The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 21, 1976
Filed:
Nov. 05, 1975
William Montgomery Hearon, Portland, OR (US);
Cheng Fan Lo, Vancouver, WA (US);
John F Witte, Vancouver, WA (US);
Boise Cascade Corporation, Portland, OR (US);
Abstract
Mixtures of oxalic, meso tartaric, glyoxylic and erythronic acids derived particularly from the oxidation of cellulose derivatives are separated from aqueous solutions in which they are contained and from each other by stepwise precipitation with calcium ion at controlled pH. The oxalic acid is precipitated as calcium oxalate at a pH of 0.9 to 2.0; the tartaric acid as calcium meso tartrate at a pH of 2.8 to 4.4; and the glyoxylic acid, as calcium glyoxylate at a pH of 4.5 to 5.4. After each precipitation the water insoluble precipitate is separated from the aqueous mixture in which it is contained. The relatively soluble erythronic acid remains in solution as a free acid, or in the form of its calcium salt.