Kinds Of Hydrocarbons Research Articles

Are floating treatment wetlands more suitable for retrofitting highway runoff basins than vertical-flow treatment wetlands?

Highway runoffs introduce numerous traffic-related pollutants – such as heavy metals, suspended solids and different kinds of hydrocarbons – into surface waters, thus endangering environmental health. In Germany, sedimentation basins with oil retention baffles are mandatory for the treatment of highway runoff in water protection areas. If the distance to the groundwater table is too low, further treatment with event-loaded vertical-flow treatment wetlands (VFWs) is required. In this study, we evaluated if retrofitting of stormwater retention basins to floating treatment wetlands (FTWs) can serve as an alternative to post-treatment VFWs and if native plant species could adapt to the oxygen-deprived salt-enriched environment. Two such basins with two hydraulically separated parallel chambers each near the municipality of Cologne were equipped with floating mats on one chamber, while the other one served as control. One location additionally had hydraulically separated post-treatment VFWs, allowing for a comparison with the treatment efficiency of the FTW. The removal of chloride, sulfate, suspended solids (total and < 63 μm), nutrients, metals, petroleum derived hydrocarbons and polycyclic aromatic hydrocarbons (PDH and PAH) was examined in 54 events over a period of two years. As a result, it was found that plants can create an intense root network despite hostile conditions in the basins. For the target parameters (TSS63, PAH and PDH), the removal efficiency of the stormwater retention basin was already sufficient. For metals and ammonium nitrogen, the VFWs proved to be more efficient, whereas for nitrate nitrogen, this was the case for FTWs. None of the treatment systems proved effective against reducing chloride concentration from deicing salts.

Role Played by Oil Emplacement in Controlling Pore Network Evolution of Tight Sandstones

Whether oil emplacement and diagenetic sequences provoke, deteriorate, or have no effect on pore network evolution, as implied by recent tests and theoretical analysis, are critical factors in forecasting hydrocarbon exploration and development potentials. Therefore, a systematic investigation on the effect of oil emplacement of tight sandstones is conducted to study the importance of this behavior on the pore evolution path. This study evaluated the role played by oil emplacement and diagenesis in the pore network evolution of Upper Triassic tight sandstones in the Ordos Basin. To help provide a comprehensive understanding, we have used a multidisciplinary method including physical properties, casting thin section, scanning electron microscope, X-ray diffraction, fluorometric, and inclusion analysis. The results demonstrate that the sandstones could be divided into four groups based on new criteria: calcareous sandstone, high soft component sandstone, low soft component sandstone with continual oil emplacement, and low soft component sandstone with intermittent oil emplacement. The physical properties of those types of sandstones were gradually reduced. Quartz cement captured hydrocarbon, carbonate captured hydrocarbon, free hydrocarbon, and adsorbed hydrocarbon were the four main kinds of hydrocarbons. The maturity of those sandstones was decreased progressively, indicating that the formation time of those hydrocarbons was favorable to maturity. Four stages of oil emplacement happened, and large-scale emplacement mainly occurred in the late Jurassic and early Craterous. The evidence demonstrated that tight sandstones’ high porosity could be attributed to positive diagenetic contributions with a complex interplay of chemical compaction, early formed clays, and large-scale oil emplacement. This work would provide new sights for a better understanding of the tight oil accumulation modes, and the findings could be applied in the hydrocarbon exploration and development field.

