Method of preparing insoluble hydrolysable tannin and method of treating waste liquid with the tannin
CA 2074796 A1 · Owner: Shirato, Wataru · Inventors: Shirato, Wataru; Kamei, Yoshinobu
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An insoluble hydrolysable tannin is prepared by dissolving a hydrolysable tannin powder in aqueous ammonia; mixing the resulting solution with an aldehyde aqueous solution to form a precipitate; heating the precipitate; mixing the heated precipitate with a mineral acid; and filtering the resulting mixture to leave a residue on a filter. The inventive insoluble tannin exhibits high adsorption properties for heavy metal elements and is insoluble in either water, acid, or alkali. Methods for treating waste liquids and recovering heavy metal elements therefrom using the inventive insoluble tannin are disclosed.
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed July 28, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 28, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 28, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.