کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6365639 | 1623082 | 2015 | 8 صفحه PDF | دانلود رایگان |
- Polyphosphates greatly increase oxidant yields from nZVI and Fe(II) with oxygen.
- The oxidant yields are similar in the nZVI/O2 and the Fe(II)/O2 systems with TPP present.
- The oxidant yields of over 50% suggest a new short pathway for oxidant production.
- Fe(IV) complexes appears to be the dominant oxidants rather than hydroxyl radicals.
The production of reactive oxidants from nanoparticulate zero-valent iron (nZVI) and ferrous ion (Fe(II)) in the presence of oxygen was greatly enhanced by the addition of tetrapolyphosphate (TPP) as an iron-chelating agent. Compared to other ligands, TPP exhibited superior activity in improving the oxidant yields. The nZVI/TPP/O2 and the Fe(II)/TPP/O2 systems showed similar oxidant yields with respect to the iron consumed, indicating that nZVI only serves as a source of Fe(II). The degradation efficacies of selected organic compounds were also similar in the two systems. It appeared that both hydroxyl radical (OH) and ferryl ion (Fe(IV)) are produced, and OH dominates at acidic pH. However, at pHÂ >Â 6, little occurrence of hydroxylated oxidation products suggests that Fe(IV) is a dominant oxidant. The degradation rates of selected organic compounds by the Fe(II)/TPP/O2 system had two optimum points at pH 6 and 9, and these pH-dependent trends are likely attributed to the speciation of Fe(IV) with different reactivities.
Journal: Water Research - Volume 86, 1 December 2015, Pages 66-73