Insoluble Carbonate Research Articles

On-Demand Radial Electrodeposition of Alginate Tubular Structures.

We present an electrodeposition technique for fabricating tubular alginate structures. In this technique, two electrodes (anode and cathode) are suspended in a solution of alginate and insoluble calcium carbonate particles, and the application of an electrical potential produces a localized pH change at the anode surface causing suspended divalent cations to become soluble and cross-link the alginate. We robustly characterize how the fabrication parameters influence the rate of radial deposition on the anode, including deposition time, applied voltage, alginate concentration, type of divalent cation and concentration, and anode diameter. Furthermore, we produce gels with a range of tailorable features, including mechanical properties, dimensions (thick-ness and lumen size), customizable tubular geometries, and radial compositional heterogeneity.

РАЗРАБОТКА МАТЕРИАЛА НА ОСНОВЕ ИЗВЕСТКОВО-КАРБОНАТНО-КАЛЬЦИЕВЫХ КОМПОЗИЦИЙ ДЛЯ АДДИТИВНЫХ ТЕХНОЛОГИЙ

The results of experimental studies to determine the possibility of obtaining carbonized material based on lime-carbonate-calcium compositions using inkjet 3D printing are presented. Some types of materials used as connecting for inorganic binders have been studied. An effective method of hardening the model obtained in the process of 3D printing is determined. The physicomechanical characteristics of prototypes solidified in an environment of high concentration of carbon dioxide are defined. It has been established that artificial carbonization of samples obtained on various types of binders for 90 minutes contributes to the formation of a sufficiently strong structure from insoluble calcium carbonate, a product of carbonation of hydrated lime. In this case, the degree of carbonization depends on the type of binder and its mass fraction in solution. The most effective types of binders are selected and the optimal content of the binders in solution is determined. In result, to ensure the production of materials with sufficient physicomechanical properties, a possibility of obtaining carbonized material by the method of 3D inkjet printing at certain optimal contents of the tested binders is confirmed.

A Production Challenge of Ac-225 from RaCO3 Target Activated by Vertical Beam

Ac-225 (t1/2 = 10 d) is regarded as a promising alpha emitter for the targeted alpha therapy (TAT). Considering biodistribution of conjugated antibodies, as well as logistics in worldwide supply, a physical half-life of 10 days would be tolerable for keeping certain radioactivity in each case. Actinium shows a good compatibility to DOTA that is favorable in radiochemistry to enhance the fusion of diagnosis and therapeutic studies including novel radiopharmaceuticals development. However, the current capability of Ac-225 supply is very limited at around 2 Ci/year that mainly relies on the natural source of Th-229 stocked in a few institutes; therefore, any artificial production ways of Ac-225 would be highly desired. Among possible channels of Ac-225 production, protons on Ra-226 (t1/2 = 1600 y) is the sole option we can employ practically, due to the accessibility of target material under the current regulation in our country/institute and high cross-section of this reaction that can be performed on medical cyclotron platforms. Radium-226 used in this study was originated from 1–4 mCi of ‘legacy needles’, presumably being filled as sulfate or bromide with or without carrier Ba, and we successfully collected soluble Ra in HCl followed by the Ref [1]. Then, enriched 40CaCO3 (as carrier), ammonium solution (to make pH>9) and (NH4)2CO3 (to precipitate) in turn were added into 100–500 μCi of Ra/HCl to obtain practically insoluble radium carbonate. The sediment contained RaCO3 was isolated on a filter made of silicon carbide to make Ra target disk, which can be activated directly at our vertical beam station owing to the heat and chemical resistance of SiC, as well as gravity-supported target holding. Irradiations were performed with 18 MeV protons at 3 μA for 3 h (on target 16.7 MeV). The activated target, allowed to decay for about 3 days, was dissolved in 1 M HCl, and then purified to obtain Ac-225 fraction as the final product. Production yield of Ac-225 was roughly estimated to be about 1/200 of Ra-226 activity by this activation condition (1.6 μCi of Ac-225 at the EOB from 360 μCi of Ra-226, in average). Ac-226 (T1/2 = 29 h) was the primal impurity found in our sample that was about 30% with regards to the activity of Ac-225, corrected to the EOB. Although our study is still in development, we concluded that the Ac-225 production from Ra-226 target is feasible that could give sufficient quantity and quality of Ac-225 also in a scaled-up condition with appropriate energy window, cooling time and chemical separation processes. This work was partially supported by JSPS Grant-in-Aid for Scientific Research (C), Grant Number 17K10384. [1]Matyskin, A.V. et al. J. Radioanal. Nucl. Chem. 310 (2016) 589–595.

