How to clean ion exchange resin ?
Before using the ion exchange resin purchased in the market, in order to prevent impurities in the resin from polluting the water quality, the resin needs to be pretreated. The following steps are for pretreatment:
1. First, clean the resin with hot water. The cation resin can be cleaned with 70-80 ℃ hot water. The heat resistance of the anion resin is poor. Generally, 50-60 ℃ hot water is used. The hot water needs to be replaced every 15 minutes or so. After 4-5 times, the hot water can be replaced every 30 minutes or so. A total of 7-8 times is required until the water is clear.
2. Soak the resin with HCL with a concentration of 5% for about 4-8 hours, then discharge the water and clean the resin until the effluent is neutral
3. Soak the resin with 2-4% sodium hydroxide for the same soaking time as the previous step, then discharge the water and clean the resin until the effluent is neutral. Repeat this for 2-3 times, and the dosage for each time is twice of the resin volume.
4. HCL with concentration of 5% shall be used for the last soaking of cation exchange resin, and the effect is better if the dosage is doubled. Drain the acid solution and rinse it with clean water until it is neutral.
5. 4~5% NaOH solution is required for the last soaking of anion exchange resin, and the effect is better if the dosage is doubled. Drain the lye and rinse it with clean water until it is neutral.
6. The resin that has been out of the factory for a long time needs to be soaked with saturated salt. After treatment, it should be washed to clean before regeneration.
7. Pretreatment of weakly alkaline resin: soak the resin in warm water for 4-8 hours, wash it to PH=6, and then use it again; soak it in 2-4% sodium hydroxide for 4-8 hours, wash it to neutral, and wait for use.
8. For the resin used in medicine and food industry, it is better to soak it in ethanol for pretreatment, then alternately treat it with acid and alkali, and wash it with plenty of clean water until it is neutral for use.
9. The last acid or alkali passing through the exchange column during pretreatment depends on the required ion type.
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