The distribution and source of the solvent-extractable organic and inorganic components in PM2.5 （aerodynamics equivalent diameter below 2.5 microns）, and PM10 （aerodynamics equivalent diameter below 10 microns） f...The distribution and source of the solvent-extractable organic and inorganic components in PM2.5 （aerodynamics equivalent diameter below 2.5 microns）, and PM10 （aerodynamics equivalent diameter below 10 microns） fractions of airborne particles were studied weekly from September 2006 to August 2007 in Beijing. The extracted organic and inorganic compounds identified in both particle size ranges consisted of n-alkanes, PAHs （polycyclic aromatic hydrocarbons）, fatty acids and water soluble ions. The potential emission sources of these organic compounds were reconciled by combining the values of n-alkane carbon preference index （CPI）, %waxCn, selected diagnostic ratios of PAHs and principal component analysis in both size ranges. The mean cumulative concentrations of n-alkanes reached 1128.65 ng/m3 in Beijing, 74% of which （i.e., 831.7 ng/m3） was in the PM2.5 fraction, PAHs reached 136.45 ng/m3 （113.44 ng/m3 or 83% in PM2.5）, and fatty acids reached 436.99 ng/m3 （324.41 ng/m3 or 74% in PM2.5）, which resulted in overall enrichment in the fine particles. The average concentrations of SO42-, NO3-, and NH4＋ were 21.3 ± 15.2, 6.1 ±1.8, 12.5 ± 6.1 μg/m3 in PM2.5, and 25.8±15.5, 8.9± 2.6, 16.9±9.5 μg/m3 in PM10, respectively. These three secondary ions primarily existed as ammonium sulfate （（NH4）2SO4）, ammonium bisulfate （NH4HSO4） and ammonium nitrate （NH4NO3）. The characteristic ratios of PAHs revealed that the primary sources of PAHs were coal combustion, followed by gasoline combustion. The ratios of stearic/palmitic acid indicated the major contribution of vehicle emissions to fatty acids in airborne particles. The major alkane sources were biogenic sources and fossil fuel combustion. The major sources of PAHs were vehicular emission and coal combustion.展开更多
As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to ...As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles （nanobuhbles and microbubbles） on the flotation of fine （-38 ＋ 14.36 μm） and ultrafine （-14.36 ＋ 5μm） chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nano- microbubble generator based on the cavitation phenomenon in Venturi tubes. In order to better under- stand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nano- bubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16-21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles （-14.36 ＋ 5 μm） more than that of fine particles （-38 ＋ 14.36 μm）. Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%, respectively.展开更多
Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present st...Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present study,we chose four typical kinds of indoor and outdoor environments with the longest average human residence times to assess the human exposure in Hangzhou,including newly decorated residences,ordinary residences,offices and outdoor air.In order to analyze the pollution levels and characteristics of 15 gasand particle-phase PAEs in indoor and outdoor environments,air and particulate samples were collected simultaneously.The total PAEs concentrations in the four types of environments were 25,396,25,466.8,15,388.8 and 3616.2 ng/m^3,respectively.DEHP and DEP were the most abundant,and DMPP was at the lowest level.Distinct variations in the distributions of indoor/outdoor,gas/particle-phase and different molecular weights of PAEs were observed,showing that indoor environments were the main sources of PAEs pollution.While most PAEs tended to exsit in indoor sites and gas-phase,the high-molecular-weight chemicals tended to exist in the particle-phase and were mainly found in PM2.5.PAEs were more likely adsorbed by small particles,especially for the indoor environments.There existed a good correlation between the particle matter concentrations and the PAEs levels.In addition,neither temperature nor humidity had obvious effects on the distributions of the PAEs concentrations.展开更多
基金supported by the Science and Technology Project of Beijing (No. D09040903670902)the Chinese Academy of Sciences for Key Topics in Innovation Engineering (No. KZCX2-YW-Q02-03)the Basic Research and Development Program (973) of China (No.2007CB407303)
