Evaluation of sink effects on VOCs from a latex paint

The sink strength of two common indoor materials, a carpet and a gypsum board, was evaluated by environmental chamber tests with four volatile organic compounds (VOCs): propylene glycol, ethylene glycol, 2-(2-butoxyethoxy)ethanol (BEE), and Texanol. These oxygenated compounds represent the major VOCs emitted from a latex paint. Each chamber test included two phases. Phase 1 was the dosing/sorption period during which sink materials (pieces of carpet and gypsum board samples) were exposed to the four VOCs. The sink strength of each material tested was characterized by the amount of the VOCs adsorbed or absorbed. Phase 2 was the purging/desorption period during which the chambers with the dosed sink materials were flushed with purified air. The reemission rates of the adsorbed VOCs from the sinks were reflected by the amount of the VOCs being flushed. Phase 1 results indicated that the sink strength for the four target compounds is more than 1 order of magnitude higher than that for other VOCs previously tested by the U.S. Environmental Protection Agency (EPA). The high sink strength reflected the unusually high sorption capacity of common indoor materials for the four VOCs. Phase 2 results showed that reemission was an extremely slow process. If all the VOCs adsorbed were reemittable, it would take more than a year to completely flush out the VOCs from the sink materials tested. The long reemission process can result in chronic and low-level exposure to the VOCs after painting interior walls and surfaces.     

Biological Removal of Gaseous VOCs from Automotive Painting Operations

Among the pollutants that automotive plants produce, volatile organic compound (VOC) emissions due to paint solvents from painting operations are the largest in quantity. The current control process, based on vapor-phase adsorption followed by thermal oxidation, is costly to install and operate. At Ford, a cost-effective method of removing VOCs has been investigated that involves converting an existing spraybooth scrubber system to a biological reactor. This paper reports the results of a pilot-scale investigation in which two activated-sludge bioreactors, one with and the other without powdered activated carbon (PAC), were operated in parallel for 16 months. The primary findings include (1) The biological VOC removal process was technically feasible, and a scrubber system at a typical assembly plant is sufficiently large to handle the solvent loading used under normal vehicle-production conditions; (2) as compared to the adsorption∕thermal oxidation process, the biological process was found to be comparable in VOC removal efficiency, an order of magnitude more cost-effective in capital cost, and a factor of two more cost-effective in operating and maintenance cost; and (3) the bioreactors effectively captured and degraded hydrophilic paint solvents (methyl ethyl ketone, n-butanol, and butyl cellosolve) that were fed via the vapor phase. Toluene, a hydrophobic solvent, was also well-captured and degraded (74 to 91% without PAC and 86 to 93% with PAC).     

Programmed energy dispersive X-ray analysis of top coats of automotive paint

Elemental, qualitative, and semiquantitative analyses of 1974 U.S. automotive paints by a Finnigan Model 900F Energy Dispersive X-ray (EDX) Spectrometer are examined. This EDX analytical system incorporates a minicomputer to receive, store, and present data. The paint samples were received from the National Bureau of Standards (NBS) Law Enforcement Standards Laboratory as a collection representative of the top coats used on all U.S. manufactured automobiles in 1974. Aspects considered include EDX system stability, homogeneity of similarly catalogued samples from different NBS collections, categorization of paints by predominant constituents, and comparison of data on paint standards that were similar. Automated analysis represents an important application of forensic science to the characterization of paint samples and provides for the nondestructive analysis of a variety of materials in a large range of sample sizes and concentrations.     

