A sodium ion exchange column regeneration method

Abstract

The present invention belongs to the field of ion exchange columns, and in particular relates to a sodium ion exchange column regeneration method, comprising the steps of top washing, backwashing, pickling, water deacidification, alkaline washing, and water dealkalization. The top washing, pickling, and water deacidification steps utilize a top-in, bottom-out cyclic flushing method, while the backwashing, alkaline washing, and water dealkalization steps utilize a bottom-in, top-out cyclic flushing method. The method of the present invention can effectively remove calcium and magnesium ions adsorbed on the exchange resin, allowing the exchange capacity and ability of the regenerated ion exchange resin to remain at a high level, thereby extending the service life of the exchange column.

Description

Technical Field

[0001] The invention belongs to the field of ion exchange columns, and in particular relates to a sodium ion exchange column regeneration method. Background Art

[0002] An ion exchange column is a tool used to separate and purify compounds. It uses the ion exchange resin filled in the column to selectively adsorb and release ions in the sample.

[0003] Lithium-containing solution calcium and magnesium removal ion exchange columns utilize ion exchange resins to selectively adsorb and release calcium and magnesium ions from the solution. In water treatment, calcium and magnesium ions are common scaling components, forming insoluble calcium and magnesium carbonate precipitates in the solution, degrading water quality.

[0004] Sodium ion exchange resin is a resin formed by converting a strongly acidic cationic resin into NaCl. Sodium ion exchange resin contains a large number of strongly acidic functional groups, which readily dissociate into hydrogen in water, forming a strong acid. Sodium ion exchange columns can effectively remove calcium and magnesium ions from water. The calcium and magnesium ions that contribute to water hardness are exchanged with the ion exchange resin in the column. Through the sodium cation exchange resin, the calcium and magnesium ions in the water are exchanged for sodium ions, making it less likely to form carbonate and sulfate scale, thereby improving water quality. However, after prolonged use, high-valent metal ions and various high-molecular-weight organic compounds form insoluble deposits within the resin, blocking the ion exchange channels. However, replacing new ion exchange resins is relatively expensive, so regenerating ion exchange resins has become a new research and development motivation.

[0005] In the traditional regeneration method, deionized water is generally used to replace the chelating cation exchange resin column, and then it is acid-washed with hydrochloric acid solution in sequence to elute the adsorbed calcium and magnesium ions, and the residual acid is washed with deionized water. The resin is alkaline-washed with sodium hydroxide solution and the residual alkali is washed with deionized water to obtain a recyclable chelating cation exchange resin column. However, the washing process does not include forward washing and backwashing processes, the regeneration is incomplete, and the amount of sodium hydroxide used is large.

[0006] The specification of Chinese invention CN200710133332.7 discloses a method for regenerating an ion exchange resin. The method comprises the steps of passing a decomposing solution through an ion exchange column filled with the ion exchange resin to remove impurity ions adsorbed or firmly bound to the resin, and passing a regeneration solution through the ion exchange column in a countercurrent flow to restore the ion exchange capacity of the ion exchange resin. The decomposing solution and the regeneration solution are passed into the ion exchange column sequentially using a cocurrent flow and a countercurrent flow, respectively. Ion exchange resin regenerated using this combined cocurrent and countercurrent flow method can effectively disperse and evenly distribute within the ion exchange column, thereby improving the column efficiency of the ion exchange column, reducing energy consumption and production costs, and benefiting the environment. This patent mentions the combined cocurrent and countercurrent flow method for regeneration, but the problem is that regeneration is incomplete and may not be suitable for regeneration of sodium ion exchange resins. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a sodium ion exchange column regeneration method, which can effectively remove the calcium and magnesium ions adsorbed on the exchange resin, so that the exchange capacity and ability of the regenerated ion exchange resin can still be maintained at a high level, thereby extending the service life of the exchange column.

