Research

20 pages, 3898 KiB

Open AccessArticle

Calcium Carbonate Polymorphs Growing in the Presence of Sericin: A New Composite Mimicking the Hierarchic Structure of Nacre

by Linda Pastero and Dino Aquilano

Crystals 2018, 8(7), 263; https://doi.org/10.3390/cryst8070263 - 26 Jun 2018

Cited by 9 | Viewed by 5087

Abstract

Bioinspired self-assembled composite materials are appealing both for their industrial applications and importance in natural sciences, and represent a stimulating topic in the area of materials science, biology, and medicine. The function of the organic matrix has been studied from the biological, chemical, [...] Read more.

Bioinspired self-assembled composite materials are appealing both for their industrial applications and importance in natural sciences, and represent a stimulating topic in the area of materials science, biology, and medicine. The function of the organic matrix has been studied from the biological, chemical, crystallographic, and engineering point of view. Little attention has been paid to the effect of one of the two main components of the organic matrix, the sericin fraction, on the growth morphology of calcium carbonate polymorphs. In the present work, we address this issue experimentally, emphasizing the morphological effects of sericin on calcite and aragonite crystals, and on the formation of a sericin-aragonite-calcite self-assembled composite with a hierarchic structure comparable to that of natural nacre. Full article

(This article belongs to the Special Issue Carbonates)

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8 pages, 2040 KiB

Open AccessArticle

Experimental Value of the Specific Surface Energy of the Cleavage {10.4} Calcite Rhombohedron in the Presence of Its Saturated Aqueous Solution

by Emanuele Costa and Dino Aquilano

Crystals 2018, 8(6), 238; https://doi.org/10.3390/cryst8060238 - 30 May 2018

Cited by 10 | Viewed by 3941

Abstract

In this study, we describe a method to obtain experimental values of the surface energy of calcite. A zenithal imaging device was used to acquire pictures of droplets of CaCO₃ saturated aqueous solution on the surface of a calcite crystal sample. Pictures [...] Read more.

In this study, we describe a method to obtain experimental values of the surface energy of calcite. A zenithal imaging device was used to acquire pictures of droplets of CaCO₃ saturated aqueous solution on the surface of a calcite crystal sample. Pictures were used to measure the contact angle between the droplets and the {10.4} calcite surfaces. The method is discussed along with its geometrical ground, as well as the theoretical foundation of the contact angle calculation. A comparison is made with the literature data; a good agreement is found between our experimental values and those obtained from the more recent ab initio calculations. Full article

(This article belongs to the Special Issue Carbonates)

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15 pages, 5949 KiB

Open AccessArticle

Comparative Study on the Sand Bioconsolidation through Calcium Carbonate Precipitation by Sporosarcina pasteurii and Bacillus subtilis

by Chun-Mei Hsu, Yi-Hsun Huang, Vanita Roshan Nimje, Wen-Chien Lee, How-Ji Chen, Yi-Hao Kuo, Chung-Ho Huang, Chien-Cheng Chen and Chien-Yen Chen

Crystals 2018, 8(5), 189; https://doi.org/10.3390/cryst8050189 - 27 Apr 2018

Cited by 13 | Viewed by 6115

Abstract

To investigate potential implications of microbial activity on sand bioconsolidation and subsurface environments, two ureolytic strains, Sporosarcina pasteurii and Bacillus subtilis were tested for the production of calcium carbonate (CaCO₃). Laboratory experiments with monoculture S. pasteurii (column 1) and coculture S. [...] Read more.