CO2 Capture via Crystalline Hydrogen-Bonded Bicarbonate Dimers

Summary Limiting global temperature rises is increasingly dependent on the development of energy-efficient carbon-capture methods. Here, we report a simple CO2-separation cycle using an aqueous bis(iminoguanidine) (BIG) sorbent that reacts with CO2 and crystallizes into an insoluble bicarbonate salt. X-ray diffraction analysis of the bicarbonate crystals revealed “anti-electrostatic” hydrogen-bonded (HCO3−)2 dimers, stabilized by guanidinium cations and water. Mild heating of the crystals releases the CO2 and regenerates the BIG sorbent quantitatively, thereby closing the CO2-separation cycle. Experimental and computational investigations support a CO2-release mechanism consisting of surface-initiated low-barrier proton transfer from guanidinium groups to bicarbonate anions with the formation of carbonic acid dimers, followed by CO2 and H2O release in the rate-limiting step, with a measured activation energy of 102 ± 12 kJ/mol. The minimum energy required for sorbent regeneration is 151.5 kJ/mol CO2, which is 24% lower than the regeneration energy of monoethanolamine, a benchmark industrial sorbent.

Direct air capture of CO-2 - topological analysis of the experimental electron density (QTAIM) of the highly insoluble carbonate salt of a 2,6-pyridine-bis(iminoguanidine), (PyBIGH2)(CO3)(H2O)4.

Chemical bonding and all intermolecular interactions in the highly insoluble carbonate salt of a 2,6-pyridine-bis(iminoguanidine), (PyBIGH2)(CO3)(H2O)4, recently employed in the direct air capture of CO2 via crystallization, have been analyzed within the framework of the quantum theory of atoms in molecules (QTAIM) based on the experimental electron density derived from X-ray diffraction data obtained at 20 K. Accurate hydrogen positions were included based on an analogous neutron diffraction study at 100 K. Topological features of the covalent bonds demonstrate the presence of multiple bonds of various orders within the PyBIGH2 2+ cation. Strong hydrogen bonds define ribbons comprising carbonate anions and water molecules. These ribbons are linked to stacks of essentially planar dications via hydrogen bonds from the guanidinium moieties and an additional one to the pyridine nitro-gen. The linking hydrogen bonds are approximately perpendicular to the anion-water ribbons. The observation of these putative interactions provided motivation to characterize them by topological analysis of the total electron density. Thus, all hydrogen bonds have been characterized by the properties of their (3,-1) bond critical points. Weaker interactions between the PyBIGH2 2+ cations have similarly been characterized. Integrated atomic charges are also reported. A small amount of cocrystallized hydroxide ion (∼2%) was also detected in both the X-ray and neutron data, and included in the multipole model for the electron-density refinement. The small amount of additional H+ required for charge balance was not detected in either the X-ray or the neutron data. The results are discussed in the context of the unusually low aqueous solubility of (PyBIGH2)(CO3)(H2O)4 and its ability to sequester atmospheric CO2.

Synthesis of Magnesium Carbonate via Carbonation under High Pressure in an Autoclave

Magnesium carbonate powders are essential in the manufacture of basic refractories capable of withstanding extremely high temperatures and for special types of cement and powders used in the paper, rubber, and pharmaceutical industries. A novel synthesis route is based on CO2 absorption/sequestration by minerals. This combines the global challenge of climate change with materials development. Carbon dioxide has the fourth highest composition in earth’s atmosphere next to nitrogen, oxygen and argon and plays a big role in global warming due to the greenhouse effect. Because of the significant increase of CO2 emissions, mineral carbonation is a promising process in which carbon oxide reacts with materials with high metal oxide composition to form chemically stable and insoluble metal carbonate. The formed carbonate has long-term stability and does not influence the earth’s atmosphere. Therefore, it is a feasible and safe method to bind carbon dioxide in carbonate compounds such as magnesite. The subject of this work is the carbonation of an olivine (Mg2SiO4) and synthetic magnesia sample (>97 wt% MgO) under high pressure and temperature in an autoclave. Early experiments have studied the influence of some additives such as sodium bicarbonate, oxalic acid and ascorbic acid, solid/liquid ratio, and particle size on the carbonation efficiency. The obtained results for carbonation of olivine have confirmed the formation of magnesium carbonate in the presence of additives and complete carbonation of the MgO sample in the absence of additives.

