Activated charcoal and zeolites are both categorized by having pores equal to or smaller than what size?
Activated carbon Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. "Activated" is sometimes substituted with "active".
Cigarette filter A cigarette filter is a component of a cigarette, along with cigarette paper, capsules and adhesives. The filter may be made from cellulose acetate fibre, paper or activated charcoal (either as a cavity filter or embedded into the cellulose acetate). Macroporous phenol-formaldehyde resins and asbestos have also been used in cigarette filters. The acetate and paper modify the particulate smoke phase by particle retention (filtration), and finely divided carbon modifies the gaseous phase (adsorption). Filters can reduce "tar" and nicotine smoke yields up to 50%, with a greater removal rate for other classes of compounds (e.g., phenols), but are ineffective in filtering toxins such as carbon monoxide. Most factory-made cigarettes are equipped with a filter; those who roll their own can buy them from a tobacconist.