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We investigate the conductivity of a composite of PANI-PAMPSA and PANI-PAMPSA with carbon particles by impedance spectroscopy. We establish that the addition of carbon particles to the PANI-PAMPSA composite leads to a significant rise in the conductivity over the entire range of frequencies studied (from 10 Hz to 5 MHz). Such increase in conductivity is very important for using the PANI-PAMPSA composite in solar energy. We propose an equivalent electrical circuit of the samples investigated. At low frequencies, the conductivity dependence on frequency indicates the hopping mechanism of the charge carrier transport. [ABSTRACT FROM AUTHOR]

Abstract: The behavior of carbon particles from 0.01 to diameters in natural convection flow field of air was numerically studied including the effect of the magnetic field and the Brownian motion. One thousand carbon particles were released randomly in a vertical cylindrical enclosure whose height is equal to its radius. The enclosure was heated from below and cooled from above to produce the bulk flow of the natural convection of air in the atmospheric condition. A coil with electric current was set coaxially at the enclosure bottom to produce a magnetic field. Sample computations are carried out for the enclosure of 3cm high and maximum magnetic field is 2.8T or less. The results show that the natural convection of air is enhanced by the magnetic field. With the increase in the magnetic strength, more particles go along the fluid streak lines. With the increase in the particle size, more particles get together at the vortex center and cluster. [Copyright &y& Elsevier]

Mass transfer in multiphase systems is one of the most studied topics in chemical engineering. However, in three-phase systems containing small particles, the mechanisms playing a role in the increased rate of mass transfer compared to two-phase systems without particles, are still not clear. Therefore, mass transfer measurements were carried out in a 2D slurry bubble column reactor (0.015×0.30×2.00 m3), a stirred tank reactor with a flat gas–liquid interface, and in a stirred tank reactor with a gas inducing impeller. The rate of mass transfer in these reactors was investigated with various concentrations of active carbon particles (average particle size of 30 μm), with electrolyte (sodium gluconate), and with combinations of these. In the bubble column, high-speed video recordings were captured from which the bubble size distribution and the specific bubble area were determined. In this way, the specific mass transfer area agl was determined separately from the mass transfer coefficient kl. Mechanisms proposed in literature to describe mass transfer and mass transfer enhancement in stirred tank reactors and bubble columns are compared. It is shown that the increased rates of mass transfer in the 2D bubble column and in the stirred tank reactor with the gas inducing impeller are completely caused by an increased gas–liquid interfacial area upon addition of carbon particles and electrolyte. It is suggested that an increased level of turbulence at the gas–liquid interface caused by carbon particles accounts for a smaller effective boundary layer thickness and an enhancement of mass transfer in the flat gas–liquid surface stirred tank reactor. However, for the carbon particles used in this study, it is rather unlikely that mass transfer enhancement takes place due to the well-known shuttle or grazing effect. [Copyright &y& Elsevier]