A method for testing the ratio of anion and cation exchange resins in a mixed bed

Abstract

The invention discloses a method for testing the ratio of anion and cation exchange resins in a mixed bed, the method comprising converting the anion and cation exchange resins in the mixed bed into chloride-type ion exchange resins and cationic ion exchange resins respectively with hydrochloric acid, fully washing with deionized water, and then replacing the chloride ions of the chloride-type ion exchange resin and the hydrogen ions of the cationic ion exchange resin with a sodium nitrate solution to obtain a solution containing chloride ions and hydrogen ions, taking the solution and titrating the hydrogen ions with a sodium hydroxide solution and the chloride ions with a silver nitrate solution, respectively, and calculating the molar ratio of the anion and cation exchange resins in the mixed bed by the molar ratio of chloride ions to hydrogen ions. The method of the invention does not need to separate the anion and cation exchange resins in the mixed bed, and can directly obtain the ratio of the anion and cation exchange resins in the mixed bed by measuring the anion and cation concentrations through transformation and ion replacement. Compared with the existing method, the method is simpler and has higher measurement accuracy.

Description

Technical Field

[0001] The invention belongs to the field of ion exchange resin testing, and in particular relates to a method for testing the ratio of anion and cation exchange resins in a mixed bed. Background Art

[0002] Ion exchange resin is the most common method to remove ionic impurities in water. Mixed bed is a combination of ion exchange resins to obtain the best water quality and is widely used in water treatment. In order to obtain the most economical and effective mixed bed, different proportions of anion and cation exchange resins are required according to different water qualities. The proportion of anion and cation resins used in the mixed bed needs to be determined to determine whether the proportion used is appropriate and meets the requirements.

[0003] At present, the method for testing the ratio of anion and cation exchange resins in a mixed bed is to separate the anion and cation exchange resins by using the density difference of the anion and cation exchange resins, and obtain the anion and cation exchange resins after separation. In order to obtain accurate results, the above separation process usually requires more than 3 times. The volume of the separated anion and cation exchange resins is measured by a measuring cylinder, and then the volume exchange capacity of the anion and cation exchange resins is tested, and finally converted to the exchange capacity ratio of the anion and cation exchange resins in the mixed bed. The above method mainly has the following problems: (1) The anion and cation exchange resins in the mixed bed cannot be completely separated, and the separation needs to be repeated many times to ensure that the anion and cation exchange resins are separated as much as possible so that the test results meet the requirements, resulting in the method being cumbersome to operate and low in accuracy; (2) After the ion exchange resins are separated, the exchange capacity ratio of the anion and cation exchange resins in the mixed bed is not directly obtained. It is necessary to quantify its volume or weight, and then test its corresponding exchange capacity to convert it, and the test method is complicated. Therefore, a simple and accurate method for testing the ratio of anion and cation exchange resins in a mixed bed is urgently needed to solve the above problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a simple and accurate method for testing the ratio of anion and cation exchange resins in a mixed bed.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0006] A method for testing the ratio of anion and cation exchange resins in a mixed bed comprises the following steps:

[0007] (1) converting the anion and cation exchange resins in the mixed bed into chloride-type ion exchange resin and cationic ion exchange resin respectively using hydrochloric acid;

[0008] (2) using deionized water to fully rinse the chloride-type ion exchange resin and the cationic ion exchange resin, and then using sodium nitrate solution to replace the chloride ions of the chloride-type ion exchange resin and the hydrogen ions of the cationic ion exchange resin to obtain a solution containing chloride ions and hydrogen ions;

[0009] (3) A solution containing chloride ions and hydrogen ions is titrated with a sodium hydroxide solution to displace the hydrogen ions, and with a silver nitrate solution to displace the chloride ions, respectively, to obtain the molar concentration of hydrogen ions and the molar concentration of chloride ions, or to obtain the amount of hydrogen ions and the amount of chloride ions. The molar ratio of the anion and cation exchange resins in the mixed bed is equal to the molar ratio of the replaced chloride ions / hydrogen ions, and the molar ratio of the chloride ions to the hydrogen ions is calculated based on the molar ratio of the anion and cation exchange resins in the mixed bed.

