TY - JOUR
T1 - Production of perchlorate by laboratory simulated lightning process
AU - Rao, Balaji
AU - Mohan, Suhas
AU - Neuber, Andreas
AU - Jackson, William Andrew
N1 - Funding Information:
Acknowledgments This study was supported by the Department of Defense Strategic Environmental Research and Development Program (SERDP, EP-1435). We thank the people at the Center for Pulsed Power and Power Electronics at Texas Tech University for donating the high-voltage power supply device for the lightning simulation experiments.
PY - 2012/1
Y1 - 2012/1
N2 - Perchlorate (ClO 4 -), a thyroid hormone disruptor, is both naturally occurring and a manmade contaminant increasingly found in a variety of terrestrial environments. The environmental presence of ClO 4 - is considered to be the result of atmospheric formation and deposition processes. The ultimate processes, particularly heterogeneous-based reactions, leading to natural ClO 4 - formation are not well understood. Oxidation of chlorine species by an energetic source such as lightning is considered to be one of the potential heterogeneous sources of natural ClO 4 -. Currently, there is very little information available on lightning-induced ClO 4 -. We designed a laboratory electrical discharge reactor capable of evaluating ClO 4 - formation by the oxidation of "dry" sodium chloride (NaCl) aerosols (relative humidity (RH) <70%) in electrical discharge plasma at voltages and energies up to 24 kV and 21 kJ, respectively. Similar to other non-electrochemical ClO 4 - production processes, the amount of ClO 4 - produced (0.5-4.8 μg) was 3 orders of magnitude lower than the input Cl - (7.1-60.1 mg). The amount of ClO 4 - generated increased with peak voltage (V) and theoretical maximum discharge energy with ΔClO 4 -/ΔV=0.28× 10-3 μg V -1 (R 2=0.94) and ΔClO 4 -/ΔE=0.44× 10-3 μg J -1 (R 2=0.83). The total ClO 4 - generated decreased with an increase in relative humidity from 2.8±0.1 μg (RH̃46%) to 0.9±0.1 μg (RH̃62%) indicating that the presence of moisture inhibits the formation of ClO 4 -. Additional modifications to the reactor support the hypothesis of ClO 4 - formation due to the action of plasma on Cl - aerosols as opposed to direct oxidation on the surface of the electrodes. Finally, the contribution of lightning-induced ClO 4 - in North America is calculated to have a wide range from 0.006×10 5 to 5×10 5 kg/year and is within the range of the measured ClO 4 - depositional flux in precipitation samples obtained across the USA (0.09× 105-1.2×10 5 kg/y).
AB - Perchlorate (ClO 4 -), a thyroid hormone disruptor, is both naturally occurring and a manmade contaminant increasingly found in a variety of terrestrial environments. The environmental presence of ClO 4 - is considered to be the result of atmospheric formation and deposition processes. The ultimate processes, particularly heterogeneous-based reactions, leading to natural ClO 4 - formation are not well understood. Oxidation of chlorine species by an energetic source such as lightning is considered to be one of the potential heterogeneous sources of natural ClO 4 -. Currently, there is very little information available on lightning-induced ClO 4 -. We designed a laboratory electrical discharge reactor capable of evaluating ClO 4 - formation by the oxidation of "dry" sodium chloride (NaCl) aerosols (relative humidity (RH) <70%) in electrical discharge plasma at voltages and energies up to 24 kV and 21 kJ, respectively. Similar to other non-electrochemical ClO 4 - production processes, the amount of ClO 4 - produced (0.5-4.8 μg) was 3 orders of magnitude lower than the input Cl - (7.1-60.1 mg). The amount of ClO 4 - generated increased with peak voltage (V) and theoretical maximum discharge energy with ΔClO 4 -/ΔV=0.28× 10-3 μg V -1 (R 2=0.94) and ΔClO 4 -/ΔE=0.44× 10-3 μg J -1 (R 2=0.83). The total ClO 4 - generated decreased with an increase in relative humidity from 2.8±0.1 μg (RH̃46%) to 0.9±0.1 μg (RH̃62%) indicating that the presence of moisture inhibits the formation of ClO 4 -. Additional modifications to the reactor support the hypothesis of ClO 4 - formation due to the action of plasma on Cl - aerosols as opposed to direct oxidation on the surface of the electrodes. Finally, the contribution of lightning-induced ClO 4 - in North America is calculated to have a wide range from 0.006×10 5 to 5×10 5 kg/year and is within the range of the measured ClO 4 - depositional flux in precipitation samples obtained across the USA (0.09× 105-1.2×10 5 kg/y).
KW - Deposition
KW - Lightning
KW - Natural
KW - Perchlorate
UR - http://www.scopus.com/inward/record.url?scp=84856553004&partnerID=8YFLogxK
U2 - 10.1007/s11270-011-0857-y
DO - 10.1007/s11270-011-0857-y
M3 - Article
AN - SCOPUS:84856553004
SN - 0049-6979
VL - 223
SP - 275
EP - 287
JO - Water, Air, and Soil Pollution
JF - Water, Air, and Soil Pollution
IS - 1
ER -