, this paper proposes a forward osmosis draw solution that, while offering high water flux, low solute loss, high recovery rate, and simple regeneration operation, is effectively adaptable to the characteristics of nickel-containing wastewater of different concentrations, achieving efficient and stable treatment of nickel-containing wastewater and effectively recovering nickel from the wastewater. This has significant technical importance and research value. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a nickel-ethylenediamine complex-based extractant derived from nickel plating waste. This extractant is applied to nickel-containing wastewater treatment and nickel recovery. Leveraging the high ionization degree of the nickel-ethylenediamine complex in water and its ability to form a stable octahedral configuration and three-dimensional hydrogen bond network, it effectively suppresses reverse diffusion and enhances the osmosis driving force. It can effectively adapt to the characteristics of nickel-containing wastewater of different concentrations under the premise of high water flux and low solute loss, achieving efficient and stable treatment of nickel-containing wastewater and facilitating nickel recovery. Furthermore, after forward osmosis, the recovery operation of the forward osmosis extractant is simple, has a high recovery rate, good repeatability, and can be reused for a long time.

[0006] The present invention also provides a method for preparing the extracting solution based on nickel-ethylenediamine complex derived from nickel plating waste.

[0007] The present invention also provides the application of the nickel-ethylenediamine complex extract based on nickel plating waste in the forward osmosis treatment of nickel-containing wastewater.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a nickel-ethylenediamine complex-based extracting solution derived from nickel plating waste includes the following steps: preparing the nickel-ethylenediamine complex and preparing the extracting solution; The method for preparing nickel-ethylenediamine complexes is as follows: ethylenediamine is added dropwise to an aqueous solution of nickel ions. After the addition is complete, the mixture is kept at a temperature of 40-45°C to obtain a reaction solution. An organic solvent is added to the reaction solution to precipitate the mixture. The solid is then separated and collected. The solid is washed and dried to obtain the nickel-ethylenediamine complex. The method for preparing the draw solution is to mix a nickel-ethylenediamine complex with deionized water to obtain a nickel-ethylenediamine complex draw solution with a nickel-ethylenediamine complex concentration of 0.1-2 mol / L, which is derived from nickel plating waste.

[0009] Preferably, in the preparation of the nickel-ethylenediamine complex, the molar ratio of nickel ions to ethylenediamine is 1:1 or 1:3.5-4.

[0010] Preferably, in the preparation of the nickel-ethylenediamine complex, the ethylenediamine is added over a period of 2-3 minutes. After the ethylenediamine is added, the reaction is kept at 40-45℃ for 3-5 hours.

[0011] Preferably, in the preparation of the nickel-ethylenediamine complex, the nickel ion concentration in the nickel ion aqueous solution is 4.8-5.2 mol / L.

[0012] Preferably, in the preparation of the nickel-ethylenediamine complex, the nickel ions in the nickel ion aqueous solution are provided by nickel nitrate.

[0013] Preferably, in the preparation of the nickel-ethylenediamine complex, the organic solvent used for precipitation is acetone or ethanol.

[0014] A nickel-ethylenediamine complex extracting solution derived from nickel plating waste was prepared using the aforementioned preparation method.

[0015] An application of the aforementioned nickel-ethylenediamine complex extractant derived from nickel plating waste, wherein the nickel-ethylenediamine complex extractant derived from nickel plating waste is used to treat nickel-containing wastewater by forward osmosis.

[0016] Preferably, the nickel ion content in the nickel-containing wastewater is 0-2000 ppm.

