Carbonate-based Materials Research Articles

Microfluidic-assisted synthesis of hybrid calcium carbonate/silver microparticles

The development of advanced methods for the synthesis of nano- and microparticles for biomedical applications is of considerable interest. A method for the synthesis of submicron silver-shelled calcium carbonate particles using a microfluidic chip designed to provide control over particle formation is proposed. Precise control of reaction parameters enables the formation of silver shell and calcium carbonate particles in a controlled manner. The distribution of pores in the hybrid particles was analyzed using small-angle X-ray scattering, which provided insight into the complex structure of the pores. The results provide information on particle morphology and may facilitate the development of new calcium carbonate-based materials for various applications.

Short-lived calcium carbonate precursors observed in situ via Bullet-dynamic nuclear polarization

The discovery of (meta)stable pre-nucleation species (PNS) challenges the established nucleation-and-growth paradigm. While stable PNS with long lifetimes are readily accessible experimentally, identifying and characterizing early-stage intermediates with short lifetimes remains challenging. We demonstrate that species with lifetimes ≪ 5 s can be characterized by nuclear magnetic resonance spectroscopy when boosted by ‘Bullet’ dynamic nuclear polarization (Bullet-DNP). We investigate the previously elusive early-stage prenucleation of calcium carbonates in the highly supersaturated concentration regime, characterizing species that form within milliseconds after the encounter of calcium and carbonate ions and show that ionic pre-nucleation species not only govern the solidification of calcium carbonates at weak oversaturation but also initiate rapid precipitation events at high concentrations. Such, we report a transient co-existence of two PNS with distinct molecular sizes and different compositions. This methodological advance may open new possibilities for studying and exploiting carbonate-based material formation in unexplored parts of the phase space.

Construction of high-capacitance carbonate-rich bimetallic layered (hydr)oxides onto ZIF-67–derived Co/CoO-N-carbon hybrid cubes for high-performance symmetric supercapacitors

Herein, we fabricated carbonate-rich bimetallic layered hydr(oxides) (CoMnOx), which are primarily used as active materials for supercapacitors, using a simple hydrothermal method. CoMnOx was deposited onto cobalt oxide (CoO), which was produced by pyrolyzing ZIF-67 at 800 °C under N2 atmosphere. The Co/CoO cubes synthesized using carbonized ZIF-67 (ZIFC) were covered with CoMnOx shells with high reduction efficiency and abundant Co active sites and surface O species. The effects of the carbonate species present between the CoMnOx layers and at the surface of the hybrid CoMnOx@ZIFC materials were evaluated using PXRD and XPS. The peaks at the binding energies of 290 and 400 eV in the C 1s and N 1s XPS profiles of CoMnOx@ZIFC, respectively, indicate the presence of carbonate species and coordination of CoO and Co with the N-rich carbon materials, respectively. The FE-SEM images of CoMnOx@ZIFC revealed the partial decomposition of the cubic structure of ZIFC, which agreed with previously reported data. Moreover, the elemental composition of CoMnOx@ZIFC was confirmed using EDS mapping and point analysis. The CoMnOx@ZIFC electrodes exhibited a remarkable specific capacitance/capacitor of 963 F g−1/588 C g−1 at 1 A g−1 and excellent cycling stability over 1000 cycles, which was superior to those of previously reported MOF-derived carbonate-based materials in alkaline electrolytes. The CoMnOx@ZIFC||CoMnOx@ZIFC symmetric supercapacitor exhibited an energy density of 60.75 W h kg−1 with a power density of 5947 W kg−1 and an exceptional cycling stability (>99.5 %) after 3000 cycles.

New Carbonate-Based Materials and Study of Cytotoxic Capacity in Cancer Cells.

Calcium carbonate, one of the most commonly found biominerals produced by organisms, has shown great potential for the development of systems with biological applications due to its excellent biocompatibility, biodegradability, and simple chemical composition. Here, we focus on the synthesis of various carbonate-based materials with vaterite phase control and their subsequent functionalization for applications in treating glioblastoma, one of the most limiting tumors currently without effective treatments. The incorporation of l-cysteine into the systems increased cell selectivity while the incorporation of manganese supplied the materials with cytotoxic capacity. Extensive characterization of the systems by infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, X-ray fluorescence, and transmission electron microscopy confirmed the incorporation of the different fragments causing selectivity and cytotoxicity to the systems. To verify their therapeutic activity, the vaterite-based materials were tested in the CT2A cell line (murine glioma) and compared to SKBR3 (breast cancer) and HEK-293T (human kidney) cell lines. These studies on the cytotoxicity of the materials have shown promising results that can encourage future in vivo studies in glioblastoma models.

