Carbonaceous Nanoparticles Research Articles

Facile preparation of magnetic carbonaceous nanoparticles for Pb 2+ ions removal

Magnetic carbonaceous nanoparticles were prepared by a facile two-step solution phase thermal synthesis. Magnetic nanoparticles (MNPs) with size less than 100 nm were first generated from FeCl 3 in a solvothermal reaction. The size could be significantly reduced to approximately 30 nm when 1,6-hexanediamine was employed in the reaction solution to functionalize the surface of MNPs with amine. Both the plain and amine-functionalized MNPs (MH) were effectively encapsulated in the carbonaceous shell by hydrothermal treatment in 0.5 M glucose solution. The saturation magnetization of MH decreased significantly from 70 to 25 emu/g after carbonaceous shell was formed. The as-prepared magnetic carbonaceous nanoparticles (MH@C) carries a negative surface charge (−30 mV) at neutral pH and has a point of zero charge (PZC) at pH 2. The carbonaceous shell not only can protect the magnetic nanoparticles (MNP) from the corrosive environment but also possesses a high adsorption capacity towards Pb(II). The adsorption isotherm at room temperature can be well-fitted by Langmuir model with a maximum adsorption capacity of 123 mg/g.

Simulation of Nanoparticle Permeation through a Lipid Membrane

A metric of nanoparticle toxicity is the passive permeability rate through cellular membranes. To assess the influence of nanoparticle morphology on this process, the permeability of buckyball-sized molecules through a representative lipid bilayer was investigated by molecular-dynamics simulation. When C 60 was compared with a prototypical opened C 60 molecule and a representative combustion-generated particle, C 68H 29, the calculated free-energy profiles along the permeation coordinate revealed a sizable variation in form and depth. The orientation of the anisotropic molecules was determined by monitoring the principal axis corresponding to the largest moment of inertia, and free rotation was shown to be hindered in the bilayer interior. Diffusion constant values of the permeant molecules were calculated from a statistical average of seven to 10 trajectories at five locations along the permeation coordinate. A relatively minor variation of the values was observed in the bilayer interior; however, local resistance values spanned up to 24 orders of magnitude from the water layer to the bilayer center, due primarily to its exponential dependence on free energy. The permeability coefficient values calculated for the three similarly sized but structurally distinct nanoparticles showed a significant variance. The use of C 60 to represent similarly sized carbonaceous nanoparticles for assessments of toxicity is questioned.

Natural Organic Matter Removal by Adsorption onto Carbonaceous Nanoparticles and Coagulation

Nanoparticles have emerged as promising adsorbents for water purification. In this study, nanoscale carbon black was employed to remove natural organic matter (NOM) from water in the presence and absence of coagulation. Standard Suwannee River NOM was employed as the targeted pollutant. In the absence of coagulation, more than 60% NOM removal was achieved by carbon black adsorption. A higher hydrogen ion concentration (pH) (3–5) was favorable for NOM removal. More than 35% NOM was removed by carbon black adsorption in the first 20 min, and the adsorption of NOM onto carbon black occurred within about 2 h. Proper stirring was essential for the mixture of NOM and carbon black, while insufficient stirring or overstirring decreased NOM removal efficiency. When low dosages of coagulants were used in combination with carbon black at pH 6–7, the removal efficiency of NOM increased significantly. Depending on the coagulant, the sequencing of adsorption and coagulation can be important. Almost 90% NOM was removed ...

One‐Step Hydrothermal Synthesis of Nitrogen‐Doped Nanocarbons: Albumine Directing the Carbonization of Glucose

We present a simple and green one-step pathway towards nitrogen-doped carbon nanostructures with controlled mesoporosity through hydrothermal treatment of glucose in the presence of model proteins. Performing the reaction with different amounts of egg white ovalbumin protein (OvA), carbonaceous nanoparticles or continuous nanosponges with high specific surface areas can be efficiently produced. The nitrogen content of the structures is rather high (up to 8 wt%) and can be kept constant up to 950 degrees C, while oxygen elimination and graphitization of the carbon material occurs. We demonstrate here that sustainable natural resources can be efficiently used in the synthesis of pure high-potential nanomaterials.

