Factors Affecting Chlorinated Product Formation from Sodium Hypochlorite Bleach and Limonene Reactions in the Gas Phase

Abstract

During use of sodium hypochlorite bleach, gas-phase hypochlorous acid (HOCl) and chlorine (Cl₂) are released, which can react with organic compounds present in indoor air. Reactivity between HOCl/Cl₂ and limonene, a common constituent of indoor air, has been observed. The purpose of this study was to characterize the chemical species generated from gas-phase reactions between HOCl/Cl₂ and limonene. Gas-phase reactions were prepared in Teflon chambers housing HOCl, Cl₂, and limonene. The resulting chemical products were analyzed using gas-phase preconcentration, followed by gas chromatography and high-resolution mass spectrometry. Several chlorinated products were detected, including limonene species containing one, two, and three chlorines and limonene chlorohydrin. Product concentrations and yields were estimated for the most abundant products, and greater than 80% of transformed limonene was represented in the detected products. Temporal sampling of the reactions allowed time courses to be plotted for limonene decay and chlorinated limonene product generation under different conditions, including the treatments of HOCl/Cl₂, Cl₂ only, high vs low relative humidity, and ± ozone. These experiments add product speciation, yield estimates, and an understanding of environmental factors affecting product formation to previous studies, further highlighting the chemical transformations initiated by sodium hypochlorite bleach in indoor air.