[0008] A sodium ion exchange column regeneration method in the present invention for solving the above technical problems comprises the following steps:

[0009] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column;

[0010] (2) Backwashing: The resin obtained in step (1) is circulated and flushed from the bottom of the exchange column using regeneration liquid to loosen the resin bed; the pressurized resin bed of the top wash exchange column is squeezed together, and the backwashing disperses the bed and displaces the resin, which is more conducive to the rear-end acid washing, and a small amount of broken resin will be discharged with the water flow.

[0011] (3) Acid washing: The resin obtained in step (2) is washed by circulating liquid from the top of the exchange column using an inorganic acid; acid washing has a better acidification effect on the loose bed.

[0012] (4) Water deacidification: Pure water is used to circulate the resin obtained in step (3) from the top of the exchange column to remove residual inorganic acid in the resin;

[0013] (5) Alkali washing: using sodium hydroxide solution to circulate the resin obtained in step (4) from the bottom of the exchange column to wash the resin;

[0014] (6) De-alkali: The resin obtained in step (5) is rinsed with pure water from the bottom of the exchange column, and the rinse water is then drained to obtain a regenerated sodium ion exchange resin. After regeneration, the resin regains its adsorption capacity and can periodically adsorb calcium and magnesium ions.

[0015] The sodium ion exchange resin of the present invention is a chelate ion exchange resin with a macroporous structure of styrene-divinylbenzene copolymer spheres having an iminodiacetic acid group [-N-(CH2COOH)2] on the benzene ring, which reduces the calcium and magnesium ion contents in the lithium-containing solution.

[0016] In the present invention, the calcium content of the lithium-containing solution exiting the ion exchange column must be controlled to <0.05g / l and the magnesium content to <0.01g / l. When the calcium content of the outlet solution approaches 0.05g / l, the ion exchange column needs to be regenerated. The purpose of regeneration is to reduce sodium ions, remove calcium and magnesium, restore the resin to normal state, and ensure that the outlet solution meets the index standards. The reaction principle is as follows:

[0017] Pickling process: R2-Ca+2HCl=2R-H+CaCl2;

[0018] R2-Mg+2HCl=2R-H+MgCl2;

[0019] R-Li+HCl=R-H+LiCl;

[0020] Alkali washing process: R-H+NaOH=R-Na+H2O;

[0021] Exchange process: 2R-Na+Ca 2+ =R2-Ca+2Na + ;

[0022] 2R-Na+Mg 2+ =R2-Mg+2Na + ;

[0023] R-Na+Li + =R-Li+Na + .

[0024] The sodium ion exchange column regeneration method of the present invention first rinses the ion exchange column resin with pure water until the water outlet is clear. The ion exchange resin is then circulated and rinsed with a regeneration solution. The regeneration solution shrinks the ion exchange resin, reducing the osmotic pressure of calcium and magnesium ions in the solution surrounding the ion exchange resin particles into the resin particles, allowing organic matter bound to the resin skeleton by intermolecular forces to be easily "shed" by the regeneration solution. The ion exchange resin is then circulated and rinsed with a mineral acid to remove the calcium and magnesium ions adsorbed on the ion exchange resin. Regeneration is then completed by circulated and rinsed with a sodium hydroxide solution.

[0025] The volume of the ion exchange column in the present invention is 15m 3 , sodium ion exchange resin occupies 2 / 3 of the ion exchange column, about 10m 3 .

[0026] The pure water flushing flow rate in step (1) is 20-30m3 / h, adopt the top-in and bottom-out method to circulate and flush for 1-2h.

[0027] The backwash flow rate of the regeneration liquid in step (2) is 10-20m 3 / h, adopt bottom-in-top-out method to circulate and flush for 2-4h.

[0028] The inorganic acid flushing flow rate in step (3) is 10-20m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 2-3h.

[0029] The pure water flushing flow rate in step (4) is 20-30m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 2-3h.

[0030] The sodium hydroxide flushing flow rate in step (5) is 10-20m 3 / h, adopt bottom-in-top-out method to circulate and flush for 5-8h.

[0031] The pure water flushing flow rate in step (6) is 20-30m 3 / h, adopt bottom-in-top-out method to circulate and flush for 2-3h.

