Breakthrough and Leakage

The consequences of the coflow regeneration pattern become immediately apparent at the start of the next loading cycle. At the top of the column ion exchange is complete giving an equivalent concentration of A ions which then travel unaffected down the bed  

Upon nearing the outlet, ions A encounter resin partially in the B ionic form and ion exchange can occur allowing a quantity of ion 3 to appear in the column effluent (product)  

In order to sustain the benefits from fixed bed counterflow regeneration it is imperative that the resin bed remains consolidated and undisturbed at all times during loading and reverse flow regeneration. Some ways this is achieved are discussed later in Chapter 10, but it follows that conventional backwashing of a counterflow designed column is undesirable since the inevitable bed disturbance causes exhausted resin to mix with the lightly loaded resin zone at 

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In practice the exchange reactions depicted above are not complete owing to the leakage of residual ions as described previously in Chapter 7 (Column Breakthrough and Leakage ). 

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