Nutrient-doped synthetic silicates for enhanced weathering, remineralization and fertilization on agricultural lands of global cold regions- A perspective on the research ahead.

There is now a dire demand for negative emissions technologies (which sequester CO2 from the atmosphere) that can be rapidly deployed, are scalable, and are demonstrably safe and effective. Enhanced weathering of silicate minerals has demonstrated a significant potential for CO2 capture and sequestration by the formation of pedogenic carbonates in soils, subsoils, and sediments. This technique has also been shown to deliver fruitful results in terms of improving soil health, and in turn plant health, through remineralization. The silicate minerals that possess the highest weathering rates (e.g., wollastonite), are relatively rare in nature, whereas the abundant ones (e.g., anorthite and forsterite) have a slower pace of weathering, especially in colder and drier climates such as found in the extensive agricultural lands of Western Canada and the Western United States. Herein, we offer a perspective on the opportunities for computational studies targeting atomic-scale interaction of CO2 with silicates and synthesis of fast-weathering silicates (such as larnite and bredigite), whose composition can be tuned to also support soil fertilization and remineralization, and whose production must be integrated with green and carbon-neutral technologies to ensure net-negative life cycle emissions.

Bio-Cementation: An Eco-Friendly Solution to Reduce the Water Infiltrations in Hidrotechnical Concrete Elements

Abstract The bio-cementation repairing technique consists in using a bio product which precipitates in a porous environment and thus, filling the internal voids. In the construction industry, there is a series of applications for this repairing technology, mainly for cementitious materials. In this respect, the calcium carbonate-based materials are considered to be the most suitable bio products since they are compatible with a wide range of concrete mixes. This paper presents a method of manufacturing a calcium carbonate bio product, using a device designed and manufactured exclusively for this experimental work. In order to design a bio product with an unique set of properties, various preliminary samples, obtained by varying the material quantities, the preparation time and working temperatures, have been tested. The bio product analyzed in this work may increase the impermeability of mortar and concrete elements, by continuous sealing of microcracks that can occur throughout the life cycle of the members. Thus, since this bio product was meant to be a component of the mortar/concrete mixture, the mechanical properties were determined by testing several mortar samples made with different cement-bio product ratios.

Overcoming Barriers in Polycarbonate Synthesis: A Streamlined Approach for the Synthesis of Cyclic Carbonate Monomers

Accessing cyclic carbonate monomers on a large scale is critical for the development of any new carbonate-based materials platform. The synthesis of carbonate monomers can be a challenging and tedi...

Eggshell-templated synthesis of PbS/CaCO3 nanocomposites for [rad]CO3− mediated efficient degradation of tetracycline under solar light irradiation

Photocatalytic degradation reactions have been reported to be mediated by hydroxyl radicals, superoxide radical or photogenerated electrons and holes. The significant role of carbonate radicals in the photocatalytic degradation of carbonate-based materials has been largely ignored to date. Herein, we report carbonate radical mediated photocatalytic degradation of tetracycline hydrochloride by using eggshell-based PbS/CaCO3, exhibiting a remarkably enhanced photocatalytic activity. This research represents a fundamental breakthrough toward the green synthesis of semiconductors/CaCO3-based photocatalysts and understanding of significant role of carbonate radical in photocatalytic degradation processes.

Novel synthetic vertebrae provide realistic haptics for pedicle screw placement.

During vertebral surgery, misplaced pedicle screws can harm vital neural and vascular structures. Haptic distinction between cortical and cancellous bone structures is therefore essential for correct screw placement. This tactile experience during pedicle screw placement can be obtained by training on human or animal specimens even if expensive or ethically questionable. In this study, novel synthetic vertebrae were evaluated within a hybrid simulator to provide realistic haptics for the training of spine surgeries. Synthetic vertebrae were custommade of calcium powder-based composites imitating both, cancellous and cortical bone. The mechanical properties of synthetic surrogates were validated for pedicle screw placement and cement augmentation and were compared with those obtained from human vertebrae and insertion torques were analyzed. In human vertebrae pedicle screw torque measurements resulted in mean torque slopes of 82±33Nm/m. Calcium carbonate-based materials achieved lower torques than the human bone whereas calcium phosphate-based bone surrogates showed comparable results. A further differentiation of the calcium phosphate-based vertebrae revealed, that synthetic vertebrae with lower amounts of blowing agent, achieved suitable torques (83 ± 28Nm/m) in comparison to the human reference (p = 0.39). Cement application and subsequent fluoroscopy images confirmed, that the cancellous core of the synthetic vertebrae enabled cement augmentation. In conclusion, our findings suggest, that the artificial bone samples mimic the properties of human bone during pedicle screw placement and cement augmentation and are therefore suitable as synthetic vertebrae in a hybrid surgical simulator.

