Evaluation of VOC recovery strategies

Many manufactured items receive surface coatings for decoration and/or protection against damage. In a number of places along the production line emissions of (VOC) Volatile Organic Compounds can occur. Because VOC are a major contributor to photochemical smog, control of VOC emissions is a major concern for the industries' commitment to the environment. Approaches for process optimisation have a long tradition within chemical and process engineering for the systematic identification of cost- and resource-efficient production options. The challenge in the context of supply chain management is the optimal recovery and reuse of materials not only for single substances or energy flows in large chemical installations, but also for smaller production processes and various mass and energy flows within and between enterprises. Based on a case study from the industrial coating of bicycle frames, an approach for Multi Objective Pinch Analysis (MOPA) for the evaluation of overall recovery potentials for energy, water and VOC is presented. Moreover, a metric for resource efficiency is introduced as a measure for the possible savings potential and for the savings ultimately realised. This integrated approach requires a tight coupling of mass, energy, economic and environmental assessment methods and demands a highly interdisciplinary approach.

高固体分卷材涂料用聚酯的研制

通过引入叔碳酸缩水甘油酯单体,并采取分步聚合法工艺合成高固体分聚酯树脂,制得了施工 VOC满足环保要求的卷材涂料。探讨了不同二元酸类型、叔碳酸缩水甘油酯用量、相对分子质量及合成工艺对聚酯树脂及漆膜性能的影响。实验结果表明：采用分步法聚酯合成工艺,第一步选用甲基丙二醇及己二酸、六氢苯酐及苯酐合成的端羧基聚酯,酸超量 40%;第二步中引入叔碳酸缩水甘油酯及三羟甲基丙烷及甲基丙二醇,醇超量 50%,可得到数均相对分子质量为 1 862、固含量为 81%、黏度（ 23 ℃）为 1 860 mPa·s的高固体分聚酯树脂,以此树脂配制的白色卷材面漆性能良好,施工 VOC为 305 g/L,满足低于 420 g/L的要求。     

An efficient photo-catalytic VOC removal process by one-pot synthesized N-F/TiO2 nanoparticles in fluidized-spouted bed reactor

Photocatalytic degradation under visible light irradiation is an important task of using solar energy for the removal of environmental pollutants. N-F/TiO₂ nanoparticles were synthesized in one-pot sol–gel condition using tetra-isopropyl-orthotitanate as the TiO₂ precursor and NH₄F as the N-F doping source. Diffuse reflectance spectroscopy (DRS) analysis of the material has shown a reduction of band gap energy and shifting absorption edge to the visible wavelengths. A fluidized-spouted bed reactor equipped with the light source was designed and constructed for the oxidation process of VOC from the high airflow rate under Hg lamp irradiation using synthesized N-F/TiO₂ nanoparticles. Acetaldehyde was used as the air pollutant model molecule of VOC in this process. The effluent acetaldehyde concentration was analyzed continuously along the time by an online Gas Chromatography (GC) from the start up to reaching steady conditions. The results have revealed significant enhancement of acetaldehyde removal by the N-F/TiO₂ sample fabricated with an equal weight ratio of NH₄F/Ti. After steady conditions, almost 100% removal of acetaldehyde was observed in the spouted bed reactor from a high airflow stream of 5?L/min polluted with 1000?ppm acetaldehyde at room-temperature conditions, under 80?W Hg with 500 Lux intensity.     

Coupling ultraviolet photolysis and biofiltration for enhanced degradation of aromatic air pollutants

Coupling UV photolysis and biofiltration was evaluated as an effective treatment strategy for the enhanced degradation of hardly biodegradable aromatic volatile organic compounds (VOCs). o‐Xylene, a recalcitrant and poorly water‐soluble VOC, was used as a model compound and treated in two parallel treatment systems with and without UV pretreatment. Contaminated streams with flow rates of 0.186–0.384 m³ h^?1 and inlet o‐xylene concentrations of up to 0.22 g m^?3 were passed through the treatment system. About 20% (between 10 and 35%) of o‐xylene was converted into water‐soluble intermediates during the UV photolysis stage, which partially oxidized o‐xylene to more water‐soluble and biodegradable byproducts. The untreated contaminant along with the byproducts of UV photolysis was then removed effectively in the biofiltration stage, with improvements of up to 100% compared with the control biofiltration process. The results suggested that combined UV photolysis–biofiltration is promising as an effective technique to eliminate hydrophobic and recalcitrant organic compounds from contaminated air steams. Copyright © 2005 Society of Chemical Industry     

中国水性木器漆的现状和未来

本文通过对水性木器漆的原料、漆膜品质、技术要求和市场现状分析 ,对中国水性木器漆在未来几年内的市场走势和产品发展趋势作了展望。     

纳米材料TiO2光催化在IAQ中的应用研究

分析了纳米TiO2光催化处理室内VOC的反应机理，以三种室内常见的探发性有机物为例，分析了单一初始浓度、室内湿度、紫外光强、迎面风速、温度等因素的影响，及其与反应速率的曲线，并与动力学模型L－H进行比较，趋势预测结果满意。     

Seasonal cycle of VOCs in apartments

To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996-99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation.     

Exposure to volatile organic compounds (VOC) in public buses of Pamplona, Northern Spain

This study examines the exposure level of passengers and drivers to VOC in public buses in a medium-size metropolitan area (Northern Spain). In-vehicle monitoring was performed on different routes, on peak and non-peak hours, during January and February 2007. A total of 112 air samples were collected onto adsorbent tubes and analysed by thermal desorption (TD) and gas chromatography/mass selective detector (GC/MSD) technique. Statistical differences were found among route to route concentrations, with those routes with major prevalence in the commercial area of the city displaying higher values; differences between peak and non-peak hours were also observed. A decrease in VOC concentrations was also registered during the weekend. BTEX ratios were estimated and found to be related to traffic emissions and similar for all the surveyed routes. Correlations confirmed traffic as the main emission source for BTEX and trimethylbenzene, their concentrations being highly associated to changes in meteorological conditions.     

Fire Emissions of Organics into the Atmosphere

The mass of dioxins, PAH (polycyclic aromatic hydrocarbons) and VOC (volatile organic compounds) emitted from fires to the atmosphere in Sweden per year has been estimated. The estimate is based on the number of fires in buildings, vehicles, waste and forest fires in Sweden in 1999. It is estimated that the total emission of dioxins from fires is in the range 0.5–1.4 g TEQ. The total emissions of PAH and VOC are in the ranges 2–12 ton and 13–200 ton, respectively. The estimated emission of dioxins from fires approximately corresponds to the total emission from traffic or half the emissions from municipal waste combustion (Swedish data from 1993). The fire statistics show that the mass of material combusted in building fires during a year is approximately 7500 ton, while that from forest fires is 2600 ton. Additionally, 2000–3000 tons are combusted in vehicle fires, fires in containers, etc. In addition to the more common types of fires during a year, individual large incidents may contribute significantly to the total emission. Such incidents include fires in municipal landfills or specific waste storage facilities (such as those for used tyres). An assessment of the consequences of such incidents has been made. This assessment implies that a large contribution to the emission of dioxins could be expected from fires in landfills and from fires in waste plastics (PVC) and tyres. Fires in deposits of wood chips and tyres are also significant potential sources of PAH and VOC.     

长沙市住宅建筑室内外VOC浓度的实测与分析

根据10户住宅建筑的VOC浓度现场测试及问卷调查结果，分析了长沙市住宅室内外VOC浓度及个人暴露量的状况。分析了环境温湿度、住宅装修时间、空调气流组织方式等对住宅VOC散发及分布的影响。