Submicron Carbon Particles Research Articles

Water-based Formuation of Inkjet Inks Using Jute Stick-derived Submicron Carbon Particles.

Biomass pyrolysis generates significant amount hazardous gases (such as CH4 , CO, and H2 ) which are counted as highly environmental pollutants. The utilization of these gases as fuel during pyrolysis could be a suitable choice for protecting the environment. Hence, we pyrolyzed biomass, jute sticks, using a customized pilot furnace, which recycled the generated gases as fuel. We further ball-milled the obtained carbon to make submicron carbon particles. The formation of submicron carbon particles was confirmed with field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, particle size analyzer, and thermogravimetric analysis. The zeta-potential studies confirmed the high negative surface zeta potential of the prepared submicron carbon that was due to its polar functional groups (-OH, COOH, and CO), which were confirmed by Fourier-transform infrared spectroscopy. These polar functional groups facilitate their dispersion in the aqueous solution of biocompatible ethylene glycol and isopropyl alcohol to form water-based environment-friendly inkjet inks. The printing test of the developed ink was performed using a Canon printer (PIXMA; model: G3420) and compared with the performance of commercial inkjet black ink. The results indicate that the performance of the developed inkjet ink is similar to the commercial one.

Water droplets embedded with nascent carbon particles hold higher photo-thermal efficiency than aged ones

Our experiments quantified that warming potential (photo-thermal efficiency, η) of smaller and fresh submicron carbon particles (CP) in water-droplet is 3–5 times higher compared to that of larger and aged CP. Also collocated sea-salt enhances this effect to a larger extent. Such effects are crucial for high altitude and coastal urban environments respectively. It is because scavenged CP can trigger heating leading to cloud burn-off affecting the precipitation events. Further climatic implications have been discussed. Indeed, the parameter η of CP should be considered as an important inclusion to various climate models in the context of regional climate change.

Electrically-Conductive Sub-Micron Carbon Particles from Lignin: Elucidation of Nanostructure and Use as Filler in Cellulose Nanopapers.

Carbon particles were produced from kraft lignin through carbonization of perfectly spherical, sub-micron beads obtained by aerosol flow. The structure of the resulting carbon particles was elucidated and compared to that derived from commercially available technical lignin powder, which is undefined in geometry. In addition to the smaller diameters of the lignin beads (<1 µm) compared to those of the lignin powder (100 µm), the former displayed a slightly higher structural order as revealed by X-ray diffraction and Raman spectroscopy. With regard to potential application in composite structures, the sub-micron carbon beads were clearly advantageous as a filler of cellulose nanopapers, which displayed better mechanical performance but with limited electrical conductivity. Compression sensing was achieved for this nanocomposite system.

Structure of carbon dendrites obtained in an atmospheric-pressure gas discharge

The influence of growth conditions on the carbon dendrite structure has been investigated. The threshold values of the ratio between electron temperature Te and kinetic temperature T of the gas near a needle electrode and of the discharge current density, which are necessary for dendritic growth, have been determined. It has been shown that the hexagonal structure of submicron carbon particles arises when a number of hydrocarbons are used to synthesize dendrites. It has been found that the degree of order in the carbon structure can be controlled by applying external actions at the stage of graphite particle nucleation. The characteristic frequencies of inertial actions that may be energetically appropriate must exceed 10 kHz.

Preparation and application of monodispersed mesoporous submicron carbon particles as a drug carrier

Monodispersed mesoporous carbon (MMPC) submicron carbon particles have been fabricated by co-spray drying of SBA-15 submicron particles and sucrose, followed by carbonization in a nitrogen environment and removal of the hard SBA-15 template in NaOH solution. The ratio of sucrose/SBA-15 used for the co-spray drying affected the integration and dispersibility of the obtained mesoporous carbon particles and sucrose/SBA-15 ratios at 1.0–1.5 resulted in monodispersed mesoporous carbon submicron particles. The surface properties of MMPC could be modified by treatment in nitric acid solution to create oxygen groups and thus increase wettability of MMPC powder. MMPC particles were used as drug carrier to enhance the dissolution rate of a poorly soluble drug, indomethacin (IDMC) via co-spray drying. The morphology of MMPC was not changed after drug loading as most IDMC molecules were encapsulated into its pore channels in amorphous state, which was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Due to the ordered mesoporous structure, the pore walls separate the IDMC particles and prevent recrystallization from happening. The amorphous IDMC/MMPC solid dispersion exhibited excellent stability under stress storage conditions of 40°C/75% RH for six months. The amorphous formulation contributed to the significantly enhanced dissolution rate of IDMC from solid dispersion.

Effects of CNTs on microstructure and hardness of laser welds of the CNT-reinforced magnesium composite

A magnesium composite reinforced with 1.3wt.% multiwall carbon nanotubes (MWCNTs) was welded using a CO2 laser. Abundant nanoscale and submicron carbon particles formed in the laser welds, owing to the coalescence of the reinforcing CNTs as the result of conjoint effect of laser irradiation and welding thermal annealing. Dense intra- and inter-granular carbon particles and carbon particle-enveloped equiaxed dendrites in the magnesium matrix constituted the characteristic weld microstructure. Lateral-irregular cellular growth originated from the weld fusion boundary and the carbon particle-enveloped equiaxed dendrites with substructure formed in the weld center. It is inferred that the CNTs affected the weld solidification mainly via retarding solidification growth rate. The gained weld hardening is primarily attributed to the local refined weld microstructure and locally denser carbon particles and MWCNTs. Lower laser fluence facilitated finer weld structure and less laser irradiation on the CNTs hence more hardening effect.

