Regeneration of ion exchange resins

I. Regeneration of conventional
Ion exchange resin (IONRESIN) used for a period of time, the adsorption of impurities close to saturation, it is necessary for regeneration treatment, the resin with a chemical adsorbed by washed to remove ions and other impurities, so as to restore the original composition and performance. In practical application, to reduce the recycling costs, recycling to proper control of dosage, the performance of the resin back to the regeneration of the most economical and reasonable level, typically a performance recovery level of 70 ~ 80%. If you want to achieve higher recycling levels, the dose to a significant increase in regeneration, regenerant utilization decreased.
Resin regeneration should be based on the type of resin, features, and run the economy, select the appropriate pharmacy and working conditions of regeneration.
Regeneration of resin characteristics and it is closely related to the type and structure. Strong acid and strong basic resin regeneration difficult, needed regeneration of high doses of lot more than the theoretical value; the weak acid or weak basic resin is more easily recycled, renewable dose used only slightly more than the theoretical value. In addition, the large degree of crosslinking of low pass and easily recycled resin, and cross-linked gel-type and high regeneration of the resin will have to longer reaction time.
The type of regenerant ions should be based on the type of resin used, and appropriate selection of lower-priced acid, alkali or salt. For example: Na strong acid resin available yang 10% NaCl? Solution regeneration, dosage is 2 times its exchange capacity? (With NaCl content of 117g / l? Resin); hydrogen type strongly acidic resin regenerated with strong acid, sulfuric acid when resin to prevent the calcium sulfate reacts with calcium sulfate precipitates. To this end, advised pass into the 1 to 2% of the sulfuric acid regeneration.
Chloride-type strongly basic resin, mainly NaCl? Solution to regenerate, but a small amount of resin base will help to dissolve the pigment and organic matter washed out, it usually containing 10% NaCl + 0.2% NaOH? Regeneration of alkali salt solution conventional dosage of resin per liter with 150 ~ 200g NaCl?, and 3 ~ 4g NaOH. OH-type strong base anion resin is regenerated with 4% NaOH solution.
Resin regeneration of the chemical reaction is the original exchange resin adsorption of the reverse reaction. By the chemical reaction equilibrium principle, increase the concentration of chemical substances either party may accelerate the reaction to the other party, so to improve regeneration concentration can accelerate the regeneration reaction, and achieve a higher level of regeneration.
To speed up the regeneration of the chemical reaction, usually first regeneration fluid heated to 70 ~ 80 ℃. It is the flow rate through the resin is generally 1 ~ 2 BV / h. Can be applied quickly and then slow way to give full play to the effectiveness of regeneration agents. Regeneration time is about one hour. Then rinse with soft water resin downstream about one hour (water about 4BV), to be drained after washing, then backwash water to wash out the liquid is colorless, no cloudy so far.
Some resin after washing in the regeneration and anti-, to adjust the pH. Because the regeneration fluid often contain alkali, even after washing the regenerated resin, often with alkaline. Some decolorization resin? (Especially weakly basic resin)? Wish to work in slightly acidic. At this point can access dilute hydrochloric acid to make resin? PH value dropped to about 6, and then water is washing, washing each one against.
(IONRESIN) resin using a longer time, as part of its impurities adsorption (particularly macromolecular colloidal organic matter) can not easily be eluted by conventional regeneration treatment, and gradually accumulated while the resin pollution, reduce the resin performance. Then use a special approach. For example: gender cation resin compounds by nitrogen pollution, can be used 4% NaOH? Buffer, dissolve and drain it; anion resin, organic pollution, can increase salt solution in alkaline NaOH? Concentration from 0.5 to 1.0%, to dissolved organic matter.
Second, a special recycling deal
More polluting resin, acid or alkaline salt solution can be repeated processing, such as the first with 10% NaCl +1% NaOH alkali salts dissolved organic matter, and then 4% HCl? Or respectively 10% NaOH? And 1% HCl? dissolved inorganic, then reuse 10% NaCl +1% NaOH treatment, carried out at about 70 ℃. If the results do not meet the above treatment can be used oxidation process. The water washed resin, which leads to concentration of 0.5% sodium hypochlorite solution, the control flow rate of 2 ~ 4BV / h, through volume 10 ~ 20BV, then water washing, and then saline. Should be noted that oxidation may be the structure of macromolecular resin connection key oxidation, resulting in resin degradation, swelling increases, easily cracked, it should not be used. Usually use only after a 50-cycle oxidation. As the chloride resin has a high tolerance to oxidation, so resin before application of saline in the oxidation treatment, into chlorine, which can avoid the processing of the pH value changes, and to oxidation stable.