基于文献计量解析VOCs催化氧化的发展趋势

以VOCs的催化氧化为主题,利用Web of Science数据库对4654篇论文进行了数据处理,并通过文献计量学的方法分析了该主题的发展趋势与研究现状。结果表明,近25年期间,VOCs催化氧化相关课题的研究底蕴丰富,发展前景良好,年度发文数量呈指数型增长趋势。中国是世界上发表VOCs催化氧化为主题的论文最多的国家,占研究总量的34%;研究最深的机构和期刊分别是中国科学院大学（6.66%）和Applied Catalysis B-Environmental（11.68%）;Chemistry和Engineering是最受欢迎的科目。此外,对近年来的研究热词分析表明,应用于VOCs催化氧化的催化剂中,最热门的元素是Mn,实验中最常见的VOCs类底物是甲苯。总结了常见的催化剂物质和VOCs底物,这反映了目前的主要研究方向,也为今后的研究提供了指导。      

Gas-Liquid Mass Transfer along Small Sewer Reaches

Municipal and industrial sewers may be localized sources of volatile organic compound (VOC) emissions to the ambient atmosphere. Previous studies of VOC emissions from sewers have focused on sewers with large diameters that are often characterized as having mild channel slopes and as conveying relatively large wastewater flow rates. The study described in this paper was completed to better understand VOC emissions from sewer reaches with small diameters, steep channel slopes, and relatively low wastewater flow rates (e.g., as might be typical for building laterals, street sewers, and on-site industrial sewers). Mathematical models were developed to investigate the nature of mass transfer kinetics and equilibrium conditions in such sewers. A series of 20 experiments were then completed to determine liquid-phase and gas-phase mass transfer coefficients for a range of sewer operating conditions and chemical properties. Experiments were completed in an experimental sewer reach (60 m length, 0.2 m diameter) using five volatile chemicals (acetone, ethyl acetate, toluene, ethylbenzene, and cyclohexane, listed in order of increasing Henry's law constants). Experimental stripping efficiencies were as high as 47% for cyclohexane and as low as 0.3% for acetone. Experimental and mathematical results indicate that VOCs with low Henry's law constants (e.g., acetone) can reach equilibrium conditions rapidly in sewers. However, emissions of VOCs with high Henry's law constants (e.g., cyclohexane) are kinetically limited, allowing for the sewer to be treated as an “open” system. The findings described herein suggest that a large fraction of VOCs with high Henry's law constants may be emitted to the ambient atmosphere in the near vicinity to the point of discharge.     

Treatment of Paint Spray Booth Off-Gases in a Fungal Biofilter

Biological processes, most notably biofilters and biotrickling filters, are increasingly used to remove and biodegrade a wide variety of volatile organic compounds (VOCs) present in gas streams emitted from industrial operations. In the research described herein, a laboratory-scale biofilter was operated for a period of more than 180 days to treat a waste gas comprised of a four-component VOC mixture representative of solvents present in off-gases emitted by painting operations. The biofilter, packed with a cubed polyurethane foam media and initially inoculated with a pure culture of the fungus Cladosporium sphaerospermum, was maintained under acidic conditions throughout the duration of the experiments. The system was supplied with a mixture of n-butyl acetate, methyl ethyl ketone, methyl propyl ketone, and toluene with influent concentrations of 124, 50.5, 174, and 44.6 mg?m?3, respectively. The biofilter’s empty bed residence time (EBRT) was varied from 2.0 min to 15 s. When the influent gas stream was properly humidified, the system exhibited stable long-term performance with an average total VOC removal greater than 98% even with an EBRT as low as 15 s. Under the loading condition tested, this corresponds to an average elimination capacity of 92 g?m?3?h?1. VOC concentration profiles measured along the height of the biofilter revealed a distinct VOC degradation pattern that was observed under all loading conditions tested. Although the column was initially inoculated with only Cladosporium sphaerospermum, several additional species of fungi tentatively identified as Penicillium brevicompactum, Exophiala jenselmei, Fusarium oxysporum, Fusarium nygamai, Talaromyces flavus, and Fonsecaea pedrosi were found growing attached to the packing medium by the end of experiment. Results demonstrate that fungal biofilters can consistently maintain high removal efficiency for paint VOC mixtures over extended periods of operation. The results also indicate that it would be difficult and likely unnecessary to maintain specific species in full-scale fungal biofilters treating paint spray booth emissions.     

