Gary M J Masse: Purification and reconcentration of waste sulphuric acid. C I L, Cushman Darby & Cushman, June 9, 1987: US04671951 (9 worldwide citation)

This invention relates to a process for the production of concentrated sulphuric acid from waste sulphuric acid which comprises subjecting said waste acid to microwave energy for a sufficient period of time to effect production of water vapor, whereby said waste acid is concentrated to a desired deg ...