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I'm currently studying ion exchange resins and generally getting a bit stuck on some points of information which I do not fully understand / are not very well explained within the literature.

I understand that resins having varying selectivity or affinity for a particular ion and selectivity generally increases with increased valance number, atomic weight, reduced hydrated radius, etc.

I have seen some information that selectivity reversal will occur when the solution has high TDS e.g., sulphate will have a far higher affinity than chloride for a strong base anion resin within a solution with low TDS; however, at high TDS the affinity of these ions for the resin will be reversed - chloride will have a greater affinity than sulphate.

Any idea whether this is correct and what the mechanism causing this change is?

share|improve this question
You don't need to debase yourself, we're all friendly here. Even if it were a basic question (which it really isn't), everyone has to start somewhere. – jonsca Feb 19 '13 at 4:19

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