adsorbent

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Capable of adsorption.
• noun An adsorptive material, such as activated charcoal.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Tending to adsorb.
• noun The solid or liquid in the process of adsorption on which the adsorbate accumulates.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective having capacity or tendency to adsorb or cause to accumulate on a surface
• noun a material having capacity or tendency to adsorb another substance