[0017] Furthermore, the application of the nickel-ethylenediamine complex extract also includes the following steps: recovery and regeneration treatment; The method for recycling and regeneration is as follows: after the forward osmosis treatment of nickel-containing wastewater is completed, an organic solvent is added to the draw solution of the nickel-ethylenediamine complex to be treated for precipitation, and the solids are separated and collected. The solids are washed and dried to recover the nickel-ethylenediamine complex. Then, the nickel-ethylenediamine complex is mixed with deionized water to prepare a new draw solution of nickel-ethylenediamine complex with a concentration of 0.1-2 mol / L, which is then used again for forward osmosis treatment of nickel-containing wastewater.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The nickel-ethylenediamine complex draw solution of this invention is designed for the characteristics of nickel-containing wastewater and its properties during forward osmosis. Utilizing the high ionization degree of nickel-ethylenediamine complexes in water, their ability to form stable octahedral configurations and three-dimensional hydrogen bond networks, and their capacity to suppress back diffusion and enhance osmotic driving force, this solution is used as a draw solution for forward osmosis treatment of nickel-containing wastewater. It effectively adapts to the characteristics of nickel-containing wastewater of varying concentrations while maintaining high water flux and low solute loss, achieving efficient and stable treatment of nickel-containing wastewater and facilitating nickel recovery. Furthermore, after forward osmosis, the recovery of the forward osmosis extract from the draw solution is simple, has a high recovery rate, good repeatability, and can be reused for a long period. Specifically: (1) The present invention uses the nickel-ethylenediamine complex as the positive osmotic absorbent because of its good solubility and high charge in water, and has high osmotic pressure. Under the condition that the membrane active layer faces the absorbent or the membrane active layer faces the feed liquid, the water flux generated by the nickel-ethylenediamine absorbent is much higher than that generated by the NaCl absorbent solution of the same concentration.

[0019] (2) In this invention, the nickel-ethylenediamine complex is used as the positive osmosis extractant. Because Ni in the system... 2+The octahedral coordination configuration at the center and the amino groups on the ethylenediamine form a three-dimensional hydrogen bond network with the surrounding water molecules and nitrate ions, which significantly increases the solute particle size, making it difficult for the solute to pass through the forward osmosis membrane and effectively solving the problem of severe solute loss.

[0020] (3) The present invention uses the nickel-ethylenediamine complex as the positive osmosis extractant. After the positive osmosis treatment is completed, the diluted extractant can be recovered by simple organic solvent displacement to obtain solid precipitate, thereby realizing the regeneration of the extractant. The recovery process is mild, easy to operate, stable, has a high recovery rate and good repeatability, which is conducive to the long-term recycling of the extractant. It effectively realizes the regeneration and recycling of the nickel-ethylenediamine complex and its extractant at room temperature and pressure.

[0021] (4) The present invention uses the nickel-ethylenediamine complex as the forward osmosis extractant for the forward osmosis treatment of nickel-containing wastewater. It can achieve high throughput and good stability for nickel-containing wastewater with different nickel concentrations and different anion compositions, demonstrating its application potential in the resource utilization treatment of nickel plating wastewater. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the synthesis mechanism of nickel-ethylenediamine complexes according to embodiments of the present invention.

[0023] Figure 2 This is a graph showing the forward osmosis flux test results when the membrane active layer faces the feed liquid condition in Example 2.

[0024] Figure 3 This is a graph showing the forward osmosis flux test results when the membrane active layer faces the draw solution in Example 2.

[0025] Figure 4 This is a graph showing the test results of forward osmosis and reverse solute loss when the membrane active layer faces the feed liquid in Example 2.

[0026] Figure 5 This is a graph showing the test results of forward osmosis and reverse solute loss when the membrane active layer faces the draw solution in Example 2.

[0027] Figure 6 In Example 3, when the active membrane layer faces the feed solution, 1 mol / L Ni-en, NaCl, and NH4HCO3 were used as the extraction solutions, and different Ni concentrations of 50 ppm, 500 ppm, 1000 ppm, and 2000 ppm were used. 2+ The graph shows the test results of a forward osmosis test conducted on the feed solution for 30 minutes.

