Phenol and phenolic compounds are organic pollutants produced by anthropogenic and natural sources which can regularly be found in atmospheric aqueous aerosols and marine environments. As amphiphilic unsaturated molecules, phenol and its derivatives accumulate at the air-water interface where they can be further processed, e.g. in photochemical reactions with atmospheric trace gases, ultimately leading to the formation of highly oxidized secondary organic aerosols (SOAs). These reactions strongly depend on the surface concentration of phenol and its derivatives at the air-water interface, which can vary as a function of, e.g. bulk concentration, pH, and the presence of other solute species.<br/>Here we present an investigation of the chemical equilibrium of phenol at the air-water interface with liquid-jet photoelectron spectroscopy (LJ-PES). Using a lab-based vacuum ultraviolet (VUV) light source the valence electron spectra of phenol solutions were systematically measured to determine the partitioning of phenol to the solution-vapor interface as a function of bulk concentration. In addition, the acid-base equilibrium of phenol and phenolate was studied. This investigation reveals a Langmuirian adsorption behavior and a strong dependence on the pH. These results set the foundation for further PES experiments following the chemical reaction of phenolic compounds with atmospheric trace gases.

Surfactant properties of phenol in aqueous solutions studied by valence photoelectron spectroscopy

ACS Spring Meeting 2021

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