Carbon Nano-Flakes Produced by an Inductively Coupled Thermal Plasma System for Catalyst Applications

Carbon material was produced using an inductively coupled thermal plasma torch system of 35 kW and a conical shape reactor. The carbon nanopowders were obtained by plasma decomposition of methane at various flow rates and show a uniform microstructure throughout the reactor. The product has a crystalline graphitic structure, with a stacking of between 6 and 16 planes and a nano-flake morphology with particles dimensions of approximately 100 nm long, 50 nm wide and 5 nm thick. Nitrogen was also introduced in some synthesis experiments along with the methane precursor using flow rates of 0.1 and 0.2 slpm. The resulting product has the same structural properties and the nitrogen is incorporated into the graphitic structure through pyridinic type bonds.     

Synthesis of Carbon Nanohorns by Inductively Coupled Plasma

We demonstrate a new pathway for the synthesis of carbon nanohorns (CNHs) in a reactor by using inductively coupled plasma (ICP) and gaseous precursors. Thermal plasma synthesis allows the formation of different carbon allotropes such as carbon nanoflakes, hybrid forms of flakes and nanotubules, CNHs embryos, seed-like CNHs and onion-like polyhedral graphitic nanocapsules. In this study, pressure has the greatest impact on the selectivity of carbon nanostructures: pressure below 53.3 kPa favors the growth of carbon nanoflakes and higher pressures, 66.7 kPa and above, promotes the formation of CNHs. The ratio between methane and hydrogen as well as the global concentration of CH₄?+?H₂ inside the plasma flame are also crucial to the reaction. CNHs are formed preferentially by injection of a 1:2 ratio of H₂ to CH₄ at 82.7 kPa with a production rate of 20 g/h. The synthesis pathway is easily scalable and could be made continuous, which offers an interesting alternative compared to methods based on laser-, arc- or induction-based vaporization of graphite rods.

Graphical Abstract

     

Modeling Injection of Dense Liquid Sprays in Radio Frequency Inductively Coupled Plasmas

A spray model and a droplet collision model are implemented into a radio frequency inductively coupled plasma model. The discrete parcel technique combined with the stochastic Monte Carlo method is used to solve the spray equation and determine the outcomes of droplet collisions in dense sprays. Plasma--spray interactions are considered by adding source terms to the conservation equations of mass, momentum and energy of the plasma phase. Two types of the outcomes of water droplets collisions, coalescence and grazing, are predicted and compared to the experimental and analytical results. The agreement is quite good. The effects of droplet collisions on droplet size distribution of the spray and the spray evaporation are investigated. It is found that the droplet collisions can increase the average droplets size of the spray. For the mono-disperse spray, the collisions can lead to a delay on the spray evaporation. However, for the poly-disperse spray, the effect of droplet collisions on the spray evaporation could not be predicted before the calculation due to the randomness of droplet collisions.     

单颗粒计数策略定量检测癌胚抗原

该文提出了一种基于单颗粒电感耦合等离子体质谱(spICP-MS)的计数策略,用于癌胚抗原(CEA)的灵敏检测.该策略采用50 nm的金纳米颗粒(AuNPs)作为免疫识别和单颗粒计数的探针,以磁性纳米颗粒(MBs)作为免疫识别的捕获中心,基于夹心免疫反应,应用抗体标记的MBs捕获CEA和AuNPs探针.通过磁铁分离后,捕...     

Volatile Compounds Present in Carbon Blacks Produced by Thermal Plasmas

Carbon black nanopowders were produced using two thermal plasma processes based on DC, respectively ICP plasma torches. Although the produced particles were in the nanometer size range, the values obtained for the surface area of the particles using a Brunauer Emmett Teller technique were very small. This indicated the presence of contaminants in the experimental powders, as confirmed by Raman spectroscopy and Thermogravimetric Analysis. A thermal treatment process was developed in order to extract these volatile compounds, which were then identified using a Gas Chromatography—Mass Spectrometry method. The experimental powders were analyzed using Scanning and Transmission Electron Microscopy, X-Ray Diffraction and Raman Spectroscopy before and after the thermal treatment in order to determine the effect of the heat treatment on the powder structural properties.     

