Methods and articles for maintaining hydantoinylated polymers in a biocidally active state

Abstract

A composition and the method for sustaining the biocidal activity of chlorinated polystyrene hydantoin beads. The method comprises supplying a continuous low level halogen concentration to the chlorinated polystyrene hydantoin beads in the water to be treated that flows in contact with the chlorinated polystyrene hydantoin beads, resulting in treated water suitable for drinking.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of Provisional Patent Application No. 60 / 507,735, filed Oct. 1, 2003, incorporated herein by reference.FIELD OF THE INVENTION [0002] The invention is related to water purification systems, including systems employing polymers having pendant heterocyclic amine groups, such as polystyrene having pendant hydantoin and halogenated hydantoin groups, and to the compositions and methods for maintaining the polymers in a biocidally active state. BACKGROUND OF THE INVENTION [0003] Heterocyclic N-halamine groups are known to have biocidal properties that can be put to use in water purification. Heterocyclic N-halamine groups that are attached to a polystyrene polymer are described in U.S. Pat. No. 5,490,983. A crosslinked polystyrene polymer having similar pendant heterocyclic N-halamine groups is described in U.S. Pat. No. 6,548,054. The crosslinked version of the polystyrene polymer is typically provided in be...

AI Technical Summary

Benefits of technology

[0008] In accordance with the present invention, the need for replacing the halogen-depleted charge of HPSH polymer with new HPSH polymer or taking a water treatment system off-line for recharging, is avoided by providing a low concentration of halogen in the water that is to be treated that is sufficient to maintain the HPSH polymer at an effective biocidally active state. Ideally, the concentration is sufficient to maintain the HPSH polymer biocidal, yet not so high as to render the treated water undrinkable due to high concentrations of halogen. In this manner, the HPSH polymer is constantly maintained at an effective biocidal level, thus eliminating replacement or recharging. However, one of the difficulties of implementing this new solution is in achieving a prolonged low concentration of free halogen in water to bond with the heterocyclic amines to render them biocidal, yet not have the halogen concentration so high as to adversely effect water potability.

[0010] In accordance with the present invention of prolonging the biocidally active state of polymers having pendant heterocyclic amine groups, the present invention provides methods and the means to maintain continuously or for a prolonged period of time a low concentration of free halogen in water to maintain or prolong the effective halogen loading on polymers having pendant heterocyclic amines. The present invention avoids the need to recharge the polymers after they have become biocidally ineffective and also avoids the need to take a water purification system off-line for recharging biocidally ineffective polymers. With the use of the present invention, the polymers having pendant heterocyclic amine groups are maintained biocidally effective constantly or for at least prolonged periods of time. The present invention treats the polymers having pendant heterocyclic amine groups with low concentrations of free halogen in water while the polymer is still biocidally effective. Free halogen refers to the halogen in water that is available to bond with a nitrogen atom on a heterocyclic amine. The present invention provides halogens to bond with nitrogen atoms on the heterocyclic amine groups, simultaneously while halogens are being depleted from the heterocyclic amine groups by the biodemand, so that the polymer with pendant heterocyclic amines is not rendered biocidally ineffective. Thus, the need to recharge the polymer from a biocidally ineffective state is avoided. It is to be appreciated that the heterocyclic amine groups may have halogen depleted sites.

[0012] In one embodiment, the article of the invention is a solid, monolithic tablet that elutes chlorine or bromine within predetermined limits into untreated flowing water that is subsequently exposed to a biocidally active polymer having pendant heterocyclic N-halamine groups. The method and article according to the invention achieve the constant or prolonged biocidally active state of polymers having pendant heterocyclic N-halamines by replacing the halogens that are constantly being depleted by the biodemand. This is in direct contrast to Worley et al. '983 and '054 that only recharges the polymer after the polymer has been depleted of halogen that has rendered the polymer biocidally ineffective. With the article according to the invention, the biocidally active state of any polymer having pendant heterocyclic N-halamine groups can be maintained continuously or at the very least for a prolonged period of time as compared with the prior art that only recharges the polymer after the polymer has been rendered biocidally inactive.

Problems solved by technology

Ideally, the concentration is sufficient to maintain the HPSH polymer biocidal, yet not so high as to render the treated water undrinkable due to high concentrations of halogen.

However, one of the difficulties of implementing this new solution is in achieving a prolonged low concentration of free halogen in water to bond with the heterocyclic amines to render them biocidal, yet not have the halogen concentration so high as to adversely effect water potability.

However, these commercially available sources of halogens elute free halogens at concentrations far greater than would be accepted by consumers for drinking water.

Furthermore, no mention of a means for continuously maintaining or least prolonging the biocidally active state of HPSH polymer is described.

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