Indications of IL1β, IL18 and VEGF cascade in maintenance of homeostasis following transient pulmonary inflammation due to carbon nanoparticle (CNP) challenge in mice

Aims: Carbonaceous nanoparticles possess an emerging source of human exposure. The pulmonary inflammation caused by deposited nanoparticles is a key event for their adverse health effects. Epidemiological studies suggest that individuals with favourable lung physiology are at lower risk for particulate matter associated respiratory diseases. We selected a mouse strain C3H/HeJ (C3) with robust lung physiology and exposed it to moderately toxic carbon nanoparticles (CNP) to study the elicited pulmonary inflammation and its resolution. Methods: 5µg, 20µg and 50µg CNP were intratracheally (i.t.) instilled in C3 mice. Inflammation was assessed using histology, broncheoalveolar lavage (BAL) analysis and by a panel of 62 protein markers to analyze the molecular response. Results: 24h after instillation of CNP, C3 mice exhibited a typical dose response, with the lowest dose (5µg) representing the 'no effect level' as reflected by polymorphonuclear leucocyte (PMN) influx, and BAL/lung concentrations of pro-inflammatory cytokines and proteins. Accordingly time course assessment of the inflammatory response was performed after 3 and 7days with 20µg CNP instilled animals. Compared to 24h, BAL PMN counts were significantly decreased at day 3 and by day 7 complete resolution of PMN influx was observed. We have identified protein markers related to acute response and also for time course response in lung and BAL. After complete resolution of PMN influx on day7, protein concentrations of FGA, CRP, APCS, CCL5, CCL9, FGF2, CCL11, vWF, XCL1, CXCL5, THPO, VEGFA, IL1B, IL18, CSF1, EDN1, CCL3, CCL4, F3 and CD40L were significantly elevated in the lung and BAL. These factors are involved in a closely regulated molecular cascade with IL1β/IL18at the upstream and FGF2/EDN1/VEGF at the downstream. BAL-protein concentration and histological analysis did not reveal any evidence of tissue injury in 20µg CNP instilled animals. Conclusion: Considering the role of VEGF, FGF2 and EDN1 in lung development and morphogenesis together with the lack of any evident tissue damage we suggest a protective/homeostatic machinery is activated to counter the CNP challenge as a precautionary measure.

Aerosol Imaging with a Soft X-Ray Free Electron Laser

Lasers have long played a critical role in the advancement of aerosol science. A new regime of ultrafast laser technology has recently be realized, the world's first soft x-ray free electron laser. The Free electron LASer in Hamburg, FLASH, user facility produces a steady source of 10 femtosecond pulses of 7–32 nm x-rays with 1012 photons per pulse. The high brightness, short wavelength, and high repetition rate (> 500 pulses per second) of this laser offers unique capabilities for aerosol characterization. Here we use FLASH to perform the highest resolution imaging of single PM2.5 aerosol particles in flight to date. We resolve to 35 nm the morphology of fibrous and aggregated spherical carbonaceous nanoparticles that existed for less than two milliseconds in vacuum. Our result opens the possibility for high spatial- and time-resolved single particle aerosol dynamics studies, filling a critical technological need in aerosol science.

Bottom-up multi-step approach to study the relations between the structure and the optical properties of carbon soot nanoparticles

In this paper we study the relations between the structure of approximately spherical carbonaceous nanoparticles and their frequency dependent dielectric susceptibility in the optical and near-UV domain. Because the nanoparticles are defined atomistically, the set of atomic point dipoles is distributed on an irregular grid and we cannot use traditional discrete-dipole approximation (DDA) codes. We thus developed an approximate multi-step methods that allowed us to discuss scattering of light by both carbonaceous nanoparticles and aggregates of these nanoparticles. We find that the dielectric susceptibility of these nanoparticles is highly dependent on the type of chemical units used to construct the particles, but almost independent of their distribution in the various shells of the nanoparticle.

Study of carbonaceous nanoparticles in premixed C 2H 4–air flames and behind a spark ignition engine

Nanoparticle size distributions and their concentrations were studied in atmospheric premixed ethylene/air flames using photo ionization mass spectrometry (PIMS) and total organic carbon (TOC) calibration supplemented by differential mobility analysis (DMA). Focus of this study is the evolution of nanoparticles as a function of height above burner (HAB) and of the C/O ratio of the unburned gases. It was found that especially particles of the cluster type exhibit a sharp concentration drop by more than two orders of magnitude within a narrow C/O window which is close to the sooting threshold. Using DMA a decline by two orders of magnitude was found. These results suggest that at best only small concentrations of nanoparticles should be formed significantly below the sooting threshold. As these conditions prevail in a homogeneously charged IC engine no or only very small nanoparticle emissions are expected in the exhaust gas. This was indeed found for a small Otto engine driving a power generator unit. Using flame nanoparticle profiles as standard, absolute concentrations for their emissions could be deduced. These data were supported by additional DMA measurements. The calibration using TOC did not completely match the one based on the condensation particle counter of the DMA apparatus.

