Resin Common Problems Resin Pretreatment of Resin In industrial products of ion exchange resins, a small amount of organic oligomers and an inorganic impurity are often contained. In the initial stage of use, it will gradually dissolve and release, affecting the quality of the effluent or the quality of the product. Therefore, the new resin must be pretreated before use, as follows:
1. After the resin is charged into the exchanger, the resin layer is backwashed with clean water at a development rate of 50-70% until the water is clear, odorless, and no finely divided resin.
2. Pass the resin layer at a flow rate of 2 m/h with about 2 times the resin volume of 4-5% HCl solution. After all the infusion, soak for 4-8 hours, drain the acid, rinse with clean water until the water is neutral. The flushing flow rate is 10-20 m/h.
3. Pass and soak in a solution of about 2 times the volume of the resin in 2-5% NaOH according to the above method of introducing HCl. Drain the lye and rinse with clean water until the effluent is neutral. The flow rate is the same as above. If the acid or lye can be repeated 2-3 times, the effect is better. After the pre-treated resin, the amount of regenerant should be appropriately increased during the first operation to ensure sufficient regeneration of the resin. Resin Silicon Contamination Treatment Methods Silicone compound contamination occurs in strong base anion exchangers, especially in equipment and systems where strong and weak anion resins are used in combination. As a result, the silicon removal efficiency of the cathode exchanger is often reduced. The cause of this contamination is insufficient regeneration or failure to regenerate in time after resin failure. The treatment method can be soaked and dissolved in a dilute warm alkali solution. The lye concentration was 2% and the temperature was about 40 degrees. In case of serious pollution, it can be circulated and washed with warmed 4% sodium hydroxide solution.
Second, the resin is contaminated by organic matter treatment method Styrene strong alkaline resin is susceptible to organic pollution, the symptoms are:
(1) The color of the resin becomes darker;
(2) The work exchange capacity decreases;
(3) The conductivity of the effluent increases;
(4) The pH of the effluent is lowered;
(5) The effluent silica content increases;
(6) The amount of washing water increases.
The basic measure to prevent organic pollution is to remove the organic matter in the water as much as possible in the pretreatment, and to use anti-pollution resin, such as macroporous weak base anion resin, acrylic acid resin is very effective against organic pollution. The commonly used resuscitation method is the alkaline salt method. That is, a mixture of 10% NaCl and 4-6% NaOH is used in an amount of 3 bed volumes, and the resin layer is passed through at a slow flow rate. When the second bed volume is passed through, the resin is immersed for 8 hours or left overnight. 3 bed volume mixture. The mixture should be warmed to 40-50 degrees. If about 1% sodium phosphate or sodium nitrate is added to the mixed solution, or the resin layer is stirred in combination with compressed air, the effect is further improved. When the alkaline salt method is not effective, it may be considered to wash with a sodium hypochlorite solution. At this time, in the single bed or mixed bed system, the resin is completely ineffective by passing at least one bed volume of 10% NaCl solution through the resin layer. The concentration of sodium hypochlorite solution is 1% of the available chlorine content, and the amount is 3 resin bed volumes. The second bed volume solution was immersed in the resin bed for 4 hours without the solution being heated. Finally, traces of sodium hypochlorite must be rinsed (rinsed) clean, including waste from the sewer.
III. Treatment Method of Resin Iron Pollution The iron in the cation resin is mainly derived from iron ions in the raw water, especially when the iron salt is used as a coagulant. The iron in the anion resin is mainly derived from the regenerant. The color of the resin contaminated with iron becomes darker, the exchange capacity is lowered, and the degradation of the anion resin is accelerated. The method of removing iron compounds is usually to soak the resin with a high concentration of hydrochloric acid (10-15%) with an inhibitor for 5-12 hours or even longer. It can also be treated with a complex such as citric acid, aminotriacetic acid or EDTA.
4. Suspended solids Suspended solids in the raw water will clog in the pores of the resin layer, thereby increasing the resistance to water flow and also covering the surface of the resin particles, thus reducing their working exchange capacity. In order to prevent the fouling of suspended solids, it is mainly to strengthen the pretreatment of raw water to reduce the suspended solid content in water. In order to remove the suspended matter in the resin layer, a method of increasing the number and time of backwashing or scrubbing with compressed air may be employed.
5. Calcium sulphate precipitation When there is a calcium sulphate-regenerating cation resin, if the operation is not proper, it is possible to precipitate calcium sulfate precipitate in the resin layer. At this time, not only is it difficult to clean after the regeneration, but there is always hardness in the eluate, and the exchange capacity of the resin is lowered. Measures to prevent the precipitation of calcium sulfate are to reduce the concentration of sulfuric acid in the regenerant and to increase the flow rate of the regenerant. It is also possible to adopt a step-by-step regeneration method in which the concentration is gradually increased and the flow rate is gradually slowed down. Once calcium sulfate is found to precipitate, it can be soaked in a -10% hydrochloric acid solution for 1-2 days, or recycled several times with hydrochloric acid.
6. Storage and transportation of resin
1. The ion exchange resin should be stored for a long time in the long-term storage, or the strong resin should be converted into a salt type. When the weak resin can be converted into the corresponding hydrogen type or free amine, it can also be converted into a salt type. In order to keep the resin stable, then always soak in clean water. If the equipment is to be drained, it should be sealed to prevent the resin from escaping.
2. The ion exchange resin contains a certain amount of balanced water, which should be kept moist during storage and transportation to prevent dehydration. The resin should be stored indoors or covered, and the ambient temperature should be 5-40 degrees. The bagged resin should avoid direct sunlight and keep away from heating devices such as boilers and heaters to avoid dehydration. If the resin is found to be dehydrated, do not put it directly in the water to prevent the dry resin from swelling and breaking with water. According to the degree of dehydration, it should be slowly added to the resin with about 10% saline. After soaking for several hours, gradually dilute with clean water.
3. When the ambient temperature is below zero or less, in order to prevent the resin from cracking due to internal water freezing, the insulation measures should be taken, or the resin should be stored in different concentrations of salt water according to the temperature conditions to prevent freezing. If the resin is found to have been frozen, it should be allowed to slowly thaw naturally, and it should not be applied to the resin by mechanical force.
4. Resin placed in the exchanger for long-term deactivation. In order to prevent irreversible contamination of the resin by microorganisms (such as algae, bacteria, etc.), the resin must be thoroughly backwashed before deactivation to remove suspended matter accumulated during operation. Pay attention to the regular flushing and changing of water, or after thorough backwashing, use the following measures: Anion resin: Dispense the resin layer twice with 3 times NaCl volume of 10% NaCl 2% NaOH mixture, each time for several hours, then row it go with. If necessary, rinse the resin motor with 2 times the resin volume of 0.2% hydrogen peroxide solution before re-enabling. Yang resin: 0.5% formaldehyde solution can be filled in the cation resin exchanger and piping system, and this concentration is maintained during the deactivation. It can also be soaked in saline solution and rinsed with 0.2% hydrogen peroxide or 0.5% formaldehyde solution before the equipment is reactivated.