[0010] In the above-mentioned test method for the ratio of anion and cation exchange resins in the mixed bed, preferably, in step (3), the hydrogen ions are replaced by titration with sodium hydroxide solution by measuring the molar concentration of hydrogen ions or the amount of hydrogen ions in the solution by titration with sodium hydroxide solution according to the DL / T 502.5 method.

[0011] In the above-mentioned test method for the ratio of anion and cation exchange resins in the mixed bed, preferably, in step (3), the process of replacing chloride ions by titration with silver nitrate solution is: first, a solution containing chloride ions and hydrogen ions is treated with alkali to obtain a neutral solution, and then the molar concentration of chloride ions or the amount of chloride ions in the solution is measured by titration with silver nitrate solution according to the GB / T 15453 method.

[0012] In the above-mentioned test method for the ratio of anion and cation exchange resins in a mixed bed, preferably, in step (1), the mass volume ratio of the anion and cation exchange resin to hydrochloric acid is 10g-20g:1L, and the volume ratio of HCl to water in the hydrochloric acid is 1:8-9.

[0013] In the above-mentioned method for testing the ratio of anion and cation exchange resins in a mixed bed, preferably, in step (2), the desalted water is pure water with a conductivity of less than 0.1 μS / cm.

[0014] In the above-mentioned method for testing the ratio of anion and cation exchange resins in a mixed bed, preferably, in step (2), the sufficient flushing is performed until the pH value of the flushing liquid is 7.

[0015] In the above-mentioned method for testing the ratio of anion and cation exchange resins in a mixed bed, preferably, in step (2), the mass concentration of the sodium nitrate solution is 20 g / L to 25 g / L.

[0016] In the above-mentioned method for testing the ratio of anion and cation exchange resins in the mixed bed, preferably, in step (3), the molar concentration of the sodium hydroxide solution is 0.08 mol / L to 0.12 mol / L, and is calibrated with the reference substance potassium hydrogen phthalate.

[0017] In the above-mentioned method for testing the ratio of anion and cation exchange resins in a mixed bed, preferably, in step (3), the molar concentration of the silver nitrate solution is 0.08 mol / L to 0.12 mol / L, and is calibrated with the reference substance sodium chloride.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The method of the present invention does not need to separate the anion and cation exchange resins in the mixed bed, and the ratio of the anion and cation exchange resins in the mixed bed can be obtained by directly measuring the anion and cation concentrations through transformation and ion replacement. Compared with the existing method, the method is simpler and has higher measurement accuracy. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0021] Embodiment 1:

[0022] A method for testing the ratio of anion and cation exchange resins in a mixed bed of the present invention comprises the following steps:

[0023] (1) Weigh 40.0 g of Dow IRN160 mixed ion exchange resin (i.e., anion and cation exchange resin) and convert the anion and cation exchange resin with 2 L of hydrochloric acid, wherein the volume ratio of HCl to water in the hydrochloric acid is 1:9, so that the anion exchange resin is converted into a chloride-type ion exchange resin and the cation exchange resin is converted into a cationic ion exchange resin.

[0024] (2) The chloride-type ion exchange resin and cationic ion exchange resin after the above conversion are fully rinsed with a large amount of deionized water until the pH of the rinse liquid is 7. The deionized water is pure water with a conductivity of 0.08 μS / cm. Then, 2 L of 20 g / L sodium nitrate solution is passed through a mixed bed to replace the chloride ions in the chloride-type ion exchange resin and the hydrogen ions in the cationic ion exchange resin. 2 L of the replacement liquid is collected to obtain 2 L of a solution containing chloride ions and hydrogen ions.

[0025] (3) Stir the 2 L solution containing chloride ions and hydrogen ions evenly, transfer 100.00 mL of the solution to a volumetric flask, and titrate the hydrogen ion concentration in the solution using a sodium hydroxide solution calibrated to 0.1004 mol / L according to the DL / T 502.5 method, and record the volume of the sodium hydroxide solution consumed as 20.88 mL; wherein the concentration of the sodium hydroxide solution is calibrated using the reference substance potassium hydrogen phthalate.