Heat transfer and growth of nano- and submicron particles of black carbon in nonequilibrium gas mixture. Experiment and simulation

It was shown experimentally and theoretically that heat transfer between carbon clusters and gas mixture substantially affects on growth of soot particles during ethylene pyrolysis in the shock tube. We used photoemission pyrometer for measuring of temperature of submicron carbon particles with microsecond temporal resolution, and bitmapped electron microscope for studying of geometrical parameters of primary carbon nanoparticles. Mathematical model of the nonisothermal carbon nanoparticles growth and results of its simulation is presented also.

Combustion of suspended fine solid fuel in air inside inert porous medium: A heat transfer analysis

Present work is a numerical analysis of combustion of submicron carbon particles inside an inert porous medium where the particles in form of suspension in air enter the porous medium. A one-dimensional heat transfer model has been developed using the two-flux gray radiation approximation for radiative heat flux equations. The effects of absorption coefficient, emissivity of medium, flame position and reaction enthalpy flux on radiative energy output efficiency have been presented. It is revealed that in porous medium the combustion of suspended carbon particles is similar to premixed single phase gaseous fuel combustion except the former has shorter preheating temperature zone length. Use of porous ceramic having high porosity and made of Al 2O 3 or ZrO 2 with stabilized flame position operated nearer to downstream end will ensure radiative output maximum and minimum at downstream and upstream end, respectively.

Behavior of Impurity Inclusions during Vacuum Distillation of Tellurium

Experimental data are presented on the effect of the Te evaporation rate on the efficiency of the removal of submicron carbon particles (major impurities in Te, present in amounts from 106to 5 × 108cm–3, depending on the purification procedure). By distilling a small amount of the melt, the effective separation coefficient was determined as a function of particle size. For 0.065- to 0.14-μm particles at a minimum evaporation rate of 3 × 10–7cm3 /(cm2s), the separation coefficient lies in the range 9–100. As the evaporation rate increases to 2.5 × 10–5cm3 /(cm2s), the separation coefficient drops to 2–8. Among the factors influencing the purification efficiency is the floating (inverse sedimentation) of submicron carbon particles in molten Te, observed experimentally upon long-term holding.

Thermal Modeling of a Small-Particle Solar Central Receiver

This paper presents a thermal model of a solar central receiver that volumetrically absorbs concentrated sunlight directly in a flowing gas stream seeded with submicron carbon particles. A modified six-flux radiation model is developed and used with the energy equation to calculate the three-dimensional radiant flux and temperature distributions in a cavity-type particle receiver. Results indicate that the receiver is capable of withstanding very high incident fluxes and delivering high temperatures. The receiver efficiency as a function of mass flow rate as well as the effect of particle oxidation on the temperature profiles are presented. [S0199-6231(00)00201-X]

Catalytic oxidation of submicron carbon particles and hydrocarbons from combustion aerosols

Catalytic oxidation of submicron carbon particles and hydrocarbons from combustion aerosols

Cosmic dust synthesis by accretion and coagulation

The morphology of grains grown by accretion and coagulation is revaled by a new laboratory method of synthesizing cosmic dust analogs. Submicron carbon particles, grown by accretion of carbon atoms from a gas, have a spherical shape with a cauliflower-like surface and an internal micro-structure of radial columns. This shape is probably common for grains grown by accretion at a temperature well below the melting point. Coagulated grains, consisting of spheres that collided to form irregular strings, were also synthesized. Another shape we produced had a bumpy non- spherical morphology, like an interplanetary particle collected in the terrestrial stratosphere. Besides these isolated grains, large spongy aggregates of nanometer-size particles were also found for various experimental conditions. Grains were synthesized using ions to sputter a solid target, producing an atomic vapor at a low temperature. The ions were provided by a plasma, which also provided electrostatic levitation of the grains during their growth. The temporal development of grain growth was studied by extinguishing the plasma after various intervals.

Observations of particle layers levitated in a radio-frequency sputtering plasma

Submicron carbon particles are grown in an argon radio-frequency (rf) sputtering plasma with graphite electrodes. In situ laser light scattering revealed particles levitated in the plasma in stratified layers, which were often thinner than 0.5 mm. Under some conditions, the number of layers was very large. These layers are grouped into clouds. In a pure argon plasma, there is one cloud near the sheath edge above the lower electrode, while adding SF6 results in additional particle clouds near the upper electrode and in the glow region. The different layers appear to separate particles according to size, with the heaviest in the lowest layer. During several hours of plasma operation, the layers collapsed and grew again into more stratified layers. The influence of parameters, such as gas pressure, rf power, electrode separation, and gas mixture was investigated. Scanning electron microscopy revealed that the particles were multisized spheres with a cauliflowerlike surface. Some of the particles were found to be coagulated, due to collisions within the plasma.

Effects of UV light irradiation on propane in an argon plasma

It has been shown that propane conversion into acetylene, by propane cracking in an argon plasma, is increased when the reaction site is irradiated with UV light in the range 220–400 nm. The reactions were carried out between 4500 and 6400 K. A model is outlined following which the propane conversion increase at 6400 K (40%) is tied up to energy absorption by acetylene in the lower wavelengths range (220–250 nm). Also, a combined adsorption-photochemical process, related to precursors and submicron carbon particles, could be responsible for the yield increase observed at 5400 K (45%), around 365.0 nm.