Arsenite oxidation initiated by the uv photolysis of nitrite and nitrate

Dong Hyo Kim, Jaesang Lee, Jungho Ryu, Kitae Kim, Wonyong Choi

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

This study demonstrates that the production of reactive oxidizing species (e.g., hydroxyl radical (•OH)) during the photolysis of nitrite (NO 2 -) or nitrate (NO3 -) leads to the oxidative conversion of arsenite (As(III)) to arsenate (As(V)). While the direct UV photolytic oxidation of As(III) was absent, nitrite (20 or 200 μM) addition markedly accelerated the oxidation of As(III) under UV irradiation (> 295 nm), which implies a role of NO2 - as a photosensitizer for As(III) oxidation. Nitrate-mediated photooxidation of As(III) revealed an initial lag phase during which NO3 - is converted into NO2 -. UV-Photosensitized oxidation of As(III) was kinetically enhanced under acidic pH condition where nitrous acid (HNO2) with a high quantum yield for •OH production is a predominant form of nitrite. On the other hand, alkaline pH that favors the photoinduced transformation of NO3 - to NO2 - significantly facilitated the catalytic reduction/oxidation cycling, which enabled the complete oxidation of As(III) at the condition of [As(III)]/[NO2 -] ≫ 1 and markedly accelerated NO 3 --sensitized oxidation of As(III) the presence of O 2 and N2O as electron scavengers enhanced the photochemical dissociation of NO2 - via intermolecular electron transfer, initiating the oxidative As(III) conversion route probably involving NO2• and superoxide radical anion (O 2-) as alternative oxidants the outdoor experiment demonstrated the capability of NO2 - for the photosensitized production of oxidizing species and the subsequent oxidation of As(III) into As(V) under solar irradiation.

Original languageEnglish
Pages (from-to)4030-4037
Number of pages8
JournalEnvironmental Science and Technology
Volume48
Issue number7
DOIs
Publication statusPublished - 2014 Apr 1

Fingerprint

arsenite
Photolysis
Nitrites
photolysis
Nitrates
nitrite
nitrate
oxidation
Superoxides
Oxidation
Nitrous Acid
Electrons
Photosensitizing Agents
Oxidants
Hydroxyl Radical
irradiation
electron
Irradiation
photooxidation
scavenger

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Arsenite oxidation initiated by the uv photolysis of nitrite and nitrate. / Kim, Dong Hyo; Lee, Jaesang; Ryu, Jungho; Kim, Kitae; Choi, Wonyong.

In: Environmental Science and Technology, Vol. 48, No. 7, 01.04.2014, p. 4030-4037.

Research output: Contribution to journalArticle

Kim, Dong Hyo ; Lee, Jaesang ; Ryu, Jungho ; Kim, Kitae ; Choi, Wonyong. / Arsenite oxidation initiated by the uv photolysis of nitrite and nitrate. In: Environmental Science and Technology. 2014 ; Vol. 48, No. 7. pp. 4030-4037.
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