Building Complexity in Multiphase Bleach Vapor Chemistry from the Bottom Up
DOUGLAS COLLINS, Lauren Stettler, Christina Clarke, Olivia Jaye, Ryan Ziskin, Bucknell University
Abstract Number: 231
Working Group: Chemicals of Emerging Concern in Indoor and Outdoor Aerosol: Sources, Vectors, Reactivity, and Impacts
Abstract
Partitioning and reactive chemical processes at phase interfaces are critically important for scientific understanding indoor environmental quality, including both gas-to-particle and gas-to-building surface processes. The use of chemical disinfection techniques results in the deliberate or incidental release of reactive chemical species throughout indoor spaces in the gas phase and in deposited films on indoor surfaces. Chlorine bleach, for one, is known to release gaseous molecular chlorine (Cl2) and hypochlorous acid (HOCl) to indoor air along with its surface reactivity upon application. This presentation will describe advancements in our understanding of the chemical consequences of multiphase chemistry involving gaseous HOCl and Cl2 in laboratory studies. Focus will be placed on their reactivity with mixed organic surface films composed of oxygenated aromatic compounds and unsaturated fatty acids. Prior results in the environmental and biochemical literature have clearly demonstrated the broad oxidative reactivity of HOCl and our own results suggest that multiphase bleach vapor reactions may generate products of toxicological concern. However, the significant chemical complexity of real environmental surface films alters reaction pathways idealized by simplified study systems. Our experiments demonstrate unintuitive outcomes that are supported by the invocation of catalytic processes involving reactive oxygen species. For instance, the formation of certain chlorination and oxidation products of oleic acid under bleach vapor exposure can be modulated by the presence of aromatic species that may be forming reactive intermediates that act as redox mediators, all while the identities of reaction products are unchanged. These findings are complementary to existing and emerging research on the importance of condensed-phase reactive intermediates in driving environmental surface chemistry. At the same time, the chlorine in bleach vapor imparts electronic effects to aromatic species that modulate their reactivity and can also confer consequences for human and ecosystem health.