Lanthanum-exchanged zeolite and clay as anticorrosive pigments for galvanized steel

A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc phosphate, has, at present, raised some environmental concern because phosphate causes the eutrophication of water courses and zinc itself is toxic. The aim of this re-search was to study the anticorrosive performance of a mixture consisting of zinc phosphate, modified zeolite and clay （bentonite） in order to diminish phosphate content in paints. The zeolite and the clay were exchanged with La（III） ions, as inorganic green inhibitor. In the first step, the anticorrosion protection by La（III） ions in solution was assessed by electrochemical tests. In the second step, an epoxy-polyamide paint formulated with the pigment mixture applied on galvanized panels was studied by salt spray test and electro-chemical noise measurements （ENM）. The results showed that it was possible to replace part of the zinc phosphate content in the paint with the exchanged zeolite and the clay.     

Synthesis and characterization of aluminum and Al/REE pillared clays and supported palladium catalysts for benzene oxidation

Volatile organic compounds (VOCs) are considered as a major pollutant in indoor and outdoor air.More stringent environmental regulations have been implemented in order to reduce the VOC emissions.One of the techniques available for destructive removal of VOCs is catalytic oxidation.In the present work,Al/Rare Earths (REE: Y,Ce,La,Pr and Nd) pillared clays (PILCs) were used to support 0.2 wt.% of palladium for the complete oxidation of low concentration of benzene.The supports and catalysts were characterize...     

Determination of motor vehicle profiles for non-methane organic compounds in the Mexico City metropolitan area

Non-methane organic compound (NMOC) profiles for on-road motor vehicle emissions were measured in a down-town tunnel and parking garages in Mexico City during 1996. Hydrocarbon samples from the tunnel and ambient air samples (C2-C12) were collected using stainless steel canisters, and carbonyl compounds were collected using 2,4-dinitrophenylhydrazine (DNPH) impregnated cartridges. Canister samples were analyzed by gas chromatography/flame ionization detection (GC/FID) to ascertain detailed hydrocarbon composition. DNPH samples were analyzed by high performance liquid chromatography (HPLC). NMOC source profiles were quantified for evaporative emissions from refueling, cold start, and hot soak, and on-road operating conditions. The ultimate purpose will be to determine the apportionment of ambient NMOC concentrations using the Chemical Mass Balance (CMB) model. The tunnel profile contained 42.3 ppbC% of alkanes, 20.6 ppbC% of unsaturated compounds, and 22.4 ppbC% of aromatics. The most abundant species were acetylene with 7.22 ppbC%, followed by ipentane with 5.69 ppbC%, and toluene with 5.42 ppbC%. These results were compared with those from studies in the United States. The cold start profile was found to be similar to the tunnel profile, although there were differences in the content of acetylene, isopentane, and oxygenates. The abundance of saturated NMOC in the hot soak profile was similar to gasoline head space profiles; it was also much larger than saturated NMOC in the roadway profile.     

镁合金微弧氧化-涂装体系的研究

提出了一种镁合金/微弧氧化膜/有机涂层的镁合金防护体系.在以硅酸钠为主的复合溶液中,利用双向对称脉冲电压在阴、阳极镁合金表面同时微弧电沉积陶瓷膜.利用盐雾实验比较了以镁合金微弧氧化膜为基底并涂覆环氧底漆和聚胺脂丙烯酸面漆的试样与镁合金/微弧氧化膜/有机硅、镁合金/微弧氧化膜/溶胶凝胶涂装试样的耐蚀性,并利用盐雾实验与交流阻抗谱相结合跟踪对比分析了镁合金/有机涂层、镁合金/铬酸盐转化膜/有机涂层、镁合金/微弧氧化膜/有机涂层的屏蔽性能.结果表明:采用溶胶凝胶、有机硅和有机涂层对微弧氧化膜进行涂装的方法均可进一步提高镁合金的耐蚀性,其中镁合金/微弧氧化膜/有机涂层试样可承受480h以上的中性盐雾实验,且其介质屏蔽性能优于镁合金/有机涂层和传统的镁合金/铬酸盐转化膜/有机涂层防护体系.     