Lycopene ameliorates insulin resistance and increases muscle capillary density in aging via activation of SIRT1

Lycopene (Ly) is a kind of hydrocarbon, which belongs to the family of tetraterpene carotene and exists in red fruits and vegetables. The decrease of capillary density and blood flow with age is a significant reason for the increase of mortality and morbidity. Herein, our study aims to explore the effects of Ly (a bioactive food compound) on vascular aging in vitro and in vivo and its potential mechanisms. The cytological results showed that Ly could promote the proliferation of human umbilical vein endothelial cell (HUVECs) and enhance the ability of HUVECs to form capillary-like structures. Furthermore, the expression of SIRT1 in aged HUVECs was up-regulated. In vivo, aging rats showed signs of insulin resistance and blood vessel damage. Additionally, the capillary density and blood flow were reduced during the vascular aging process in both D‐gal‐induced and naturally aging muscle. However, when Ly was given, these conditions could be reversed. Simultaneously, the contents of ATP, lactic acid and pyruvic acid were determined, and it was found that Ly could promote angiogenesis by increasing the utilization rate of glucose and promoting energy metabolism. Finally, in the insulin resistance cell model, we knocked down the SIRT1 and administrated with Ly, and found that it couldn't restore insulin transdution. In conclusion, all the data in this study demonstrate that Ly could reactivate SIRT1 and improve insulin resistance, which was a reversible cause of vascular aging.

EGR gas composition effects on ignition delays in diesel combustion

This paper presents the effects on ignition delays of a range of exhaust gas compositions recirculated in the intake air. The ignition delays were measured in a single-cylinder diesel engine introducing a variety of hydrocarbons, nitrogen oxides (NOx), and carbon monoxide (CO) into the intake gas, and changing the concentrations of these components. The experimental results show that the ignition delay decreases with the NOx addition, NO2 promotes the ignition more than NO, and this effect is more pronounced at higher intake gas temperatures. The ignition delay decreases with HC addition under NOx rich conditions while there is little effect under low NOx conditions, and the ignition delay changes with the kinds of hydrocarbons. The CO has little effect on the ignition delay. With the aid of chemical reaction analysis, the mechanisms of these changes are elucidated.

The effects of surfactant/hydrocarbon interaction on enhanced surfactant interfacial activity in the water/hydrocarbon system

The phosphorus-based cationic surfactant dodecyltriphenylphosphonium bromide (C12TPB) was systematically evaluated for its interfacial activity by the interfacial tension (IFT) measurement and emulsification experiments. Interestingly, the C12TPB molecules exhibited the differential interfacial activity in the water/hydrocarbon systems, which was mainly dependent on the hydrocarbon structure. The C12TPB could largely reduce the water/toluene IFT to 4.11 × 10−2 mN/m, whereas the water/n-octane IFT was slightly decreased to 4.2 mN/m at the same C12TPB concentration (10,000 mg/L). Moreover, the C12TPB stabilized emulsion in the water/toluene system showed the preferable stability and the smaller emulsion droplet than that in the water/n-octane system. The control experiments used another three kinds of hydrocarbons (n-hexane, cyclohexane, benzene) and isobutanol demonstrated that the π-π stacking interaction between C12TPB and aromatic hydrocarbon molecules greatly enhanced the C12TPB interfacial activity. The interaction energy calculation and the molecular dynamics simulation were employed to further confirm the proposed mechanism.

