Alkali content detection method for modified chlorine-type resin
Through the alkali level detection method of the modified chlorine resin, the titration reaction of alkali and acid and the release step of sodium sulfate, the problem of poor accuracy and repetition of alkali level detection of chlorine-type weak alkali quaternary ammonium resin in the prior art is solved, and higher detection accuracy and application effect are achieved.
Patent Information
- Application Number
- CN202411747822.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-04-25
AI Technical Summary
In the prior art, the alkali level detection of chlorine-type weak alkali quaternary ammonium resin is easily affected by reaction conditions, and its accuracy and repeatability are poor.
A method for detecting alkali amount of modified chlorine resin is adopted. By contacting the resin with excess alkali, it is converted into a hydroxide resin, and then neutralizing with excess acid, the remaining acid is titrated with a standard sodium hydroxide alkali solution, the chloride ions in the resin are released into the solution in combination with excess sodium sulfate, and the chlorine content is titrated with a standard silver nitrate solution.
The accuracy and repeatability of alkali detection of chlorine-type weak alkali quaternary ammonium resin is improved, especially in water treatment and drinking water purification.
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Abstract
Description
Technical Field
[0001] The present application relates to a method for detecting the alkali content of a modified chlorine-type resin, and belongs to the technical field of alkali content detection. Background Art
[0002] Quaternary ammonium resin is a type of ion exchange resin, which is widely used in water treatment, pharmaceutical, food industry and chemical industry. Chlorine-type weak base quaternary ammonium resin refers to a resin whose main chain contains a highly polar nitrogen heterocyclic structure, and its exchange group is a quaternary ammonium salt with chloride ions. Unlike strong acid and strong base ion exchange resins, weak base quaternary ammonium resin has weak ion exchange capacity, but due to its hydrophilicity and good selectivity, it shows unique advantages in certain specific applications.
[0003] Chloride-type weak base quaternary ammonium resins usually exist in the form of chloride ions, and improve water quality by exchanging with other negatively charged ions. The alkalinity of chlorine-type weak base quaternary ammonium resins refers to the number of hydrogen ions that can be neutralized with acids, and is usually used to measure the ion exchange capacity of the resin. By measuring the alkalinity, the activity, regeneration effect and processing capacity of the resin in practical applications can be evaluated. Therefore, understanding the alkalinity of chlorine-type weak base quaternary ammonium resins and their determination methods is of great significance for improving their application effects, optimizing process parameters, and ensuring the efficiency of water treatment and other industrial processes.
[0004] Alkali titration is a commonly used analytical method, usually referring to the determination of the content of the substance to be tested through an acid-base neutralization reaction. In the analysis of weak-base quaternary ammonium resins, the standard titration method is to titrate the unreacted acid with a known concentration of standard base after the resin reacts with an excess of standard acid, and finally obtain the exchange capacity of the resin. Unlike strong-base resins, the reactive groups of weak-base quaternary ammonium resins are relatively mild to acidic substances, so special attention should be paid to the optimization of reaction conditions during the titration process. Summary of the invention
[0005] In order to solve the problem that the alkali content of chlorine-type weak base quaternary ammonium resin is susceptible to reaction conditions and has poor precision and repeatability in the prior art, the present application proposes a technical solution for the detection of alkali content of chlorine-type weak base quaternary ammonium resin, the purpose is to fill the technical gap of tracking the alkali content change of chlorine-type strong base quaternary ammonium resin after catalysis or adsorption, the basic principle of the titration method used in the technical solution of the present application is to contact a certain amount of resin with excessive alkali, convert the resin into a hydroxide-type resin, and then utilize excessive acid to neutralize, and utilize standard sodium hydroxide alkaline solution to titrate the remaining acid to obtain the total capacity of resin exchange. Then utilize excessive sodium sulfate to release the chloride ions in the resin into the solution, and then use standard silver nitrate solution to titrate the chlorine content. Compared with traditional solid analysis method, this method has higher precision and repeatability. Especially in water treatment and drinking water purification, neutral and slightly alkaline chlorine-type weak base quaternary ammonium resins show superiority in the analysis of alkali titration.
