- Effect of organic acids precursors on the morphology and size of ZrO2 nanoparticles for photocatalytic degradation of Orange G dye from aqueous solutions
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Zirconium oxide nanoparticles were prepared by precipitation from different organic acid precursors (oxalic, tartaric, citric, succinic, malic, maleic and malonic) and ignition at 750 °C. The as-prepared samples were characterized by XRD, FT-IR, UV–Vis an
- Ibrahim, Islam M.,Moustafa, Moustafa E.,Abdelhamid, Mohamed R.
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- Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry
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A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0 M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 × 10-6 to 5.0 × 10-4 M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is ε520 nm = 1.16 × 103 L mol-1 cm-1 and the detection limit for oxalic acid is 0.815 μg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.
- Zhai, Qing-Zhou
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- A substrate-versatile catalyst for the selective oxidation of light alkanes I. Reactivity
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The reactivity of niobium and pyridine-exchanged molybdophosphoric and molybdovanadophosphoric acid catalysts were studied for the selective oxidation of light alkanes. The catalysts were active and selective for the selective oxidation of propane and n-butane over a wide temperature range and under both hydrocarbon-rich and oxygen-rich reaction conditions. For the selective oxidation of n-butane to maleic acid, the presence of vanadium did not significantly influence the reactivity. In contrast, for the selective oxidation of propane to acrylic acid, the presence of vanadium significantly affected the selectivity to the desired product. The selective oxidation of propane also led to the production of maleic acid as a major product under certain reaction conditions. For the selective oxidation of n-butane, the productivity of the catalyst was greater than that of vanadium phosphorous oxide. With propane, the productivity of acrylic acid exceeded that of MoVNbTeOx. The catalysts are also active for selective oxidation of other substrates, e.g., ethane, isobutane, and toluene.
- Holles, Joseph H.,Dillon, Christopher J.,Labinger, Jay A.,Davis, Mark E.
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- On the activity of ZrO2 prepared by different methods
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Zirconia samples with different structures (monoclinic, tetragonal or a mixture of the two) was prepared by different methodologies, including a novel procedure involving the precipitation of an oxalate precursor and the formation of pure tetragonal ZrO2. The different precursors obtained by varying the preparative procedure (ex oxychloride, ex oxalate, and ex gel) were studied by means of differential thermal analysis and thermogravimetric analysis under air and under N2, while the final oxides were characterized by BET, porosimetry and XRD analysis. The surface acid-base properties of the different oxides were assessed via the catalytic decomposition isopropanol. A prevalence of acid sites found for the ex-oxalate ZrO2 seems to justify the different mechanism of chain growth observed in the carbonylation of methanol with CO/H2 mixtures in the presence of Rh.
- Kaddouri,Mazzocchia,Tempesti,Anouchinsky
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- A oxalic acid zirconium crystal and preparation method
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The invention provides a zirconium oxalate crystal and a preparation method thereof. A low-price inorganic zirconium salt, a regulator and oxalic acid are crystallized under solvothermal conditions to obtain the zirconium oxalate crystal. The obtained zirconium oxalate crystal has high crystallinity. The obtained zirconium oxalate crystal is of micron particle size, and is uniform in particle size and convenient for separation. The zirconium oxalate provided by the invention can be used as a chemical adsorbent and used for preparing a tetragonal-phase ZrO2 precursor.
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Paragraph 0013; 0014
(2017/08/25)
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- Nanocrystalline oxalate/carbonate precursors of Ce and Zr and their decompositions to CeO2 and ZrO2 nanoparticles
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The oxalate and carbonate precursors of cerium and zirconium have been prepared using reverse micelles as nanoreactors. Cerium oxalate precursor on thermal decomposition leads to a mixture of nanorods and nanoparticles of cerium oxide (nanoparticles of 10 nm and nanorods with 7 nm diameter and 30 nm length). Cerium oxide with crystallite size of 10 nm was obtained from cerium carbonate precursor. Monodispersed nanoparticles of zirconia with an average size of 3-5 and 12 nm were obtained from the oxalate and carbonate precursor, respectively. Detailed dielectric properties of sintered discs of nanocrystalline ceria and zirconia have been studied with variation of frequency and temperature.
- Vaidya, Sonalika,Ahmad, Tokeer,Agarwal, Suman,Ganguli, Ashok K.
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p. 863 - 869
(2008/10/09)
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