[0032] The regeneration liquid in step (2) is sodium chloride soft water salt with a content of 99.8% and a concentration of 5%-12%. The mass concentration of the regeneration liquid solution in the optimized solution is 5%-15%.

[0033] The inorganic acid in step (3) is hydrochloric acid with a mass concentration of 5%-15%.

[0034] The concentration of sodium hydroxide in step (5) is 5%-15%.

[0035] The method of the present invention can effectively remove organic matter and calcium and magnesium ions adsorbed on the sodium ion exchange resin, has a relatively good elution effect, and the skeleton of the sodium ion exchange resin itself and the functional groups located thereon will not be damaged, thereby maximally restoring the exchange capacity and ability of the calcium and magnesium ion absorption resin and extending the service life of the exchange column.

[0036] In the present invention, top washing, acid washing, and water deacidification constitute forward washing, while backwashing, alkali washing, and water dealkaliification constitute reverse washing. Multiple forward and reverse washing steps achieve a complete regeneration effect. In normal production, an ion exchange column can be used for 30 hours. After the resin is regenerated using the method of the present invention, the ion exchange column can be used for 30-60 hours, extending its service life. The method of the present invention uses less energy and reduces regeneration time to restore the resin to its original state. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flow chart of the regeneration method in the present invention DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to specific embodiments:

[0039] Example 1

[0040] Sodium ion exchange column regeneration method: top washing, acid washing and water deacidification steps adopt top-in-bottom-out circulation flushing, backwashing, alkaline washing and water dealkali steps adopt bottom-in-top-out circulation flushing. The volume of the ion exchange column is 15m 3 , sodium ion exchange resin occupies 2 / 3 of the ion exchange column, about 10m 3 The specific steps are as follows:

[0041] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column; the pure water flushing flow rate is 30m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 1.5h.

[0042] (2) Backwash: Use regeneration liquid to circulate the resin obtained in step (1) from the bottom of the exchange column to flush the resin and loosen the resin bed; the regeneration liquid is 99.8% sodium chloride soft water salt with a concentration of 12%. The regeneration liquid backwash flow rate is 20m 3 / h, and circulate the flushing for 4 hours in a bottom-in and top-out manner.

[0043] (3) Acid washing: The resin obtained in step (2) is washed by circulating the resin from the top of the exchange column with hydrochloric acid; the hydrochloric acid is 8% by mass. The flow rate of the hydrochloric acid washing is 20m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 2.5h.

[0044] (4) Water deacidification: Use pure water to circulate the resin obtained in step (3) from the top of the exchange column to remove the residual inorganic acid in the resin; the pure water flushing flow rate is 30m 3 / h, and circulate the flushing for 3 hours in a top-in and bottom-out manner.

[0045] (5) Alkali washing: Use sodium hydroxide solution to wash the resin obtained in step (4) from the bottom of the exchange column; the mass concentration of sodium hydroxide is 5%. The washing flow rate of sodium hydroxide is 20m 3 / h, and circulate the flushing for 7 hours in a bottom-in and top-out manner.

[0046] If flushing is done from top to bottom, the alkaline cleaning effect is poor, and the bed layers will be squeezed together, which is not conducive to loose bed alkaline cleaning. Because the ion exchange resin regeneration methods of the present invention include bottom-in-top-out regeneration and top-in-bottom-out regeneration, and the regeneration liquid enters the exchanger from the top in the opposite direction to the raw water, countercurrent regeneration can greatly improve the utilization rate of the regeneration agent, reduce the consumption of the regeneration agent, and improve the water quality. This not only helps to reduce the consumption of cleaning water, but also reduces the discharge volume and concentration of the regeneration waste liquid.