To investigate potential implications of microbial activity on sand bioconsolidation and subsurface environments, two ureolytic strains, Sporosarcina pasteurii and Bacillus subtilis were tested for the production of calcium carbonate (CaCO₃). Laboratory experiments with monoculture S. pasteurii (column 1) and coculture S. pasteurii-B. subtilis (column 2) were conducted to determine urea and calcium chloride reactivity and volumetric carbonate formation. Both columns were able to consolidate sand, whereas, column 1 induced greater CaCO₃ precipitation. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed two columns with different mineralogy with calcite, and vaterite formation. Column 1 showed rhombohedral and trigonal crystals morphology, whereas column 2 developed the prismatic calcite and the spherulite vaterite crystals might be due to the differences of the micro-environment caused by the urease expression of these bacterial species. These results indicate the possibility of using those crystals to cement loose sand whereas, highlighted the importance of combining these techniques to understand the geomicrobiology found in the subsurface environments. Full article

(This article belongs to the Special Issue Carbonates)

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22 pages, 23282 KiB

Open AccessArticle

The Carbonate Platform Model and Reservoirs’ Origins of the Callovian-Oxfordian Stage in the Amu Darya Basin, Turkmenistan

by Wenli Xu, Huaguo Wen, Rongcai Zheng, Fengjie Li, Fei Huo, Mingcai Hou and Gang Zhou

Crystals 2018, 8(2), 84; https://doi.org/10.3390/cryst8020084 - 04 Feb 2018

Cited by 5 | Viewed by 6314

Abstract

The Calloviane-Oxfordian carbonates in the northeastern Amu Darya Basin of southeastern Turkmenistan are composed of medium- to thick-bedded, mostly grainy limestones with various skeletal (bivalves, brachiopods, echinoderms, foraminifera, corals, and sponge) and non-skeletal grains (intraclasts, ooids and peloids). Two facies zones, six standard [...] Read more.

The Calloviane-Oxfordian carbonates in the northeastern Amu Darya Basin of southeastern Turkmenistan are composed of medium- to thick-bedded, mostly grainy limestones with various skeletal (bivalves, brachiopods, echinoderms, foraminifera, corals, and sponge) and non-skeletal grains (intraclasts, ooids and peloids). Two facies zones, six standard facies belts and some microfacies types were recognized, and sedimentary model “carbonate ramp-rimmed platform” was proposed and established that can be compared with the classical carbonate sedimentary models. In this model, favorable reservoirs not only developed in the intraplatform shoal of open platform, or reef and shoal on the platform margin, but also in the patch reefs, shoal and mound facies on the upper slope. The reservoir’s pore space is dominated by intergranular and intragranular pores and fissure-pore reservoirs exist with medium porosity and medium to low permeability. Sedimentary facies and diagenetic dissolution are the key controlling factors for the development of high-quality reservoirs. Full article

(This article belongs to the Special Issue Carbonates)

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16 pages, 4485 KiB

Open AccessArticle

Electrocrystallization of CaCO₃ Crystals Obtained through Phosphorylated Chitin

by Nicole Butto, Gustavo Cabrera-Barjas and Andrónico Neira-Carrillo

Crystals 2018, 8(2), 82; https://doi.org/10.3390/cryst8020082 - 03 Feb 2018

Cited by 14 | Viewed by 5724

Abstract

A phosphorylated chitin (Chi-P) derivative was synthesized and its chemical structure was verified with Fourier-transform infrared spectroscopy (FTIR), elemental analysis, and thermogravimetric techniques (TGA). The influence of Chi-P used as a solid template through in vitro electrocrystallization (EC) supported on an indium zinc [...] Read more.

A phosphorylated chitin (Chi-P) derivative was synthesized and its chemical structure was verified with Fourier-transform infrared spectroscopy (FTIR), elemental analysis, and thermogravimetric techniques (TGA). The influence of Chi-P used as a solid template through in vitro electrocrystallization (EC) supported on an indium zinc oxide (ITO) surface on the growth of calcium carbonate (CaCO₃) was studied. CaCO₃ crystals through EC essays were also compared with crystals obtained with the gas diffusion (GD) method. Scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), chronopotentiometry, Raman, and powder X-ray diffractometry (XRD) characterized all resultant inorganic particles. Our findings revealed that the EC method selectively controlled the coexistence of truncate calcite and the metastable phase of vaterite. The crystals’ morphology reflects the electrostatic interaction of phosphate moieties from Chi-P onto CaCO₃ crystals through both EC and GD crystallization methods. We believe that the EC method represents a viable electrochemical approach for studying different inorganic minerals and could be useful as an in vitro classical crystallization method for the design of advanced inorganic materials with desirable shapes and properties. Full article