Effect of Moisture on the Adsorption of Volatile Organic Compounds by Zeolite 13×

The adsorption of volatile methanol, acetone, and benzene onto zeolite 13× was studied in the presence of water vapor. Breakthrough curves for these volatile organic compounds (VOCs) were measured by using a gas-phase Fourier transformation infrared (FT-IR) spectrometer instead of a gas chromatograph (GC) because a gas-phase FT-IR spectrometer provides a more rapid response to the change of gas concentration than that of GC. To observe the influences of humidity (i.e., water vapor) on the performance of zeolite 13× during the VOC adsorption, the adsorption experiments were carried out at three different initial concentrations and two humidity conditions for each VOC. The results showed a significant influence of increased humidity on the breakthrough time, the shapes of breakthrough curves, and the uptake of VOCs. For the case of the benzene and water vapor coadsorption system, the presence of the moisture caused a greater decrease in the VOC uptake as well as the breakthrough time than for the other VOC–water coadsorption systems. A modified Freundlich-type isotherm was introduced in this study to describe the decrease in the uptake of VOCs in the presence of the moisture. This modified empirical equation provided a good fit to experimental results, with an average error of 8%.     

Indoor air quality impacts of ventilation ducts: ozone removal and emissions of volatile organic compounds

The concentrations of contaminants in the supply air of mechanically ventilated buildings may be altered by pollutant emissions from and interactions with duct materials. We measured the emission rate of volatile organic compounds (VOCs) and aldehydes from materials typically found in ventilation ducts. The emission rate of VOCs per exposed surface area of materials was found to be low for some duct liners, but high for duct sealing caulk and a neoprene gasket. For a typical duct, the contribution to VOC concentrations is predicted to be only a few percent of common indoor levels. We exposed selected materials to approximately 100-ppb ozone and measured VOC emissions. Exposure to ozone increased the emission rates of aldehydes from a duct liner, duct sealing caulk, and neoprene gasket. The emission of aldehydes from these materials could increase indoor air concentrations by amounts that are as much as 20% of odor thresholds. We also measured the rate of ozone uptake on duct liners and galvanized sheet metal to predict how much ozone might be removed by a typical duct in ventilation systems. For exposure to a constant ozone mol fraction of 37 ppb, a lined duct would initially remove approximately 9% of the ozone, but over a period of 10 days of ozone removal efficiency would diminish to less than 4%. In an unlined duct, in which only galvanized sheet metal is exposed to the air-stream, the removal efficiency would be much lower, approximately 0.02%. Therefore, ducts in ventilation systems are unlikely to be a major sink for ozone.     

Cultured astrocytes express proteins involved in vesicular glutamate release

The objective of this study is to analyze volatile organic compound (VOC) concentrations in Taiwan's drinking water supply. Focusing on Taiwan's three major metropolitan areas--Taipei, Taichung and Kaohsiung (in the north, middle and south, respectively)--171 samples were taken from tap water and 68 from boiled water. Tests showed VOC concentrations were highest in Kaohsiung. This is due to different water sources and methods of treatment. Except for bromoform, trihalomethane (THM) concentrations were highest. Detection rates of toluene and 1,2-dichloroethane were slightly higher than other VOC compounds. VOC concentrations decreased significantly after water was boiled. THMs had a removal rate from 61% to 82%. The authors conclude that the three metropolitan areas contain significantly different levels of VOCs and that boiling can significantly reduce the presence of VOCs. Other sources of pollution that contaminate drinking water such as industrial plants and gas stations must be further investigated.     

