title: Polyphosphate-enhanced production of reactive oxidants by nanoparticulate zero-valent iron and ferrous ion in the presence of oxygen: Yield and nature of oxidants.
abstract: 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 pH > 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.
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 689-798, Republic of Korea.
authors.forename: Hak-Hyeon
authors.initials: HH
authors.lastname: Kim
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 689-798, Republic of Korea.
authors.forename: Hongshin
authors.initials: H
authors.lastname: Lee
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 689-798, Republic of Korea.
authors.forename: Hyung-Eun
authors.initials: HE
authors.lastname: Kim
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 689-798, Republic of Korea.
authors.forename: Jiwon
authors.initials: J
authors.lastname: Seo
authors.affiliation: Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14 gil, Seongbuk-gu, Seoul, 136-791, Republic of Korea.
authors.forename: Seok Won
authors.initials: SW
authors.lastname: Hong
authors.affiliation: Southeast Sea Fisheries Research Center, National Fisheries Research and Development Institute (NFRDI), 397-68, Sanyangilju-ro, Sanyang-eup, Tongyeong-si, Gyeongsangnam-do, 650-943, Republic of Korea.
authors.forename: Jeong-Yong
authors.initials: JY
authors.lastname: Lee
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 689-798, Republic of Korea. Electronic address: clee@unist.ac.kr.
authors.forename: Changha
authors.initials: C
authors.lastname: Lee
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011122:Polyphosphates / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D008024:Ligands; D016877:Oxidants; D011122:Polyphosphates; C066317:ferryl iron; D017665:Hydroxyl Radical; D007501:Iron; D010100:Oxygen
keywords: Advanced oxidation; Ferrous ion; Nanoparticulate zero-valent iron; Oxygen activation; Polyphosphate