Photocatalytic Reaction of Gas-Phase Naphthalene on Paint- and Sunscreen-Coated Surfaces

Abstract EN

The uses of metal oxide nanoparticles in modern paint and sunscreen formulations are widespread.

Through materials characterization and kinetic experiments, it is demonstrated that fresh surface coatings of paint and sunscreen photocatalytically degrade gaseous naphthalene.

The primary metal oxides are TiO2 in the form of the rutile phase in paint and as anatase in sunscreen formulations.

Other metal oxides present are Al2O3 and ZnO.

Several organic fillers that are photochemically active are also present in paint and sunscreen samples but are unidentified.

Reaction rate constants increased with increasing air relative humidity, due to the production of surface hydroxyl radical, and decreased with increasing coating thickness, due to mass transfer limitations.

Photocatalytic degradation on these freshly generated surfaces is observed to be fast, with naphthalene half-lives shorter than 30 minutes.

This work demonstrates that large, semivolatile organic compounds can react photochemically on freshly generated paint- and sunscreen-coated surfaces and may impact air quality in both indoor and outdoor environments.