Trap Material Research Articles

Method development and validation for total mercury determination in coke oven gas combining a trap sampling method with CVAAS detection

Coke oven gas is one of the by-products of the coal coking process. It is used as a fuel in the coking plant, but also as a raw material in the chemical industry to produce methanol, syngas or environment-friendly, low-CO2 hydrogen fuel. Due to the reasons mentioned above, the knowledge of coke oven gas pollutants such as mercury is a key issue. To determine the mercury in the cleaned coke oven gas a trap sampling method combined with CVAAS mercury detection was developed, optimized and validated. In order to perform the sampling process the traps filled with activated carbon were used. The determination of mercury in the traps material was performed by means of an MA-2 mercury analyzer. During the optimization of the method one selected the trap material, sample volume and flow rate. The optimal volume of the coke oven gas sample was 3 dm3 and the flow rate was 18 dm3/h (per one trap). The developed method was validated according to the Eurachem recommendation and was applied to determine mercury in the clean coke oven gas. The coke oven gas sampling was performed in a coking plant in Poland. The average concentration of mercury in the clean coke oven gas was 3.2 ± 0.3 μg/m3N (k = 2) for n = 18.

Role of the process conditions on the sulphation and stability of a CuO/SBA-15 type SOx adsorbent in cycling operations

SOx abatement is one of the major challenges for the industry with regards to the more stringent European regulations. Despite their good performance, current DeSOx technologies are energy-intensive and produce waste. Flue gas desulphurisation using SOx adsorbents thus is a viable alternative. However, the development of such a technology is still hampered by the adsorbent short lifetime within the wide range of conditions prevailing at the exhaust of combustion engines. In this work, a CuO/SBA-15 adsorbent was assessed as a SOx trap material under different sulphation conditions (temperature from 350 °C to 450 °C, gas composition (SO2: 250, 450 and 450 ppm; O2: 150 vol%), GHSV from 18,000 to 110,000 h−1 and sulphation time). The SO2 adsorption capacity of the adsorbent was greatly impacted by the temperature: the higher the temperature, the better the performance. Indeed, the dynamic adsorption capacity is equal to 31 mgSO2/gads, 37 mgSO2/gads and 52 mgSO2/gads at 350 °C, 400 °C and 450 °C respectively. Conversely, no significant changes in the SO2 dynamic adsorption capacity were observed whatever the SO2 and O2 molar fractions in the adsorption gas stream. The GHSV appears as a very sensitive parameter since the higher this parameter, the worse the adsorbent performance (e.g. for GHSV of 25,000 h−1, Cads = 37 mgSO2/gads; for GHSV of 50,000 h−1, Cads = 19 mgSO2/gads). Stabilised SO2 adsorption capacities along 25 cycles were obtained by regenerating before the breakthrough. Under these conditions, no SO2 emission occurs during the adsorption step, which represents the major technology block faced in any multicycle adsorption-based process over time.

Studies on the up-take behaviour of nickel foam for the activated products from liquid sodium using instrumental neutron activation analysis (INAA)

In an operating fast reactor, without an occurrence of fuel pin failure, the activated corrosion products 54Mn and 60Co along with activation product 65Zn are of major concern causing MAN-REM problem during maintenance. Experiments were carried out towards the development of a single trap material to co-trap the above-mentioned radionuclides using nickel foam. The scavenging behaviour of the nickel foam under different experimental conditions were studied using Instrumental Neutron Activation Analysis and the results were found to be in good agreement with the results obtained using Atomic Absorption Spectroscopic Analysis technique also.

Long-term activity of a CuO/SBA-15 type SOx adsorbent: Impact of the regeneration step

Sulphur oxides (SOx) are a major air pollutant regulated by European legislations. To date, most efficient DeSOx technologies are energy-intensive and produce high amounts of waste. Thus CuO/SiO2 adsorbents represent a viable SOx trapping alternative. However, their large-scale development is hampered by the sintering of the active phase over multiple adsorption and regeneration cycles, leading to the progressive decrease in performance of the adsorbent. In this work, a CuO/SBA-15 adsorbent was assessed as a SOx trap material and different regenerations methods were evaluated with the aim to limit that sintering phenomenon and assure the conservation of SO2 adsorption performance over several adsorption and regeneration cycles. It was found that a regenerative treatment under 0.5 vol% of H2 in N2 can be carried out either at 300 °C or 400 °C, without any substantial loss of SO2 adsorption performance over 8 successive cycles. A diffusional-limited decomposition mechanism describes the different steps of the regeneration stage, especially the kinetics of the regeneration step that is governed by the H2 transport within the porosity. The SO2 adsorption process was not the main degradation path of the textural properties of the adsorbent but the latter are strongly affected by the thermal effect associated to the adsorption and regeneration cycling.

Vanadium contamination of FCC catalyst: Understanding the destruction and passivation mechanisms

Vanadium scavenging material comprising magnesium and yttrium oxides (Mg-Y-oxide) was prepared and evaluated for vanadium capture under simulated FCC regeneration conditions for typical FCC process. Vanadium trapping ability was measured using BET, XRD, FTIR, EDX coupled SEM and MAT. The results show that physiochemical properties, vanadium trapping and catalyst protection increase with amount of the trap material. SEM-EDX results confirm migration of vanadium as indicated by its presence in the passivator particle. Vanadium migrates within the catalyst particles by both inter and intra particles mechanisms. The XRD data further reveal high vanadium selectivity towards yttrium when passivator is incorporated after impregnation of vanadium, with the formation of crystalline yttrium vanadate (YVO4). Catalytic evaluation indicates improved activities of catalysts containing passivator which correlate with physiochemical parameters. In the passivation mechanism, mobile vanadic acid preferentially reacts more with Y2O3 in mixed metal oxide due to its higher activity (active sites), forming YVO4. These results therefore reveal that the passivator protects the catalyst by formation of immobile vanadate with mobile vanadic acid, thereby reducing hydrolysis of the catalyst framework and thus preserving important properties of the catalyst.

Optimizing Circulating Tumor Cells' Capture Efficiency of Magnetic Nanogels by Transferrin Decoration.

Magnetic nanogels (MNGs) are designed to have all the required features for their use as highly efficient trapping materials in the challenging task of selectively capturing circulating tumor cells (CTCs) from the bloodstream. Advantageously, the discrimination of CTCs from hematological cells, which is a key factor in the capturing process, can be optimized by finely tuning the polymers used to link the targeting moiety to the MNG. We describe herein the relationship between the capturing efficiency of CTCs with overexpressed transferrin receptors and the different strategies on the polymer used as linker to decorate these MNGs with transferrin (Tf). Heterobifunctional polyethylene glycol (PEG) linkers with different molecular weights were coupled to Tf in different ratios. Optimal values over 80% CTC capture efficiency were obtained when 3 PEG linkers with a length of 8 ethylene glycol (EG) units were used, which reveals the important role of the linker in the design of a CTC-sorting system.

Development of high velocity gas gun with a new trigger system-numerical analysis

In development of high performance armor vests, we need to carry out well controlled experiments using bullet speed of more than 900 m/sec. After reviewing trigger systems used for high velocity gas guns, this research intends to develop a new trigger system, which can realize precise and reproducible impact tests at impact velocity of more than 900 m/sec. A new trigger system developed here is called a projectile trap. A projectile trap is placed between a reservoir and a barrel. A projectile trap has two functions of a sealing disk and triggering. Polyamidimide is selected for the trap material and dimensions of the projectile trap are determined by numerical analysis for several levels of launching pressure to change the projectile velocity. Numerical analysis results show that projectile trap designed here can operate reasonably and stresses caused during launching operation are less than material strength. It means a projectile trap can be reused for the next shooting.

Chemical trapping of gaseous H2S at high and low partial pressures by an iron complex immobilized inside the montmorillonite interlayer

A stable hybrid material (Mt-Fe(III)Phen) formed by intercalation of the μ-oxo Fe(III)-phenanthroline complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]4+ (Fe(III)Phen) in montmorillonite (Mt) is able to immobilize H2S in gaseous phase with high efficiency even at extremely low pressures. DR UV–vis and I.R. spectroscopies, elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry, and X-ray absorption spectroscopy show that the material has high adsorption capacity, performs fast H2S trapping and is long-lasting. Moreover, even extremely low levels of H2S can be removed easily and quickly from gaseous phase using a suitable amount of the trapping material. The immobilization mechanism likely involves a redox reaction between iron (III) and one S2− ion, followed by the binding of a second S2− ion to the metal centre. The process takes place at room temperature, is reversible for several cycles, and does not require pre-treatment of neither gaseous H2S nor the adsorbent material. Therefore, this modified montmorillonite is a promising material to get rid of H2S in processes of environmental interest and to obtain gaseous (and gasifiable) high quality hydrocarbons in fuels refineries.

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Seafloor sediment resuspension events of different scales and magnitudes and the resulting deep (>1,000 m) benthic nepheloid layers were investigated in the northern Gulf of Mexico during Fall 2012 to Summer 2013. Time-series data of size-specific in-situ settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras), particle size distributions (profiling camera), currents (various current meters) and stacked time-series flux data (sediment traps) were combined to recognize resuspension events ranging from small-scale local, to small-scale far-field to hurricane-scale. One small-scale local resuspension event caused by inertial currents was identified based on local high current speeds (>10 cm s–1) and trap data. Low POC content combined with high lithogenic silica flux at 30 m above bottom (mab) compared to the flux at 120 mab, suggested local resuspension reaching 30 mab, but not 120 mab. Another similar event was detected by the changes in particle size distribution and settling speeds of particles in the benthic nepheloid layer. Flux data indicated two other small-scale events, which occurred at some distance, rather than locally. Inertia-driven resuspension of material in shallower areas surrounding the traps presumably transported this material downslope leaving a resuspension signal at 120 mab, but not at 30 mab. The passage of hurricane Isaac left a larger scale resuspension event that lasted a few days and was recorded in both traps. Although hurricanes cause large-scale events readily observable in sediment trap samples, resuspension events small in temporal and spatial scale are not easily recognizable in trapped material as they tend to provide less material and become part of the background signal in the long-term averaged trap samples. We suggest that these small-scale resuspension events, mostly unnoticed in conventional time-series sampling, play an important role in the redistribution and ultimate fate of sediment distribution on the seafloor.

Charge carrier trapping processes in lanthanide doped LaPO4, GdPO4, YPO4, and LuPO4

Various methods for deliberate design of electron and hole trapping materials were explored with a study on double lanthanide doped rare earth ortho phosphates.

NO oxidation on Fe- and Cu-zeolites mixed with BaO/Al2O3: Free oxidation regime and relevance for the NH3-SCR chemistry at low temperature

Oxidative activation of NO is commonly regarded as a key step in the low-temperature mechanism of Standard SCR on metal-promoted zeolite catalysts for NH3-SCR of NOx. In the present work, we systematically investigate the dynamics of NO oxidation as well as the reactivity of NO+NO2 with adsorbed and gas-phase NH3 on Fe-ZSM-5 and Cu-CHA catalysts, using chemical trapping techniques. The approach is based on physically mixing the metal promoted zeolite catalyst with a NOx trap material, i.e. BaO/Al2O3. We show that in these combined systems, as long as NOx storage sites are available, the initial rate of NO oxidative activation is substantially higher than over the metal promoted zeolite alone, as measured in conventional steady-state activity tests for NO oxidation to NO2. Similar dynamics with enhanced initial NO conversions are observed also in the case of metal promoted zeolite catalysts with preadsorbed NH3, suggesting a close analogy between the role of BaO in the chemical trapping runs and the role of adsorbed NH3 in Standard SCR conditions, both species removing effectively the NO oxidation products from the gas phase and therefore preventing their inhibitory action. These novel findings are relevant to estimate correctly the intrinsic kinetics of the NO oxidative activation over metal-promoted zeolite SCR catalysts, and may help to explain the so far unresolved divergence between the rate of NO oxidation to NO2 and the rate of the Standard SCR reaction. We show, in fact, that the rate of uninhibited NO oxidation is able to sustain the Standard SCR activity over both Fe- and Cu-zeolite catalysts.

Austrosciara Schmitz & Mjöberg, 1924, a senior synonym of CtenosciaraTuomikoski, 1960 (Diptera: Sciaridae) and the description of a new brachypterous species in the genus.

Three species of wing-reduced Sciaridae, obtained from pitfall trap material collected from Nothofagus forests in Victoria, Australia, were examined. The females, which were all very similar, do not belong to any of the wing-reduced sciarid genera known to us so far. They instead appear to be females of the genus Austrosciara Schmitz & Mjöberg, 1924, according to the original description and illustration, and one of the species appears to be conspecific with Austrosciara termitophila Schmitz & Mjöberg. The shape of the male hypopygium, as well as the tibial organ of this species in both sexes show typical features of species previously classified as Ctenosciara Tuomikoski, 1960. The genus Ctenosciara Tuomikoski, 1960 n. syn. has therefore to be considered a junior synonym of Austrosciara Schmitz & Mjöberg. A further species described as Austrosciara pedibusa sp. n., based on female specimens, is typically characterized by a deep sensory pit on the basal segment of the palpus. The female of a third species, listed as Austrosciara sp., is illustrated as well.

Diagenesis of amino compounds in water column and sediment of Lake Baikal

The diagenesis of amino compounds in Lake Baikal was studied in sediment trap material (18 different water depths between 50–1350m) and underlying sediment (0–40 cm). Total hydrolysable amino acids (THAA), the amino acid (AA) composition including d- and l-enantiomers and amino sugars were analyzed. The study provides information on early diagenesis (<1 year) of settling material as well as on longer-term diagenesis (up to 600 years) occurring in the sediment. AA based diagenetic indicators were successfully applied to reveal changes at the different diagenetic stages. With increasing water and sediment depth, consistent decreases were found in: (1) the contributions of AA to total organic carbon (%TAAC, from 20 to 7%) and total nitrogen (%TAAN, from 54 to 20%); (2) the ratios of protein AA and their respective non-protein degradation products (aspartic acid:β-alanine, from 15 to 2; glutamic acid:γ-aminobutyric acid, from 28 to 2; arginine:ornithine, from 19 to 2); and (3) the AA based degradation index (from 0.7 to −1.1). There was multiple evidence that diagenesis went along with a progressive transformation of phytoplankton and zooplankton into bacterial organic material. Glycine, which is enriched in bacterial peptidoglycan, increased in relative abundance and bacteria-derived d-AA preferentially accumulated over proteinaceous l-AA. Molar ratios of glucosamine and galactosamine decreased towards a ratio of 1.0 ± 0.1 in the sediment, similar to ratios previously reported for detrital marine organic material. The general pattern of amino compound diagenesis in Lake Baikal resembles the pattern observed in marine systems, indicating a universal character of the processes controlling diagenesis in aquatic environments.

Femtosecond Laser Trapping Dynamics of Nanoparticles: A Single Transient Assembly Formation Leading to Their Directional Ejection

We investigated femtosecond laser trapping dynamics of silica nanoparticles with different hydrophobic surface properties. We demonstrated that the hydrophobic surface on the silica nanoparticles facilitates mutual association of the nanoparticles in the optical trapping site. Such association of optically trapped nanoparticles is a prerequisite to induce their directional ejection away from the trapping site. The directional ejection of the optically trapped nanoparticles is most probably due to asymmetric three-dimensional ejecting forces generated by the electromagnetic interaction between transient assembly in the focal spot and the incident pulses. These findings provide important insights into the directional ejection of nanoparticles from the trapping site in the femtosecond laser trapping, and this physicochemical phenomenon is controlled by both the trapping laser and material properties.

Effects of pin thread on the in-process material flow behavior during friction stir welding: A computational fluid dynamics study

Abstract Pin thread is one of the most common geometrical features for the friction stir welding (FSW) tools. The main purpose of employing the pin thread is to improve the in-process material flow behaviors during FSW. However, it has not been fully understood how exactly the pin thread influences the material flow because of the lack of in-process observation. In this study, we aim to analyze the effect of pin thread on the in-process material flow during FSW of an Al-Mg-Zn alloy by using numerical simulation based on computational fluid dynamics (CFD). In our numerical simulation, the transient rotation of the threaded pin is implemented explicitly via fully transient control of the zone motion, and the mechanical interaction at the tool-workpiece interface is considered via the recent developed shear-stress-based frictional boundary condition. The numerical simulation has been validated by the experimental measured temperatures at 8 different locations, the distribution of marker materials and the geometry of deformation zone in the weld. Based on the numerical simulation results, three effects of the pin thread on the material flow have been elucidated. First, accelerated flow velocity and enhanced strain rate is induced owing to the use of the pin thread, which is attributed to the fact that the interfacial sticking is preferable inside the thread groove opening. Second, the pin thread has an effect to trap material in the high-velocity zone inside the thread groove opening, which causes a many-circle flow pattern around the threaded pin. Third, the pin thread contributes to a vertical pressure gradient, which is important for the in-process material transfer from the top to the bottom. The approaches and concepts in this study can be applied for further fundamental investigation of FSW and the computer aided design of the welding tools.

Calcification depths of planktonic foraminifera from the southwestern Atlantic derived from oxygen isotope analyses of sediment trap material

Abstract We present a multi-year record of shell fluxes and δ18O of six planktonic foraminifera species (Globigerinoides ruber pink, Globigerinoides ruber white, Trilobatus sacculifer, Orbulina universa, Neogloboquadrina dutertrei, Globorotalia menardii) from sediment traps located in the southwestern Atlantic. Among the six species, only the fluxes of G. ruber white and N. dutertrei exhibit a significant seasonal component, with G. ruber white showing a single flux peak in austral summer, and N. dutertrei exhibiting two flux peaks in spring and autumn. To estimate calcification depths of the studied species, we then compare their measured δ18O to vertical δ18O profiles predicted for each collection time from in-situ temperature profiles and climatological salinity profiles. For the majority of the cases, the measured δ18O could be accounted for by in-situ calcification, assuming species-specific temperature-δ18O calibrations. The resulting estimates of the calcification depth imply that each species exhibits a characteristic typical mean calcification depth. The estimated calcification depths for N. dutertrei (mode 60–70 m) and G. menardii (mode 70–80 m) appear to track the depth of the thermocline in the region, whereas the calcification depths of the remaining four species correspond to conditions in the mixed layer. Among the apparent mixed-layer calcifiers, G. ruber pink and white appeared to calcify consistently shallower (mode 30–40 m) while T. sacculifer calcified deeper (mode 50–60 m). Because of the low flux seasonality, the observed oxygen isotope offsets among the species are similar to the flux-weighted mean annual δ18O offsets, indicating that isotopic offsets among the species in sediment samples are mainly due to different calcification depths. Since the habitat offsets among the species are consistent across seasons, δ18O in sedimentary shells can be used to track conditions in different parts of the water column and the difference in the oxygen-isotope composition between surface species (best represented by G. ruber pink) and thermocline species (best represented by N. dutertrei) can be used as a proxy for stratification in the southwestern Atlantic.

The Proton Trap Technology—Toward High Potential Quinone‐Based Organic Energy Storage

AbstractAn organic cathode material based on a copolymer of poly(3,4‐ethylenedioxythiophene) containing pyridine and hydroquinone functionalities is described as a proton trap technology. Utilizing the quinone to hydroquinone redox conversion, this technology leads to electrode materials compatible with lithium and sodium cycling chemistries. These materials have high inherent potentials that in combination with lithium give a reversible output voltage of above 3.5 V (vs Li0/+) without relying on lithiation of the material, something that is not showed for quinones previously. Key to success stems from coupling an intrapolymeric proton transfer, realized by an incorporated pyridine proton donor/acceptor functionality, with the hydroquinone redox reactions. Trapping of protons in the cathode material effectively decouples the quinone redox chemistry from the cycling chemistry of the anode, which makes the material insensitive to the nature of the electrolyte cation and hence compatible with several anode materials. Furthermore, the conducting polymer backbone allows assembly without any additives for electronic conductivity. The concept is demonstrated by electrochemical characterization in several electrolytes and finally by employing the proton trap material as the cathode in lithium and sodium batteries. These findings represent a new concept for enabling high potential organic materials for the next generation of energy storage systems.

Diversity and taxonomic identification of Shionodiscus spp. in the Australian sector of the Subantarctic Zone

Diatoms are siliceous phytoplankton that play a major role in global carbon fixation, as well as forming the basis of most marine food webs. In the Southern Ocean, diatoms are responsible for significant volumes of carbon export and sequestration in the deep sea. Diatoms are unicellular and microscopic, thus diatom taxonomy has naturally progressed as imaging and molecular technologies have developed. Despite recent advancements, some aspects of diatom taxonomy remain unclear. The genus Shionodiscus was separated from Thalassiosira in 2006, and possesses, as a group, internal extensions of the marginal strutted processes as well as a labiate process on the valve face, usually distant from the margin. The features distinguishing Shionodiscus from Thalassiosira, and Shionodiscus spp. from each other, are difficult to examine under light microscopy, and most taxonomists will group similar Shionodiscus species together when encountered, rather than discriminating species. As a result, the full extent of Shionodiscus diversity is rarely examined in individual studies. In this study, sediment trap material captured in the Australian sector of the Subantarctic Zone was examined using both light and scanning electron microscopy, and compared to known measurements on Shionodiscus species and varieties. This study had two aims; to catalogue for the first time the diversity of Shionodiscus spp. within the Australian sector, and to create a formalized set of criteria for grouping Shionodiscus species, when only light microscopy analysis is possible. By documenting Shionodiscus diversity in the Australian sector and establishing a standard identification protocol, researchers will be better able to determine the ecological significance of the genus in diatom assemblages.

Dependence of the shape of graphene nanobubbles on trapped substance

Van der Waals (vdW) interaction between two-dimensional crystals (2D) can trap substances in high pressurized (of order 1 GPa) on nanobubbles. Increasing the adhesion between the 2D crystals further enhances the pressure and can lead to a phase transition of the trapped material. We found that the shape of the nanobubble can depend critically on the properties of the trapped substance. In the absence of any residual strain in the top 2D crystal, flat nanobubbles can be formed by trapped long hydrocarbons (that is, hexadecane). For large nanobubbles with radius 130 nm, our atomic force microscopy measurements show nanobubbles filled with hydrocarbons (water) have a cylindrical symmetry (asymmetric) shape which is in good agreement with our molecular dynamics simulations. This study provides insights into the effects of the specific material and the vdW pressure on the microscopic details of graphene bubbles.

Influence of inter-annual environmental variability on chrysophyte cyst assemblages: insight from a 2-years sediment trap study in lakes from northern Poland

&lt;p&gt;Quantitative paleonvironmental studies using transfer functions are developed from training sets. However, changes in some variables (&lt;em&gt;e.g&lt;/em&gt;., climatic) can be difficult to identify from short-term monitoring (&lt;em&gt;e.g.,&lt;/em&gt; less than one year). Here, we present the study of the chrysophyte cyst assemblages from sediment traps deployed during two consecutive years (November 2011-November 2013) in 14 lakes from Northern Poland. The studied lakes are distributed along a W-E climatological gradient, with very different physical, chemical and morphological characteristics, and land-uses. Field surveys were carried out to recover the sediment trap material during autumn, along with the measurement of several environmental variables (nutrients, major water ions, conductivity, pH, dissolved oxygen and chlorophyll&lt;em&gt;-a&lt;/em&gt;). During the study, one year experienced mild seasonal changes in air temperature (November 2011-November 2012; TS1), typical of oceanic climate, while the other year was characterized by colder winter and spring (November 2012-November 2013; TS2), and higher summer temperatures, more characteristic of continental climate. Other environmental variables (&lt;em&gt;e.g&lt;/em&gt;., nutrients) did not show great changes between both years. Multivariate statistical analyses (RDA and DCA) were performed on individual TS1 and TS2 datasets. Water chemistry and nutrients (pH, TN and TP) explained the largest portion of the variance of the chrysophyte data for the individual years. However, analyses of the combined TS1 and TS2 datasets show that strong changes between summer and autumn (warm period, ice-free period with thermal stratification) and winter and spring (cold period, ice-cover period) play the most important role in the inter-annual variability in the chrysophyte assemblages. We show how inter-annual sampling maximizes ecological gradients of interest, particularly in regions with large environmental diversity, and low climatic variability. This methodology could help to identify distinct seasonal and inter-annual changes of biological communities to improve its application in paleoclimate studies.&lt;/p&gt;