A method for purifying nickel-containing wastewater based on ion exchange resin

Abstract

The application discloses a method for purifying nickel-containing wastewater based on ion exchange resin, and the method comprises the following steps: (a) pretreating the nickel-containing wastewater; (b) adsorbing by using a cation resin column; (c) deeply purifying by using a chelating resin column; and (d) sequentially performing air-water pulse backflushing, acid regeneration, gradient transformation and two-stage electrolysis recovery. The pretreatment of the nickel-containing wastewater provides favorable conditions for subsequent resin adsorption; the two-resin synergistic adsorption mode removes nickel ions in the wastewater; the air-water pulse backflushing step effectively prevents resin blockage and improves the use efficiency of the resin; the acid regeneration step realizes efficient regeneration of the resin; the gradient transformation step further optimizes the adsorption performance of the resin; and the two-stage electrolysis recovery step not only realizes effective recovery of nickel resources, but also improves the electrolysis efficiency, so that the purification method has significant technical advantages and application prospect.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a method for purifying nickel-containing wastewater based on ion exchange resin. Background Technology

[0002] Ni 2+ The wastewater from nickel plating poses a serious threat to human health and the ecological environment. Common treatment methods for nickel-containing wastewater include chemical precipitation, vacuum evaporation recovery, electrodialysis, reverse osmosis, and ion exchange resin adsorption. Chemical precipitation is low-cost, but the resulting solid waste requires secondary treatment; vacuum evaporation is energy-intensive; electrodialysis and reverse osmosis require significant equipment investment and energy consumption, and also suffer from membrane fouling issues. Ion exchange technology is widely used due to its advantages such as good effluent quality, the ability to recover useful substances, and suitability for treating high-volume, low-concentration nickel plating wastewater.

[0003] The main functions of ion exchange in nickel plating wastewater treatment are: (1) removing heavy metal nickel ions to meet increasingly stringent emission standards; (2) recovering valuable nickel metal from wastewater; (3) improving water recycling rate and saving increasingly scarce water resources; and (4) reducing environmental pollution.

[0004] Ion exchange resins are insoluble polymers with a three-dimensional structure; their functional groups can undergo exchange reactions with ions in water. Ni in nickel plating wastewater... 2+ Ions are adsorbed using cation exchange resins. The resin used can be either a strongly acidic cation exchange resin or a weakly acidic cation exchange resin. When using a weakly acidic cation exchange resin, the resin is usually converted to the Na form.

[0005] Ni 2+ When wastewater flows through a Na-type weakly acidic cation exchange resin layer, the following exchange reaction occurs:

[0006] 2R-COONa+Ni 2+ →(R-COO)2Ni+2Na +

[0007] Ni in water 2+ The Na+ ions are adsorbed onto the resin, and then enter the water. When the entire resin layer is in contact with Ni... 2+ When the exchange reaches equilibrium, it is regenerated with a certain concentration of HCl or H2SO4.

[0008] (R-COO)2Ni+H2SO4→2R-COOH+NiSO4

[0009] At this point, the resin is in the H-form and needs to be converted to the Na-form using NaOH, as follows:

[0010] R-COOH + NaOH → RCOOH + H₂O

[0011] The resin can then be put back into operation for the next cycle. The wastewater can be treated and reused in the cleaning tank, and the nickel sulfate obtained from the elution can be purified and reused in the plating tank.

[0012] Existing technologies for treating nickel-containing wastewater using ion exchange resins suffer from problems such as short resin lifespan and low resin regeneration efficiency. Summary of the Invention

[0013] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for purifying nickel-containing wastewater based on ion exchange resin, which effectively removes nickel ions from the wastewater and realizes wastewater purification and resource recovery.

[0014] Specifically, the first aspect of this application provides a method for purifying nickel-containing wastewater based on ion exchange resin, comprising the following steps:

[0015] (a) Pretreatment of nickel-containing wastewater;

[0016] (b) Adsorption using a cation exchange resin column;

[0017] (c) Deep purification using chelating resin columns;

[0018] (d) Perform gas-water pulse backflushing → acid regeneration → gradient conversion → two-stage electrolytic recovery in sequence.

[0019] Furthermore, the pretreatment is a citrate-sodium acetate buffer solution to adjust the pH of the wastewater to 4.7-4.9.