[0047] In top-in, bottom-out regeneration, the regeneration liquid flows through the exchange layer in the same direction as the raw water. The advantage of top-in, bottom-out regeneration is that the ion exchange equipment is streamlined and relatively reliable. After regeneration, the regeneration degree at the bottom is the lowest. To improve the working exchange capacity and effluent quality, the consumption of regeneration agent will inevitably increase. Moreover, if the raw water quality components are excessively affected, the exchange capacity cannot be fully utilized. When the regeneration liquid flows to the exchange layer, it first comes into contact with the ions at the top of the exchange layer that have expired and have been converted from the top exchange layer. This affects the regeneration degree at the bottom of the exchange layer (regeneration degree refers to the ratio of the total exchange capacity to the amount of regenerated ions in the ion exchange layer). This can easily lead to a decrease in treated water quality and increase the consumption of regeneration agent.

[0048] (6) Water de-alkali: Use pure water to flush the resin obtained in step (5) from the bottom of the exchange column, and then drain the washing water to obtain the regenerated sodium ion exchange resin. The pure water flushing flow rate is 30m 3 / h, and circulate the flushing for 3 hours in a bottom-in and top-out manner.

[0049] Before regeneration, the calcium content in the solution was 0.048 g / L and the magnesium content was 0.01 g / L. After regeneration, the calcium content in the solution was 0.005 g / L and the magnesium content was 0.003 g / L. The regenerated ion exchange column can be used for about 55 hours.

[0050] The sodium ion exchange column regeneration method of the present invention uses a regeneration liquid to remove organic impurities adsorbed on the sodium ion exchange resin, and uses an inorganic acid to remove calcium and magnesium ions adsorbed on the sodium ion exchange resin. The organic matter and calcium and magnesium ions adsorbed on the sodium ion exchange resin can be effectively removed, the elution effect is relatively good, and the skeleton of the sodium ion exchange resin itself and the functional groups located thereon are not damaged. The exchange capacity and ability of the sodium ion exchange resin are restored to the maximum extent, and the service life of the exchange column is extended.

[0051] Example 2

[0052] The regeneration method of sodium ion exchange resin is as follows:

[0053] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column at a flow rate of 20m 3 / h, the circulating flushing time is 1h until the water is clear;

[0054] (2) Backwash: Use 5% regeneration liquid to circulate the resin obtained in step (1) from the bottom of the exchange column to flush the resin. The regeneration liquid flow rate is 10m 3 / h, the circulating flushing time is 3h, to remove the organic impurities adsorbed on the sodium ion exchange resin;

[0055] (3) Acid washing: Use 5% hydrochloric acid to wash the resin obtained in step (2) from the top of the exchange column, and the hydrochloric acid flow rate is 10m 3 / h, the circulating flushing time is 2h, to remove the calcium and magnesium ions adsorbed on the sodium ion resin;

[0056] (4) Water deacidification: Use pure water to circulate the resin obtained in step (3) from the top of the exchange column to remove the residual inorganic acid in the resin. The flow rate is 20m 3 / h, the cycle flushing time is 2h;

[0057] (5) Alkali washing: Use 5% sodium hydroxide to wash the resin obtained in step (4) from the bottom of the exchange column, with a flow rate of 10m 3 / h, the cycle flushing time is 5h;

[0058] (6) Water dealkali: Use pure water to circulate the resin obtained in step (5) from the bottom of the exchange column to flush the resin at a flow rate of 20m 3 / h, and the circulating flushing time is 2h. Then the washing water is drained to complete the regeneration of the sodium ion exchange resin.

[0059] Before regeneration, the calcium content in the solution was 0.045 g / L and the magnesium content was 0.008 g / L. After regeneration, the calcium content in the solution was 0.004 g / L and the magnesium content was 0.002 g / L. The regenerated ion exchange column can be used for about 40 hours.

