Method of selectively removing biuret from urea and compositions for use therein
AssigneeUnion Oil Company of California
InventorsDonald C. Young, James A. Green, II
Life of this patent
Estimating the term…
Abstract
Biuret is selectively removed from urea by treating the urea in an aqueous solution at a pH above about 12.5 and a temperature between about 0.degree. C. and 100.degree. C. for a period of time sufficient to decompose at least a portion of the biuret. Solid urea compositions containing biuret and a strong base capable of selectively decomposing at least a portion of the biuret when the mixture is dissolved in water are also disclosed.
Claims18
A composition comprising an aqueous urea solution containing at least about 1 weight percent urea, biuret, at least 0.2 N concentration of a strong base capable of producing a pH of at least about 13 in aqueous media sufficient to maintain a pH in said solution of at least about 13, said pH and base concentration being sufficient to reduce both the biuret concentration and the biuret/urea ratio in the said solution at a temperature within the range of about 20.degree. C. to about 65.degree. C.
A composition comprising solid urea, biuret, and at least about 0.2 equivalents per kilogram of urea of a basic component selected from the group consisting of strong bases and strong base precursors that convert to the corresponding strong base when dissolved in water, and combinations thereof, said basic component being capable of producing a pH of at least about 13 in water and being present in said composition at a concentration sufficient to decompose at least a portion of said biuret and produce an aqueous urea solution having a biuret/urea ratio less than the biuret/urea ratio of said composition when said composition is dissolved in water and maintained at a temperature of about 20.degree. C. to about 80.degree. C. for at least about one hour.
A composition comprising solid urea containing biuret and a member selected from the group consisting of mineral and organic bases, and at least about 0.4 equivalents per kilogram of urea of a member selected from the group consisting of sodium and potassium hydroxides, and hydroxide precursors, and combinations thereof.
A method for reducing the biuret content of urea containing biuret, which method comprises contacting said urea and biuret in aqueous solution at a temperature between about 0.degree. C. and about 100.degree. C. for a period of at least about four hours with a strong base capable of producing a pH of at least about 12.5, the concentration of said base being sufficient to maintain a pH of at least about 12.5 during said period and to reduce the biuret concentration and decrease and biuret/urea ratio in said solution.
A method for reducing the biuret content of urea containing biuret, which method comprises contacting said urea and biuret in an aqueous solution comprising at least about 5 weight percent of said urea and at least about a 0.2 N concentration of base selected from the group consisting of sodium and potassium hydroxides and combinations thereof sufficient to produce a pH of at least about 13, at a temperature of about 20.degree. C. to about 65.degree. C. for at least about 10 hours.
Dependencies are inferred from the claim text.