[0020] Furthermore, the pretreatment also includes adding an oxidant to the wastewater to make the ORP in the water ≥ 450mV.

[0021] Further, in step (b), the flow rate of the nickel-containing wastewater through the D418 cation exchange resin column is calculated using the formula V = 13.5 - 0.075 × C, where C is the influent Ni content. 2+ Concentration (mg / L).

[0022] Further, in step (c) when Ni in the effluent... 2+ When the concentration is >0.005 mg / L, use the S930 chelating resin column for pulse adsorption, run for 120-150 min, pause for 15-20 min, and repeat this cycle.

[0023] Further, in step (d), the gas-water pulse backflushing is performed using nitrogen and water at a flow rate of 10-20 BV / h, wherein the gas pressure is 0.12-0.15 MPa; and / or the expansion rate is 35%-40%; and / or the duration is 20-30 min.

[0024] Further, the regenerated solution in step (d) of acid regeneration includes 3-6% sulfuric acid, 0.1-0.15% citric acid, and 0.05-0.08% corrosion inhibitor, and / or

[0025] The corrosion inhibitor is one of benzotriazole, sodium thiocyanate, or diethylthiourea.

[0026] Furthermore, in step (d), the acid regeneration temperature is 40-48°C, and / or the flow rate is 4-6 BV / h.

[0027] Furthermore, the gradient transformation in step (d) includes a first stage and a second stage, wherein:

[0028] First stage: 2-4% MgCl2 solution, and / or a flow rate of 2-4 BV / h; and / or

[0029] Second stage: a mixture of 1-3% MgCl2 and 0.3-0.8% NaOH, and / or a flow rate of 3-5 BV / h.

[0030] Furthermore, the two-stage electrolytic recovery in step (d) includes primary electrolysis and secondary refining, wherein:

[0031] First-stage electrolysis: current density 280-300 A / m 2 Voltage 3.2-3.8V; and / or

[0032] Secondary refining: Current density 150-160 A / m 2 Voltage 2.8-3.2V.

[0033] The present invention has the following beneficial effects:

[0034] The pretreatment step of this invention adjusts the pH of the wastewater using a citrate-sodium acetate buffer solution and adds an oxidant to increase the oxidation-reduction potential (ORP) of the wastewater, providing favorable conditions for subsequent resin adsorption. A dual-resin synergistic adsorption method is employed: the selective adsorption of nickel ions from the wastewater by the cation exchange resin column removes the nickel ions; when the cation exchange resin column is saturated, the chelate resin column is activated for deep purification, ensuring the purification effect. The gas-water pulse backflushing step effectively prevents resin clogging and improves resin utilization efficiency. The acid regeneration step achieves efficient resin regeneration through specific regeneration solution composition and temperature control. The gradient transformation step further optimizes the resin adsorption performance by gradually adjusting the solution composition and flow rate. Finally, the two-stage electrolysis recovery step not only achieves effective recovery of nickel resources but also improves electrolysis efficiency. In summary, the purification method of this application has significant technical advantages and application prospects. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0036] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0037] This application provides a method for purifying nickel-containing wastewater based on ion exchange resin, comprising the following steps:

[0038] (a) Pretreatment of nickel-containing wastewater;

[0039] (b) Adsorption using a cation exchange resin column;

[0040] (c) Deep purification using chelating resin columns;

[0041] (d) Perform gas-water pulse backflushing → acid regeneration → gradient conversion → two-stage electrolytic recovery in sequence.

[0042] The nickel-containing wastewater purification method of this invention first pre-treats the nickel-containing wastewater, adjusting its pH value and redox potential to provide a good foundation for subsequent treatment steps. The cation exchange resin column is a D418 cation exchange resin column, and the chelating resin column is an S930 chelating resin column. After pre-treatment, the D418 cation exchange resin column is used to selectively adsorb nickel ions in the wastewater, effectively removing most of the nickel ions. When the D418 cation exchange resin column reaches approximately 85% saturation, the S930 chelating resin column is activated for deep purification, ensuring complete removal of nickel ions from the wastewater. In the gas-water pulse backwash step, the combined backwashing of nitrogen and water effectively prevents resin clogging and improves resin utilization efficiency. The subsequent acid regeneration step, utilizing a specific regeneration solution composition and temperature control, achieves efficient resin regeneration, preparing it for the next round of adsorption. The gradient transition step further optimizes the resin's adsorption performance by gradually adjusting the solution composition and flow rate, enabling it to better meet the needs of wastewater treatment. Finally, in the two-stage electrolytic recovery process, the synergistic effect of primary electrolysis and secondary refining not only achieves effective recovery of nickel resources, but also improves electrolysis efficiency and reduces energy consumption.

