Photocatalytic removal of gaseous ethanol, acetaldehyde and acetic acid: from a fundamental approach to real cases

ABSTRACT

The photocatalytic oxidation of volatile organic compounds (VOCs) has been extensively investigated. With respect to water treatment, photocatalytic degradation of air pollutants is still less understood, but this has not prevented photocatalytic building materials and air purifiers to reach the market. Here, we provide a selective overview of the current understanding on VOC photocatalytic oxidation, focusing on ethanol, acetaldehyde, and acetic acid. Among the main indoor pollutants, these molecules are also oxidation intermediates of numerous VOCs. Their adsorption at the photocatalyst surface is first presented, based on theoretical and experimental evidence. Reaction intermediates are discussed, comparing proposed reaction mechanisms. The role of the photocatalyst features in directing adsorption and oxidation phenomena is highlighted, encompassing both TiO₂ and emerging photocatalysts. We then critically discuss gaps in our knowledge, such as the effect of air humidity, multi-pollutant interactions and deactivation pathways. Finally, attempts to model VOC degradation in realistic conditions are reviewed.

KEYWORDS:

• Pollutant remediation
• titanium dioxide
• air purifiers
• air quality
• household pollution
• reaction pathway
• photocatalytic oxidation
• deactivation pathways

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Eleonora Pargoletti

Dr. Eleonora Pargoletti got her Bachelor's in Chemistry and Master's degree in Chemical Science (both cum laude) at University of Milan in 2013 and 2015, respectively. She received her PhD in Industrial Chemistry at University of Milan in January 2020 discussing a Thesis about the engineering of 3D nanonetworks to be applied as gas sensors and optoelectronic materials. During the PhD period, she won an Erasmus Mundus scholarship thanks to which she spent six months as visiting student at the Nanotechnology Research Laboratory of Prof. Tricoli (Australian National University). Now, she is a Post-Doc Fellow focusing on nanoarchitectonics of functional materials for both (photo-)sensing and energy applications.

Luca Rimoldi

Dr. Luca Rimoldi got his Master's Degree in Chemical Sciences (magna cum laude) at the University of Milan in 2015. In 2017, he joined the group of Prof. Raffaella Buonsanti at École Polytechnique Fédérale de Lausanne (EPFL) as a visiting student. He received his PhD in Chemistry in 2019 at the University of Milan, defending a thesis on innovative oxide materials for photocatalytic, energy and smart surfaces applications. His main interest is the study of nanostructured photocatalysts for the removal of emerging (micro)pollutants and of volatile organic compounds.

Daniela Meroni

Dr. Daniela Meroni, Department of Chemistry, Università degli Studi di Milano, via Golgi 19, 20133, Milano.

Giuseppe Cappelletti

Prof. Giuseppe Cappelletti, Department of Chemistry, Università degli Studi di Milano, via Golgi 19, 20133, Milan, Italy.