Characterization of emissions of volatile organic compounds from interior alkyd paint

Alkyd paint continues to be used indoors for application to wood trim, cabinet surfaces, and some kitchen and bathroom walls. Alkyd paint may represent a significant source of volatile organic compounds (VOCs) indoors because of the frequency of use and amount of surface painted. The U.S. Environmental Protection Agency (EPA) is conducting research to characterize VOC emissions from paint and to develop source emission models that can be used for exposure assessment and risk management. The technical approach for this research involves both analysis of the liquid paint to identify and quantify the VOC contents and dynamic small chamber emissions tests to characterize the VOC emissions after application. The predominant constituents of the primer and two alkyd paints selected for testing were straight-chain alkanes (C9-C12); C8-C9 aromatics were minor constituents. Branched chain alkanes were the predominant VOCs in a third paint. A series of tests were performed to evaluate factors that may affect emissions following application of the coatings. The type of substrate (glass, wallboard, or pine board) did not have a substantial impact on the emissions with respect to peak concentrations, the emissions profile, or the amount of VOC mass emitted from the paint. Peak concentrations of total volatile organic compounds (TVOCs) as high as 10,000 mg/m3 were measured during small chamber emissions tests at 0.5 air exchanges per hour (ACH). Over 90% of the VOCs were emitted from the primer and paints during the first 10 hr following application. Emissions were similar from paint applied to bare pine board, a primed board, or a board previously painted with the same paint. The impact of other variable, including film thickness, air velocity at the surface, and air-exchange rate (AER) were consistent with theoretical predictions for gas-phase, mass transfer-controlled emissions. In addition to the alkanes and aromatics, aldehydes were detected in the emissions during paint drying. Hexanal, the predominant aldehyde in the emissions, was not detected in the liquid paint and was apparently an oxidation product formed during drying. This paper summarizes the results of the product analyses and a series of small chamber emissions tests. It also describes the use of a mass balance approach to evaluate the impact of test variables and to assess the quality of the emissions data.     

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.     

Emissions from building products and investigation of their toxicity with the bioluminescence inhibition test

The investigation of building products in test chambers contains so far only analytical and sensory measurements. In this paper, first experiments for the direct testing of the acute toxicity of building product emissions with the bioluminescence inhibition test are presented. The test specimen was a solvent-free dispersion paste for gluing carpets. Two tests with different air change rates were performed in a 1 m3 stainless steel test chamber. The emissions were concentrated at uniform timesteps in impinger-bottles and measured with the bioluminescence inhibition test. At the same time the concentrations of the emissions in the test chamber were measured both with charcoal adsorbent tubes (carbon disulphide desorption) and with tenax tubes (thermal desorption). The results of the bioluminescence inhibition test show, that the decrease of the toxicity over a period of 28 days is far lower at a low air change rate than at a higher air change rate. We also found, that from the multitude of the emitted substances the toxicity for the luminescence bacteria was only caused by Ethanol-[2-(2-butoxyethoxy)]-acetate.     

Effect of a chlorhexidine/thymol-containing varnish on prostaglandin E2 levels in gingival crevicular fluid

The aim was to study the effect of a chlorhexidine/thymol-containing varnish (Cervitec) on the levels of prostaglandin E2 (PGE2) in gingival crevicular fluid (GCF). The material consisted of 25 adolescents and young adults with fixed orthodontic appliances exhibiting gingival inflammation. Four buccal sites, adjacent to bands and brackets, were selected on each patient and randomly treated with either a varnish containing chlorhexidine diacetate (1% w/w) and thymol (1% w/w) or a placebo varnish without active ingredients. After baseline registration, the varnishes were applied twice within 3 d. Follow-up examinations were performed after 3, 8 and 30 d. The gingival inflammation was assessed by bleeding on probing, volume of GCF with a Periotron 8000 and PGE2 level in GCF by using a radioimmuno assay. Compared with baseline, a statistically significant reduction in the volume of GCF was recorded at the chlorhexidine/thymol treated sites in contrast to the placebo. The mean PGE2 levels were significantly reduced after the test varnish treatment compared with baseline and differed significantly from placebo after 8 d. The findings suggest that treatments with the antibacterial varnish result in reduced gingival inflammation and may thus be beneficial for patients with fixed orthodontic appliances.     