Biosurfactant Production by Bacteria Isolated from Hydrocarbon-impacted soil

Advancement in biotechnology and its industrial application has led to increased demand for biological compounds of microbial origin. Such compounds are biosurfactant and their application in different sectors is increasing despite some challenges. In the present study, the ability of bacterial species growing in hydrocarbon impacted soil to produce biosurfactants was investigated with a view to isolate competent biosurfactant producers with desirable qualities for a large scale biosurfactant production. Soil samples contaminated with different kinds of hydrocarbon were collected from Mechanic workshop (MW) and Mai-kose (MK) area in Maiduguri Metropolis, Nigeria. Soil samples were cultured on nutrient agar and mineral salt agar by pour plate technique for enumeration of viable bacteria and isolation of oil utilising bacteria respectively. Samples from MW were observed to harbour fewer bacteria than MK area with 7.3 ×107 CFU/g and 4.0×108 CFU/g respectively. Fifteen bacterial species were isolated and identified to belong to the genus Pseudomonas using cultural, morphological and biochemical characteristics. The species were P. aeruginosa, P. citronellolis and P. mendocina with 66.7%, 26.6% and 6.6% rate of occurrence. A preliminary investigation for the isolates’ ability to produce biosurfactants using haemolysis and hydrocarbon degradation tests revealed that all the isolates were haemolytic on blood agar and can utilise vegetable oil at different magnitudes. Biosurfactant assay using broth culture supernatants showed that all the isolates were able to produce surfactants that collapsed oil drop within the interval of 10-20 min and Pseudomonas citronellolis WB4 was most efficient in this respect (t = 10 min). With regards to oil spreading assay, P. aeruginosa KB1 produced largest diameter (d) of 4.21 cm after 15 min compared to other species (dav. = 3.44cm average tav. = 13 min). After 24 hrs of emulsion formation, it was observed that P. aeruginosa WB5 (E24 = 70.45%) and P. citronellolis WB4 (E24 = 70.35%) have the highest emulsification indexes (range 70.45% - 43.75%). Therefore, all isolates in this study were biosurfactant producers with P. citronellolis WB4 being the most suitable candidate for large-scale biosurfactant production. Hence, further studies are recommended to harness its full potentials.

BIODEGRADATION OF PETROLEUM INDUSTRY OILY SLUDGE AND ITS APPLICATION IN LAND FARMING: A REVIEW

One of the foremost solid wastes produced by petrochemical industries is oily sludge. Oily sludge being a mixture of various kinds of hydrocarbons has been characterised as a hazardous waste by Environment Protection Act and Hazardous Wastes Handling Rules which contributes a lot in environmental pollution. Polycyclic aromatic hydrocarbons (PAHs), which are components of crude oily sludge, represent serious environmental concerns, as most of them are mutagenic, cytotoxic and carcinogenic. Several methods for degradation of oily sludge and other petroleum related contaminants have been discussed in literature. This review paper presents the most efficient process of remediating these contaminants from environment, i.e., biodegradation by microorganisms. It is attaining significance as an increasingly efficient and potentially inexpensive cleanup strategy. Its potential contribution as a countermeasure biotechnology for decontamination of oil polluted systems could be vast, as it also leads towards mineralisation of complex organic compounds to simple compounds enhancing soil organic contents. So it can be concluded that biodegradation strategy of petroleum oily sludge, even with some limitations, have proved to be one of the most cost effective and promising technology with potential application in land farming.

Temperature influence on the properties of carbon-encapsulated iron nanoparticles forming in pyrolysis of gaseous precursors

In the present study the carbon-encapsulated iron nanoparticles were synthesized by shock waves pyrolysis of the Fe(CO)5 vapor in the mixture with C2H2 or C6H6 diluted by argon. The iron nanoparticles were formed behind incident shock waves at the temperatures of 600–1200 K. The pyrolysis of hydrocarbons behind the reflected shock waves at the temperatures of 1100–2500 K resulted in carbon shell formation over iron nanoparticles. The mean particle sizes measured by transmission electron microscopy were found to be 3.5–5 nm and 7–10 nm for the samples formed in the mixtures with presence of acetylene and benzene correspondingly. The extinction measurements of condensed phase growth and laser-induced incandescence measurements of particle sizes were used as in-situ diagnostics. The dependences of particle volume fraction and final particle size on temperature of pyrolysis and kind of hydrocarbon are presented and discussed.

