Activated Carbon Production

If it is a 'primitive' (not terribly effcient) application - then start with charcoal produced by the 'barbecue' process, then activate that with steam.

Others might be able to give temperatures etc.

Yes, the etc. is what I am looking for. I have found the temperatures just need to know how to mix the steam with the heat source, possibly a propane burner. The idea is to start with locally produced charcoal, place it in the rotary kiln fire the burner and use the burner to produce the steam inside the kiln while at the same time heating the charcoal without re-igniting the charcoal. It is my understanding that some use either nitrogen or co2 instead of steam. Steam would be cheaper and could be produced anywhere. A rotary kiln could be made fairly easily and even a continous feed kiln where the carbon is added in one end and as the kiln rotates it is tumbled and travels from one end of the kiln to the other and out of the opposite end. The activation process simply opens the pores in the charcoal by removing some of the resins trapped in the pores of the carbon. If it were only that simple.

Surface area is the trick, Start with 'Walnut Shells'

Open a tin-o-beans whatever, but keep the lid attached to the can, Then put tin in fire, with walnut shells and lid closed, watch lid carefully as a flame of producer gas should come out, when the last blue flicker of flame subsides, remove can from fire with tongs and cover tin so no air enters. Allow to cool, and inspect results. Good Luck. (Bigger tin/tube = more production)

It look as if you are producing carbon. I am wanting to activate already produced carbon as mentioned in the reply above.

Rustyh2o

'what is the harm if you can produce activated carbon, your final product directly from the walnut shells instead of using already made chrcoal. I remember a long time ago my company in India made a project of making activated carbon pellets from coconut shells by grinding these and turning these into fine coal under inert conditions and then pelletizing the powder and then processing the pellets to acticate them. I do not really remember how the activation was done, as I was involved in the equipment and not the actual process

No harm but I fail to see how this will produce activated carbon. This using a bean can filled with nut shells has no activation propertities that I see. A way to produce carbon but the pores in the carbon need to be opened as I understand. True wood carbon has a natural iodine number of 100 to 400 I am looking for a cheap way to produce 1000 to 1100 IN. I do safe drinking water development in Africa. Charcoal is usually cheap and plentiful. Countires like Ghana produce coconut carbon and even activate it.

I could always just use more volumn of regular carbon and possibly get the same absorption result

Hi 'rustyh2o' Charcoal from walnut shells, as I mentioned first, has a very large 'surface area'. The old tin can approach is an artist's favourite trick. If the sticks of wood are springy, like willow or vine, then good drawing charcoal results. if the sticks break, so will the charcoal. (a slight digression) At this stage may we assume you are at a pre-production research stage. As our guest mentioned, all sorts of material have been used successfully to produce charcoal suitable for activation. If you dress a wound with activated walnut charcoal, for instance, it has been shown to keep it sterile. Perhaps, I once conjectured, with a gram having a surface area approximating to a football field, the little pathogens got lost in a dark maze?

Where does the activation take place? That is what I am interestd in.

It is the ubiquitous Van De Waals forces, specifically London dispersion force, that makes the carbon 'Active' These forces are often the 'bane' sometimes the 'boon' of those working with nanotechnology. Surface area and nano dimension are the key. i.e. notice how very fine powder 'clumps' together. The 'Dipole Moment' of the H2O molecule may be responsible?

http://en.wikipedia.org/wiki/London_dispersion_force

Here is my goal, production. Developing a simple activation process

this is copiedd from http://www.carbonapelsa.com.mx/pages/english/activation.html

There are two main activation techniques used to produce activated carbon:

Steam Activation - Activation is carried out at high temperatures of 800 - 1000°C in the presence of steam. Initially, gasification of the carbonized material with steam occurs; a reaction known as the Water-Gas reaction. This reaction is endothermic so temperature must be maintained by partial burning of the CO and H2 formed.

Air is added to burn the gases without burning the carbon, producing a graded, screened and de-dusted activated carbon. Activated carbons produced by steam activation generally exhibit a 'fine' pore structure, ideal for the adsorption of compounds from both the liquid and vapor phase.

