Determination of trace elements in automotive fuels by filter furnace atomic absorption spectrometry

The determination of Cd, Cr, Cu, Pb and Ni was performed in gasoline and diesel fuel samples by electrothermal atomic absorption spectrometry using the Transverse Heated Filter Atomizer (THFA). Thermal conditions were experimentally defined for the investigated elements. The elements were analyzed without addition of chemical modifiers, using organometallic standards for the calibration. Forty-microliter samples were injected into the THFA. Gasoline samples were analyzed directly, while diesel fuel samples were diluted 1:4 with n-heptane. The following characteristic masses were obtained: 0.8 pg Cd, 6.4 pg Cr, 12 pg Cu, 17 pg Pb and 27 pg Ni. The limits of determination for gasoline samples were 0.13 μg/kg Cd, 0.4 μg/kg Cr, 0.9 μg/kg Cu, 1.5 μg/kg Pb and 2.5 μg/kg Ni. The corresponding limit of determination for diesel fuel samples was approximately four times higher for all elements. The element recovery was performed using the addition of organometallic compounds to gasoline and diesel fuel samples and was between 85 and 105% for all elements investigated.     

Concentrations of elements in brain tumours

The aim of our experiments was to investigate the possible elemental concentration changes in brain tumours (glioblastoma multiforme). Our project also incorporated the determination of the regional distribution of elements in normal human brains. 17 elements (Na, K, Ca, Mg, Fe, P, S, Al, B, Ba, Co, Cr, Ni, Mn, Pb, Sr, Zn) have been measured in 21 different regions of 20 normal brains and in clinically and histopathologically selected brain regions of patients with brain tumours. Analyses were carried out by instrumental neutron activation analysis (INAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Quality control was ensured by using NBS Bovine Liver 1577a standard reference material. Comparison between the healthy and brain tumour concentration data using statistical evaluation revealed only a few elements (e.g. B, Zn, Sr) which showed significant differences as a consequence of the brain tumour.     

商业V_2O_5- WO_3/TiO_2催化剂重金属(Pb、Cu、Zn)中毒机理研究

采用浸渍法制备了不同含量重金属(Pb, Cu和Zn)中毒商业V_2O_5-WO_3/TiO_2催化剂,并对催化活性进行评估,重金属可明显导致催化活性降低.随着重金属浓度的增加,催化剂的失活程度加剧,而Cu和Zn的中毒效应低于Pb.结合XRD、 BET、 SEM、 NO-TPD、 NH_3-TPD、 H_2-TPR和in situ DRIFTS等方法对重金属中毒前后催化剂的理化性质进行分析.分析结果表明,失活是由化学和物理中毒的耦合作用引起的.相比于Fresh催化剂,中毒催化剂微孔和中孔有明显堵塞现象, BET比表面积减小,而中毒前后催化剂结晶度几乎没有变化,而中毒催化剂的表面覆盖了一层白色晶体,这可能导致活性位点被占据并阻碍NH_3在催化剂表面的吸附. in situ DRIFTS结果表明,重金属中毒后Br?nsted和Lewis酸位点的强度减弱,尤其是Br?nsted酸位点.此外,随着重金属含量的增加,中毒催化剂表面NO_2吸附量逐渐增加,从而促进N_2O的形成. H_2-TPR结果显示,还原峰的强度随着还原温度的升高而增强,表明重金属导致催化剂中的活性组分更难以参与SCR反应.     

