Hydantoin-enhanced halogen efficacy in pulp and paper applications
AssigneeLonza Ltd.
InventorPhilip G. Sweeny
Life of this patent
Estimating the term…
Abstract
Free halogen sources (e.g., sodium hypochlorite and chlorine) added as slimicides in high organic component process streams such as pulp and paper processing are rendered more efficacious by the addition of selected N-hydrogen compounds (namely, 5,5-dimethylhydantoin, 5-ethyl-5-methylhydantoin, cyanuric acid, succinimide, urea, 4,4-dimethyl-2-oxazolidinone, and glycouril) to the process stream. The latter compounds may be added to the process stream before or after the slimicide is added or combined with the slimicide and added directly thereto. The direct use of halogenated hydantoins has also been found to provide improved efficacy relative to free halogen sources. In addition, absorbable organic halogen by-products are reduced.
Claims13
A method of enhancing the efficacy of a free halogen-generating slimicide and reducing organic halogen by-products in an organic matter-containing circulating water system which comprises adding an N-hydrogen compound selected from the group consisting of p-toluene-sulfonamide, dimethylhydantoin, methylethylhydantoin, cyanuric acid, succinimide, urea, 4,4-dimethyl-2-oxazolidinone, and glycouril, directly to said system before or after the addition of the slimicide or with said slimicide in a mixture consisting essentially of the slimicide and said compound;
- wherein the N-hydrogen compound is added at a ratio sufficient to maintain a 0.1:1 to 10:1 mole ratio of slimicide to N-hydrogen compound in the circulating system, wherein at least 0.2 weight percent of said organic matter is present in said system, wherein the slimicide is chlorine gas, bromine, bromine chloride, an alkali metal or alkaline earth metal hypohalite, a halogenated hydantoin, a halogenated cyanurate, or halogenated cyanuric acid, and wherein said mixture of the N-hydrogen compound and the slimicide is present in said system in a slimicidally effective amount.
A method of enhancing the efficacy of a free halogen-generating slimicide and reducing organic halogen by-products in an organic matter-containing circulating water system which comprises adding an N-hydrogen compound selected from the group consisting of p-toluene-sulfonamide dimethylhydantoin, methylethylhydantoin, cyanuric acid, succinimide, urea, 4,4-dimethyl-2-oxazolidinone, and glycouril, directly to said system before or after the addition of the slimicide or with said slimicide in a mixture consisting essentially of the slimicide and said compound;
- wherein the N-hydrogen compound is added at a ratio sufficient to maintain a 0.1:1 to 10:1 mole ratio of slimicide to N-hydrogen compound in the circulating system;
- and wherein at least 0.2 weight percent of said organic matter is present in said system, wherein said slimicide is a halogenated hydantoin of the formula:
- ##STR3## wherein R.sub.1 and R.sub.2 are independently selected from the group consisting of lower alkyl having 1 to 12 carbon atoms, wherein X.sub.1 and X.sub.2 are independently selected from the group consisting of bromine and chlorine, and wherein the mixture of the N-hydrogen compound and the slimicide is present in said system in a slimicidally effective amount.
Dependencies are inferred from the claim text.