Chemical Activation - The raw material is impregnated with a strong dehydrating agent, typically phosphoric acid (P2O5) or zinc chloride (ZnCl2) mixed into a paste and then heated to temperatures of 500 - 800°C to activate the carbon. Activated carbons produced by chemical activation generally exhibit a very 'open' pore structure, ideal for the adsorption of large molecules

I would suggest using partial oxidation in a tall column, with air fed to the bottom to initially make the starting charcoal, then adding steam to the inlet, a little off of the bottom to activate the material. Use something like a charcoal lighting tool with two gas inlets, but make it very tall.

Best Regards

Chris

Chemsimman@dynasimtech.com

Basically the heat boils off the volatile hydrocarbons, organic, oxides, etc, leaving behind a rigid microporous structure of molecular dimensions.

The heat would cause the wood/coal/shell to burn away (catch fire) when oxygen is present, so superheated steam is used- because it has no oxygen and is easy to produce.

The porous lattice in charcoal, when in service, fills up with (any molecules of anything that can get in the pores).

It then becomes saturated. And needs replacing/reactivating.

Yes thats it. I dont think it would be that hard to accomplish either. Just need to get the process down to a level that would be productive, cost effective and duplicatable. I would like to develop a system that would produce about 400 pounds or 225 Kilo per day without using tremendous amounts of energy.

Hi, rustyh2o: You might find that an old 'Potters' pug mill, can be salvaged for your purpose, Then a long 'boiler tube' salvaged or new? just might give continuous production. Just wet your material in the hopper feed of the 'pug mill' and you will get all the steam you need. Worth a try, but no guarentees offered Good Luck.

P.S. there are 'issues' with the Zinc Chloride.

please ellaborate on the zinc chloride. What are you talking about? How does that come into play with virtually pure carbon or are you just jerking my chain. i know what a pugmill is. It grinds clay into a workable mass. To get steam you just add water and much heat.

Still the question is how to activate charcoal. Wet carbon does not meet the specs of activated carbon. Sorry but I have had a very large day and know what is needed. Do you have any data to substanitiate what you are saying.

rustyh2o

Sorry about your long day rustyh2o, The suggestion of a motorised clay pug mill, is just a guess, that it would likely be robust enough to continuously feed crushed 'shells' into a heated boiler tube, where heat would carbonise the shells. There is no magic about 'Activated' Charcoal. The structure of the resultant carbon is all important. Chemical activation and other such production methods really apply only to large volume plant, where energy savings etc. are paramount. The London/Van de Waals forces concomitant with an ultra fine porous structure are causative of the so-called 'Activation' ....actually all charcoal is 'active' to some degree or another. Ask any Whisky Distiller?

From Wikipedia:-

1. Chemical activation: is the other method used for the preparation of activated carbons, which involves impregnation with chemicals such as acids like phosphoric acid or bases like potassium hydroxide, sodium hydroxide or salts like zinc chloride, followed by carbonization process at temperatures in the range 450-900ºC. It is believed that carbonization and activation step proceeds simultaneously in chemical activation. This technique can be problematic in some cases because, for example, zinc trace residues may remain in the endproduct. However, chemical activation is preferred over physical activation owing to the lower temperature and shorter time needed for activating material.

The source material can be several carbonaceous materials, e.g. nutshells, wood, coal.

Postscript:- If you fed a 'sausage' of wet crushed walnut shells into a red hot boiler tube, the moisture will turn almost instantly to superheated steam. There is no wet carbon/charcoal extruding from the end of the boiler tube, just a whole lot of 'producer gas' that might help to heat the boiler tube. I made a plant much like this in Kenya in the 1970's but because it was too complicated to plumb the gas back, we just burnt it off, a six foot flame at that. looked good at night. The boiler tube was salvaged from an old steam locomotive, most were used for cattle grids. The boiler pipe fixed into a 40 gallon tar barrel [cleaned] which had a clip-on lid. The giant Bunsen burner was plumbed onto the lid. It was important that the extruded 'sausage' diameter was slightly smaller than the Inside Diameter of the boiler tube, so as to allow the producer gas to vent. This project was also for water purification. When you are 250 miles out in the wild, you make do with what you can find. Everything is recycled. I have fond memories of tinkers who used to ply a trade 'mending old tin cans' the ones we throw in the trash bin. When past repair, they would purchase the worn out 'Kimbo' tin and tinker the steel into a 'Wok'. or 'Calabash'.

Thanks for the good info. I will study it this evening when I have more time.

At a guess, zinc chloride could be used (as could numerous other salts instead) to dose the carbon to make special gas mask filters to protect against specific contaminants. This is a highly specialised process.

