Activated Carbon Air Filter




This instructable shows you how to make an air purifier to filter pollutants such as tobacco smoke, 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
Window screen
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.

Step 2: Make the Frame

This part is critical since it is what keeps your filter from falling apart, so cut and glue well. For the edges of the walls, I used 1/4x1/4 inch strip of balsa. To support the middle, I used 1/8x1/4 inch strip of balsa. Next, make 4 of both the inside and outside walls. You may need to cut some small squares of paper to stick in the corners for extra support.

After the walls dry, lay the window screen out on wax paper. Apply a thin strip of glue to one side of each wall and place onto the window screen. The wax paper will keep the glue, which will run through the screen, from sticking to your table.

After the glue dries, cut each wall away from the sheet of window screen.

Next, cut a 45 degree angle in two sides of the wall so that the four outside and four inside walls can be joined to each other. Make sure that the window screen is on the outside of the square. In the end, you should have two squares with four walls covered and two left open (for the top and bottom of the filter).

Step 3: Putting It All Together

Now that you have the two frames made, you can put everything together. But before you do this, make sure you slide pantyhose over both frames. This will keep the smaller bits of carbon from falling out.

Now, take the bottom part of the filter and glue the frames to it.

While that dries, clean the carbon. During shipping, small bits of dust will fall off. Clean it by placing it in a colander and running water through it. Let it dry and pour it into the filter.

Next, once its full, glue the top on. NOTE: the small hole in the top is used for adding or removing activated carbon after the top is glued on. I just put tape over this to keep the carbon from falling out

If all was done correctly, the fan should fit perfectly into the remaining hole in the top of the filter. Glue the fan in place and you now have a finished air filter.

Step 4: Finish It Up

The white tube on the top of the filter is there to help spread the filtered air around the room. To make it, all you have to do it tape together a paper tube that will fit over the fan. The top is made by cutting vertical slits in the tube and overlapping them to make the paper fold over the top and deflect the air into the room.

To turn it on, you take the two computer fan leads and solder them to the 12 volt power supply. If everything works, it will be very hard to hear it running.

Lastly, if you want the filter to emit a fragrance into the room, it is very simple. Place your favorite liquid fragrance into a thin medicine bottle and tape it to the center of the fan. As the air from the fan passes the medicine bottle, it will pull the fragrance out of the bottle and into the air.

Now, the only problem with the filter is that the air emitted has a slight smell of carbon and I am not sure how to get rid of this. Since the fan cannot develop a lot of pressure, forcing the air through another filter would be difficult. If you have ideas then feel free to email me.



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    101 Discussions


    2 years ago

    This looks great! How long does it usually last before the carbon needs to be replaced?

    1 reply

    Question 1 year ago

    I'm doing this for the sci exhibit but one q though, How would you know if the air is properly filtered?


    Reply 11 years ago on Introduction

    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.


    Reply 9 years ago on Introduction

    You can activate normal carbon, I have done it. You just heat it. you can also reactivate spent activated carbon the same way, it drives off the impurities it has collected.

    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.

    G andK!Andrew_Modder!

    Reply 2 years ago

    charcoal is a fairly concentrated form of carbon, activated charcoal is the filter media... and yes you cam make it.


    1 year ago

    What are the outside measuremnets of the box?


    2 years ago

    Do you have to change the activated carbon regularly?


    2 years ago

    Please share results


    9 years ago on Step 4

    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?

    1 reply

    Reply 9 years ago on Step 4

    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.