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Cation Exchange Column
2155
3 OPERATION
3.1 Start-up and Operation
Note. Once the resin is added to the column, keep the
column upright.
1. Remove the top end cap.
2. Empty a full resin pack (J/2155/500) into the column.
3. Replace the end cap.
4. Shake the column gently so that the resin settles.
5. Clip the column to the wall.
6. Attach the sample tubing to the end caps so that the
direction of flow is downwards.
7. Open and adjust the sample flow regulator valves to
achieve the recommended flow rate of 100 to
-1
300 ml min
.
Note. It may take several hours before meaningful results
are made due to small amounts of trapped air. This trapped
air is dissolved slowly in a de-aerated sample.
4
4 MAINTENANCE
4.1 Maintenance
4.1.1 Regeneration
Eventually the hydrogen ions in the resin become depleted and
the exchange process breaks down. The concentration of
unwanted ions then rises at the outlet of the column; this is
known as breakthrough.
Fortunately, the exchange process is reversible and resin can be
regenerated to its original form by treatment with a solution rich
in hydrogen ions, that is, an acid solution.
As the resin is exhausted, its colour changes from orange to
dark red at a boundary that moves progressively down the
column. When the boundary approaches the bottom of the
column, the resin must be regenerated.
Exhausted resin can be processed in one of three ways:
Disposed of and the column refilled with fresh resin.
Removed,
collected
regenerated when a reasonable volume of resin has been
collected.
Regenerated in situ – see Section 4.1.2
4.1.2 Procedure for Regeneration
1. Close the inlet valve (connected to the top of the column)
or, in the case if a duty/standby column arrangement,
switch the inlet and outlet valves to the standby column.
2. Remove the quick-release coupling from the top and
bottom of the spent column.
3. Mark the top of the column and pull it from the mounting
clips.
4. Fit a spare column if available.
5. Take the spent column, invert and support in a vertical
position. Back-flush the column with demineralised water
at 30 litres (6.6 gal) per minute for 10 minutes to remove
particulate deposits.
6. From the top of the column pass 3.5 litres (0.77 gal) of 5%
hydrochloric acid down the column over a period of
between 10 to 30 minutes until the resin is restored to its
original orange colour.
7. Flush the column by passing demineralised water down
the column at approximately 3.5 litres (0.77 gal) per
minute. This takes about 30 minutes to complete.
8. Return the column to service or, if putting in storage,
ensure that it is filled with water and kept wet.
3 OPERATION
in
a
suitable
container
IM/2155 Rev. G
and
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