Remediating 1,4-dioxane-contaminated water with slow-release persulfate and zerovalent iron

Ann Kambhu, Megan Gren, Wei Tang, Steve Comfort, Clifford E. Harris

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

1,4-dioxane is an emerging contaminant that was used as a corrosion inhibitor with chlorinated solvents. Metal-activated persulfate can degrade dioxane but reaction kinetics have typically been characterized by a rapid decrease during the first 30 min followed by either a slower decrease or no further change (i.e., plateau). Our objective was to identify the factors responsible for this plateau and then determine if slow-release formulations of sodium persulfate and Fe0could provide a more sustainable degradation treatment. We accomplished this by conducting batch experiments where Fe0-activated persulfate was used to treat dioxane. Treatment variables included the timing at which the dioxane was added to the Fe0-persulfate reaction (T = 0 and 30 min) and including various products of the Fe0-persulfate reaction at T = 0 min (Fe2+, Fe3+, and SO42−). Results showed that when dioxane was spiked into the reaction at 30 min, no degradation occurred; this is in stark contrast to the 60% decrease observed when added at T = 0 min. Adding Fe2+at the onset (T = 0 min) also severely halted the reaction and caused a plateau. This indicates that excess ferrous iron produced from the Fe0-persulfate reaction scavenges sulfate radicals and prevents further dioxane degradation. By limiting the release of Fe0in a slow-release wax formulation, degradation plateaus were avoided and 100% removal of dioxane observed. By using14C-labeled dioxane, we show that ∼40% of the dioxane carbon is mineralized within 6 d. These data support the use of slow-release persulfate and zerovalent iron to treat dioxane-contaminated water.

Original languageEnglish (US)
Pages (from-to)170-177
Number of pages8
JournalChemosphere
Volume175
DOIs
StatePublished - 2017

Keywords

  • Chlorinated solvents
  • Dioxane
  • Persulfate
  • Slow-release oxidants
  • TCE

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

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