Abstract: The present invention is a method of stabilizing hydrogen peroxide in an aqueous solution, such as a circulating water slurry, comprising a peroxide, such as hydrogen peroxide. The aqueous solution may include organic matter. The method comprises adding an aldehyde donor, such as a methylolhydantoin, to the solution (or slurry). The inventors have discovered that aldehyde donors significantly reduce the decomposition of hydrogen peroxide by catalase and other peroxide decomposing enzymes, which are often present in recycled paper. As a result, less hydrogen peroxide needs to be added to a solution to effectively bleach organic matter in the solution. Furthermore, aldehyde donors are safe to handle and cost effective. Another embodiment is a method of bleaching recycled papers in a circulating water slurry comprising organic matter. The method comprises adding hydrogen peroxide and an aldehyde donor to the slurry.

Abstract: A highly stable liquid formulation having broad spectrum preservative properties which constitutes an admixture of a dialkanol-substituted DMH, an iodopropynyl compound, a stabilizer of a hydantoin, urea or derivative thereof, and a hydroxyl solvent. Preferably the constituents are dimethyloldimethylhydantoin, 3-iodo-2-propynylbutyl carbamate, dimethylhydantoin, and a glycol solvent. The preservative preferably has a total formaldehyde content of 5% and less than 0.2% of free formaldehyde. The composition is prepared by successively admixing the dialkanol-substituted dimethylhydantoin and the stabilizer, the hydroxyl solvent, and the iodopropynyl compound. Also described is a stabilized iodopropynyl compound preferably containing dimethylhydantoin as the stabilizer.

Abstract: The present invention provides a highly stable formulation having broad spectrum preservative properties. The formulation is an admixture of dialkanol-substituted dimethyhydantoin, one or more isothiazolone compounds, a hydantoin stabilizer, and a hydroxyl solvent. The formulation is highly stable in pH ranges of about 4 to 8. Preferably the active components are dimethyloldimethylhydantoin, chloromethylisothiazolone and methylisothiazolone, and the stabilizer dimethylhydantoin. The formulation has a free formaldehyde content of less than 0.2% and is beneficial for preserving various aqueous compositions, including household and industrial products, and especially personal care products, which require a less acidic pH range than in which isothiazolone is stable in the presence of cationic salts.