Abstract: A process that removes chlorine or other halogens from plastic mixtures by passing a plastic mixture through an extruder, a mixer, and one or more devolatilization vessels.

Abstract: Processes and apparatus are described for removing impurities from solid biomass while preserving hydrogen and carbon content. Examples are provided of processes using acidified aqueous solutions in a countercurrent extraction process that includes the pneumatic transport of slurries between process units, or a mechanical dewatering step, or both, to produce a washed biomass suitable for various upgrading and conversion processes. Compositions related to the processes are also described.