Nanoscale zero-valent iron (nZVI) activated three common peroxides (persulfate (PS), peroxymonosulfate (PMS) and hydrogen peroxide (HP)) were evaluated for 1,4-dioxane(1,4-D) and arsenite (As(III)) removal. The 1,4-D and As(III) are the main contaminants of groundwater released from the various industries. The ex- or in-situ chemical oxidation processes are used to mineralize 1,4-D and oxidize As(III). Peroxide oxidants are capable of producing radicals when they are coupled with ferrous ion (Fe2+), with their own oxidizing ability. nZVI was used as an alternative to release Fe2+ slowly lowering scavenger effect of Fe2+ and adsorbent for the arsenic species. The order of removal efficiencies were PS &gt; HP &gt; PMS. The main produced radical was hydroxyl radical (OH, E0 = 2.70 V), while sulfate radical (SO4-, E0 = 2.60 V) contributed partially. In case of As(III) removal, radical scavengers didn’t significantly affect removal efficiencies suggesting the main removal mechanism is not an oxidation with radicals, rather by oxidants. The pH 3 was optimum pH for these systems dissolving Fe2+ from nZVI. The Fe2+ dissolution was promoted with three oxidants especially with PS and PMS. The promotion would be caused by SO42- produced from PS and PMS. The promoted corrosion by oxidant could accelerate the iron (hydr)oxides formation which has high affinity with As species. The knowledge gained from this study aids in selecting proper oxidant used with nZVI to purify water/wastewater contaminated by organic/inorganic contaminants.

Comparing removal efficiencies of 1,4-dioxane and arsenite by nZVI-common oxidants system: Persulfate, peroxymonosulfate and hydrogen peroxide

253rd National Meeting (2017)

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