[student10]

Hello,

I would like to know if someone knows a good protocol to regenerate both amberlyst 15 and 21 ion exchange resin.

Thanks.

[Babcock_Hall]

Do you know which Dowex resins are most similar to these two?

[salteen]

I haven't used either of these, but I do regularly use Amberlite 120, which is also a strongly-acidic sulfonic acid resin.  I put a half-inch layer of the resin in a ~50mL glass frit, fill with 10% HCl, and let it drain by gravity with occasional stirring - if it doesn't empty by gravity, I'll let it sit for about 10 min and then use suction.  Then I wash the resin with 5-10 column volumes of water (with suction) until the water flowing through is pH 6-7.  Then wash once with methanol to remove organic impurities. 

I use this regularly to re-acidify solutions of NaOMe or K₂CO₃.  But as I said, this is a slightly different resin, so YMMV.

[Babcock_Hall]

What counterion is presently bound?