The effect of coal size on PM2.5 and PM-bound polycyclic aromatic hydrocarbon (PAH) emissions from a domestic natural cross-draft stove

Residential coal combustion has played an important role in the domestic energy supply of Northern China for many decades and will do so for the foreseeable future, although it is also an important contributor to severe air pollution. Meeting the daily cooking and spacing-heating demands of rural residents in an eco-friendly manner necessitates cleaner-burning technologies for residential coal combustion. Several reports have suggested that appropriately sized coal be beneficial for optimizing the performance of domestic coal-fired stoves. The effects of coal size (<1.6 cm, 1.6–2.0 cm, 2.0–2.5 cm and >2.5 cm) on fine particulate matter (PM_2.5) and sixteen U.S. Environmental Protection Agency (EPA) priority polycyclic aromatic hydrocarbons (16-PAHs) emissions from a natural cross-draft stove, operating in different phases (ignition, high power heating, low power heating, ramping up and high power cooking) were analyzed in this study. Results indicated that decreasing the coal size enhanced thermal efficiency and reduced pollutant emissions. When the coal size decreased from >2.5 cm to <1.6 cm, the average emission factor (EF) of PM_2.5 over a complete combustion sequence decreased from 3.12 to 1.42 mg/MJ_net, and the EF of PM-bound total PAHs decreased from 44.9 to 10.9 μg/MJ_net. The corresponding toxic equivalent quantity (TEQ) decreased from 1.25 to 0.38 μg/MJ_net. Emissions and energy efficiencies varied markedly between the various combustion phases, adequate air supply during the high power heating and cooking phases reduced the EFs of PM_2.5 and PAHs, while the low power heating phase produced relatively more pollutants due to a fuel-rich condition.     

Removal of naphthalene from aqueous solution on chemically modified activated carbons

The aim of this work was to correlate the textural and chemical features of carbonaceous adsorbents with the adsorption capacity of naphthalene from aqueous phase, at the concentration in which this compound is usually found in wastewater from coke ovens. The study reveals that the adsorption capacity in different carbon materials depends not only on the textural characteristics of the material but also on the functionalities of the activated carbons. The micropores of the adsorbents, particularly those of narrower diameter, were found to be active sites for the retention of naphthalene. In contrast, the modification of the surface chemistry of the carbon materials led to a decrease in the adsorption capacities. Dispersive forces play an important role, and adsorbents with a higher non-polar character have proven to be more efficient for the naphthalene adsorption. This behaviour has been linked to the presence of specific interactions between the basal planes and the polyaromatic structure of the naphthalene molecule.     

Vapour-phase and particulate-bound PAHs profile generated by a (SI/HCCI) engine from a winter grade commercial gasoline fuel

The vapour-phase and particulate-bound Aromatic Hydrocarbons, PAHs, generated by a V6 gasoline engine working in spark-ignition (SI) and homogeneous charge compression ignition (HCCI) modes were collected and analysed. All data were obtained during steady-state, fully warmed-up operation at different engine power levels (low and medium loads and mid-speed), and two different engine operation modes (SI and HCCI). The fuel used in this study was winter grade commercial gasoline fuel.The vapour-phase exhaust gases were passed through stainless-steel cartridges containing XAD-2 resin to capture PAHs. The PAHs were extracted from the resin with dichloromethane in an ultrasonic bath, the obtained extracts were later analysed qualitatively and quantitatively by GC-MS. The vapour-phase PAHs compounds observed from HCCI mode operated in low load were Naphthalene, Acenaphthylene and Acenaphthene only, while that obtained from SI mode under low load were Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Anthracene, Phenanthrene, Fluoranthene and Pyrene.The PAHs bound to particulates were trapped by using a complex of dilution tunnels with filter papers. The soluble organic fractions (SOF) of the trapped particulates were separated from the insoluble fraction (ISF) with the help of ultrasonic elution, and analysed by GC-MS method. The most abundant PAHs detected under selected operation condition for HCCI mode was Benzo[a]anthracene, followed by Chrysene, then Pyrene and pursued by Benzo[b]fluoranthene, in SI mode under same operation condition the highest PAH detected was Benzo[a]anthracene followed by Pyrene, Benzo[b]fluoranthene and Chrysene. Probable mechanisms for the production of some of the pyrosynthetic PAH were discussed.     

Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Atmospheric Environment of Urban Areas in Latin America

Polycyclic aromatic hydrocarbons (PAHs) are chemical compounds considered as pollutants of high priority due to their carcinogenic potential. PAH can appear in water, soil or in the atmosphere as adsorbed on particulate material or in gas phase. An increased number of studies on atmospheric PAH in urban areas have been published in the last decade, especially in the last years. Anthropogenic sources are frequently mentioned to be responsible for the increased concentration of PAHs in the atmosphere of urban areas, which at the same time seems to depend on meteorological parameters. This research is focused on compiling information on PAH levels in Latin America and their relationship with typical meteorological variables from seasonal and tropical countries. Brazil is the country with the most number of bibliographies about this topic, followed by Argentina, Chile and Mexico. Scarce information was found for Colombia and Venezuela and none for the rest of Latin American countries. The majority of studies checked have evaluated the climatological parameters in relationship with the PAH concentration and their distribution, finding that it affects meaningfully their levels. The monitor campaigns in Brazil have been developed mainly in the southern cities, where PAHs are strongly influenced by the seasons and their proximity to the South Pole. Tropical countries such as Venezuela and Colombia showed moderate variation of PAH concentration through months. The main influential parameters are precipitation and direction/speed winds.     