Estimation of Mass Transport Parameters of Organic Compounds through High Density Polyethylene Geomembranes Using a Modifield Double-Compartment Apparatus

A modified double-compartment apparatus (MDCA) is used to estimate mass transport parameters of organic compounds through high density polyethylene (HDPE) geomembranes and to investigate the effects of aging and external tension of HDPE geomembranes on the mass transport of organic compounds. A developed one-dimensional partition–diffusion mass transport model successfully explains the mass transport of the organic compounds through the HDPE geomembranes in a dilute aqueous solution–geomembrane system. Similar to batch immersion tests, the HDPE–water partition coefficient (KHDPE–W) values of organic compounds are found to have close relationships with the octanol–water partition coefficient and the aqueous solubility; furthermore, the diffusion coefficient (D) values decrease with the increase of their molecular diameter. For HDPE geomembranes served in the landfill liner for 5 years and stretched by 8% of their initial length, KHDPE–W values for organic compounds increase by 5–58%, D values for organic compounds increase by 10–86%, and breakthrough times are faster, indicating more amounts of organic compounds may break through the HDPE geomembrane in fields than expected. The mass transport parameters from MDCA tests could be used with those from batch immersion tests interchangeably after mass loss and immobilization of organic compounds in MDCA tests are considered.     

Sick building syndrome and HVAC system: MVOC from air filters

Growth and emissions of volatile metabolites of microorganisms on air filters are suspected to contribute to health complaints in ventilated rooms. To prove the microbiological production of volatile organic compounds (MVOC), concentrations of aldehydes and ketones were determined in two large HVAC systems. The in situ derivated aldehydes and ketones (as 2,4-dinitrophenyl-hydrazones) were analysed by HPLC and UV detection. The detection limit of each compound was 1 ppb (margin of error < 10%). Field measurements were carried out before and after the prefilters and the main filters, respectively, to investigate whether aldehydes and ketones increase in concentration after filters of HVAC systems. First results show that the compounds formaldehyde, acetaldehyde and acetone could be detected before and after the filters. The concentrations of these VOC after the filters were significantly increased--as a mean over twenty measurements--, especially as far as filters made of glass fibre are concerned. However the found concentrations were low and mostly comparable to outdoor findings. In simultaneous laboratory experiments pieces of used filter material of one HVAC system and unused filter pieces (for blank values) were examined in small incubation chambers to investigate the possible production of MVOC. For the incubation a temperature of 20 degrees C and a relative humidity of 95% was chosen. In these experiments an almost identical spectrum of compounds (formaldehyde and acetone) was found as in the field measurements. The concentrations of these compounds were higher in the chambers with the used filter pieces. The concentration of acetone ranged up to almost 12 mg/m3.--As our field experiments correspond with our laboratory experiments, we assume that the microbial production of volatile organic compounds in HVAC systems under operating conditions is possible.     

Study on Anticorrosive Cerium Conversion Coating of Cf/6061Al Composite Surface

The optimum chemical passivation process of the rare earth metal (REM) conversion coating on the Cf/6061Al composite surface was introduced in this paper and its polarization curves properties were investigated. Ridge-like coatings were found by scanning electro microscope (SEM) observations, and the Al matrix and carbon fibre reinforcement were both coated with Ce conversion coatings, with some minor cracks. The energy dispersive spectroscopy (EDS) plane scan analysis indicates that the major elements in the coating are Ce, O, Si, Al and the Ce content reaches 47.48%(mass fraction). The Ce conversion coatings increase the corrosion resisting properties of Cf/6061Al composite, with a higher free corrosion potential (Ecorr) and a lower free corrosion current density (icorr) for the coated composite than those of the bare composite. And the Boehmite-treatment would enhance the corrosion resistance of the REM conversion coating. The cathodic polarization and anodic polarization were retarded by REM conversion coating, resulting in an improved corrosion resistance.     