Novel bone surrogates for cranial surgery training

Parietal graft lifts are trained on human or animal specimens or are directly performed on patients without extensive training. In order to prevent harm to the patient resulting from fast rotating machinery tools, the surgeon needs to apply appropriate forces. Realistic haptics are essential to identify the varying parietal bone layers and to avoid a penetration of the brain. This however, requires experience and training. Therefore, in this study, bone surrogate materials were evaluated with the aim to provide an anatomically correct artificial skull cap with realistic haptic feedback for graft lift training procedures. Polyurethane composites made of calcium carbonate and calcium phosphate were developed and were used to create customized bone surrogates, imitating both cancellous and cortical bone. Mechanical properties of these surrogates were validated for drilling, milling and sawing by comparison with human parietal bones. For that, surgical tool tips were automatically inserted into artificial and human bones in a customized test bench and the maximum axial insertion forces were analyzed. Axial tool insertion measurements in human parietal bones resulted in mean maximum forces of 1.8±0.5N for drilling, 1.7±0.3N for milling and 0.9±0.1N for sawing. Calcium carbonate-based materials achieved higher forces than the human bone for drilling and milling, and lower forces for sawing. The calcium phosphate-based bone surrogates showed comparable axial insertions forces for all investigated tools and were identified as a suitable surrogate for drilling (p=0.87 and 0.41), milling (p=0.92 and 0.63) and sawing (p=0.11 and 0.76) of the cortical layer and the cancellous bone, respectively. In conclusion, our findings suggest, that a suitable material composition for artificial parietal bones has been identified, mimicking the properties of human bone during surgical machinery procedures. Thus, these materials are suitable for surgical training and education in simulator training.

How nature grows one tough biomineral

By weaving tiny bits of protein into the lattices of growing crystals, nature long ago figured out how to convert calcium carbonate, a brittle, fragile material, to the tough biomineralized form of calcite, the carbonate-based material from which seashells and some animal claws are made. Just recently, scientists figured out how nature does it. The new study shows that the mechanism controlling calcite crystallization is directed by surface chemistry, not simple physical processes, as had been commonly assumed. The findings could lead to new strategies for synthesizing tough composites and CO2 storage materials. Materials scientist James J. De Yoreo of Pacific Northwest National Laboratory described his team’s study at the American Chemical Society national meeting in San Diego last week. To probe the biomineralization process, De Yoreo and colleagues exposed a freshly cleaved calcite crystal to a concentrated water-based solution of calcium carbonate in an atomic force microscopy liquid sample

Removal of hydrogen sulfide at ambient conditions on cadmium/GO-based composite adsorbents

Cadmium-based materials with various hydroxide to carbonate ratios and their composites with graphite oxide were synthesized by a fast and simple precipitation procedure and then used as H2S adsorbents at ambient conditions in the dark or upon a visible light exposure. The structural properties and chemical features of the adsorbents were analyzed before and after hydrogen sulfide adsorption. The results showed that the high ratio of hydroxide to carbonate led to an improved H2S adsorption capacity. In moist conditions cadmium hydroxide was the best adsorbent. Moreover, it showed photoactive properties. While the incorporation of a graphene-based phase slightly decreased the extent of the improvement in the H2S adsorption capacity in moist conditions caused by photoactivity, its presence in the composites enhanced the performance in dry conditions. This was linked to photoactivity of CdS that can split H2S resulting in the formation of water in the system. The graphene-based phase enhanced the electron transfer and delayed the recombination of photoinduced charges. Carbonate-based materials showed a very good adsorption capacity in dark conditions in the presence of moisture. Upon the light exposure, CdS likely photocatalyzes the reduction of carbonate ions to formates/formaldehydes. Their deposition on the surface limits the number of sites available to H2S adsorption.

Evaluation of mineral substrates for in situ iron removal from groundwater

Calcium carbonate-based materials (CCBM) have been found to remove Fe(II) and other divalent metal cations from aqueous solution and thus have the potential for incorporation into remediation systems to remove Fe(II) from groundwater at landfills. Research was conducted to examine the ability of a range of CCBM to remove Fe(II) and assess the mechanism of removal. Different CCBM (limestone, concrete, dolomite, marble), as well as gypsum, witherite, and quartz sand, were tested for their ability to remove Fe(II) from water using batch tests conducted under anaerobic conditions. Limestone (specific surface area of approximately 0.46 m2/g) was found to have the best removal effectiveness, and the final Fe(II) concentration was reduced from 50 to <0.01 mg/L. Kinetics experiments conducted over a 72 h period indicated that the removal process of Fe(II) by CCBM was a two-step process. The first step is rapid sorption of Fe(II) onto the CCBM surfaces within the first hour, and the second step is relatively slow co-precipitation of iron-containing solids formed through various chemical reactions. The two best performing CCBM (limestone and concrete) were evaluated for their removal ability based on media particle size (diameters of 3–5, 7–10, 15–25, and 40–50 mm) and revealed statistically significant (p < 0.01) increases in Fe(II) removal for each particle size class examined. SEM analysis of reacted materials revealed visible precipitates on the reactive material surface; XRD analysis was not able to detect crystalline Fe minerals on limestone surface.

Effects of solution chemistry on the removal reaction between calcium carbonate-based materials and Fe(II)

Elevated iron concentrations have been observed in the groundwater underlying and surrounding several Florida landfill sites. An in situ groundwater remediation method for iron (present as soluble ferrous iron) using a permeable reactive barrier composed of calcium carbonate-based materials (CCBMs), such as limestone, was examined as a potentially effective and low-cost treatment technique. The effects of various environmental factors (i.e., pH, co-existing cations, and natural organic matter (NOM)) on the removal reaction were investigated using laboratory batch studies. Solution pH had a minor effect on iron removal, with superior iron removal observed in the highest pH solution (pH of 9). Sodium and calcium tended to impede the iron removal process by increasing the ionic strength of the solution. Manganese competes with iron ions at the adsorption sites on CCBMs; therefore, the presence of manganese prohibits iron removal and reduces removal effectiveness. NOM was found to decrease Fe(II) uptake by CCBMs and reduce the removal effectiveness by complexing Fe(II), most likely through the carboxyl group, thereby maintaining Fe(II) mobility in the aqueous phase.

Using eggshell waste in red wall tiles

Large quantities of eggshell waste are discarded in the food processing industry. This work investigates the incorporation of eggshell waste as a raw material into a wall tile body, replacing natural carbonate material by up to 15 wt%. Formulations containing eggshell were uniaxially dry pressed and fired at 1150°C using a fast-firing cycle. Physico-mechanical properties of the fired tiles (e.g. linear shrinkage, water absorption, apparent density, flexural strength) were then determined. Development of the microstructure was followed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses. The results showed that eggshell waste could be used in wall tiles, in the range 5–10 wt%, as a partial replacement for traditional carbonate-based materials with only a slight decrease in the end product properties.

Improvements in calibration procedures for the quantitative determination of trace elements in carbonate material (mussel shells) by laser ablation ICP-MS.

A better repeatability and accuracy in the quantitative determination of trace elements in mussel shells or carbonate-based materials by LA-ICP-MS was achieved by using a series of multielement calibration standards prepared by co-precipitation of twelve elements into a CaCO3 matrix in order to improve the homogeneity of the resulting powder samples. Pressed powder discs of good mechanical stability could be obtained at a pressure of 50 MPa, without the addition of a binder. An UV laser (modified Nd:YAG, 266 nm) was used in the Q-switched mode at a repetition rate of 10 Hz and an energy level of 3.5 mJ. Correlation coefficients (R) for the linear calibration graphs (concentration range: 1.5-400 microg/g) for Cr, Mn, Co, Cu, Zn, As, Cd, Sn, Ba, and Pb are generally better than 0.997. The detection limits for all elements investigated are in the sub-microg/g range. Incorporation of elements into the matrix by co-precipitation has shown as a superior method for producing calibration standards than the simple mixture of the analytes (in carbonate or oxide form) with the matrix (CaCO3) or addition of standard solutions to a carbonate powder base. Two examples of the quantitative determination of toxic elements in mussel shells will be presented.