[0028] Figure 7In Example 3, when the active membrane layer faces the feed solution, 1 mol / L Ni-en, NaCl, and NH4HCO3 were used as the extraction solutions, and 1000 ppm Ni was used as the extraction solution. 2+ The graph shows the test results of a forward osmosis test conducted on the feed solution for 36 hours. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] This invention provides a method for preparing a nickel-ethylenediamine complex extracting solution derived from nickel plating waste, comprising the following steps: preparing a nickel-ethylenediamine complex and preparing an extracting solution.

[0032] In the preparation of nickel-ethylenediamine complexes, the nickel-ethylenediamine complexes are nickel-monoethylenediamine complexes (Ni-en) or nickel-triethylenediamine complexes (Ni-3en); the preparation reaction mechanism is as follows: Figure 1 As shown.

[0033] The preparation method of the nickel-ethylenediamine complex is as follows: nickel nitrate hexahydrate is dissolved in deionized water, and an equimolar amount of ethylenediamine is added dropwise under stirring. The solution color rapidly changes from green to blue, indicating that Ni... 2+ The reaction with ethylenediamine occurs; after the addition is complete, the mixture is refluxed and stirred at 40-45℃ for 3-5 hours to obtain the reaction solution; acetone is added to the reaction solution to precipitate the mixture, the solid is collected by filtration, the solid is washed with acetone and dried under vacuum to obtain the nickel-ethylenediamine complex.

[0034] Preferably, the nickel-monoethylenediamine complex is prepared using a concentrated solution of nickel nitrate hexahydrate, wherein nickel nitrate hexahydrate is dissolved in an aqueous solution formed by deionized water, and the nickel ion concentration is 4.8-5.2 mol / L.

[0035] Preferably, in the preparation of the nickel-ethylenediamine complex, the ethylenediamine is added over a period of 2-3 minutes.

[0036] The preparation method of the nickel-triethylenediamine complex is as follows: nickel nitrate hexahydrate is dissolved in deionized water, and ethylenediamine, with a molar amount of nickel nitrate hexahydrate, is slowly added dropwise under stirring. The solution color quickly turns purple. After the addition is complete, the mixture is refluxed and stirred at 40-45℃ for 3-5 hours to obtain a reaction solution. Ethanol is added to the reaction solution to precipitate the mixture. The solid is collected by filtration, washed with ethanol, and then dried under vacuum to obtain the nickel-triethylenediamine complex.

[0037] Preferably, the nickel-triethylenediamine complex is prepared using a concentrated solution of nickel nitrate hexahydrate, wherein nickel nitrate hexahydrate is dissolved in an aqueous solution formed by deionized water, and the nickel ion concentration is 4.8-5.2 mol / L.

[0038] Preferably, in the preparation of the nickel-ethylenediamine complex, the ethylenediamine is added over a period of 2-3 minutes.

[0039] The method for preparing the draw solution is to mix the nickel-ethylenediamine complex with deionized water to obtain a nickel-ethylenediamine complex draw solution with a nickel-ethylenediamine complex concentration of 0.1-2 mol / L, which is derived from nickel plating waste.

[0040] Preferably, when the nickel-ethylenediamine complex is a nickel-monoethylenediamine complex, the concentration of the nickel-monoethylenediamine complex in the forward osmosis draw solution is 0.1-2 mol / L; more preferably, the concentration of the nickel-monoethylenediamine complex in the forward osmosis draw solution is one of the following: 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, or 2 mol / L.

[0041] Preferably, when the nickel-ethylenediamine complex is a nickel-triethylenediamine complex, the concentration of the nickel-triethylenediamine complex in the forward osmosis draw solution is 0.1-1.5 mol / L; more preferably, the concentration of the nickel-triethylenediamine complex in the forward osmosis draw solution is one of the following: 0.1 mol / L, 0.5 mol / L, 1 mol / L, or 1.5 mol / L.

[0042] The present invention also provides an extracting solution based on nickel-ethylenediamine complexes derived from nickel plating waste, prepared by the aforementioned method.

[0043] This invention also provides the application of the nickel-ethylenediamine complex extractant derived from nickel plating waste in the forward osmosis treatment of nickel-containing wastewater, wherein the nickel-containing wastewater is treated by forward osmosis using the nickel-ethylenediamine complex extractant derived from nickel plating waste.

