Kinetic and Thermodynamic Studies of Silica Nanoparticle Dissolution

Rimer, Jeffrey D.; Trofymluk, Olga; Navrotsky, Alexandra; Lobo, Raúl F.; Vlachos, Dionisios G.

doi:10.1021/cm070708d

Cited by 110 publications

(160 citation statements)

References 52 publications

(111 reference statements)

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“…Both hydrated and dehydrated ACC are high-energy metastable phases and there is a big energetic driving force for their crystallization. This large energy difference between hydrated amorphous and dehydrated crystalline phases is similar to the energetics of amorphous oxides such as zirconia and silica (39,40). The surface energies of the amorphous oxide materials are significantly smaller than those of their crystalline counterparts, suggesting that small particle size could lead to thermodynamic stabilization of amorphous relative to crystalline nanoscale materials (41,42).…”

Section: Discussionmentioning

confidence: 68%

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Radha

Forbes

Killian

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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416

449

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Amorphous calcium carbonate (ACC) is a metastable phase often observed during low temperature inorganic synthesis and biomineralization. ACC transforms with aging or heating into a less hydrated form, and with time crystallizes to calcite or aragonite. The energetics of transformation and crystallization of synthetic and biogenic (extracted from California purple sea urchin larval spicules, Strongylocentrotus purpuratus) ACC were studied using isothermal acid solution calorimetry and differential scanning calorimetry. Transformation and crystallization of ACC can follow an energetically downhill sequence: more metastable hydrated ACC → less metastable hydrated ACC ⇒ anhydrous ACC ∼ biogenic anhydrous ACC ⇒ vaterite → aragonite → calcite. In a given reaction sequence, not all these phases need to occur. The transformations involve a series of ordering, dehydration, and crystallization processes, each lowering the enthalpy (and free energy) of the system, with crystallization of the dehydrated amorphous material lowering the enthalpy the most. ACC is much more metastable with respect to calcite than the crystalline polymorphs vaterite or aragonite. The anhydrous ACC is less metastable than the hydrated, implying that the structural reorganization during dehydration is exothermic and irreversible. Dehydrated synthetic and anhydrous biogenic ACC are similar in enthalpy. The transformation sequence observed in biomineralization could be mainly energetically driven; the first phase deposited is hydrated ACC, which then converts to anhydrous ACC, and finally crystallizes to calcite. The initial formation of ACC may be a first step in the precipitation of calcite under a wide variety of conditions, including geological CO 2 sequestration. amorphous calcium carbonate (ACC) | calorimetry | crystallization enthalpy | sea urchin larval spicules | synthetic and biogenic ACC

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Section: Discussionmentioning

confidence: 68%

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Radha

Forbes

Killian

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

416

449

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“…The acid pH at which silica is exposed when removing polyamide 6 does not dissolve it. Perhaps there may be small changes on its structure, but it can be concluded that they are not significant at all, in agreement with the reported amorphous silica dissolution rates at different pH conditions [147].…”

Section: Changes In Materials Due To the Scaffold Fabrication Processsupporting

confidence: 85%

“…1.3 are reversed to produce again silanol groups. More current works [147] evaluate the dissolution of crystalline and vitreous silicas immersed at different pH conditions. The conclusion one can extract is the possibility to dissolve the acid catalyzed sol-gel silica which this work deals with.…”

Section: Changes In Materials Due To the Scaffold Fabrication Processmentioning

confidence: 99%

Acrylate-silica polymer nanocomposites obtained by sol-gel reactions. Structure, properties and scaffold preparation.

Rodríguez¹,

Carlos²

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“…In situ microcalorimetry has been used to systematically study the thermochemical and thermokinetic properties of the synthesis process and crystal growth of rare-earth complexes [15][16][17]. This method has also been applied to the zeolite and silica system, and used to delineate the relationship between thermodynamic factors and changes in the solution chemistry and interface properties [18][19][20][21][22][23][24]. The formation mechanism of MCM-41 mesoporous silica was also investigated using microcalorimetry [25].…”

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confidence: 99%

Kinetic investigation of in situ growth of CdMoO4 nano-octahedra

Jiang

Fan

et al. 2011

Chin. Sci. Bull.

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CdMoO 4 nano-octahedra were grown in situ at room temperature by reverse-microemulsion. Energy evolution from this growth process was monitored using microcalorimetry. The microcalorimetric heat flow (MCHF) curve showed a characteristic endothermic peak for the initial reaction, and double discontinuous exothermic peaks for the subsequent crystal growth. Combined with complementary characterization techniques, the evolution of morphology and size of the CdMoO 4 nano-octahedra were correlated with the MCHF peaks. Calculations based on the microcalorimetric results at 298.15 K provided rate constants of 7.56×10 -5 s -1 for the reaction and nucleation process and 1.59×10 -4 s -1 for the crystallization process. Over the past decade, attention has focused on the preparation of nanomaterials with controlled sizes and morphologies [1-3], which are important in determining the properties of the materials. Unfortunately, real time growth mechanisms for this controlled synthesis remain unclear. Consequently, clarification of the aggregation pathways and thermodynamics of in situ growth of nanoparticles is critical. Several methods have been used to explore the aggregation pathways during crystal growth, such as classical crystallization kinetic theory [4], in situ electron microscopy [5][6][7], scanning tunneling microscopy [8,9], in situ ellipsometry [10], in situ synchrotron X-ray absorption [11], and quartz crystal microbalance in combination with in situ X-ray photoelectron spectroscopy [12]. However, these methods cannot be used to evaluate instantaneous information from the non-equilibrium growth of nanomaterials. Moreover, they are expensive, carried out under harsh conditions, lack universality, and do not provide information on energetics. Thus, alternative methods are required to determine the energy evolution during synthesis of nanomaterials. This information could be used to effectively control the *Corresponding author (email: huangzyhappy@163.com) size distribution, structure and growth directions of nanoparticles.Calorimetry is an effective method to measure the changes in heat associated with crystal growth [13,14]. The major advantage of this method is that the system will not be disturbed during measurements. Additionally, continuous and accurate recordings can be provided on energy evolution in the system. In situ microcalorimetry has been used to systematically study the thermochemical and thermokinetic properties of the synthesis process and crystal growth of rare-earth complexes [15][16][17]. This method has also been applied to the zeolite and silica system, and used to delineate the relationship between thermodynamic factors and changes in the solution chemistry and interface properties [18][19][20][21][22][23][24]. The formation mechanism of MCM-41 mesoporous silica was also investigated using microcalorimetry [25]. In addition, microcalorimetry has been used to determine standard molar enthalpies [26] and the surface and interface enthalpies [27]. It is therefore reasonable to apply calorime...

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Kinetic and Thermodynamic Studies of Silica Nanoparticle Dissolution

Cited by 110 publications

References 52 publications

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Acrylate-silica polymer nanocomposites obtained by sol-gel reactions. Structure, properties and scaffold preparation.

Kinetic investigation of in situ growth of CdMoO4 nano-octahedra

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