Sciencemadness Discussion Board

Baboon requires Assistance regarding Testing a Process

aga - 27-6-2015 at 13:09

I wish to know how to make my own Activated Charcoal.

Not just Charcoal, but 'activated' charcoal.

A brief discussion with CHRIS25 came up with pyrolysing wood, which so far has presented no problems:-

Make a fire, stuff wood in a tin with small holes in the lid, put tin on the fire, wait until the exiting smoke dies down then semi-seal the holes with a wet cloth.

As far as i can make out, 'activated' charcoal simply has much more surface area than unprocessed
charcoal.

The 'activation' step seems scantily described on the web.

Most mention treating powdered charcoal with CaCl2 (some say ZnCl2) for 24 hours, wash, then dry in an oven to magically obtain 'activated' charcoal.

The best i can glean is that the CaCl2 somehow makes more holes in the carbon matrix, thereby increasing the surface area dramatically.

Not understanding anything of how that might work, i'd like to have a Procedure by which i can test how 'activated' my charcoal is, without using Iodine, as i only have about 1g of I left.

Armed with a testing procedure/protocol i can try out any idea and measure the results.

So far i have come up with this :-

Prepare a charcoal formulation.
Put around 1g sample of the powdered product in a small plastic pot.
Weigh the sample pot & contents to 0.01g.
Put the sample pot in a tupperware container.
In another pot place some TCCA and a stoichiometric amount of HCl to produce around 5g of Cl2 then place it in the tupperware container.
Put the lid on (not quite sealed)
Wait for about 2 hours.
Remove and re-weigh the sample pot to see how much Cl2 the sample adsorbed.

Are these just the ramblings of a fermented banana crazed baboon, or would this not give an indication of how 'activated' the carbon sample was ?

All thoughts appreciated.

[Edited on 27-6-2015 by aga]

blogfast25 - 27-6-2015 at 13:38

Have you any idea how much absorptive capacity any non-baboon produced active charcoal is supposed to have? This here primate doesn't. And yet therein lies the answer to your question: will your method be accurate enough (0.01 g, 'signal to noise ratio' and all that)?

Otherwise absorbing some Cl gas onto baboon activated charcoal is as good a test as any other, I guess...

[Edited on 27-6-2015 by blogfast25]

aga - 27-6-2015 at 13:54

There is this thing called an 'Iodine test' that the Gibbons do as a kind of primate standard for 'activated carbon' generally.

They won't share anything about that unless i give them at least 24 bananas a month, which is partly why i want to Baboon-up some activated charcoal myself.

For reference i bought some Chinese activated carbon filters from e-bay(boon) which should get here in a few weeks, via the grapevine.

14 coconuts including postage !

[Edited on 27-6-2015 by aga]

blogfast25 - 27-6-2015 at 14:19

Spoken like a true chimp. Bear in mind iodine's considerably higher MW and propensity for forming slightly strange complexes (see e.g. starch/iodine). In 'mol/g', Cl absorption may be lower for Cl.

Also, check thermo-reversibility: try and desorb at 200 C or so, without setting fire to the charcoal (it's how these hominids discovered flame wars, the b*rstools!)


[Edited on 27-6-2015 by blogfast25]

zed - 27-6-2015 at 14:30

Nah. Use yer semi-prehensile thumbs, and crack and eat some almonds. Hang on to the shells; they are useful. Make a mighty fine activated charcoal.

http://pubs.acs.org/doi/abs/10.1021/i300014a019

aga - 27-6-2015 at 15:13

Cheers for the Link !

Looks good.

I'll have a good scratch over that.

Edit :

One of my thumbs is always opposed to everything i want to do.

[Edited on 27-6-2015 by aga]

Sulaiman - 27-6-2015 at 16:24

noob level info;

'active' charcoal = 'decolourising charcoal'
you could measure how much methylene blue (or similar dye) it can adsorb ?

Vogel page 128 mentions that common decolourising charcoal is from animal sources but better is from wood, birch is mentioned.

edit: RSC has an introductory experiment using fountain pen ink or potassium permanganate as the dye.

my goto source, Wikipedia under 'activated carbon' https://en.wikipedia.org/wiki/Activated_carbon

by one of the following processes:

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]
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.

