Contamination

Chemistry

Ecology

Trichloroethylene

Reductive dechlorination

Telecommunications

Biodegradation

Permeable reactive barrier

Organic chemistry

Reactivity (psychology)

Biology

Catalysis

Degradation (telecommunications)

Environmental remediation

Environmental chemistry

Borohydride

Computer science

Adsorption

Pathology

Inorganic chemistry

Acetylene

Groundwater remediation

Zerovalent iron

Alternative medicine

Medicine

Environmental Science & Technology

Sulfidated nanoscale zerovalent iron (S-nZVI) has the potential to be a cost-effective remediation agent for a wide range of environmental pollutants, including chlorinated solvents. Various synthesis approaches have yielded S-nZVI consisting of a Fe0 (or Fe0/S0) core and FeS shell, which are significantly more reactive to trichloroethene (TCE) than nZVI. However, their reactivity is not as high as palladium-doped nZVI (Pd-nZVI). We synthesized S-nZVI by the co-precipitation of FeS and Fe0 by using Na2S during the borohydride reduction of FeSO4 (S-nZVIco). This resulted in FeS structures bridging the nZVI core and the surface, as confirmed by electron microscopy and X-ray analyses. The TCE degradation capacity of up to 0.46 mol TCE/mol Fe0 was obtained for S-nZVIco at a high S loading and was comparable to Pd-nZVI but 60% higher than the currently most reactive S-nZVI, in which FeS only coats the nZVI (S-nZVIpost). The high TCE degradation was due to complete utilization of Fe0 (2 e–/mol Fe0) toward the formation of acetylene. Although Pd-nZVI yielded 3 e–/mol Fe0, TCE degradation was comparable because it reduced acetylene further to ethene and ethane. Under Fe0-limited conditions, the S-nZVIco TCE degradation rate was 16 times higher than that of Pd-nZVI (0.5 wt % Pd) and 90 times higher than that of S-nZVIpost.

Optimal Design of Sulfidated Nanoscale Zerovalent Iron for Enhanced Trichloroethene Degradation