DI regeneration reagent strength?

[2thdeekay]

Anyone have an idea what M strength NaOH and HCl is required to regenerate anion & cation DI resin (separate beds)?

I've seen a couple hobbyist protocols for regenerating mixed bed resin--
http://wichitaaquariumclub.com/forums/showthread.php?t=100

They use:
-3 fluid oz (~105 g?) NaOH granules (ryobic) up to 12 oz water, --probably ~7.4 M NaOH
-18% (weight) HCl (Lowes Muriatic @ 1:1 dilution)

Does the NaOH need to be that strong for separate bed anion resin?

TIA! :)

[Randy Holmes-Farley]

The exact concentration is not critical, but it needs to be fairly strong.


This article has more:

http://www.reefs.org/library/article/g_deutschmann_instruct.html

[2thdeekay]

Thanks Randy.

Just wondering if the >7 M NaOH is needed for anion regeneration, or for floating the anion resin from a mixed bed, in order to separate it? Or both?

My resin isn't mixed bed. (The HCl for regenerating the cation resin is ~5 M)

AQUATECHNIC KATI/ANI DE-IONIZER recharging instructions might be helpful, but can't find it.

[Randy Holmes-Farley]

Is there a reason you want to use it less strong?

It may be for floating in part. But if you use it less strong you may need to use more, and I would not want to back off all that much on the strength.

[2thdeekay]

;) I'd just like to know. NaOH is a little more spendy than the HCl. I'm trying to work up an improved protocol than what we found online for some friends.

Separating the anion from the cat with a turkey baster is pretty tedious & inefficient, given other lab/kitchen techniques. Trying to make it less dangerous too. I have a friend/fellow hobbyist who recently almost lost his eye from playing with NaOH. Safety First! Otherwise, reefing might not be as enjoyable/viewable! ;)

Thanks!

[Randy Holmes-Farley]

I do not know exactly what strength is required. I expect it depends on the exact resin and what is bound to it. For example, it may be easier to displace chloride and silicate than sulfate or phosphate.

[2thdeekay]

Thanks. I didn't realize that there are many other recent posts on recharging DI resin. I did a "search" this am. LOL

I have another question. dngspot's recipe calls for letting the separated resins sit in the reagent for an hour. I wonder if that is necessary? Seems to me -OH and +H saturation/ion displacement would occur rather quickly, almost instantly.

The mixed bed resin used by local reefers (perhaps elsewhere too) are Purolite NRW-37
http://www.purolite.com/ProductID/161/FolderID/66/PageVars/Library/Products/ProductDetails.htm
& Resintech MBD-30
http://www.resintech.com/products/frm_ProductInfo.aspx?qProductId=89

Again, I thank you for your time, Randy. :)

[2thdeekay]

I'm thinking I like the NRW-37 better, it seems to have worked better for me (anecdotally). But recently read it's rated ~18 megaohms resistivity, the MBD-30 is rated >10megaohms. The MBD-30 seems to have a better indicator coloring scheme though.

I wonder if there is a better resin for reef use. -Re: life over recharging, etc. I'm not familiar with the spectrapure or other brands of DI resin.

[Randy Holmes-Farley]

FWIW, I do not think the indicator dye is a useful addition. It seems to not change color in time, and impurities are leaking through before the color changes.

[2thdeekay]

Thanks, I agree. I encourage folks to use TDS meters.



:) I found the KATI ANI regeneration instructions, posted by the filter guys:

AQUATECHNIC KATI/ANI DE-IONIZER

KATI ANI 1

REGENERATE KATI

3 LITERS OF WATER ADD .5 LITERS OF MURIATIC ACID

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN KATI FOR 15 MINUTES

RINSE WITH 2.5 GALLONS OF WATER

REGENERATE ANI

3 LITERS OF CLEAN KATI WATER ADD 80 GRAMS OF LYE

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN ANI FOR 15 MINUTES

RINSE WITH 2.5 GALLONS OF WATER

KATI ANI 2

REGENERATE KATI

6 LITERS OF WATER ADD 1 LITER OF MURIATIC ACID

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN KATI FOR 15 MINUTES

RINSE WITH 5 GALLONS OF WATER

REGENERATE ANI

6 LITERS OF CLEAN KATI WATER ADD 160 GRAMS OF LYE
ABOUT ¾ CUP.

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN ANI FOR 15 MINUTES

RINSE WITH 5 GALLONS OF WATER
KATI ANI 5

REGENERATE KATI

15 LITERS OF WATER ADD 2.5 LITERS OF MURIATIC ACID

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN KATI FOR 15 MINUTES

RINSE WITH 12.5 GALLONS OF WATER

REGENERATE ANI

15 LITERS OF CLEAN KATI WATER ADD 400 GRAMS OF LYE

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN ANI FOR 15 MINUTES

RINSE WITH 12.5 GALLONS OF WATER

KATI ANI 10

REGENERATE KATI

30 LITERS OF WATER ADD 5 LITER OF MURIATIC ACID

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN KATI FOR 15 MINUTES

RINSE WITH 25 GALLONS OF WATER

REGENERATE ANI

30 LITERS OF CLEAN KATI WATER ADD 800 GRAMS OF LYE

RUN THROUGH TIME 30-45 MINUTES
RETAIN SOLUTION IN ANI FOR 15 MINUTES

RINSE WITH 25 GALLONS OF WATER