Method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid

Abstract

The invention relates to the technical field of waste liquid treatment, in particular to a method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid, which comprises the following steps: S1, nanofiltration: carrying out nanofiltration separation on chemical nickel plating waste water by using a roll type nanofiltration membrane to obtain nickel-containing waste water and waste water containing hypophosphorous acid and ammonia; s2, bipolar membrane electrodialysis: setting an arrangement mode of a bipolar membrane electrodialysis system as follows: sequentially arranging an anode, a first bipolar membrane, an anionic membrane, a cationic membrane, a second bipolar membrane and a cathode, introducing wastewater containing hypophosphorous acid and ammonia into a desalination chamber, and adding deionized water into an acid chamber and an alkali chamber to obtain a hypophosphorous acid solution and ammonia gas; separation of hypophosphorous acid and ammonia is realized; according to the method, hypophosphite and ammonium in the chemical nickel-plating waste liquid are efficiently separated, and the method has important significance on improving the resource utilization efficiency of phosphorus and ammonia in the chemical nickel-plating waste liquid and reducing the treatment difficulty and treatment cost of the chemical nickel-plating waste liquid.

Description

Technical Field

[0001] The invention relates to the technical field of waste liquid treatment, in particular to a method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid. Background Art

[0002] The composition of chemical nickel plating waste liquid is complex. In addition to heavy metal organic complexes such as EDTA-Ni and nickel citrate, it also contains monovalent ions such as hypophosphite and ammonia. At present, the treatment of chemical nickel plating waste liquid and wastewater is mainly based on the Fenton oxidation method, which produces a large amount of sludge and seriously wastes hypophosphite and ammonia resources. If the hypophosphite and ammonium in the chemical nickel plating waste liquid can be efficiently separated, it will be of great significance to improve the resource utilization efficiency of phosphorus and ammonia in the chemical nickel plating waste liquid and reduce the difficulty and cost of chemical nickel plating waste liquid treatment.

[0003] Nanofiltration (NF) is a pressure-driven membrane technology between ultrafiltration and reverse osmosis. It has an appropriate membrane pore size (the pore size of nanofiltration membrane is usually between 0.5-1 nanometers) and a charge repulsion mechanism, which enables the nanofiltration membrane to effectively retain large molecular organic substances (>150Da) and multivalent ions, while allowing monovalent ions (NH4 + 、NO3 - 、H2PO2 - ) This selectivity makes nanofiltration membrane have good prospects in separating EDTA-Ni from other components in chemical nickel plating wastewater.

[0004] Bipolar membrane electrodialysis (BMED) is an advanced membrane separation technology that can separate anions and cations in wastewater through electric field without using chemical reagents and generate corresponding acids and bases. + ) and hypophosphite (H2PO2 - ) and other molecular aspects have significant advantages.

[0005] Therefore, the present invention designs a method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid to improve the separation efficiency by combining nanofiltration membrane and electrodialysis technology. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid.

[0007] A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid comprises the following steps:

[0008] S1. Nanofiltration:

[0009] First, the pH of the chemical nickel plating waste liquid is adjusted to 5-6, and then a decomplexing agent accounting for 0.8-1% of the total volume of the chemical nickel plating waste liquid is added, and stirred for 15-25 minutes; when the pH of the chemical nickel plating waste liquid begins to increase, UV light is introduced and stirring is continued until the pH no longer changes;

[0010] The method of introducing UV light is as follows: based on one minute, the pH change rate is less than 0.05, and the intensity of UV light is 20-25 μmol·m -2 ·s -1 The increase was 3-5 μmol·m per minute. -2 ·s -1 The light intensity was continuously irradiated until the pH change rate was 0.05 ≤, and the intensity of UV light was reduced to 5-10 μmol·m -2 ·s -1 ;

[0011] The chemical nickel plating wastewater is subjected to nanofiltration separation at 20-30°C and 5-15MPa by using a rolled nanofiltration membrane to obtain nickel-containing wastewater, hypophosphorous acid-containing wastewater and ammonia-containing wastewater;