(This article belongs to the Special Issue Carbonates)

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15 pages, 9446 KiB

Open AccessArticle

Effect of Alginate from Chilean Lessonia nigrescens and MWCNTs on CaCO₃ Crystallization by Classical and Non-Classical Methods

by Marianela Sánchez, Patricio Vásquez-Quitral, Nicole Butto, Felipe Díaz-Soler, Mehrdad Yazdani-Pedram, Juan Francisco Silva and Andrónico Neira-Carrillo

Crystals 2018, 8(2), 69; https://doi.org/10.3390/cryst8020069 - 31 Jan 2018

Cited by 7 | Viewed by 3834

Abstract

In our crystallization experiments, the influence of alginate from Chilean Lessonia nigrescens and functionalized multi-walled carbon nanotubes (MWCNTs) was tested through electrocrystallization (EC) and gas diffusion (GD) methods on the crystal growth of calcium carbonate (CaCO₃) and their possible stabilization of [...] Read more.

In our crystallization experiments, the influence of alginate from Chilean Lessonia nigrescens and functionalized multi-walled carbon nanotubes (MWCNTs) was tested through electrocrystallization (EC) and gas diffusion (GD) methods on the crystal growth of calcium carbonate (CaCO₃) and their possible stabilization of proto-structures in amorphous CaCO₃ (ACC) state through pre-nucleation clusters (PNC) essays with automatic potentiometric titrations were performed. CaCO₃ crystals obtained in the in vitro above-mentioned crystallization systems were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and powder X-ray diffractometer (XRD). Our experimental findings showed that ALG and functionalized MWCNTs stabilized truncated and agglomerated vaterite-like particles through GD and EC methods. While, on the other hand, we obtained qualitative information about induction or inhibition of CaCO₃ nucleation that was provided by potentiometric titrations. Full article

(This article belongs to the Special Issue Carbonates)

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13 pages, 3105 KiB

Open AccessArticle

CO₂ Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber

by Pao Chi Chen and Shun Chao Yu

Crystals 2018, 8(1), 39; https://doi.org/10.3390/cryst8010039 - 16 Jan 2018

Cited by 12 | Viewed by 8360

Abstract

A lab-scale bubble-column scrubber is used to capture CO₂ gas and produce ammonia bicarbonate (ABC) using aqueous ammonia as an absorbent under a constant pH and temperature. The CO₂ concentration is adjusted by mixing N₂ and CO₂ in the [...] Read more.

A lab-scale bubble-column scrubber is used to capture CO₂ gas and produce ammonia bicarbonate (ABC) using aqueous ammonia as an absorbent under a constant pH and temperature. The CO₂ concentration is adjusted by mixing N₂ and CO₂ in the range of 15–60 vol % at 55 °C. The process variables are the pH of the solution, temperature, gas-flow rate and the concentration of gas. The effects of the process variables on the removal efficiency (E), absorption rate (R_A) and overall mass-transfer coefficient (K_Ga) were explored. A multiple-tube mass balance model was used to determine R_A and K_Ga, in which R_A and K_Ga were in the range of 2.14 × 10⁻⁴–1.09 × 10⁻³ mol/(s·L) and 0.0136–0.5669 1/s, respectively. Results found that, R_A showed an obvious increase with the increase in pH, inlet gas concentration and gas temperature, while K_Ga decreased with an increase in inlet gas concentration. Using linear regression, an empirical expression for K_Ga/E was obtained. On the other hand, ammonia bicarbonate crystals could be produced at a pH of 9.5 when the gas concentration was higher than 30% and γ (=F_g/F_A, the gas-liquid molar flow rate ratio) ≥ 1.5. Full article