The carbon soaks up the gaseous contaminants from the air passing through the filter to the lungs. The contaminants then 'condense' in the carbon and get neutralised. The salts get 'consumed' in the process. The carbon cannot be reactivated.

Water purification is quite different. You are simply removing molecules of (whatever) from the water and these get trapped in the carbon until saturation is reached. Water molecules also get trapped but because of differential forces at play the water gets displaced from the carbon - leaving the contaminants behind.

This is reversible by reactivation - but probably not economical.

That is interesting. How about silver nitrate. It is used to treat carbon used in water filtration. I am interested in dosing the carbon and then heating in a reduced atmosphere to drive out the salts and leave the silver un-oxidized. Silver has a better bacteriostatic value that silver oxide. Any suggestions on how to accomplish this. I could even do small batches of 3 kilos if possible. I do know that potters use certain chemicals placed in a can in the kiln to maintain reduction, some which are toxic.

I cant help beyond this point. I (we - the company) use activated carbon to remove toxic contaminants from compressed air for breathing in respiratory protection products. Pore size, granule size, packing density, all come into the equation.

We therefore use ready made carbons that we obtain from commercial sources. This is essentiasl for us because we rely on our suppliers to provide carbons that are manufactured under strict quality control conditions. Our suppliers also have to provide traceable health and safety data. We do not use enough to justify a DIY approach.

Anything I have told you above is based on info picked up over the years - as a user - but not as a manufacturer.

I know adding silver traditionally bumps the price up (blamed on the cost on the cost of silver). Usually the silver improves performance - but I guess in your case you can get the same performance by chucking in another shoveful of carbon. This is not possible with gas masks because weight is a serious problem.

Good luck!

thanks, I will continue researching this. I have bought samples of carbon that was treated with silver nitrate. It was about 5 x the cost of regular coconut shell carbon.

I am sure there is a simple way to do this just have to find it. The manufacturers are secretive of the process and I cant really blame them. They are making money. I am just working at giving 1.1 billion people some relief from contaminated water. In the past I have worked with different mesh sizes of ceramic material for filtrarion.

My goal is to develop water filtration that can be easily duplicated in the field. Charcoal is easy to crush and screen I just need to get this step of the process worked out. It might be as simple as using steam or carbon monoxide to provide a low o2 atmosphere for reduction.

Good Luck with the project rustyh2o you clearly have a 'Big Heart' I would myself be cautious about introducing silver nitrate, especially with the X'5' cost penalty. Native silver ore is occasionally fibrous, so you might be able to incorporate some of that?

Another possibility is the old formula for the 'Silver Mirror' test for Aldehydes and Ketones, a 'fulminated solution of Silver', (Titrate ammonia into Silver Nitrate Solution, first the solution goes cloudy, then one drop makes it clear again, CAUTION....It's EXPLOSIVE when dry!....in an Aldehyde solution fulminated Silver will deposit Silver on the side of the Glass Test Tube)......If you are in the mood to experiment, perhaps Glass Fibre Woven Fabric could receive a coat of pure silver just the same way? i.e. That could be incorporated into your filter.

The X 5 cost is for vendor produced charcoal with silver. The dosing process is fairly simple and Stepwise, add 1.57 grs. silver salt to 1.2 liters of tap water. At this rate it would still be affordable. I have contacted some potters about what they use to keep their kiln in reduction. One recommended raw carbon. Well that is what I am working with except for the silver. I have some work to do concerning a vessel to heat the carbon in evenly to 600c. That is what is recommended to drive out the nitrates.

Then there is ionic silver. I have built a generator for that. It takes a while to run a batch.

When I want some 'colloidal' silver, all I do is bung scrap silver from the local jeweller, into a beaker of nitric acid (fume cabinet job) just leave as much to dissolve as possible, this may take a day or two. Then I strip some copper flex, scrap(household mains) and give the copper a jolly good polish, with a household brass polish, ..it leaves a thin protective layer designed to retard oxidation...then I just make a 'whisk' and whisk up the silver nitrate solution, Silver just flies off the whisk, and settles rapidly to the bottom. A cheap and cheerful solution. don't know if it's any use to you rusty? but is ever you want a conductive paint/cold epoxy solder, it's one way of doing it.