In-situ microbially induced Ca2+ -alginate polymeric sealant for seepage control in porous materials.

SummaryThis paper presents a novel approach of using in‐situ microbially induced Ca2+‐alginate polymeric sealant for seepage control in porous materials. This process comprises two steps: (i) generation of insoluble calcium carbonate inside the pores of porous materials (such as sand) through a microbially induced carbonate precipitation (MICP) process in‐situ and (ii) injection of sodium alginate for in‐situ gelation via reaction between alginate and Ca2+ ions. The experimental results showed that the hydraulic conductivity/permeability of sand decreased with the increase in alginate concentration. When 5% alginate was used with a CaCO 3 concentration of 0.18 g g−1 sand, the permeability of the alginate‐treated sand reduced from 5.0 × 10−4 to 2.2 × 10−9 m s−1. The scanning electron microscopy images revealed that a film‐type coating was formed around sand particles with spherical round crystals embedded. Furthermore, the in‐situ formed Ca‐alginate polymeric sealant can also be used for the removal of Cu2+ ion and suspended particles from contaminated water by more than 90%. Built on the current research, the envisioned practical application of the proposed method may include clogging fractured rock, reducing seepage and prevent piping through dams, excavation dewatering, and forming barriers for remediating specific contaminants.

Simultaneous immobilization of heavy metals in soil environment by pulp and paper derived nanoporous biochars.

BackgroundBiochars are the new generation of sustainable soil amendments which may be applied both to fertilize and remediate the impacted soils. The aim of current research has been synthesis and characterization of pulp and paper-derived biochars and determination of their mechanisms in simultaneous immobilization of heavy metals (Cu2+, Pb2+, and Zn2+) within contaminated soil. In a novel attempt, three different solid wastes of Mazandaran Wood and Paper Industries (barks and effluent sludge) were utilized to produce biochars.MethodsThe thermogravimetric behavior of the three selected biomasses were initially analyzed and the proper pyrolysis condition has been determined, accordingly. Alterations in surface active groups, before and after the pyrolysis process, have been detected by Fourier transform infrared (FTIR) spectroscopy. Elemental analysis and acid digestion procedure have been employed to measure C, H, N, S, O, and P contents of the biochars. Moreover, porosity and morphological characteristics have been monitored by Brauner-Emmet-Teller (BET) porosimetry and scanning electron microscopy (SEM). Batch adsorption tests have been designed and carried out. Finally, a set of soil sequential extraction experiments was performed over both amended/unamended soils which together with a post-sorption FTIR analysis, explained the possible competitive immobilization mechanism.ResultsPorosimetry study indicated the nanoporosity of the chars and the distribution pattern of adsorbed metals over the char samples. Batch sorption tests suggested remarkable uptake capacity for each char. The results of post sorption tests suggested that Cu is mainly involved in organic bonds of -NH2, -OH and -COOH groups, Pb forms insoluble hydroxide, phosphate or carbonate precipitates, and Zn is mostly engaged in the residual fraction.ConclusionsAccordingly, the bulky wastes are confirmed to have the potential to form sustainable biochar soil amendments.

Direct air capture of CO2 via aqueous-phase absorption and crystalline-phase release using concentrated solar power

Using negative emissions technologies for the net removal of greenhouse gases from the atmosphere could provide a pathway to limit global temperature rises. Direct air capture of carbon dioxide offers the prospect of permanently lowering the atmospheric CO2 concentration, providing that economical and energy-efficient technologies can be developed and deployed on a large scale. Here, we report an approach to direct air capture, at the laboratory scale, using mostly off-the-shelf materials and equipment. First, CO2 absorption is achieved with readily available and environmentally friendly aqueous amino acid solutions (glycine and sarcosine) using a household humidifier. The CO2-loaded solutions are then reacted with a simple guanidine compound, which crystallizes as a very insoluble carbonate salt and regenerates the amino acid sorbent. Finally, effective CO2 release and near-quantitative regeneration of the guanidine compound are achieved by relatively mild heating of the carbonate crystals using concentrated solar power.

