Impact of pH and NaCl and CaCl2 Salts on the Speciation and Photochemistry of Pyruvic Acid in the Aqueous Phase
- 22 May 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 124 (25), 5071-5080
- https://doi.org/10.1021/acs.jpca.0c01016
Abstract
Recent studies have shown that pyruvic acid can produce higher-molecular-weight compounds upon irradiation in the aqueous phase. These compounds can contribute to the formation of secondary organic aerosols. There have been several previous studies on the effect of ionic strength on the photochemistry of pyruvic acid, however; few of them investigated the effects of marine relevant salts such as NaCl and CaCl2. In this study, we examine the effect of NaCl and CaCl2, namely the containing coordinating cations Na+ and Ca2+, on the speciation, absorption properties and photoreactivity of pyruvic acid in aqueous solutions of varying pH. NMR shows that both Ca2+ and Na+ further deprotonate pyruvic acid and decrease the diol to ketone ratio of pyruvic acid than in pure water at the same pH, especially at more acidic pH (pH less than 4). The absorption spectrum shows a strong red shift in the peak maxima for the n → π* transition of pyruvic acid in NaCl/CaCl2 solutions. This dependence is much more pronounced for divalent cations (Ca2+) compared to monovalent cations (Na+). Vertical excitation energy calculations of the anionic ketone form of pyruvic acid confirm the same red shift on the n → π* transition peak in the presence of Ca2+. In addition, the presence of NaCl/CaCl2 suppress the photolysis rate of pyruvic acid, which could be due to the deprotonation of pyruvic acid by the cations and the lower photochemical reactivity for pyruvate, the deprotonated form.Keywords
Funding Information
- National Science Foundation (1801971)
This publication has 90 references indexed in Scilit:
- Phase partitioning of soluble trace gases with size‐resolved aerosols in near‐surface continental air over northern Colorado, USA, during winterJournal of Geophysical Research: Atmospheres, 2013
- Size-Dependent Changes in Sea Spray Aerosol Composition and Properties with Different Seawater ConditionsEnvironmental Science & Technology, 2013
- Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosolProceedings of the National Academy of Sciences of the United States of America, 2013
- Light induced multiphase chemistry of gas-phase ozone on aqueous pyruvic and oxalic acidsPhysical Chemistry Chemical Physics, 2009
- Secondary organic aerosol yields from cloud‐processing of isoprene oxidation productsGeophysical Research Letters, 2008
- Cooperative Hydration of Pyruvic Acid in IceJournal of the American Chemical Society, 2006
- Link between isoprene and secondary organic aerosol (SOA): Pyruvic acid oxidation yields low volatility organic acids in cloudsGeophysical Research Letters, 2006
- Photoinduced Oligomerization of Aqueous Pyruvic AcidThe Journal of Physical Chemistry A, 2006
- The Photochemistry of α-Keto Acids and α-Keto Esters. I. Photolysis of Pyruvic Acid and Benzoylformic AcidJournal of the American Chemical Society, 1963
- Complex Formation between Carboxylic Acids and Divalent Metal CationsJournal of the American Chemical Society, 1938