전통적인 유체역학 방법론과 CFD 결합을 통한 Fischer-Tropsch 고정층 반응기 내부 흐름의 체계적 모델링

Fischer-Tropsch 반응기 내 복잡한 반응과 흐름을 상세히 모델링하는 것은 CFD 분야에 있어 도전적 과제이다. Fischer-Tropsch 반응은 여러 가지 탄소수를 가진 탄화수소들을 만들어내는데, 탄화수소에는 무수히 많은 이성질체가 존재하는 이유로 모든 화학종에 대해서 각각의 반응속도식을 도출해 적용하는 것은 어렵다. 이의 극복을 위해 기존 연구들에서 사용된 반응속도식 모델링 방법론들을 분석한 뒤, 화학종별 상세한 반응속도식 적용을 위해 non-Anderson-Schulz-Flory 방법론을 선정하여 상세 모델링을 진행하였다. 또한 반응 특성상 다상 흐름 형태를 띠는데, 다상 흐름 모델링의 경우 상간의 간섭이나 분산상의 분포 및 유동 형태 등에 따라 적합한 모델링 방법론이 다르다. 그러나 기존 연구들에서는 타당성에 대한 논의나 근거 제시 없이 각양각색의 내부 흐름 모델링 방법론이 사용되고 있다. 실험을 통해 내부 흐름 형태를 관찰한 뒤 유동 형태에 따른 모델링을 진행하는 것이 최선이나, 자원 여건상 어려움이 있어, 본 연구에서는 전통적인 유체역학 이론에 근거해 내부 흐름 형태를 먼저 추론하고 Mixture 모델 방법론을 선정하여 체계적인 CFD 모델링을 진행함으로써, 사용된 방법론에 대한 근거를 마련하고자 하였다. 10가지 실험조건에서 진행한 실험 결과와 본 연구의 시뮬레이션 결과를 비교하였으며, 이를 통해 본 연구가 제안하는 체계적 모델링 방법론의 타당성을 입증하였다. Modeling for complex reacting flow in Fischer-Tropsch reactor is one of the challenges in the field of Computational Fluid Dynamics (CFD). It is hard to derive each and every reaction rate for all chemical species because Fisher-Tropsch reaction produces many kinds of hydrocarbons which include lots of isomers. To overcome this problem, after analyzing the existing methodologies for reaction rate modeling, non-Anderson-Schulz-Flory methodology is selected to model the detailed reaction rates. In addition, the inside flow has feature of multi-phase flow, and the methodologies for modeling multi-phase flow depend on the interference between the phases, distribution of the dispersed phase, flow pattern, etc. However, existing studies have used a variety of inside flow modeling methodologies with no basis or rationale for the feasibility. Modeling inside flow based on the experimental observation of the flow would be the best way, however, with limited resources we infer the probable regime of inside flow based on conventional fluid dynamics theory; select the appropriate methodology of Mixture model; and perform systematic CFD modeling. The model presented in this study is validated through comparisons between experimental data and simulation results for 10 experimental conditions.

Experimental investigation on flow condensation heat transfer of ethane in a horizontal tube

In recent years, due to the environmental problems of traditional chlorinated refrigerants, it has become an urgent task to search for suitable substitutes. Hydrocarbons, with zero ozone depleting potential, low global warming potential and high thermodynamic performance, are good alternative refrigerants in refrigerators and heat pump systems. In addition, hydrocarbons also the important parts of the natural gas. As one kind of hydrocarbons, ethane and its mixtures have been widely applied in the mixed refrigerant throttling refrigeration systems and recommended to be used in the cascade refrigeration systems to replace R13 and R503. As the heat transfer characteristics of ethane play important parts in the design of the heat exchangers in refrigeration cycles, the heat transfer coefficients during condensation should be well examined and analyzed. Although there are massive experimental studies of heat transfer on flow condensation of hydrocarbons in horizontal tubes, the published experimental investigations for ethane are rare. Therefore, it’s desirable to conduct an experimental investigation on condensation heat transfer of ethane in a horizontal tube and find suitable correlations. In this paper, condensation heat transfer of ethane was studied experimentally in a horizontal tube with inner diameter of 4 mm. The heat transfer test section was a copper plate (100 mm× 20 mm× 200 mm) embedded twelve four-wire PT100 platinum resistance thermometers. Using the assumption of two-dimensional heat conduction for the copper plate, both the wall temperature and heat flux could be obtained. The tests were carried out at saturation pressures from 1.01 MPa to 2.56 MPa for mass fluxes from 100 kg/(m2 s) to 257 kg/(m2 s) and vapor qualities from 0 to 0.8. The uncertainties for the heat transfer coefficient with a 95% confidence interval were less than 3.33% under the employed operation conditions. The effects of mass flux, vapor quality and saturation pressure on condensation heat transfer coefficient were examined and analyzed. Some conclusions can be drawn that (1) in relative high mass fluxes and vapor qualities, the condensation heat transfer coefficients increased with the increasing mass flux and vapor quality while decreased with the increasing saturation pressure; (2) in relative low mass fluxes and vapor qualities, the vapor quality, mass flux and saturation pressure had a little influence on condensation heat transfer coefficients. In addition, the experimental data were compared with nine well-known correlations of condensation heat transfer coefficient. The comparison results showed that Chato (1962) correlation and Wang et al. (2002) correlation relatively agreed well with the experimental data with the mean absolute relative deviations less than 35%. The other correlations showed larger predicted results than the experimental data with the mean absolute relative deviations more than 55%. And the Chato correlation and Wang et al. correlation were both in good agreement with the relative low heat transfer coefficients rather than the relative high heat transfer coefficients.