[0044] Furthermore, in the forward osmosis treatment of nickel-containing wastewater using a nickel-ethylenediamine complex extract derived from nickel plating waste, the forward osmosis membrane used is a carboxylated polyamide forward osmosis membrane, which is prepared by the following steps: preparing a polyethersulfone ultrafiltration membrane, preparing a polyamide forward osmosis membrane, and controlling hydrolysis modification. The method for preparing polyethersulfone ultrafiltration membrane is as follows: polyethersulfone, polyethylene glycol, N-methyl-2-pyrrolidone, and deionized water are mixed and polymerized by heating to obtain a casting solution; the casting solution is coated onto a flat plate and a polyethersulfone ultrafiltration membrane with a thickness of 100-120 μm is obtained by phase inversion. The method for preparing the polyamide forward osmosis membrane is as follows: an interfacial polymerization reaction is carried out on a polyethersulfone ultrafiltration membrane using an aqueous monomer m-phenylenediamine solution and an oil-phase monomer pyromellitic acid chloride solution to obtain the polyamide forward osmosis membrane. The method of controllable hydrolysis modification is to completely immerse the polyamide forward osmosis membrane in the mixed modification solution, soak it at room temperature and then take it out to obtain the carboxylated polyamide forward osmosis membrane. The mixed modified solution is a mixed solution of sulfuric acid, ethanol and deionized water.

[0045] Preferably, in the preparation of the polyethersulfone ultrafiltration membrane, the weight ratio of polyethersulfone, polyethylene glycol 400, and N-methyl-2-pyrrolidone is 15%:42.5%:42.5%.

[0046] Preferably, in the preparation of the polyethersulfone ultrafiltration membrane, the heating polymerization temperature is 60-70℃ and the polymerization time is 12-16h.

[0047] Preferably, in the preparation of the polyamide forward osmosis membrane, the concentration of the aqueous phase monomer m-phenylenediamine solution is 2 wt%; and the concentration of the oil phase monomer trimesoyl chloride solution is 0.15 wt%.

[0048] Preferably, in the controlled hydrolysis modification, the soaking time at room temperature is 10-30 minutes; The mixed modified solution contains 1 mol / L sulfuric acid, 70% ethanol by volume, and the remainder is deionized water.

[0049] The application of nickel-ethylenediamine complex extract based on nickel plating waste in forward osmosis treatment of nickel-containing wastewater also includes the following steps: recovery and regeneration treatment; The method for recycling and regeneration is as follows: an organic solvent is added to the forward osmosis draw solution to be treated for precipitation, the solids are collected by filtration, the solids are washed with ethanol and then vacuum dried to recover nickel-ethylenediamine complexes; then the nickel-ethylenediamine complexes are mixed with deionized water to reconstitute the nickel-ethylenediamine complex draw solution based on nickel plating waste, and then used again for forward osmosis treatment of nickel-containing wastewater.

[0050] Preferably, in the recycling and regeneration process, the organic solvent is acetone or ethanol.

[0051] The present invention will be further described below with reference to some specific embodiments.

[0052] Example 1 This embodiment provides a method for preparing a nickel-ethylenediamine complex extracting solution derived from nickel plating waste, specifically as follows: 1. Preparation of nickel-ethylenediamine complexes (1) Preparation of nickel-ethylenediamine complex Ni-en Nickel nitrate hexahydrate (50 mmol, 14.6 g) was dissolved in 10 mL of deionized water. Ethylenediamine (50 mmol, 3.0 g), in an equal molar amount to nickel nitrate hexahydrate, was slowly added dropwise with stirring. The solution color rapidly changed from green to blue. After the addition was complete, the reaction system was refluxed and stirred at 40 °C for 3 h to obtain the reaction solution. Acetone was added to the reaction solution to precipitate the product. The solid was collected by filtration, washed with acetone, and dried under vacuum to obtain pure nickel-monoethylenediamine complex (Ni-en) with a yield (based on nickel ions) of 78%.

