Activated alumina: Is a high-surface-area, highly porous form of aluminum oxide. It can adsorb gases and liquids without changing its form. It works as a desiccant through adsorption. As air passes through the alumina, the water in the air sticks it and becomes trapped and air that passes through an activated alumina filter is dried out. Even if immersed in a liquid, AA won’t fall apart or soften.

You can restore the original adsorption efficiency of activated alumina by heating it to any temperature from 350° to 600°F (177° to 316°C). When the desiccant is heated as described above, the water stored in it is released. This means that filters with AA can be reused over and over again.