Activated Carbon Air Filter

This instructable shows you how to make an air purifier to filter pollutants such as tobacco smoke, pollen, solder fumes and many other organic materials out of the air that you breathe.

Step 1 Needed materials and Basic Idea

Computer fan
Activated Carbon
Glue
Window screen
pantyhose
Modeler's plywood
Basswood or balsa
12 volt AC/DC converter

If you have enough modeler's plywood, then you can make the frame out of that, but to save money, I chose to glue my frame together with some balsa wood I had. I had everything but the activated carbon, which you can purchase at pet stores, already at my house.


The purifier works by drawing air through the carbon and forcing it out through the top. The picture below is a cutaway view. The carbon surrounds the purifier on four walls with the fan on the top. The large surface area allows the air to pass through slowly which cleans the air much better.

Comments

[bettablue]

i have found something better than aquarium carbon.

you can buy surgical masks that have a type of active carbon material layered between two needle punched non-woven fabric they are great.

the needle punched fabric filters out dust
and the active carbon material can filter out bad smells
the surgical mask can also filter out viruses and bacteria so it works like a hepa filter! all you have to do is cut of the ear loops and the sides so the pleats open up then you can use it. it costs like £3.00 for 50 masks so it is so cheap and they last for about 1 month.

[csatchell]

This device is exactly what I am looking for, but one question: How do you attach the 12 volt AC/DC converter to the fan wires?

[Crapxxas19]

cut the wire open and solder the + to the red and _ to the black. If you cant tell which is + and - guess and if the fan doesnt work, switch the wires.

[Hatty]

There is just a positive and negative wire coming out of the fan and I hook that up to the positive and negative output of the power supply. Its as simple at that.

[killprogram]

ah yes but be careful when doing so i would recomend getting all of your connections together and semi-permanently fastened BEFORE even plugging it in and i mean i know it is dc but what if the transformer where to break just then? ill tell you what you would have a positivie and a negative end of AC power going from one hand through your chest and heart, to the other

[Hatty]

12 volts isn't really enough to break the skin and get into the body, so there really isn't much danger. But anytime you work with electricity you need to take precautions.

[Wally_Z]

Well, you won't feel 12V. But if the amperage is high enough, it'll kill you if you let it arc across your heart.

[Crapxxas19]

12v cant arc across your body. The resistance of skin is too much. In any normal case, when working with 12v and under it is impossible to shock yourself unless you soak yourself in water for a few days.

[Wally_Z]

If you actually READ what I wrote you will realize that I said "If the AMPERAGE is high enough, it'll kill you if you let it arc across your heart". Bad read^. AMPERAGE IS THE KEY WORD HERE. Google it if you don't know what that means.

[Crapxxas19]

You need voltage for amperage to kill!!!
I have put my fingers across a 12v 5a source and i didnt feel anything. You need at least 40 volts with moist skin to even feel anything.

[Crapxxas19]

Think of electricity like water. If you put your finger at the end of the faucet no water flows. This is like low voltage (pressure of water is low) and no amperage (there is no water coming out.) If you are using a hose, there is some water leakage because the pressure is higher so it means that amps are flowing. Basically you need some voltage to make amperage effective enough to kill.

[GsE-Lance]

30mA kills a person at 230v,
Ampere = Volts/Resistance, in this case 12v / 1000r (resistance of the skin)
Therefore Wally_Z's arguments are invalid.

[jonnybegood]

Yeah yuo are rigth! V=R*I (V=Voltage in volts , R=resistance in omhs and I is current in amperes),WELL this is the OHM Law,and on the other side any DIELECTRIC have a constant, a point that change from not conductor to a conductor(For example the dialectric constant of the air is about 3 Kilovots(3000 vols)...so taht explain the spectaculr pictures of tesla or the ligting)..

[Crapxxas19]

THANK YOU!!!!!!!!!!!!!!!!!!!!!!!!!!
Some people need to know what they are talking about, SERIOUSLY!!!!

[WERNER SLABBERT]

you might actually try three fans in line. say for argument's sake the first fan gives you one bar of pressure, a second in line would double that to about 2.3 bar of pressure and a third would then daouble that to about 4.6 bar. in theory that is.

[XOIIO]

Can you cut charcoal filters, or does all the charcoal stuff come out?

