REACTIVITY OF ELEMENTAL SULFUR NANOPARTICLES AND THEIR ROLE ON THE BIOGEOCHEMICAL CYCLING OF SULFUR
HS- + (n-1)/8 S8 = Sn2- + H+ (1)
This reaction can lead to formation of S8 rings via chain elongation reactions of polysulfide (forward direction), or coarsening process of S8-rings to form S8nano and α-S8 (reverse direction). Elemental sulfur is also influenced by the presence of surfactant molecule coatings, similar to microbial organic exudates, that impacts elemental sulfur nanoparticle size and reactivity.
We employ an array of molecular methods in order to investigate S8nano coarsening processes and nucleophilic dissolution (reaction 1), incorporating electrochemical, chromatographic, spectrophotometric and spectroscopic techniques. The experimental data show that the kinetics of the reaction are influenced significantly by the surface area of the nanoparticles, the amount of the electron nucleophile (HS-), as well as the surface character of elemental sulfur (organic surfactant coating).
Observed sulfur speciation in Yellowstone National Park thermal areas indicates nucleophilic dissolution of elemental sulfur (reaction 1), is a key control on the (bio)availability of sulfur species in solution, and is an important link to the carbon cycle in these systems via sulfurization of organic matter.