Pathway focused protein profiling indicates differential function for IL-1B, -18 and VEGF during initiation and resolution of lung inflammation evoked by carbon nanoparticle exposure in mice

BackgroundCarbonaceous nanoparticles possess an emerging source of human exposure due to the massive release of combustion products and the ongoing revolution in nanotechnology. Pulmonary inflammation caused by deposited nanoparticles is central for their adverse health effects. Epidemiological studies suggest that individuals with favourable lung physiology are at lower risk for particulate matter associated respiratory diseases probably due to efficient control of inflammation and repair process. Therefore we selected a mouse strain C3H/HeJ (C3) with robust lung physiology and exposed it to moderately toxic carbon nanoparticles (CNP) to study the elicited pulmonary inflammation and its resolution.Methods5 μg, 20 μg and 50 μg CNP were intratracheally (i.t.) instilled in C3 mice to identify the optimal dose for subsequent time course studies. Pulmonary inflammation was assessed using histology, bronchoalveolar lavage (BAL) analysis and by a panel of 62 protein markers.Results1 day after instillation of CNP, C3 mice exhibited a typical dose response, with the lowest dose (5 μg) representing the 'no effect level' as reflected by polymorphonuclear leucocyte (PMN), and BAL/lung concentrations of pro-inflammatory proteins. Histological analysis and BAL-protein concentration did not reveal any evidence of tissue injury in 20 μg CNP instilled animals. Accordingly time course assessment of the inflammatory response was performed after 3 and 7 days with this dose (20 μg). Compared to day 1, BAL PMN counts were significantly decreased at day 3 and completely returned to normal by day 7. We have identified protein markers related to the acute response and also to the time dependent response in lung and BAL. After complete resolution of PMN influx on day 7, we detected elevated concentrations of 20 markers that included IL1B, IL18, FGF2, EDN1, and VEGF in lung and/or BAL. Biological pathway analysis revealed these factors to be involved in a closely regulated molecular cascade with IL1B/IL18 as upstream and FGF2/EDN1/VEGF as downstream molecules.ConclusionConsidering the role of VEGF, FGF2 and EDN1 in lung development and morphogenesis together with the lack of any evident tissue damage we suggest a protective/homeostatic machinery to be associated in lungs of stable organisms to counter the CNP challenge as a precautionary measure.

Estimating the relevance of engineered carbonaceous nanoparticle facilitated transport of hydrophobic organic contaminants in porous media

Naturally occurring nanoparticles (NP) enhance the transport of hydrophobic organic contaminants (HOCs) in porous media. In addition, the debate on the environmental impact of engineered nanoparticles (ENP) has become increasingly important. HOC bind strongly to carbonaceous ENP. Thus, carbonaceous ENP may also act as carriers for contaminant transport and might be important when compared to existing transport processes. ENP bound transport is strongly linked to the sorption behavior, and other carbonaceous ENP-specific properties. In our analysis the HOC–ENP sorption mechanism, as well as ENP size and ENP residence time, was of major importance. Our results show that depending on ENP size, sorption kinetics and residence time in the system, the ENP bound transport can be estimated either as (1) negligible, (2) enhancing contaminant transport, or (3) should be assessed by reactive transport modeling. One major challenge to this field is the current lack of data for HOC–ENP desorption kinetics.

Molecular Dynamics Simulation Study of a Pulmonary Surfactant Film Interacting with a Carbonaceous Nanoparticle

