The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate...The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate of Eu was initially low, but significantly increased at pH>4. The sorption density of Eu species on a silica surface was ～1.58×10 -7 mol/m2 when the dissolved Eu species were completely sorbed onto silica-water interfaces at pH=～5.8. The sorbed Eu species at pH<6 is aquo Eu 3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH<5, but may be sorbed as an inner-sphere bidentate complex at 5<pH<6, due to the decrease of N H 2O to ～6 at pH=6. At pH=6-8.5, Eu(OH)+ 2, Eu(CO 3)+ and Eu(CO 3)- 2 formed in the solutions, and Eu(CO 3)+ is dominant at pH=～7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes.展开更多
The sorption of Eu species onto nano-size silica-water interfaces is investigated at pH range of 1―8.5 and the initial Eu concentrations (CEu) of 2 × 10?5, 2 × 10?4 and 2 × 10?3 M using fluorescence sp...The sorption of Eu species onto nano-size silica-water interfaces is investigated at pH range of 1―8.5 and the initial Eu concentrations (CEu) of 2 × 10?5, 2 × 10?4 and 2 × 10?3 M using fluorescence spectroscopy. The sorption rate of Eu is initially low, but significantly in-creases at pH > 4. For the initial CEu of 2 × 10?5, 2 × 10?4 and 2 × 10?3 M, the dissolved Eu spe-cies are completely sorbed onto silica-water interfaces at pH = 4.75, ~5.8 and 6.6, respectively, with the respective sorption densities of ~1.58 × 10?8, 1.58 × 10?7 and 1.58 × 10?6 mol/m2. The sorbed Eu species at pH < 6 is aquo Eu3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH < 5, but may be sorbed as an inner-sphere bidentate complex at 5 < pH < 6, due to the decrease of the NH2O to ~6 at pH = 6. At pH = 6 – 8, Eu(OH)2+, Eu(CO3)+ and Eu(CO3)2? form in the solutions, and Eu(CO3)+ is dominant at pH = ~7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes or multi-nuclear pre-cipitates.展开更多
The one-pot synthesis of a series of 1,2,4-triazines from the reactions of semicarbazide or thiosemi-carbazide with various α,β-dicarbonyl compounds under reflux conditions in a EtO H-H2O (9:1) mixture as solvent an...The one-pot synthesis of a series of 1,2,4-triazines from the reactions of semicarbazide or thiosemi-carbazide with various α,β-dicarbonyl compounds under reflux conditions in a EtO H-H2O (9:1) mixture as solvent and catalyzed by nano-sized silica supported FeCl3(FeCl3@SiO 2) was investigat-ed. The FeCl3 content of the catalyst was measured by atomic absorption to get the adsorption ca-pacity. The reactions gave high yields of the product and the catalyst was easily separated and re-used for successive reaction runs without significant loss of activity.展开更多
文摘The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate of Eu was initially low, but significantly increased at pH>4. The sorption density of Eu species on a silica surface was ～1.58×10 -7 mol/m2 when the dissolved Eu species were completely sorbed onto silica-water interfaces at pH=～5.8. The sorbed Eu species at pH<6 is aquo Eu 3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH<5, but may be sorbed as an inner-sphere bidentate complex at 5<pH<6, due to the decrease of N H 2O to ～6 at pH=6. At pH=6-8.5, Eu(OH)+ 2, Eu(CO 3)+ and Eu(CO 3)- 2 formed in the solutions, and Eu(CO 3)+ is dominant at pH=～7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes.
文摘The sorption of Eu species onto nano-size silica-water interfaces is investigated at pH range of 1―8.5 and the initial Eu concentrations (CEu) of 2 × 10?5, 2 × 10?4 and 2 × 10?3 M using fluorescence spectroscopy. The sorption rate of Eu is initially low, but significantly in-creases at pH > 4. For the initial CEu of 2 × 10?5, 2 × 10?4 and 2 × 10?3 M, the dissolved Eu spe-cies are completely sorbed onto silica-water interfaces at pH = 4.75, ~5.8 and 6.6, respectively, with the respective sorption densities of ~1.58 × 10?8, 1.58 × 10?7 and 1.58 × 10?6 mol/m2. The sorbed Eu species at pH < 6 is aquo Eu3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH < 5, but may be sorbed as an inner-sphere bidentate complex at 5 < pH < 6, due to the decrease of the NH2O to ~6 at pH = 6. At pH = 6 – 8, Eu(OH)2+, Eu(CO3)+ and Eu(CO3)2? form in the solutions, and Eu(CO3)+ is dominant at pH = ~7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes or multi-nuclear pre-cipitates.
基金the Bu-Ali Sina University, Hamedan 6517838683 Iran for the financial support of this work
文摘The one-pot synthesis of a series of 1,2,4-triazines from the reactions of semicarbazide or thiosemi-carbazide with various α,β-dicarbonyl compounds under reflux conditions in a EtO H-H2O (9:1) mixture as solvent and catalyzed by nano-sized silica supported FeCl3(FeCl3@SiO 2) was investigat-ed. The FeCl3 content of the catalyst was measured by atomic absorption to get the adsorption ca-pacity. The reactions gave high yields of the product and the catalyst was easily separated and re-used for successive reaction runs without significant loss of activity.
