A new approach to water disinfection: I. N,N-dimethylalkylbenzyl-polystyrene anion exchange resins as contact disinfectants

Abstract

A quaternary ammonium type anion exchange resin with the N,N-dimethyldodecylbenzyl moiety as the functional group was synthesized and tested as a contact water disinfectant. The long chain alkyl groups are attached to a conventional polystyrene matrix with 2% divinylbenzene as a crosslinker which is insoluble and chemically stable. Suspensions containing up to a total of >10⁹ live cells of the gram positiveBacillus subtilis were disinfected by passage through 1 ml beds of the polymer, Resin 12, at flow rates of 10 to 12 ml min⁻¹ before any viable cells could be detected in the effluent. The disinfectant action increased with increasing temperature and was attributed to the intrinsic antimicrobial properties of the N,N-dimethyldodecylbenzyl function. The large disinfectant capacity and instant disinfection on contact may be understood as a consequence of the extremely high surface concentration of the quaternary functions on the resin beads and the strong hydrophobic effect driving the organisms toward the solution-resin interface. Resin 12 can be regenerated although the ethanolic HCL used in our experiments should be replaced by a less harsh regenerant for practical applications. The results obtained with Resin 12 are to be seen as the demonstration of a new approach to water disinfection using insoluble contact antimicrobials as an alternative to chlorination and other methods based on soluble, reactive agents.