oops sorry rusty, forgot to mention diluting the silver nitrate solution before whisking. (health and safety considerations apply here, so read the nitric acid data sheets) BTW I once thought ultrasonics i.e. transducers in a pipeline, might be a way to set up a continuous production line. The chemistry is fairly basic.and the acid would regenerate to some extent. pollished copper plates in the pipeline adjacent to the ultrasonic transducers, or the transducers attached to an internally pollished copper pipe,....might work? ...Merry Christmas. and a Happy, Healthy & Prosperous New Year.

one very old process for production (not actuality use, very poor) for activated charcoal is by burning bones

Silver(I) oxide -- Ag2O -- decomposes to silver metal and oxygen at 230 deg C (446 deg F). I don't know if anyone has used this approach to dope activated carbon with silver, nor do I have any idea of the cost. But this sounds like it could provide a clean way to accomplish your goal, assuming the temperature would not be a problem.

How very interesting svengali, now I wonder if a pulsed laser could restore old tarnished silver and silver plate? Coin collectors might be interested? Only the oxide would be heated, so the temper of the unoxidised metal might not be affected, Nothing ventured, nothing gained, as they say.

Heating tarnished silver with a laser probably would decompose any silver oxide back to silver. But -- contrary to what most people would guess -- the black coating on tarnished silver consists mainly of silver sulfide (Ag2S), not silver oxide. The sulfide is more stable, requiring much higher temperatures to thermally decompose. Any in any case, the chemical tricks used to clean silver are very easy and inexpensive. But the laser method sounds worth a try? Maybe patentable.

You are perfectly correct. If you leave silver plate cutlery soaking in a washbowl with egg soiled plates for too long, expect to see blackened silver from the egg's sulfur content.

As for patentable? Not in the UK. as our Patent regulations require non-disclosure. I once asked an official at our Patent Office if a conceptual project was patentable. His reply was very apologetic, "I am sorry, but the patent would be invalid if you disclosed it, even to me, You must make a declaration of no prior disclosure on your application form, and that even includes inadvertent disclosure to staff at the Patent Office itself, we would not be able to accept the application, and you could be sent to prison for making a false declaration, if you failed to disclose the information you inadvertently revealed to us at the Patent Office."

Wonderful, we Brits are almost as good as the Portuguese, when it comes to bureaucracy, (CAVEAT)

LOL! Unbelievable! That reply from the UK Patent office sounds like a comedy skit straight out of Monty Python's Flying Circus. Do those patent office workers get around the problem by wearing blindfolds while they process the no disclosure forms?

Leo

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"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." -- Bertrand Russell, philosopher, mathematician, author, Nobel laureate (1872-1970)

What has been said by Alastair is correct. I am not a patent expert but I have been through the mill. I got a patent for a compressed air breathing purifier 22 years ago (it has long expired) - this is where activated carbon comes into it.

It might sound incredible but the patent officer did warn of the problem, and in practice he would not see the documents until after the application had been filed.

It is fundamental to the process that a patent can only be granted if an invention is novel - and it it difficult to prove that you have invented something if the whole world knows about. Especially before the prior date of the application.

So you don't tell anybody. But you are allowed to discuss it with professional advisors - solicitor, accountant, patent agent - who in turn should be telling you to get the idea lodged in writing and dated.

The existence of prior knowledge when you apply does not worry the Patent Office too much - because they will discover that very soon in their search - but if you are lucky and they don't find anything, they might grant a patent.

However, you are at commercial risk, because if there is prior knowledge, and if at a later date your competitors copied your product, your patent will give little or no protection (against competition) if they can prove that their design was based on knowledge that existed before you got your patent.

But being sensible, your competitors would not be able to 'win' their case simply by producing evidence from within their own knowledge base ("...we have known this for years but we have only just got round to making it...") - they would have to show that you knew as well - and that might be difficult to prove (unless you worked for them perhaps...!). No, they have to show it was general knowledge at the time - like here, being discussed on the internet

I think it is clear that keeping it 'secret' is the best approach.

Thanks Horace,

Well put, there is definitely 'method' in the apparent 'madness'.

some process for production off activated Charcoal use inorganic acid (sulfuric or phosphoric) after the steam activation for father activation and salt removal

not all poisons present in the water can be removed with activated charcoal, for example Arsenic. Arsenic can be remove from water with iron oxides and activated charcoal, ie, char and iron rust chips.

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