Frederick Gardner Cottrell
Patent issued (No. 895.729) in 1908 for Frederick Cottrell’s new method for cleaning up smokestack emissions. The method — called electrostatic precipitation — is still used today to remove pollutants from industrial waste flows.
While a professor at the University of California, Berkeley, Frederick Gardner Cottrell (1877–1948) entered the pollution cleanup business because the DuPont Company wanted to eliminate a problem in a process designed to manufacture sulfuric acid. DuPont hired Cottrell in 1906 as a consultant to its facility at Pinole, 20 miles north of Berkeley. The process used to create the acid was producing arsenic that poisoned the catalyst, so Cottrell determined that centrifuging the arsenic-contaminated sulfuric acid mists would remove the arsenic. Then came the problem of precipitating the purified mist. Cottrell experimented with passing an electric charge to the mist globules, which then migrated to the oppositely charged electrode, where they could be collected. This innovation—electrostatic precipitation—also became known as “Cottrellizing.”
In 1907 Cottrell applied electrostatics to a different process. A successful lawsuit filed by Solano County, California, against the Selby Smelting and Lead Company required Selby to clean up its smoke emissions, which were laden with lead and sulfuric acid dusts. Cottrell designed a precipitator to recover the sulfuric acid—again from a mist. Cottrell later installed similar equipment at a copper smelter and a cement factory and developed a related electrostatic process for de-emulsifying oil. The fame of these operations spread, and a presentation by Cottrell at the 1910 American Chemical Society meeting in San Francisco drove home to the world that a major process for cleaning up the air was on the market.
Visit Chemistry in History to learn more about Frederick Cottrell and electrostatic precipitation.
Excerpted with permission, Chemical Heritage Foundation