[Edited on 28-6-2015 by Sulaiman]

battoussai114 - 27-6-2015 at 19:11

Ok, not long ago I took my baboon questions to the more advanced primates of the university. Seems activated charcoal is prepared by carbonization of material that features an already interesting porosity before the activation... Heard wood, some types of bone and coconut shells make good options. Further more you attack the charcoal you made, on the carbonization, by using some acid or another "harmful" (can't think of a better word) chemical to further increase porosity, lastly you neutralize your charcoal and BAM... SUPER ACTIVATED CHARCOAL, ACTIVATE!.... In the end I got a friendly lab technician to just get me some active charcoal. :D
And it seems that the standard procedure to determine the surface area in the fancy labs over there is through nitrogen sorption/desorption rates.... I'm not so much sure about how this works as I had already bothered those guys too much, and I couldn't risk creating tension between me and the guys who will be responsible for most of my marks.

aga - 28-6-2015 at 00:16

Yes, it is noob level info - welcome to Beginnings !

Thank you for the comments.

Amazing what can be found on the web. James Dewar showed that cooled activated charcoal could adsorb Oxygen from the air, and release 80% of it when allowed to heat up again ! http://rspl.royalsocietypublishing.org/content/74/497-506/12...

Found a procedure for determining the Iodine value using KI :-
http://www.water-chemistry.in/2008/12/determination-of-iodin...

Seems i got lucky by picking a halogen as activated carbon does not adsorb many inorganics.

600-1200 C and superheated steam are a bit beyond what i'm willing to do for this experiment, and no detailed procedure leaps out from any googling efforts, so i'll go with a recipe from ytoob :-

Pyrolyse wood.
Grind the resulting charcoal to a powder.
Make a 25w% solution of CaCl2.
Mix enough of the solution with the charcoal powder to make a paste.
Leave to react for 24hrs
Break up the 'cake' formed, and wash with water.
Heat in an oven for a few hours to dry thoroughly
Grind the product to a powder and store in an air-tight container.

violet sin - 28-6-2015 at 02:32

Did a bit of reading today (and while writing this) since I have long wanted a source for activated carbon(AC) that I didn't have to pay for like others. projects are fun.
The thing that gets me, how do you know it's true potential unless your product was dried at a decent heat under good vacuum? Perhaps it's just my lack of hard knowledge on the subject( and the incredible claims about it's abilities), but with such a high surface area, it would seem(to me at least) that the materials used to activate it would be left adsorbed to the surface unless some drastic measures were used.
----
At least the zinc does stick around.
http://www.newworldencyclopedia.org/entry/Activated_carbon
"This technique can be problematic in some cases, because, for example, zinc trace residues may remain in the end product. However, chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material."
----
Well do the activation temps freely expel the majority of the activation components from chemical activation? KOH was mentioned in a few of my searches, but- wiki-KOH: "Like NaOH, KOH exhibits high thermal stability",.. "boiling pt: 1,327 °C (2,421 °F; 1,600 K)"

So any alkali base would at least need to be washed out with water. I would think that getting rid of water would be hard with so many placed to hide. Almost like dehydrating phosphoric acid to P4O10(lol),.. but fortunately I guess it is easier than that:
-----------------------
https://www.google.com/patents/US4286390?dq=how+easy+is+it+t... Method for removal of water from activated carbon,

In this patent, the author describes a way to get rid of water left from a regeneration process. A ferric chloride catalyst( from their plant process) is entrapped with AC, and is later washed out with water. the water is removed by passing 1,2-dichloroethane(EDC) through the bed to displace 60-80% of the water, noted when the exit stream is water and EDC. The resulting carbon is subjected to either vacuum and heat, or flushing with nitrogen gas( ~18 bed weights N2 heated 100-250'C). capture of the EDC is needed in either case.

