木家具中挥发性有机物的散发传质特性

建立了新的木家具挥发物散发完全解析模型,全面考虑了各种传质机理和污染物阻力,同时适用于有无换气的模拟. 经分析模型提出了一套简捷的新实验方法,利用同一家具在密封箱中若干释放周期的稳态和实时浓度,同时求取目标污染物的4个重要传质参数：可散发量C0、扩散系数D、分配系数K和对流传质系数h. 测定了(23±0.5)℃、相对湿度45%±5%下某家具中甲醛和总挥发物的传质参数,甲醛C0=4994 mg/m3, D=4.05′10-10 m2/s, K=499, h=1.4′10-3 m/s;总挥发物C0=19939 mg/m3, D=2.12′10-10 m2/s, K=1001, h=5.0′10-4 m/s,均落于常见范围,与其他方法所得对应参数的变异系数小于0.5%. 将参数代入数值算法预测有无换气条件下气候箱中的散发浓度,与实验值的平均偏差小于3.5%.     

测定建材散发关键参数的密闭舱C-history方法与其他方法的比较

室内建材中散发的挥发性有机物(VOC)所引起的空气品质问题显著影响着人们的健康、舒适和工作效率。目前有不少测定建材VOC散发3大关键参数(初始可散发浓度、分配系数和扩散系数)的密闭舱方法,本文将最近提出的密闭舱C-history方法与其他密闭舱测定散发关键参数的方法(多次散发回归法、多平衡态回归法及多气固比法)进行了比较研究。结果表明,密闭舱C-history方法与其他测试方法对于所选建材中目标VOC散发关键参数测定的最大偏差均不超过25%。而密闭舱C-history方法只需在密闭舱中对建材执行一次散发过程即可求得上述3大关键参数,通常不超过3d,大大节省了实验时间,因而比其他方法更便于工程应用。     

直流舱测定材料VOC散发关键参数的浓度轨迹法

室内及车内环境中材料散发的挥发性有机化合物(VOC)是造成空气品质低劣的重要因素之一, 显著影响着人们的舒适度和身体健康。材料VOC散发特性由3个关键参数表征:初始可散发浓度C₀、扩散系数D_m和分配系数K。测定上述散发关键参数是研究材料VOC散发规律进而预测人体暴露和健康风险的基础。基于目前应用最广泛的直流舱中材料VOC的散发过程, 提出了同时测定C₀和D_m的浓度轨迹法。该方法通过预设K值, 然后对环境舱浓度的对数进行线性拟合, 根据斜率和截距获得关键参数C₀和D_m。敏感性分析表明, 不同的K值对测定的C₀和D_m值影响很小。通过对文献中的直流舱散发实验数据进行处理, 结果表明该测定方法具有较高的精度。     

木家具表面挥发性污染物散发传质特性

木家具表面挥发性污染物的散发是一类污染环境的复杂传质行为。为准确把握传质特性,首先建立了一套更完善的新式完全解析模型,综合考虑了两大传质机理(扩散、对流)、气候箱中污染物阻力、背景浓度和进气浓度,同时适用于无换气或换气条件下的模拟研究;例如,预测气候箱或木家具中污染物浓度变化,评价传质速率或散发量,以及估算室内浓度达标时限。然后通过对模型的分析提出了一套简便快捷的新式实验法,利用木家具在换气箱中散发的逐时浓度,一并求取目标污染物的3个重要传质参数:可散发量ρ₀、扩散系数δ和分配系数β。实验部分使用该换气箱法测算了某密度板家具中甲醛和总挥发性有机化合物的ρ₀、δ和β,与文献中基于密封箱的数据处理方法所得结果的变异系数小于5%,并有效避免了出现负压等密封箱采样可能导致的潜在问题。将传质参数代入数值算法预测了密封箱和换气箱中木家具散发挥发性污染物的浓度变化,与实验测量的数据吻合良好。该模型和方法能够准确预测或测定木家具表面挥发性污染物传质特性。     

沸石粉对PP中VOC散发性能的影响

报道了利用沸石粉减少聚丙烯(PP)中挥发性有机化合物(VOC)的方法.通过调整烘烤、挤出工艺等方法优化了PP中VOC散发性能,并利用气相色谱-质谱联用仪对结果进行表征.结果表明,将PP以110℃烘烤18 h,并与2份沸石粉共混后在挤出机内210℃下真空挤出是最佳挤出工艺.在该条件下,PP中TVOC散发浓度在10307μg/m3左右,表明该方法具有一定的开发价值.     

