Nitro-aromatic compounds(NACs)are among the major components of brown carbon(BrC)in the atmosphere,causing negative impacts on regional climate,air quality,and ecological health.Due to the extensive origins,it is stil...Nitro-aromatic compounds(NACs)are among the major components of brown carbon(BrC)in the atmosphere,causing negative impacts on regional climate,air quality,and ecological health.Due to the extensive origins,it is still a challenge to figure out the contributions and originating regions for different sources of atmospheric NACs.Here,field observations on fine particulate NACs were conducted at a coastal rural area in Qingdao,China in the winter of 2018 and 2019.The mean total concentrations of fine particulate nitro-aromatic compounds were 125.0±89.5 and 27.7±21.1 ng/m^(3)in the winter of 2018 and 2019,respectively.Among the measured eleven NACs,nitrophenols and nitrocatechols were the most abundant species.Variation characteristics and correlation analysis showed that humidity and anthropogenic primary emissions had significant influences on the NAC abundances.In this study,two tracing methods of the improved spatial concentration weighted trajectory(SCWT)model and the receptor model of positive matrix factorization(PMF)were combined to comprehensively understand the origins of NACs in fine particles at coastal Qingdao.Four major sources were identified,including coal combustion,biomass burning,vehicle exhaust,and secondary formation.Surprisingly,coal combustion was responsible for about half of the observed nitro-aromatic compounds,followed by biomass burning(~30%).The results by SCWT demonstrated that the coal combustion dominated NACs mainly originated from the Shandong peninsula and the areas to the north and southwest,while those dominated by biomass burning primarily came from local Qingdao and the areas to the west.展开更多
Fenton and ozone treatment was investigated at laboratory scale for the degradation of aqueous solutions of nitrobenzene （NB）. Effects of reactants concentration （O3, H2O2, and Fe（Ⅱ））, temperature, and pH on NB...Fenton and ozone treatment was investigated at laboratory scale for the degradation of aqueous solutions of nitrobenzene （NB）. Effects of reactants concentration （O3, H2O2, and Fe（Ⅱ））, temperature, and pH on NB degradation were monitored. Reaction kinetic of these processes was also assessed. A rapid reaction took place for Fenton process at higher initial concentration of H2O2, higher temperatures, and more acidic conditions （pH 3）. Similarly, ozonation reaction exhibited rapid rates for higher ozone dose, higher temperatures, and more basic conditions （pH 11）. Complete NB degradation in 65 min was achieved using Fenton process. The conditions of complete elimination of 100 mg/L of initial NB concentration, were 250 mg/L of H202 concentration, pH 3, and 10 mg/L of Fe（Ⅱ） concentration. Under these conditions, 55% organic carbon elimination was achieved. Total organic carbon mineralization was attained in 240 rain reaction time by Fenton process with 900 mg/L of H202 concentration, and 30 mg/L of Fe（Ⅱ） concentration. Fenton reaction showed a pseudo-first order kinetic; the reaction rate constant was ranged from 0.0226 to 0.0658 min^-1. Complete NB degradation was also achieved for an ozone dose of the order of 2.5 g/L. The ozonation was studied at different ozone doses, different initial pH （7-11） and at different temperatures （15-35℃）. NB ozonation kinetic was represented by a bi-molecular kinetic model which was reduced to pseudo-first order kinetic. The pseudo-first order reaction rate constant was determined to increase at 20℃ from 0.004 to 0.020 min^-1 as the used ozone increased from 0.4 to 1.9 g/L.展开更多
Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/...Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/TiO2/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO2/dye-sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% ofp-nitrotoluene could be photocatalytically reduced into p-toluidine. In the Vis/TiO2/dye-sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.展开更多
基金supported by the Natural Science Foundation of Shandong Province (No.ZR2020YQ30)the National Natural Science Foundation of China (Nos.42005089,41775118)+1 种基金the Youth Innovation Program of Universities in Shandong Province (No.2019KJD007)received financial support from Shandong University (No.2020QNQT012)。
文摘Nitro-aromatic compounds(NACs)are among the major components of brown carbon(BrC)in the atmosphere,causing negative impacts on regional climate,air quality,and ecological health.Due to the extensive origins,it is still a challenge to figure out the contributions and originating regions for different sources of atmospheric NACs.Here,field observations on fine particulate NACs were conducted at a coastal rural area in Qingdao,China in the winter of 2018 and 2019.The mean total concentrations of fine particulate nitro-aromatic compounds were 125.0±89.5 and 27.7±21.1 ng/m^(3)in the winter of 2018 and 2019,respectively.Among the measured eleven NACs,nitrophenols and nitrocatechols were the most abundant species.Variation characteristics and correlation analysis showed that humidity and anthropogenic primary emissions had significant influences on the NAC abundances.In this study,two tracing methods of the improved spatial concentration weighted trajectory(SCWT)model and the receptor model of positive matrix factorization(PMF)were combined to comprehensively understand the origins of NACs in fine particles at coastal Qingdao.Four major sources were identified,including coal combustion,biomass burning,vehicle exhaust,and secondary formation.Surprisingly,coal combustion was responsible for about half of the observed nitro-aromatic compounds,followed by biomass burning(~30%).The results by SCWT demonstrated that the coal combustion dominated NACs mainly originated from the Shandong peninsula and the areas to the north and southwest,while those dominated by biomass burning primarily came from local Qingdao and the areas to the west.
文摘Fenton and ozone treatment was investigated at laboratory scale for the degradation of aqueous solutions of nitrobenzene （NB）. Effects of reactants concentration （O3, H2O2, and Fe（Ⅱ））, temperature, and pH on NB degradation were monitored. Reaction kinetic of these processes was also assessed. A rapid reaction took place for Fenton process at higher initial concentration of H2O2, higher temperatures, and more acidic conditions （pH 3）. Similarly, ozonation reaction exhibited rapid rates for higher ozone dose, higher temperatures, and more basic conditions （pH 11）. Complete NB degradation in 65 min was achieved using Fenton process. The conditions of complete elimination of 100 mg/L of initial NB concentration, were 250 mg/L of H202 concentration, pH 3, and 10 mg/L of Fe（Ⅱ） concentration. Under these conditions, 55% organic carbon elimination was achieved. Total organic carbon mineralization was attained in 240 rain reaction time by Fenton process with 900 mg/L of H202 concentration, and 30 mg/L of Fe（Ⅱ） concentration. Fenton reaction showed a pseudo-first order kinetic; the reaction rate constant was ranged from 0.0226 to 0.0658 min^-1. Complete NB degradation was also achieved for an ozone dose of the order of 2.5 g/L. The ozonation was studied at different ozone doses, different initial pH （7-11） and at different temperatures （15-35℃）. NB ozonation kinetic was represented by a bi-molecular kinetic model which was reduced to pseudo-first order kinetic. The pseudo-first order reaction rate constant was determined to increase at 20℃ from 0.004 to 0.020 min^-1 as the used ozone increased from 0.4 to 1.9 g/L.
基金Project supported by the National Natural Science Foundation of China （Nos. 20673042, 20973071） and the Key Project of Science and Technology Research of Ministry of Education of China （208062）.
文摘Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/TiO2/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO2/dye-sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% ofp-nitrotoluene could be photocatalytically reduced into p-toluidine. In the Vis/TiO2/dye-sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.