[MrHyde]

for more pressure maybe use this http://www.instructables.com/id/Tesla-turbine-from-old-hard-drives-and-minimal-too/

[chamunks]

I'm curious how you would use this turbine to create pressure or apply the turbine to this.  Maybe I'm just browsing instructables too late at night. 

[lemonshark10]

By manually spinning the shaft of a tesla turbine th opposite effect is acheived and pressure is generated

[junits15]

an extremely more affective way of making an air purifier is to buy a negative ion generator u can get them heresimply put the part with the prongs on it into a continous screen that is wrapped around this. the negative ions attract any type of dirt in the air and cause it to stick to the screen. only downside is that the screen needs to be cleaned every now and then. the negatitave ion generator can also be use to charge a lyden jar! :D

[junits15]

fixed link
http://www.goldmine-elec-products.com/prodinfo.asp?number=G1783

[chamunks]

Broken Link.

[junits15]

damn i hate it when that happens!

[chamunks]

Thank you I definitely appreciate the link fix I will certainly try to incorporate this into something.

Do you think this generator could be used in an ion fan build of some kind.

[junits15]

im not sure if it would work as an ion fan, I've never personally played much with these things (I have a certain fear of high voltages) and I dont know how powerfull one would have to be to generate an ionic wind,  But I wish you good luck anyway!

[chamunks]

amperage is what you need to worry about as long as its not past .87 amps I believe its all good.

[junits15]

yes but its still dangerous, especialy if you have a heart problem.

[JusCoz]

A simple HEPA filter works great, and is a lot cheaper. It also lends a certain interchangability. Cool instructable tho.

[lemonie]

Activated carbon has an affinity for organics, such as the non-prticulate components of smoke. This is less a particulate filter and more an odour / volatile organics filter. I doubt the effectiveness with pollen, but surely both HEPA and carbon could be used. L

[chamunks]

Certainly could use a hepa filter in this equation could always put a hepa filter Just below the fan inside the box this would also help prevent you're fan from catching all the really tiny dust particles. 

But Ideally if someone was concerned about really purifying the air the DIY method, one would use three filters.  

Some reusable/washable filter  Than a Charcoal filter for smell and finally a hepa certified filter for biotic and allergenic issues.

The reusable/washable filter would catch big dust and hair that can significantly shorten the lifespan of you're Charcoal and Hepa filters. 

The Charcoal filter was covered in the comments and article so I wont bother but link you here. The carbon specifically used in this ible was from the looks of it classified as GAC Granular Activated Charcoal.

Finally the HEPA Certified Filter will get rid of airborn pathogens and the rest of the superfine dust.

[Hatty]

That is true. Activated carbon works on organic gases. The only reason I say it works on pollen is because every time my allergies start going crazy, I stick my face in front of the fan on the filter and my problems go away. There is probably another explanation for this, but it works, so I use it.

[Mitten]

Would activated carbon really do anything for the air? It would seem like there would be a lot of gaps around the carbon.

[monterto]

there are a lot of carbon filters out there. they are the most effective filters for the price. the activated carbon doesn't catch particles like a sive, it has a high surface area and a high absorption rate so as particles get sucked through the filter and brush passed the carbon they get sucked into the pores of the carbon. Brita water filters work the same way. this is why they need to be changed periodically also.

[PacoBell]

Actually, don't activated carbon filters operate on the principle of a_d_sorption rather than a_b_sorption? They rely on their high surface area and the material's surface energy. Wikipedia is your friend :)

[chamunks]

You can also aquire a wide range of activated charcoal size grains so from what looks like gravel (used in this ible) to almost a fine powder.  Of course you will have to choose your screens accordingly and airflow can become lessened the finer the powder you choose.

Airflow, Purity, Efficiency,
Its kind of a pick two scenario, you can have any of these two options but you sacrifice the third.

[!Andrew_Modder!]

cant you make carbon??? i saw in a science book you add something to sulfic acid and carbon is made :-\?

[punkhead58]

Um...you can make carbon ash (charcoal) by burning wood, but in this case you need activated charcoal.

[ci857s7]

I dont think you can make carbon, unless you do some nuclear fission or fusion of lighter or heavier atomic nuclei. Carbon is an element.

[!Andrew_Modder!]

oh i remember, if you put sugar into a thing of sulfuric acid, you can make carbon! thats all :-)

[Win7Maniac]

Actually, the carbon is already there; the chemical reaction just separates it and takes it out of the sugar. However, you'd end up with a big, black blob of metal. . . Not much you can or would want to do with that.