Comprehensive Analysis of Electrochemical and Structural-Dynamic Properties of Bitumnious Insulating Materials

At the current stage the strategic trend of development of the oil and gas industry is increase in the oil conversation depth with the use of relatively new approaches and methods of mining, treatment, transporting and processing of different kinds of hydrocarbons. Along with that, implementation of new processing techniques, improvement of the production performance and quality of the output products, intensification and reconstruction of the existing oil and gas plants depend not only on the structural materials used but also on the right choice of anti-corrosive materials for protection thereof. According to the existing ideas of the most important factors determining anti-corrosive properties of bituminous insulating materials is mechanical insulation of the material from the aggressive media. Since the insulating film consists of the areas of different density with numerous micropores then by the coating contact with water or electrolyte solutions liquid penetration through the film (diffusion) as well as moisture adsorption by active centers of the film binder (swelling) take place. The criterion of insulating capacity is high effective resistance (minor permeability), low capacity (minor swelling) and slow change in the behavior in the time domain 1-3 . No less important factor determining the protective action of coatings is film adhesion ensuring not only film adhesion to the material but also preventing appearance of a new phase on the at the metal-film border. The film adhesion strength is affected by the internal stresses arising during the process of coating formation and relaxation processes. In order to protect material from corrosion, special substances are introduced in the insulating material that is able either to change kinetics of electrode reactions determining the corrosive process or inhibit it.

Saturated hydrocarbon content in olive fruits and crude olive pomace oils

ABSTRACTOlive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amounts of a complex mixture of paraffins, unresolved by gas chromatography (UCM – unresolved complex mixture), have been found in cuticle, stone (woody shell and seed), olive leaves, and talc used as an aid to olive oil extraction. The amounts of both kinds of hydrocarbons are related to the olive cultivar and are transferred to oils in a proportion depending on the oil-obtaining process (centrifugation or solvent extraction). In olive oil obtained by centrifugation, only n-alkanes were detected. However, in olive oil extracted by second centrifugation, small amounts of UCM paraffins were detected together with the n-alkanes. Olive pomace oils showed a very variable content of both types of hydrocarbons according to the different obtaining process, such as double centrifugation, solvent extraction or centrifugation followed by solvent extraction. ‘White mineral oil’ used in oil extraction machinery is the source of the high concentrations of UCM paraffins found in some olive and olive pomace oils. In the case of second centrifugation olive oil, a maximum limit of 50 mg kg−1 of UCM is suggested, whereas in the case of crude olive pomace oil, it amounts to 250 mg kg−1 plus an additional minimum of 1.0 for the n-alkanes/UCM ratio.

