I finally decided to recharge my unit.
I bought a 25kg bag of NaOH and a good sized bottle of HCl from which I prepared some recharging solutions.
On adding the NaOH the two resigns did, to some extent separate. I removed the most boyant one.
I rinsed the resin left in the TWP and then added the HCl - the resin over a period of an hour showed no visible change in color. The exception was a small amount of the more boyant resin that I had not been able to remove - that changed almost instantly to a sort of yellow color.
Similalry the resin taken out of the TWP and soaking in NaOH remained brown.
My original resin had never been green and was always a sort of brown color - over time it had mostly changed to a sort of purple/black color. From what I have read there are several brands on DI resin each of which uses a different color dye - I appear to not have the "green" one.
I decided to reverse the re-charging solutions. I put NaOH into the resin left in the TWP - it remained brown.
I put the HCl in the resin removed from the TWP - it immediately changed color - initinally yellow and finishing up at a sort of red-brown color.
I tested the TWP after reassembly by comparing input phosphate to output phosphate and as far as I can tell it is working.
My concern is that the generic recharging instrucitons indicate that the cationic resin should sink on exposure to NaOH and so get left in the TWP - in my case the reverse appears to have been true - should I be worried about this?
Perhaps I am misleading myself by noting that the resin removed from the TWP does change color when exposed to HCl?
I bought a 25kg bag of NaOH and a good sized bottle of HCl from which I prepared some recharging solutions.
On adding the NaOH the two resigns did, to some extent separate. I removed the most boyant one.
I rinsed the resin left in the TWP and then added the HCl - the resin over a period of an hour showed no visible change in color. The exception was a small amount of the more boyant resin that I had not been able to remove - that changed almost instantly to a sort of yellow color.
Similalry the resin taken out of the TWP and soaking in NaOH remained brown.
My original resin had never been green and was always a sort of brown color - over time it had mostly changed to a sort of purple/black color. From what I have read there are several brands on DI resin each of which uses a different color dye - I appear to not have the "green" one.
I decided to reverse the re-charging solutions. I put NaOH into the resin left in the TWP - it remained brown.
I put the HCl in the resin removed from the TWP - it immediately changed color - initinally yellow and finishing up at a sort of red-brown color.
I tested the TWP after reassembly by comparing input phosphate to output phosphate and as far as I can tell it is working.
My concern is that the generic recharging instrucitons indicate that the cationic resin should sink on exposure to NaOH and so get left in the TWP - in my case the reverse appears to have been true - should I be worried about this?
Perhaps I am misleading myself by noting that the resin removed from the TWP does change color when exposed to HCl?