[0026] Take 200mL of the solution containing chloride ions and hydrogen ions and treat it with sodium hydroxide solution to become a neutral solution. Then transfer 100.00mL of the neutral solution to a volumetric flask. According to the GB / T 15453 method, titrate with a silver nitrate solution calibrated to 0.1012mol / L to measure the chloride ion concentration in the solution. Record the volume of the consumed silver nitrate solution as 41.42mL. The concentration of the silver nitrate solution is calibrated with the reference substance sodium chloride.

[0027] According to the measured amount of hydrogen ion substance and the amount of chloride ion substance (or hydrogen ion molar concentration and chloride ion molar concentration), the molar ratio of anion and cation exchange resins in the mixed bed can be calculated as follows:

[0028]

[0029] Since Dow IRN160 uses the method of non-separation of anion and cation exchange resins to ensure that the anion and cation resins are not separated during resin transportation and operation, the water quality of the mixed bed effluent is better. When using traditional methods for separation, the anion and cation resins cannot be completely separated and the ratio between them cannot be tested.

[0030] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for testing the ratio of anion and cation exchange resins in a mixed bed, characterized in that: The following steps are involved: (1) converting the anion and cation exchange resins in the mixed bed into chloride-type ion exchange resin and cationic ion exchange resin respectively using hydrochloric acid; (2) using deionized water to fully rinse the chloride-type ion exchange resin and the cationic ion exchange resin, and then using sodium nitrate solution to replace the chloride ions of the chloride-type ion exchange resin and the hydrogen ions of the cationic ion exchange resin to obtain a solution containing chloride ions and hydrogen ions; (3) taking a solution containing chloride ions and hydrogen ions and titrating with sodium hydroxide solution to displace hydrogen ions and with silver nitrate solution to displace chloride ions, respectively, to obtain the molar concentration of hydrogen ions and the molar concentration of chloride ions, or to obtain the amount of substance of hydrogen ions and the amount of substance of chloride ions, and calculating the molar ratio of anion and cation exchange resins in the mixed bed according to the molar ratio of anion and cation exchange resins in the mixed bed being equal to the molar ratio of chloride ions / hydrogen ions displaced; In step (1), the mass volume ratio of the anion and cation exchange resin to the hydrochloric acid is 10 g to 20 g: 1 L, and the volume ratio of HCl to water in the hydrochloric acid is 1: 8 to 9; In step (2), the desalted water is pure water with a conductivity of less than 0.1 μS / cm; In step (2), the step of fully rinsing until the pH of the rinsing solution is 7; In step (2), the mass concentration of the sodium nitrate solution is 20 g / L to 25 g / L.

2. The method for testing the ratio of anion and cation exchange resins in a mixed bed according to claim 1, characterized in that: In step (3), the step of replacing hydrogen ions by titration with sodium hydroxide solution is to measure the molar concentration of hydrogen ions or the amount of hydrogen ions in the solution by titration with sodium hydroxide solution according to the DL / T 502.5 method.

3. The method for testing the ratio of anion and cation exchange resins in a mixed bed according to claim 1, characterized in that: In step (3), the process of titrating and replacing chloride ions with silver nitrate solution is as follows: first, a solution containing chloride ions and hydrogen ions is treated with alkali to obtain a neutral solution, and then the molar concentration of chloride ions or the amount of chloride ions in the solution is measured by titrating with silver nitrate solution according to the GB / T 15453 method.

4. The method for testing the ratio of anion and cation exchange resins in a mixed bed according to any one of claims 1 to 3, characterized in that: In step (3), the molar concentration of the sodium hydroxide solution is 0.08 mol / L to 0.12 mol / L, and is calibrated with the reference substance potassium hydrogen phthalate.

5. The method for testing the ratio of anion and cation exchange resins in a mixed bed according to any one of claims 1 to 3, characterized in that: In step (3), the molar concentration of the silver nitrate solution is 0.08 mol / L to 0.12 mol / L, and is calibrated with the reference substance sodium chloride.

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