Thermal decomposition of alkane hydrocarbons inside a porous Ni anode for fuel supply of direct carbon fuel cell: Effects of morphology and crystallinity of carbon

This study improved the physical contact between anode and fuel in a direct carbon fuel cell (DCFC) by directly generating carbon in a porous Ni anode through thermal decomposition of three kinds of hydrocarbons (CH4, C2H6, C3H8). From electron microscope observations of the carbon particles generated from each hydrocarbon, carbon spheres (CS), carbon nanotubes (CNT) and carbon nanofibers (CNF) were identified with increasing carbon number. Raman scattering analysis was performed to determine the crystallinity of the carbon samples. As a result, the carbon samples (CS, CNT, and CNF) produced from CH4, C2H6 and C3H8 were found to be less crystalline and more flexible with increasing the carbon number. DCFC performance was measured at 700 °C for the anode fueled with the same mass of the carbon sample. It was found that the 1-dimensional CNT and CNF were more active to produce 148% and 210% times higher power density than the CS. The difference was partly attributed to the finding that the less-crystalline CNT and CNF had much lower charge transfer resistances than the CS. A lifetime test found that the CNT and CNF, which are capable of transporting electrons for much longer periods, maintained the power density much longer, as compared to the CS which can lose their point contacts between the particles shortly at high current density.

Catalytic cracking of binary hydrocarbons of n-dodecane and iso-dodecane under supercritical conditions

The mutual effect between different kinds of hydrocarbons would influence supercritical catalytic cracking behavior of jet fuel, and thus may affect the chemical heat sink. Highly branched iso-dodecane (mainly 2,2,4,6,6-pentamethylheptane, PMH) and n-dodecane were chosen as model hydrocarbons. The cracking of the binary system with different iso/n-dodecane ratios was conducted over HZSM-5 zeolite under supercritical conditions (673K, 4.0MPa). The results show that the cracking of n-dodecane in binary mixture is first inhibited but then accelerated with the increase of concentration of PMH, while the cracking of PMH was hardly effected. Limited by the inertness of PMH, total conversion of binary mixture is obviously lower than pure n-dodecane.

A Smart Sensor System for Detecting Hydrocarbon Volatile Organic Compounds in Sea Water

Hydrocarbons are among the most dangerous pollutants for the marine environment. The creation of smart systems to detect hydrocarbon spills in the marine environment is often complex and involves many issues. This paper presents an innovative approach based on a sensor system capable of detecting volatile organic compounds (VOCs) produced by hydrocarbons. The system was composed of an array of photo ionization detectors, lodged in a flow chamber and arranged in radial symmetry, in order to receive the same amount of air flow. The air inlet was placed on the upper face of the chamber, while the air outlet was on the lower face. The sensor characterization at the laboratory bench was performed using different kinds of hydrocarbons, such as gasoline, diesel fuel, kerosene, and crude oil, and their response was acquired using a smart electronic system based on an Arduino™ electronic board. With this approach, it was possible to detect mild‐to‐high concentrations of VOCs with a portable, lightweight, smart system, placed in an autonomous underwater vehicle and in a moored buoy.

Chemical and process mineralogical characterizations of spent lithium-ion batteries: An approach by multi-analytical techniques

Mineral processing operation is a critical step in any recycling process to realize liberation, separation and concentration of the target parts. Developing effective recycling methods to recover all the valuable parts from spent lithium-ion batteries is in great necessity. The aim of this study is to carefully undertake chemical and process mineralogical characterizations of spent lithium-ion batteries by coupling several analytical techniques to provide basic information for the researches on effective mechanical crushing and separation methods in recycling process. The results show that the grade of Co, Cu and Al is fairly high in spent lithium ion batteries and up to 17.62wt.%, 7.17wt.% and 21.60wt.%. Spent lithium-ion batteries have good selective crushing property, the crushed products could be divided into three parts, they are Al-enriched fraction (+2mm), Cu and Al-enriched fraction (−2+0.25mm) and Co and graphite-enriched fraction (−0.25mm). The mineral phase and chemical state analysis reveal the electrode materials recovered from −0.25mm size fraction keep the original crystal forms and chemical states in lithium-ion batteries, but the surface of the powders has been coated by a certain kind of hydrocarbon. Based on these results a flowsheet to recycle spent LiBs is proposed.