This article reports an all-atom molecular dynamics simulation to study a model pulmonary surfactant film interacting with a carbonaceous nanoparticle. The pulmonary surfactant is modeled as a dipalmitoylphosphatidylcholine monolayer with a peptide consisting of the first 25 residues from surfactant protein B. The nanoparticle model with a chemical formula C 188H 53 was generated using a computational code for combustion conditions. The nanoparticle has a carbon cage structure reminiscent of the buckyballs with open ends. A series of molecular-scale structural and dynamical properties of the surfactant film in the absence and presence of nanoparticle are analyzed, including radial distribution functions, mean-square displacements of lipids and nanoparticle, chain tilt angle, and the surfactant protein B peptide helix tilt angle. The results show that the nanoparticle affects the structure and packing of the lipids and peptide in the film, and it appears that the nanoparticle and peptide repel each other. The ability of the nanoparticle to translocate the surfactant film is one of the most important predictions of this study. The potential of mean force for dragging the particle through the film provides such information. The reported potential of mean force suggests that the nanoparticle can easily penetrate the monolayer but further translocation to the water phase is energetically prohibitive. The implication is that nanoparticles can interact with the lung surfactant, as supported by recent experimental data by Bakshi et al.

Optical properties of carbonaceous nanoparticles produced in sputtering discharges

In this work, the authors report on the optical properties of carbonaceous nanoparticles produced in argon sputtering dc discharges. These particles are the result of a nucleation-condensation mechanism in gas phase and form porous particulates with a mean diameter greater than 20nm. The resulting powderlike deposit, which can be collected in the chamber, is analyzed in terms of an effective medium approximation that allows the determination of their optical constants. These parameters are then used in a simple application of the Lorenz-Mie theory, in combination with a laser-extinction experiment, to provide the particle density in the plasma.

Combustion-formed nanoparticles

The processes by which carbonaceous nanoparticles are produced from combustion of liquid and gaseous fuels are reviewed. The focus of the paper is on the formation and properties of nanoparticles in laboratory laminar, premixed and diffusion flames and on the most popular methods of sampling and detection of these particles. Particle chemical nature is analyzed from data obtained by several measurement techniques. Measurements characterizing nanoparticles in the exhausts of practical combustion systems such as engines and commercial burners are also reported. Two classes of carbonaceous material are mainly formed in combustion: nanoparticles with sizes in the range 1–5nm, and soot particles, with sizes from 10 to 100nm. Nanoparticles show unique chemical composition and morphology; they maintain molecular characteristics in terms of chemical reactivity, but at the same time exhibit transport and surface related phenomena typical of particles. The emission of these particles contributes to atmospheric pollution and constitutes a serious health concern. A simplified modeling analysis is used to show how the growth of aromatics and the chemical nature of the particles depend on temperature and radical concentration distributions encountered in flames.

Anomalous Self-Aggregation of Carbon Nanoparticles in Polar, Nonpolar, and Binary Solvents

Polydisperse preparations of multicarbon nanoparticles were observed to undergo anomalous time-dependent self-association leading to the formation of nanoclusters in carbon tetrachloride (nonpolar and hydrophobic solvent, high solubility), water (polar and nonhydrophobic solvent, low solubility), and ethanol−water binary solvents (polarity and hydrophobicity dependent on ethanol concentration, marginal solubility) at room temperature (20 °C). The association kinetics in CCl4, water, and binary solvents could be described through the Smoluchowski aggregation model where the average cluster diameter dav was found to scale with time, t as dav ∼ tβ, where β = 0.58 ± 0.07, 0.45 ± 0.05, 0.57 ± 0.08, and 0.65 ± 0.09 for CCl4, water, and 45% (v/v) and 70% (v/v) ethanol binary solvents, respectively. The corresponding mass fractal dimensions, df of these clusters were df = 1/β = 1.72 for CCl4, 2.22−2.95 for water (depending on salt concentration), and 1.75 and 1.54 for 45% (v/v) and 70% (v/v) ethanol binary solvents, respectively. The intensity of scattered light, Is(t) did not exhibit such universal behavior: for the CCl4 sample, Is(t) ∼ tα with α = 0.65, whereas, for all other solvents, a linear time-dependent increase was observed mimicking a Derjaguin−Landau−Verwey−Overbeek (DLVO) type growth mechanism. The β values obtained for clusters dispersed in CCl4 and the binary solvents implied cluster−cluster aggregation while the same in water behaved like diffusion limited aggregation (DLA) clusters. The physical morphology of these clusters was observed through high-resolution transmission electron microscopy (HRTEM) studies. UV spectroscopy data showed characteristic solute−solvent interactions. The electrophoretic mobility studies in the binary solvents indicated interesting polyampholyte-type behavior of these clusters. The results taken together indicate the specific role played by hydrophobicity in solubilization of carbonaceous nanoparticles.

