one.Conventional regeneration treatment
Ion exchange resins are used for a period of time after adsorption of impurities is close to saturation, it is necessary to regeneration treatment, chemical used in the resin adsorption ion and other impurities eluting removed, so as to restore the original composition and performance. In practice, in order to reduce the recycling cost, the amount of the recycled agent should be controlled properly, the performance of the resin can be recovered to the most economical and reasonable level of regeneration, and the control performance can be recovered from 70 to 80%. If you want to achieve a higher level of regeneration, the regeneration dose should be increased, the utilization rate of the regenerative agent is decreased.
Resin regeneration should be based on the types and characteristics of the resin, as well as the operation of the economy, the choice of appropriate recycling agents and working conditions.
The regeneration property of resin is closely related to its type and structure. Strong acid and strong alkali resin regeneration is more difficult, need regenerative dose than the theoretical value high considerable; and weakly acidic or weakly basic resin is easy to regenerate, the regeneration dose only slightly more than the theoretical value. In addition, the resin with high pass and low crosslinking degree is easy to regenerate, and the resin with high gel type and high cross-linking degree should have longer regeneration reaction time.
The type of regeneration agent should be selected according to the type of ion of the resin, and appropriate choice of acid, alkali or salt. For example: sodium type strong acid cation resin available 10% NaCl solution regeneration, dosage for the exchange capacity of 2 times (with NaCl content for L 117g/ resin); hydrogen type strong acidic resin regeneration by the strong acid and sulfuric acid to prevent adsorbed on the resin was calcium and reacted with sulfuric acid to produce calcium sulfate precipitates. To this end, it is advisable to first pass through 2% ~ 1 of dilute sulfuric acid regeneration.
Chloride type strong basic resin, mainly in NaCl solution to regenerate, but with the addition of a small amount of alkali contributes to the resin adsorption of pigment and organic matter dissolved washout, so usually containing alkali salt solution of 10% NaCl + 0.2% NaOH regeneration, routine dosage per liter of the resin with 150 ~ 200 g NaCl and 3 ~ 4G NaOH. OH type anion exchange resin is regenerated by 4%NaOH solution.
The chemical reaction of resin regeneration is the reverse reaction of the exchange and adsorption of the resin. According to the balance principle of chemical reaction, improving the concentration of one side of the chemical reaction, can promote the reaction to the other side, it can improve the regeneration fluid concentration can accelerate the regeneration reaction, and achieve a higher level of regeneration.
In order to accelerate the regeneration of chemical reaction, the regeneration liquid is usually heated to 80 to 70 degrees Celsius. The flow rate of the resin is 1 ~ 2 BV/h. Can also be used in the first fast slow method, in order to give full play to the effectiveness of the regenerative agent. Regeneration time is about one hour. Then use soft water downstream washing resin about an hour (content of about 4 BV), to be washed drain water Qing after, backwash water again, until the eluate is colorless, no turbidity.
Some resin after backwashing and regeneration, to adjust the pH value. Because the recycled liquid often contains alkali, even after the regeneration of the resin after washing, also often with alkaline. Some decolorization resin (especially weakbaseresin) should work in subacidity under. At this time can pass into dilute hydrochloric acid, the resin pH value dropped to about 6, water washing, washing each time.
Resin in use for a long time, due to its adsorbed part of impurities (especially macromolecular colloidal organic matter) is not easy to be conventional regeneration processing the elution, and gradually accumulated and the contamination of resin, the resin performance degradation. At this time to use a special method to deal with. For example: cationic resin containing nitrogen amphoteric compound pollution, available 4% NaOH solution, will dissolve it and drain; anion exchange resin by organic pollution, improve the alkali and salt solution of NaOH concentration to 0.5 ~ 1.0% to dissolved organic matter.
Two, special regeneration treatment
Resin with serious pollution, acid or alkaline salt solution treatment repeatedly. If organic matter in 10% NaCl +1%NaOH alkali and salt solution, and then 4%HCl or were used 10% NaOH and 1% HCl dissolved inorganic matter, then with 10% NaCl +1%NaOH processing. In about 70 DEG C.
If the effect of the above treatment is not up to the requirements, can be treated with oxidation. After the water washing resin, into the concentration of 0.5% sodium hypochlorite solution, control flow rate of 2 ~ 4 bv / h, the 10 ~ 20BV, then water washing, then salt treatment. It should be noted that the oxidation process may be the resin structure of large molecules in the connection of oxidation, resulting in degradation of the resin, swelling degree increases, easy to break, it should not be used. 50 cycles are usually used to carry out an oxidative treatment. Because of the strong resistance to oxidation of chlorine resin, the application of the salt water treatment before oxidation treatment, it can be changed into chloride type, which can avoid the change of pH value in the treatment process, and make the oxidation more stable.