[0043] In this embodiment, the pretreatment is a citrate-sodium acetate buffer solution to adjust the wastewater pH to 4.7-4.9. Preferably, the wastewater pH is 4.8. The pretreatment step is designed considering the relationship between nickel ions in the wastewater and the resin adsorption efficiency. By precisely adjusting the pH value to 4.7-4.9, not only is the form of nickel ions optimized, but the selective adsorption capacity of the D418 cation exchange resin column for nickel ions is also improved.

[0044] In this embodiment, the pretreatment further includes adding an oxidant to the wastewater to ensure an ORP ≥ 450 mV, thereby stabilizing nickel ions. The oxidant is one of ammonium persulfate, Fenton's reagent, or sodium hypochlorite. The oxidant is added in batches to the reaction tank, with mechanical stirring at 60 rpm, maintaining the reaction time at least 25 minutes, and the ORP value is monitored in real time. Specifically, the ORP value is ≥ 450 mV for the ammonium persulfate system and ≥ 550 mV for the Fenton system.

[0045] In this embodiment, a primary column of D418 cation exchange resin and a secondary column of S930 chelate resin are used for adsorption. The secondary column is automatically started when the adsorption saturation of the primary column reaches 85%, which is 15% earlier than the traditional method. The secondary column adopts pulse adsorption: it is paused for 15 minutes every 2 hours to avoid channeling effect.

[0046] In step (b), the flow rate of the nickel-containing wastewater through the D418 cation exchange resin column is calculated using the formula V = 13.5 - 0.075 × C, where C is the influent Ni content. 2+ Concentration mg / L. When the influent Ni 2+At a concentration of 50 mg / L, the flow rate = 13.5 - 0.075 × 50 = 9.75 BV / h, which ensures sufficient resin adsorption while avoiding incomplete adsorption due to excessively high flow rate. By precisely controlling the flow rate, this method achieves highly efficient removal of nickel ions from wastewater, while optimizing resin utilization efficiency. 2+ The concentration is ≤0.005mg / L, meeting the effluent standard.

[0047] In this embodiment, step (c) involves the Ni in the effluent... 2+ When the concentration is >0.005 mg / L, the S930 chelating resin column is activated for pulse adsorption, running for 120-150 minutes, then pausing for 15-20 minutes, and repeating this cycle. The pulse adsorption mode of the S930 chelating resin column ensures continuous and efficient resin operation during the deep purification process, avoiding resin saturation and decreased adsorption efficiency caused by prolonged continuous operation. Through intermittent operation and pauses, this mode not only optimizes the resin's adsorption performance but also extends its lifespan. Furthermore, this mode reduces the resin regeneration frequency, thereby lowering treatment costs. After the deep purification step, the nickel ion concentration in the wastewater is further reduced, ensuring the purification effect.

[0048] In this embodiment, step (d) involves a gas-water pulse backflushing process using nitrogen and water at a flow rate of 10-20 BV / h, with a gas pressure of 0.12-0.15 MPa, a resin expansion rate of 35%-40%, and a duration of 20-30 minutes. The purpose of the gas-water pulse backflushing is to loosen the resin layer. A dedicated backflushing pump is used, controlling the water flow rate at 10-20 BV / h, employing a gas-water pulse mode: 30 seconds of aeration followed by 10 seconds of aeration, then 60 seconds of water flow, cycling until the effluent turbidity is ≤10 NTU. This gas-water pulse backflushing step not only effectively removes impurities and blockages from the resin layer but also maintains the resin in a loose state, which is beneficial for subsequent adsorption processes. Furthermore, this step, through precise control of the gas pressure and expansion rate, ensures the consistency and stability of the backflushing effect, avoiding resin damage or efficiency reduction due to improper operation.

[0049] In this embodiment, the regenerated solution in step (d) comprises 3-6% sulfuric acid, 0.1-0.15% citric acid, and 0.05-0.08% corrosion inhibitor, with the remainder being water. The corrosion inhibitor is one of benzotriazole, sodium thiocyanate, or diethylthiourea.

