关于水性涂料中有机挥发分(VOC)测定方法的讨论

论述了国家标准 (GB 1 85 82 -2 0 0 1 )、行业标准 (HBC 1 2 -2 0 0 2 )在VOC含量的计算以及测试方法的差异 ,VOC的测定偏差 ,标准的适用范围。介绍国外检测低VOC涂料的方法标准 ,并利用ISO、DIN标准方法对低VOC含量的涂料进行测试比较。

煤液化残渣中残留催化剂对其挥发分测定的影响

用热重分析仪对兖州煤加氢液化残渣 (THF不溶物 )的工业分析进行了测定 ,重点考察了液化催化剂对其挥发分收率测定的影响。比较了相同液化条件下残渣的挥发分收率 ,发现催化液化残渣的总挥发分 (GB法测定的挥发分含量 )比热液化的高。通过对TG DTG谱图的分析 ,确定了失重峰的归属 ,同时定义 110℃～ 70 0℃间的挥发分V70 0 为有机挥发分 ,该值与这两种残渣的H C比遵循共同的线性关系 ,而与添加的液化催化剂无关 。

Adsorptive and catalytic properties in the removal of volatile organic compounds over zeolite-based materials

Volatile organic compounds（VOCs） are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use of activated carbons as adsorbents and oxide-supported metals as catalysts. Notably, activated carbons easily adsorb water, which strongly hinders the adsorption of VOCs; conventional oxides typically possess relatively low surface areas and random pores, which effectively influence the catalytic conversion of VOCs. Zeolites, in contrast with activated carbons and oxides, can be designed to have very uniform and controllable micropores, in addition to tailored wettability properties, which can favor the selective adsorption of VOCs. In particular, zeolites with selective adsorptive properties when combined with catalytically active metals result in zeolite-supported metals exhibiting significantly improved performance in the catalytic combustion of VOCs compared with conventional oxide-supported catalysts. In this review, recent developments on VOC abatement by adsorptive and catalytic techniques over zeolite-based materials have been briefly summarized.

污水污泥直接用于烧砖的探讨

污水污泥可以有条件地用于烧砖。如果直接用作制砖泥料或添加料时,其有机质的挥发分在砖窑预热带析出,白白随烟气排出大气,损失70%的热值,并造成严重的甲烷二次污染。

Comparison of volatile constituents in two types of mugwort leaves(produced in Qichun and Nanyang) using the headspace GC-MS

Objective： To compare the volatile constituents in mugwort leaves produced in Qichun, Hubei Province and Nanyang, Henan Province. Methods： The volatile constituents were extracted using headspace heating and analyzed using gas chromatography-mass spectrometry （GC-MS）. Then a qualitative analysis was made according to the standard database provided by the National Institute of Standards and Technology （NIST） and the relative contents of each constituent were calculated using the peak area normalization method. Results： A total of 59 compounds were identified from the mugwort leaves from Qichun and 51 compounds were identified from the mugwort leaves from Nanyang. These mainly include monoterpenoids, sesquiterpenoids, C^HvOz and other compounds involving the aldehyde, ketone, alkane and benzene. The mugwort leaves from Qichun and Nanyang share 32 common volatile constituents. The chromatographic peak area of identified compounds accounting for 96.38% of GC-MS total chromatographic peak areain Qichun mugwort leaves, versus 95.54% of that in Nanyang mugwort leaves. Conclusion： The headspace heating extraction combined with GC-MS technology can evidently display similarities and differences of volatile constituents in mugwort leaves produced in different areas and thus provide scientific basis for the quality and screening of mugwort leaves.

Role of ammonia in forming secondary aerosols from gasoline vehicle exhaust

Ammonia(NH3) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols(SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds(VOCs), the influence of NH3 on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts(GVE) into a smog chamber with NH3 absorbed by denuders to examine the role of NH3 in particle formation from GVE. We found that removing NH3 from GVE would greatly suppress the formation and growth of particles. Adding NH3 into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH3-rich plumes. We also found that the presence of NH3 had no significant influence on SOA formation from GVE. Very similar oxygen to carbon(O:C) and hydrogen to carbon(H:C) ratios resolved by aerosol mass spectrometer with and without NH3 indicated that the presence of NH3 also had no impact on the average carbon oxidation state of SOA from GVE.

Design and synthesis of porous non-noble metal oxides for catalytic removal of VOCs

The design and synthesis of highly active non-noble metal oxide catalysts, such as transition- and rare-earth-metal oxides, have attracted significant attention because of their high efficiency and low cost and the resultant potential applications for the degradation of volatile organic compounds(VOCs). The structure-activity relationships have been well-studied and used to facilitate design of the structure and composition of highly active catalysts. Recently, non-noble metal oxides with porous structures have been used as catalysts for deep oxidation of VOCs, such as aromatic hydrocarbons, aliphatic compounds, aldehydes, and alcohols, with comparable activities to their noble metal counterparts. This review summarizes the growing literature regarding the use of porous metal oxides for the catalytic removal of VOCs, with emphasis on design of the composition and structure and typical synthetic technologies.

Optical characteristics and environmental pollutants detection of porous silicon microcavities

Porous silicon microcavities (PSM) optical crystals consisting of a Fabry-Perot microcavity embedded between two distributed Bragg reflectors have been fabricated by electrochemical etching. Scanning electron microscopy (SEM) clearly depicted their physical sandwich construction. The optical feature of the PSM structure was tuned by varying the anodization parameters. Through proper thermal oxidation and surface chemical modifications, the resulting structures were employed as optical sensors for the detection of environmental pollutants including volatile organic vapors (i.e. acetonitrile, toluene, cyclohexane, chloroform, acetone and ethanol) and interior decoration gases (i.e. toluene, ammonia and formaldehyde). Fourier transform infrared spectroscopy (FTIR) spectra confirmed the effective thermal annealing and surface modification chemistry, and the sensing process was accompanied by recording the modified structures' optical responses when exposed to target analytes. The PSM optical sensors showed good stability, sensitivity and selectivity, implying promising applications in gas sensing and en- vironmental monitoring.