Data Files Accompanying: Zinc–Carboxylate Binding in Mixed Octadecanoic Acid and Octadecanol Monolayers on 
Proxy Seawater Solution Surfaces

Authors: Nicole C. Auvil†, Maria G. Vazquez de Vasquez†, and Heather C. Allen*
Journal: ACS Earth and Space Chemistry

Contact: 
Heather C. Allen, allen@chemistry.ohio-state.edu, Department of Chemistry & Biochemistry, The Ohio State University

Cite as:
Auvil, N. C.; Vazquez de Vasquez, M. G.; Allen, H. 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.
DOI: 10.6075/J01836NN

Abbreviations:
Isotherm: Surface pressure-area isotherm (Π-A)
IRRAS: Infrared reflection absorption spectroscopy
FTIR: Fourier transform infrared 
MCT: HgCdTe
MMA: Mean Molecular Area
RA: Reflectance-absorbance
R: Reflectivity of a monolayer
R0: Reflectivity of a monolayer free aqueous surface
Octadecanoic acid: OA, stearic acid, C18OOH 
Octadecanol: OL, stearyl alcohol, C18OH
Sea Surface Microlayer: SSML
A and Amax are peak intensity and maximum peak intensity 
Ka: affinity constant 
n: empirical constant
Kb[S]: binding parameter of Step 2[S]: density of surface binding sites

Files:
85_15 SA_OD ratio
90_10 SA_OD ratio
95_5 SA_OD ratio
100_0 SA_OD ratio

Filenames represent ratios of fatty acid to fatty alcohol, where SA is stearic acid and OD is stearyl alcohol. For example, "85_15 SA_OD ratio" means 85% stearic acid and 15% stearyl alcohol.

Folders:
IRRAS_data

Experimental Methods for Data Collection:
Materials
The materials used in this study were purchased commercially and used without further purification unless otherwise noted. Octadecanoic acid (OA, stearic acid, a C18 fatty acid, Sigma-Aldrich, ≥ 98.5% grade 1) and octadecanol (OL, stearyl alcohol, a C18 fatty alcohol, 99%, Sigma-Aldrich) were dissolved in chloroform (HPLC Grade, Fisher Scientific) to make ~3.8 mM OA and OL stock solutions. These solutions were combined in varying proportions to prepare ~3.8 mM mixed solutions at the ratios 100:0, 95:5, 90:10, and 85:15 OA:OL (w/w). Sodium chloride salt (NaCl) (99.999% trace metals basis, Aldrich, and 99.998% trace metals basis, Fisher Scientific) was baked in a furnace at 675°C for >8 hours to remove possible organic contamination. 
Zinc chloride salt (ZnCl2) (99.999% trace metals basis, Aldrich) was used as purchased. NaCl and ZnCl2 salt solutions were prepared using ultrapure water with a resistivity of 18.2 MΩ•cm (Milli-Q® Advantage A10, MilliporeSigma, Burlington, MA). The NaCl solution was filtered through Dionex OnGuard II M cartridges (Thermo Fisher Scientific) to remove possible trace metal impurities. NaCl and ZnCl2 solutions are combined in the Langmuir trough to create the solution. The measured pH of the mixed salt solutions was 5.7 ± 0.15
Surface Pressure-Area Isotherms
	Teflon Langmuir trough; Biolin Scientific Paramus, NJ
	Delrin barriers
	Wilhelmy plate method: using precut filter paper plates (Ashless grade, Whatman)
	Each isotherm was averaegd in Origin 9.0.0
	Error shown is 1 standard deviation from the mean and was calculated in Origin 9.0.0
Infrared Reflection Absorption Spectroscopy
	FTIR spectrometer (Frontier, Perkin Elmer, United States) with liquid nitrogen cooled HgCdTe (MCT) detector
	Each IRRAS spectrum was averaegd in Origin 9.0.0
	Error shown is 1 standard deviation from the mean and was calculated in Origin 9.0.0