[0050] Furthermore, the acid regeneration temperature is 40-48℃ and the flow rate is 4-6 BV / h. The temperature of the regenerated solution is controlled within this range, ensuring that the effective components of the regenerated solution can fully dissolve and function, while avoiding resin structure damage or performance degradation due to excessively high temperatures. During acid regeneration, precise control of the regenerated solution flow rate at 4-6 BV / h ensures sufficient contact and reaction between the regenerated solution and the resin, thereby achieving efficient resin regeneration. After regeneration, the resin's adsorption performance is restored, preparing it for subsequent adsorption processes.

[0051] In this embodiment, the gradient transformation in step (d) includes a first stage and a second stage, wherein:

[0052] First stage: 2-4% MgCl2 solution, flow rate 2-4 BV / h, time 30-50 min;

[0053] Second stage: A mixture of 1-3% MgCl2 and 0.3-0.8% NaOH, with a flow rate of 3-5 BV / h and a time of 20-60 min.

[0054] The process ended when the change rate of effluent conductivity was less than 5% / 10 min. The gradient transition step was designed to optimize the resin's adsorption performance. In the first stage, a 2-4% MgCl2 solution was used for transition, and the resin's adsorption performance was initially adjusted by controlling the flow rate and time. Subsequently, in the second stage, a mixture of 1-3% MgCl2 and 0.3-0.8% NaOH was used for further transition. This step not only optimized the resin's adsorption performance but also ensured that the resin could better meet the needs of wastewater treatment. By gradually adjusting the solution composition and flow rate, the gradient transition step achieved fine control over the resin's adsorption performance, improving the efficiency and quality of wastewater treatment.

[0055] In this embodiment, the two-stage electrolytic recovery in step (d) includes primary electrolysis and secondary refining, wherein:

[0056] First-stage electrolysis: current density 280-300 A / m 2 The voltage is 3.2-3.8V; the electrolyte temperature is 54-56℃; and the cathode plate has a titanium-based coating.

[0057] Secondary refining: Current density 150-160 A / m 2 The voltage is 2.8-3.2V, the electrolyte temperature is 58-62℃, and the cathode plate is made of 316L stainless steel.

[0058] The electrolysis process separates and recovers nickel ions and other impurities adsorbed on the resin. The synergistic effect of primary electrolysis and secondary refining not only improves the recovery rate of nickel resources but also ensures the stability and efficiency of the electrolysis process. During primary electrolysis, a high current density and suitable voltage range rapidly initiate the electrolytic reaction, effectively removing impurities from the resin. Simultaneously, precise control of the electrolyte temperature prevents decreased electrolysis efficiency or equipment damage caused by excessively high or low temperatures. The cathode plate uses a titanium-based coating material, whose excellent corrosion resistance and conductivity further ensure the smooth operation of the electrolysis process.

[0059] Secondary refining is a more refined treatment of primary electrolysis. By reducing the current density and adjusting the voltage to a more optimized range, secondary refining can more thoroughly remove residual impurities from the resin, ensuring optimal resin regeneration. Simultaneously, adjusting the electrolyte temperature and selecting 316L stainless steel as the cathode material further enhances the refining effect and the equipment's durability. After secondary refining, the resin's adsorption capacity is fully restored, providing strong support for subsequent adsorption processes, thereby extending the overall lifespan of the resin and significantly reducing wastewater treatment costs.

[0060] Example 1

[0061] A method for purifying nickel-containing wastewater based on ion exchange resin includes the following steps:

[0062] (a) Pretreatment of nickel-containing wastewater: citrate-sodium acetate buffer solution was used to adjust the pH of the wastewater to 4.8. Ammonium sulfate was added to the wastewater to make the ORP in the water ≥ 450mV.

[0063] (b) Adsorption using a D418 cation exchange resin column, Ni in the effluent 2+ Concentration less than 0.005 mg / L;

[0064] (c) When Ni in the water is discharged 2+ When the concentration is >0.005 mg / L, the S930 chelating resin column is used for pulse adsorption, running for 120 min, pausing for 15 min, and repeating this cycle.