Compensation of Ca and Na Interference Effects in Axially and Radially Viewed Inductively Coupled Plasmas

The linear relationship between Ca and Na interferences and energy potentials for a wide range of atomic and ionic lines is used to compensate for variable intensity suppression in robust axially and radially viewed inductively coupled plasmas (ICPs). In the axial configuration, intensity attenuation varied from 0 to 40% in the presence of 0.5% Ca and Na. In the radially viewed ICP, interferences were smaller, varying from 5 to 15% for 0.5% Na and from 10 to 30% for 0.5% Ca. Signal attenuation was broadly a linear function of the energies of the spectral lines. These linear functions were estimated by using spectral lines covering the energy range from Sb I 206.833 (5.98 eV), Y II 371.209 and Sc II 361.384 (9.9 eV), Sc II 255.237 (11.42 eV), and Be II 313.042 (13.28 eV) nm. These functions were then used as variable internal standards to compensate for Ca, Na, and mixed Ca–Na matrix effects. Whereas analyte recoveries without compensation varied from about 40 to 90%, they varied mostly from 100 ± 5% when these functions were used. In the presence of Ca and Na, the Mg II 280.270/Mg I 285.213 nm intensity ratio decreased from about 12 for an aqueous solution to 9 at 1.5 kW. Such values confirm that the radially and axially viewed ICPs were robust.     

Etching of Silicon and Silicon Dioxide in Dense Low-Pressure Inductively Coupled Radiofrequency Discharge Fluorocarbon Plasmas

The results of a study on the selective etching of SiO₂ and Si in dense low-pressure (p < 1 Pa) inductively coupled radio-frequency discharge fluorocarbon (HF₃ and HF₃ + H₂) plasmas in a nonuniform magnetic field are reported. It was found that the selectivity of etching SiO₂/Si increased from 9 to 24 with the addition of hydrogen. In the etching of SiO₂ in a HF₃ + H₂ plasma under certain process conditions, groove ridges were formed at the bottom of the etched groove. The mechanisms of ridge formation and the role of ion bombardment in this process are discussed.     

Gold Nanoparticle Determination by Inductively Coupled Plasma-Mass Spectrometry,Anodic Stripping Voltammetry,and Flame Atomic Absorption Spectrophotometry

Gold Nanoparticles (AuNP) were measured by Inductively Coupled Plasma–Mass Spectrometry (ICP-MS), Anodic Stripping Voltammetry (SV), and flame Atomic Absorption Spectrophotometry (AAS). Experiments investigated the relationships between counts per second (ICP-MS), absorbance (AAS), or μA (SV) and Au concentrations in solutions bearing AuNP with sizes of 5, 15, and 50 nm. Similarly the impact of the solution matrix was assessed using deionized water, 1.0 M HNO₃, 1.0 M HCl (ICP-MS and AAS), and water containing the bacterium E. coli (～10⁶ organisms/mL) by all three types of instrumentation. Each instrument yielded linear calibration curves with a signal proportional to Au concentration over the concentration range 0.02 ppm to 1 ppm.The methods were all reliable when biomacromolecules or when organisms such as E.coli existed in the matrix. Comparing the limits of detection for the three methods, ICP-MS and SV were lower than AAS. Comparing cost, SV and AAS were less expensive than ICP-MS. Comparing time required for each measurement, AAS was shorter than ICP-MS and SV. In comparison of the interfering effects of E-coli, ICP-MS and AAS were less-affected, while SV was more affected. An intact E.coli or organism may be very absorptive on the electrode surface,which reduced the measured anodic currents in SV and also increased the standard deviations.     

纳米银的单颗粒-电感耦合等离子质谱法表征及其测定

建立单颗粒-电感耦合等离子体质谱法( SP-ICP-MS)测定稀溶液中纳米银颗粒粒度分布及纳米银颗粒数量浓度的方法。当停留时间为3 ms时,两个或多个纳米银颗粒同时进入检测器的可能性降至最低。采用5倍标准偏差迭代算法(5σ)区分纳米银颗粒信号和背景信号。采用SP-ICP-MS法测定3种商品级纳米银颗粒(30,50和100 nm)粒度分布和纳米颗粒浓度。结果表明：SP-ICP-MS法测定纳米银颗粒结果与纳米银的TEM值相近,可采用SP-ICP-MS法表征纳米银颗粒。本方法测定稀溶液中纳米银颗粒粒度检出限为25 nm,纳米银颗粒浓度检出限约为8×104个/L。将纳米银颗粒加入到自来水样品中并进行测定,获得相近的纳米银粒度分布及纳米颗粒浓度。本方法简单、快捷、灵敏度高,可为研究水环境中纳米银的风险评估提供可靠分析方法,并为饮用水中纳米银的监测提供分析技术。     

