Approximately 15 Mt/year of solid by-products (fly ash, bottom ash) are being produced by the lig... more Approximately 15 Mt/year of solid by-products (fly ash, bottom ash) are being produced by the lignite combustion in West Macedonia and Peloponnesus in Greece. The utilization of lignite byproducts, which are atmospheric dust components, is demanded to be significantly increased in the future. Potential environmental applications of these or some of these, by-products would make them a resource rather than a waste. In order to use fly ash as a resource, we synthesized TiO2-fly ash nanocomposites in two different mass ratios (70%–30% and 80%–20% respectively). The nanocomposites were prepared using fly ash from Megalopoli (Peloponnese) by depositing TiO2 in the form of anatase on the fly ash components using titanium isopropoxide as a precursor under mild hydrothermal conditions at 180 °C. Mineral as well as amorphous phase composition, particle morphology and physical properties of the prepared nanocomposites were characterized by XRD, SEM, SEM-EDS and N2-sorption/desorption isotherm...
ABSTRACT Two chromium-doped Raney nickel catalysts have been prepared from Al-Ni-Cr alloys where ... more ABSTRACT Two chromium-doped Raney nickel catalysts have been prepared from Al-Ni-Cr alloys where Cr was introduced in such a way as to substitute for nickel in the Ni2Al3 intermetallic phase. In comparison with the undoped catalysts, the BET and metallic surface areas remain little affected but more aluminium is retained after etching. X.P.S. shows that aluminium and nickel are in the metallic state whereas chromium is completely oxidized. Very large amounts of chromium are found on the surface, which suggests migration of chromium to the surface during leaching. Analytical electron microscopy indicates that the local chromium concentration is not perfectly uniform. Electron probe microanalysis of the precursor alloy reveals the segregation of part of chromium in a separate phase. These results are evaluated in the framework of the available literature data on the microstructure of Raney nickel catalysts.
The mechanism of retention of vanadium oxo-species at the “titanium oxide/aqueous solution” inter... more The mechanism of retention of vanadium oxo-species at the “titanium oxide/aqueous solution” interface was investigated over a wide pH range (4-9) and V(V) solution concentration (10-5-2×10-2 M) by combining equilibrium deposition experiments, potentiometric titrations, microelectrophoresis and “proton–ion” titration curves. It was inferred that the adsorbed V(V) oxo-species are retained inside the compact layer of the interface through hydrogen/coordinative bonds forming very probably innersphere complexes with the titania surface groups.
... An increase in the calcination temperature from 110 to 300 or 600 C results in the formation ... more ... An increase in the calcination temperature from 110 to 300 or 600 C results in the formation of alkaline earth molybdenum compounds via a surface reaction of the molybdenum(VI) species with M(NOa)2 and/or ... on Catalysis, Lund, October 1979, CWK Gleerup, Lund, 1981, p. 85 ...
Approximately 15 Mt/year of solid by-products (fly ash, bottom ash) are being produced by the lig... more Approximately 15 Mt/year of solid by-products (fly ash, bottom ash) are being produced by the lignite combustion in West Macedonia and Peloponnesus in Greece. The utilization of lignite byproducts, which are atmospheric dust components, is demanded to be significantly increased in the future. Potential environmental applications of these or some of these, by-products would make them a resource rather than a waste. In order to use fly ash as a resource, we synthesized TiO2-fly ash nanocomposites in two different mass ratios (70%–30% and 80%–20% respectively). The nanocomposites were prepared using fly ash from Megalopoli (Peloponnese) by depositing TiO2 in the form of anatase on the fly ash components using titanium isopropoxide as a precursor under mild hydrothermal conditions at 180 °C. Mineral as well as amorphous phase composition, particle morphology and physical properties of the prepared nanocomposites were characterized by XRD, SEM, SEM-EDS and N2-sorption/desorption isotherm...
ABSTRACT Two chromium-doped Raney nickel catalysts have been prepared from Al-Ni-Cr alloys where ... more ABSTRACT Two chromium-doped Raney nickel catalysts have been prepared from Al-Ni-Cr alloys where Cr was introduced in such a way as to substitute for nickel in the Ni2Al3 intermetallic phase. In comparison with the undoped catalysts, the BET and metallic surface areas remain little affected but more aluminium is retained after etching. X.P.S. shows that aluminium and nickel are in the metallic state whereas chromium is completely oxidized. Very large amounts of chromium are found on the surface, which suggests migration of chromium to the surface during leaching. Analytical electron microscopy indicates that the local chromium concentration is not perfectly uniform. Electron probe microanalysis of the precursor alloy reveals the segregation of part of chromium in a separate phase. These results are evaluated in the framework of the available literature data on the microstructure of Raney nickel catalysts.
The mechanism of retention of vanadium oxo-species at the “titanium oxide/aqueous solution” inter... more The mechanism of retention of vanadium oxo-species at the “titanium oxide/aqueous solution” interface was investigated over a wide pH range (4-9) and V(V) solution concentration (10-5-2×10-2 M) by combining equilibrium deposition experiments, potentiometric titrations, microelectrophoresis and “proton–ion” titration curves. It was inferred that the adsorbed V(V) oxo-species are retained inside the compact layer of the interface through hydrogen/coordinative bonds forming very probably innersphere complexes with the titania surface groups.
... An increase in the calcination temperature from 110 to 300 or 600 C results in the formation ... more ... An increase in the calcination temperature from 110 to 300 or 600 C results in the formation of alkaline earth molybdenum compounds via a surface reaction of the molybdenum(VI) species with M(NOa)2 and/or ... on Catalysis, Lund, October 1979, CWK Gleerup, Lund, 1981, p. 85 ...
Uploads
Papers by C. Kordulis