水性涂料中VOC测定的研究进展

简单介绍了各国挥发性有机化合物(VOC)的定义,以及国内外测定VOC含量的标准和方法。指出了当前测定水性涂料中VOC遇到的难题。阐述了水性涂料的发展趋势。     

袋式法测试车用塑料VOC散发量的方法研究

采用聚丙烯(PP)和聚甲醛(POM)塑料为实验样品,使用袋式法进行VOC(挥发性有机化合物)测试,考察不同采样袋体积和取样量对VOC散发量的影响。结果表明,在同样采样袋体积和散发空间下,改变样品的取样量,散发量和取样量相关系数大于0.7;等比例改变采样袋体积和取样量时,对各物质的散发浓度影响较小,相对偏差在30%以内;采用袋式法测试PP和POM塑料中VOC散发量相对标准偏差均小于15%,方法的重复性较好。     

多组分传质过程模拟研究进展

在传质过程的模拟研究中。传统上长期使用的平衡级模型存在不少缺点。Taylor等人在上世纪80年代中期提出了非平衡级模型。该模型适用于所有可能情况，又可以根据实际的物系和分离条件作相适应的简化，比较符合实际情况。自该模型提出以来，得到了越来越广泛的研究和应用，多组分物系传质过程的模拟研究也进入了一个新阶段。本文综述多组分物系传质过程的模拟研究进展，并着重介绍非平衡级模型及其应用。     

粉末涂料中挥发性有机化合物(VOC)含量的测定

建立了粉末涂料中挥发性有机化合物(VOC)含量的气相色谱检测方法,对方法的线性范围、检出限、精密度和回收率均进行了研究。实验表明,该方法对粉末样品中包括乙醇、甲苯等在内的23种VOC组分均有很好的适用性,方法的精密度和回收率均令人满意。该方法可用于粉末涂料中挥发性有机化合物的定性和定量分析。     

轨道车辆用单组分聚氨酯发泡胶VOC散发及气味研究

以两款轨道车辆内饰用聚氨酯发泡胶样品中挥发性有机化合物(VOC)散发情况为研究对象,先通过重量法确定平衡阶段时间和散发特性,并用常规的袋式法对不同平衡时间的样品进行检测,获得聚氨酯发泡胶成型样品的散发特性,通过嗅阈值和阈稀释倍数对样品气味进行评价。结果表明,重量法和袋式法相结合可以实现对成型后聚氨酯发泡胶VOC散发情况的评估,并能得到聚氨酯发泡胶VOC主要贡献物质,通过嗅阈值和阈稀释倍数的换算实现对聚氨酯发泡胶气味的溯源和定性的评价方法,与常规的VDA270定性结果有很好的一致性。     

湿建筑材料中VOC释放规律

湿建筑材料中挥发性有机物（volatile organic compound,VOC）释放过程是一个非常复杂的物理过程,其中包括材料本身的干燥过程以及质量传递过程。为探讨湿建筑材料中VOC的释放机理,本文建立了描述湿建筑材料中VOC释放过程的物理模型,模型考虑了湿建筑材料中VOC释放过程中的干燥过程,并用该模型分析了VOC的饱和蒸气压在整个VOC释放过程中的作用机理。把该模型的计算结果与VB模型求解结果、Yang等建立的模型求解结果以及实验结果进行了对比,得出干燥模型计算结果与Yang等建立的模型计算结果以及实验数据吻合较好,较VB模型能更准确地描述VOC的扩散过程。通过不同工况下环境小室的实验数据,对温度与相对湿度对湿建筑材料中VOC释放过程的影响规律进行了分析。     

Evaluation of VOC emission and sorption characteristics of low-VOC adhesive-bonded building materials

