TY - JOUR
T1 - Enhanced decomposition of caffeine by water plasma combined with mist generator
T2 - Effect of operational parameter and decomposition pathway
AU - Kim, Soon Ho
AU - Tanaka, Manabu
AU - Lee, Myeong Hoon
AU - Watanabe, Takayuki
N1 - Funding Information:
This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. JP19H01887 , JP18H03856 ) and the Japan Science and Technology Agency (JST) SPRING ( JPMJSP2136 ). We also thank the Center of Advanced Instrumental Analysis, Kyushu University for assistance with the ESI-MS measurements.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/11
Y1 - 2022/11
N2 - Water plasma coupled with mist generator was introduced to perform the decomposition of caffeine (CAF) wastewater. The mist-shaped water molecule was directly used for plasma-forming gas with no additional gas. The influence of arc current on the decomposition of CAF was elucidated in detail. With the increase of input power from 0.8 to 1.1 kW according to arc current, the removal efficiency of total organic carbon (TOC) and CAF increased, reaching 91.1 and 99.8% at 9.5 A, respectively. H2, CO, CO2, and N2 were major effluent gaseous species, of which the H2 generation was more than 40% for all conditions. The concentration of nitrate in the effluent liquids was the highest at 9.5 A due to a higher oxidation environment. The H, O, and OH as reactive species formed via the dissociation of water molecules were demonstrated, and the plasma temperatures were at over 5000 K. The detailed decomposition pathway was deduced based on eleven intermediate products identified in this process. Electron impact and hydroxyl radical were found to take leading roles in the decomposition of CAF.
AB - Water plasma coupled with mist generator was introduced to perform the decomposition of caffeine (CAF) wastewater. The mist-shaped water molecule was directly used for plasma-forming gas with no additional gas. The influence of arc current on the decomposition of CAF was elucidated in detail. With the increase of input power from 0.8 to 1.1 kW according to arc current, the removal efficiency of total organic carbon (TOC) and CAF increased, reaching 91.1 and 99.8% at 9.5 A, respectively. H2, CO, CO2, and N2 were major effluent gaseous species, of which the H2 generation was more than 40% for all conditions. The concentration of nitrate in the effluent liquids was the highest at 9.5 A due to a higher oxidation environment. The H, O, and OH as reactive species formed via the dissociation of water molecules were demonstrated, and the plasma temperatures were at over 5000 K. The detailed decomposition pathway was deduced based on eleven intermediate products identified in this process. Electron impact and hydroxyl radical were found to take leading roles in the decomposition of CAF.
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U2 - 10.1016/j.chemosphere.2022.136056
DO - 10.1016/j.chemosphere.2022.136056
M3 - Article
C2 - 35973502
AN - SCOPUS:85135941051
SN - 0045-6535
VL - 307
JO - Chemosphere
JF - Chemosphere
M1 - 136056
ER -