Structural Changes of Ni/YSZ Cermet for Solid Oxide Fuel Cells in Hydrocarbon Gas Containing Atmospheres

Macroscopic and microscopic structural changes of Ni/YSZ cermets in CH4, C2H6, and C3H8 containing atmosphere at 1073 K were evaluated by dilatometry and SEM observation. Carbon deposition was observed in low-humidified hydrocarbon atmospheres, accompanying significant expansion of the cermet. SEM observation of the cross section revealed that carbon deposition took place preferentially near the surface and Ni particles seemed to be surrounded by the deposited carbon. The expansion due to carbon deposition did not depend on the kind of hydrocarbon but on the amount of supplied carbon. On the other hand, in high-humidified hydrocarbon atmospheres, e.g. S/C ≥ 1, no carbon deposition and expansion were observed.

Methane–benzene binary mixture destruction in a reverse flow catalytic reactor

An experimental study of methane–benzene binary mixture purification in a bench-scale reverse flow reactor is carried out. Results for catalytic oxidation of the two hydrocarbons with remarkably discrepant chemical properties show that autothermal catalytic combustion of very lean combustible concentration can be achieved with periodic feed reversal. Benzene is well removed, but methane conversion is relatively low and mainly determined by the thermal level of the reactor. If methane is added as auxiliary fuel to maintain autothermal operation when the volatile organic compound (VOC) concentration in the contaminated air is too low, an excess amount is needed. The influences of gas superficial velocity, cycle period, and methane-to-benzene ratio are discussed. A mathematical model is developed and solved using a FORTRAN code, with good correspondence being observed between the two approaches. Results of experimental and numerical study indicate that, during catalytic oxidation of lean VOCs in reverse flow reactor, the mutual inhibition effect between different kinds of hydrocarbon can be neglected.

Aerosol Spectrometer for On-Line Measuring Diameters and Chemical Compositions of Volatile Organic Nanoparticles

We describe the design and performance of an aerosol spectrometer that simultaneously measures size-dependent concentration and chemical composition of volatile organic nanoparticles ranging from 10 to 470 nm. The spectrometer consists of a differential mobility analyzer (DMA) for size classification and a gas chromatography mass spectrometer (GC-MS) for composition analysis. The size-classified particles of two kinds of hydrocarbons, an aliphatic hydrocarbon and aromatic hydrocarbon, were directly introduced into the GC-MS after vaporization of the particles. The relation- ships between the concentrations of classified particles measured with an aerosol electrometer and the peak area of major fragment ions measured with the GC-MS were given to show the detection limit of our spectrometer. For a particle size of 330 nm, the lower detection limit of the spectrometer for particle concentration was approximately 7.5×10 4 particles cm -3 .

Surface Ionization Gas Detection on Platinum and Metal Oxide Surfaces

Surface ionization (SI) gas detection experiments have been performed on platinum (Pt) and metal oxide (MOX) films. The probability of surface ion emission varies with temperature in an Arrhenius-type manner. Among all hydrocarbons studied so far those with amine functional groups exhibited the lowest activation energies allowing detection in the ppm concentration range at emitter operation temperatures of about 400degC. All other kinds of hydrocarbons could not be detected under these same conditions, not even if their concentrations were as high as 1% or 2%. Under high-temperature conditions (~800degC), this kind of selectivity breaks down and solid-state SI emitters start to behave in a similar way as flame ionization detectors, allowing detection of a much wider range of hydrocarbon species. Emitter materials with surface morphologies in the nanometer range were found to form much more efficient ion emitters than emitters with smooth surfaces.