Activating biochar

J Hillman wrote:Adding a very small amount of water to put the fire out helps to partially activate the charcoal.  When real activated charcoal is made they inject high temperature steam into glowing hot charcoal.  The steam, heat and low oxygen levels is what activates it.

John S has mentioned this as well. It's worth its own thread.

I find this difficult because I make most of my char in winter, when its safe to burn large brush piles. I sometimes throw in a little snow to slow the fire down, but I doubt it does the same thing. I guess I could bring jugs of liquid water from the house and add a little to the barrels where I cool and seal the hot char from the air.

I want the final char to be largely dry though, so I can inoculate with stinky stuff during the summer.

Yes, someone had posted a while ago about a chemical means of activating the charcoal.  This process is not the same as charging, inoculating, or nutrifying the char.
My understanding is that it involved puffing it up to make more internal surface area. This makes more "housing for microbes".  It's a topic that is not as well researched and documented as crushing or inoculating the char, but there is some research on it.  I would love to see more.  If I can find that previous thread, I will try to link it here.

I spray cold water on my burning char to put it out.  This process puffs it out for me, so they say.  I can't visually observe the process, so I guess I'm just trusting what researchers have told me.

John S
PDX OR

Here is the previous thread.  As I have not seen a lot of other information on it, I'm not sure if it is in the area of speculation or well documented research. It's an interesting idea though:

"How to Activate Charcoal
Activated Charcoal (also called Activated Carbon) is made by EITHER heating charcoal in temperatures exceeding 600 degrees C (1,100 degrees F) while in a no-oxygen environment (This requires using a special chamber where you can heat up your charcoal in the presence of something like Argon instead of a regular mix of air to prevent any oxidation), OR crushing normal charcoal to a powder, adding an strong acid, strong base, or salt, then heating it again to temps between 250-600 C (400 - 1,100 F) <-- much more accessible!

Recipe for activating charcoal:
> Pickle Crisp - Calcium Chloride - a type of salt. You can buy it in big tubs at most places that sell pickling materials.
> Water
> Charcoal


Step 1: Make charcoal. Then powder charcoal by smashing with a hammer or using mortar and pestle.

Step 2: Be careful, this step generates heat. In a STAINLESS STEEL (not aluminum) bowl;  Make a 25% solution of calcium chloride with water, at a 1:3 ratio.
If you have 600 ml of water you want 200 grams of calcium chloride. You want to make enough of the solution to completely cover the powdered charcoal.
Using tapwater is fine, because the amount of trace minerals in tapwater is basically nothing compared to how much the carbon can adsorb.

Step 3: Add your solution to your powdered carbon, a little bit at a time. You may not use all of your solution - once it reaches a thick paste consistency (like peanut butter), stop adding more solution and just mix the paste until smooth. Get out all the lumps.

Step 4: Cover the bowl with a towel and let it sit untouched for 24 hours to allow the chemical reaction to continue.

Step 5: Drain off the liquid using a coffee filter or very fine muslin cloth. Put the sludge back into your metal pot.

Step 6: Take your pot of nearly-activated-carbon, put the lid back on, and put it into a fire that exceeds 200 degrees C (400 degrees F) - a normal campfire should do the trick. Keep it on the fire with the lid on until it stops steaming, and then take it off to let it cool - don't open the lid until it's completely cool.

Congrats, you’ve activated your charcoal!

WARNING:
When ingested, Charcoal and Activated Charcoal will ALSO bind to medicines in your gut, along with helpful vitamins, minerals, and antioxidants from our food instead of letting the body absorb it. Our bowels pass the charcoal much faster than the charcoal takes to release those nutrients and medicines back to us.

DO NOT ingest activated charcoal within 48 hours of taking, or expecting to take, any type of necessary medicine. Especially antidepressants and anti-inflammatory medications. The charcoal will likely deactivate & adsorb it - or at the very least make it less effective than that dose should be.

Charcoal and Activated Charcoal is not absorbed by the bloodstream. It stays in the digestive tract until excreted via bowel movement. This means it has no ability to remove alcohol from the bloodstream."

Here's the link to the whole thread, which is pretty long, but has a lot of information:
https://permies.com/t/193954/handy-guide-charcoal-biochar-activated

I have never used the calcium chloride version, and as I seem to recall, he mentioned that on my small scale, it might not be worth it.

John S
PDX OR

John Suavecito wrote:Here is the previous thread.  As I have not seen a lot of other information on it, I'm not sure if it is in the area of speculation or well documented research. It's an interesting idea though:

"How to Activate Charcoal
Activated Charcoal (also called Activated Carbon) is made by EITHER heating charcoal in temperatures exceeding 600 degrees C (1,100 degrees F) while in a no-oxygen environment (This requires using a special chamber where you can heat up your charcoal in the presence of something like Argon instead of a regular mix of air to prevent any oxidation), OR crushing normal charcoal to a powder, adding an strong acid, strong base, or salt, then heating it again to temps between 250-600 C (400 - 1,100 F) <-- much more accessible!

Making activated charcoal doesn't' require any special chamber.

Burning charcoal in any type of pit is already in a low oxygen environment.  Any O2 that gets to the hot coal instantly is turned into co2 then the co2 is cracked to co.  So if you blow air into the bottom of the pile to get the coal above a red hot then stop blowing the coal will be well above 1200F and be in a very low oxygen environment.  

Once the coal is in that state the best thing to do would be to add high temperature steam at atmospheric pressure (high temp steam can be made by boiling water in a kettle, running the steam through a pipe that is in a fire and dry, high temp steam will come out the open end of the pipe)

If you can't do that you can splash a bit of water on the hot coals.  The water will flash boil and the steam will be super heated and activate the carbon.  The process of turning the water to steam and super heating it will take energy from the coals.


I have also seen two tests of trying to activate charcoal with calcium chloride that have showed that method doesn't work.

Great perspective, J Hillman.

John S
PDX OR

Do you guys notice a "popcorn effect" when you quench red-hot char?

I haven't visually observed it.  I assume that it is happening on a micro level so I can't see it.  I am just trusting those with higher science understanding at this point.
John S
PDX OR

I concur. I always drench my piles to put them out before it all goes to ash. Never noticed anything visually at the time and since I have never made char without hosing it down I have nothing to compare it to.

To be honest I think I have said I have "activated" my char before under the assumption that it was just another phrase for "inoculating" or "charging". Ooooooooops.