基于单颗粒电感耦合等离子体质谱法测定环境基质水样中纳米银颗粒

采用单颗粒电感耦合等离子体质谱法(SP-ICP-MS)同时测定环境水样中纳米银颗粒(AgNPs)的颗粒浓度、质量浓度和粒径分布,并考察了溶液的pH值、溶解性有机质(DOM)浓度以及离子强度等对AgNPs测定的影响。结果表明:SP-ICP-MS方法对60 nm AgNPs标准溶液的测定结果与标准值一致,准确性较好;pH值(5.0～7.0)、离子强度(≤1 mmol/L)和DOM浓度(≤30 mg/L)对测定结果影响较小;当溶液的pH值≤5.0或离子强度1 mmol/L时,AgNPs的颗粒浓度和粒径随pH值的下降或离子强度的增强而减小。采用SP-ICP-MS方法测定河水、染料废水、养殖废水3种水样中AgNPs的加标回收率分别为98.1%、83.3%和93.3%,表明该方法在合适的基质条件下可用于快速准确测定环境水样中AgNPs的颗粒浓度、质量浓度和粒径分布。     

电感耦合等离子体质谱法测定炭质页岩中的钨钼钪

炭质页岩中含有大量的炭化有机质,其中的钨钼在单一盐酸溶液中易水解,样品的完全消解及有效防止钨酸、钼酸的形成是准确测定炭质页岩中钨、钼和钪含量的关键。本文采用HCl-HF-HNO3-HClO4四酸体系消解,加盖形成蒸汽回流;采用酒石酸-盐酸体系浸取,有效防止钨酸、钼酸沉淀导致结果偏低问题。建立了电感耦合等离子体质谱法(ICP-MS)测定炭质页岩中的钨、钼、钪的分析方法。测定结果表明,各元素在0.01～200.0 μg/L 范围内线性关系良好,相关系数均在0.9999以上,方法检出限为0.011~0.045 μg/g。按照实验方法测定炭质页岩中的钨、钼、钪,结果的相对标准偏差(RSD,n=11)为0.77 %～2.6 %,加标回收率在94 %~107% 之间。     

电感耦合等离子体原子发射光谱法测定低碳高硫钢中铋的含量

采用电感耦合等离子体原子发射光谱法测定某低碳高硫钢中的铋含量。通过实验探讨了钢中基体元素及共存元素对铋元素分析谱线的光谱干扰情况,确定了合适的分析谱线和背景校正方法,铋元素的分析谱线为223．061nm。根据某低碳高硫钢中铋元素含量范围,合成系列标准溶液,建立工作曲线,工作曲线的线性范围为0．01％～0．50％,线性相关系数r=0．9998,方法检出限为0．00279％,测量结果的相对标准偏差小于2．7％,加标回收率为98．2％～101．2％。     

Three-Dimensional Two-Temperature Modeling of Ar Loop-Type Inductively Coupled Thermal Plasma for Surface Modification

In this paper, numerical calculations were made for Ar loop-type inductively coupled thermal plasma (loop-ICTP). The loop-ICTP was developed originally by the authors’ group for rapid surface modification of large areas. Loop-ICTP is sustained with a unique three-dimensional (3D) configuration inside a circular loop quartz tube and on the substrate. A 3D and two-temperature thermofluid thermal plasma model was adopted for this calculation. Mass, momentum, and energy conservation equations were solved using a Maxwell equation for vector potential, an electron energy transport equation, and Saha’s equation in the 3D space. Results indicate that Ar loop-ICTP can be sustained and formed in the loop tube and also on the substrate. Moreover, the heavy particle temperatures reaches 1800–2000 K, whereas the electron temperature is about 10,000 K. Loop size effects on the gas temperature and gas flow field were also investigated using the developed model. Results show that adoption of a larger loop tube can be expected to improve the plasma uniformity on the substrate when applied to rapid surface modification.

