Carnegie Mellon University
Rachel Molé is a Ph.D. student in Civil and Environmental Engineering at Carnegie Mellon University. She earned her B.A. in Chemistry from The College of Wooster in 2017 and earned her M.S. in Civil & Environmental Engineering at Carnegie Mellon in 2020. She has research experience with environmental analytical chemistry, toxicology, and engineering. Her doctoral work is advised by Dr. Gregory Lowry and is sponsored by the Department of Defense SERDP. Her research is focused on understanding how geochemical factors influence the performance of in situ colloidal activated carbon barriers for preventing the migration of perfluoroalkyl substances (PFAS) in groundwater.
Ionic strength and natural organic matter affect adsorption of perfluoroalkyl substances to colloidal activated carbon and its performance as an in-situ barrier for groundwater remediation
Subsurface injection of colloidal activated carbon (CAC) is an emerging in situ remedial technology for the treatment of perfluoroalkyl substances (PFAS) in groundwater. CAC barriers reduce mass flux and slow plume migration, thereby lowering the risk of exposure. However, there is uncertainty surrounding long-term barrier performance, particularly for short-chain PFAS and when influenced by changing geochemical conditions. To address these questions, here we performed batch adsorption isotherms with a CAC under various water chemistry conditions. Isotherm results were paired with CAC characterization to understand the mechanism of adsorption to CAC as a function of PFAS structure. Isotherm results were then used in a groundwater model to quantify the impact of changing water chemistry on in situ barrier longevity. This work addresses key questions surrounding the implementation in situ CAC barriers for PFAS remediation and will help inform decisions regarding their use at contaminated sites