文摘The distribution and source of the solvent-extractable organic and inorganic components in PM2.5 （aerodynamics equivalent diameter below 2.5 microns）, and PM10 （aerodynamics equivalent diameter below 10 microns） fractions of airborne particles were studied weekly from September 2006 to August 2007 in Beijing. The extracted organic and inorganic compounds identified in both particle size ranges consisted of n-alkanes, PAHs （polycyclic aromatic hydrocarbons）, fatty acids and water soluble ions. The potential emission sources of these organic compounds were reconciled by combining the values of n-alkane carbon preference index （CPI）, %waxCn, selected diagnostic ratios of PAHs and principal component analysis in both size ranges. The mean cumulative concentrations of n-alkanes reached 1128.65 ng/m3 in Beijing, 74% of which （i.e., 831.7 ng/m3） was in the PM2.5 fraction, PAHs reached 136.45 ng/m3 （113.44 ng/m3 or 83% in PM2.5）, and fatty acids reached 436.99 ng/m3 （324.41 ng/m3 or 74% in PM2.5）, which resulted in overall enrichment in the fine particles. The average concentrations of SO42-, NO3-, and NH4＋ were 21.3 ± 15.2, 6.1 ±1.8, 12.5 ± 6.1 μg/m3 in PM2.5, and 25.8±15.5, 8.9± 2.6, 16.9±9.5 μg/m3 in PM10, respectively. These three secondary ions primarily existed as ammonium sulfate （（NH4）2SO4）, ammonium bisulfate （NH4HSO4） and ammonium nitrate （NH4NO3）. The characteristic ratios of PAHs revealed that the primary sources of PAHs were coal combustion, followed by gasoline combustion. The ratios of stearic/palmitic acid indicated the major contribution of vehicle emissions to fatty acids in airborne particles. The major alkane sources were biogenic sources and fossil fuel combustion. The major sources of PAHs were vehicular emission and coal combustion.
基金the Tarbiat Modares University (TMU), the Iran Mineral Processing Research Center (IMPRC) and the IMIDRO for the technical assistance and financial support
文摘As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles （nanobuhbles and microbubbles） on the flotation of fine （-38 ＋ 14.36 μm） and ultrafine （-14.36 ＋ 5μm） chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nano- microbubble generator based on the cavitation phenomenon in Venturi tubes. In order to better under- stand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nano- bubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16-21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles （-14.36 ＋ 5 μm） more than that of fine particles （-38 ＋ 14.36 μm）. Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%, respectively.
基金supported by the National Key R&D Program of China (No. 2016YFC0207103)the National Natural Science Foundation of China (No. 21607127)the Brain Bridge project with Koninklijke Philips N.V. (No. BB3-2016-01)
文摘Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present study,we chose four typical kinds of indoor and outdoor environments with the longest average human residence times to assess the human exposure in Hangzhou,including newly decorated residences,ordinary residences,offices and outdoor air.In order to analyze the pollution levels and characteristics of 15 gasand particle-phase PAEs in indoor and outdoor environments,air and particulate samples were collected simultaneously.The total PAEs concentrations in the four types of environments were 25,396,25,466.8,15,388.8 and 3616.2 ng/m^3,respectively.DEHP and DEP were the most abundant,and DMPP was at the lowest level.Distinct variations in the distributions of indoor/outdoor,gas/particle-phase and different molecular weights of PAEs were observed,showing that indoor environments were the main sources of PAEs pollution.While most PAEs tended to exsit in indoor sites and gas-phase,the high-molecular-weight chemicals tended to exist in the particle-phase and were mainly found in PM2.5.PAEs were more likely adsorbed by small particles,especially for the indoor environments.There existed a good correlation between the particle matter concentrations and the PAEs levels.In addition,neither temperature nor humidity had obvious effects on the distributions of the PAEs concentrations.
