[Show abstract][Hide abstract] ABSTRACT: The David L. Tippin Water Treatment Facility in Tampa, Fla., treats Hillsborough River water, which has relatively high organic matter content, especially during high-rainfall seasons. In 2001, ozonation and biologically activated carbon (BAC) filtration were implemented along with a few additional modifications to the existing conventional process. After the start of the new process, unexpectedly low monochloramine formation efficiency and rapid decay of monochloramine residual in treated waters were observed. By changing the sequence of free chlorine and ammonia injection and by providing sufficient mixing and reaction time for free chlorine, monochloramine formation efficiency was dramatically increased. Among several factors that might affect monochloramine decay rate, the particulate matter produced from the BAC filters, presumably because of microbial activities, was found to be primarily responsible for the monochloramine demand. The filter backwashing practice was modified to successfully enhance filter performance and stabilize monochloramine in treated waters.
[Show abstract][Hide abstract] ABSTRACT: While the reactivity of C60 has been described in a variety of organic solvents, little information is available regarding aqueous-based reactions due to solubility limitations. In this study, a reaction between C60, as a nanoscale suspension, and dissolved ozone in the aqueous phase was investigated. Findings indicate a facile reaction occurs, resulting in aggregate dissolution concurrent with formation of water-soluble fullerene oxide species. Product analyses, including 13C NMR, MS (LDI), FTIR, UV-Vis, and XPS, indicate highly oxidized fullerene with an average of approximately 29 oxygen additions per molecule, arranged in repeating hydroxyl and hemiketal functionalities. These findings are significant in that they (1) demonstrate the feasibility of other aqueous-based fullerene chemistries, including those for alternative synthesis routes, which might otherwise be considered prohibitive on the basis of solubility limitations, and (2) imply that the aqueous reactivity of fullerene-based materials must be considered appropriately for accurate assessment of their transport, fate, and potential risk(s) in environmental systems.