[0012] S2, Bipolar membrane electrodialysis:

[0013] The arrangement of the bipolar membrane electrodialysis system is set as follows: the anode, the first bipolar membrane, the anion membrane, the cationic membrane, the second bipolar membrane, and the cathode are arranged in sequence, the area between the first bipolar membrane and the anion membrane is the acid chamber, the area between the cationic membrane and the second bipolar membrane is the alkali chamber, and the area between the anion membrane and the cationic membrane is the desalination chamber;

[0014] The wastewater containing hypophosphorous acid and ammonia is passed into the desalination chamber, and deionized water is added to both the acid chamber and the alkali chamber, and the volume ratio of the deionized water in the acid chamber to the alkali chamber is 1:2-3, wherein the voltage of the bipolar membrane electrodialysis is 10-30V, and the current density is 15-25A / m 2 , hypophosphite ions enter the acid chamber, and ammonium ions enter the base chamber, further obtaining hypophosphorous acid solution and ammonia gas, until ammonia gas is no longer generated and bipolar membrane electrodialysis is completed, thereby achieving separation of hypophosphorous acid and ammonia.

[0015] Furthermore, the rolled nanofiltration membrane adopts one of NF90, DK8040F-30P and TM620N-400.

[0016] Description: NF90 nanofiltration membrane has no effect on Ni 2+The wastewater has a good treatment effect, with a removal rate of over 98%; the DK8040F-30P nanofiltration membrane is famous for its excellent mechanical strength and anti-pollution performance, with low requirements for influent quality, low operating pressure, low energy consumption, and high flux. It can effectively remove impurities such as microorganisms, colloids, and suspended matter in the water; TM620N-400 is acid-resistant, corrosion-resistant, and has high chemical stability. It can effectively purify high-concentration heavy metals such as nickel in wastewater, achieving more than 90% wastewater recovery and purification.

[0017] Furthermore, the anion membrane is FAA-PK-130 or AMI-7001S, and the cationic membrane is FKB-PK-130 or FKL-PK-130.

[0018] Description: The above membrane models are able to selectively transmit anions or cations and can effectively separate specific anionic species or cationic species from a solution.

[0019] Furthermore, the first bipolar membrane and the second bipolar membrane are both made of one of BPM-6012-50, BMP-200 and JED-6012-40.

[0020] Note: The above bipolar membranes are all capable of providing efficient ion exchange and separation during electrodialysis.

[0021] Furthermore, the total time T of the wastewater containing hypophosphorous acid and ammonia passing into the desalination chamber is divided into a plurality of time periods of equal length: t1, t2, t3, ...t n , n = 6 to 15; the T value is 30 to 45 min, the t1....t n The value of is 3 to 5 minutes, and the ammonia generation rate V in the alkali chamber is detected in each time period. t ; In the first time period t1, the introduction rate of the wastewater containing hypophosphorous acid and ammonia is 4-6L / min, the temperature in the alkali chamber is 20-25°C, and the pressure in the alkali chamber is 5-10MPa;

[0022] When V t-1 -V t ≤0, compared with the previous time period, the temperature in the alkali chamber is increased by 1.4 to 1.6 times, the pressure in the alkali chamber is reduced by 50 to 60%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is increased by 15 to 20%;

[0023] When 0<V t-1 -V t When compared with the previous time period, the temperature in the alkali chamber is kept unchanged, the pressure in the alkali chamber is reduced by 10-20%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is reduced by 5-10%.

[0024] Note: After nanofiltration, a small amount of nickel may remain in the wastewater. By testing the generation rate of ammonia in different time periods, when the generation rate changes, it may be affected by nickel. When the rate decreases, the fluidity of the solution is increased by increasing the temperature, the viscosity is reduced, thereby accelerating the migration of ions and improving the separation efficiency. By reducing the pressure, the boiling point of water can be reduced, which is conducive to the volatilization and collection of ammonia, and further improving the separation rate of ammonia. Increasing the wastewater introduction rate can treat more wastewater per unit time, increase the supply of ammonium ions, and promote the generation of ammonia.