Load Dampening System for Vapor Phase Bioreactors

Vapor phase bioreactors are receiving increasing attention as a cost-effective treatment method for air contaminated with volatile organic compounds (VOCs). In this study, a novel absorption and humidification system was evaluated for its ability to dampen transient VOC loads, and to reduce their detrimental effects on a downstream bioreactor. A model based on the mass transfer characteristics of two target compounds (acetone and toluene) was developed and takes into account a closed water recirculation loop that minimizes fugitive emissions and simultaneously humidifies the inlet gas stream. When water is used as the scrubbing liquid, model and experimental results indicate that the system effectively dampens hydrophilic compounds and segregates them from the hydrophobic compounds in the waste gas stream. The response of a vapor phase bioreactor to the pretreated stream has also been assessed, and results indicate that the load dampening system works effectively for hydrophilic, but not hydrophobic, VOCs. However, when an organic cosolvent is used in conjunction with water, hydrophobic VOCs can also be dampened efficiently.     

高温远红外涂料在攀钢加热炉上的应用

介绍发攀钢轨梁厂加热炉应用高温远红外涂料事对加热炉的能耗，炉温，炉衬寿命，钢坯烧损及钢坯待热时间的影响。试验结果表明，炉衬内表面喷涂涂料事，加热炉的能耗，钢坯烧损，钢坯待热时间均闰少，炉膛热效率提高，炉衬剥落明显减少，综合经济效益明显。     

Influence of Surface Condition on the Inspection of Steel Bridge Elements Using the Time-of-Flight Diffraction Method

Prior studies on the time-of-flight diffraction (TOFD) method have focused primarily on ground smooth, clean surfaces of steel. In practice, however, the surface of an existing bridge element will be covered with rust or have several layers of paint. The main objective of this study was to evaluate the influence of the surface condition of steel elements (i.e., painted or rusted) on the ability of the method to accurately detect and size flaws. These objectives were met by performing a number of tests on plates with saw cuts or implanted fatigue cracks with different surface conditions. These included ground smooth and polished, rusted, and painted surfaces. The data show that rusted surfaces will reduce the amplitude of the ultrasonic signals, but they will not impair the ability of the TOFD method to detect and accurately size flaws. A painted surface will also cause a reduction in signal amplitude. More important, however, is the appearance of additional wave signals that could be interpreted as false indications. While these additional signals do not obscure the presence of actual flaws or affect the accuracy of the TOFD method to size the flaws, they make flaw detection more difficult. Based on the results of this study, recommendations for field inspection on rusted or painted surfaces using the TOFD method are provided.     

Aircraft conspicuity and flight attitude information provided by exterior paint patterns.

Experiments were conducted to determine the relative conspicuity of aircraft exterior paint patterns, and to investigate whether such paint patterns aided pilots in determining the attitude of the aircraft. The conspicuity studies, using paired comparisons of model airplanes, gave evidence that: (a) amount of red-orange fluorescent paint coverage is positively correlated with conspicuity; (b) high brightness paints should be placed on the upper surfaces of the aircraft and low brightness paints on the lower portions; (c) maximizing brightness contrasts between different parts of the aircraft surfaces does not enhance conspicuity; (d) flight attitudes, backgrounds, lighting conditions, and differences in Ss did not affect conspicuity significantly. The attitude studies in which pilots matched the model airplanes in some 1 of 15 attitudes, with 1 of 15 models mounted on a small display, indicated that the paint patterns used did not aid the pilots in making judgments of aircraft attitude. Differences in backgrounds and lighting conditions did not greatly affect Ss' ability to determine attitude. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk in cleaning: chemical and physical exposure