[0006] This application adopts the following technical solutions:
[0007] According to the first aspect of the present application, a method for detecting the amount of alkali in a modified chlorine-based resin is provided, comprising the following steps:
[0008] S1, weighing a weak base quaternary ammonium resin sample with a weight of m1, immersing it in a C0 sodium hydroxide solution, stirring for 1, and then taking it out to obtain a sodium hydroxide modified resin sample with a water content of x1;
[0009] The sodium hydroxide modified resin sample is immersed in a hydrochloric acid solution with a concentration of C1 and stirred for II, then filtered and the filtrate I is collected. The test solution containing the filtrate I is subjected to acid-base titration to the first titration endpoint with a sodium hydroxide solution with a concentration of C2, and the consumed volume of sodium hydroxide V1 is recorded. The total alkali content Q1 is calculated using formula I:
[0010]
[0011] S2, weighing a weak base quaternary ammonium resin sample with a weight of m2, immersing it in a sodium sulfate solution with a concentration of C4 and stirring it III, filtering it to obtain a weak base modified resin sample with a water content of X2, and collecting the filtrate II;
[0012] Use silver nitrate solution with a concentration of C to titrate the test solution containing filtrate II and the blank sample to the first titration endpoint, record the volume V2 of silver nitrate solution consumed in the titration of the blank sample and the volume V3 of silver nitrate solution consumed in the titration of filtrate II, and calculate the chloride ion content Q2 using formula II:
[0013]
[0014] S3. Calculate the base amount Q3 of the weak base quaternary ammonium resin using formula III:
[0015] Q3=Q1-Q2 formula III.
[0016] Optionally, the step further comprises: repeating step 1 to step S3 at least once, and taking the average value of the alkalinity Q3 calculated each time as the alkalinity of the weak base quaternary ammonium resin.
[0017] Optionally, the water contents X1 and X2 in the present application are measured using the GB / T 5759-2000 method.
[0018] In formula I, Q1 refers to the ion exchange capacity of the hydroxide type anion exchange resin (mmol / g), 100 is the standard titration amount of hydrochloric acid solution (mL), C1 refers to the standard titration concentration of hydrochloric acid solution (mmol / mL), C2 refers to the concentration of the standard titration solution of NaOH (mmol / mL), V1 refers to the volume of the standard sodium hydroxide titration solution consumed by the titration soaking solution (mL), m1 refers to the mass of the resin sample (g), and X1 refers to the water content of the sodium hydroxide modified resin sample (%); in formula II, Q2 refers to the ion exchange capacity of the chloride type anion exchange resin (mmoL / g), V2 refers to the volume of the AgNO3 standard solution consumed by the blank sample (mL), V3 refers to the volume of the AgNO3 standard solution consumed by the titration resin sample (mL), C refers to the concentration of the AgNO3 standard solution (mol / L), m2 refers to the mass of the resin sample (g), and X2 refers to the water content of the weak base modified resin sample (%); in formula III, Q3 is the ion exchange capacity of the acetate anion exchange resin (mmol / g).
[0019] Optionally, in step S1, the concentration C0 of the sodium hydroxide solution is 1.95-2.05 mol / L.
[0020] Optionally, the concentration C1 of the hydrochloric acid solution is 0.095 to 0.105 mol / L.
[0021] Optionally, the sodium hydroxide solution C2 is 0.095-0.105 mol / L.
[0022] Optionally, in step S1, the weight ratio of the weak base quaternary ammonium resin sample to the sodium hydroxide solution is 1:50-55.
[0023] Optionally, in step S1, the weight ratio of the sodium hydroxide modified resin sample to the hydrochloric acid solution is 1:50-55.
[0024] Optionally, the conditions for stirring I, stirring II, and stirring III independently include: stirring at 40° C. to 60° C. for 4 h to 6 h under closed conditions.
[0025] Optionally, in step S1, the test solution containing filtrate I comprises filtrate I, water, and phenolphthalein reagent;
[0026] The volume ratio of the filtrate I to water and phenolphthalein reagent is 1:2:0.016-0.024.
[0027] Optionally, in step S2, the test solution containing filtrate II comprises filtrate II, water, and potassium chromate reagent.
[0028] Optionally, the volume ratio of the filtrate II to water and potassium chromate reagent is 1:2:0.016-0.024.
[0029] Optionally, in step S2, the concentration C4 of the sodium sulfate solution is 1.95-2.05 mol / L.
[0030] Optionally, in step S2, the concentration C of the silver nitrate solution is 0.095-0.105 mol / L.
[0031] Optionally, in step S2, the weight ratio of the weak base quaternary ammonium resin sample to the sodium sulfate solution is 1:50-55.
[0032] Optionally, medium-speed filter paper is used for vacuum filtration during the filtration process.
