Activated Carbon In Filtration

After a conversation with Mark P last night regarding activated carbon, I thought that I would offer some explanation and maybe clarification, IME, on the subject.

"Activated Carbon" is an organic that has been particulated and fractured. There are many forms of activated carbon, and some work better for targeted contaminants than others. How is it activated? The particulates are rapidly heated then rapidly cooled which caused small fractures in the particulate which increases surface area.

Activated carbon works on ADsorbtion. Matter and contaminants are trapped on the and in the surface area. For instance, activated carbon quickly and effectively removes chlorine from water.  The presence of organic matter in water can cause color, taste, and odor complaints. Activated carbon adsorbs organic matter in its extensive network of pores. The adsorption process takes time.

Synthetic organic chemicals (SOC) include all man-made organics, some of which are volatile organic compounds (VOC). Activated carbon can substantially reduce many VOCs such as benzene, trichlorethane, and carbon tetrachloride. Activated carbon also removes SOCs such as Alachlor, EDB, and toluene as well as a host of other metal contaminants, etc.

Activated carbon beds compact with use so they may need occasional backwashing. In general, however, backwash carbon when the pressure difference between the filter inlet and outlet increases by 5 - 10 psi (34 to 68 kPa) from the beginning of the filtration cycle. When operating a carbon filter on turbid water supplies, remove suspended particles with a pre-filter before treating it with activated carbon.

Over a period of several months to years, the carbon's adsorption capacity diminishes, which means that the pores of the media become impacted and cannot contain any more contaminants. The exhausted carbon bed should be replaced with fresh carbon.

  Hope that this helps someone somehow.

LOL... Thanks for the scientific input JF! I did know that GAC actually reacted to/with chlorine, but wanted to dig a bit into the myth that it was very short lived as filtrate. It is quite effective as a media and has significant longevity. Adsorbtion is probably it's largest role in filtration, I am sure that you would agree. I must say though, not thrilled with the Culligan Man reference.

Sean, what it means is that GAC is a good thing. It's truly beneficial to a filtration system, although maybe not necessary in many setups. Don't fear the carbon!

jfinch wrote: OCl-        +          C          =          CO2       +         Cl- chlorine          Activated              Carbon           Chloride Ion (as chlorate)    Carbon                Dioxide           (harmless)

  I seem to have messed up the equation (that's why I graduated in chemical engineering, not chemistry ).  Thanks Gonzo for seeing that!  I'm glad someone was actually looking at it...  It should be:

2 OCl-     +    C    =     CO2    +    2 Cl-

How long do you leave it in for?  Do you use it passive (in a sock in the sump) or active (in a canister with pumped water passing through)?

Let's talk about the petroleum industry again...

Ya, what the h*ll does an oil man know about water anyway?  Let's change the topic... Anyone know what the "R+M/2" octane rating on the gas pump means?