[0025] When the rate increases, continued pressure reduction can maintain the ammonia production rate and keep it efficient; however, too high ammonia production rate may increase the burden on the ion exchange membrane and reduce the performance of the membrane. Therefore, by reducing the feed rate, the workload of the membrane can be reduced, the risk of membrane fouling can be reduced, and the ammonia concentration in the system can be reduced, reducing the impact of gas-liquid equilibrium, which helps ammonia escape from the wastewater more easily and be captured by the collection system.

[0026] Furthermore, when V t-1 -V t ≤-20%~-30%V t When the deionized water in the alkali chamber is firstly subjected to plasma activation treatment to obtain plasma activated water, and the turbulence intensity of the plasma activated water is set to 5-6%; wherein the plasma activation treatment time is 1-2 minutes, and the power is 600-700W;

[0027] When -20%~-30%V t <V t-1 -V t ≤0, firstly perform plasma activation treatment on the deionized water in the alkali chamber to obtain plasma activated water, and set the turbulence intensity of the plasma activated water to 2-3%; wherein, the plasma activation treatment time is 0.5-1min, and the power is 450-550W.

[0028] Description: Plasma activation can increase the activity of water and promote hydrolysis reaction, thus contributing to the generation of ammonia. When the ammonia generation rate decreases, activation can stimulate the release of ammonia and improve the ammonia recovery efficiency. However, when the ammonia generation rate no longer decreases significantly, weakening plasma activation and turbulence intensity can reduce power consumption and help reduce overall operating costs. Adjusting the plasma activation degree and turbulence intensity according to the real-time changes in the ammonia generation rate can more finely control the electrodialysis process, ensure the optimization of reaction conditions, and avoid excessive consumption of resources.

[0029] Furthermore, the method of plasma activation treatment is: spraying plasma prepared by a low-temperature plasma generator into deionized water in an alkali chamber.

[0030] Note: Spraying plasma produced by a low-temperature plasma generator into water can produce so-called low-temperature plasma active water. This active water contains active oxides that help produce ammonia.

[0031] Compared with the existing method for separating nickel, hypophosphorous acid and ammonia in wastewater, the beneficial effects of the present invention are:

[0032] (1) The separation method of the present invention firstly performs an acidification treatment to effectively release nickel at a relatively low pH value, and then adds a decomplexing agent to effectively destroy the structure of the complexed nickel in the wastewater and release free nickel ions, which is helpful for the subsequent nickel recovery process. Then, the UV light is adjusted by the change of pH. Initially, a relatively high intensity UV light (20 to 25 μmol·m-2·s-1) is used to accelerate the decomplexing reaction, so that the pH change rate increases to 0.05 or above, which indicates that the stability of the complex is quickly destroyed and the nickel ions are released, thereby improving the decomplexing efficiency. When the pH change rate reaches or exceeds 0.05, the UV light intensity is reduced, which helps to balance the reaction rate and energy consumption and avoid energy consumption caused by excessive light. The increased consumption and possible side reactions, the UV irradiation is stopped when the pH no longer changes, which indicates that the reaction has reached equilibrium. The conditions at this time are conducive to the complete release and selective removal of nickel ions. Nanofiltration can then effectively retain multivalent ions such as nickel ions, and bipolar membrane electrodialysis can utilize its unique ion exchange function to convert hypophosphite and ammonium ions into corresponding acids and bases, respectively, to achieve their effective separation; bipolar membrane electrodialysis is an electrically driven process that does not require the addition of chemical reagents. Compared with traditional chemical precipitation methods, it can save energy and the use of chemical reagents, reduce processing costs, and through bipolar membrane electrodialysis, hypophosphite and ammonium ions can be converted into phosphoric acid and ammonia water, thereby improving the purity of these products and facilitating subsequent recovery and utilization.

