Seminar:

Profile: Gayan earned his B.S. in Chemistry at the University of Kelaniya, Sri Lanka (2005), and Ph.D. in Chemistry at the University of Iowa with Vicki H. Grassian (2011). After receiving his doctorate degree, he started his career as a Postdoctoral Research Scholar at the University of Iowa. During this time he was also rewarded the opportunity to work as a visiting assistant professor at the Department of Chemistry. Thereafter he was offered Assistant Professor of Chemistry at Saint Cloud State University, MN. In August 2014, he began his independent research career at NMT. Gayan is the recipient of several awards including A. Lynn Anderson Award for Excellence in Graduate Research (2010) and nominated for the Graduate College D.C. Spriestersbach Dissertation Prize (2012). His research group activities include simulated laboratory studies to discover hidden reaction pathways and mechanisms of complex environmental processes, understand molecular level insights of surface chemistry and photochemistry of mineral oxides and engineered nanoparticles, and develop of catalytic systems for wastewater treatments.

Abstract: Atmospheric mineral dust continue to serve as an important component in climate, ecological balance, and human health. In addition to their environmental relevance, mineral dust also serve as inspiration for the understanding of heterogeneous processes, owing to their complex and chemically rich molecular frameworks. While numerous studies have focused on single component Fe bearing minerals such as hematite, goethite or clay minerals, the impact of non-Fe bearing minerals on Fe dissolution is largely remain unknown. Our studies disclose surface reaction mechanisms that governs the atmospheric processing of Fe-containing mineral dust in the presence of a common semi-conductor oxide, titania (TiO2) – “Fe-Ti hypothesis”. This work further reveals vital mechanistic insights on mineralogical controls in dust iron dissolution by molecular oxygen, acid anions, and solar flux to understand global iron mobilization. On the other hand, airborne mineral dust containing heavy metals can impact on human health. However, the surface chemistry of metal-containing-dust dissolution in lung fluids and the role of mineralogy are poorly understood. More recently, we focused on the dissolution of respirable-sized uranium-containing-dust in simulated lung fluids. We observe that the inhalable dust includes uranium minerals that yield the uranyl cation, UO22+, as the primary dissolved species. Further, the extent of uranium dissolution greatly depends on the mineralogy; the types of uranium minerals as well as non-uranium-minerals in the inhaled dust. Thus, our findings emphasize the importance of site-specific toxicological assessments across mining districts with a specific focus on their mineralogical differences. Given that airborne mineral dust are capable of further transformation and interaction with atmospheric gases, our work also highlights the importance of detailed studies on the surface chemistry of these systems.