they noted commercially available AC has between 10-50mg of water already in it. good to know. also good to know: "It should be emphasized at this time that while more than 80 bed weights of liquid EDC are required to remove substantially all of the water, only about 0.5 to 1.5 bed weights are required to remove 60 to 80 weight percent of the water from an initially water-saturated carbon bed."
---------------------
---------------------------
another water removal method-
Apparatus and method of regenerating an activated carbon filter US 6063272 A
https://www.google.com/patents/US6063272?dq=method+of+removi...
"An activated carbon filter is regenerated while it remains positioned ... then applying an electric current through the activated carbon body of the filter to drive off contaminants."
" A source of direct current low voltage electric current is connected to the opposite ends of the activated carbon filter for a current to pass through the filter and provide both heat and electrostatic stimulus which drives contaminants out of the activated carbon particles. An inert gas such as nitrogen, carbon dioxide or argon may be used to ensure the carbon is not oxidized during the regeneration process"
----------------------------------
also this seems like this might be nice, considering the use of coffee grounds, of which I make copious amounts :)
The production of chemically-activated carbon, doi:10.1016/S0008-6223(98)00174-2 ( in case some one wants to ask for it)
http://www.sciencedirect.com/science/article/pii/S0008622398...
"In an attempt to optimise the microporosity in an activated carbon, controlled heating of sucrose chars and other precursor materials was carried out in an inert environment with an excess of potassium or sodium hydroxide"
"Other precursor materials were also tested... These included coffee ground carbon, macadamia nut shell carbon and... "
----------------------------------
personally, I would have thought carbon suspended in an oxidizing sol( KNO3 ?), drying fast for small crystal growth, then heating to working temp in an inert atmosphere might make porous crude AC. could purge with N2 or CO2(availability) prior to heating, and running butane/propane after the oxidizer has blown it's load of O2, while cooling for positive pressure to limit atmospheric O2 losses during cooking.

another home route maybe something like ammonium nitrate, ammonium sulfate or ammonium acetate to make for a method that would substantially off-gas during higher processing temps. just a couple thoughts thrown out there, with no work testing, so could be total failure.

and I'm done for the night...
also found this, not related at all but cool, microwave preparation of CdS: http://www.researchgate.net/profile/Jerry_Wu7/publication/51...

aga - 28-6-2015 at 14:59

3 AC experiments running now, all with CaCl2 as the 'activator'.

There happened to be a 90um filter screen hanging around so that got used.

Photomicrographs of stuff too, although just x100 mag.

[Edited on 28-6-2015 by aga]

[Edited on 29-6-2015 by aga]

aga - 29-6-2015 at 14:33

The 3 samples got vac filtered and washed 3 times today.

A 4th sample was made using untreated charcoal powder which was also washed 3 times in the same buchner filtration setup.

With any joy i can bake them tomorrow and do the Iodine titrations.

The thing that is confusing in the titration process described here :-

http://www.water-chemistry.in/2008/12/determination-of-iodin...

is this bit :-

"Iodine value: C x Conversion factor; mg/gm

Factor:Mol wt. of iodine (127) x normality of iodine x 40 / Wt. of carbon x Blank reading "

127 is close enough.
Normality of Iodine ? Does that mean the Valence in this reaction ?
Wt. of carbon is presumably 0.2g as stated.
Blank Reading ? The mls of Thiosulphate solution used in the blank titration ?

[Edited on 29-6-2015 by aga]

blogfast25 - 30-6-2015 at 09:16

You seem to have it covered, aga. Look forward to the results and write-up. :)


Big Edit and Ooopsie:

From your linked to protocol:
Quote:
* 0.1N Iodine solution ( 40 gm KI in 1 Ltr of Distilled water ).
* 0.05N Sodium Thiosulphate solution (12.5 gm Na2S2O3.5H2O in 1 Ltr Distilled water)
* 1% Starch solution
* Activated carbon
Procedure:
I Standardisation of Iodine solution
* Take 10c.c of 0.1N Iodine solution in conical flask.
* Add 2 drops of Starch solution.
* The pale yellow colour of Iodine Soln turns Blue.
* Titrate with 0.05 N Sodium Thiosulphate till it becomes Colourless.
* Burette reading corresponds to blank reading.(B)
II
* Weigh very accurately 0.2 gm of Activated carbon
* Introduce it into the Iodine flask which should be completely dry
* Add 40cc of 0.1N Iodine solution
* Shake the flask for 4 minutes and filter it
* Collect the filterate in a dry flask and Titrate 10cc of the filtrate against
Standard Sodium thiosulphate solution using starch as indicator


Unless I've finally turned into a banana, there is something horribly wrong there.

For example, a "0.1N Iodine solution" cannot be prepared from "40 gm KI in 1 Ltr of Distilled water". IodINE is not iodIDE (like KI). Unless an oxidiser is added to oxidise the KI to I<sub>2</sub>, a solution of KI is simply, well, a solution of potassium iodIDE, not iodINE.

I wonder if it's typo and they really meant KI<sub>3</sub> (potassium triiodide), which does contain I<sub>2</sub> (KI + I<sub>2</sub> = KI<sub>3</sub>;) but I doubt it because KI<sub>3</sub> doesn't exist as a solid.

