The environmental fate of contaminants of emerging concern (CECs), such as pharmaceuticals, is influenced by the extent of their sorption onto soils and sediments. A large number of CECs contain functional groups (COOH and OH) that are potentially anionic at environmentally relevant pH values (3.5-8) and can sorb onto the surface of soil—through cation bridging and surface complexation. While there is an established predictive model for the sorption of non-polar and polar-neutral compounds, comparable models have not been developed for anionic CECs that sorb via the above mentioned distinct mechanisms. This research i) evaluated the potential for using hydratropic acid (HA) and salicylic acid (SA) as small and simple probe compounds that capture soil receptor site densities and baseline driving forces for sorption via cation bridging and surface complexation and ii) validated the use of probe compounds via comparison with larger and more complex anionic CECs. To this end, we determined the sorption coefficient (K<sub>d</sub>) of two probe compounds (e.g., HA and SA) and a range of anionic CECs (e.g., Sulfasalazine and Ibuprofen) to 30 well-characterized soils and select pure phase minerals. Preliminary results indicated that 1) SA was an effective probe for compounds that sorb primarily via surface complexation (e.g., Sulfasalazine) and 2) HA was a good probe for compounds that sorb primarily via cation bridging (e.g., Ibuprofen) and 3) both probes were better predictors for sorption than traditional soil properties (e.g., surface area, % organic matter and dithionite-citrate-bicarbonate extractable Al and Fe).

Predicting sorption of anionic pharmaceuticals to soils: An evaluation of potential probe compounds

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.