any one know some basic chemistry stuff?

[malulu]

I have a simple question, may be some of you know the answer to?


I have a Kati-Ani unit (to make pure water like RO/DI)...
it comes with 2 Medias....( KATI & ANI )

to recharge - it required to use Muriatic-Acid on the KATI unit, and NaOH on the ANI unit.

when mixing the solution to run through the unit...
it said 1:6 (Acid:Water) run through the KATI unit for about 45+ mins
for my unit #5, it need about 4.5 gals of stuff (can be easily using a regular 5-gals bucket for this task)

QUESTION is:
- i have another set of unit #5 which also need to recharge, due to i don't have a bigger containers...
- can i use the same 5-gals bucket to double it up as 2:6 (Acid:Water) and then run through the unit with 90+ mins (slower drip rate...)
- would it be the same result? or i need to do the same process twice as the dosage as the instruction suggested?
- what about the ANI unit? can i applied the same shortcut to the use stronger NaOH with same amount of water and slower drip rate/

thanks in advance for the great advises to come...



NOTE:
the whole recharging process can be found here:
http://www.njreefers.org/showthread.php?71200-Re-Charging-a-Cati-Ani-unit&highlight=kati-ani

 

[redfishbluefish]

David, I answer with some reluctance. It most likely will work by using twice the concentration for twice the amount of resin……but I’m not 100% sure.


Ion exchange resin beads are typically polystyrene or some “rubber,” such as styrene-butadiene-styrene. For the most part these compounds can withstand the higher concentrations of both acid and base.

What is actually occurring with these resins is that the undesirable contaminant in the water is “exchanged” with either a hydrogen ion or hydroxide ion. (So after the exhange, the output is one H+ plus one –OH….which makes water.) This contaminant is now ionically bound to the resin. Once the resin has been depleted, it’s time to recharge. What the recharge does is to now knock off the contaminant and replace it with either a new hydrogen ion (HCl) or new hydroxide ion (NaOH.) (Note now that what is left after recharging is one Cl and one Na……salt.) This is what you do when you soak or pass either acid or base through the resin respective resins.

What is important with exchange resins are the dwell times and surface area. Dwell time is the amount of time the solution is in contact with the resin and surface area is….well the more the better off or faster the exchange occurs. With you keeping the dwell the same (or slightly more) you are OK there. The one concern I have is whether or not the higher concentration of acid or base would cause the bead (resin) to either swell or shrink. If that is the case, it could impact surface area and change the rate at which the exchange occurs.

So bottom line, I didn’t answer your question. I personally would not change from what the Kati-Ani folks tell you.

 

[malulu]

Haha - Paul,
you did help as always...
l guess i may need to do figure out some other way...?
may be like TWO 5-gals buckets and then put a long hose inside both and reaching the bottom of them ...
with the siphon effect, draining from one will also draw water from the other...

 

[TanksNStuff]

Well, I don't have the chemistry background as Paul, so I can't confirm or deny his undecided answer.

However, I'm looking at this from just a common sense aspect and here's what I think:

I do think Paul was onto something with the dwell or contact time. That seems to be a major factor with the process of stripping the unwanted ions to "recharge" the media. The question I would ask at this point is - Does the ion stripping process dilute or minimize the effectiveness of the acid being used in each container? If so, then simply raising the ratio from 1:6 to 2:6 may not fully compensate for that since it may just be used up faster instead of being usable for double the media.

Basically, I'm wondering if using a higher content would just make the process faster (and still using up the entire active ingredient) instead of being good for twice the recharging?

Again, I don't fully understand the process but to me that's how it seems it would happen. I could be wrong.

That said, I would suggest just to do each Kati Ani recharge separately to make sure that the original process is the same for both units.

 

[Cdiggy]

Watching what people have done on you tube and such they take out the resin and do the treatment (what I used to do back in the day). I don't know if your cartridges are remove able or not but I would think just doubling the recipe and Doing the recharge and rinse in buckets and colanders would be the way to go.

 

[malulu]

1.
i am not trying to speed up the recharge time...

i am restrained by don't have bigger containers... (that can fit on top of my tool-box for recharging)
and wondering can i double up the dosage PLUS slower drip rate to compensate it with the same outcome/effect?

2.
the cati-ani can not be removed from the units.

 

[Cdiggy]

Best bet is to follow the directions of the manufacture as described. Better safe than sorry!

 

[redfishbluefish]

George, the hydrochloric acid and sodium hydroxide are “consumed” during the regeneration process. However note that David is still suggesting using the same amount of acid or base per amount of resin….so the stoichiometry is there.

What occurs (and I’ll only show this little picture example for the cationic resin…but it’s the same for anionic, except it’s sodium hydroxide) is that the acid first dissociates in water….think of free hydrogen and free chloride. The resin likes to bind to hydrogen in acid environments. So the bad and nasty contaminants that were in the water, and now bound to the resin ( the solid black dots) are replaced by the hydrogen ions. The resin has now been recharged….and the hydrochloric acid has been consumed in the process. However, it is there in excess, so no worries about having enough. Once the resin has been recharges, it is rinsed with RO/DI water to get rid of excess acid….. and ready to go.