[0033] The beneficial effects of this application include:
[0034] The method for detecting the alkali content of the modified chlorine-type resin provided in the present application can obtain the total amount of exchangeable ions and the chlorine content in the resin, and the weak base content in the chlorine-type quaternary ammonium resin can be obtained by subtracting them. The detection method is simple to operate and has high accuracy, meets the rapid detection needs of enterprises, and is convenient for monitoring in actual production. DETAILED DESCRIPTION
[0035] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.
[0036] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.
[0037] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.
[0038] The preparation method of the chlorine-type quaternary ammonium resin catalyst modified with acetate used as the weak base quaternary ammonium resin sample in the present application is as follows: 10g of chlorine-type quaternary ammonium resin and an appropriate amount of KAC are uniformly mixed (the molar ratio of chlorine content to acetate is 1:2), and dispersed in 150g of EtOH. The above mixture is mixed and stirred at 10°C for 24h, during which the KCl suspension is separated by pen analysis every twelve hours, and then the obtained resin catalyst is fully washed with EtOH 3 times, and vacuum dried at 70°C for 4h to obtain the target catalyst.
[0039] Example 1 Alkali content detection method of modified chlorine-type resin
[0040] The chloride-type quaternary ammonium resin catalyst modified with acetate is used as a weak base quaternary ammonium resin sample for determination, and the specific steps include:
[0041] Step 1, weigh 2 g of a weak base quaternary ammonium resin sample, add 100 g of a 2 mol / L sodium hydroxide solution, stir for 4 h at 40° C. in a sealed condition and take out;
[0042] Step 2, immersing the treated quaternary ammonium resin in 100 mL of a standard hydrochloric acid solution, stirring for 4 hours under a closed condition at 40° C., and filtering to obtain a sodium hydroxide modified resin sample, and collecting the filtrate;
[0043] Step 3, use sodium hydroxide solution to perform acid-base titration on the test solution containing the filtrate (25mL of the filtrate in step 2+50mL of pure water+2 drops of phenolphthalein reagent) to the first titration endpoint (the solution turns red), and record the volume V1 of the standard sodium hydroxide titration solution consumed by the titration soaking solution;
[0044] Step 4, using formula I to calculate the total alkali content Q1 of the sample in step 1;
[0045]
[0046] Wherein the total alkali amount Q1 refers to the ion exchange capacity of the hydroxide type anion exchange resin (mmol / g), 100 is the standard titration amount of hydrochloric acid solution (mL), C1 is the titration concentration of standard hydrochloric acid solution (0.1mmol / mL), C2 is the concentration of NaOH standard titration solution (0.1mmol / mL), V1 is the volume of the standard sodium hydroxide titration solution consumed by the titration soaking solution (mL), m1 is the mass of the weak base quaternary ammonium resin sample after modification in step 1 (g), and X1 is the water content of the sodium hydroxide modified resin sample (%);
[0047] Step 5, weigh another 2 g of the modified weak base quaternary ammonium resin sample, add 100 mL of 2 mol / L sodium sulfate solution, stir for 4 h under 40° C. sealed conditions and filter to obtain a weak base modified resin sample, and collect the filtrate;
[0048] Step 6, utilize AgNO3 standard solution to the solution to be measured (25mL filtrate of step 5+50mL pure water+2 drops of potassium chromate reagent) containing filtrate and blank sample (pure water) respectively carry out chlorine content titration, titrate to the first titration end point (solution turns red), record V2 as the blank sample consumption AgNO3 volume (mL) of standard solution, V3 is the titration resin sample consumption AgNO3 volume (mL) of standard solution;
[0049] Step 7, using formula II to calculate the chloride ion content Q2 in the sample of step 5;
[0050]
[0051] Wherein, the content Q2 of chloride ion refers to the ion exchange capacity (mmoL / g) of chlorine-type anion exchange resin, V2 is the blank sample consumption AgNO3 volume (mL) of standard solution, V3 is the titration resin sample consumption AgNO3 volume (mL) of standard solution, C is AgNO3 concentration of standard solution (0.1mol / L), m2 is the mass (g) of the weak base quaternary ammonium resin sample after step 5 modification, and X2 is the water content (%) of the weak base modified resin sample;
[0052] In this embodiment, the water content X1 and X2 are measured using the GB / T 5759-2000 method;
[0053] Step 8: Calculate the base content Q3 of the weak base quaternary ammonium resin using formula III.
[0054] Q3=Q1-Q2 Formula III
[0055] Here, the base amount Q3 refers to the ion exchange capacity (mmol / g) of the acetate anion exchange resin.
