Purolite 502E question.

[steve b]

Hi All, been testing my waters for my new set up.

Passing my tap water through Purolite 502E Nitrate removal resin and having some strange readings. If anyone uses this may know what's happening.

Tap water is ph 7.6 TDS 350 Kh 9 NO3 30ppm
Purolite 502E ph 6.8 TDS 420 Kh 3 NO3 0ppm

Drop in Ph, slight increase in TDS and large drop in Kh.

Will be adding this to remin my RO/DI for tanks.

[brewmaster15]

Steve, I dont use that but 2 questions... do you have to pretreat that resin? And is it an ion exchange resin?

[steve b]

Steve, I dont use that but 2 questions... do you have to pretreat that resin? And is it an ion exchange resin?

No pre treatment just wash and I believe it's an Anion resin, there seems to be some chemistry going on. Water looks good to use but just want to make sure before I start the fish going in. Might be worth while emailing Purolite direct.

nb just sent a note to Purolite.

[steve b]

Just an update. After aeration for 24hrs the PH back to tap parameters PH 7.6, Kh remains the same at Kh3

[brewmaster15]

Steve any idea where the increase in TDS came from?

[steve b]

Steve any idea where the increase in TDS came from?

Not sure, hope Purolite have some answers. Maybe the Calcium is being replaced with Sodium and that pushes up TDS?


Done a test with mixing the water 3:1 and get 120TDS 7Ph with 1Kh. Any idea how to increase Kh without increasing TDS or Ph... (don't think so). need to get water around 50 TDS 6.8Ph

[brewmaster15]

The only way I can think in your case is to strip the water down to almost nothing with a R/O coupled to DI.
. Then add a kH buffer .. it will also add tds but net result should be higher KH and a lower TDS. Im not sure how much TDS you will add back as thats going to depend on the buffer and is trial and error..

Hope that makes sense.

Incidentally if you use the RoDI you probably will not even need to worry about those Nitrate levels and using the 502 E resin.

[steve b]

Thanks, that will work as you say Trial & Error! I will keep everyone posted to what I end up with.

[Snug]

Interesting. I just ordered Purolite A520E. The drop in dKH must be the resin replacing carbonate with chloride which I think A520E comes preloaded with. I planned to use the A520E directly in my aquarium to remove nitrates.

If you regenerate A520E with caustic soda instead of table salt, the nitrate will be replaced with hydroxide instead of chloride which doesn't contribute to tds.

[steve b]

If you regenerate A520E with caustic soda instead of table salt, the nitrate will be replaced with hydroxide instead of chloride which doesn't contribute to tds.

Didn't know you could do it both ways thought it was only salt?

[Tschens]

Dear colleagues,
These kind of Purolite adsorbents are strong anion exchangers. They are not specific, but selective, which means they do not only remove the main target (NO3-), but also other anions. These are SO4--, Cl-, HCO3-, and even PO4---, among others. These adsorbents exchange the mentioned anions with Cl-. Thats why they are intended to be regenerated with NaCl: Na+ will pass the sorbent during regeneration, Cl- will be exchange by NO3- (and other anions) -> NaNO3 (in solution) is flushed out of the sorbent during regeneration (as well as Na2SO4, NaCl, etc.).
If you use NaOH for regeneration, OH- instead of Cl- will be realeased into the tank which will 1) raise the pH in your tank and 2) lead to an asymmetry between H+ and OH- and access OH- will raise the conductivity AND THE pH! Thats not what you intend, is it?

Since also HCO3- is exchanged, it is clear that you register a drop in KH.

You should keep in mind that the use of nitrate sorbents "contaminate" your tank with Cl-, which is just the lesser evil than nitrate. Dont forget about the regular water exchange in order to reduce the Cl- concentration
and to keep your water as natural as possible.


Recommended reading:
T. Nur, M.A.H. Johir, P. Loganathan, S. Vigneswaran, J. Kandasamy: Effectiveness of purolite A500PS and A520E ion exchange resins on the removal of nitrate and phosphate from synthetic water. Journal: Desalination and Water Treatment. 47 (2012) 50–58 (Sept).

Regards,
Jens (working with adsorption in biomedicine for 25 years)

[brewmaster15]

Dear colleagues,
These kind of Purolite adsorbents are strong anion exchangers. They are not specific, but selective, which means they do not only remove the main target (NO3-), but also other anions. These are SO4--, Cl-, HCO3-, and even PO4---, among others. These adsorbents exchange the mentioned anions with Cl-. Thats why they are intended to be regenerated with NaCl: Na+ will pass the sorbent during regeneration, Cl- will be exchange by NO3- (and other anions) -> NaNO3 (in solution) is flushed out of the sorbent during regeneration (as well as Na2SO4, NaCl, etc.).
If you use NaOH for regeneration, OH- instead of Cl- will be realeased into the tank which will 1) raise the pH in your tank and 2) lead to an asymmetry between H+ and OH- and access OH- will raise the conductivity AND THE pH! Thats not what you intend, is it?

Since also HCO3- is exchanged, it is clear that you register a drop in KH.

You should keep in mind that the use of nitrate sorbents "contaminate" your tank with Cl-, which is just the lesser evil than nitrate. Dont forget about the regular water exchange in order to reduce the Cl- concentration
and to keep your water as natural as possible.


Recommended reading:
T. Nur, M.A.H. Johir, P. Loganathan, S. Vigneswaran, J. Kandasamy: Effectiveness of purolite A500PS and A520E ion exchange resins on the removal of nitrate and phosphate from synthetic water. Journal: Desalination and Water Treatment. 47 (2012) 50–58 (Sept).

Regards,
Jens (working with adsorption in biomedicine for 25 years)

Welcome to SimplyDiscus Jens!

Thank you for adding your experience to this thread!
Are you a fish keeper!

Al

[Tschens]

Welcome to SimplyDiscus Jens!

Thank you for adding your experience to this thread!
Are you a fish keeper!

Al

Thx. Yep, since my early childhood I had one or more aquariums without interruption. But I am not a discus guy, currently I have one 540L Malawi tank.

[brewmaster15]

Well I am glad you found us and hope to see you posting again.
We have a few members that are currently African cichlid keepers.

[danotaylor]

Welcome to SD Jens! I am an avid aquarist. I have keep pretty much everything available in the hobby over the last 45 years. Currently keeping a 110gal tropheus tank and a 500gal Malawi display.
Which African cichlids are you keeping?