Measurements and modeling of absorptive partitioning of volatile organic compounds to painted surfaces

Partitioning to surfaces is an important sink for volatile organic compounds (VOCs) indoors, but the mechanisms are not well understood or quantified. Here, a mass spectrometer was coupled to a portable surface reactor and a flow tube to measure partitioning of VOCs into paint films coated onto glass or wallboard, and their subsequent diffusion. A model was developed to extract values of the effective absorbing organic mass concentration of the film, C_w, which is a measure of absorption capacity, and VOC diffusion coefficients, D_f, from VOC time profiles measured during film passivation and depassivation. Values of C_w agreed well with the value estimated from the paint film mass and flow tube air volume, and D_f values (also measured using attenuated total reflectance-Fourier transform infrared spectroscopy) correlated well with VOC vapor saturation concentrations, C*, estimated using a group contribution method. The value of these relationships for estimating key parameters that control VOC partitioning into paint and the fate of VOCs indoors was demonstrated using a house model, which indicated that >50% of VOCs with C* ≤10⁸ μg/m³ (C* of octane, hexanone, and propanol) that contacted a paint film of typical thickness fully permeated the film regardless of emission duration.     

在线超低温预浓缩-全二维气相色谱-飞行时间质谱联用系统在大气挥发性有机物监测中的应用

采用自主研制的在线超低温预浓缩设备，连续在线采集大气样品或者连续采集苏玛罐离线样品，对样品进行超低温捕集浓缩和二次超低温冷冻聚焦，采用全二维气相色谱-飞行时间质谱联用技术分离检测浓缩后的挥发性有机物，实现对大气中C2~C12共100多种挥发性有机物的浓缩富集和定性定量分析。本研究对该方法的线性、重复性、加标回收率、检出限等性能进行表征，并与常规一维气相色谱-四极杆质谱联用系统的定性定量结果进行比较。结果表明，该方法不仅满足大气中挥发性有机物检测的性能指标要求，且组分定性定量的准确性、灵敏度等指标均优于一维气相色谱-四极杆质谱联用技术，在挥发性有机物成分较复杂的大气样品检测中具有明显优势。     

Wastewater desalination system utilizing a low‐temperature heat pump

A wastewater desalination system based on a low‐temperature air source heat pump was developed and studied in this paper. The system consists of 2 main parts: the wastewater flow process and the heat pump cycle. A series of experiments were conducted on the system under different conditions, and the effect of the evaporation temperature was investigated. This system can reach equilibrium at any evaporation temperature using the combination of the compressor and vacuum pump. To treat wastewater with low boiling point organic matter, the system was operated at a low evaporation temperature of 48°C. The organic matter remained in the concentrated wastewater, and the organic removal was approximately 97%. Three kilograms of treated water was produced in 1 hour with an energy consumption of 250 W. The performance ratio (PR) obtained from the experiments ranged from 4.6 to 7.3. The cost for treating 1 kg of water was 0.038 yuan CNY assuming 0.5 yuan CNY per kWh at the compressor frequency of 50 Hz.     

Indoor levels of volatile organic compounds at Florentine museum environments in Italy

Indoor Air Quality monitoring in cultural institutions is of particular concern to protect these places and the cultural heritage content. An indoor monitoring campaign was performed in three museums in Florence (Italy) to determine the occurrence and levels of volatile organic compounds (VOCs). VOCs of interest included BTEX (benzene, toluene, ethylbenzene, xylenes), terpenes, aldehydes, organic acids, and cyclic volatile methyl siloxanes (cVMS). The most abundant VOCs in all samples analyzed were BTEX, which were strictly related to the traffic source, followed by siloxanes and terpenes. Among BTEX, toluene was always the most abundant followed by xylenes, ethylbenzene, and benzene. cVMS in exhibition rooms with the presence of visitors showed higher values compared to samples collected when the museums were closed. Terpenes showed not only the influence of vegetation-biogenic sources surrounding a museum but could also be related to the wood used for the construction of showcases and furniture and the use of cleaning products. Data obtained also showed the presence of organic acids and aldehydes whose source can be traced back to exhibits themselves and wood-based furniture. Assessing the levels of organic acids in museums is important because, over time, it can cause deterioration of the artifacts.     