[0033] (2) The separation method of the present invention reduces the influence of a small amount of nickel that may remain in the wastewater after nanofiltration by dividing the bipolar membrane electrodialysis process into multiple time periods, that is, by testing the generation rate of ammonia in each time period, when the generation rate changes, it may be affected by nickel; then when the rate decreases, the fluidity of the solution is increased by increasing the temperature, the viscosity is reduced, thereby accelerating the migration of ions and improving the separation efficiency; by reducing the pressure, the boiling point of water can be reduced, which is beneficial to the volatilization and collection of ammonia, and further improving the separation rate of ammonia; increasing the wastewater introduction rate can process more wastewater per unit time, increase the supply of ammonium ions, and promote the generation of ammonia; when the rate increases, continuing to reduce the pressure can maintain the generation rate of ammonia and keep it efficient; but an excessively high ammonia generation rate may increase the burden on the ion exchange membrane and reduce the performance of the membrane. Therefore, by reducing the introduction rate, the workload of the membrane can be reduced, the risk of membrane contamination can be reduced, and the ammonia concentration in the system can be reduced, reducing the influence of gas-liquid equilibrium, which helps ammonia to escape from the wastewater more easily and be captured by the collection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart showing the separation method of the present invention;

[0035] Figure 2 This is a comparison chart of the results of the separation method exploration 2 of the present invention;

[0036] Figure 3 This is a comparison chart of the results of the separation method exploration 3 of the present invention;

[0037] Figure 4 It is a comparison chart of the results of the separation method exploration 4 of the present invention. DETAILED DESCRIPTION

[0038] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0039] Example 1: A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid, such as Figure 1 As shown, the following steps are included:

[0040] S1. Nanofiltration:

[0041] First, the pH of the chemical nickel plating waste liquid is adjusted to 5.5, and then a complex-breaking agent such as sodium ferrate is added at 0.9% of the total volume of the chemical nickel plating waste liquid, and stirred for 20 minutes; when the pH of the chemical nickel plating waste liquid begins to rise, UV light is introduced and stirring is continued until the pH no longer changes;

[0042] The method of introducing UV light is as follows: based on one minute, the pH change rate is less than 0.05, and the intensity of UV light is 23 μmol·m-2 ·s -1 and increased by 4 μmol·m per minute -2 ·s -1 The light intensity was continuously irradiated until the pH change rate was 0.05 ≤ pH, and the intensity of UV light was reduced to 7 μmol·m -2 ·s -1 ;

[0043] Then, the chemical nickel plating wastewater is subjected to nanofiltration separation at 25° C. and 10 MPa using a rolled nanofiltration membrane, wherein the rolled nanofiltration membrane adopts NF90, to obtain nickel-containing wastewater, hypophosphorous acid-containing wastewater and ammonia-containing wastewater;

[0044] S2, Bipolar membrane electrodialysis:

[0045] The arrangement of the bipolar membrane electrodialysis system is set as follows: the anode, the first bipolar membrane, the anion membrane, the cationic membrane, the second bipolar membrane, and the cathode are arranged in sequence, the area between the first bipolar membrane and the anion membrane is the acid chamber, the area between the cationic membrane and the second bipolar membrane is the alkali chamber, and the area between the anion membrane and the cationic membrane is the desalination chamber; the anion membrane adopts FAA-PK-130, the cationic membrane adopts FKB-PK-130, and the first bipolar membrane and the second bipolar membrane both adopt BPM-6012-50;

[0046] The wastewater containing hypophosphorous acid and ammonia is passed into the desalination chamber, and deionized water is added to both the acid chamber and the alkali chamber, and the volume ratio of the deionized water in the acid chamber to the alkali chamber is 1:2.5. The voltage of the bipolar membrane electrodialysis is 20V and the current density is 20A / m 2 , hypophosphite ions enter the acid chamber, and ammonium ions enter the base chamber, further obtaining hypophosphorous acid solution and ammonia gas, until ammonia gas is no longer generated and bipolar membrane electrodialysis is completed, thereby achieving separation of hypophosphorous acid and ammonia;

[0047] The ammonia gas is recovered, and the method for recovering the ammonia gas is: a hydrochloric acid solution with a concentration of 300g / L is used to absorb the ammonia gas to obtain ammonium chloride, and the recovery is completed.

