Granted Patent
Utility
US 5,137,639 · App. 07/697,547
Method for purifying waste water using surface modified silica
Inventors:
Frederick F. Guzik, Suresh B. Damle, William W. Carlin
Patented Case
View Patent ↗
Granted: Aug 11, 1992
Filed: May 9, 1991
Inventors
Frederick F. Guzik
Suresh B. Damle
William W. Carlin
Assignee (at issue)
PPG Industries, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.