[0053] (2) Preparation of nickel-triethylenediamine complex Ni-3en Nickel nitrate hexahydrate (50 mmol, 14.6 g) was dissolved in 10 mL of deionized water. Under stirring, ethylenediamine (200 mmol, 12.0 g) of 4 times the molar amount of nickel nitrate hexahydrate was slowly added dropwise, and the solution color quickly turned purple. After the addition was complete, the reaction system was refluxed and stirred at 40 °C for 3 h to obtain the reaction solution. Ethanol was added to the reaction solution to precipitate the product. The solid was collected by filtration, washed with ethanol, and dried under vacuum to obtain pure nickel-triethylenediamine complex (Ni-3en) with a yield (based on nickel ions) of 80%.

[0054] 2. Preparation of the extraction solution The nickel-monoethylenediamine complex was mixed evenly with deionized water to prepare extracts with concentrations of 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, and 2 mol / L, respectively, to obtain gradient concentrations of nickel-monoethylenediamine complex extracts derived from nickel plating waste.

[0055] The nickel-triethylenediamine complex was mixed with deionized water to prepare extracts with concentrations of 0.1 mol / L, 0.5 mol / L, 1 mol / L, and 1.5 mol / L, respectively, to obtain gradient concentration extracts based on nickel-triethylenediamine complex derived from nickel plating waste.

[0056] This embodiment also provides the aforementioned nickel-monoethylenediamine complex extracting solution and nickel-triethylenediamine complex extracting solution with gradient concentrations derived from nickel plating waste.

[0057] This embodiment also provides the application of the aforementioned nickel-ethylenediamine complex draw solution derived from nickel plating waste, using the nickel-ethylenediamine complex draw solution derived from nickel plating waste to treat nickel-containing wastewater via forward osmosis. Simultaneously, after the forward osmosis treatment is completed, recovery and regeneration are performed: acetone is added to the forward osmosis draw solution to induce precipitation, the solids are collected by filtration, the solids are washed with ethanol, vacuum dried, and the nickel-ethylenediamine complex is recovered; then the nickel-ethylenediamine complex is mixed with deionized water to reconstitute the nickel-ethylenediamine complex draw solution derived from nickel plating waste, which is then used again for forward osmosis treatment of nickel-containing wastewater.

[0058] Example 2 Forward osmosis performance tests were conducted using the nickel-ethylenediamine complex draw solution from Example 1. The draw performance of the draw solution from Example 1 was evaluated using a laboratory-scale forward osmosis system.

[0059] Specifically, deionized water with a resistivity of 18.25 MΩ·cm was used as the feed solution, and Ni-en, Ni-3en, NaCl, and NH4HCO3 solutions with concentrations of 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, and 2 mol / L were used as draw solutions, respectively; a flat sheet membrane (PA-M0) or a modified membrane (PA-M1) was used for the forward osmosis; the forward osmosis membrane area was 4.5 cm². 2 Under 25℃ conditions, a membrane orientation comparison test was conducted with the membrane active layer facing the feed liquid (forward osmosis FO mode) and the membrane active layer facing the draw liquid (pressure damped osmosis PRO mode). The test process lasted for 30 minutes, and three brand-new membranes were used to repeat the test three times under the same conditions, and the average value was taken.

[0060] In the above experiments, both the flat sheet membrane (PA-M0) and the modified membrane (PA-M1) were self-made composite membranes. The preparation method of the flat sheet membrane (PA-M0) was as follows: first, a porous polyethersulfone ultrafiltration membrane was prepared by phase inversion; then, a polyamide separation layer was formed on the surface of the polyethersulfone support layer substrate membrane through interfacial polymerization to obtain the flat sheet membrane (PA-M0); the preparation of the modified membrane (PA-M1) was based on the flat sheet membrane (PA-M0), which was placed in a sulfuric acid-ethanol-water mixed solution for controlled hydrolysis modification to form a solvent-controlled carboxylation layer, thus obtaining the modified membrane (PA-M1).

