This story appeared in the Winter 2020 edition of Plastics Recycling.
A method and system for breaking down contaminated plastics from municipal waste or marine debris is the subject of a patent application from BioCellection Inc., Menlo Park, Calif.
The invention transforms contaminated plastics into products such as dicarboxylic acid and other chemicals. The method involves putting plastic scrap in a reaction vessel, adding one or more oxidizing agents, such as aqueous nitric acid, and subjecting the mixture to heat and pressure.
During the reaction, the contents are agitated, and any vapors that are created are condensed back into liquid. The system can include a separation unit with an evaporator. In some embodiments of the invention, via a screw conveyor, plastic scrap and aqueous nitric acid are continuously added to the reaction vessel and the decomposition products are continuously removed.
Patent application 20190322834; published Oct. 24, 2019