(This article belongs to the Special Issue Carbonates)

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4789 KiB

Open AccessArticle

Hydrophobic Calcium Carbonate for Cement Surface

by Shashi B. Atla, Yi-Hsun Huang, James Yang, How-Ji Chen, Yi-Hao Kuo, Chun-Mei Hsu, Wen-Chien Lee, Chien-Cheng Chen, Duen-Wei Hsu and Chien-Yen Chen

Crystals 2017, 7(12), 371; https://doi.org/10.3390/cryst7120371 - 11 Dec 2017

Cited by 19 | Viewed by 7278

Abstract

This report describes a novel way to generate a highly effective hydrophobic cement surface via a carbonation route using sodium stearate. Carbonation reaction was carried out at different temperatures to investigate the hydrophobicity and morphology of the calcium carbonate formed with this process. [...] Read more.

This report describes a novel way to generate a highly effective hydrophobic cement surface via a carbonation route using sodium stearate. Carbonation reaction was carried out at different temperatures to investigate the hydrophobicity and morphology of the calcium carbonate formed with this process. With increasing temperatures, the particles changed from irregular shapes to more uniform rod-like structures and then aggregated to form a plate-like formation. The contact angle against water was found to increase with increasing temperature; after 90 °C there was no further increase. The maximum contact angle of 129° was obtained at the temperature of 60 °C. It was also found that carbonation increased the micro hardness of the cement material. The micro hardness was found to be dependent on the morphology of the CaCO₃ particles. The rod like structures which caused increased mineral filler produced a material with enhanced strength. The ¹³C cross polarization magic-angle spinning NMR spectra gave plausible explanation of the interaction of organic-inorganic moieties. Full article

(This article belongs to the Special Issue Carbonates)

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18918 KiB

Open AccessArticle

Crystallization of Calcium Carbonate in Alginate and Xanthan Hydrogels

by Cleo Kosanović, Simona Fermani, Giuseppe Falini and Damir Kralj

Crystals 2017, 7(12), 355; https://doi.org/10.3390/cryst7120355 - 30 Nov 2017

Cited by 23 | Viewed by 10403

Abstract

Calcium carbonate polymorphs were crystallized in alginate and xanthan hydrogels in which a degree of entanglement was altered by the polysaccharide concentration. Both hydrogels contain functional groups (COOH and OH) attached at diverse proportions on saccharide units. In all systems, the precipitation process [...] Read more.

Calcium carbonate polymorphs were crystallized in alginate and xanthan hydrogels in which a degree of entanglement was altered by the polysaccharide concentration. Both hydrogels contain functional groups (COOH and OH) attached at diverse proportions on saccharide units. In all systems, the precipitation process was initiated simultaneously with gelation, by the fast mixing of the calcium and carbonate solutions, which contain the polysaccharide molecules at respective concentrations. The initial supersaturation was adjusted to be relatively high in order to ensure the conditions suitable for nucleation of all CaCO₃ polymorphs and amorphous phase(s). In the model systems (no polysaccharide), a mixture of calcite, vaterite and amorphous calcium carbonate initially precipitated, but after short time only calcite remained. In the presence of xanthan hydrogels, precipitation of either, calcite single crystals, porous polyhedral aggregates, or calcite/vaterite mixtures were observed after five days of ageing, because of different degrees of gel entanglement. At the highest xanthan concentrations applied, the vaterite content was significantly higher. In the alginate hydrogels, calcite microcrystalline aggregates, rosette-like and/or stuck-like monocrystals and vaterite/calcite mixtures precipitated as well. Time resolved crystallization experiments performed in alginate hydrogels indicated the initial formation of a mixture of calcite, vaterite and amorphous calcium carbonate, which transformed to calcite after 24 h of ageing. Full article

(This article belongs to the Special Issue Carbonates)

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