So something is wrong here. And it needs discussing/rectifying or you will be wasting much time and be very SAD. ;)

[Edited on 30-6-2015 by blogfast25]

aga - 30-6-2015 at 13:52

Yes, i can't make head nor tail of the 'procedure' as it doesn't seem to have any internal consistency at all.

It appears to be a re-hash of a side note in a 'proper' paper where they were using FTIR, NMR etc, yet merely indicated (for completeness) the process & math and not much of the practicalities of chemical titration of the 'Iodine Number' of activated carbon.

As far as i've read, the KI is used in an acidic solution to cause Iodine to form I3- and thereby stay in solution.

A discussion regarding better ways to test the 4 waiting samples of supposedly activated charcoal would be most welcome.

[Edited on 30-6-2015 by aga]

blogfast25 - 30-6-2015 at 14:34

Quote: Originally posted by aga  


As far as i've read, the KI is used in an acidic solution to cause Iodine to form I3- and thereby stay in solution.



Without oxidiser to kick I<sup>-</sup> to I<sub>2</sub> that won't happen.

You've three options:

1. Buy good quality I<sub>2</sub>, prepare KI + I<sub>2</sub>, solution 0.1 N (= 0.05 M I2) in I<sub>2</sub>

2. Oxidise excess KI solution with (precise amount of) H2O2 and H2SO4 to I2, solution 0.1 N (= 0.05 M I2) in I<sub>2</sub>

3. Oxidise excess KI solution with (precise amount of) Ferric Ammonium Alum to I2, solution 0.1 N (= 0.05 M I2) in I<sub>2</sub>

In each case except 3., I2 solution will need standardising against Na2S2O3 (as the link correctly suggests).


[Edited on 30-6-2015 by blogfast25]

aga - 30-6-2015 at 15:15

Don't have more than about 1.5g of I2 as it happens.

Got about 30g of KI though, from a very reputable online vendor ;)

Elemental iodine is getting hard to acquire here in the European suburbs.

Sulaiman - 30-6-2015 at 15:17

regarding the testing protocol,
from the tiny bit of research that I have done it seems that different pore sizes are optimal for adsorbing different molecule sizes
e.g. small pores for simple gases, larger pores for dyes etc.
so the 'best' test indicator would be something of similar molecular size to your intended use.
off to the shed now for a quick test using BBQ lumpwood charcoal and methylene blue .....

blogfast25 - 30-6-2015 at 15:22

Quote: Originally posted by aga  
Don't have more than about 1.5g of I2 as it happens.

Got about 30g of KI though, from a very reputable online vendor ;)

Elemental iodine is getting hard to acquire here in the European suburbs.


Got any FeNH<sub>4</sub>(SO<sub>4</sub>;)<sub>2</sub>.12H<sub>2</sub>O?

H2O2?

[Edited on 30-6-2015 by blogfast25]

Sulaiman - 30-6-2015 at 17:26

Iodine; as I posted in this thread http://www.sciencemadness.org/talk/viewthread.php?tid=62731#...
iodine from china via eBay arrived quickly, I'm in UK

Update: Methylene Blue vs. lumpwood charcoal
1) made up a 0.2% (w/vol) solution of methylene blue (MB)
2) ground up some lumpwood charcoal, straight from the bag
3) rough test before main test:
from 50 ml burette added c2ml of 0.2% (c4mg) MB to 5.25g powdered charcoal, NOT decolourised after c5 minutes with stirring.

Abandoned proper test so that I had time to clean up and make better preparations for another go.

. I will cook out moisture and volatiles from the charcoal
. I will sieve out very fine and very coarse charcoal. too fine floats, too coarse may not fully adsorb in a short time
. I will use a more dilute MB solution as 0.2% solution is too concentrated to see through, even in the burette.

so basically a no-result experiment.

Observations;
Methylene Blue vs.
.polyurethane varnish...no stain
.melamine kitchen counter top...stain :( removed with H2O2
.used ptfe burette stopcock...slight stain
.fingers...stain

.running 0.2% MB through burette really shows up any previous imperfect cleaning :P

aga - 30-6-2015 at 23:08

Quote: Originally posted by blogfast25  
Got any FeNH<sub>4</sub>(SO<sub>4</sub>;)<sub>2</sub>.12H<sub>2</sub>O?

H2O2?

Nay, and twice nay (well, got some OTC 3% H2O2).

Looks like i'll have to go shopping.

blogfast25 - 1-7-2015 at 05:16

You'll need 9 % H2O2 (pharmacy, fleeBay).

Ferric ammonium alum is easy to make.