Metal fractionation of atmospheric aerosols via sequential chemical extraction: a review

This review surveys schemes used to sequentially chemically fractionate metals and metalloids present in airborne particulate matter. It focuses mainly on sequential chemical fractionation schemes published over the last 15 years. These schemes have been classified into five main categories: (1) based on Tessiers procedure, (2) based on Chesters procedure, (3) based on Zatkas procedure, (4) based on BCR procedure, and (5) other procedures. The operational characteristics as well as the state of the art in metal fractionation of airborne particulate matter, fly ashes and workroom aerosols, in terms of applications, optimizations and innovations, are also described. Many references to other works in this area are provided.     

固相微萃取气质联用技术对卷烟烟丝和卷烟烟气总粒相物中挥发性和半挥发性成分的研究

采用固相微萃取－气相色谱－质谱（SPME－GC－MS）法对成品卷烟烟丝和卷烟烟气总粒相物中挥发性和半挥发性成分进行了分析鉴定，并对鉴定出的70种成分和96种成分进行了比较。     

复合聚并协同脱除燃煤颗粒物及颗粒态重金属的中试研究

燃煤颗粒物和其上富集的As、Se、Pb等重金属排入大气后危害环境和人体健康。本研究开发以湍流聚并、壁面回流吸附为原理的复合聚并器，研究了聚并前后对颗粒物和颗粒态重金属的聚并效果。首先采用数值模拟方法综合考虑压力损失、速度均匀性和颗粒物聚并效果，优选了折叶片作为复合聚并器的叶片类型。随后进行了不同流量的颗粒物聚并中试研究，发现复合聚并器对PM₁的聚并率可达32.84%，随着流量从11.1 m/s增加到17.6 m/s，PM_2.5聚并率呈现一定下降趋势，说明了流量增加导致颗粒停留时间缩短和颗粒物聚并率的下降。通过对比聚并前后颗粒物中As、Se、Pb的浓度变化，发现聚并过程增强了对气态重金属的吸附，也会聚集富含重金属的纳米级颗粒物，从而造成PM₁中重金属浓度的增加。聚并后PM₁内的As、Se、Pb绝对浓度的降低，显示了复合聚并器对颗粒物和颗粒态重金属的协同脱除效果。     

自然水体悬浮颗粒物中主要化学组分对铅、铜的吸附作用——实验室模拟吸附特征与水环境中富集特征的比较

利用主要组分萃取-吸附-统计分析方法研究了自然水体悬浮颗粒物样品中主要化学组分对铅、铜的吸附特征, 并采用天然悬浮颗粒物样品直接萃取的方法研究了实际水环境中悬浮颗粒物样品各组分对重金属的富集特征, 通过二者对比进一步研究了悬浮颗粒物中主要化学组分在铅、铜吸附中的作用. 结果表明, 悬浮颗粒物样品中各组分的吸附特征与富集特征具有较好的可比性, 铅主要与颗粒物中的铁氧化物相结合, 铜则主要与有机质相结合.     

Physico-chemical characterization of crystalline phases in fly ashes

Fuel oil combustion in power plants, domestic heating systems and diesel engines, causes the emission in the environment of particles with a typical structure and composition: the cenospheres.These particles are produced during the microdrop fuel oil combustion, when air and fuel are injected into the combustion chamber; they have a spheroidal morphology and a spongy structure.Cenospheres are constituted by an amorphous component rich in C, S, Si, Fe and Al; phases composed by microcrystals of sulphates, oxides and pure metallic elements or their alloys, are frequently present in the cenospheres.These crystalline phases are important from environmental and toxicological points of view both because they are composed of heavy metals, and because they can play an important role in heterogeneous catalysis.We started to study these crystalline phases by analytical electron microscopy techniques and electron energy loss spectrometry to define and characterise their structure and composition.     

