Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions
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- Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions
- Jeong, Daun
Min, Dae Wi
- Engineering; Environmental Sciences & Ecology
- Issue Date
- Jeong, Daun., et al. 2015. Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions, Environmental Science & Technology, 49: 12816-12822.
- Dissolution of iron from mineral dust particles greatly
depends upon the type and amount of copresent inorganic anions. In this
study, we investigated the roles of sulfate, chloride, nitrate, and perchlorate
on the dissolution of maghemite and lepidocrocite in ice under both dark
and UV irradiation and compared the results with those of their aqueous
counterparts. After 96 h of reaction, the total dissolved iron in ice (pH 3
before freezing) was higher than that in the aqueous phase (pH 3) by
6-28 times and 10-20 times under dark and UV irradiation, respectively.
Sulfuric acid was the most efficient in producing labile iron under dark
condition, whereas hydrochloric acid induced the most dissolution of the
total and ferrous iron in the presence of light. This ice-induced dissolution
result was also confirmed with Arizona Test Dust (AZTD). In the freeze-
thaw cycling test, the iron oxide samples containing chloride, nitrate,
or perchlorate showed a similar extent of total dissolved iron after each
cycling while the sulfate-containing sample rapidly lost its dissolution activity with repeating the cycle. This unique phenomenon
observed in ice might be related to the freeze concentration of protons, iron oxides, and inorganic anions in the liquid-like ice grain
boundary region. These results suggest that the ice-enhanced dissolution of iron oxides can be a potential source of bioavailable iron,
and the acid anions critically influence this process.
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