Environmental materials research: opportunities and challenges in China

Increased awareness of the social and economic costs and the health and ecological impacts of environmental pollution have created demands for pollution control and environmental remediation. Of vital importance to meeting these demands is the development of cost-effective environmental materials. The underpinning science for advances in, and potential uses of, representative environmental materials, including carbonaceous materials, clay minerals, mesoporous silica and nanoparticles of metals and metal oxides, are reviewed, along with their advantages and limitations. To judge the success or otherwise of their applications, three general criteria are proposed. The scientific, economic, regulatory and educational challenges that need to be considered in future research on environmental materials and the development of their cost-effective uses are discussed.

Single walled carbon nanotubes induce indirect cytotoxicity by medium depletion in A549 lung cells

The ability of two types of single walled carbon nanotubes (SWCNT), namely Arc Discharge (AD) and HiPco ® single walled carbon nanotubes, to induce an indirect cytotoxicity in A549 lung cells by means of medium depletion was investigated. The nanotubes were dispersed in a commercial cell culture medium and subsequently removed by centrifugation and filtration. Spectroscopic analysis confirmed the removal of the nanotubes and showed differing degrees of alteration of the composition of the medium upon the removal of the nanotubes. The ability to induce an indirect cytotoxic effect by altering the medium was evaluated using two endpoints, namely the Alamar Blue (AB) and the Clonogenic assay. Exposure of the A549 cells to the depleted medium which had previously contained carbonaceous nanoparticles, revealed significant cytotoxicity for both endpoints employed. The results presented demonstrate that single walled carbon nanotubes can induce an indirect cytotoxicity by alteration of cell culture medium (in which they have previously been dispersed) which potentially results in a false positive toxic effect being observed in cytotoxicity studies.

Direct Synthesis of Carbon-Rich Composite Sub-microtubes by Combination of a Solvothermal Route and a Succeeding Self-Assembly Process

A new self-assembly route at room temperature to produce carbon-rich composite sub-microtubes with large aspect ratios through aging a solution containing amorphous carbon nanoparticles with functional groups produced by a solvothermal carbonization of glucose in pyridine solution has been reported. The driving force of the latter assembly phenomena can be the affinities of different solutions for the functional groups grafted on the carbonaceous nanoparticles. This method shows the possibility to produce similar tubular structures by taking advantage of moderate intermolecular forces among the chemically grafted carbon nanoparticles.

Optical properties of soot nanoparticles

In this paper, the dipole–dipole approximation is used to characterize the dynamical electromagnetic properties of two types of carbonaceous nanoparticles modelling the basic constituents of aircraft soot particles. The corresponding polarizability per unit volume is then compared with the one calculated for equivalent defect-free structures and with the one resulting from a continuum model. It is found that the polarizability per unit volume strongly depends on the details of the structure of the nanoparticle, and that this dependence could be used to discriminate between different carbonaceous particles using optical scattering experiments in the visible or near-UV domain.

Measurements of Nanoparticles of Organic Carbon and Soot in Flames and Vehicle Exhausts

We measured the size distribution and UV extinction spectra of carbonaceous nanoparticles present in the size range of 1-100 nm in the exhausts of 2004 model gasoline and diesel powered vehicles and compared the results with those obtained in premixed flames. In addition to soot particles, nanoparticles of organic carbon (NOC) were measured in the emissions of these test vehicles in significant number and mass concentrations. The number and mass concentration of NOC was higher than soot in gasoline vehicle emissions. In diesel emissions, NOC had a higher number concentration than soot in terms of number concentration, but in terms of mass concentration, soot was higher than NOC. The size (1-3 nm) and extinction spectra in the UV-visible (strong in the UV and transparent in the visible) of macromolecules/nanoparticles collected in water samples from the vehicles are similar to those measured in laboratory hydrocarbon-air flames, suggesting that these nanoparticles are formed in hydrocarbon combustion reactions. We advance the hypothesis that NOC in vehicle emissions are produced by high-temperature combustion processes and not by low-temperature condensation processes.

Dust plasma analogue for interstellar 217.5 nm extinction

The new ultraviolet (UV) extinction measurements of carbonaceous nanoparticles in the range from 140 nm to 260 nm are presented. The plasma polymerized hydrocarbon nanoparticles were already proposed as a new astro analogue, which describe the infrared (IR) extinction spectra in an excellent way. We use the same particles to find the possible carrier of the 'mysterious' UV 217.5 nm extinction 'bump' of interstellar media (ISM).