Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides
An adequate account of the hydrolytic properties of Cr3+ and Ni2+ allows setting the conditions for homogeneous nucleation of layered Ni(II)-Cr(III) double hydroxides; water exchange and hydrolysis rate constants indicate that, at very high rates of base dosing, formation of heteronuclear Cr(III)-Ni...
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todo:paper_00219797_v309_n1_p72_Jobbagy2023-10-03T14:25:12Z Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides Jobbágy, M. Blesa, M.A. Regazzoni, A.E. Chromium hydroxide Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Chromium alloys Dangling bonds Hydrolysis Microwaves Nucleation Precipitation (chemical) Urea Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Nickel alloys carbon dioxide chromium hydroxide hydroxyl group nickel water aging article chemical stress crystal hydrolysis microwave radiation particulate matter polymerization precipitation priority journal synthesis urea cycle water temperature An adequate account of the hydrolytic properties of Cr3+ and Ni2+ allows setting the conditions for homogeneous nucleation of layered Ni(II)-Cr(III) double hydroxides; water exchange and hydrolysis rate constants indicate that, at very high rates of base dosing, formation of heteronuclear Cr(III)-Ni(II) hydroxo species should prevail over precipitation of active Cr(OH)3. This is realized by the urea method under microwave-assisted hydrothermal conditions. This approach yields crystalline Ni1-xCrx(OH)2(CO3)x/2ṡnH2O (x ≈ 0.32 - 0.36) in less than 5 min at 453 K; higher degrees of crystallinity are obtained at higher temperatures and/or longer aging times. Formation of Ni(II)-Cr(III) LDHs upon microwave-assisted hydrothermal aging of freshly coprecipitated Ni(OH)2 + Cr(OH)3 mixtures takes longer, due to a different operating mechanism. The implications of the advanced rationale for the design of synthesis procedures are stressed. It is proposed that homogeneous nucleation of Ni(II)-Cr(III) LDHs involves the edge-on condensation of planar heteronuclear Cr(III)-Ni(II) hydroxo trimers. Ordered aggregation of primary particles leads to the final platelet crystals, a process that involves the exchange of CO2-3 ions dangling at the crystallites' edges by bridging OH-. © 2007 Elsevier Inc. All rights reserved. Fil:Jobbágy, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219797_v309_n1_p72_Jobbagy |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Chromium hydroxide Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Chromium alloys Dangling bonds Hydrolysis Microwaves Nucleation Precipitation (chemical) Urea Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Nickel alloys carbon dioxide chromium hydroxide hydroxyl group nickel water aging article chemical stress crystal hydrolysis microwave radiation particulate matter polymerization precipitation priority journal synthesis urea cycle water temperature |
| spellingShingle |
Chromium hydroxide Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Chromium alloys Dangling bonds Hydrolysis Microwaves Nucleation Precipitation (chemical) Urea Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Nickel alloys carbon dioxide chromium hydroxide hydroxyl group nickel water aging article chemical stress crystal hydrolysis microwave radiation particulate matter polymerization precipitation priority journal synthesis urea cycle water temperature Jobbágy, M. Blesa, M.A. Regazzoni, A.E. Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| topic_facet |
Chromium hydroxide Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Chromium alloys Dangling bonds Hydrolysis Microwaves Nucleation Precipitation (chemical) Urea Homogeneous precipitation Hydrotalcites Layered double hydroxides Nickel hydroxide Nickel alloys carbon dioxide chromium hydroxide hydroxyl group nickel water aging article chemical stress crystal hydrolysis microwave radiation particulate matter polymerization precipitation priority journal synthesis urea cycle water temperature |
| description |
An adequate account of the hydrolytic properties of Cr3+ and Ni2+ allows setting the conditions for homogeneous nucleation of layered Ni(II)-Cr(III) double hydroxides; water exchange and hydrolysis rate constants indicate that, at very high rates of base dosing, formation of heteronuclear Cr(III)-Ni(II) hydroxo species should prevail over precipitation of active Cr(OH)3. This is realized by the urea method under microwave-assisted hydrothermal conditions. This approach yields crystalline Ni1-xCrx(OH)2(CO3)x/2ṡnH2O (x ≈ 0.32 - 0.36) in less than 5 min at 453 K; higher degrees of crystallinity are obtained at higher temperatures and/or longer aging times. Formation of Ni(II)-Cr(III) LDHs upon microwave-assisted hydrothermal aging of freshly coprecipitated Ni(OH)2 + Cr(OH)3 mixtures takes longer, due to a different operating mechanism. The implications of the advanced rationale for the design of synthesis procedures are stressed. It is proposed that homogeneous nucleation of Ni(II)-Cr(III) LDHs involves the edge-on condensation of planar heteronuclear Cr(III)-Ni(II) hydroxo trimers. Ordered aggregation of primary particles leads to the final platelet crystals, a process that involves the exchange of CO2-3 ions dangling at the crystallites' edges by bridging OH-. © 2007 Elsevier Inc. All rights reserved. |
| format |
JOUR |
| author |
Jobbágy, M. Blesa, M.A. Regazzoni, A.E. |
| author_facet |
Jobbágy, M. Blesa, M.A. Regazzoni, A.E. |
| author_sort |
Jobbágy, M. |
| title |
Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| title_short |
Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| title_full |
Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| title_fullStr |
Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| title_full_unstemmed |
Homogeneous precipitation of layered Ni(II)-Cr(III) double hydroxides |
| title_sort |
homogeneous precipitation of layered ni(ii)-cr(iii) double hydroxides |
| url |
http://hdl.handle.net/20.500.12110/paper_00219797_v309_n1_p72_Jobbagy |
| work_keys_str_mv |
AT jobbagym homogeneousprecipitationoflayeredniiicriiidoublehydroxides AT blesama homogeneousprecipitationoflayeredniiicriiidoublehydroxides AT regazzoniae homogeneousprecipitationoflayeredniiicriiidoublehydroxides |
| _version_ |
1782028903809810432 |