Well, knowing that hydrogen peroxide is a strong oxidizing agent, I assume that it would intercalate with the carbon to oxidize the surface. With subsequent treatment with nitric acid, you would probably simply further oxidize the surface.

Thank you Kimberly. Thats logical answer.

Kimberly, do you think these oxygen moieties are responsible for the adsorption of metals or thiophenes? What is real chemistry involve in such adsorptions? Thanks in advance.

Mohammad,

Absolutely. The surface chemistry of activated carbons are not purely carbon. It contains defects and edges where the heteroatoms, in this case oxygen, are found that have proven to exhibit both acidic and basic properties for adsorption. Depending on the nature of the adsorbate and the functional group present on the carbon determines what you adsorb and the capacity of the carbon. As far as metals, catering your surface with basic functionality (chromenes, ketones, and pyrones) will help increase adsorption. And I think thiophene is more basic so you will want the acidic functionalitys (carboxyl, phenol, lactones).

This can actually be done by catering your activation/oxidation process. Typically, the basic groups resist the higher temperatures of carbonization/activation, whereas your acidic groups do not. You could also try a different type of activation to yield a different surface (ammonia, CO2, KOH). Your carbon source will help tailor these activation process as well by providing a different variation of heteroatom content.

The size and amount of micropores present is an important aspect to keep in mind though. The edges and defects give rise to the micropores, around whose edges are said heteroatoms. If the size of these micropores becomes too large by intense activation, diffusion will work against you and decrease your adsorption capacity.

Hope this helps.

Excellent Kimberly and thanks a lot. Can you enlist any reference(s) for the activation by Ammonia, CO2, KOH.

Again your reply is highly appreciated.

A carbon material can not be converted into activated carbon by a simple treatment in H2O2 or HNO3. Activation is the developement and opening of a preexisting porosity, so rather high temperatures are required (> 450°C for chemical activation; > 700°C for physical activation). Oxidation in aqueous phase produces surface functions playing a very important role in adsorption, but can not called activation. Adsorption and activation are different topics.

Alain