Selective photoreduction of acetonitrile to acetaldehyde in dilute aqueous solutions

Abstract

Acetonitrile is a commonly used solvent in both industry and research. The treatment of acetonitrile wastes in dilute aqueous solutions with visible light offers advantages to chemical treatment and ultraviolet (UV) irradiation. This study presents the degradation of acetonitrile via a photoinduced electron transfer reaction in the presence of a photosensitizer (dye) and a sacrificial reductant under visible light. Acetonitrile photodegradation (photoreduction) was investigated utilizing a variety of sacrificial reductants and photosensitizers. Optimal results were observed in the presence of methylene green and tri-isopropanolamine with a decrease of acetonitrile in solution to 86% in 24 hours. The only photoreaction product observed was acetaldehyde and a plausible mechanism for the photochemical degradation of acetonitrile is proposed.

Keywords:

• acetonitrile
• dye
• irradiation
• light
• photodegradation
• treatment
• waste

Acknowledgments

This research project would not have been possible without the invaluable support and guidance of the late Professor Gary Epling. He was a 1967 graduate of MIT and received his PhD degree from the University of Wisconsin (Zimmerman 1972). His post-doctoral work was done at Yale in 1973. He was a professor at Fordham University from 1973 to 1978, when he came to the Chemistry Department at the University of Connecticut and served as the Head. Professor Epling has published over 70 scholarly articles.