[0048] Example 2: This example is different from Example 1 in that the pH of the chemical nickel plating waste liquid is first adjusted to 6, and then a complex breaking agent accounting for 0.8% of the total volume of the chemical nickel plating waste liquid is added and stirred for 15 minutes.

[0049] Example 3: This example is different from Example 1 in that the pH of the chemical nickel plating waste liquid is first adjusted to 5, and then a decomplexing agent accounting for 1% of the total volume of the chemical nickel plating waste liquid is added and stirred for 25 minutes.

[0050] Example 4: This example differs from Example 1 in that the pH change rate is less than 0.05 based on one minute, and the intensity of UV light is 20 μmol·m -2 ·s -1 and increased by 3 μmol·m per minute -2 ·s -1 The light intensity was continuously irradiated until the pH change rate was 0.05 ≤ pH, and the intensity of UV light was reduced to 10 μmol·m -2 ·s -1 .

[0051] Example 5: This example differs from Example 1 in that the pH change rate is less than 0.05 based on one minute, and the intensity of UV light is 25 μmol·m -2 ·s -1 and increase by 5 μmol·m per minute -2 ·s -1 The light intensity was continuously irradiated until the pH change rate was 0.05 ≤ pH, and the intensity of UV light was reduced to 5 μmol·m -2 ·s -1 .

[0052] Example 6: This example is different from Example 1 in that the chemical nickel plating wastewater is nanofiltered and separated at 20°C and 5MPa using a rolled nanofiltration membrane, and the rolled nanofiltration membrane uses DK8040F-30P.

[0053] Example 7: This example is different from Example 1 in that the chemical nickel plating wastewater is nanofiltered and separated at 30°C and 15MPa using a rolled nanofiltration membrane, and the rolled nanofiltration membrane is TM620N-400.

[0054] Example 8: This example is different from Example 1 in that the volume ratio of deionized water in the acid chamber and the base chamber is 1:2, the anion membrane uses AMI-7001S, and the cationic membrane uses FKB-PK-130.

[0055] Example 9: This example is different from Example 1 in that the volume ratio of deionized water in the acid chamber and the base chamber is 1:3, the anion membrane uses FAA-PK-130, and the cationic membrane uses FKL-PK-130.

[0056] Example 10: This example is different from Example 1 in that the voltage of the bipolar membrane electrodialysis is 10V and the current density is 15A / m 2 The first bipolar membrane and the second bipolar membrane are both made of BMP-200.

[0057] Example 11: This example is different from Example 1 in that the voltage of the bipolar membrane electrodialysis is 30V and the current density is 25A / m 2 The first bipolar membrane and the second bipolar membrane are both made of JED-6012-40.

[0058] Example 12: This example is different from Example 1 in that the total time T for passing the wastewater containing hypophosphorous acid and ammonia into the desalination chamber is divided into a plurality of time periods of equal length t1, t2, t3, ...t n , n = 9; the T value is 36min, the t1....t n The value of is 4min, and the ammonia generation rate V in the alkali chamber is detected in each time period. t ; In the first time period t1, the introduction rate of the wastewater containing hypophosphorous acid and ammonia is 5L / min, the temperature in the alkali chamber is 23°C, and the pressure in the alkali chamber is 7.5MPa;

[0059] When V t-1 -V t When ≤0, compared with the previous time period, the temperature in the alkali chamber is increased by 1.5 times, the pressure in the alkali chamber is reduced by 55%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is increased by 17.5%;

[0060] When 0<V t-1 -V t When compared with the previous time period, the temperature in the alkali chamber is kept unchanged, the pressure in the alkali chamber is reduced by 15%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is reduced by 7.5%.

[0061] Embodiment 13: This embodiment differs from Embodiment 12 in that the T value is 30 min, and the t1..t n The value of is 3min.

