Method for removing polychlorinated dibenzodioxin and polychlorinated dibenzofuran and cohesive foreign matter from secondary fibers

摘要

The present invention provides a method for removing sticky foreign matter and / or PCDD and PCDF from cellulose containing fibers such as waste paper. This method is accomplished by contacting the fibers with supercritical or near supercritical propane for a time sufficient to extract a substantial portion of the sticky material and / or PCDD and PCDF without substantial damage to the fibers. The extraction efficiency of up to 95% of PCDD or PCDF and from about 70% to 95% of tacky foreign matter was achieved by the method of the present invention.