Recharging GAC and GFO

[peachyman]

so this is 12% h2o2 aka hydrogen peroxide which I buy on Amazon. It's potent stuff so wear good thick pvc gloves. I throw the bagged media in a bucket and swirl it around good. Maybe leave in there a couple of hours then rinse the bags under tap water and walla...it's good for another week. I only do this once then go to new but it may work a third or fourth time. Opinions?

 

[elysics]

How did you determine it is "good for another week"?

 

[peachyman]

Parameters after rerunning it.

 

[elysics]

What parameters are you looking at for gac?

 

[peachyman]

What parameters are you looking at for gac?

Phosphates that don't register on the salifert. I'll eventually get a more sensitive tester.

 

[Randy Holmes-Farley Verified Community Expert]

The peroxide will not impact phosphate bound to GFO. It may remove organic matter from it, and to the extent that organic matter is blocking additional phosphate uptake, it may help (or not) with GFO.

I do not know how effective it is at removing organics from GAC to allow additional organic binding, but it might be.

 

[duffer197703]

Is possible to regenerate with a caustic - NaOH for example, in theory, anyone ever do this?

 

[Randy Holmes-Farley Verified Community Expert]

Is possible to regenerate with a caustic - NaOH for example, in theory, anyone ever do this?

GFO? Yes, it appears that can be partly recharged with base and folks have posted methods.

Aquarium Chemistry: Regeneration of Granular Ferric Oxide Media with Sodium Hydroxide

For aquarists who keep non-photosynthetic corals that require massive feeding, have large tanks, or a dense fish population the costs of regular GFO replacement can be significant. With a few simple tools and techniques we can easily regenerate GFO so that it can be reused several times over.

reefs.com

 

[redfishbluefish]

Back in my day (I'm a dinosaur of a chemist) the only way to regenerate GAC was in a blast furnace.

 

[elysics]

Back in my day (I'm a dinosaur of a chemist) the only way to regenerate GAC was in a blast furnace.

500° C is not going to be enough, is it?

 

[redfishbluefish]

500° C is not going to be enough, is it?

Just looked it up...."The material is heated up to around 1000º F, which volatilizes 75 – 90% of the adsorbed materials. At this point, steam is injected into the system to remove the remaining volatiles and “reactivate” the carbon."

 

[Randy Holmes-Farley Verified Community Expert]

500° C is not going to be enough, is it?

One of the concerns is that if you heat it high enough to burn off organics, you may burn the GAC itself unless you do it in a low O2 environment.

The Care and Handling of Activated Carbon - WCP Online

By Kenneth E. Schaeffer Activated carbon adsorbent media is easy to use and easy to handle. If stored properly, it has an indefinite shelf life. It is nontoxic and relatively nonflammable. If it has become wet or damaged through improper storage, it usually can be dried out or restored easily...

wcponline.com

Activated carbon is combustible, but not easily ignited. In the absence of a forced draft, even hot activated carbon supports combustion with difficulty and, under some conditions, will extinguish on its own accord. However, it should not be subjected to a blast of air at temperatures above approximately 400°F.

 

[elysics]

Just looked it up...."The material is heated up to around 1000º F, which volatilizes 75 – 90% of the adsorbed materials. At this point, steam is injected into the system to remove the remaining volatiles and “reactivate” the carbon."

Huh, a self cleaning oven might almost achieve that. The superheated steam would be a bit risky though

 

[Randy Holmes-Farley Verified Community Expert]

Huh, a self cleaning oven might almost achieve that. The superheated steam would be a bit risky though

Try it on a few grains and see if they are still there after the cleaning.

 

[elysics]

Try it on a few grains and see if they are still there after the cleaning.

I was about to but then it occured to me that it's probably not such a great idea. Wikipedia says palytoxin decomposes at 300° C but I don't particularly want to find out what happens while heating up to that point

 

[Randy Holmes-Farley Verified Community Expert]

I was about to but then it occured to me that it's probably not such a great idea. Wikipedia says palytoxin decomposes at 300° C but I don't particularly want to find out what happens while heating up to that point

I was thinking a new grain from the bottle, but I agree, even if it worked, you probably do not want to.

 

[elysics]

I was thinking a new grain from the bottle.

Sure but I wouldn't be comfortable using the results even if it turned out to work

But I'll report back the next time I'll use the cleaning function

 

[taricha]

Huh, a self cleaning oven might almost achieve that. The superheated steam would be a bit risky though

heh. this is one where the fact that GAC is so cheap really weighs against how I imagine this going.
I think if I volatilize a bunch of aquarium organics in the oven in my kitchen, then it would probably result in bad smells and bad moods. Both of which might linger for an unpleasantly long time.

 

[Cory]

Its so cheap until you add up all the cumulative reef costs lol. Saving money is always a good idea.

Fwiw you can also try microwaving gac.

 

[Randy Holmes-Farley Verified Community Expert]

heh. this is one where the fact that GAC is so cheap really weighs against how I imagine this going.
I think if I volatilize a bunch of aquarium organics in the oven in my kitchen, then it would probably result in bad smells and bad moods. Both of which might linger for an unpleasantly long time.

lol