Desorption and re-adsorption of PAHS on aircraft soot surface

Polycyclic Aromatic Hydrocarbons (PAHs) in aircraft soot are capable to distribute in the gas phase and particulate phase in chemical transformations in the atmosphere. The desorption of PAHs from the soot surface is a preliminary step in the study of the reactivity of particulate PAHs. The desorption kinetics of PAHs are measured from soot samples to determine desorption rate constants for different PAHs as a function of temperature and the binding energies between PAHs and soot. The kinetics of degradation of particulate PAHs were studied in the flow reactor. The soot samples previously deposited on a Pyrex tube are introduced into the reactor along its axis and the concentrations of PAHs adsorbed on soot are determined by the High-Performance Liquid Chromatography (HPLC) as a function of the desorption time. The results show a correlation between the size of PAHs and the thermodynamics of desorption: with the PAHs have the same number of carbon atoms, their energies of desorption are very similar and increase with this number. The activation energies EA and the number of carbon atoms in PAHs have a linear correlation. It is consistent with the additivity of the laws Van der Waals. The similarity between the activation energies of desorption of PAHs and the corresponding sublimation enthalpies is consistent with the similarity between the graphitic structure of soot and the structure of PAHs.

Correlating Thermal Characteristics From Flow-Reactor Experiments With Primary Reference Fuel

An experimental investigation was conducted to correlate thermal characteristics with primary reference fuel (PRF) using an “isothermal” flow reactor. Objective of the investigation was to assess whether or not thermal characteristics measured in a radiant-heated flow reactor could serve as an indicator of fuel octane number. The experimental set-up consisted of a radiant furnace and a pyrex-tube test section inside. The pyrex tube was fitted with thermocouples alongside the tube wall. Four PRF compositions of iso-octane and n-heptane were considered: 0, 65, 85 and 100% of iso-octane by volume; noted as PRF0, 65, 85 and 100, respectively. The test conditions reported in the paper set the fuel-air mixture temperature to 180 °C at the inlet of the test section and the radian furnace temperature to 345 °C. The equivalence ratio was set in the range 0.93 to 2.0. For a pre-set PRF and equivalence-ratio condition, the experiments were run with fixed mixture velocities over the range 0.019 m/s to 0.400 m/s. Over the conditions tested, the thermocouples recorded two temperature oscillations along the flow reactor for each of PRF0, 65 and 85 mixtures. Both oscillation locations moved downstream when PRF number was increased and the two oscillation locations merged when PRF was set to 85. No temperature oscillations were recorded for experiments with PRF100 mixture. The results suggest that the temperature oscillation locations from the experiments using isothermal flow-reactors can be used to correlate fuel octane number.

Determination of ozone distribution in fish cold storage dedicated plasma ozone technology

Research on the distribution of ozone in a cold storage has been done. This cold storage is equipped with an ozone piping system. Ozone inserts to the cold storage was generated by dielectric barrier discharge plasma. The reactor is made of two stainless steel mesh wire cylindrical electrodes and a barried by a pyrex tube. The pipes are hollowed so that ozone can be distributed into cold storage. The distribution of ozone in cold storage is determined by placing a petri dish in twenty-four different points. Ozone that inserted to storage (10 cubic meters) with a capacity of 40 grams/hour. The inserting of ozone into cold storage was done with four different lengths of time wich are 30, 60, 90, and 120 minutes. Ozone distribution in storage was almost the same at each measurement points. The most influential in the distribution is the time. We found that the distribution of ozone into storage with average ozone concentration of 4.3, 6.3, 4.6, and 4.0 ppm with time 30, 60, 90, 120 minutes respectively. Futhermore, we also dissolve the ozone into the water in the tank in the same storage with temperature (2-8)0C. We found that the concentration of dissolved ozone in the water without samples was always greater than that of the existing fish and shrimp samples, with various dissolution times between (30-120) minutes at 30 minutes intervals. Cold storage dedicated ozone was used to store fish used to store tuna, milkfish and shrimp. With ozone immersion of fish in ozone-soluble water can maintain fish quality for 16 days.

Magnetic Property of á-Fe Nanoparticles Prepared by Solventless Thermal Decomposition Method

ABSTRACTNano sized α-Fe particle was synthesized by modified thermal decomposition method. It resulted in the higher saturation magnetization (Ms) almost equivalent to the value of bulk Fe power (Mbulk = 210 emu/g). To prepare Fe nanoparticles, the Fe2+-(oleate)2 complex was annealed at 400 J in pyrex tube and the prepared Fe3O4 nanoparticle was reduced to Fe crystal structure at 700 J with NaCl under Ar+H2 gas atmosphere and annealed again under high vacuum system of 10−5 torr. The crystallinity and structure of the Fe nanoparticle was investigated by powder X-ray diffraction (XRD). The shape and size was confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with coercivity and remanence from hysteresis loop by vibrating sample magnetometer (VSM)