Catalytic Incineration of C2H5SH and Its Mixture with CH3SH over a Pt/Al2O3 Catalyst

Catalytic incineration is one of the cost-effective technologies to solve troublesome volatile organic compounds. However, some sulfur containing volatile organic compounds, such as ethyl mercaptan, may deactivate the Pt catalyst that is commonly used in the catalytic incineration process. This paper provides information on the poisoning effect of ethyl mercaptan. The catalytic incineration of ethyl mercaptan, typically emitted from the petrochemical industry, over a Pt/Al2O3 fixed-bed catalytic reactor was studied. The effects of operating parameters including inlet temperature, space velocity, C2H5SH concentration, O2 concentration, and catalyst size were characterized. Catalytic incineration on a mixture of C2H5SH with CH3SH was also tested. The results show that the conversions of C2H5SH increase as the inlet temperature increases and the space velocity decreases. For the temperature from 200–260°C, the higher the C2H5SH concentration is, the lower its conversion. The O2 concentration has a positive effect on the conversion of C2H5SH. C2H5SH has a poisoning effect on the Pt/Al2O3 catalyst, especially at lower temperature. The existence of CH3SH has no effects on the conversion of C2H5SH.     

老化方式对聚氨酯涂层钢板失效行为的影响

运用四种加速方法对聚氨酯有机涂层钢板进行老化,并通过涂层的表观性能和电化学特征对比研究了老化方式对涂层失效的影响.紫外老化对涂层光泽的影响最大,老化32 d失光度达85.7%.盐雾实验前期线性极化阻力R_p迅速下降,后期由于盐膜的生成使得R_p保持稳定;氙灯和盐雾混合老化的光泽度和R_p的变化规律都表现为实验前期与光老化相似,后期则与盐雾实验相类似.此外,拟合不同老化方式的电化学交流阻抗谱发现:混合老化前期主要受氙灯影响,与单一氙灯老化的等效电路一致,表现为两个时间常数;后期产生盐膜,出现三个时间常数.      

冷却塔防腐涂层失效评价方法

在循环水和除盐水中进行了冷却塔酚醛环氧涂层和环氧煤焦沥青涂层试块的热水加速老化试验,测量了涂层试块在老化过程中的吸水率并观察了其形貌变化.通过分析涂层试块吸水率随吸水时间和老化时间的变化规律,研究了循环水冷却塔防腐涂层使用寿命的评价方法.发现根据冷却塔涂层试块老化过程中的吸水率-老化时间曲线拐点可推算出涂层在试验温度下的使用寿命,然后再根据范特霍夫(Vant Hoff)规则可推算出涂层在实际运行工况下的使用寿命.      

吹扫捕集与色谱—质谱联用分析宝钢水和废水中VOCs

吹扫捕集与色谱—质谱联用技术是一种较为成熟的有机物分析技术,结合实验室仪器条件采用此技术,开发出依据美国环保局(EPA)8260B方法分析水和废水中挥发性有机物(VOCs)的方法,并应用于宝钢实际水样的监测,取得了较好的分析结果。该方法可分析40种(类)挥发性有机物,每种物质分析的线性相关系数都能达到0.99以上,基体加标试剂的回收率为89.5%～102.7%,除四种物质为0.01mg/L外,其余物质的定量下限基本上为0.005mg/L,完全能够满足应用要求。     

National annual dioxin emissions estimate for hazardous waste incinerators

Reducing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans, commonly known as dioxins, is a high priority for environmental regulatory bodies throughout much of the world. In the United States, Section 112 (c)(6) of the Clean Air Act (CAA) requires the Environmental Protection Agency (EPA) to identify and control emissions from sources that are responsible for at least 90% of the overall emissions of seven targeted hazardous air pollutants, including dioxins. On April 19, 1996, the EPA proposed Maximum Achievable Control Technology (MACT) Standards for Hazardous Waste Combustors (HWCs). In that preamble, the EPA estimated annual dioxin emissions from the nation's hazardous waste incinerators (HWIs) to be 79 grams expressed as 2,3,7,8 tetrachloro dibenzo-p-dioxins (TCDD) international toxic equivalents (ITEQs). However, early EPA dioxin emission estimates from medical waste incinerators and cement kilns were significantly overestimated; so, the following independent national dioxin emissions estimate for HWIs was prepared. This estimate corrects the errors in the EPA's HWI emissions database, uses an updated inventory of HWIs in the United States, and applies statistical imputation techniques that take maximum advantage of the limited dioxin emissions data for HWIs.     