[0062] Example 14: This example is different from Example 12 in that the T value is 45 min, and the t1..t n The value of is 5min.

[0063] Example 15: This example is different from Example 12 in that the introduction rate of the wastewater containing hypophosphorous acid and ammonia in the first time period t1 is 4 L / min, the temperature in the alkali chamber is 20° C., and the pressure in the alkali chamber is 10 MPa.

[0064] Example 16: This example is different from Example 12 in that the introduction rate of the wastewater containing hypophosphorous acid and ammonia in the first time period t1 is 6 L / min, the temperature in the alkali chamber is 25° C., and the pressure in the alkali chamber is 5 MPa.

[0065] Embodiment 17: This embodiment differs from Embodiment 12 in that when V t-1 -V t ≤0, compared with the previous time period, the temperature in the alkali chamber is increased by 1.4 times, the pressure in the alkali chamber is reduced by 50%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is increased by 15%.

[0066] Embodiment 18: This embodiment differs from Embodiment 12 in that when V t-1 -V t ≤0, compared with the previous time period, the temperature in the alkali chamber is increased by 1.6 times, the pressure in the alkali chamber is reduced by 60%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is increased by 20%.

[0067] Embodiment 19: This embodiment differs from Embodiment 12 in that when 0<V t-1 -V t When compared with the previous time period, the temperature in the alkali chamber is kept unchanged, the pressure in the alkali chamber is reduced by 10%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is reduced by 5%.

[0068] Embodiment 20: This embodiment differs from Embodiment 12 in that when 0<V t-1 -V t When compared with the previous time period, the temperature in the alkali chamber is kept unchanged, the pressure in the alkali chamber is reduced by 20%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is reduced by 10%.

[0069] Embodiment 21: This embodiment differs from Embodiment 12 in that when V t-1 -V t ≤-20%~-30%V t When the deionized water in the alkali chamber is firstly subjected to plasma activation treatment to obtain plasma activated water, and the turbulence intensity of the plasma activated water is set to 5.5%; wherein the plasma activation treatment time is 1.5 min, and the power is 650 W;

[0070] When -20%~-30%V t <V t-1 -V t ≤0, firstly, the deionized water in the alkali chamber is subjected to plasma activation treatment to obtain plasma activated water, and the turbulence intensity of the plasma activated water is set to 2.5%; wherein, the plasma activation treatment time is 0.8min, and the power is 500W;

[0071] The plasma activation treatment method is: spraying plasma prepared by a low-temperature plasma generator into deionized water in an alkali chamber.

[0072] Embodiment 22: This embodiment differs from Embodiment 21 in that when Vt-1 -V t ≤-20%~-30%V t The turbulence intensity of plasma activated water is set to 5%; wherein, the plasma activation treatment time is 1 min, and the power is 600 W.

[0073] Embodiment 23: This embodiment differs from Embodiment 21 in that when V t-1 -V t ≤-20%~-30%V t The turbulence intensity of the plasma activated water was set to 6%; the plasma activation treatment time was 2 min and the power was 700 W.

[0074] Example 24: This example is different from Example 21 in that when -20% to -30% V t <V t-1 -V t When ≤0, the turbulence intensity of plasma activated water is set to 2%; wherein, the plasma activation treatment time is 0.5min, and the power is 450W.

[0075] Example 25: This example is different from Example 21 in that when -20% to -30% V t <V t-1 -V t When ≤0, the turbulence intensity of plasma activated water is set to 3%; wherein, the plasma activation treatment time is 1 min, and the power is 550W.

[0076] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0077] In order to illustrate the advantages of the separation method of the present invention, the concentrations of nickel, hypophosphorous acid and ammonia before wastewater separation were tested and compared with the concentrations of nickel, hypophosphorous acid and ammonia in the wastewater after nanofiltration and bipolar membrane electrodialysis to obtain the separation rate of nickel, hypophosphorous acid and ammonia as the performance data of the separation method of the present invention.

