AGEP-T FRAME Fellow: Benedette Adewale
Graduate Student, Stony Brook University
Department of Chemistry
AGEP-T FRAME Research Mentor: Dr. Dale Drueckhammer
Benedette Adewale was raised in Lagos, a city in Nigeria and at the age of 17 years old, her family moved to Staten Island, NY. She found her passion for science in high school and this enabled her to choose chemistry as a major. She developed a strong passion for research through the Louis Stokes Alliances for Minority Participation (LSAMP) program as an undergraduate student and subsequently the Bridges to Doctorate (BD) program as a graduate student in City College.
She holds an MS in Chemistry from City College of New York and a BS in Chemistry from CUNY, College of Staten Island. In 2014 she was awarded the W. Burghardt Turner Dissertation Fellowship. In her spare time, she enjoys singing, community service, reading and different outdoor activities.
Seminar Title: Sorption of dioctyl sodium sulfosuccinate to Coastal Gulf of Mexico Sediment
Description: Dioctyl sodium sulfosuccinate (DOSS) is a major ingredient in Corexit 9527 and 9500 dispersants used to mitigate some effects of the Deep-water Horizon oil spill. DOSS proved to be relatively persistent in seawater and was detected in water column and sediment samples. Sorption to suspended particles affects the distribution and fate of similarly hydrophobic anionic surfactants in saline nearshore environment. Better understanding of DOSS sorption is also important for predicting fate in nearshore environments, and can constrain interpretations or hypotheses related to the use of DOSS as a water mass tracer or the mechanisms responsible for levels of DOSS detected in some sedimentary regimes, (up to (2-9 µg/g) at one site). The sorption of DOSS to coastal marine sediments was determined to characterize the effects on sorption of solution properties, DOSS concentration (1- 17,000 µg/L), and sediment properties in order to improve predictive capabilities for DOSS speciation across a range of water compositions. Sorption onto 12 sediments with varying combinations of properties (e.g., organic carbon contents of 0.18 – 8.59 %) resulted in isotherms that were most often nearly linear at more environmentally relevant concentrations (1-200 µg/L). Total organic carbon content was also a surprisingly good predictor of sorption with carbon normalized sorption coefficients averaging 7500 ± 2500 L/Kg. These results suggest and even more important role of organic matter than determined for better studied anionic surfactants, linear alkylbenzene sulfonates (LAS), potentially related to well document unique properties of DOSS at H2O/oil interfaces. In regards to effects of solution properties, the dependence on pH was much less than described in prior studies of anionic surfactant sorption under low ionic strength conditions, and the increased sorption with salinity could be described empirically by a linear combination of the independently determined effects of Ca2+, Mg2+, and Na+. While the importance of Ca2+ on sorption of organo-sulfonates is well recognized, the increasing importance of Na+ with salinity at low surfactant concentrations presents questions about the mechanisms involved. The very important effects of Mg2+ (neglected in prior sorption studies with organic compounds) is a novel result, with implications for marine and freshwater systems, where the Mg2+/Ca2+ is highly variable. The results obtained will be compared to mechanistic sorption models.
Dasgupta, S., Adewale, BS., Brownawell, BJ., McElroy, A. Acute toxicity and genotoxicity of dispersants Corexit 9500 and 9527 and their components on early life stages of sheepshead minnow (Cyprinodon variegatus). In prep.