[0061] The specific preparation steps for the flat sheet membrane (PA-M0) and the modified membrane (PA-M1) are as follows: 1. Preparation of polyethersulfone ultrafiltration membrane Polyethersulfone (15 wt%), polyethylene glycol 400 (42.5 wt%), and N-methyl-2-pyrrolidone (42.5 wt%) were mixed evenly in a three-necked flask and reacted with stirring in a constant temperature water bath at 70°C for 12 hours to prepare a casting solution via thermal polymerization. After the casting solution cooled naturally to room temperature, it was allowed to stand for 24 hours to obtain the casting solution for preparing the support layer. Using a clean glass plate, an appropriate amount of casting solution was poured onto the glass plate and scraped off at a uniform speed from above the glass plate with a spatula to form a transparent casting solution film. The glass plate with the casting solution film was then completely immersed in deionized water. Under water bath conditions, after phase inversion, a polyethersulfone ultrafiltration membrane with a thickness of 100 μm was obtained and stored in deionized water for later use.

[0062] 2. Preparation of polyamide forward osmosis membrane (i.e., flat sheet membrane PA-MO) A 2.0 wt% aqueous solution of m-phenylenediamine (MPD) was prepared as the aqueous monomer solution, and a 0.15 wt% hexane solution of trimesoyl chloride (TMC) was prepared as the oil monomer solution. The smooth side of the polyethersulfone ultrafiltration membrane prepared in step 1 was inverted and immersed in the aqueous monomer solution. After standing for 2 minutes, it was removed, and excess liquid on the membrane surface was removed by absorbing it with filter paper. The membrane with the smooth side facing up was fixed in an acrylic modified plate assembly, ensuring that it was flat and wrinkle-free. Then, the oil monomer solution was dripped on it to completely cover the surface of the membrane, and it was allowed to react for 1 minute. The membrane was then removed and rinsed with hexane to remove unreacted residual monomers from the membrane surface, thus obtaining a polyamide forward osmosis membrane (i.e., a flat sheet membrane PA-MO).

[0063] 3. Preparation of carboxylated polyamide forward osmosis membrane Preparation of the mixed modification solution: Mix concentrated sulfuric acid, ethanol and deionized water to make the final concentration of sulfuric acid 1 mol / L, the volume fraction of ethanol 70%, and the remainder deionized water; completely immerse the polyamide forward osmosis membrane obtained in step 2 into the mixed modification solution and treat it in a sealed container at room temperature for 10 min; after treatment, take out the membrane and soak and wash it thoroughly with a large amount of deionized water (≥2 h) to remove residual sulfuric acid and solvent, and obtain the carboxylated polyamide forward osmosis membrane (i.e. modified membrane PA-M1).

[0064] Furthermore, the forward osmosis membrane module is connected to both the feed solution and the draw solution, which flow through tubing in the membrane tank at a cross-flow rate of 0.014 L / min under the impingement of a peristaltic pump. The draw solution is connected to an electronic analytical balance, and the change in the mass of the draw solution is recorded every 5 seconds during the test. After the test, the peristaltic pump is turned off, the mass value and conductivity value of the feed solution are read, and the solution inside the pipeline is drained for cleaning.

[0065] The water flux of the forward osmosis process is calculated using formula (1): (1) in, ∆m (kg) is ∆t (h) The change in the weight of the liquid drawn within a time period. ρ 0 (kg / L) is the density of water. A It is the effective area of ​​the membrane (m²) 2 ).

[0066] The reverse solute loss in the forward osmosis process is calculated using equations (2) and (3): (2) (3) in, A (m 2 () represents the effective membrane area. C 0 (g / L) and V 0 (L) represents the initial concentration and volume of the aspirated solution, respectively. C t (g / L) and V t (L) is t (h) The concentration and volume of the solution are measured at time (h). C t (g / L) was obtained by converting the conductivity measurement value (DDSJ-308F conductivity meter) using a standard curve.

