Combinations of the broad spectrum, demand-type quaternary ammonium resin-polyiodide bactericide and virucide were prepared in the triiodide, pentaiodide, and heptaiodide forms by fluidized bed method in a closed aqueous system at elevated temperatures. The resin-triiodide combination is now in use as a disinfectant for water. The triiodide disinfectant prepared by this method is equal to the product obtained by a room temperature batch contact process and can be prepared in a considerably shorter time. Analyses of the supernatant solutions revealed increasingly higher iodine concentrations with higher polyiodide species in the resin combination. A long run elution study of one resin-pentaiodide combination is reported. All combinations, from triiodide to heptaiodide, were in the form of black, shiny beads, with increasing contraction of the beads observed with increasing iodine content. A significant fraction of the resin-heptaiodide beads were fractured due to internal stresses which caused the contraction.

Outlines the mechanism for the simple iodine clock reaction and the "Old Nassau" modification.

The resin-I5 column developed in our laboratories rendered aqueous suspensions containing up to 5 X 10(4) cysts of Giardia muris or Giardia lamblia per ml incapable of excystation. The inhibition of excystation was effective at both 4 and 25 degrees C. The addition of Na2S2O3 to column eluates containing cysts appeared to partially reverse the disinfectant action, and the reversal was more pronounced at 4 degrees C than at 25 degrees C. In contrast, the rapid removal of cysts from the column eluates by centrifugation and filtration or the use of other reductants, notably cysteine and glutathione, did not similarly reverse the disinfectant properties of the column. Based on these data, we suggest that the disinfecting agent is acquired by the cyst in its passage through the resin column and that either the disinfecting agent or its reaction can be partially and specifically neutralized by Na2S2O3. We hypothesize that the time between disinfectant acquisition and activity is a function of the thickness of the Giardia cyst wall and consequently takes longer at the lower temperature. Nevertheless, resin-I5 appears to inactivate a larger number of cysts in a shorter period of time with lower residual halogen levels than do agents of other published methods.

Many school colors can be generated using the directions for acid-base demonstrations in this article.

No abstract