Emissions of air pollutants from indoor charcoal barbecue.

Ten types of commercial charcoal commonly used in Taiwan were investigated to study the potential health effects of air pollutants generated during charcoal combustion in barbecue restaurants. The charcoal samples were combusted in a tubular high-temperature furnace to simulate the high-temperature charcoal combustion in barbecue restaurants. The results indicated that traditional charcoal has higher heating value than green synthetic charcoal. The amount of PM10 and PM2.5 emitted during the smoldering stage increased when the burning temperature was raised. The EF for CO and CO2 fell within the range of 68-300 and 644-1225 g/kg, respectively. Among the charcoals, the lowest EF for PM2.5 and PM10 were found in Binchotan (B1). Sawdust briquette charcoal (I1S) emitted the smallest amount of carbonyl compounds. Charcoal briquettes (C2S) emitted the largest amount of air pollutants during burning, with the EF for HC, PM2.5, PM10, formaldehyde, and acetaldehyde being the highest among the charcoals studied. The emission of PM2.5, PM10, formaldehyde, and acetaldehyde were 5-10 times those of the second highest charcoal. The results suggest that the adverse effects of the large amounts of air pollutants generated during indoor charcoal combustion on health and indoor air quality must not be ignored.

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer.

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180-320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.

Aerosol penetration properties of an electret filter with submicron aerosols with various operating factors.

This study was undertaken to determine the effects of using an electret filter on aerosol penetration. Various factors, including particle size (0.05 to 0.5 micro m), aerosol charge state (neutral and single charge), face velocity (0.1, 0.3, 0.5 and 1.0 m/s), and relative humidity (RH 30% and RH 70%), were examined to assess their effects on aerosol collection characteristics. The results presented here demonstrate that the electric fields of the electret and discharged filter were -1.53 x 104 and -1.3 x 102 (V/m). The penetration through the electret filter with singly charged aerosol and neutral aerosol ranged from 0.4% to 13% and 14% to 29%, respectively. According to these results, the coulombic capture force was dominant for the smaller aerosol and the dielectrophoretic capture mechanism was considered important for the larger aerosol. The level of penetration through the electret filter increased with increasing face velocity and relative humidity. The temperature did not affect the penetration through the electret. Furthermore, from the regression analysis conducted during the operating conditions of this work, the aerosol charge was shown to exert the greatest influence on aerosol penetration.

Removal of vaporous naphthalene using polyoxyethylenated nonionic surfactants.

Previous research has demonstrated that an anionic surfactant can increase the solubility of the vapor phases of both naphthalene and sulfur dioxide in water. This study examines the feasibility of removing polycyclic aromatic hydrocarbons (PAHs) during gas absorption by adding the polyoxyethylenated nonionic surfactants tetraethylene glycol monodecyl ether (C10E4), octaethylene glycol monodecyl ether (C10E8), and octaethylene glycol monotetradecyl ether (C14E8), to water. The apparent solubility and absorption rates of naphthalene in surfactant solution were slightly higher than in pure water at a concentration lower than the critical micelle concentration (CMC). However, the apparent equilibrium naphthalene solubility increased linearly in proportion to the concentrations of nonionic surfactants because of the solubilization effect of micelles at concentrations above the CMC. The solubilization effect exceeded that of the reduced mass transfer coefficient, increasing the rate of absorption of vaporous naphthalene. For the four surfactants, the capacity to solubilize naphthalene was in the order C10E4 > C14E8 > C10E8 > sodium dodecyl sulfate (SDS) and was related to the hydrophile-lipophile balance values of the surfactants. The enrichment factors, which can express the degree of naphthalene solubility in solution, were 6.09-14.2 at a surfactant concentration of 0.01 M for the three polyoxyethylenated nonionic surfactants. Empirical findings confirm that adding nonionic surfactants increases the absorption efficiency of hydrophobic organic compounds (HOCs) using spray or packed tower.