生物质气化发电厂灰渣中微量元素的分布与富集规律

采用电感耦合等离子体发射光谱仪,研究了生物质气化发电厂灰渣中元素As、Al、Br、Ca、Cd、Cl、Cr、Cu、F、Fe、Ga、K、Mg、Mn、Na、Ni、P、Pb、S、Si、Sr、Ti、Zn在气化器底灰、淋洗器灰和旋风分离器灰中的质量分数,并分析了这些元素在不同粒径3种灰渣中的分布规律。结果表明,大部分极易挥发的元素,如卤族元素、碱金属元素主要在淋洗器中存在,表明了它们在飞灰颗粒中的富集。旋风分离器灰在灰渣中所占比例为10%左右,以粗灰为主,灰中Fe、Si、Ni、Pb、Zn、Cr、Cd为多;表明了此灰中重金属元素积累。在气化炉底灰中以K、S、Mn、Cu为主。元素随颗粒物粒径大小和元素性质的不同,呈现不同的富集规律。     

煤中痕量元素在循环流化床锅炉中的迁移行为与富集特性

对天津市某电厂循环流化床(CFB)锅炉燃用的原煤及燃烧产物底灰、飞灰、细飞灰(≤50 μm)进行痕量元素含量的测定,分析了Be、Zn、Hg、V、Cr、Mn、Co、Ni、Cu、As、Se、Cd、Pb 13种痕量元素在燃烧过程中的迁移行为,揭示了痕量元素在CFB锅炉中的分配、富集特性。结果表明,CFB锅炉中,较低的炉温对于痕量元素的迁移富集产生了较大的影响。由相对富集系数得知,Be、V、Co、Se在底灰中耗散,在飞灰中富集,Zn、Mn倾向于在底灰中富集,元素Cd、Pb、Ni、Cu挥发性较强,在底灰和飞灰中均是耗散。As受钙氧化物影响,挥发性表现并不明显。Hg在底灰和飞灰中相对富集系数均很低,表明Hg在整个燃烧过程中以气态形式排放;Hg、As、Se、V、Cr、Mn、Co、Ni、Cu、Zn、Pb均有向小颗粒物中富集的趋势。根据相对富集系数以及研究的13种元素在低温CFB锅炉中的迁移行为,将这些元素分为三类:A类(E_R<0.1),主要是以气态形式排放元素Hg;B类(0.1R≤0.85),较易挥发元素As、Be、Ni、Cu、Se、Cd、Pb、Co、V;C类(E_R>0.85),主要残留在固体产物中元素Zn、Mn、Cr。     

幼儿头发中微量元素含量相关性研究

为探讨儿童头发中微量元素是否有协同或拮抗作用,测定了646名1－3岁和3803名4－7岁儿童头发中的Zn,Fe,Cu,Ca,Mn和Pb含量,并研究了各元素间的相互关系,结果表明：1－3岁幼儿头发中Zn,Fe,Cu,Ca,Mn和Pb各元素间均呈正相关,4－7岁儿童的发锌含量与发铅含量呈非常显著负相关（P值均＜0．001）,其它各元素间均呈正相关。     

Assessment of trace elements characteristics and human health risk of exposure to ambient PM2.5 in Hangzhou,China

A method for simultaneously determining the trace elements in particulate matter (PM) (PM2.5) by inductively coupled plasma mass spectrometry was established. The PM2.5-loaded filter samples were digested under the optimised conditions including a mixture of HNO₃–HCl–HF with ultrasonication proceeding at 70°C for 2 h. Recoveries of 90.83–103.33% were achieved for 20 elements (Co, Sr, Ag, Cd, Sb, La, Ce, Sm, W etc.) in NIST standard reference material 1648a (urban PM). PM2.5 samples were collected at urban site in Hangzhou from August 2015 to November 2015. PM2.5 concentrations of 15% sampling days exceeded the daily limitation and the mean concentrations of PM2.5 from August to November reached the 66.4% of the limitation. PM2.5 concentrations in summer were higher than that in autumn. The concentration of Zn was highest, following with Al, Pb, Mn, Cu and As. Significant enrichment was observed in Mn, Zn, Pb, Ag, V, Ni, Cu, As, Se, Hg, Co, Cd and W, which was probably induced by vehicular exhaust, oil and residual fuel combustion and industrial emissions. The daily mass concentrations of PM2.5 and elements fluctuated significantly. Rainfall could significantly reduce the concentration of Ti, Mn, Cu, Zn, As, Se, Hg, Sr, Ag, Cd, Sb, La, Ce, Sm and Pb, and the risk levels of carcinogenic elements and non-carcinogenic elements in rain day were significantly lower (43.7–81.4%) than those in non-rain day. The risk levels of Co, Cd and As could lead to adverse health outcomes through the respiratory system, which should deserve more attention, while the risk levels of Ni and non-carcinogenic elements (Hg, Mn, Cu, Zn, Pb, V) were under average risk acceptance.     

