Ion exchange columnIt refers to a cylindrical pressure vessel used for ion exchange reactions and is an exchange equipment for ion exchange using the column method.
The regeneration of cation exchange columns is a key process for restoring resin exchange capacity through chemical methods, mainly including three stages: backwashing, regeneration, and forward washing. The specific operation is as follows:
1. Backwash (backwash)
Purpose: To loosen the resin layer, remove debris, bubbles, and impurities, and ensure uniform contact of the regeneration solution with the resin.
Operation:
Tap water (or effluent from the positive column) is introduced from the bottom of the column, and wastewater is discharged from the top at a flow rate of 1.5-2m ³/h.
Continue for 15-30 minutes until the effluent is clear and the liquid level is 10cm above the resin layer.
2. Regeneration (adding acid)
Regenerator: 4%~5% HCl solution (or sulfuric acid).
Operation:
Slowly add acid solution from the top of the column and control the flow rate (such as adding it in 30-45 minutes).
Maintain the liquid level height to avoid resin exposure.
When pollution is severe, alkaline salt solution+chelating agent compound solution can be used for treatment.
3. Regular washing
Purpose: To remove residual acid and regenerated products.
Operation:
Tap water is introduced from the top of the column, and wastewater is discharged from the bottom at a flow rate twice that of adding acid.
Wash until the pH of the effluent is 3-4 (tested with pH test paper), and there are no cations in the chromium black T-test.
It takes about 20-30 minutes.
4. Special treatment
Layered regeneration (mixed column): If it is a mixed ion exchange column, the layers need to be backwashed first, and then the anion and cation resins need to be regenerated separately.
Conductivity monitoring: The specific resistance of the regenerated effluent should be>5000 Ω· cm and pH>4 (anode).