     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定纳米银抗菌产品中多种微量元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定4种纳米银抗菌产品中多种微量元素的分析方法。比较了湿法消解和微波消解这两种样品前处理方法对样品测定的影响,探讨了消除汞记忆效应的方法,并研究了待测元素的质谱干扰的消除。实验结果表明,采用Au(100μg/L)+HCl(2%)能较好地消除Hg的记忆效应。与湿法消解相比,微波消解可短时间消解样品并获得好的Hg回收率。在优化ICP-MS条件后,各元素线性相关系数均大于0.999。采用微波消解-ICP-MS法对样品进行加标回收,样品加标回收率在84.0%~109%,相对标准偏差在0.97%~13.2%。方法快速、简便,能够满足纳米银抗菌产品中微量元素的定量测定。     

超声辅助提取/单颗粒电感耦合等离子体质谱法测定防晒化妆品中的纳米二氧化钛

建立了超声辅助提取/单颗粒电感耦合等离子体质谱(SP-ICP-MS)测定防晒化妆品中纳米TiO_2的方法。考察了停留时间、纳米粒子数量及浓度等分析条件,确定了防晒化妆品中纳米TiO_2的最佳萃取条件以及测定方法,对比了不同萃取溶剂对防晒霜中纳米TiO_2的提取效果。结果表明,在采用0. 1%Tritonx-100(Tx-100)以及5%乙醇作为萃取剂超声辅助提取,测定停留时间为3 ms,待测样品中纳米颗粒的数量浓度低于4×10~7个/mL条件下,该法可准确测定防晒化妆品中的纳米TiO_2,对防晒化妆品中纳米TiO_2的数量浓度检出限(LOD_(conc))为1×10~4个/mL,纳米颗粒粒度检出限(LOD_(size))为35 nm。方法简单快捷、灵敏度高、准确性良好,可同时对防晒化妆品中TiO_2进行浓度测定及粒度分布表征。     

酶消解-单颗粒电感耦合等离子体质谱法测定农产品中纳米铂颗粒

铂纳米颗粒在汽车行业中被广泛用作汽车尾气催化剂。随着铂纳米颗粒在工业生产中的广泛应用,它在环境中广泛分布并可能从植物累积进入食物链中。因此,建立一种在农产品中的定量分析方法是至关重要的。以酶消解的前处理方法结合单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定农产品中纳米铂颗粒(PtNPs)粒径分布及颗粒数量浓度。通过优化前处理提取条件,当Macerozyme R-10酶为10 mg、柠檬酸缓冲溶液浓度为5 mmol/L、提取时间36 h时,农产品中PtNPs提取效果较高。PtNPs粒径检出限为20 nm,颗粒浓度检出限为5×10⁵particle/L,铂颗粒浓度回收率在(81±3)%～(91±4)%,加标后平均粒径(41±3)～(47±2) nm,与50 nm PtNPs标准溶液粒径接近。方法操作简单、检出限低、准确度高,适用于农产品中PtNPs定量分析,为客观评价农产品铂纳米毒性效应提供可靠的分析技术。     

电感耦合等离子体光谱和质谱法分析贻贝标准物质

采用电感耦合等离子体光谱和质谱法分析了贻贝标准物质,光谱法测定Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ｐ、Ａｌ、Ｆｅ、Ｚｎ、Ｍｎ和Ｓｒ,质谱法测定Ａｓ、Ｂ、Ｃｄ、Ｃｏ、Ｃｒ、ＣｕＧａ、Ｇｅ、Ｍｎ、Ｍｏ、Ｎｉ、Ｐｂ、Ｓｅ、Ｓｒ、Ｕ和Ｖ。在优化的工作条件下,测定了来自基体元素Ｋ、Ｎａ、Ｃａ、Ｐ、Ｃｌ的Ｃ的多原子离子＾３９Ｋ＾１６Ｏ、＾３９Ｋ２、＾４０Ａｒ＾２３Ｎａ、＾４３Ｃａ＾１６Ｏ、＾４２Ｃａ＾１６Ｏ、＾３１Ｐ＾１６