Sulfidized nanoscale zerovalent iron (SNZVI) is a promising material for groundwater remediation. However, the sulfur speciation in the Fe0 matrix and its effects on SNZVI reactivity, especially it ability to defluorinate organic contaminants are unknown. Here, the effect of S content on the crystalline structure, hydrophobicity, S speciation, and electrochemical properties are determined for SNZVI with S/Fe molar ratios ranging from 0.010 to 0.130. These key material properties explain the reactivity and selectivity of SNZVI during reductive dehalogenation, including defluorination of groundwater contaminants. Sulfur incorporation extended the Fe0 BCC lattice parameter and reduced local vacancies in the structure. FeS and FeS2 were the main sulfur species, and their relative amounts changed with the S/Fe ratio in the particles. The sulfur amount and speciation affected the SNZVI hydrophobicity and hence its reactivity. Impacts of sulfur incorporation on hydrophobicity were consistent with the measured water contact angle. While sulfur in the Fe0 matrix lowered the material’s resistance to electron transfer, the concomitant increase in hydrophobicity inhibited the SNZVI reaction with water, giving it a high selectivity for hydrophobic groundwater contaminants. These findings can guide the rational design of robust SNZVI with properties tailored for specific application scenarios.

Sulfidized nanoscale zerovalent iron: Effect of sulfur content and speciation on reactivity, selectivity, and its ability to defluorinate organic groundwater contaminants

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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