Papers by Keyword: Cerium

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Authors: Kishor Kumar Keekan, Jayesh C. Jalondhara
Abstract: Aspergillus niger PSSG8 is assisted bioleaching of monazite to recover the constituent metals were investigated. Bioleaching was carried out using Bromfield (BM1/10P & BM-P) and sucrose media (SM1/10P & SM-P) with different levels of Phosphate under rotary and stationary conditions. The growth of the A. niger PSSG8 significantly reduced the media pH to acidic. However, the media pH changed later in rotary shake flasks and were stable in roux bottles. A similar trend was observed for ORP. ORP increased as leaching progressed, but in rotary shake flasks ORP started decreasing after 15 days in Bromfield and 30 days in sucrose media. Fungal growth was maximum in SM when comparing to BM. The reduction and the omission of phosphate in both media did not significantly influence the culture parameters including the yield of biomass. ICP-AES analysis of leach liquor showed highest recovery of cerium (Ce) (1419 µg/L in BM-P) and thorium (Th) (182 µg/L in SM1/10P) in rotary conditions when comparing to the stationary conditions (229 µg/L Ce in BM 1/10P & 159 µg/L in SM-P). Reduction in the metal concentration was observed in the rotary shake flasks after 15 days of incubation. It was due to the biosorption of released metals by the fungal mycelium. Uranium was not detected in any of the media tested. SEM studies of the partially bioleached and control mineral particles show no changes in the surface features.
Authors: Nur Azmah Nordin, Saeed Farahany, T. Abubakar, Esah Hamzah
Abstract: Owing to its beneficial material properties, Al-Mg2Si in-situ composite has recently received wide attention and application in the manufacture of automotive and aerospace components. Melt treatment of the in-situ composite with the addition of Ce has resulted in a change in the primary and eutectic Mg2Si phases to refined morphology, which would be expected to improve the mechanical properties of the composite. Characteristic parameters of Mg2Si particles have been investigated via thermal and microstructural analysis. This has revealed that the addition of 0.8wt.% Ce produced optimum refinement effects on Mg2SiP because the coarse structure has been changed to a polygonal shape and reduced in size. Similarly, the flake-like morphology of Mg2SiE has been transformed into a rod-like or fibre form in addition to reduction of the eutectic cell area. The result also showed an increase in nucleation temperature TN of Mg2SiP while depressed for Mg2SiE, which also corresponds to the refinement morphology effect.
Authors: Jana Mikulová, Sylvie Rossignol, Jacques Barbier Jr., Charles Kappenstein, Daniel Duprez
Abstract: Sol-gel Zr0.1Ce0.9O2 and Zr0.1(Ce0.75Pr0.25)O2 mixed oxides and coprecipitated pure ceria CeO2 displaying the fluorine type structure have been used as platinum or ruthenium catalysts’ supports for catalytic wet air oxidation (CWAO) of aqueous solution of acetic acid (78 mmol.L-1). These catalysts were prepared by conventional impregnation (5 wt-%) from platinum and ruthenium precursor salts or by exchange (~2 wt-%) in the case of ruthenium. A screening of catalysts in CWAO at 200°C under 2 MPa was performed and reveals that the best platinum catalyst is supported on pure ceria displaying large surface. For ruthenium catalysts, the highest conversion after 3 hours of reaction has been reached by the Ru/Zr-Ce-O system.
Authors: Salmiah Jamal Mat Rosid, Wan Azelee Wan Abu Bakar, Rusmidah Ali
Abstract: The methanation reaction is a promising method for the purification of natural gas, in which the acid gases of CO2, is eliminated by catalytic conversion. The advantage of catalytic technology is the utilization of CO2 present in the production of methane gas. The used of alumina supported cerium oxide as the based catalyst in CO2/H2 methanation reaction have been investigated in this research by using manganese as the dopant and ruthenium as the co-dopant via wet impregnation technique. The series of cerium oxide catalysts were calcined at 400 °C for 5 hours had been prepared at the screening stage. Then, the catalysts were optimized by different calcination temperatures and different based oxide loadings. The potential catalysts of Ru/Mn/Ce (5:35:60)/Al2O3 calcined at 700 °C gave 100 % of CO2 conversion by using FTIR and yielded about 24 % of CH4 respectively at reaction temperature of 400 °C. X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) showed that the supported catalysts were amorphous in structure. FESEM analysis illustrated the surface of the catalysts were covered with small and dispersed spherical particles. EDX analysis revealed that there was 1.02 % reduction of Ru in the Ru/Mn/Ce (5:35:60)/Al2O3 used catalysts compared to fresh catalysts. Meanwhile NA analysis showed that Ru/Mn/Ce (5:35:60)/Al2O3 catalysts attained surface area of 143.10 m2/g respectively.
Authors: Yan Ling Lu, Shi Guo Du, Yi Guo, Yan Kun Chen, Qing Hong
Abstract: With different means of soaking treatment, simple cerium conversion coating, KH560 silane conversion coating, cerium silane conversion coating and silane cerium conversion coating are formulated. SEM, EDS, Tafel and EIS measurements were adopted as the analysis approaches, and organic resin is coated on the conversion coating surface for the salt spray test, so as to check mainly how much the corrosion resistant capabilities could be improved if conversion coating is applied to the magnesium alloy. The result shows that the cerium silane conversion coating and silane cerium conversion coating have a higher self-corrosion potential, lower corrosion current density, improve the binding force between the organic coating and magnesium alloy matrix more effectively, thus enhance dramatically the corrosion resistant protection capabilities for the whole coating applied on the magnesium alloy matrix.
Authors: M. Raukas, S.A. Basun, W. Van Schaik, U. Happek, William M. Yen
Authors: G.M. Liu, L. Yang, F. Yu, Ji Hong Tian, Shu Wang Duo, N. Du
Abstract: In order to improve corrosion resistance of galvanized steel, a novel cerium-phytic acid passivation treatment was studied. The process of cerium-phytic acid passivation on galvanized steel was optimized. The corrosion resistance of cerium-phytic passivated samples was tested by dropping test and weight loss test. The electrochemical behaviors of cerium, phytic acid and cerium-phytic acid passivated samples in 0.5 mol/L NaCl solution were investigated by polarization curve and AC impendence spectroscopy, respectively. The corrosion equivalent circuit established according to impedance characteristics. The corrosion current density of the samples were treated by cerium and phytic acid was 8.52 × 10-5 A/cm2 and 9.39 × 10-5 A/cm2, respectively, However, the samples were passivated by cerium-phytic acid the corrosion current density decreased to 1.76 × 10-5 A/cm2, respectively. The test results showed that cerium-phytic acid passivated samples exhibited better corrosion resistance than that of cerium or phytic acid passivated sample under the same test conditions.
Authors: A.S. Anasyida, Zuhailawati Hussain, Abdul Razak Daud, M.J. Ghazali
Abstract: The purpose of this work is to understand the phases formation and lattice parameter changes with addition 0.6 to 2.7 wt.% in Al-Si-Mg-Ce cast alloy. Al-Si-Mg-Ce eutectic and hypoeutectic cast alloy were prepared by conventional casting technique. The alloys were investigated by using optical microscope, Scanning electron microscope (SEM) and X-Ray diffractometry (XRD). The addition of Ce resulted in precipitation of Al4Ce in eutectic cast alloy and CeMg2Si2 in hypoeutectic cast alloy. The lattice parameter of Al increases with increase in Ce content wheareas lattice parameter of Si phase decreases as the Ce content increases.
Authors: H.S. Isaacs, A.J. Aldykiewics Jr.
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