[0060] Example 3

[0061] The regeneration method of sodium ion exchange resin comprises the following steps:

[0062] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column at a flow rate of 25m 3 / h, the circulating flushing time is 1h until the water is clear;

[0063] (2) Backwash: Use 5% regeneration liquid to circulate the resin obtained in step (1) from the bottom of the exchange column to flush the resin. The regeneration liquid flow rate is 15m3 / h, the circulating flushing time is 3h, to remove the organic impurities adsorbed on the sodium ion exchange resin;

[0064] (3) Acid washing: Use 5% hydrochloric acid to wash the resin obtained in step (2) from the top of the exchange column, and the hydrochloric acid flow rate is 15m 3 / h, the circulating flushing time is 2h, to remove the calcium and magnesium ions adsorbed on the sodium ion resin;

[0065] (4) Water deacidification: Use pure water to circulate the resin obtained in step (3) from the top of the exchange column to remove the residual inorganic acid in the resin. The flow rate is 25m 3 / h, the cycle flushing time is 2h;

[0066] (5) Alkali washing: Use 5% sodium hydroxide to wash the resin obtained in step (4) from the bottom of the exchange column, with a flow rate of 15m 3 / h, the cycle flushing time is 5h;

[0067] (6) Water dealkali: Use pure water to circulate the resin obtained in step (5) from the bottom of the exchange column to flush the resin at a flow rate of 25m 3 / h, and the circulating flushing time is 2h. Then the washing water is drained to complete the regeneration of the sodium ion exchange resin.

[0068] Before regeneration, the calcium content in the solution was 0.049 g / L and the magnesium content was 0.007 g / L. After regeneration, the calcium content in the solution was 0.005 g / L and the magnesium content was 0.001 g / L. The regenerated ion exchange column can be used for about 55 hours.

[0069] Example 4

[0070] The regeneration method of sodium ion exchange resin comprises the following steps:

[0071] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column at a flow rate of 20m 3 / h, the circulating flushing time is 2h until the water is clear;

[0072] (2) Backwash: Use 10% regeneration liquid to circulate the resin obtained in step (1) from the bottom of the exchange column to flush the resin. The regeneration liquid flow rate is 10m 3 / h, the circulating flushing time is 3h, to remove the organic impurities adsorbed on the sodium ion exchange resin;

[0073] (3) Acid washing: Use 10% hydrochloric acid to wash the resin obtained in step (2) from the top of the exchange column, and the hydrochloric acid flow rate is 10m 3 / h, the circulating flushing time is 2h, to remove the calcium and magnesium ions adsorbed on the sodium ion resin;

[0074] (4) Water deacidification: Use pure water to circulate the resin obtained in step (3) from the top of the exchange column to remove the residual inorganic acid in the resin. The flow rate is 25m 3 / h, the cycle flushing time is 2h;

[0075] (5) Alkali washing: Use 10% sodium hydroxide to wash the resin obtained in step (4) from the bottom of the exchange column, with a flow rate of 10m 3 / h, the cycle flushing time is 6h;

[0076] (6) Water dealkali: Use pure water to circulate the resin obtained in step (5) from the bottom of the exchange column to flush the resin at a flow rate of 20m 3 / h, and the circulating flushing time is 2h. Then the washing water is drained to complete the regeneration of the sodium ion exchange resin.

[0077] Before regeneration, the calcium content in the solution was 0.045 g / L and the magnesium content was 0.010 g / L. After regeneration, the calcium content in the solution was 0.006 g / L and the magnesium content was 0.002 g / L. The regenerated ion exchange column can be used for about 60 hours.

[0078] Example 5

[0079] The regeneration method of sodium ion exchange resin comprises the following steps:

[0080] (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column at a flow rate of 20m 3 / h, the circulating flushing time is 1.5h until the water is clear;

[0081] (2) Backwash: Use 15% regeneration liquid to circulate the resin obtained in step (1) from the bottom of the exchange column to flush the resin. The regeneration liquid flow rate is 10m 3 / h, the circulation flushing time is 2h, to remove the organic impurities adsorbed on the sodium ion exchange resin; the higher the concentration, the shorter the flushing time.

