An apparatus includes a container that defines an interior. The interior
is isolated from ambient atmosphere for receiving a composition that
includes isocyanate. A conduit extends into the container and defines a
channel therethrough. An interior of the container is in fluid
communication with the ambient atmosphere through the channel for
conveying a gaseous waste stream that includes vaporized unreacted
isocyanate out of the container and into the ambient atmosphere. A medium
is disposed in the channel and has free isocyanate-reactive groups for
reacting with unreacted isocyanate. The free isocyanate-reactive groups
remove the unreacted isocyanate from the gaseous waste stream. The
medium, by including the free isocyanate-reactive groups, relies on a
chemical reaction to remove the unreacted isocyanate.