[0065] (d) Perform gas-water pulse backflushing → acid regeneration → gradient conversion → two-stage electrolysis recovery in sequence;

[0066] The air-water pulse backwash uses nitrogen and water at a flow rate of 12 BV / h, with an air pressure of 0.13 MPa; the resin expansion rate is 35%, the duration is 25 min, and the air-water pulse mode is used, that is, 30s of air supply → 10s of air stop → 60s of water supply, and the cycle ends when the turbidity of the effluent is ≤10 NTU.

[0067] The regeneration solution in the acid regeneration comprises 4% sulfuric acid, 0.12% citric acid, and 0.06% benzotriazole, with the remainder being water;

[0068] The gradient transformation includes a first stage and a second stage, wherein:

[0069] First stage: 3% MgCl2 solution, flow rate 3 BV / h, time 40 min;

[0070] Second stage: a mixture of 2% MgCl2 and 0.5% NaOH, at a flow rate of 4 BV / h, for 30 min;

[0071] The two-stage electrolytic recovery includes primary electrolysis and secondary refining, wherein:

[0072] First-stage electrolysis: current density 300 A / m 2 Voltage 3.5V; electrolyte temperature 55℃; cathode plate with titanium-based coating;

[0073] Secondary refining: Current density 150A / m 2 The voltage is 3V, the electrolyte temperature is 60℃, and the cathode plate is made of 316L stainless steel.

[0074] Example 2

[0075] This embodiment is basically the same as Embodiment 1, except that the gas-water pulse backflushing is performed using nitrogen and water at a flow rate of 18 BV / h, with a gas pressure of 0.15 MPa, a resin expansion rate of 40%, and a duration of 30 min.

[0076] Example 3

[0077] This embodiment is basically the same as Embodiment 1, except that the regeneration solution in the acid regeneration includes 5% sulfuric acid, 0.15% citric acid and 0.07% benzotriazole, with the remainder being water.

[0078] Example 4

[0079] This embodiment is basically the same as Embodiment 1, except that the gradient transformation includes a first stage and a second stage, wherein:

[0080] First stage: 3% MgCl2 solution, flow rate 4 BV / h, time 45 min;

[0081] Second stage: a mixture of 3% MgCl2 and 0.7% NaOH, at a flow rate of 5 BV / h, for 60 min.

[0082] Example 5

[0083] This embodiment is basically the same as Embodiment 1, except that the two-stage electrolytic recovery includes primary electrolysis and secondary refining, wherein:

[0084] First-stage electrolysis: current density 280 A / m 2 The voltage is 3.2V; the electrolyte temperature is 55℃; and the cathode plate has a titanium-based coating.

[0085] Secondary refining: Current density 150A / m 2 The voltage is 2.8V, the electrolyte temperature is 61℃, and the cathode plate is made of 316L stainless steel.

[0086] Comparative Example 1

[0087] This comparative example is basically the same as Example 1, except that only the primary D418 cation exchange resin column is used for adsorption, and the secondary S930 chelating resin column is not used for adsorption.

[0088] Comparative Example 2

[0089] This comparative example is basically the same as Example 1, except that the air-water pulse backflushing process is not performed.

[0090] Comparative Example 3

[0091] This comparative example is basically the same as Example 1, except that the acid regeneration process is not performed.

[0092] Comparative Example 4

[0093] This comparative example is basically the same as Example 1, except that the gradient transformation process is not performed.

[0094] Comparative Example 5

[0095] This comparative example is basically the same as Example 1, except that the two-stage electrolytic recovery process is not performed.

[0096] The experiments were conducted according to the methods of Example 5 and Comparative Example 5 to test the nickel adsorption capacity and the service life of the resin column. The results are shown in the table below:

[0097]

