61 research outputs found
Valorization Iron Oxide (Fe2O3) obtained from recycling Hydrochloric Acid (HCl) in pickling line of steel galvanization process.
No full textSynthesis of CoAl2O4 by double decomposition reaction between LiAlO2 and molten KCoCl3
No full textSubmicronic CoAl2O4 powders were prepared by double decomposition reaction between solid LiAlO2 and molten KCoCl3 at 500 ◦C for 24 h. The reaction mechanism involves the dissolution of LiAlO2 shifted by the precipitation of CoAl2O4 until complete transformation and the reaction leads to powders with a very homogeneous chemical composition. The powders obtained were mainly characterized by XRD, FTIR, ICP, X.EDS, electron microscopy and diffraction and diffuse reflexion. The blue pigments obtained exhibit a high thermic stability allowing their use for the colouring of ceramic tiles
Investigation of the reactivity of AlCl3 and CoCl2 toward molten alkali-metal nitrates in order to synthesize CoAl2O4
No full textCobalt aluminate CoAl2O4 powder, constituted of nano-sized crystallites, is prepared, involving the reactivity of AlCl3 and CoCl2 with molten alkali-metal nitrates. The reaction at 450 °C for 2 h leads to a mixture of spinel oxide Co3O4 and amorphous γ-Al2O3. It is transformed into the spinel oxide CoAl2O4 by heating at 1000 °C. The powders are mainly characterized by XRD, FTIR, ICP, electron microscopy and diffraction, X-EDS and diffuse reflection. Their properties are compared to those of powders obtained by solid state reactions of a mechanical mixture of chlorides or oxides submitted to the same thermal treatment
Reactivity of aluminum sulfate and silica in molten alkalimetal sulfates in order to prepare mullite
No full textWith the aim of preparing mullite, reactions between aluminum sulfate and silica in appropriate proportions and molten sulfate media M2SO4 (M=Na and/or K) were performed at different temperatures. The powders obtained were characterized by XRD, FT-IR, SEM and TEM. The reactivity was the same in Na2SO4 and (K,Na)2SO4 media. The best results in terms of yield (98.3%) and weight of mullite produced (95%) were obtained in Na2SO4 at 950 °C. The mullite phase exhibits an acicular morphology (75×0.75 μm) and a specific surface area close to 20 m2/g. In K2SO4 medium, a potassium alumino silicate is formed as well as mullite
Purple nanometrics pigments based on cobalt-doped manganese molybdate: Synthesis, characterization, structural, thermal, optical, colorimetric and chemical properties
No full textInternational audienceThis work is related to the characterization of nanometrics materials of the βMnMoO 4-βCoMoO 4 system, prepared by co-precipitation and sol-gel routes from the corresponding metal salts. The structural, morphological and colorimetric characteristics of the obtained powders were studied using thermogravimetric and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), infrared and Raman spectroscopy, scanning electron microscopy (SEM) and colorimetry (CIE-L * a * b * system). The surface specific area was calculated using the Brunauer-Emmett-Teller analysis (BET) in the adsorption/desorption isotherm. The X-ray diffraction patterns highlighted the formation of a continuous solid solution Mn 1-x Co x MoO 4 (0 ≤ x ≤ 1) of monoclinic symmetry (C 2 /m) isotype to β-MnMoO 4 and this regardless of the synthetic route adopted. FTIR and Raman spectroscopy analysis showed that the chemical bonds' nature in the Mn 1-x Co x MoO 4 compounds corresponded to the strong MoO -Mo, MoO and CoO -Mo vibrational modes. The micrographs (SEM) highlighted the form of nanorods with sizes ranging from 10 to 200 nm for compositions x = 0.3 and x = 0.6, prepared by co-precipitation. The specific surface area measurements indicated that the powders obtained by the sol-gel process present lower values than those prepared by co-precipitation, regardless the cobalt substitution rate. The specific surface area of the purple nanoscale powder (x = 0.6) obtained by co-precipitation was about 7.52 m 2 /g. Colorimetric parameters analysis of the powders heat treated at 1100 °C showed that the degree of the component (-b *) was significant for compositions x = 0.6, regardless of the synthesis method adopted
Influence du milieu fondu Na2SO4, sur la décomposition de gels précurseurs de la mullite
No full textNous avons préparé des gels de mullite par neutralisation de solutions de sulfate d’aluminium et de silicate de sodium dans un rapport A1203/Si02 = 1,5. Les gels obtenus ont été séchés à 120°C pendant 12 heures, puis décomposés, d’une part par calcination à l’air à 950°C pendant 6 heures et d’autre part, par traitement thermique dans un bain fondu de sulfate de sodium toujours à 950°C pendant 6 heures. Les différentes poudres obtenues ont été caractérisées par diffraction de rayons X, par spectrométrie infrarouge à transformée de Fourrier (FTIR) et par microscopies à balayage (MEB) et à transmission (MET). L’étude de paramètres tels que la nature du traitement thermique et le pH montre que le processus de mullitisation est favorisé quand les précurseurs sont traités en milieu sel fondu et à pH acide
Molten Salt Synthesis and Characterization of CuIn(1-x)GaxS2 (x ≤0.3) Nanoparticles
No full textSolid solutions CuIn(1-x)GaxS2 (x ≤ 0.3)were synthesized, with a yield of 70%, by reaction in molten KSCN at 400°C for 24h of CuCl2, InCl3 and GaCl3 with a ratio KSCN/Cu=15. The homogeneous solid solutions obtained are formed of nano-sized grains (70–100nm), with a specific surface area of 6.5 m2/g and a band gap between 1.5 and 1.8 eV
Influence of chelating agent on the morphological properties of α-CuMoO4 powder synthesized by sol–gel method
No full textInternational audienceIn this work, we have synthesized precursor gels of copper molybdate with various chelating agents (glycine, polyacrylic acid, citric acid). After heating at adequate temperatures, the obtained precursors led to the pure phase α-CuMoO4, whose morphology and grain size depend on the chemical nature of the chelating agent used
Green nanoceramic pigments based on cobalt chromite doped with Al: Synthesis, characterisation and colour performance
No full textInternational audienc
Molten Salt Synthesis and Characterization of CuIn(1-x)GaxS2 (x ≤0.3) Nanoparticles.
No full textSolid solutions CuIn(1-x)GaxS2 (x ≤ 0.3)were synthesized, with a yield of 70%, by reaction in molten KSCN at 400°C for 24h of CuCl2, InCl3 and GaCl3 with a ratio KSCN/Cu=15. The homogeneous solid solutions obtained are formed of nano-sized grains (70–100nm), with a specific surface area of 6.5 m2/g and a band gap between 1.5 and 1.8 eV
- …