吉林市哈达湾工业区大气气溶胶中萘和联苯的污染特征

大气气溶胶中的多环芳烃是对人体健康危害最大的环境污染物之一.对2003年至2004年在吉林市哈达湾和江南公园采集的31个大气气溶胶样品,采用超声波萃取法提取其中的多环芳烃,对其进行浓缩和层析,用高效液相色谱法对其中的萘和联苯进行定量分析.得到哈达湾采样点萘和联苯的浓度均高于江南公园采样点萘和联苯的浓度.     

Preparation and nanotribological behavior of PAH/graphite oxide molecular deposition film

Asanewtechniquetoprepareultrathinfilms,moleculardeposition(MD)methodcanbeusedtoassemblemultilayersofnanometerthicknessbywayofintermolecularelectrostaticforces[1,2].IthasbeenfoundthatMDfilmisabletodecreasetheadhesiveforceonasurfaceandhencetohealthefrictionsurfaceanddecreasethefrictionforce[3—7].However,MDfilmhaspoorantiwearbehavior,owingtotheweakintermo-lecularforcesincludingtheelectrostaticforce.Therefore,itisimperativetoseekforwaystoincreasethebondingstrengthoftheMDfilmsintermsoftheirengi…     

Revealing the Origin of Polycyclic Aromatic Hydrocarbons in an Urban Snowpack

Polyciclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban atmosphere. Several PAHs are known carcinogens or are the precursors to carcinogenic daughter compounds. Understanding the contributions of various PAH emission sources is critical to appropriately managing PAH levels in the environment. The sources of PAHs to urban snowpack in Shelekhov city, Eastern Siberia, characterized by extremely high levels of PAH accumulation in snow were determined by using end-member mixing approach. The best potential to distinguish PAH emission sources is exhibited by ratios of PAH pairs of the principal mass 228, 252, and 276. The ratios of PAH pairs were used as tracers of end-member PAH sources. The contributions of sources were calculated using systems of linear equations. The results obtained using ratios of PAH pairs were compared with those obtained using molecular diagnostic ratios. It was shown that the results obtained using diagnostic ratios as tracers are less reliable than the results obtained using the ratios of the sums of PAHs.     

Controlled accommodation of metal nanostructures within the matrices of polymer architectures through solution-based synthetic strategies

Controlled accommodation of metal nanostructures (MNSs) into the matrix of a well-defined polymer architecture offers an effective approach to achieve hierarchically structured nanocomposites with tunable synergistic properties to broaden application potentials in the emerging fields of energy, environmental science, and medicine. This review focuses on the recently developed zero-dimensional and one-dimensional MNSs@polymer hybrid nanostructures obtained by solution-based synthetic strategies. Progress in the controlled synthesis of those hybrid nanostructures in terms of the number (e.g., monomer, dimer and trimer), organization manner (e.g., linear alignment or confined assembly in certain domains), and spatial arrangement (e.g., in the core and shell) of the MNSs within the distinct polymer matrices are detailed. The synergistic properties and potential applications of those MNSs@polymer hybrids associated with their compositions and morphologies are also reviewed.     

Bioremediation of polycyclic aromatic hydrocarbons (PAH) in an aged coal-tar-contaminated soil using different in-vessel composting approaches

The biodegradation of 16 USEPA-listed PAHs (SigmaPAHs) during simulated in-vessel composting-bioremediation of an aged coal-tar-contaminated soil amended with fresh green waste compost (FGWC) collected from two landfill sites in the United Kingdom (UK) were studied over 56 days. The experimental design compared three constant temperature profiles (TC=38, 55 and 70 degrees C) with one variable temperature profile including treatment at 70 degrees C to comply with regulatory requirements (TP1). The highest disappearance of SigmaPAHs was observed in the soil amended with FGWC (53.2% and 48.1% SigmaPAHs disappearance in soil amended with FGWC-Site 1 and FGWC-Site 2, respectively) containing lower initial organic mater (TOM) (Initial TOM(FGWC-Site 1)=25.6+/-0.6%PAHs occurred when the same coal-tar soil was amended with fresh green waste (56.0% SigmaPAHs disappearance in soil amended with fresh green waste) instead of FGWC. Using a constant TC1=38 degrees C resulted in a higher disappearance of SigmaPAHs when compared to other temperature treatments. However, using a variable temperature profile TP1 during in-vessel composting of a soil amended with fresh green waste is required to promote contaminant degradation and pathogen control.