Complexation Mechanism of Dextrin with Metal Hydroxides

Raju, G Bhaskar; Holmgren, Allan; Forsling, Willis

doi:10.1006/jcis.1997.5332

Cited by 33 publications

(16 citation statements)

References 14 publications

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“…The FTIR spectra of the slaked lime putties (Figure b) showed a strong and sharp absorption band at 3642 cm –1 corresponding to the O–H stretching and an intense broad band at 442 cm –1 corresponding to the Ca–O stretch–bend motion. These bands are characteristic of portlandite . The small shoulder at ∼1630–1650 cm –1 , corresponding to the O–H bending, in addition to the broad band at 3457 cm –1 (ν OH ) are likely associated with H 2 O in ACC.…”

Section: Resultsmentioning

confidence: 94%

Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

et al. 2017

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Hydrated lime (Ca(OH)) is a vernacular art and building material produced following slaking of CaO in water. If excess water is used, a slurry, called lime putty, forms, which has been the preferred craftsman selection for formulating lime mortars since Roman times. A variety of natural additives were traditionally added to the lime putty to improve its quality. The mucilaginous juice extracted from nopal cladodes has been and still is used as additive incorporated in the slaking water for formulation of lime mortars and plasters, both in ancient Mesoamerica and in the USA Southwest. Little is known on the ultimate effects of this additive on the crystallization and microstructure of hydrated lime. Here, we show that significant changes in habit and size of portlandite crystals occur following slaking in the presence of nopal juice as well as compositionally similar citrus pectin. Both additives contain polysaccharides made up of galacturonic acid and neutral sugar residues. The carboxyl (and hydroxyl) functional groups present in these residues and in their alkaline degradation byproducts, which are deprotonated at the high pH (12.4) produced during lime slaking, strongly interact with newly formed Ca(OH) crystals acting in two ways: (a) as nucleation inhibitors, promoting the formation of nanosized crystals, and (b) as habit modifiers, favoring the development of planar habit following their adsorption onto positively charged (0001) faces. Adsorption of polysaccharides on Ca(OH) crystals prevents the development of large particles, resulting in a very reactive, nanosized portlandite slurry. It also promotes steric stabilization, which limits aggregation, thus enhancing the colloidal nature of the lime putty. Overall, these effects are very favorable for the preparation of highly plastic lime mortars with enhanced properties.

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Section: Resultsmentioning

confidence: 94%

Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

et al. 2017

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“…35,36 Giles et al 37 found that the dissolution of Ca(OH) 2 at low stirring rate is controlled by the diffusion of calcium and hydroxide ions away from the surface, while the dissolution is surface controlled at an intensive stirring. Since it is generally accepted that polysaccharides adsorb on mineral surfaces through hydrogen bonds or chemical complexation process in which C-2, C-3 and C-6 hydroxyl groups play crucial roles, [38][39][40] the inhibition of Ca(OH) 2 dissolution is likely to occur. In other words, the presence of dextrane may cause progressive Ca(OH) 2 accumulation in the systems containing higher concentrations of dextrans.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Kontrec¹,

Ukrainczyk²,

Babić-Ivančić³

et al. 2011

Croat. Chem. Acta

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Abstract. Precipitated calcium carbonate (PCC) was prepared by means of semicontinuous carbonation of Ca(OH) 2 suspension, at 35 and 45 °C and in the presence of non-ionic dextran and dextran sulfate. The carbonation process was regulated at different predetermined values of electrical conductivity, that corresponded to different concentrations of dissolved Ca(OH) 2 : 0.5 mS cm. The results of physicalchemical characterization of the product showed that calcite was the only polymorphic modification obtained in the whole range of experimental conditions investigated. In addition, it was found that morphology, crystal size distribution and specific surface area of PCC strongly depended on the electrical conductivity / concentration of dissolved Ca(OH) 2 , at which the process was performed: predominantly scalenohedral crystals of higher surface area (about 5 m 2 g −1) were produced at higher electrical conductivity, while at lower electrical conductivity predominantly rhomohedral calcite crystals of relatively low specific surface area were obtained. In the system of the highest electrical conductivity, κ 25 = 5.0 mS cm, and at 35 °C, the addition of non-ionic dextran significantly influenced the process by preventing the regulation. The crystals that appeared were in the form of irregular aggregates of high specific surface area, S ≈ 29 m 2 g −1. FT-IR and TG analyses indicated that the non-ionic dextran was adsorbed onto the calcite surface, most probably by relatively strong and specific interactions between oxygen from the hydroxyl groups of dextran molecules and calcium ions from the crystal surface. On the contrary, the anionic dextran (dextran sulfate) exerted minor effects in the course of semicontinuous carbonation process and in the properties of the final product, PCC. However, the analysis of the precipitate indicated that dextran sulfate was adsorbed at the surfaces, most probably by the weak and non-specific electrostatic interactions. (doi: 10.5562/cca1746)

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“…The interaction mechanism postulated by Liu and Laskowski [52,53], involving formation of a metal hydroxide-dextrin complex, may be applicable in the present system. Such a mechanism has also been hypothesized after FTIR and UV-vis spectroscopic studies of solutions of dextrin in presence of metal hydroxides [54], as well as dextrin adsorption on pyrite in presence of metal ions [50,55]. It is also possible that the two polymers interact with the surface through the hydrophobic interaction, given the significant hydrophobicity of the solution oxidized surface and the high amount of sulfur at the mineral surface (see Table 1) [21].…”

Section: Discussionmentioning

confidence: 92%

The role of mineral surface chemistry in modified dextrin adsorption

Beaussart¹,

Mierczyńska-Vasilev²,

Harmer³

et al. 2011

Journal of Colloid and Interface Science

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Complexation Mechanism of Dextrin with Metal Hydroxides

Cited by 33 publications

References 14 publications

Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

The role of mineral surface chemistry in modified dextrin adsorption

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Complexation Mechanism of Dextrin with Metal Hydroxides

Cited by 33 publications

References 14 publications

Crystallization and Colloidal Stabilization of Ca(OH)2 in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

Crystallization and Colloidal Stabilization of Ca(OH)2 in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

The role of mineral surface chemistry in modified dextrin adsorption

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Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation

Crystallization and Colloidal Stabilization of Ca(OH)₂ in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation