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Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal–organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (>98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length: > 10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source. [ABSTRACT FROM AUTHOR]

Chemical products are ubiquitous in modern society. The chemical sector is the largest industrial energy consumer and the third largest industrial emitter of carbon dioxide. The current portfolio of mitigation options for the chemical sector emphasizes upstream "supply side" solutions, whereas downstream mitigation options, such as material efficiency, are given comparatively short shrift. Key reasons for this are the scarcity of data on the sector's material flows, and the highly intertwined nature of its complex supply chains. We provide the most up to date, comprehensive and transparent data set available publicly, on virgin production routes in the chemical sector: from fossil fuel feedstocks to chemical products. We map global mass flows for the year 2013 through a complex network of transformation processes, and by taking account of secondary reactants and by-products, we maintain a full mass balance throughout. The resulting data set partially addresses the dearth of publicly available information on the chemical sector's supply chain, and can be used to prioritise downstream mitigation options. [ABSTRACT FROM AUTHOR]

The object of this study is to design radar absorbing structures (RAS) with load-bearing ability and electromagnetic wave absorption characteristics by using conductive carbon black (CB) as absorbent and silicon carbide (SiCf)/epoxy plain-weave composites as binder matrix. The absorbing properties of single layered CB-filled SiCf/epoxy composites first increased and then decreased with increasing CB content, and when CB content was 7.5 wt %, the composite has good absorbing properties with the reflection loss value below -5 dB. In order to broaden the bandwidth, double layered absorbers were designed and simulated. It was found that when the thicknesses of the lossy layer and impedance layer were 1.0 and 2.0 mm, respectively, the reflection loss values below -10 dB can be obtained at the X band frequency range, which indicates that the SiCf/epoxy composites can be a candidate for use as radar absorbing structures. [ABSTRACT FROM AUTHOR]

A simple heat treatment, perhaps the most globally recognized point-of-use water sterilization method, is seemingly effective against all major pathogens of concern, but bulk water boiling is not energy efficient or sustainable. Herein, we present the first application of solar-to-thermal converting nanomaterials for the direct inactivation of bacteria and viruses in drinking water through the application of Au nanorods, carbon black, and Au nanorod-carbon black composite materials as light absorbers. With broad absorption bands spanning the visible and near-infrared wavelengths, at sufficient concentrations, these nanoparticles induce multiple scattering events, increasing photon absorption probability and concentrating the light within a small spatial domain, leading to localized, intense heating that inactivates microorganisms in close proximity. Moving toward practical device design, we have developed a facile silane immobilization approach to fabricate films with densely packed layers of photothermal nanomaterials. Our results suggest that upon irraditaion with simulated solar light, these films can thermally inactivate bacteria and viruses, as demonstrated through the inactivation of surrogate organisms Escherichia coli K-12, and bacteriophages MS2 and PR772. [ABSTRACT FROM AUTHOR]

A laser trapping technique is a powerful means to investigate the physical and chemical properties of single aerosol particles in a noncontact manner. However, optical trapping of strongly light-absorbing particles such as black carbon or soot is quite difficult because the repulsive force caused by heat is orders of magnitude larger than the attractive force of radiation pressure. In this study, a laser trapping and Raman microspectroscopy system using an annular laser beam was constructed to achieve noncontact levitation of single light-absorbing particles in air. Single acetylene carbon black or candle soot particles were arbitrarily selected with a glass capillary connected to a three-axis oil hydraulic micromanipulator and introduced into a minute space surrounded by a repulsive force at the focal point of an objective lens. Using the developed system, we achieved optical levitation of micrometer-sized carbonaceous particles and observation of their Raman spectra in air. Furthermore, we demonstrated in situ observations of changes in the morphology and chemical composition of optically trapped carbonaceous particles in air, which were induced by heterogeneous oxidation reactions with ozone and hydroxyl radicals. [ABSTRACT FROM AUTHOR]

High-structured carbon fillers are ubiquitous as the conductive additive comprising suspension-based electrochemical energy storage technologies. Carbon black networks provide the necessary electrical conductivity as well as mechanical percolation in the form of a yield stress. Despite their critical role in determining system performance, a full mechanistic understanding of the relationship between the electrical transport characteristics of the percolated, conductive networks of carbon black, and the rheological properties is lacking, which hinders the rational design and optimization of flowable electrodes and the processing of electrolytes for batteries. Here, we report on the microstructural origin of the rheological and electrical properties of two commonly used conductive additives in neat propylene carbonate. From quiescent mechanical and structural studies, we find that the gelation of these carbon black suspensions is best described by the dynamic arrest of a clustered fluid phase. In contrast, the temperature and frequency dependence of the ac conductivity near this transition shows that mesoscale charge transport is determined by hopping between localized states that does not require a stress-bearing network. This unique combination of microstructural characterization with rheological and electrical measurements enables testing prevailing theories of the connection between electrical and mechanical percolation as well as improving conductive additives to enhance electrochemical performance. [ABSTRACT FROM AUTHOR]

Tin (Sn) is a useful anode material for lithium ion batteries (LIBs) because of its high theoretical capacity. We fabricated oil-in-water emulsion-templated tin nanoparticle/carbon black (SnNP/CB) anodes with octane, hexadecane, 1-chlorohexadecane, and 1-bromohexadecane as the oil phases. Emulsion creaming, the oil vapor pressure, and the emulsion droplet size distribution all affect drying and thus the morphology of the dried emulsion. This morphology has a direct impact on the electrochemical performance of the anode. SnNP/CB anodes prepared with hexadecane showed very few cracks and had the highest capacities and capacity retention. The combination of low vapor pressure, creaming, which forced the emulsion droplets into a close-packed arrangement on the surface of the continuous water phase, and the small droplets allowed for gentle evaporation of the liquids during drying. This led to lower differential stresses on the sample and reduced cracking. For octane, the vapor pressure was high, the droplet sizes were large for 1-cholorohexadecane, and there was no creaming for 1-bromohexadecane. All of these factors contributed to cracking of the anode surface during drying and reduced the electrochemical performance. Choosing an oil with balanced properties is important for obtaining the best cell performance for emulsion-templated anodes for LIBs. [ABSTRACT FROM AUTHOR]

This paper presents research undertaken on pyrolytic coconut shell char to evaluate its potential as a sustainable and renewable substitute filler for carbon black in rubber. Carbon black is the most widely used filler in rubber. Its manufacture from nonrenewable feedstock is unsustainable and energy-consuming and contributes significantly to global CO2 emissions. The pyrolytic properties of coconut shell were evaluated; response surface methodology was applied to model the relationship between the pyrolysis conditions and char properties. Coconut shells were pyrolyzed using a laboratory-scale furnace under various temperatures (400-800°C), residence times (0-2 h), and atmospheric flow rates. Comparisons were made between the char and commercial carbon blacks for their physical and chemical properties (surface area and pH). Comparable char pH and surface area properties were achieved (optimal char exhibited 300 m²/g surface area). Selected samples were tested in-rubber, with the performance of the filled styrene-butadiene rubber showing 2 MPa at M100%. [ABSTRACT FROM AUTHOR]

Carbon black, a state-of-the-art cathode material for proton exchange membrane fuel cells (PEMFCs), suffers from severe corrosion in practical applications. Niobium-doped tin dioxide (NTO) is a promising alternative to support the Pt catalysts at the cathodes. Here, through a combined density functional theory and nonequilibrium Green's function study, we investigate the Nb segregation at Pt/NTO interfaces under operational electrochemical conditions, and reveal the resulting effects on the electronic transport, as well as the catalytic properties. We find that the Nb dopants tend to aggregate in the subsurface layers of the NTO substrate, whereas their transport across the Pt/NTO interface is hindered by a high thermodynamic barrier under the operating condition of PEMFCs. The interfacial transport of Sn is, however, more facile, indicating possible formations of Sn-Pt alloys and tin oxides. The electronic conductivities of the Pt/NTO systems are not particularly sensitive to the distance of the Nb dopants relative to the interface, but depend explicitly on the Nb concentration and configuration. Through a dopant induced ligand effect, the NTO substrates can improve the catalytic activity of the Pt adsorbate toward the oxygen reduction reaction. We also investigate the co-doped SnO2 substrates by both Nb and Sb elements, and find that a small amount of Nb dopants could further improve the electronic transport of the Pt/Sb-doped-SnO2 interface. The fundamental understanding generated here will help shed light on future applications of Nb-doping and Nb-Sb co-doping in Pt/SnO2 type cathodes for PEMFC applications. [ABSTRACT FROM AUTHOR]

We studied the effects of shear and its history on suspensions of carbon black (CB) in lithium ion battery electrolyte via simultaneous rheometry and electrical impedance spectroscopy. Ketjen black (KB) suspensions showed shear thinning and rheopexy and exhibited a yield stress. Shear step experiments revealed a two time scale response. The immediate effect of decreasing the shear rate is an increase in both viscosity and electronic conductivity. In a much slower secondary response, both quantities change in the opposite direction, leading to a reversal of the initial change in the conductivity. Stepwise increases in the shear rate lead to similar responses in the opposite direction. This remarkable behavior is consistent with a picture in which agglomerating KB particles can stick directly on contact, forming open structures, and then slowly interpenetrate and densify. The fact that spherical CB particles show the opposite slow response suggests that the fractal structure of the KB primary units plays an important role. A theoretical scheme was used to analyze the shear and time-dependent viscosity and conductivity. Describing the agglomerates as effective hard spheres with a fractal architecture and using an effective medium approximation for the conductivity, we found the changes in the derived suspension structure to be in agreement with our qualitative mechanistic picture. This behavior of KB in flow has consequences for the properties of the gel network that is formed immediately after the cessation of shear: both the yield stress and the electronic conductivity increase with the previously applied shear rate. Our findings thus have clear implications for the operation and filling strategies of semisolid flow batteries. [ABSTRACT FROM AUTHOR]

This work reports on the importance of adsorption and passivation phenomena during the electro-oxidation of phenolic mixture. A case study of the anodic oxidation of phenol and 2-chlorophenol was performed. A carbon black-diamond electrode with 20% carbon black (20CBD electrode) was used as the anode. The anodic oxidation behaviors of 100 mg/L phenol and 100 mg/L 2-chlorophenol on the 20CBD electrode were investigated using cyclic voltammetry in aqueous solutions of 0.25 M Na2SO4. The electrochemical impedance technique was used to investigate the effects of electrode passivation and the adsorption of phenol and 2-chlorophenol through the electrochemical degradation process. The results showed that oxidation of 2-chlorophenol was easier than that of phenol. Even in a 1:1 mixture of 2-chlorophenol and phenol, each at 100 mg/L, the removal rate of 2-chlorophenol was higher than that of phenol. After 6 h, up to 94% of the 2-chlorophenol had degraded, whereas only 20% of the phenol had degraded in the same time. The mass-transfer resistance of phenol was up to 10 times higher than that of 2-chlorophenol. Moreover, the passivation resistance generated on the electrode surface by phenol oxidation was also higher than that generated by 2-chlorophenol oxidation. [ABSTRACT FROM AUTHOR]

Carbon allotropes nanomaterials are explored here for the preparation of highly efficient tubular micromotors: 0D (C60 fullerene), 1D (carbon nanotubes), 2D (graphene), and 3D (carbon black, CB). The micromotors are prepared by direct electrochemical reduction or deposition of the nanomaterial into the pores of a membrane template. Subsequent electrodeposition of diverse inner catalytic layers (Pt, Pd, Ag, Au, or MnO2) allows for efficient bubble-propulsion in different media (seawater, human serum, and juice samples). Atomic-force microscopy (AFM) and scanning electron microscopy characterization reveals that the micromotors exhibit a highly rough outer surface and highly microporous inner catalytic structures. A key aspect derived from the AFM characterization is the demonstration that the rough outer surface of the micromotors can greatly affect their overall speed. To date, the literature has only focused on studying the effect of the inner catalytic layer upon their speed and performance and has underestimated the effect of the outer surface layer. The speed of carbon-based micromotors is a compromise between two opposite forces: the increased catalytic activity because of improved fuel decomposition in the inner catalytic layer, which propels their advance, and the friction of the rough outer surface with the fluid, which is opposed to it. The largest outer surface area associated with the highest surface roughness of C60 fullerene and carbon black-Pt micromotors leads to a large friction force, which results in a reduced speed of -180 μm/s (1% H2O2). In contrast, for carbon-nanotube-Pt based micromotors, the dominant force is the high catalytic activity of the micromotor, which allows them to reach ultrafast speeds up to 440 μm/s (1% H2O2). The new protocol opens new avenues for the universal preparation of carbon based multifunctional micromotors for a myriad of practical applications exploiting the features of carbon allotropes. [ABSTRACT FROM AUTHOR]

Graphitized carbon black (GCB) has been employed for extraction of several classes of analytes, due to the large surface area and the unique chemistry of its surface groups that allows for extracting a wide range of analytes, including polar, acidic compounds. Despite the fact that structurally related materials, such as graphene, found application as hybrid-components in phosphoproteomics, surprisingly, GCB has never been used for the selective enrichment of phosphopeptides. For this purpose, in the present work we used GCB to prepare a magnetic composite with TiO2 (mGCB@TiO2) that was then applied to yeast total extracts. We exploited the high surface area provided by nanostructures, the presence of nano-TiO2 for selective binding of phosphopeptides, and the magnetic responsiveness of magnetite for solid-phase separation. The material was extensively characterized at each modification step by transmission electron microscopy, Fourier-transformed infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, and porosimetry. Next, the new system was applied for the enrichment of casein phosphopeptides from a simulated tryptic digest with bovine serum albumin (BSA:casein, 100:1). Finally, after assessing the potential applicability, the composite was employed for enriching phosphopeptides from yeast protein digests. This allowed us not only to optimize the enrichment protocol but also to fully compare its performance to commercial TiO2 spin columns. To achieve this aim, the optimized enrichment protocol was included in a typical shotgun proteomics analytical workflow based on nanoHPLC- MS/MS analysis. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is the major reaction that occurs at the cathodes of fuel cells and metal-air batteries. Development of inexpensive, active, and durable heteroatom doped carbon-based ORR catalysts can lead to significant cost reduction of these electrochemical energy devices, which therefore has recently attracted enormous research attentions. This work reports a three-dimensional porous composite (P-g-C3N4@NH2-CB) for the highly efficient ORR catalyst. P-g-C3N4@NH2-CB was prepared by mixing phosphorus-doped graphitic carbon nitride nanosheets (P-g-C3N4 NSs) with NH2-functionalized carbon black (NH2-CB) via a novel self-assembly approach. The NH2-CB was rationally chosen as the spacer that enables the self-assembled with the P-g-C3N4 NSs driven by the electrostatic interaction. The intercalation of NH2-CB induces the transformation of 2-D P-g-C3N4 NSs into a 3-D composites material of higher surface area, thereby exposing more ORR active sites. The P-g-C3N4@NH2-CB exhibited a remarkable ORR activity with an electron transfer number of 3.83 and Tafel slope of 89 mV dec-1 in alkaline electrolyte, which is comparable to the ORR performance on Pt/Vulcan XC-72. It is found that the incorporated P atoms as well as employing NH2-CB spacer not only reduces the overpotential of ORR, but also enhances the ORR activity of carbon nitride-based materials, owing to the synergistic effect between P and N in tri-s-triazine rings of carbon nitrides and the optimum interaction between the oppositely charged P-g-C3N4 and NH2-CB. [ABSTRACT FROM AUTHOR]

The first order approximation (FOA3) currently employed to estimate BC mass emissions underpredicts BC emissions due to inaccuracies in measuring low smoke numbers (SNs) produced by modern high bypass ratio engines. The recently developed Formation and Oxidation (FOX) method removes the need for and hence uncertainty associated with (SNs), instead relying upon engine conditions in order to predict BC mass. Using the true engine operating conditions from proprietary engine cycle data an improved FOX (ImFOX) predictive relation is developed. Still, the current methods are not optimized to estimate cruise emissions nor account for the use of alternative jet fuels with reduced aromatic content. Here improved correlations are developed to predict engine conditions and BC mass emissions at ground and cruise altitude. This new ImFOX is paired with a newly developed hydrogen relation to predict emissions from alternative fuels and fuel blends. The ImFOX is designed for rich-quench-lean style combustor technologies employed predominately in the current aviation fleet. [ABSTRACT FROM AUTHOR]

A facile approach for improving the dispersion of carbon black (CB) with a few functional groups in a rubber matrix was developed by preparing a new solution-polymerized styrene-butadiene-p-(2,2′-diphenylethyl)styrene (DPES) rubber (SBDR). The SBDR was shown to graft onto the surface of the CB through trapping a polymer radical formed by thermally dissociation of a triphenylethane pendant. The dispersion of CB in the rubber matrix was markedly improved by increasing the DPES content in SBDR, as demonstrated by transmission electron microscopy, small-angle X-ray scattering, and rubber process analysis. Furthermore, SBDR vulcanizates showed improved mechanical properties and good dynamic properties for tread rubber with increasing DPES content. This research provides a universal method for improving the dispersion of carbon materials containing few functional groups in polymer matrices. [ABSTRACT FROM AUTHOR]

Methods for chemical surface functionalization for carbon black (CB) nanoparticles were studied to produce (CB)/polypropylene (PP) nanocomposites with superior electrical and thermal properties. Nanoparticle dispersion is known to directly control the extent to which nanocomposites maximize the unique attributes of their nanoscale fillers. As a result, tailored nanoparticle surface chemistry is a widely utilized method to enhance the interfacial interactions between nanoparticles and polymer matrices, assisting improved filler dispersion. In this work, a rapid chemical functionalization approach using a number of diarylcarbene derivatives, followed by the azo-coupling of substituted diazonium salts, for the covalent introduction of selected functional groups to the CB surface, is reported. Characterization of the modified CB by XPS, TGA, CHN, and ATR-IR collectively confirmed surface functionalization, estimating surface grafting densities of the order of 1013 and 1014 molecules/cm². Nanocomposites, synthesized by solvent mixing PP with pristine and modified CB, demonstrated macroscopic property changes as a result of the nanoparticle surface functionalization. Pronounced improvements were observed for PP nanocomposites prepared with a dodecyl-terminated diaryl functionalized CB, in which TEM analysis established improved nanofiller dispersion owing to the enhanced CB-PP interfacial interactions in the nanocomposite. Observed dielectric relaxation responses at 20 wt % loading and a reduced percolation threshold realized conductivities of 1.19 × 10-4 S cm-1 at 10 wt %, compared to 2.62 × 10-15 S cm-1 for pristine CB/PP nanocomposites at the same filler loading. In addition, thermal properties signify an increase in the number of nucleation sites by the raised degree of crystallinity as well as increased melting and crystallization temperatures. [ABSTRACT FROM AUTHOR]

Transition-metal (TM) nanoparticles supported on oxides or carbon black have attracted much attention as potential catalysts for ethanol steam reforming reactions for hydrogen production. To improve the performance of nanocatalysts, a fundamental understanding of the interaction mechanism between water and ethanol with finite TM particles is required. In this article, we employed first-principles density functional theory with van der Waals (vdW) corrections to investigate the interaction of ethanol and water with TM13 clusters, where TM = Ni, Cu, Pd, Ag, Pt, and Au. We found that both water and ethanol bind via the anionic O atom to onefold TM sites, while at higher-energy structures, ethanol binds also via the H atom from the CH2 group to the TM sites, which can play an important role at real catalysts. The putative global minimum TM13 configurations are only slightly affected upon the adsorption of water or ethanol; however, for few systems, the compact higher-energy icosahedron structure changes its configuration upon ethanol or water adsorption. That is, those configurations are only shallow local minimums in the phase space. Except few deviations, we found similar trends for the magnitude of the adsorption energies of water and ethanol, that is, Ni13 > Pt13 > Pd13 and Cu13 > Au13 > Ag13, which is enhanced by the addition of the vdW correction (i.e., from 4% to 62%); however, the trend is the same. We found that the magnitude of the adsorption energy increases by shifting the center of gravity of the d-states toward the highest occupied molecular orbital. On the basis of the Mulliken and Hirshfeld charge analysis, as well as electron density differences, we identified the location of the charge redistribution and a tiny charge transfer (from 0.01 e to 0.19 e) from the molecules to the TM13 clusters. Our vibrational analysis indicates the red shifts in the OH modes upon binding of both water and ethanol molecules to the TM13 clusters, suggesting a weakening of the O-H bonding. [ABSTRACT FROM AUTHOR]

Although adverse health effects of carbon black (CB) exposure are generally accepted, a direct, label-free approach for detecting CB particles in fluids and at the cellular level is still lacking. Here, we report nonincandescence related white-light (WL) generation by dry and suspended carbon black particles under illumination with femtosecond (fs) pulsed near-infrared light as a powerful tool for the detection of these carbonaceous materials. This observation is done for four different CB species with diameters ranging from 13 to 500 nm, suggesting this WL emission under fs near-infrared illumination is a general property of CB particles. As the emitted radiation spreads over the whole visible spectrum, detection is straightforward and flexible. The unique property of the described WL emission allows optical detection and unequivocal localization of CB particles in fluids and in cellular environments while simultaneously colocalizing different cellular components using various specific fluorophores as shown here using human lung fibroblasts. The experiments are performed on a typical multiphoton laser-scanning microscopy platform, widely available in research laboratories. [ABSTRACT FROM AUTHOR]

The nature of filler-polymer and filler-filler interactions in rubber composites under strain remains an open question in soft matter physics. These interactions are key to explaining the rich variety of complex behavior exhibited by particle-filled rubber products. In this paper we demonstrate a simultaneous dielectric/dynamic mechanical analysis technique (SDMS) which provides new insights into the structure-property relationships of filled rubbers. The complex permittivity of carbon black filled natural rubber has been characterized under a simultaneous tensile strain field (from 0.1% to 50%). The complex permittivity exhibits a dramatic nonlinear dependence on strain coupled with features which are analogous to mechanical strain softening and strain history, namely the "Payne" and "Mullins" effects. The sensitivity of the complex permittivity to such effects is several orders of magnitude greater than in corresponding, traditional mechanical tests. In addition, we demonstrate for the first time that it is possible to use both strain and electrical field frequency as "dipole filters" which can be used to selectively probe the dipoles present at the polymer-filler interface. [ABSTRACT FROM AUTHOR]

A novel one-step compression molding was proposed and successfully employed for preparation of closed-cell foams based on natural rubber (NR)/carbon black (CB) composite. The uniqueness of this new method was that both the foam density and expansion ratio became independent of the CB content. The rheometrical findings indicated that the increase in the CB content from 0 to 20 phr yielded a 0.91 and 3.51 N m increase in the initial and the final torque, respectively. The SEM results demonstrated that the prepared foam had three different layers including the skin, transition, and core layers. Almost 14-fold enhancement of the cell density (from 8 to 117 cells/cm³) was obtained by increasing the CB content in a constant foam density. Although, curing properties, cell morphology, and mechanical properties of the foam improved by increasing the CB content, the gradual deterioration was observed for sound absorption properties. [ABSTRACT FROM AUTHOR]

Carbon black filled natural rubber (CB/NR) is a paradigm of nanocomposite materials with high performances. However, the mechanism for the nonlinear Payne effect is still not fully clear. CB gel (CBG) network embedded in the entanglement rubber matrix is supposed to be crucial for the reinforcement and viscoelastic nonlinearity. In this paper, we report for the first time the preparation of bulk CBGs by extracting the highly filled compounds in toluene and the systematic study of their viscoelastic behaviors. The CBG obtained from highly filled compounds with CB loadings from 40 to 70 phr has almost identical microstructure and composition, containing 40 wt % inextractable rubber fractions, among which ∼12 wt % is glassy. Dynamic rheological studies show that the Payne effect of the CBG network is frequency-independent and highly resilient, exhibiting an unjamming characteristic. On the other hand, the Payne effect of highly filled compounds is determined by the coupling between the breakdown of CBG network and the frequency-dependent chain disentanglement of extractable rubber fractions. This work provides new insights into the Payne effect of CB filled NR and should merit designing other rubbery nanocomposites with high performances and functions. [ABSTRACT FROM AUTHOR]

Carbon black filled natural rubber (CB/NR) is a paradigm of nanocomposite materials with high performances. However, the mechanism for the nonlinear Payne effect is still not fully clear. CB gel (CBG) network embedded in the entanglement rubber matrix is supposed to be crucial for the reinforcement and viscoelastic nonlinearity. In this paper, we report for the first time the preparation of bulk CBGs by extracting the highly filled compounds in toluene and the systematic study of their viscoelastic behaviors. The CBG obtained from highly filled compounds with CB loadings from 40 to 70 phr has almost identical microstructure and composition, containing 40 wt % inextractable rubber fractions, among which ~12 wt % is glassy. Dynamic rheological studies show that the Payne effect of the CBG network is frequency-independent and highly resilient, exhibiting an unjamming characteristic. On the other hand, the Payne effect of highly filled compounds is determined by the coupling between the breakdown of CBG network and the frequency-dependent chain disentanglement of extractable rubber fractions. This work provides new insights into the Payne effect of CB filled NR and should merit designing other rubbery nanocomposites with high performances and functions. [ABSTRACT FROM AUTHOR]

Oil foams are composed of gas bubbles dispersed in an oil phase. These systems are scarcely studied despite their great potential in diverse fields such as the food and cosmetic industries. Contrary to aqueous foams, the production of oil foams is difficult to achieve due to the inefficiency of surfactant adsorption at oil-air interfaces. Herein, we report a simple way to produce oil foams from oleogels, whose liquid phase is a mixture of sunflower oil and fatty alcohols. The temperature at which the oleogel formed was found to depend on both fatty alcohol chain length and concentration. The air bubbles in the oleogel foam were stabilized by fatty alcohol crystals. Below the melting temperature of the crystals, oleogel foams were stable for months. Upon heating, these ultrastable foams collapsed within a few minutes due to the melting of the crystal particles. The transition between crystal formation and melting was reversible, leading to thermoresponsive nonaqueous foams. The reversible switching between ultrastable and unstable foam depended solely on the temperature of the system. We demonstrate that these oleogel foams can be made to be photoresponsive by using internal heat sources such as carbon black particles, which can absorb UV light and dissipate the absorbed energy as heat. This simple approach for the formulation of responsive oil foams could be easily extended to other oleogel systems and could find a broad range of applications due to the availability of the components in large quantities and at low cost. [ABSTRACT FROM AUTHOR]

Sootformation in diesel engines is known to cause premature engine wear.Unfortunately, genuine diesel soot is expensive to generate, so carbonblacks are often used as diesel soot mimics. Herein, the suitabilityof a commercial carbon black (Regal 250R) as a surrogate for dieselsoot dispersed in engine base oil is examined in the presence of twocommonly used polymeric lubricant additives. The particle size, morphology,and surface composition of both substrates are assessed using BETsurface area analysis, TEM, and XPS. The extent of adsorption of apoly(ethylene-co-propylene) (dOCP) statistical copolymeror a polystyrene-block-poly(ethylene-co-propylene) (PS–PEP) diblock copolymer onto carbon black ordiesel soot from n-dodecane is compared indirectlyusing a supernatant depletion assay technique via UV spectroscopy.Thermogravimetric analysis is also used to directly determine theextent of copolymer adsorption. Degrees of dispersion are examinedusing optical microscopy, TEM, and analytical centrifugation. SAXSstudies reveal some structural differences between carbon black anddiesel soot particles. The mean radius of gyration determined forthe latter is significantly smaller than that calculated for the former, and in the absence of any copolymer, diesel soot suspended in n-dodecane forms relatively loose mass fractals comparedto carbon black. SAXS provides evidence for copolymer adsorption andindicates that addition of either copolymer transforms the initiallycompact agglomerates into relatively loose aggregates. Addition ofdOCP or PS–PEP does not significantly affect the structureof the carbon black primary particles, with similar results beingobserved for diesel soot. In favorable cases, remarkably similar datacan be obtained for carbon black and diesel soot when using dOCP andPS–PEP as copolymer dispersants. However, it is not difficultto identify simple copolymer–particle–solvent combinationsfor which substantial differences can be observed. Such observationsare most likely the result of dissimilar surface chemistries, whichcan profoundly affect the colloidal stability. [ABSTRACT FROM AUTHOR]

An automatable flow system for the continuous and long-term monitoring of the phosphate level has been developed using an amperometric detection method based on the use of a miniaturized sensor. This method is based on the monitoring of an electroactive complex obtained by the reaction between phosphate and molybdate that is consequently reduced at the electrode surface. The use of a screen-printed electrode modified with carbon black nanoparticles (CBNPs) leads to the quantification of the complex at low potential, because CBNPs are capable of electrocatalitically enhancing the phosphomolybdate complex reduction at +125 mV versus Ag/AgCl without fouling problems. The developed system also incorporates reagents and waste storage and is connected to a portable potentiostat for rapid detection and quantification of phosphate. Main analytical parameters, such as working potential, reagent concentration, type of cell, and flow rate, were evaluated and optimized. This system was characterized by a low detection limit (6 μM). Interference studies were carried out. Good recovery percentages comprised between 89 and 131.5% were achieved in different water sources, highlighting its suitability for field measurements. [ABSTRACT FROM AUTHOR]

The solution behavior of a polystyrene–hydrogenated polyisoprene star diblock copolymer(Mn∼ 384 K; 6 mol % polystyrene)is examined in nonpolar media. Variable temperature 1HNMR studies using deuterated n-dodecane confirm thatthe outer polystyrene blocks are only partially solvated in n-dodecane at 25 °C: the apparent polystyrene contentof 3.2 ± 0.2 mol % remains essentially constant on heating upto 100 °C. Physical adsorption of this star diblock copolymeronto carbon black particles is examined, with particular attentionbeing paid to the effect of copolymer concentration on colloidal stability.An isotherm is constructed for copolymer adsorption onto carbon blackfrom n-dodecane at 20 °C using a supernatantdepletion assay based on UV spectroscopy analysis of the aromaticchromophore in the polystyrene block. Langmuir-type adsorption isobserved with a maximum adsorbed amount, Γ, of ∼2.2 ±0.1 mg m–2. In addition, thermogravimetric analysisis used to directly determine the amount of adsorbed copolymer onthe carbon black particles, which are essentially incombustible underan inert atmosphere. Analytical centrifugation, optical microscopy,and transmission electron microscopy studies indicate that the stardiblock copolymer acts as an effective flocculant at low concentration,with steric stabilization only being observed above a certain criticalcopolymer concentration (∼5.5% w/w based on carbon black). This is attributed tothe spatial location of the polystyrene block and the star copolymerarchitecture, which enables copolymer adsorption onto multiple carbonblack particles at low coverage, leading to bridging flocculation.Above 5.5% w/w copolymer, the surface coverage is sufficiently highthat all of the polystyrene “stickers” adsorb onto singlecarbon black particles, resulting in colloidally stable, stericallystabilized carbon black dispersions. Small-angle X-ray scattering(SAXS) is also used to characterize the copolymer-coated carbon blackparticles: this technique provides useful complementary insights regardingthe rather subtle changes in the fractal morphology that occur withincreasing copolymer concentration. Moreover, SAXS also provides directevidence for the presence of the copolymer chains at the particlesurface. [ABSTRACT FROM AUTHOR]

Adsorption of different gases ongraphitized thermal carbon black(GTCB) has been studied with a new molecular model to examine theconsequences of micropore crevices and functional groups at the junctionsbetween adjacent basal planes. Adsorption was simulated in the GrandCanonical Monte Carlo ensemble and the theoretical Henry constantswere calculated by Monte Carlo volume integration over the Boltzmannfactor of the solid–fluid potential. The simulation resultsare in good agreement with high-resolution experimental isothermsfor argon on mineralogical graphite measured by Lopez-Gonzalez etal.1 From detailed inspection of the argonisotherms at extremely low coverages, we find two distinct Henry lawregions, separated by a plateau (suggesting saturation of the strongersites) that spans over a few decades of pressure. The first Henrylaw region is attributed to adsorption in the ultrafine crevices atthe junctions between two adjacent basal planes, and the second regioncorresponds to adsorption on the basal plane, as confirmed by thetheoretical Henry constant. The simulated isosteric heat and snapshotsof molecular configurations show that argon adsorbs preferentiallyin the ultrafine crevices where there is a deep potential well dueto overlap from the opposite pore walls. Similar behavior was foundfor other nonassociating fluids (Ar, N2, and CO2); however, for associating fluids (NH3and H2O), the strong sites for adsorption and nucleation come from thecombined effects of functional groups and ultrafine crevices, sincethe latter cannot alone account for the observed adsorption. [ABSTRACT FROM AUTHOR]

Weuse para-amino benzoic acid terminated carbonblack (CB) as a model particulate material to study the effect ofsalt-modulated attractive interactions on phase behavior and steadyshear stresses in suspensions and particle-stabilized emulsions. Surprisingly,the suspension displayed a yield stress at a CB volume fraction ofϕCB= 0.008. The yield stress scaled with CB concentrationwith power law behavior; the power law exponent changed abruptly ata critical CB concentration, suggesting a substantial change in networkstructure. Cryogenic scanning electron microscopy revealed structuraldifferences between the networks found in each scaling regime. Randomlyoriented pores with thick CB boundaries were observed in the scalingregion above the critical particle concentration, suggesting a stronggel network, and long, oriented pores were found in the scaling regionbelow the critical particle concentration, suggesting a weak networkinfluenced by an induced shear stress. These findings correlate withthe existence of gels and transient networks. Transient networks breakdown under gravitational forces over time periods of 12−24hours. The yield stresses of CB-gels containing oil emulsion dropletswere found to scale with carbon black concentration similar to theCB-gels without oil. These results offer insight into salt-inducedattractive colloidal networks and the difference in structure andyield-stress behavior between transient networks and gels. Furthermore,CB offers the ability to stabilize an oil phase in discrete dropletsand contain them within a rigid network structure. [ABSTRACT FROM AUTHOR]

The application ofan electric field to a suspension of chargedparticles can lead to the formation of patterns due to electrohydrodynamicinstabilities which remain poorly understood. We elucidate this behaviorby visualizing the dynamics of charged carbon black particles suspendedin a nonpolar solvent in response to an electric field. As the particlesare transported across a microfluidic channel, an instability occursin which the initially uniform, rapidly advancing particle front developsfingers. Furthermore, when the direction of the applied field is repeatedlyswitched, the particles localize into a remarkably well-defined periodicpattern which reflects an interplay between the fingering instabilityand particle diffusion. [ABSTRACT FROM AUTHOR]

Carboxyl-terminatedcarbon black (CB) particles have been proposed as readily available,biocompatible dispersants to stabilize oil-in-water emulsions afteran oil spill. Since the reduction in interfacial tension and the increasein interfacial elasticity are the key parameters which relate interfacialmechanics to emulsion stability, this investigation explores the effectof CB adsorption and surface coverage on oil–water interfacialtension and elasticity. Flocculation of CB was explored as ionic strengthwas increased from 0 to 0.6 M, approximately the salinity of seawater.As salinity increases, CB aggregates into larger particles from 100nm to 6 μm. The interfacial tension and dilational viscoelasticitywere measured for two systems: a drop of a CB suspension in oil andan inverted oil drop in a CB suspension. For the arrangement of aCB suspension drop in oil, most of the CB settles and accumulatestoward the bottom of the drop with only small surface adsorption andno appreciable effect is observed on the dynamic interfacial tensionor the dilational viscoelasticity. On reversing the arrangement toan inverted oil drop in CB suspension and increasing the convectionof the outer phase, the surface coverage increases considerably. TheCB coverage becomes more uniform with higher convection with an averagevalue of approximately 2.6 g/m2, which is representativeof the coverage in Pickering emulsions stabilized by CB particles.The CB coverage decreases the surface tension from about 30 to 8.5mN/m accompanied by an increase in the surface elasticity to 20.7mN/m. The sharp contrast between the results from the CB suspensiondrop and the oil drop could be partially due to the effect of thewetting characteristics of the particles or due to the significantdifferences between the convection in the two cases. [ABSTRACT FROM AUTHOR]

Diffusion of deuterated polystyrene(dPS) is probed in PS matricescontaining stringlike chained nanoparticles (cNP) grafted with PS.This investigation connects prior diffusion studies in model sphericaland cylindrical NP systems and provides insight for technologicalapplications, which typically involve irregularly shaped NPs suchas carbon black. We report that the presence of chained NPs in PSmatrices induces a minimum in the diffusion coefficient (D) with increasing cNP concentration when the key length scale, 2Rg/L≤ 1.5, where Rgis the gyration radius of dPS and Lis the mean length of the impenetrable core of the chainedNPs. When 2Rg/L>1.5, Ddecreases monotonically as the NP concentrationincreases.Note that in all cases 2Rgis larger thanthe diameter of these short-stringy NPs. The diffusion minimum isattributed to anisotropic diffusion in the vicinity of the chainedNPs and requires that the long dimension of the cNP be comparableto or longer than the tracer molecule. Two normalizations are exploredto provide insight about the diffusion mechanism: D/D0where D0is the diffusion coefficient in a pure homopolymer matrix and D/Dewhere Deis an effective diffusion coefficient that accountsfor the distinct dynamics in the PS matrix and PS brush regions. For D/D0, a sharp transition froma diffusion minimum to a monotonic decrease is observed as dPS molecularweight increases, while for D/Dethe transition is more gradual. These studies show not onlythat the NPs act as impenetrable obstacles for polymer diffusion butthat the polymer brush grafted to the cNP provides an alternativepathway to control polymer dynamics. [ABSTRACT FROM AUTHOR]

Noniridescentstructural color pigments have great potential asalternatives to conventional chemical color pigments in many colorationapplications due to their nonbleaching and color-tunable properties.In this work, we report a novel method to create photonic microgranulescomposed of glassy packing of silica particles and small fractionof carbon black nanoparticles, which show pronounced structural colorswith low angle-dependency. To prepare isotropic random packing ineach microgranule, a Leidenfrost drop, which is a drop levitated byits own vapor on a hot surface, is employed as a template for fastconsolidation of silica particles. The drop randomly migrates overthe hot surface and rapidly shrinks, while maintaining its sphericalshape, thereby consolidating silica particles to granular structures.Carbon black nanoparticles incorporated in the microgranules suppressincoherent multiple scattering, thereby providing improved color contrast.Therefore, photonic microgranules in a full visible range can be preparedby adjusting the size of silica particles with insignificant whitening. [ABSTRACT FROM AUTHOR]

Carbonblack (CB) was encapsulated with branched poly(styrene-alt-maleic anhydride) (BPSMA) by phase separation methodfor use in textile printing. Experimental results showed that, whenBPSMA was synthesized using a molar ratio of the chain transfer agent(4-vinylphenyl methanethiol) to monomers (styrene and maleic anhydride)at 6:94 and a mass ratio of the initiator (benzoyl peroxide) to monomersat 1:50, the encapsulated CB was constructed with a smallest particlesize and as such a highest stability to temperature. An optimizedBPSMA-encapsulated CB dispersion was achieved by adding BPSMA andCB at mass ratio of 1:5 and maintaining pH at 10. The BPSMA-encapsulatedCB composite was characterized using Scanning electron microscope,Fourier-transform infrared spectroscopy, thermo gravimetric analyzer,and drop shape analyzer. The BPSMA-encapsulated CB dispersion wasdemonstrated to have an excellent performance for printing cottonfabric. [ABSTRACT FROM AUTHOR]

Black carbon (BC) mass and solid particle number emissions were obtained from two pairs of gasoline direct injection (GDI) vehicles and port fuel injection (PF1) vehicles over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) drive cycles on gasoline and 10% by volume blended ethanol (E10). BC solid particles were emitted mostly during cold-start from all GDI and PFI vehicles. The reduction in ambient temperature had significant impacts on BC mass and solid particle number emissions, but larger impacts were observed on the PFI vehicles than the GDI vehicles. Over the FTP-75 phase I (cold-start) drive cycle, the BC mass emissions from the two GDI vehicles at 0 °F (-18 °C) varied from 57 to 143 mg/mi, which was higher than the emissions at 72 °F (22 °C; 12-29 mg/mi) by a factor of 5. For the two PFI vehicles, the BC mass emissions over the FTP-75 phase 1 drive cycle at 0 °F varied from 111 to 162 mg/mi, higher by a factor of 44-72 when compared to the BC emissions of 2-4 mg/mi at 72 °F. The use of a gasoline particulate filter (GPF) reduced BC emissions from the selected GDI vehicle by 73-88% at various ambient temperatures over the FTP-75 phase 1 drive cycle. The ambient temperature had less of an impact on particle emissions for a warmed-up engine. Over the US06 drive cycle, the GPF reduced BC mass emissions from the GDI vehicle by 59-80% at various temperatures. E10 had limited impact on BC emissions from the selected GDI and PFI vehicles during hot-starts. E10 was found to reduce BC emissions from the GDI vehicle by 15% at standard temperature and by 75% at 19 °F (-7 °C). [ABSTRACT FROM AUTHOR]

Iron complexes of tetra-amido macrocyclic ligands are important members of the suite of oxidation catalysts known as TAML activators. TAML activators are known to be fast homogeneous water oxidation (WO) catalysts, producing oxygen in the presence of chemical oxidants, e.g., ceric ammonium nitrate. These homogeneous systems exhibited low turnover numbers (TONs). Here we demonstrate immobilization on glassy carbon and carbon paper in an ink composed of the prototype TAML activator, carbon black, and Nafion and the subsequent use of this composition in heterogeneous electrocatalytic WO. The immobilized TAML system is shown to readily produce O2 with much higher TONs than the homogeneous predecessors. [ABSTRACT FROM AUTHOR]

A seriesof oxygen depolarized cathodes (ODC) with different gasdiffusion layers (GDLs), determined by different carbon black fillers,PTFE contents, and pore-forming agents, were fabricated. The structure-sensitiveactivity for the oxygen reduction reaction (ORR) on these cathodeshas been studied in alkaline solutions, with the aim of revealingthe effect of pore structures in GDLs on the ORR activity. A linear-typegas permeability (K) dependence on the ORR activityis observed, indicating that Kis one of the keyparameters representative of the ability of gas diffusion throughGDLs. The added PTFE as binder favors the formation of the secondarypores instead of the primary pores in GDLs. By introducing (NH4)2C2O4as pore-forming agentsin GDL, the best performance of the ODC was obtained. The resultingGDL possessed the average secondary pore diameter of 144 nm and thesecondary pore volume of 0.3032 mL/g. [ABSTRACT FROM AUTHOR]

The catalytic carbonization of polyolefin materials to synthesize carbon nanotubes (CNTs) is a promising strategy for the processing and recycling of plastic wastes, but this approach is generally limited due to the selectivity of catalysts and the difficulties in separating the poh/olefin mixture. In this study, the influence of nanosized carbon black (CB) and Ni2O3 as a novel combined catalyst system on catalyzing carbonization of polypropylene (PP), polyethylene (PE), polystyrene (PS) and their blends was investigated. We showed that this combination was efficient to promote the carbonization of these polymers to produce CNTs with high yields and of good quality. Catalytic pyroiysis and model carbonization experiments indicated that the carbonization mechanism was attributed to the synergistic effect of the combined catalysts rendered by CB and Ni2O3: CB catalyzed the degradation of PP, PE, and PS to selectively produce more aromatic compounds, which were subsequently dehydrogenated and reassembled into CNTs via the catalytic action of CB together with Ni particles. Moreover, the performance of the synthesized CNTs as the electrode of supercapacitor was investigated. The supercapacitor displayed a high specific capacitance as compared to supercapacitors using commercial CNTs and CB. This difference was attributed to the relatively larger specific surface areas of our synthetic CNTs and their more oxygen-containing groups. [ABSTRACT FROM AUTHOR]

Black carbon soot (BS) is consideredto be the second most contributingorganic matter next to carbon dioxide for the global warming effect.There is, however, so far no consensus on the quantitative warmingeffect due to the increased distribution of black carbon in the atmosphere.A recent report (Science2012, 337, 1078) suggests that due to BS there is only a few percentage enhancementin absorption of BS-immersed aerosols. To get proper interpretationof the available experimental data, it becomes essential to obtaindetails of the microscopic origin of the absorption and scatteringprocesses of the aerosol clusters due to the presence of soot. However,so far, due to the large spatial scale and the need for a quantummechanical description of the particles involved in the absorptionand scattering, this quest has posed an insurmountable challenge.In the present work we propose the use of a multiscale integratedapproach based on molecular dynamics and a quantum mechanical–molecularmechanical method to model the optical property of molecules immersedin nanosized aerosol particles. We choose fluoranthene (FA) with varying cis-pinonic acid (CPA) impurity concentration as an illustrativeexample of application. We observe that normally FA tends to be onthe surface of the nanoaerosols but in the presence of CPA impuritiesits spatial location changes to a core aggregate to some extent. Wefind that the absorption maximum is only slightly red-shifted in thepresence of increased CPA concentrations and that the oscillator strengthsare not altered significantly. The comparable values for the oscillatorstrengths of all the low energy excitations suggest that the absorptionenhancement of the aerosol due to BS will not be substantial, whichis in line with the recent experimental report in Science. [ABSTRACT FROM AUTHOR]

The article discusses production of acetylene and acetylene-based chemicals from coal. Topics discussed include acetylene synthesis via calcium carbide route and its use as fuel for oxyacetylene welding and cutting torches, synthesis of carbon black via incomplete combustion of hydrocarbons, synthesis of trichloroethylene and its use as a degreaser for metal surfaces. Also discussed are hydrogenation of acetylene to ethylene and reaction of acetylene with alkylphenols to produce resins.

Tosimultaneously improve electrical conductivity and toughnessof polyamide 6 (PA 6), carbon black (CB) nanoparticles and maleicanhydride grafted polyethylene–octene copolymer (POE-g-MA)were compounded with PA 6 by melt compounding, and the influencesof CB and POE-g-MA components on the electrical conductivity and mechanicalproperties of PA 6 nanocomposites were investigated. The additionof CB improves the electrical conductivity and Young’s modulusof PA 6. With 40 wt % POE-g-MA and 15 wt % CB, the nanocomposite exhibitsa high notched impact energy of 73.9 kJ/m2and an electricalconductivity of 7.1 × 10–6S/m. Interestingly,the presence of POE-g-MA reduces the electrical percolation thresholdof the PA 6 nanocomposites due to the selective localization of CBin the PA 6 matrix. Compared to PA 6/CB binary nanocomposites, theternary nanocomposites exhibit both higher electrical conductivityand supertoughness. [ABSTRACT FROM AUTHOR]

Nanoparticles(silica, carbon black, etc.) are often used as fillers to improvephysical (thermal conducticity, coefficient of thermal expansion)and mechanical (modulus, strength) properties of polymer materials.In many cases, however, lack of nanoparticle dispersion in the polymerlimits the utility of a resulting nanocomposite material. To improvedispersion, one often grafts organic chains (“ligands”)onto the surface of the particles; if the ligands are chemically misciblewith the matrix polymer, it helps the particles to disperse more uniformly.The relationship between ligand length and grafting density, on theone hand, and the nanocomposite morphology, on the other, has, inrecent years, been investigated in several experimental, theoretical,and computational studies. Those studies, however, primarily consideredthe limit of very small particle loadings (usually less than 3–5%).In this paper, we adapt our earlier formalism combining self-consistentfield theory (SCFT) for polymers with density functional theory (DFT)for the particles; the modified formalism explicitly incorporatesthe grafted chains into SCFT. We then perform several simulationsto study the dependence of morphology on the length and density ofgrafted chains as well as the nanoparticle loading. The results arein qualitative agreement with predictions of earlier theories in thelimit of lower particle loadings and predict new morphologies (“bundlesof wires”) for the case of larger particle loadings. The methodcan be easily extended to more complex cases (for example, where thematrix and/or ligand itself is a blend or block copolymer). [ABSTRACT FROM AUTHOR]

For the first time, a single-piece, all-solid-state ion-selective electrode was fabricated with carbon black supporting platinum nanoparticles (PtNPs-CB) and a polymeric membrane. The PtNPs-CB, as an intermediate layer, was drop-casted directly on the solid substrate, and then an ionophore-doped solvent polymeric membrane was added in order to form a sensor. The performance of the newly developed electrodes was evaluated on the basis of potassium and nitrate ions. The stability of the electrical potential for the electrodes was examined by performing current-reversal chronopotentiometry, and the influence of the interfacial water film was assessed by the potentiometric aqueous-layer test. Fabricated potassium- and nitrate-selective electrodes displayed a Nernstian slope and several outstanding properties such as high long-term potential stability, potential repeatability, and reproducibility. [ABSTRACT FROM AUTHOR]

The aim of this work was to enhancethe efficiency of a photocatalyticprocess involving carbon black (CB)-modified ZnO nanoparticles usingan electrochemical process consisting of powdered activated carbon(PAC), carbon nanotubes (CNTs), and CB-polytetrafluoroethylene (PTFE)-coatedgas-diffusion cathode(GDC) to degrade Acid Red 18. Hydrogen peroxide generated by PAC-PTFE-,CNT-PTFE-, and CB-PTFE-coated GDC was 58.45, 100.9, and 112.3 μM,respectively. The efficiency of the combined process equipped withCB-PTFE-coated GDC was assessed as the function of different operationalparameters. With the increase of initial pH from 3 to 10, decolorizationefficiency decreased from 94.5% to 57.61%. Increasing the dye concentrationfrom 2 to 20 mg/L led to a decrease in the decolorization efficiencyfrom 100% to 50.45%. The increase of the current intensity from 30to 300 mA resulted in increasing decolorization efficiency from 37.45%to 95.31%. TOC analysis showed 51.13% mineralization of 10 mg/L dyesolution in 20 min. [ABSTRACT FROM AUTHOR]

Under closed-window driving conditions, the in-vehicle-to-outside (I/O) concentration ratio for traffic-related particulate pollutants ranges from nearly 0 to 1 and varies up to 5-fold across a fleet of vehicles, thus strongly affecting occupant exposures. Concentrations of five particulate pollutants (particle-bound polycyclic aromatic hydrocarbons, black carbon, ultrafine particle number, and fine and coarse particulate masses) were measured simultaneously while systematically varying key influential parameters (i.e., vehicle type, ventilation, and speed). The I/O ratios for these pollutants were primarily determined by vehicle air exchange rate (AER), with AER being mostly a function of ventilation setting (recirculation or outside air), vehicle characteristics (e.g., age and interior volume), and driving speed. Small (±0.15) but measurable differences in I/O ratios between pollutants were observed, although ratios were highly correlated. This allowed us to build on previous studies of ultrafine particle number I/O ratios to develop predictive models for other particulate pollutants. These models explained over 60% of measured variation, using ventilation setting, driving speed, and easily obtained vehicle characteristics as predictors. Our results suggest that I/O ratios for different particulate pollutants need not necessarily be measured individually and that exposure to all particulate pollutants may be reduced significantly through simple ventilation choices. [ABSTRACT FROM AUTHOR]

Aircraft black carbon (BC) emissions contribute to climate forcing, but few estimates of BC emitted by aircraft at cruise exist. For the majority of aircraft engines the only BC-related measurement available is smoke number (SN)—a filter based optical method designed to measure near-ground plume visibility, not mass. While the first order approximation (FOA3) technique has been developed to estimate BC mass emissions normalized by fuel burn [EI(BC)] from SN, it is shown that it underestimates EI(BC) by >90% in 35% of directly measured cases (R² = -0.10). As there are no plans to measure BC emissions from all existing certified engines-which will be in service for several decades-it is necessary to estimate EI(BC) for existing aircraft on the ground and at cruise. An alternative method, called FOX, that is independent of the SN is developed to estimate BC emissions. Estimates of EI(BC) at ground level are significantly improved (R² = 0.68), whereas estimates at cruise are within 30% of measurements. Implementing this approach for global civil aviation estimated aircraft BC emissions are revised upward by a factor of ~3. Direct radiative forcing (RF) due to aviation BC emissions is estimated to be ~9.5 mW/m², equivalent to ~1/3 of the current RF due to aviation CO2 emissions. [ABSTRACT FROM AUTHOR]

Natural organic matter (NOM) plays an important role in determining the fate and transport of iodine species such as iodide (I-) and iodate (IO3-) in groundwater system. Although NOM exists as diverse forms in environments, prior iodine studies have mainly focused on uptake processes of iodide and iodate to humic materials. This study was conducted to determine the iodide and iodate uptake potential for a particulate NOM (i.e., black carbon [BC]). A laboratory-produced BC and commercial humic acid were used for batch experiments to compare their iodine uptake properties. The BC exhibited >100 times greater uptake capability for iodide than iodate at low pH of ~3, while iodide uptake was negligible for the humic acid. The uptake properties of both solids strongly depend on the initial iodine aqueous concentrations. After uptake reaction of iodide to the BC, X-ray absorption fine structure spectroscopy results indicated that the iodide was converted to electrophilic species, and iodine was covalently bound to carbon atom in polycyclic aromatic hydrocarbons present in the BC. The computed distribution coefficients (i.e., Kd values) suggest that the BC materials retard significantly the transport of iodide at low pH in environmental systems containing even a small amount of BC. [ABSTRACT FROM AUTHOR]

Recent research has demonstrated that black carbons catalyze the transformation of a range of nitrated explosives sorbed to the carbon surfaces in the presence of sulfides. Although surface oxygenated functional groups, particularly quinones, and electrical conductivity have both been hypothesized to promote these reactions, the importance of these properties has not been tested. In this work, the importance of electrical conductivity was addressed by producing chars of increasing electrical conductivity via pyrolysis of wood shavings at increasing temperature. The reactivity of chars with respect to transformation of the explosive RDX in the presence of sulfides correlated with electrical conductivity. Oxygenated functional groups were apparently not involved, as demonstrated by the elimination of reactivity of an activated carbon after ozone treatment or sorption of model quinones to the activated carbon surface. Although RDX transformation correlated with char electrical conductivity, no RDX transformation was observed when RDX was physically separated from sulfides but electrically connected through an electrochemical cell. RDX transformation occurred in the presence of a surface-associated sulfur species. The correlation with char electrical conductivity suggests that sulfides are oxidized on carbon surfaces to products that serve as potent nucleophiles promoting RDX transformation. [ABSTRACT FROM AUTHOR]

High volume in situ surface water samples were collected from a tidal tributary of the Delaware Estuary using an Infiltrex sampling system equipped with a 1 μm particle filter and a XAD-2 resin column. Particulate and dissolved phase polychlorinated biphenyl (PCB) congeners were analyzed using high resolution gas chromatography/high resolution mass spectrometry to obtain detection levels in the femtograms per liter range. The data were fit to a four-phase equilibrium partitioning model including freely dissolved PCB, PCB bound to particulate organic carbon (POC), PCB bound to dissolved organic carbon (DOC), and PCB bound to black carbon (BC). Isotherms were assumed to be linear for POC and DOC and nonlinear for BC. The partition coefficient between BC and dissolved PCB was assumed to depend on the dihedral angle between the phenyl rings. Following parameter optimization, the correlation coefficient between the log of the modeled and measured apparent distribution coefficient Kp,app was 0.94, and the RMSE was 0.189 log units. Including BC in the model reduces the dissolved PCB phase concentration in the water column for all congeners, especially for the non-ortho and mono-ortho substituted congeners. [ABSTRACT FROM AUTHOR]