[0078] 1. Investigate the effects of decomposition treatment and nanofiltration parameters on nickel separation rate.

[0079] Table 1 Separation rate of nickel in Examples 1 to 7

[0080] Group Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Separation rate / % 99.98 99.86 99.92 99.78 99.89 99.91 99.93

[0081] From the data in Table 1, it can be seen that the parameters of the acidification decomposition treatment are too small or too large, the change of UV light intensity is too small or too large, and the nanofiltration parameters are too small or too large, which will reduce the separation rate of nickel. It can be seen that the separation rate of nickel after decomposition treatment and then nanofiltration is higher, and the separation rate is stable at more than 99.75%.

[0082] 2. Investigate the influence of bipolar membrane electrodialysis parameters on the separation rate of hypophosphorous acid and ammonia.

[0083] Depend on Figure 2 The results show that, compared with Examples 1 to 11, too small or too large volume of deionized water in the acid chamber, too small or too large voltage and current of bipolar membrane electrodialysis will reduce the separation rate of hypophosphorous acid and ammonia. In comprehensive comparison, the parameter effect of Example 1 is relatively better.

[0084] 3. Investigate the effect of the treatment parameters of the alkali chamber on the separation rate of ammonia in bipolar membrane electrodialysis.

[0085] The difference between Comparative Example 1 and Example 12 is that the feeding rate in each time period remains unchanged;

[0086] The difference between Comparative Example 2 and Example 12 is that when 0<V t-1 -V t When compared with the previous time period, the temperature and pressure in the alkali chamber are kept unchanged;

[0087] Depend on Figure 3 The results show that, by comparing Examples 1, 12 to 20 and Control Examples 1 to 2, the temperature and pressure of the alkali chamber and other parameters are adjusted accordingly according to the change of the ammonia generation rate, which significantly improves the separation rate of ammonia; By comparing Examples 12 to 20 and Control Examples 1 to 2, it can be seen that Control Example 1 lacks the flexibility of the introduction rate, and Control Example 2 lacks the flexibility of the parameters after the ammonia generation rate is increased, and the improvement of the ammonia separation rate is reduced compared with Examples 12 to 20. Therefore, the regular changes in Example 8 have a beneficial effect on improving the separation rate of ammonia;

[0088] Compared with Examples 12 to 20, too few or too many time periods, too small or too large parameters in the first time period, too small or too large parameter adjustment range after the ammonia production rate is reduced, and too small or too large parameter adjustment range after the ammonia production rate is increased will all reduce the effect of improving the ammonia separation rate. Therefore, in comprehensive comparison, the parameter effect of Example 8 is relatively better.

[0089] 4. To further explore the effect of the treatment parameters of the alkali chamber on the ammonia separation rate when the ammonia production rate decreases in bipolar membrane electrodialysis.

[0090] Depend on Figure 4 The results show that, compared with Examples 12 and 21 to 25, when the ammonia generation rate is reduced, the ion activation of the deionized water in the alkali chamber can further improve the separation rate of ammonia;

[0091] Comparing Examples 21 to 25, when the ammonia generation rate is reduced more, the plasma activation parameters are too small or too large, and when the ammonia generation rate is reduced less, the plasma activation parameters are too small or too large, both of which will reduce the ammonia separation rate. Therefore, in comprehensive comparison, the parameter effect of Example 21 is relatively better.

