TY - JOUR
T1 - Photochemical formation of perchlorate from aqueous oxychlorine anions
AU - Kang, Namgoo
AU - Anderson, Todd A.
AU - Andrew Jackson, W.
N1 - Funding Information:
This work was supported by the Strategic Environmental Research and Development Program (SERDP) of the U.S. Department of Defense through Contract EP-1845. The authors thank Frank Wyatt and Doug Haynes for manufacturing a merry-go-round sample holder and solar radiation experimental units. The authors also thank Dr. Jaclyn Cañas and Brad Thornhill for technical assistance with the IC analyses.
PY - 2006/5/10
Y1 - 2006/5/10
N2 - Evidence of atmospherically produced perchlorate is being accumulated, yet information regarding its formation process is largely unknown. For the first time, the present study demonstrates that perchlorate can be generated as an end-product of photochemical transformation reactions of chlorine precursors such as aqueous salt solutions of hypochlorite, chlorite, and chlorate upon exposure to ultraviolet (UV) radiation. For example, under exposure to UV light from photochemical reactor lamps at a peak wavelength of 253.7 nm for 7 days, the observed perchlorate concentrations were 5, 25, and 626 μg/L at initial chlorite concentrations of 100, 1000, and 10,000 mg/L, respectively. In addition, perchlorate was generated within 7 days from aqueous chlorite solutions at mid-latitude (33°59′N, 101°89′W) spring and summer solar radiation. Via UV radiation from the artificial lamps and sunlight, chlorite was converted to chloride (68%) and chlorate (32%) as end-products on the basis of molar percentage. However, perchlorate was not detected from aqueous chloride solutions at initial concentrations up to 10,000 mg/L under the experimental conditions. Relevant mechanistic pathways were proposed based on the fact that chlorine dioxide (as a primary intermediate) may play a significant role in phototransformation of the precursors leading to perchlorate.
AB - Evidence of atmospherically produced perchlorate is being accumulated, yet information regarding its formation process is largely unknown. For the first time, the present study demonstrates that perchlorate can be generated as an end-product of photochemical transformation reactions of chlorine precursors such as aqueous salt solutions of hypochlorite, chlorite, and chlorate upon exposure to ultraviolet (UV) radiation. For example, under exposure to UV light from photochemical reactor lamps at a peak wavelength of 253.7 nm for 7 days, the observed perchlorate concentrations were 5, 25, and 626 μg/L at initial chlorite concentrations of 100, 1000, and 10,000 mg/L, respectively. In addition, perchlorate was generated within 7 days from aqueous chlorite solutions at mid-latitude (33°59′N, 101°89′W) spring and summer solar radiation. Via UV radiation from the artificial lamps and sunlight, chlorite was converted to chloride (68%) and chlorate (32%) as end-products on the basis of molar percentage. However, perchlorate was not detected from aqueous chloride solutions at initial concentrations up to 10,000 mg/L under the experimental conditions. Relevant mechanistic pathways were proposed based on the fact that chlorine dioxide (as a primary intermediate) may play a significant role in phototransformation of the precursors leading to perchlorate.
KW - Photochemistry
KW - Photodecomposition
KW - Precursor
KW - Radiation
KW - Sunlight
KW - UV
UR - http://www.scopus.com/inward/record.url?scp=33646369361&partnerID=8YFLogxK
U2 - 10.1016/j.aca.2006.01.085
DO - 10.1016/j.aca.2006.01.085
M3 - Article
C2 - 17723378
AN - SCOPUS:33646369361
SN - 0003-2670
VL - 567
SP - 48
EP - 56
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
IS - 1 SPEC. ISS.
ER -