Catalytic Reduction of Nitric Oxide on SiO2/AlO3-supported Transition Metal Catalysts

Selective reduction of nitric oxide in pressence of oxygen is one of the major challenges in the automobile exhaust after-treatment for lean-bum gasoline engines and diesel engines. Besides Cu-ZSM-5, Pt and Pd based noble metal catalysts, alumina-supported silver catalysts show high activities on NOx conversion to nitrogen^[1,2]. However, NO conversion activities over silver on binary oxides have rarely been studied in detail^[3], although copper on SiO₂-Al₂O₃ catalyst was reported to have a high activity^[4] Here, NOx reduction activities on SiO₂-Al₂O₃-supported transition metal catalysts prepared by sol-gel method was investigated.     

Pd–Pb Alloy Nanocrystals with Tailored Composition for Semihydrogenation: Taking Advantage of Catalyst Poisoning

Metallic nanocrystals (NCs) with well‐defined sizes and shapes represent a new family of model systems for establishing structure–function relationships in heterogeneous catalysis. Here in this study, we show that catalyst poisoning can be utilized as an efficient strategy for nanocrystals shape and composition control, as well as a way to tune the catalytic activity of catalysts. Lead species, a well‐known poison for noble‐metal catalysts, was investigated in the growth of Pd NCs. We discovered that Pb atoms can be incorporated into the lattice of Pd NCs and form Pd–Pb alloy NCs with tunable composition and crystal facets. As model catalysts, the alloy NCs with different compositions showed different selectivity in the semihydrogenation of phenylacetylene. Pd–Pb alloy NCs with better selectivity than that of the commercial Lindlar catalyst were discovered. This study exemplified that the poisoning effect in catalysis can be explored as efficient shape‐directing reagents in NC growth, and more importantly, as a strategy to tailor the performance of catalysts with high selectivity.     

Assessment of environmental contamination risk by Pt, Rh and Pd from automobile catalyst

The main active components of present-day car catalysts are the noble metals Pt, Pd and Rh, belonging to the platinum group elements (PGEs). It is recognized that these elements are being spread into the environment to an as-yet incompletely known extent, mainly due to surface abrasion of the catalyst during car operation. These new pollutants have motivated extensive research on PGE determination. Our work is planned to ascertain the health and ecosystem risks of these PGEs emitted through a series of interrelated objectives that address the pathway of these elements from the catalyst to the different environmental compartments. Combined studies of catalyst surface abrasion and exhaust fumes analysis, the monitoring of Pt, Pd and Rh in airborne particles and road dust sediments and bioaccumulation studies in aquatic organisms, plants and urine enable a realistic assessment of the risk that this release represents for man and environment. In this work some previous results are presented.     

Spatial distribution of major and trace elements in bladder and kidney stones

The spatial distribution of major and trace elements has been studied in a range of human kidney and bladder stones with well documented histories to understand their initiation and formation. The stones were cut in half using a clean diamond saw and further cleaned, to remove surface contamination, in an ultrasonic bath. The cut surfaces were analyzed using laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). The spatial distribution of Li, B, Mg, Al, P, Ca, Cr, Mn, Zn, Rb, Sr, Ba and Pb has been determined across the width of each stone.     