Claims

1. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid, characterized in that: The following steps are involved: S1. Nanofiltration: First, the pH of the chemical nickel plating waste liquid is adjusted to 5-6, and then a decomplexing agent accounting for 0.8-1% of the total volume of the chemical nickel plating waste liquid is added, and stirred for 15-25 minutes; when the pH of the chemical nickel plating waste liquid begins to increase, UV light is introduced and stirring is continued until the pH no longer changes; The method of introducing UV light is as follows: based on one minute, the pH change rate is less than 0.05, and the intensity of UV light is 20-25 μmol·m -2 ·s -1 The increase was 3-5 μmol·m per minute. -2 ·s -1 The light intensity was continuously irradiated until the pH change rate was 0.05 ≤ and the intensity of UV light was reduced to 5-10 μmol·m -2 ·s -1 ; Then, the chemical nickel plating wastewater is subjected to nanofiltration separation at 20-30° C. and 5-15 MPa using a rolled nanofiltration membrane to obtain nickel-containing wastewater, hypophosphorous acid-containing wastewater and ammonia-containing wastewater; S2, Bipolar membrane electrodialysis: The arrangement of the bipolar membrane electrodialysis system is as follows: the anode, the first bipolar membrane, the anion membrane, the cationic membrane, the second bipolar membrane, and the cathode are arranged in sequence, the area between the first bipolar membrane and the anion membrane is the acid chamber, the area between the cationic membrane and the second bipolar membrane is the alkali chamber, and the area between the anion membrane and the cationic membrane is the desalination chamber; The wastewater containing hypophosphorous acid and ammonia is passed into the desalination chamber, and deionized water is added to both the acid chamber and the alkali chamber, and the volume ratio of the deionized water in the acid chamber to the alkali chamber is 1:2-3, wherein the voltage of the bipolar membrane electrodialysis is 10-30V, and the current density is 15-25A / m 2 , hypophosphite ions enter the acid chamber, and ammonium ions enter the base chamber, further obtaining hypophosphorous acid solution and ammonia gas, until ammonia gas is no longer generated and bipolar membrane electrodialysis is completed, thereby achieving separation of hypophosphorous acid and ammonia.

2. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 1, characterized in that: The rolled nanofiltration membrane adopts one of NF90, DK8040F-30P and TM620N-400.

3. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 1, characterized in that: The anion membrane is FAA-PK-130 or AMI-7001S, and the cationic membrane is FKB-PK-130 or FKL-PK130.

4. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 1, characterized in that: The first bipolar membrane and the second bipolar membrane are both made of one of BPM-6012-50, BMP-200 and JED-6012-40.

5. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 1, characterized in that: The total time T of passing the wastewater containing hypophosphorous acid and ammonia into the desalination chamber is divided into a plurality of time periods t1, t2, t3, ...t n , n = 6 to 15; the T value is 30 to 45 min, the t1....t n The value of is 3 to 5 minutes, and each time period t1....t n The generation rate of ammonia in the inner alkali chamber V t ; Among them, in the first time period t1, the introduction rate of the wastewater containing hypophosphorous acid and ammonia is 4-6L / min, the temperature in the alkali chamber is 20-25°C, and the pressure in the alkali chamber is 5-10MPa; When V t-1 -V t ≤0, compared with the previous time period, the temperature in the alkali chamber is increased by 1.4 to 1.6 times, the pressure in the alkali chamber is reduced by 50 to 60%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is increased by 15 to 20%; When 0<V t-1 -V t When compared with the previous time period, the temperature in the alkali chamber is kept unchanged, the pressure in the alkali chamber is reduced by 10-20%, and the introduction rate of the wastewater containing hypophosphorous acid and ammonia is reduced by 5-10%.

6. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 5, characterized in that: When V t-1 -V t ≤-20%~-30%V t When the deionized water in the alkali chamber is firstly subjected to plasma activation treatment to obtain plasma activated water, and the turbulence intensity of the plasma activated water is set to 5-6%; wherein the plasma activation treatment time is 1-2 minutes, and the power is 600-700W; When -20%~-30%V t <V t-1 -V t ≤0, firstly perform plasma activation treatment on the deionized water in the alkali chamber to obtain plasma activated water, and set the turbulence intensity of the plasma activated water to 2-3%; wherein, the plasma activation treatment time is 0.5-1min, and the power is 450-550W.

7. A method for efficiently separating nickel, hypophosphorous acid and ammonia from chemical nickel plating waste liquid as claimed in claim 6, characterized in that: The plasma activation treatment method is: spraying plasma prepared by a low-temperature plasma generator into deionized water in an alkali chamber.

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