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A question about activated charcoal

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newbie

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Does anyone know why activated charcoal heats up when it's mixed with oil? If I don't want to add any water with my colors, I will mix AC with a bit of olive or avocado oil for my colorant and I've noticed that it will get very warm, almost hot. Does anyone know why?

I have to admit that I thought it was the 18th, so I was going to start the challenge entry thread, when I discovered it was only the 17th. I can't remember how to delete a thread so I had to come up something. I do, however, really want to know why AC heats up.
 

Relle

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Sorry I can't help, I mix AC with olive and have never had that happen, first I've heard of it. Hope someone can help.
 

shunt2011

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I can't help either. I generally mix it with a bit of olive or avocado and haven't noticed any heating. That's crazy.
 

TVivian

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I'm so glad you posted this because I thought I was crazy! I mix my AC in a plastic baggie with oil and have noticed it feeling warm to the touch. I have not noticed this when mixing small amounts, but for my swirl soap I used a big, heaping spoonful in a bit of oil and it sure did heat up.


Sorry, I have no idea about why.
 

osso

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My guess is the activated charcoal adsorbs some molecules in the oil, which is an exothermic reaction.
 

not_ally

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I pre-mix my AC in oil in little "master batches" (don't have to do that much of it, since it goes such a long way) b/c it is such a mess to deal with. That may be a way to avoid the immediate exothermicity (if that is an actual word)?
 

galaxyMLP

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I've been thinking about this since I saw the thread post but I cant come up with a good scientific explanation. I'm doing a little online research now to see what I come up with.

I was thinking something along the lines that since some people are experiencing it and others are not, it likely has something to do with the activated charcoal itself. One question though, what are you all mixing the AC in? plastic, metal, ect? I think that may help figure it out.
 

dibbles

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"I have to admit that I thought it was the 18th, so I was going to start the challenge entry thread, when I discovered it was only the 17th."

That's funny Newbie - I thought it was the 16th. Need more coffee!
 

Seawolfe

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Are you saying that the charcoal gets hot with just the oil? Or when added to the lye with the oil?

If you mean the lye, it would kind of make sense, sugar is mostly carbon, charcoal is all carbon, maybe theres just a lye - carbon reaction. If you mean with the oils then I have no idea...
 

TVivian

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Are you saying that the charcoal gets hot with just the oil? Or when added to the lye with the oil?

If you mean the lye, it would kind of make sense, sugar is mostly carbon, charcoal is all carbon, maybe theres just a lye - carbon reaction. If you mean with the oils then I have no idea...

Mine warms up with just the oil. I put about a tablespoon of sweet almond oil in a plastic bag, scooped in a tablespoon of AC, zipped the bag, walked away.. When I came back the bag felt like I had microwaved it. I thought I was crazy.

I wish I had an infrared thermometer so I could do and experimental video.
 

Seawolfe

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Ok thats wild and I have no idea whats causing that.

Mine warms up with just the oil. I put about a tablespoon of sweet almond oil in a plastic bag, scooped in a tablespoon of AC, zipped the bag, walked away.. When I came back the bag felt like I had microwaved it. I thought I was crazy.

I wish I had an infrared thermometer so I could do and experimental video.
 

galaxyMLP

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Acording to wikepedia there are 2 types of activated charcoal formation:


1. Physical reactivation: The source material is developed into activated carbons using hot gases. Air is then introduced to burn out the gasses, creating a graded, screened and de-dusted form of activated carbon. This is generally done by using one or a combination of the following processes:
Carbonization: Material with carbon content is pyrolyzed at temperatures in the range 600–900 °C, usually in inert atmosphere with gases like argon or nitrogen

Activation/Oxidation: Raw material or carbonized material is exposed to oxidizing atmospheres (oxygen or steam) at temperatures above 250 °C, usually in the temperature range of 600–1200 °C. These temperatures produce an instant water-gas reaction, gasifying the carbonized material.[13]


2. Chemical activation: Prior to carbonization, the raw material is impregnated with certain chemicals. The chemical is typically an acid, strong base, or a salt [14] (phosphoric acid, potassium hydroxide, sodium hydroxide, calcium chloride, and zinc chloride 25%). Then, the raw material is carbonized at lower temperatures (450–900 °C). It is believed that the carbonization / activation step proceeds simultaneously with the chemical activation[clarification needed]. Chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material.
If this is indeed the case, it may be that people who are getting heat forming have the chemical activated carbon. This may mean they have excess chemical activators that may be reacting with the oils. Although, it would be unlikely for the KOH or NaOH not to be reacted out during the heating process just with moisture in the air. But, if there is an excess, it could (theoretically) react with the oils in some way.

Can you test the pH of your AC in a bit of water?
 

galaxyMLP

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The carbon is able to adsorb some molecules in the oil. It is called heat of adsorption.
This is true as well. The the part that confuses me is why do some experience it but not others? I tried looking some of that up. I would also be very surprised with how hot they are saying some of their solutions got. Maybe that plays a role but is not the whole story?

I'm just thinking out loud here.

ETA: How much AC do you use to oil? If you use alot of AC to oil or the other way around (alot of oil to AC) that may explain the discrepancy.

This is an interesting article:
http://www.lenntech.com/library/adsorption/adsorption.htm
 
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newbie

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I used bamboo AC but I don't know how it is activated. I generally add a fair amount to a small amount of oil and that is when it gets hot, so it doesn't have anything to do with the lye. I have also noted that charcoal added to batter will thicken the batter more than other colorants and similar to TD- both AC and TD colored batter will be thicker than batter colored with micas. That I assume is from it absorbing water. My recall is that black or white batter cups are warmer than the others, so that holds with the absorption theory. I would never have thought it would produce that much heat though.

I mix my colors in paper cups, like Dixie cups, that are wax coated.

Well, I do thank you for the info about the activation process and the absorption explanation. TViv and I were trying to hide the fact that we were losing our marbles.
 
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