Enhanced methane decomposition over transition metal-based tri-metallic catalysts for the production of COx free hydrogen

In this study, COx-free hydrogen production via methane decomposition was studied over Cu–Zn-promoted tri-metallic Ni–Co–Al catalysts. The catalysts have been prepared by the constant pH co-precipitation method, and the nominal Ni metal loading was fixed at 50 wt % along with other metals at 10 wt% each. The catalyst activity for methane decomposition reaction was examined in a reactor between 400 °C and 700 °C and at atmospheric pressure. Different techniques such as N₂-physisorption, X-ray diffraction, H₂-TPR SEM, TEM, ICP-MS, TGA, and Raman spectroscopy were applied to characterize the catalysts. The relation between the catalyst composition and their catalytic activity has been investigated. The controlled synthesis has resulted in a series of catalysts with a high surface area. Ni–Co–Cu–Zn–Al was the most active and productive catalyst. Various characterizations indicate that the promotional effects of Cu–Zn interaction were the critical factor in catalysts' activity and stability. Ni–Co–Cu–Zn catalyst gave the highest methane conversion of 85% at 700 °C. Zn addition improves the stability of the catalyst by retaining the active metal size during the decomposition reaction. The catalyst was active for 80 h of stability study. The rapid deactivation of the Ni–Co catalyst was due to the sintering of the catalyst at 650 °C. Moreover, carbon species accumulated during the methane decomposition reaction depend on the catalysts' composition. Zn promotes the growth of reasonably long and thin carbon nanotubes, whereas the diameter of carbon nanotubes on unpromoted catalysts was large.     

广州市孕妇头发微量元素含量测定

测定了286例不同孕周孕妇头发锌、铁、铜、钙、锰、铅含量,并进行了比较分析。结果表明,孕期上述元素的异常率分别为：40．21％、37．76％、15．04％、45．46％、19．58％、27．97％。不同孕周变化各有差异,以孕中期变化最为明显（除铜和锰外,P＜0．01）。提示妊娠期妇女有益微量元素缺乏的现象是很普遍的,妊娠中晚期事理调整膳食结构和营养物质的补充是必要的。     

Monitoring of the exposure to platinum-group elements for two Italian population groups through urine analysis

It is well recognized that automobile catalytic converters are the main source of Pd, Pt and Rh (also called platinum-group elements (PGEs)) in an urban atmosphere. Over recent years, urinary biomonitoring of PGEs has gained considerable importance in assessing the individual human exposure to these elements. This paper reports the concentration ranges of PGEs in the urine of 257 Italian subjects, aged between 23 and 88 years. Subjects were selected on the basis of standardized criteria in two different Italian cities, so as to represent a small urban area surrounded by an essentially rural environment and characterized by low automobile-traffic density (Foligno) and a large urban area with almost constant high-traffic conditions (Rome). The determination of PGEs was performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) after 1:4 (v/v) dilution of the samples. The 5th and 95th percentiles for PGEs in urine of subjects living in Foligno were the following (in ng l⁻¹): Pd 1.99-17.2, Pt 0.24-3.08 and Rh 0.53-14.8. The 5th and 95th percentiles in the urine of subjects from the area of Rome were (in ng l⁻¹): Pd 0.71-17.0, Pt 0.49-8.13 and Rh 4.10-38.6. Platinum and Rh median concentration values showed large and significant differences (P<0.0001) between the two urban settings considered (0.52 and 3.50 ng l⁻¹ for Pt and Rh in Foligno, respectively, and 1.70 and 12.85 ng l⁻¹ for Pt and Rh in Rome, respectively). On the other hand, no striking differences were found in the Pd concentration (median value of 6.02 ng l⁻¹ in Foligno versus 7.79 ng l⁻¹ in Rome). The sex variable correlates only with Pd concentration (P=0.05), pointing out that in males concentrations are higher than in females.     