[0067] The water flux results for the forward osmosis process using Ni-en, Ni-3en, NaCl, and NH4HCO3 solutions as draw solutions and deionized water as feed solution are as follows: Figure 2 and 3 As shown in the figure. The test results show that Ni-en has a higher water flux at the same concentration; under the conditions of 2 mol / L Ni-en as the draw solution, PA-M1 as the forward osmosis membrane, and the membrane orientation as PRO, the water flux reaches 44.9 LMH, which is 120% higher than that of the NaCl system.

[0068] Using Ni-en, Ni-3en, NaCl, and NH4HCO3 solutions as the draw solution, and deionized water as the feed solution, the results of the reverse solute loss in the forward osmosis process are as follows: Figure 4 and 5 As shown in the figure. The test results indicate that the back diffusion of Ni-en and Ni-3en is negligible under all conditions, while NaCl and NH4HCO3 exhibit severe back diffusion.

[0069] Example 3 Based on the test results of Example 2, a forward osmosis experiment was conducted to treat nickel-containing wastewater using a draw solution derived from nickel plating waste. Ni-en, NaCl, and NH4HCO3 at concentrations of 1 mol / L were used as draw solutions to evaluate the treatment performance of each draw solution for nickel-containing wastewater during the forward osmosis process.

[0070] First, prepare Ni with a single anion. 2+ (Nickel sulfate hexahydrate) feed solution, controlling Ni 2+ Concentration gradients of 50 ppm, 500 ppm, 1000 ppm, and 2000 ppm were used to investigate the effect of nickel ion concentration on forward osmosis separation efficiency. Simultaneously, to examine the influence of coexisting anions on mass transfer behavior during forward osmosis, a multi-anion mixed feed solution was prepared using nickel sulfate hexahydrate, nickel chloride hexahydrate, and nickel nitrate hexahydrate at a nickel ion mass ratio of 1:1:1 to obtain a homogeneous Ni... 2+ Mixed solutions with concentration gradients (50ppm, 500ppm, 1000ppm, 2000ppm). Forward osmosis experiments were conducted using the aforementioned draw solution and feed solution, respectively. The forward osmosis experiments for each feed solution were controlled to last for 30 minutes, and the water flux was calculated according to formula (1).

[0071] Furthermore, to examine the stability of the forward osmosis system under long-term operating conditions, Ni was used... 2+ A 1000 ppm nickel sulfate hexahydrate solution was used as the feed solution for a continuous 36-hour forward osmosis experiment. The change in the mass of the draw solution was recorded every 2 hours, and the water flux and average solute loss were calculated accordingly.

[0072] Short-term test results as follows Figure 6 As shown in the figure. The test results indicate that regardless of whether the feed solution is a single NiSO4 system or a NiSO4-NiCl2-Ni(NO3)2 mixed system, the water flux of all systems decreases with increasing feed solution concentration, but the decrease in Ni-en is smaller. Meanwhile, the Ni-en system exhibits extremely low solute back diffusion, maintaining a stable osmotic pressure difference. Therefore, it can maintain a high driving force under different types of feed solutions, demonstrating good system compatibility and performance stability.

[0073] Long-term test results such as Figure 7 As shown in the figure, the test results indicate that Ni-en exhibits a stable high water flux compared to NaCl and NH4HCO3. The figure shows that the system using NH4HCO3 as the draw solution exhibits significant performance degradation after 3 hours of operation, with green basic nickel carbonate precipitate appearing on the membrane surface, leading to scaling, decreased flux, and difficulty in rinsing to restore performance. While the NaCl system did not show precipitation, back diffusion was also significant, and the flux decreased markedly over time, especially under the high-permeability PA-M1 membrane.