Cleaning is a large enterprise involving a large fraction of the workforce worldwide. A broad spectrum of cleaning agents has been developed to facilitate dust and dirt removal, for disinfection and surface maintenance. The cleaning agents are used in large quantities throughout the world. Although a complex pattern of exposure to cleaning agents and resulting health problems, such as allergies and asthma, are reported among cleaners, only a few surveys of this type of product have been performed. This paper gives a broad introduction to cleaning agents and the impact of cleaning on cleaners, occupants of indoor environments, and the quality of cleaning. Cleaning agents are usually grouped into different product categories according to their technical functions and the purpose of their use (e.g. disinfectants and surface care products). The paper also indicates the adverse health and comfort effects associated with the use of these agents in connection with the cleaning process. The paper identifies disinfectants as the most hazardous group of cleaning agents. Cleaning agents contain evaporative and non-evaporative substances. The major toxicologically significant constituents of the former are volatile organic compounds (VOCs), defined as substances with boiling points in the range of 0 degree C to about 400 degrees C. Although laboratory emission testing has shown many VOCs with quite different time-concentration profiles, few field studies have been carried out measuring the exposure of cleaners. However, both field studies and emission testing indicate that the use of cleaning agents results in a temporal increase in the overall VOC level. This increase may occur during the cleaning process and thus it can enhance the probability of increased short-term exposure of the cleaners. However, the increased levels can also be present after the cleaning and result in an overall increased VOC level that can possibly affect the indoor air quality (IAQ) perceived by occupants. The variety and duration of the emissions depend inter alia on the use of fragrances and high boiling VOCs. Some building materials appear to increase their VOC emission through wet cleaning and thus may affect the IAQ. Particles and dirt contain a great variety of both volatile and non-volatile substances, including allergens. While the volatile fraction can consist of more than 200 different VOCs including formaldehyde, the non-volatile fraction can contain considerable amounts (> 0.5%) of fatty acid salts and tensides (e.g. linear alkyl benzene sulphonates). The level of these substances can be high immediately after the cleaning process, but few studies have been conducted concerning this problem. The substances partly originate from the use of cleaning agents. Both types are suspected to be airway irritants. Cleaning activities generate dust, mostly by resuspension, but other occupant activities may also resuspend dust over longer periods of time. Personal sampling of VOCs and airborne dust gives higher results than stationary sampling. International bodies have proposed air sampling strategies. A variety of field sampling techniques for VOC and surface particle sampling is listed.     

二氧化钛基材料光催化降解VOCs的研究进展

挥发性有机污染物(VOCs)大量排放导致的人体健康和环境问题已引起广泛关注,如何高效环保地去除VOCs一直是催化化工行业领域的热点和难题之一.光催化氧化技术(PCO)被认为是有效的环境污染物治理方法之一.TiO₂作为研究时间最长的光催化剂,具有成本效益高、稳定性好和光催化降解能力强等优点.然而,无法利用可见光和光激发电荷载流子分离效率低等瓶颈问题始终制约着其进一步发展.通过改性来克服TiO₂固有限制和提高TiO₂光催化氧化降解VOCs能力势在必行,立足于TiO₂光催化去除VOCs的基本原理,面向影响光催化反应的关键因素,从掺杂、半导体复合、缺陷工程、晶面工程、载体吸附和形貌调控等几个方面出发对近年TiO₂基材料设计及其在光催化降解VOCs领域应用的研究进行了系统的归纳和总结,并对如何进一步改进基于TiO₂的光催化氧化VOCs技术提出展望.     

Capture of Organic Vapors Using Adsorption and Electrothermal Regeneration

Activated-carbon-fiber cloth (ACFC) is an alternative adsorbent to granular activated carbon (GAC) for removing and recovering organic vapors from gas streams. Electrothermal desorption (ED) of ACFC provides rapid regeneration while requiring less energy compared to traditional regeneration techniques used with GAC. This paper provides proof-of-concept results from a bench-scale ACFC adsorption system. The automated system captured 1,000 ppmv of hazardous air pollutants/volatile organic compounds (HAPs/VOCs) from air streams and demonstrated the use of ED, using ac voltage, to recover the HAP/VOC as a pure liquid. The desorbed HAP/VOC condensed onto the inner walls of the adsorber and was collected at the bottom of the vessel, without the use of ancillary cooling. Seventy percent of the HAP/VOC was collected per cycle as condensate, with the balance being retained in the regenerated adsorber or recycled to the second adsorber. ED with in-vessel condensation results in minimal N2 consumption and short regeneration cycle times allowing the process to be cost competitive with conventional GAC-based adsorption processes. This technology extends the application of carbon adsorption systems to situations that were previously economically and physically impractical.