To reduce the risk of indoor air pollution caused by synthetic building materials, low-volitile organic compounds (VOC) building materials, including adhesives, are commonly used in building construction. Although adhesives do not directly contact indoor air, they affect VOC mass transfer at the surface of finishing materials by diffusion. This study investigates VOC emission and sorption behaviors of building materials with low-VOC adhesives. Small chamber emission and sorption experiments were designed in parallel to field measurements to examine the onsite VOC emission and sorption rates of adhesive-bonded building materials. It was found that the onsite emission rates from a wallpaper composite (polyvinyl chloride wallpaper?+?paper adhesive?+?gypsum board) were higher than the emission rates detected in the small-scale chamber, which demonstrates the possible sorption effect of the wallpaper composite. The results of the sorption chamber experiment confirm that the wallpaper is a sorptive building material and that the bonding of wallpaper to gypsum board increases the sorption and re-emission rates. These results indicate that even though low-VOC adhesive-bonded materials are used, additional indoor air quality control techniques should be applied to minimize re-emission by sorption processes over long periods of time.     

Control of emission rates of chemical compounds emitted by controlling their mass transfer coefficients on the surface of the tested building material

The air change rate in the chamber, the loading factor of the materials, and the mass transfer coefficient are very important factors in the measurement of chemical compounds, because they have a decisive effect on emission rates of chemical compounds emitted from materials. Small 20-liter chambers, such as the advanced pollution and air quality chamber, are generally used in Korea and Japan for measuring the amount of released chemicals. In this study, chemical compounds released from building materials and adhesives were measured using a chamber proposed by the authors to control the mass transfer coefficient on the surface of the tested building material and we examined the distribution of chemical compounds concentrations in the chamber by means of computational fluid dynamics to confirm test reliability. The chamber was controlled and maintained at 28?°C, a relative humidity of 50%, a mass transfer coefficient of 14?m/h with an air change rate of 0.50?h^?1, and formaldehyde and total volatile organic compounds were emitted from the flooring material and adhesive. As the mass transfer coefficient on the surface of the tested building material increased, the emission rates of chemical compounds measured using the proposed chamber increased. The mass transfer coefficient on the surface of the tested building material significantly influenced the emission rates of the chemical compounds released from the building material and adhesive.     

Development of a test method using a VOC analyzer to measure VOC emission from adhesives for building materials

A volatile organic compound (VOC) analyzer is a portable device to measure the four main aromatic hydrocarbon gases: toluene, ethylbenzene, xylene and styrene. With the VOC analyzer, a semiconductor gas sensor eliminates the need for the carrier gas which is required for conventional gas chromatography. In addition, since the semiconductor gas sensor is supersensitive to gas components, it is not necessary to use a conventional gas concentrator or other complicated equipment. Compared with other measurement methods, the VOC analyzer is useful for measuring toluene, ethylbenzene, xylene and styrene in new buildings because of its ease in obtaining field results and repeating the test. For easy, fast and economic testing of total (TVOC) emission from adhesives used for building materials, we developed a test method using the VOC analyzer and compared its measurement of VOC emissions from building materials such as adhesives, paints and wood-based panels with that of the 20-l chamber method, which is the standardized test method in Korea. There was a good correlation between the TVOC emission concentrations determined by the VOC analyzer and the TVOC emission factor (EF) by the 20-l chamber. Based on this good correlation, the VOC analyzer is expected to gain widespread use in the manufacturing field application where a quick and easy test for VOC emission from adhesives for building materials is required. Furthermore, the VOC analyzer offers the potential to become an easier, faster and more economical technique than the currently used standard methods.     

Values of the mass transfer coefficient of the linear driving force model for VOC adsorption on activated carbons

Modelling of activated carbon cartridges is essential in personal protective equipments against toxic gases in order to know the duration of protection. The linear driving force model seems to be more adapted than the actual Wheeler–Jonas model because it has more physical significance. The difficulty is that the mass transfer coefficient can not be calculated a priori. Values of the LDF mass transfer coefficient are disseminated in the literature and thus there is no overview of the range and variations with different adsorbents, adsorbates and concentrations. The object of this paper is thus twofold: obtaining values of the mass transfer coefficient at different concentrations and adsorbates in order to have a comprehensive view of variations and appreciating the validity of the LDF constant pattern model.