[0082] (3) Acid washing: Use 15% hydrochloric acid to wash the resin obtained in step (2) from the top of the exchange column, and the hydrochloric acid flow rate is 10m 3 / h, the circulating flushing time is 3h, to remove the calcium and magnesium ions adsorbed on the sodium ion resin;

[0083] (4) Water deacidification: Use pure water to circulate the resin obtained in step (3) from the top of the exchange column to remove the residual inorganic acid in the resin. The flow rate is 25m 3 / h, the cycle flushing time is 2h;

[0084] (5) Alkali washing: Use 15% sodium hydroxide to wash the resin obtained in step (4) from the bottom of the exchange column, with a flow rate of 10m 3 / h, the cycle flushing time is 8h;

[0085] (6) Water dealkali: Use pure water to circulate the resin obtained in step (5) from the bottom of the exchange column to flush the resin at a flow rate of 20m 3 / h, and the circulating flushing time is 2h. Then the washing water is drained to complete the regeneration of the sodium ion exchange resin.

[0086] Before regeneration, the calcium content in the solution was 0.050 g / L and the magnesium content was 0.009 g / L. After regeneration, the calcium content in the solution was 0.002 g / L and the magnesium content was 0.001 g / L. The regenerated ion exchange column can be used for about 60 hours.

[0087] As can be seen from the data in the above examples, the regeneration method of the present invention can effectively remove the calcium and magnesium ions adsorbed on the sodium ion exchange resin, the elution effect is relatively good, and the skeleton of the sodium ion exchange resin itself and the functional groups located thereon are not damaged, thereby maximally restoring the exchange capacity and ability of the calcium and magnesium ion absorption resin, thereby extending the service life of the exchange column.

[0088] During actual regeneration and flushing, be careful not to use too high a flow rate during backwashing, as this can easily flush the resin out of the column. The length of time the column is exchanged after regeneration is related to the amount of reaction. The amount used in each step can be greater than the amount of resin to ensure complete reaction. A higher concentration requires a smaller amount of resin to be used and a larger amount of water to be washed. A reasonable regeneration plan can be adjusted according to actual conditions.

[0089] The above embodiments and test examples are merely examples for clarity of explanation and are not intended to limit the embodiments. Those skilled in the art will appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all embodiments here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A sodium ion exchange column regeneration method, characterized in that: The following steps are involved: (1) Top wash: drain the lithium oxide solution in the ion exchange column and flush the resin with pure water from the top of the exchange column; (2) Backwash: Use regeneration liquid to circulate and flush the resin from the bottom of the exchange column; (3) Acid washing: Use inorganic acid to circulate and flush the resin from the top of the exchange column; (4) Water deacidification: Pure water is introduced from the top of the exchange column to circulate and flush the resin; (5) Alkali washing: Use sodium hydroxide solution to circulate and flush the resin from the bottom of the exchange column; (6) Water dealkali: Use pure water to circulate and flush the resin from the bottom of the exchange column, and drain the washing water to obtain the resin; The regeneration liquid in step (2) is sodium chloride soft water salt, and the mass concentration of the regeneration liquid solution is 5%-15%.

2. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The pure water flushing flow rate in step (1) is 20-30m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 1-2h.

3. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The backwash flow rate of the regeneration liquid in step (2) is 10-20m 3 / h, adopt bottom-in-top-out method to circulate and flush for 2-4h.

4. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The inorganic acid flushing flow rate in step (3) is 10-20m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 2-3h.

5. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The pure water flushing flow rate in step (4) is 20-30m 3 / h, adopt the top-in and bottom-out method to circulate and flush for 2-3h.

6. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The sodium hydroxide flushing flow rate in step (5) is 10-20m 3 / h, adopt bottom-in-top-out method to circulate and flush for 5-8h.

7. A sodium ion exchange column regeneration method according to any one of claims 1 to 6, characterized in that: The pure water flushing flow rate in step (6) is 20-30m 3 / h, adopt bottom-in-top-out method to circulate and flush for 2-3h.

8. A sodium ion exchange column regeneration method according to claim 7, characterized in that: The mass concentration of sodium hydroxide in step (5) is 5%-15%.

9. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The mass concentration of the regeneration solution is 5%-12%.

10. A sodium ion exchange column regeneration method according to claim 1, characterized in that: The inorganic acid in step (3) is hydrochloric acid with a mass concentration of 5%-15%.

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