Date of Award
Master of Science (MS)
Aerosols, Aqueous-Organic, Atmosphere, PAH, Photolysis, Sodium Chloride
Physical Sciences and Mathematics
Polycyclic aromatic hydrocarbons (PAHs) are dangerous pollutants. The photolysis kinetics of PAHs are of interest because they are carcinogenic and can increase in toxicity through photodegradation into secondary products. They are often associated with particulate matter. The composition and physical properties of the particulate matter can affect PAH photolysis kinetics. We investigated the effects of sodium chloride on the photolysis kinetics of the PAH anthracene in water and octanol as well as mixed-phase solutions (water-octanol), which were used as models for aqueous-organic aerosols. A non-linear dependence on sodium chloride concentrations was observed. Sodium chloride enhanced photolysis at concentrations up to 0.25 M due to increased singlet oxygen (1O2) production, and suppressed photolysis at higher concentrations because of anthracene quenching. A positive dependence on sodium chloride concentration above sodium chloride’s saturation limit in aqueous solution (6.1 M) suggested that new reaction pathways, potentially on the surface of solid sodium chloride, may be occurring. 0.25 M sodium chloride increased rate constants in octanol and aqueous-organic mixtures, but to a lesser extent than in water. An increase of a factor of 9 was observed when 0.25 M sodium chloride was included in aqueous solutions, while the increase in octanol was a factor of 2. Stirring aqueous-organic mixtures during photolysis increased photolysis rates in the absence of salt, but had inconsistent effects in the presence of 0.25 M sodium chloride.
Blaha, Kyle, "Effects of Sodium Chloride on Anthracene Photolysis Kinetics in Aqueous-Organic Solutions" (2017). Theses - ALL. 178.