Concentrations of some elements in the coastal sea sediments: Bays with marinas

Summary Surface sediments and sediment cores from two bays in the Adriatic sea (Punat Bay and Soline Bay, Croatia) have been analyzed for a number of elements, in particular: Ti, V, Mn, Fe, Cu, Zn, As and Pb, by using XRF. Maps of elemental distribution in surface sediments show increased concentrations for some elements present in antifouling paints (Cu, Zn, Pb) near the service areas in the villages or marinas. Core profiles for these elements were used to evaluate the environmental impact of newly constructed marinas. Source partition indicates the influence of other sources located in near by villages. The critical factor in these considerations was shown to be water exchange with the open sea.     

中药驱铅对儿童血微量元素影响的研究

为探讨中药驱铅对儿童血Pb及微量元素Zn、Cu、Fe、Ca、Mn水平的影响 ,检测了 68例儿童铅中毒患儿服用中药驱铅前后的血Pb及微量元素Zn、Cu、Fe、Ca、Mn水平。结果显示 ,服药后患儿的血Pb明显低于服药前 ,差异有非常显著性 (P <0 0 1 ) ;血Zn水平明显高于服药前 ,差异有显著性 (P <0 0 5 ) ;铅中毒程度越轻 ,驱铅效果越明显 (P <0 0 1 ) ;血微量元素Fe、Cu、Ca、Mn水平无明显差异 (P >0 0 5 )。提示中药对儿童早期铅中毒的驱铅效果好 ,不存在微量元素失衡     

The volatilization of trace elements during oxidative pyrolysis of a coal from an endemic arsenosis area in southwest Guizhou,China

Household coal combustion has caused endemic poisoning in southwest Guizhou Province of China. The mineralogy, geochemistry and mode of occurrence of trace elements (TEs) of coal from this area were examined, and oxidative pyrolysis experiments of the coal were conducted in a box resistance reactor at 300–1200 °C to evaluate the volatilization of trace elements. In coal, As, Sb, Pb, Zn, W, Mo, and Cr are highly enriched when compared to both the world coal and Chinese coal. Cadmium, Sr, and Ba are all slightly higher than the average value for Chinese coal. The volatility of trace elements exhibits a close correlation with the mode of element occurrence. The considerable volatilization of As, Sb, Pb, Zn, Cd and Cr below 450 °C is thought to be related to the organic form of these elements. In the temperature range of 450–1200 °C, the volatility of all trace elements except As increases slowly with temperature because these elements are highly associated with silicates. Among the hazardous trace elements, As is the most volatile, and Sb, Pb, Zn, Cd and Cr are moderately volatile. Arsenic exhibits a uniquely high release at 900–1000 °C, which could be attributed to the high proportion of As association with sulfide. Because TEs are primarily inorganically-associated, the volatilization of TEs is not comparable to the loss of coal weight during pyrolysis. At high temperatures, a significantly low coal weight loss can result in a significant volatility of TEs.     

Multi-elemental characterization of tunnel and road dusts in Houston,Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g⁻¹ respectively in tunnel dusts while they varied between 6 and 8 ng g⁻¹, 10 and 88 ng g⁻¹ and 35 and 131 ng g⁻¹ in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling.     

TXRF analysis of aged three way catalysts

A methodology for the quantitative analysis of the elements present in car exhaust catalysts by TXRF is described. Some of the most relevant catalytic components (Zr, Rh, Pd) and contaminant elements (P, Pb, Zn, Pt, Ca and Ni) on car Three Way Catalysts were quantified during vehicle aging. The study was conducted along the main axis of a Ford Focus 1.6i catalytic cartridge, aiming to obtain the axial profile of the elements retained or eliminated after more than 59,000 km. The analysis of a fresh Three Way Catalysts (0 km) was also conducted for comparative purposes. The existence of a strong differences for elemental concentration in the interphase between the two blocks of the catalytic cartridge has been quantitatively measured for first time. In addition, the behaviour of the contaminant absorption capacity of both catalytic blocks has been obtained. Finally, the loss of the contaminant elements Pb and Zn to the environment has been proven.