Impact of organic reduced sulfur (thiol) on metal speciation: The case of platinum

The presence of metallic contaminants has major consequences for human health and ecosystems. However, there are many so-called emerging contaminants whose chemical behavior is poorly understood, such as platinum (Pt) and palladium (Pd). It is therefore important to assess their environmental behavior to prevent the risks associated with them. Organic matter has a major impact on the fate of metals in the environment. In particular, Pt and Pd may behave in a particular way by complexing with thiol groups (reduced organic sulfur) in organic matter. The specific affinity of a metal for the thiol groups of organic matter (natural and living) modifies its mobility, bioavailability and toxicity within an ecosystem. The aim of this PhD project is therefore to characterize their physico-chemical interactions in order to better characterize their speciation in the environment. To this end, a range of analytical techniques (coupled or uncoupled), appropriate to the colloidal range, will be developed and/or applied (XAS, ICP-MS, A4F, HPLC) to qualitatively and quantitatively identify metal-organic matter interactions. Using modelling tools, these approaches will allow us to build up a database of interactions between organic matter and metals such as platinum and palladium.