[0074] In summary, this invention, based on the concept of "waste-to-waste treatment," designs and prepares nickel-ethylenediamine complexes for use in forward osmosis draw solution systems and for recycling. The excellent aqueous and ionic properties of the nickel-ethylenediamine complexes provide high osmotic pressure, ensuring high water flux; their stereocoagulation configuration and the three-dimensional hydrogen bond network in water ensure that they are not easily back-diffused. Furthermore, a "switch-on" precipitation recovery strategy based on solvent polarity control enables the regeneration and recycling of the nickel-ethylenediamine complexes at room temperature and pressure.

[0075] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0076] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a nickel-ethylenediamine complex extracting solution derived from nickel plating waste, characterized in that, The process includes the following steps: preparing nickel-ethylenediamine complexes and preparing the extraction solution; The method for preparing nickel-ethylenediamine complexes is as follows: ethylenediamine is added dropwise to an aqueous solution of nickel ions. After the addition is complete, the mixture is kept at a temperature of 40-45°C to obtain a reaction solution. An organic solvent is added to the reaction solution to precipitate the mixture. The solid is then separated and collected. The solid is washed and dried to obtain the nickel-ethylenediamine complex. The method for preparing the draw solution is to mix a nickel-ethylenediamine complex with deionized water to obtain a nickel-ethylenediamine complex draw solution with a nickel-ethylenediamine complex concentration of 0.1-2 mol / L, which is derived from nickel plating waste.

2. The method for preparing a nickel-ethylenediamine complex extracting solution derived from nickel plating waste according to claim 1, characterized in that, In the preparation of the nickel-ethylenediamine complex, the molar ratio of nickel ions to ethylenediamine is 1:1 or 1:3.5-4.

3. The method for preparing the nickel-ethylenediamine complex extracting solution based on nickel plating waste according to claim 1, characterized in that, In the preparation of the nickel-ethylenediamine complex, the ethylenediamine is added over a period of 2-3 minutes. After the ethylenediamine is added, the reaction is kept at 40-45℃ for 3-5 hours.

4. The method for preparing a nickel-ethylenediamine complex extracting solution based on nickel plating waste according to claim 1, characterized in that, In the preparation of the nickel-ethylenediamine complex, the nickel ion concentration in the nickel ion aqueous solution is 4.8-5.2 mol / L.

5. The method for preparing a nickel-ethylenediamine complex extracting solution derived from nickel plating waste according to claim 1, characterized in that, In the preparation of the nickel-ethylenediamine complex, the nickel ions in the nickel ion aqueous solution are provided by nickel nitrate.

6. The method for preparing a nickel-ethylenediamine complex extracting solution based on nickel plating waste according to claim 1, characterized in that, In the preparation of the nickel-ethylenediamine complex, the organic solvent used for precipitation is acetone or ethanol.

7. A nickel-ethylenediamine complex extraction solution based on nickel plating waste, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. An application of the nickel-ethylenediamine complex extracting solution derived from nickel plating waste as described in claim 7, characterized in that, The nickel-containing wastewater was treated by forward osmosis using the extractant based on nickel-ethylenediamine complex derived from nickel plating waste.

9. The application of the nickel-ethylenediamine complex extracting solution derived from nickel plating waste according to claim 8, characterized in that, The nickel ion content in the nickel-containing wastewater is 0-2000 ppm.

10. The application of the nickel-ethylenediamine complex extracting solution derived from nickel plating waste according to claim 8, characterized in that, It also includes the following steps: recycling and regeneration; The method for recycling and regeneration is as follows: after the forward osmosis treatment of nickel-containing wastewater is completed, an organic solvent is added to the draw solution of the nickel-ethylenediamine complex to be treated for precipitation, and the solids are separated and collected. The solids are washed and dried to recover the nickel-ethylenediamine complex. Then, the nickel-ethylenediamine complex is mixed with deionized water to prepare a new draw solution of nickel-ethylenediamine complex with a concentration of 0.1-2 mol / L, which is then used again for forward osmosis treatment of nickel-containing wastewater.

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