Permeation of BTEX through Unaged and Aged HDPE Geomembranes

The effects of aging of high-density polyethylene (HDPE) geomembranes on the diffusion and partitioning of a group of volatile organic compounds (VOCs) are examined. Two different 1.5?mm thick HDPE geomembranes were aged in the laboratory at 85°C by immersing in a synthetic leachate for up to 32?months. The results of partitioning and diffusion tests performed at room temperature on both unaged and aged geomembranes using a dilute aqueous solution containing four VOCs commonly found in landfill leachates [benzene, toluene, ethylbenzene, and xylenes (BTEX)] are reported. The diffusion and partitioning coefficients decreased with increased aging. The calculated permeation coefficients decreased by 36–62% after aging the geomembrane for about 10–32?months. This decrease in diffusion, partitioning, and permeation coefficients is related to the increase in geomembrane crystallinity during aging. A relationship between partitioning, diffusion, and permeation coefficients with the geomembrane crystallinity is established and could potentially be used to evaluate the migration of VOCs through HDPE geomembranes. Aging of HDPE geomembrane did not increase diffusive transport of organic contaminants.     

Ultrasonic signaling in the gerbil (Meriones unguiculatus): Social interaction and olfaction.

Conducted 3 experiments with 53 gerbils to assess the conditions for ultrasonic emission. Exp I indicates that isolated Ss rarely emitted ultrasounds, males emitted at a higher rate than females, and emission rates ordinarily decreased with continual testing. Ultrasonic emissions were stimulated by olfactory cues from conspecifics. Exp II demonstrates that dominant males emitted more ultrasounds than subordinate males and responded to cues from anesthetized, shaved, or dead animals or from anesthetized animals in the dark. Exp III shows that body hair elicited ultrasounds from males unless organic materials were removed from the hair with chloroform. Hair was an effective stimulus at a distance only when an airstream blew the volatiles over the recipient. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

低烧损 复合粉末制备及涂层抗烧蚀性能研究

采用喷雾造粒-胶粘包覆的方法制备了一种低烧损核壳结构 ZrB2/SiC 复合粉末, 研究了胶粘包覆过程中不同清漆含量对粉末包覆效果的影响。 结果表明清漆含量不足时细粉包覆不完全, 细粉出现单独团聚的现象; 清漆含量过多时, 造成原始球形颗粒的粘连; 当清漆含量为 4.5% 时, 获得包覆效果良好的粉末, 外层包覆完整均 匀。 为了研究等离子喷涂过程中核壳结构粉末 SiC 发生分解烧损程度, 对比了分别采用核壳结构和均匀弥散结构ZrB2/SiC 复合粉末所制备涂层的微观形貌及涂层中元素分布。 结果表明核壳结构粉末喷涂涂层成分均匀性良好,高熔点 ZrB2 保护内层 SiC, 可有效减少 SiC 在等离子焰流中的烧损, 实现涂层和粉末成分的一致性。 对核壳结构复合粉末制备的涂层进行了 20s 的氧-乙炔火焰烧蚀试验, 涂层质量烧蚀率为 1.837×10-3g/s, 对涂层抗烧蚀机理进行了初步探讨。     

用于海洋环境下活化腐蚀防护的高性能电弧喷涂层

采用铝或锌涂层的活性腐蚀防护是热喷涂技术应用最多的领域.每年大约要消耗20,000吨的喷涂线材,并且未来需求还在增加.热喷涂技术及材料无论是单独还是一起在海洋环境下使用,都有一定的标准.海上风力发电机（OWET）要求维护间隔时间尽可能长,这可以通过使用长寿命的表面涂层来满足使用要求.目前,金属喷涂涂层主要用于OWET的高应力部件,如法兰、框架和安装面.在实验室测试的过程中,研究了多种用于OWET的双涂层体系的抗腐蚀效果,其中金属涂层关注最多.制备了不同厚度和特性的Zn/A1和Al涂层,对部分涂层进行封孔处理,并制备有机涂层形成多层涂层体系.其目的之一是制备地氧含量的防护涂层,并和目前标准的工艺进行对比.依照ISO20340标准[5]对涂层和标样涂层的抗腐蚀性能进行了25周的循环老化测试评价,评估标准为：涂层划痕处的腐蚀和渗透、涂层起泡和锈蚀程度,以及涂层与基材的结合力.测试结果表明,喷涂金属涂层是一种有效的改善材料的抗腐蚀性能方法.采用活性气体作雾化气体的电弧喷涂或冷喷涂制备Zn/A115涂层能够提升涂层的防护效果,并且可以降低涂层的厚度,具有较好的经济前景.     

