Dieter Gerard & Karl-Werner Quirin 
Dense Gases for Extraction and Refining [PDF ebook] 

Procedures for extracting or refining sensitive substances using dense gases have been developed for numerous purposes. Dense carbon dioxide is already being used industrially for decaffeination of coffee and extraction of hops. Further possible applications have been tested on the laboratory or pilot plant scales and shown to be mostly economical. Uses as varied as the non-aggressive extraction of spice, extraction of polymers, refining of spent oil, pyrolysis/extraction of wood and liquefaction of coal show the extremely wide range of application. The book comprehensively reviews the present state of development and features examples of application of this new technique.