2/2015
The preparation and characterization of mesophase from coal tar pitch
This work was aimed at preparation of mesophase from coal tar pitch at different final temperatures. Mesophase was characterized by optical microscopic analysis, thermal analysis and Raman spectroscopy. From the results is evident, that the occurrence of predominantly isotropic homogeneous mass corresponds to lower values of temperatures of maximum oxidation velocity, the occurence of anisotropic texture corresponds to higher temperatures obtained from the DTG curves. Thermal analysis along with microscopic analy-sis confirms the trend of evolution of anisotropic texture depending on the rising temperature. More structured anisotropic texture was found in samples S and V. Both samples were also characterized by a higher distillation temperature for 70 vol.% of the pitch, and a higher viscosity at 100 °C.
Determination of Adsorbents Surface Area Using BET and DFT Methods
This paper is focused on the determination of surface area and pore size distribution for selected sorbents using BET and DFT methods. Adsorption processes are used in various fields, e. g. medicine, environmental protection, pharmaceutical industry. The carbonaceous materials and zeolites belong to most important adsorbents. These sorbents are used to the waste water and waste gas treatment, air drying, e.g. Adsorption process is also used to the biogas treatment very often (removal of sulphur compounds, siloxanes, water or carbon dioxide). Suitable adsorbent is chosen according to the adsorption capacity, selectivity, surface area, pore distribution, regeneration ability and cost. The obtained results showed that adsorbents based on activated carbon had highest surface area for both methods. Sorbents based on activated carbon and the combined adsorbent Envisorb B+ reached higher surface area for DFT method, there was a small difference between methods for silica materials, the activated carbon SC40 reached higher surface area for BET method and zeolites reached double surface area for DFT method. Using argon like adsorptive instead of nitrogen changed surface area for DFT method.
Fluidized bed incineration of dry stabilized sewage sludge from the wastewater treatment plant Brno
Effect of asphaltenes on structure of paraffin particles in crude oil
During the transportation and storage of crude oil at low temperatures, asphaltenes and paraffin compounds leave deposits that can cause problems and are expensive to remove. We investigated the effect of an increased amount of asphaltenes on the content and the size distribution of paraffin particles in samples of crude oil. Two sets of Azeri Light crude oil samples were used: the one set contained the standard asphaltene content of 0.035 wt.%; the other set was enriched with asphaltenes in propane asphalt form until the final asphaltene content was 0.35 wt.%. Both sets were thermally treated in an autoclave at different temperatures (40, 60, 80, 100 °C) for one hour to eradicate their thermal history. Afterwards, the samples were cooled down to 10 °C, and polarized light microscopy was used to record image data about paraffinic particles present in the samples. Image analysis confirmed our theory that the samples with a tenfold higher asphaltene content had significantly reduced amounts of paraffin particles, which were also smaller in size. The effect of asphaltene concentration on the paraffin particles was dependent on the applied temperature. Our results suggest that the asphaltene addition could affect the deposit formation in crude oil, as well as improving its low-temperature properties.