DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

Ion Exchange Cleaning Procedures
Chlorine treatment: Sodium hypochlorite (NaOCl 5H2O or bleach cleaning is a very intense treatment for
sterilizing and removing organic contaminants on cation exchange resins. Note that chlorine can be
explosive under certain conditions.
The recommended procedure for cation resins is as follows:
1. Regenerate the resin (hydrogen form). If the resin has iron or other metal contamination, pretreat with
about two bed volumes of 10% HCl solution.
2. Ensure that the resin is completely exhausted by treating with brine solution (for strong acid cation
resins) or caustic (for weak acid cation resins) because any residual H + on the resin can lead to the
generation of free Cl2. Take care to allow for resin swelling.
3. Use a sodium hypochlorite solution of 0.10% concentration (1000 ppm).
4. Apply 143 g free Cl2/ft 3 (5 g/L) resin by passing two bed volumes of the NaOCI solution at ambient
temperature down through the resin bed with a 30–45 minute contact time. Allow the resin to soak in
the solution for 1–2 h.
5. Rinse out with one to two bed volumes of deionized water.
6. For the most effective treatment, apply more solution, repeating step 4. Perform a final rinse with
three to four bed volumes of deionized water (until no Cl2 is detectable in effluent).
The recommended procedure for anion resins is as follows:
1. Put resin into exhausted (Cl) form. If the resin has iron or other metal contamination, pretreat with
about two bed volumes of 10% HCl solution.
2. Use a sodium hypochlorite solution of 0.05% concentration (500 ppm).
3. Apply 57 g free Cl2/ft 3 (2 g/L) resin by passing two bed volumes of the NaOCI solution at ambient
temperature through the resin bed with a 30–45 minute contact time. Measure the effluent and stop if
free Cl2 reaches a level of about 10% of the inlet concentration.
4. Rinse out with three to four bed volumes of deionized water (until no Cl2 is detectable in effluent).
Reference Document: Tech Facts 177-01744
DOWEX Ion Exchange Resins 60 Water Conditioning Manual