Prevention of intellectual disabilities: early interventions to improve cognitive development

The isothermal enthalpy changes with time of a dental composite were examined by microcalorimetry to isolate the effects of different filler concentrations and curing times on chemical aging of these composites. Urethane dimethacrylate (UDMA) monomer, zirconia-silica (ZS) powder, and 3-methacryloxypropyltrimethoxysilane (MAPM) were used as organic and inorganic matrices, and a coupling agent, respectively. The composite was mixed in different ratios and cured by visible light. The enthalpy changes with time for 0, 15, 45, 75% ZS-filled UDMA and 75% MAPM-silanated ZS-filled UDMA cured for 13, 30, 90, 150, and 300 s were measured at 37.0 degrees, 57.0 degrees, and 65.5 degrees C until equilibrium. Increased curing time and filler concentration caused the excess enthalpy changes (dH) and their rate of change (dH/dt) to increase with annealing time and apparent equilibrium was reached faster. In addition, dH showed nonlinear dependence with the increase in filler concentration by showing a maxima for samples containing 25 wt% filler. Further, filler silanation caused dH/dt to increase and required shorter times to reach apparent equilibrium. dH also reached a minimum when samples contained silanated filler, compared to composites containing unsilanated filler. It was concluded that the shorter curing time caused the occurrence of spontaneous densification, which facilitated continual resin curing; and longer curing time caused higher crosslinking of the organic phase. Moderate concentration of inorganic phase restricts the molecular motion of the surface layer of polymer onto filler particles, and the polymer is regarded as highly crosslinked, while a higher filler concentration forms aggregates that are covered by the polymer which causes a decrease in the molecular packing of the resin, and is reflected as low enthalpy values. Finally, silanation of the filler showed a highly endothermic reaction that is probably due to breaking and forming of bonds at the interface between the organic and the inorganic phases in the composites.     

Amniotic septostomy for the treatment of twin oligohydramnios-polyhydramnios sequence

A mass balance for lead for the year 1989 in the South Coast Air Basin has inputs to the atmosphere of 600 +/- 190 kg/day and outputs of 580 +/- 160 kg/day, showing rough agreement. Stationary sources are responsible for only about 5% of the total lead emissions. The bulk of the lead is emitted from vehicles using leaded gasoline (37%) and unleaded gasoline (15%), as well as from resuspension of previously deposited lead on roads (43%). Over half of the total emitted lead deposits on roads and nearby soil, while about one-third is carried out the basin by wind. A small amount, less than 10%, is deposited on surfaces throughout the basin. These percentages are approximately the same as those in a mass balance for the same region calculated for 1972, when lead emissions from leaded gasoline were about a factor of 70 greater than leaded gas emissions in 1989. When the lead emissions are used as inputs to a simple continuously stirred flow reactor model for the basin, reasonable agreement is obtained between calculated and measured concentrations.     

Ethylene glycol ethers: an environmental risk assessment

Ethylene glycol ethers and acetates are used as intermediates, solvents, and plasticizers. They primarily enter the environment from manufacturing effluents and emissions and during their use in commercial products. Therefore, an examination of their ultimate fate and toxicity, as well as their potential for exposure, was performed. Overall, these data show that ethylene glycol ethers and acetates are not persistent in the environment, are not bioaccumulative, are generally classified by U.S. Environmental Protection Agency (EPA) procedures as "practically non-toxic" to aquatic organisms based on acute toxicity, and that conservatively calculated exposures are mostly below concentrations of concern for chronic risks to aquatic life.     

钛表面改性Al/NiCu组合涂层反应机理及抗氧化性能

采用等离子结合电弧喷涂的工艺方法在工业纯钛表面制备了Al/NiCu组合涂层,在700℃的大气环境下对Al/NiCu/Ti试件进行加热处理,使得Al、NiCu复合涂层之间发生扩散反应并原位生成具有一定抗高温氧化性能的Ni-Al金属间化合物涂层.对加热改性处理前后涂层的微观组织及Ni-Al金属间化合物的形成机理进行了研究,...