[0098] As can be seen from the table above, the methods described in Examples 1-5 of this invention for treating nickel-containing wastewater achieve comprehensive optimization and efficient utilization of the resin adsorption performance. Firstly, the precise adjustment of the wastewater pH and the addition of oxidant in the pretreatment step not only optimizes the form of nickel ions but also improves the resin's selective adsorption capacity for them. Secondly, precise control of the wastewater flow rate through the resin column ensures sufficient resin adsorption, avoiding incomplete adsorption. In the deep purification step, the pulse adsorption mode further optimizes the resin's adsorption performance and extends its service life. Furthermore, the gas-water pulse backflushing step effectively removes impurities and blockages from the resin layer, maintaining the resin's loose state, which is beneficial for subsequent adsorption processes. In the acid regeneration step, precise control of the composition, temperature, and flow rate of the regeneration solution achieves efficient resin regeneration, preparing it for the next round of adsorption. The gradient transition step further optimizes the resin's adsorption performance by gradually adjusting the solution composition and flow rate, enabling it to better meet the needs of wastewater treatment. Finally, in the two-stage electrolytic recovery process, the synergistic effect of primary electrolysis and secondary refining not only improves the recovery rate of nickel resources but also ensures the stability and efficiency of the electrolysis process. These factors combined result in the excellent performance of this method in treating nickel-containing wastewater, achieving a nickel adsorption capacity of up to 120 g / L and resin circulation times exceeding 290 times, significantly improving the efficiency and quality of wastewater treatment.

[0099] In Comparative Example 1, the lack of a two-stage S930 chelating resin column for deep purification resulted in incomplete removal of nickel ions and limited adsorption capacity. In Comparative Example 2, the gas-water pulse backwashing step was omitted, failing to effectively remove impurities and blockages from the resin layer, thus affecting the resin's adsorption efficiency and lifespan. In Comparative Example 3, the absence of an acid regeneration process led to poor resin regeneration, failing to restore its optimal adsorption performance. In Comparative Example 4, the lack of a gradient conversion process prevented precise control of the resin's adsorption performance, making it difficult to adapt to changing wastewater treatment needs. In Comparative Example 5, the omission of a two-stage electrolysis recovery step not only reduced the nickel resource recovery rate but may also affect the stability and efficiency of the electrolysis process. These factors collectively resulted in low nickel adsorption capacity and a limited number of resin cycles in the comparative examples.

[0100] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for purifying nickel-containing wastewater based on ion exchange resin, characterized in that, Includes the following steps: (a) Pretreatment of nickel-containing wastewater; (b) Adsorption was performed using a D418 cation exchange resin column; (c) Deep purification was performed using an S930 chelating resin column; (d) Perform gas-water pulse backflushing, acid regeneration, gradient conversion and two-stage electrolytic recovery in sequence; The gas-water pulse backflushing is performed using nitrogen and water at a flow rate of 10-20 BV / h, with a gas pressure of 0.12-0.15 MPa, an expansion rate of 35%-40%, and a duration of 20-30 minutes. The air-water pulse backwash adopts a cycle mode of 30s of air supply, 10s of air supply stoppage, and 60s of water supply; Gradient transformation includes a first stage and a second stage, in which: First stage: Conversion is carried out using 2-4% MgCl2 solution at a flow rate of 2-4 BV / h; The second stage involves using a mixture of 1-3% MgCl2 and 0.3-0.8% NaOH for conversion at a flow rate of 3-5 BV / h.

2. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, The pretreatment involves adjusting the pH of the wastewater to 4.7-4.9 using a citrate-sodium acetate buffer solution.

3. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 2, characterized in that, The pretreatment also includes adding an oxidant to the wastewater to make the ORP in the water ≥ 450mV.

4. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, In step (b), the flow rate of the nickel-containing wastewater through the D418 cation exchange resin column is calculated using the formula V = 13.5 - 0.075 × C, where C is the influent Ni content. 2+ Concentration, in mg / L.

5. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, Step (c) When Ni in the effluent... 2+ When the concentration is >0.005 mg / L, use the S930 chelating resin column for pulse adsorption, run for 120-150 min, pause for 15-20 min, and repeat this cycle.

6. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, The regenerated solution in step (d) of acid regeneration includes 3-6% sulfuric acid, 0.1-0.15% citric acid, and 0.05-0.08% corrosion inhibitor; The corrosion inhibitor is one of benzotriazole, sodium thiocyanate, or diethylthiourea.

7. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, In step (d), the acid regeneration temperature is 40-48℃ and the flow rate is 4-6 BV / h.

8. The method for purifying nickel-containing wastewater based on ion exchange resin according to claim 1, characterized in that, Step (d) in the two-stage electrolytic recovery includes primary electrolysis and secondary refining, wherein: First-stage electrolysis: current density 280-300 A / m 2 Voltage 3.2-3.8V; Secondary refining: Current density 150-160 A / m 2 Voltage 2.8-3.2V.

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