Protection efficiencies of surface-active inhibitors in zinc-air batteries

Zinc (Zn) particles in alkaline electrolyte of a Zn-air battery (ZAB) are unstable and prone to corrosion. Zinc oxide (ZnO) generated on the surface of Zn particles affects the electrochemical reactions and reduces the battery efficiency. Thus, inhibiting the self-corrosion rate of Zn particles has become acritical issue for the development of these batteries. In this study, a research endeavor has been attempted by employing three types and concentrations of organic inhibitors in ZABs to constrain Zn anode corrosion. Significant analyses like polarization curve, constant current discharge, AC impedance, and dendrite growth are executed for in-depth understanding of the influences of these inhibitors. The experimental results reveal that the inhibiting efficiency of 10 wt% Sodium dodecyl benzene sulfonate surpassed polyethylene glycol 600 (PEG 600) and polysorbate 20 (Tween 20), with a maximum current density of 476.20 mA/cm² and voltage output of 1.4 V along with discharge capacitance of 10.31 Ah for 2 hours and 8 minutes. Zn anode surface analysis exposes significant dendrite growth and elemental Zn required for passivation suppression. Nevertheless, the results are also justified by Nyquist and Bode plots. Thus, the selected inhibitor will proficiently guarantee the enhanced performance and stability of the ZABs obtained and provide enormous opportunities for its applications.     

酸性材料在CVOCs催化氧化中的应用

含氯挥发性有机化合物(CVOCs)对环境安全和人类健康存在持久性污染和危害。催化氧化法具有操作温度低和CO_2选择性高等优点,被广泛应用于CVOCs催化降解。催化剂作为CVOCs催化降解过程的核心部分,受到很多学者的关注。分析酸性分子筛、金属改性分子筛和复合氧化物酸性材料对各种CVOCs催化氧化活性、副产物控制性能、CO_2和HCl选择性的影响。结果表明,催化剂表面酸中心、氧化中心和催化剂表面结构性质在CVOCs催化氧化过程中起重要作用。较多酸中心和较大比表面积有利于CVOCs分子的吸附和活化,提高HCl选择性。而较多氧化中心则有利于CVOCs深度氧化,减少副产物产生,提高CO_2选择性。     

超声协助蒙脱土分散于聚磷酸铵阻燃聚丙烯的研究

阻燃剂能够增强聚丙烯（PP）的阻燃性能,但也会降低其力学性能,因此对阻燃剂进行改性以改善聚丙烯的力学性能显得至关重要。以传统的膨胀型阻燃剂（IFR）[由聚磷酸铵（APP）、季戊四醇（PER）、三聚氰胺（MA）组成]为PP阻燃。在合成APP过程中引入有机蒙脱土（OMt）。APP围绕OMt形成,剥离OMt使其能够较好地分散在阻燃剂中。为使OMt更好地分散在阻燃剂中,在磷酸氢二铵（DAP）、尿素（UREA）溶液中加入OMt,之后对溶液进行超声处理,蒸干后形成DAP-UREA-OMt与五氧化二磷反应生成APP。在PP中添加改性阻燃剂,有助于PP材料阻燃性能的提升与减缓力学性能的下降。当阻燃剂添加量为30%（阻燃剂添加量占总质量的质量分数）时,PP/IFR_APP/OMt复合材料的氧指数达到29.8%,通过V-0测试,拉伸强度为22.0 MPa,高出传统方法0.7 MPa。     

挥发性有机化合物催化氧化技术

基于环境友好,对使用催化氧化法去除挥发性有机化合物(VOCs)的原理、特点以及催化剂、工艺流程等研究进行综述。挥发性有机化合物完全催化氧化机理分为:Mars-van Krevelen(MVK)模型、Langmuir-Hinshelwood(L-H)模型和Eley-Rideal(E-R)模型。复合金属氧化物催化剂是研究的热点,去除VOCs的核心是使反应温度降低,即具有低温和高活性的催化剂。延长催化剂寿命、提高去除效率也可以带来良好的节能效果和降低投资成本。对于低浓度和大体积VOCs排放,可通过吸附+催化混合法先进技术实现去除,且成功应用于实践。