Browsing by Author "Shalaby A."

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    A Comparative Azeotropic Research on Combustion of Common Ternary Systems
    (2023-01-01) Abdelhafiz M.; Hussein A.K.; Naeim I.; Shalaby A.; Azazy A.; Saleh A.; Tolba S.; Elbeih A.
    Methyl Tertiary Butyl Ether (MTBE) and Methanol are effective fuel oxygenate that boost octane number, improve fuel performance, combustion behavior and minimize environmental pollutant emissions. In the petroleum business, however, their high-water solubility restricts their use in terms of fuel homogeneity loss. This work presents a full investigation map for the status of the phase diagram for the tertiary system of MTBE-methanol-water at different temperatures; 0, 40, and 70oC, and different pressures; 1.0 and 3.0 atm, based on different compositions. Furthermore, the thermodynamic coefficient, UNIFAC-LL, was linked to the Aspen plus Version 9. After validation of the software by the real experimental data, the software was used to complete the full map at all missing conditions. Pressure does not influence the occurrence of phase transitions, but the temperature has a minor effect on the LLE. The methanol concentration at which phase separation occurred dropped from 43% to 31.2% when the temperature was lowered from 70 to 40°C. With the use of simulation, the compositions at which phase separation occurs were also discovered. Last but not least, it was observed that the thermodynamic model (UNIFAC-LL) properly predicted the behavior of the methanol-water-MTBE ternary system with less than 3% inaccuracy in the binodal curve points. Consequently, a validated phase diagram is developed to accurately predict the physical state of the MTBE-methanol-water system at ant temperature, pressure, and mole fraction of each component. Hence, it guarantees the feasibility of using this tertiary system, as an effective octane booster additive, under severe working conditions.
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    A study of the effect of citric acid on the crystallinity of ZnO/TiO2 nanopowders
    (2013-12-17) Shalaby A.; Bachvarova-Nedelcheva A.; Iordanova R.; Dimitriev Y.
    It is well known that the citric acid is used as a chelating agent which forms poly (basic acid) chelates with the metal cations in a nano-powder synthesis route. The aim of this investigation is to study the influence of the citric acid on the crystallization process in obtaining ZnO/TiO2 nano-composites. Samples have been synthesized by the aqueous sol-gel method applying two different schemes with and without citric acid, respectively. Several compositions containing different TiO2 (10, 90 mol %) and ZnO (10, 90 mol %) amounts were investigated. The as-prepared powders were calcinated from 100 to 500°C. The phase formation and structural transformation at every step of the synthesis route were followed by X-ray phase analysis and IR spectroscopy and the obtained results were compared.
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    Synthesis and characterization of glass doped reduced graphene oxide
    (2015-01-01) Shalaby A.; Aleksandrov L.; Iordanova R.; Staneva A.; Dimitriev Y.
    Graphene is very attractive material which has high conductivity and good electrical properties. By using glass as a matrix to incorporate the graphene, it is possible to improve the conductivity and the electrical properties of the glass. In our previous study we synthesized composite material by adding of reduced graphene oxide (RGO) to silica. In this work we continue our experiments to synthesize a composite material on a glass basis in the PbO-ZnO-B2O3 system. The differential thermal analysis of the present glass showed that the glass transition temperature (Tg) is situated at ca 415°C. The synthesized glass was doped with 20 % of reduced graphene oxide (RGO). A mixture of glass with RGO was heated at different temperature values for different time taking into consideration the glass transition temperature. The characterization is performed by X-ray phase analysis, DTA and SEM analysis. It was found according to the XRD results that graphene was kept inside the glass matrix till 600°C.