[0056] Repeat steps 1 to 8 three times, and take the average value of Q3 calculated three times as the alkalinity test value of the chloride-type quaternary ammonium resin. The result is shown in Table 1, and the alkalinity is 2.89 mmol / g.
[0057] Table 1
[0058]
[0059]
[0060] Comparative Example 1
[0061] In this comparative example, the exchange capacity method of the hydroxide type anion exchange resin in the national standard GB / T 5760-2000 was used to measure the alkali content of the chloride type weak base quaternary ammonium resin which is the same as that in Example 1. The results are shown in Table 2.
[0062] Table 2
[0063]
[0064] Since the alkalinity of the strong base position in the chloride-type quaternary ammonium resin is relatively low, the alkalinity of the strong base position measured using a mixed solution of methylene blue and methyl red as an indicator will be higher, resulting in a lower alkalinity of the quaternary ammonium resin after weak base modification.
[0065] In summary, compared with the method of using the national standard GB / T 5760-2000 for determining and calculating the alkalinity of the chloride-type weak base quaternary ammonium resin using the exchange capacity of the hydroxide-type anion exchange resin, the detection method of the technical solution of the present application has more accurate results.
[0066] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for detecting the amount of alkali in a modified chlorine-based resin, characterized in that: The steps include: S1, weighing a weak base quaternary ammonium resin sample with a weight of m1, immersing it in a C0 sodium hydroxide solution, stirring for 1, and then taking it out to obtain a sodium hydroxide modified resin sample with a water content of x1; The sodium hydroxide modified resin sample is immersed in a hydrochloric acid solution with a concentration of C1 and stirred for II, then filtered and the filtrate I is collected. The test solution containing the filtrate I is subjected to acid-base titration to the first titration endpoint with a sodium hydroxide solution with a concentration of C2, and the consumed volume of sodium hydroxide V1 is recorded. The total alkali content Q1 is calculated using formula I: S2, weighing a weak base quaternary ammonium resin sample with a weight of m2, immersing it in a sodium sulfate solution with a concentration of C4 and stirring it III, filtering it to obtain a weak base modified resin sample with a water content of X2, and collecting the filtrate II; Use silver nitrate solution with a concentration of C to titrate the test solution containing filtrate II and the blank sample to the first titration endpoint, record the volume V2 of silver nitrate solution consumed in the titration of the blank sample and the volume V3 of silver nitrate solution consumed in the titration of filtrate II, and calculate the chloride ion content Q2 using formula II: S3. Calculate the base amount Q3 of the weak base quaternary ammonium resin using formula III: Q3=Q1-Q2 formula III.
2. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: The step further includes: repeating step 1 to step S3 at least once, and taking the average value of the alkalinity Q3 calculated each time as the alkalinity of the weak base quaternary ammonium resin.
3. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: In step S1, the concentration C0 of the sodium hydroxide solution is 1.95-2.05 mol / L; Preferably, the concentration C1 of the hydrochloric acid solution is 0.095 to 0.105 mol / L; Preferably, the sodium hydroxide solution C2 is 0.095 to 0.105 mol / L.
4. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: In step S1, the weight ratio of the weak base quaternary ammonium resin sample to the sodium hydroxide solution is 1:50-55; Preferably, in step S1, the weight ratio of the sodium hydroxide modified resin sample to the hydrochloric acid solution is 1:50-55.
5. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: The conditions of stirring I, stirring II and stirring III independently include: stirring at 40° C. to 60° C. for 4 h to 6 h under closed conditions.
6. The method for detecting the amount of alkali in the modified chlorine-based resin according to claim 1, characterized in that: In step S1, the test solution containing filtrate I comprises filtrate I, water, and phenolphthalein reagent; The volume ratio of the filtrate I to water and phenolphthalein reagent is 1:2:0.016-0.
024.
7. The method for detecting the amount of alkali in the modified chlorine-based resin according to claim 1, characterized in that: In step S2, the test solution containing filtrate II comprises filtrate II, water, and potassium chromate reagent; The volume ratio of the filtrate II to water and potassium chromate reagent is 1:2:0.016-0.
024.
8. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: In step S2, the concentration C4 of the sodium sulfate solution is 1.95-2.05 mol / L; Preferably, in step S2, the concentration C of the silver nitrate solution is 0.095-0.105 mol / L.
9. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: In step S2, the weight ratio of the weak base quaternary ammonium resin sample to the sodium sulfate solution is 1:50-55.
10. The method for detecting the amount of alkali in modified chlorine-based resin according to claim 1, characterized in that: During the filtration process, medium-speed filter paper is used for vacuum filtration.