The carbonation kinetics of calcium hydroxide nanoparticles: A Boundary Nucleation and Growth description

Camerini, Rachel; Poggi, Giovanna; Chelazzi, David; Ridi, Francesca; Giorgi, Rodorico

doi:10.1016/j.jcis.2019.03.089

Cited by 40 publications

(23 citation statements)

References 90 publications

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“…where the term I 780 I 1087 (0) represents the relative starting concentration of emitting defective centres with respect to the amount of calcite crystals after the thermal treatment, and I 780 I 1087 (t) indicates the relative concentration of the defects at the instant t during the progressive carbonation process. By assuming a first order kinetic, in agreement with the model proposed by Camerini et al in [37], a rate equation can be found, as follows:…”

Section: Resultssupporting

confidence: 53%

Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

et al. 2020

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Calcium hydroxide, a crystal involved in the cycle of calcination and carbonation of calcium oxide, finds several applications from cultural heritage to the dentistry branch or to the construction industry. When excited at 1064 nm, Raman spectra of calcium hydroxide show a broad composite band peaked at about 780 cm−1, corresponding to 1170 nm. Since it is not observed with visible excitation, the origin of this band is debated, being assigned to some pre-existent luminescent impurities or some structural defect of the lime formed after the synthesis of the material. To shed light on the formation of this band, we synthetised the lime paste starting from pure calcite powders. The obtained fresh Ca(OH)2 samples did not show any band in the investigated range, irrespective of the laser excitation applied. A detailed analysis of the excitation and emission spectra in the near infrared region did not show the 1170 nm band, supporting the hypothesis of a post-synthesis origin. Thus, we carried out thermal treatments at different temperatures (90–500 °C) and under different environments (in air or under nitrogen flux) on synthesised fresh Ca(OH)2 powders. We also investigated the time evolution of the samples, monitoring the Raman spectra over 90 days after a specific treatment. The collected data support the hypothesis of a defect-related luminescence centre, whose formation depends on the temperature and environment of the treatment, which appears as a preferential site for the carbonation process of the calcium hydroxide. These results can be useful in the field of Cultural Heritage for dating purposes, and to determine the conservation state of Ca(OH)2 containing relics to prevent the possible activation of degradation processes.

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Section: Resultssupporting

confidence: 53%

Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

et al. 2020

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“…It is also an important material for Portland cement production and hardening [7,8]. Other researchers also reported on the effect of the surface area of Ca (OH)2 nanoparticles, on the carbonation kinetics for material construction; environmental and art preservation applications [9]. For all such advanced applications [1][2][3][4][5][6][7][8][9], the purity of the material matters a lot.…”

Section: Introductionmentioning

confidence: 99%

Influence of Impurity on the Properties of Chemically Synthesized Calcium Hydroxide

Harish¹,

Kumar²,

Kumari³

et al. 2021

J. Nano- Electron. Phys.

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Here we report synthesis and characterization of chemically synthesized calcium hydroxide (Ca(OH)2) with and without deliberate presence of NaNO3 as an impurity. Calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) is used as precursor and alkaline NaOH solution is used as precipitant to synthesize the Ca(OH)2 samples. The samples were characterized by XRD, FESEM, FTIR spectroscopy, DTA, TGA and UV-Vis spectroscopy techniques. From the UV-Vis spectroscopy results, it is found that the Ca(OH)2 with NaNO3 impurity has higher bandgap than the sample without NaNO3. The weight loss in TGA is also more for the Ca(OH)2 with impurity than the one for without impurity. The results are discussed in terms of composition formed during synthesis process.

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“…The main issues with such products include cracking during the drying due to gel shrinkage, temporary hydrophobic behavior, influence of the ambient humidity on the gel polymerization and poor chemical affinity between protectants and the stone substrates [12,13]. Inorganic consolidating products, such as calcium hydroxide, barium hydroxide and ammonium oxalate have good durability and compatibility with stone components [14][15][16]. By using these products, lower penetrability and subsequent poor strengthening effects should be considered.…”

Section: Introductionmentioning

confidence: 99%

Nano-materials enhanced protectants for natural stone surfaces

et al. 2021

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Most heritage buildings and monuments are constructed out of natural stones which suffer irrevocable degradation when undergoing wet weathering, bowing, and dissolution in outdoor conditions. Self-cleaning treatments are effective for stone protecting. Herein, nano-materials which provide enhanced protectants for Marble, Qingshi and Hedishi were prepared. Inherent microscale interstices and holes exist on polished natural stone surfaces. When treated by a commercial protectant, 101S, the surfaces were hydrophobic but not self-cleaning. Colloidal protectants were prepared by dispersion of Al2O3 and SiO2 nano-powder in 101S, respectively. Self-cleaning stone surfaces were achieved after treated by the protectants, meanwhile, the interstices and holes were reserved as much as possible. The principle of the as- prepared protectants is penetrating and crosslinking on the stone surfaces as well as the inner surfaces of the interstices and holes. The reserving of the micro interstices and holes is important since the breathability of the stones is remained. The self-cleaning surfaces showed good thermal stability below 250 °C. Meanwhile, changes of color and gloss of the treated stone surfaces are in the acceptable range.

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The carbonation kinetics of calcium hydroxide nanoparticles: A Boundary Nucleation and Growth description

Cited by 40 publications

References 90 publications

Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

Influence of Impurity on the Properties of Chemically Synthesized Calcium Hydroxide

Nano-materials enhanced protectants for natural stone surfaces

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