Urinary levoglucosan as a biomarker for residential wood smoke exposure

As part of a randomised controlled residential intervention study, levoglucosan (LG) was investigated as a biomarker for wood smoke exposure. This study was conducted among 33 children living in homes that used wood stoves for residential heating. Indoor fine particulate matter (PM_2.5) concentrations and corresponding urine samples from participants were collected during pre- and a post-intervention winter sampling periods. Interventions included the installation of an air filtration unit and a wood stove change out. Homes and children assigned to a placebo filter served as the control condition. Results showed a strong reduction in indoor PM_2.5 among the air filter homes (≈58% reduction), whereas the wood stove change out homes did not have a significant PM_2.5 reduction from pre- to post-intervention observations. Children living in the air filter homes did not show a corresponding reduction in urinary LG concentrations. Further analysis did not show an association between overall changes in indoor PM_2.5 concentrations and changes in urinary LG concentrations. These findings suggest that urinary LG is not a reliable indicator of wood smoke exposure in residential wood heating settings.     

Characterization of nanometric carbon materials by time-resolved fluorescence polarization anisotropy

In this work, time-resolved fluorescence polarization anisotropy (TRFPA) technique has been applied to the determination of the average size of asphaltenes and combustion-generated carbon nanoparticles. The characteristic depolarization time of fluorescence light following photon absorption is related to the typical particle size through the Stoke–Einstein rotational diffusion equation. The TRFPA technique employed in our experiment achieves sub-nanosecond time resolution, roughly corresponding to sub-nanometer accuracy in determining the particle size. The technique has been applied to both asphaltene and carbon nanoparticles, the former being a component of petroleum, whereas the latter result from combustion processes. Therefore, a complete and reliable characterization of such particles is of great importance in oil industry and atmospheric physics, respectively. Although the TRFPA technique has been developed and widely used on molecular and biological samples, it proves to be a very powerful tool for measuring the size of asphaltene and soot particles as small as few nanometers with a resolution of the order of 0.1 nm.     

Preparation of Composite Filters Based on Porous Coordination Polymers by Using a Vacuum Filtration Method for Highly Efficient Removal of Particulate Matters

In this study, two novel crystal materials pcp1 and pcp1‐L have been synthesized successfully. The different conformations of the two crystals are mainly attributed to the introduction of the Schiff‐base ligand L ( L =(E)‐4‐methyl‐N‐((6‐methoxypyridin‐2‐yl)methylene)aniline). Subsequently, pcp1 and pcp1‐L composites have been firstly produced by a vacuum filtration method on various substrates (i.e., melamine foam, plastic mesh, carbon fiber cloth and glass cloth). The obtained robust composites show excellent performance in removing PMs owing to high ζ potential, microporous structure, large conjugation system and electron cloud‐exposed metal center (DFT calculations) of pcp1 and pcp1‐L . Particularly, pcp1‐L @glass cloth with low pressure drop exhibits high thermal stability and high long‐term reproducibility. Additionally, the high removal efficiency of pcp1‐L @glass cloth towards particulate matters could also be maintained, even achieving >99.9 % in the car exhaust gas field test.     

Comparison of extracting solutions for elemental fractionation in airborne particulate matter

It is here described the comparison of extraction efficiency of some solutions (acetate buffer, deionized water, diluted HNO₃ and EDTA) frequently adopted in literature for evaluating the elemental solubility in airborne particulate matter. This comparison was performed considering the distribution of As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, S, Si, Sb, Sn, Sr, Ti, V, Zn between the extractable and mineralized residual fractions on the NIST 1648 certified material, PM₁₀ real samples and size-segregated samples, collected by a 13-stage impactor.The extracting solutions were evaluated by comparing extractive efficiencies and robustness towards some factors, such as acidity and concentration of complexing species, that have great environmental variability and that could be able to modify the extractive efficiency.Furthermore, extraction methods application to size-segregated samples allowed estimating the selectivity of extracting solutions towards dimensionally characterized emission sources, as dusts originated from abrasion and road dust re-suspension.On the basis of the obtained results, it was possible to define the main advantages and disadvantages resulting from the use of different extracting solutions, necessary to make possible the comparison of environmental studies carried out in different extractive conditions and to start up a proper study for harmonizing extracting procedures.