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Publication abstract: Organic coatings on sea spray aerosol are largely comprised of fatty acids in addition to a vast array of other organic molecules including fatty alcohols. The seawater from which sea spray aerosol originates contains metal ions that interact with the organic coating at the air-seawater interface, resulting in transport of these metals into the atmosphere. Metal binding within single-substance monolayers on aqueous solutions has been previously studied. However, such binding events within mixed monolayers, especially those of ocean relevant ratios, are not well explored. Here we examine four monolayer ratios of octadecanoic acid (stearic acid) to octadecanol (stearyl alcohol) on aqueous solutions with varying ZnCl2 concentrations and a seawater-relevant NaCl concentration of 0.465 M. Surface pressure–area (Π-A) isotherms and infrared reflection-absorption spectroscopy (IRRAS) are used to quantify the Zn2+–carboxylate surface binding affinities for each monolayer composition. We find that: Zn2+–carboxylate binding is enhanced by ~300 times at the surface when compared to the bulk solution. Addition of 10% octadecanol reduces the apparent surface binding affinity by over 50% from 3.6 × 103 to 1.4 × 103 M-1; this is significantly more than predicted from the slight reduction in viable 1:1 binding sites. Furthermore, 1:2 Zn2+–carboxylate binding is shown to only be viable for the 100% and 95% fatty acid film whereas 1:1 binding is observed for all film ratios investigated. Research Data Curation Program, UC San Diego, La Jolla, 92093-0175 (https://lib.ucsd.edu/rdcp) Auvil, Nicole C.; Vazquez de Vasquez, Maria G.; Allen, Heather C. (2021). Data from: Zinc–Carboxylate Binding in Mixed Octadecanoic Acid and Octadecanol Monolayers on Proxy Seawater Solution Surfaces. In Center for Aerosol Impacts on Chemistry of the Environment (CAICE). UC San Diego Library Digital Collections. https://doi.org/10.6075/J01836NN
Binding constant Stearyl alcohol Infrared reflection-absorption spectroscopy (IRRAS) Surface spectroscopy Metal ion enrichment Stearic acid Mixed monolayer Air-water interface Trace metal