Influence of pore size and surface functionality of activated carbons on liquid-phase molecular adsorption behaviors was carefully investigated both in terms of adsorption capacity and kinetics using indole and amylase as model adsorptive bio-materials by individual single-component experiments to improve adsorptive removal efficiency and selectivity of body wastes. Activated carbon fibers having narrow pore size of about 0.65 nm showed the highest adsorption capability of indole per unit surface area. From the point of view of the adsorption rate, however, a little bit wider micropores of about 0.70 nm considered to be preferable. It was also confirmed that a presence of oxygen-containing surface functional groups induces diffusional inhibitions of indole molecules to deeper pore spaces, giving rise to a lowering both of adsorption capacity and rate of indole. On the other hand, amylase adsorption amount was limited for microporous carbons. Therefore, as for oral applications to selectively remove the wastes in the body such as indole but not for useful molecules such as amylase, the activated carbons having abundant micropores of about 0.7 nm in size and hydrophobic surfaces were found to be suitable from the individual single-component experiments.
Keywords: Activated carbon, Adsorption, Bio-molecule, Pore size, Surface functionality