Sorted patterned ground in a karst cave, Ledenica pod Hrušico, Slovenia

AbstractPatterned ground is a characteristic periglacial landform in polar and alpine environments but has not been systematically studied in karst caves. Here we characterize the periglacial environment and sorted stripes within the Ledenica pod Hrušico ice cave, western Slovenia. The stripes were mapped, sediment depth and grain size were measured, and cave and outside air temperatures were monitored together with ground temperatures. Eleven sorted stripes of coarse limestone debris had developed on 1 m thick silt‐rich sediment, underlain by limestone bedrock. Silt‐rich cave sediments can accumulate as insoluble carbonate residue or during flood events, whereas coarse debris may result from frost shattering. Cold winter air entered the ice cave, but little air exchange occurred during summer, when the cave air temperature slowly rose to a maximum of 5°C. Winter temperature oscillations propagated efficiently to the snow‐free cave floor. Fourteen freeze‐thaw cycles were observed at the patterned‐ground surface during winter 2015/2016 and may cause the differential frost heaving necessary for sediment sorting. Such periglacial conditions and mixtures of silty and coarse sediments can produce sorted patterns in karst caves.

Determination of the 13C/12C Carbon Isotope Ratio in Carbonates and Bicarbonates by 13C NMR Spectroscopy.

This paper is the first study focused on the innovative application of 13C NMR (nuclear magnetic resonance) spectroscopy to determine the bulk 13C/12C carbon isotope ratio, at natural abundance, in inorganic carbonates and bicarbonates. In the past, 13C NMR spectroscopy (irm-13C NMR) was mainly used to measure isotope ratio monitoring with the potential of conducting 13C position-specific isotope analysis of organic molecules with high precision. The reliability of the newly developed methodology for the determination of stable carbon isotope ratio was evaluated in comparison with the method chosen in the past for these measurements, i.e., isotope ratio mass spectrometry (IRMS), with very encouraging results. We determined the 13C/12C ratio of carbonates and bicarbonates (∼50-100 mg) with a precision on the order of 1‰ in the presence of a relaxation agent, such as Cr(acac)3, and CH313COONa as an internal standard. The method was first applied to soluble inorganic carbonates and bicarbonates and then extended to insoluble carbonates by converting them to Na2CO3, following a simple procedure and without observing isotopic fractionation. Here, we demonstrate that 13C NMR spectroscopy can also be successfully adopted to characterize the 13C/12C isotope ratio in inorganic carbonates and bicarbonates with applications in different fields, such as cultural heritage and geological studies.

Effects of the addition of inertized MSW fly ash on calcium aluminate cement mortars

The large urban development carried out in the cities has promoted the increase of municipal solid wastes (MSW). While the incineration process is considered as the best possible method to manage this waste, however, among all the incineration products, MSW fly ashes produce the greatest environmental problems. The inerting of this hazardous toxic waste, as well as its valorization as a by-product is achieved due to its stabilization in the form of insoluble carbonates. In this way, a new “raw material” is produced and available at low cost, and the toxic and hazardous waste is eliminated by its subsequent encapsulation in mortar matrixes. Consequently, conservation of alternative natural resources is strengthened. In this research, calcium aluminate cement (CAC) mortars have been developed incorporating treated fly ash as filler, assimilating 10% in weight of the aggregate and adding it into the mortar dosage as a new formulation. The amount of 10% was chosen taking into account the positive outcomes in the bibliography. Likewise, samples tested covered different cement proportions, both using aggregates with different diameters (0/2 mm and 0/4 mm), and using different cement/aggregate ratios (1/1 and 1/3) of the stated CAC. After having analyzed the physical/mechanical properties of these mortars, the conclusions drawn are that the tested mortars are technically acceptable, with a much shorter workability period than the reference mortars. They also present better dimensional stability and an increase in bulk density. Mercury intrusion porosimetry displays a porosity decrease. In addition, the contribution of CaCO3 develops calcium monocarboaluminate hydrate (C3A·CaCO3·11H2O) which increase the resulting mixtures-those made with CAC·0/4·1/1-compressive strengths up to 48.62% more than the reference mortars.

Polyelectrolyte-based enzymatic diagnosticum with precipitation detection system for urea assay in solution

A polyelectrolyte-based enzymatic diagnosticum with a precipitation detection system that can be used as a biosensor was created. The detection method was based on the change in polyelectrolyte microcapsule weight with respect to the urea content. The possibility of biosensor reutilization was demonstrated. The appropriate ionic precipitator causing precipitation of insoluble carbonate within the microcapsules and the optimal microcapsule titre were found. In the solution of monovalent anions (chlorides), the activity of encapsulated urease was shown to increase monotonically as the square root of the ionic strength depending on the elevation of the salt content. The activity drastically increased in a narrow concentration interval (0.6–0.8 mM) of divalent anions (sulfates) and reached the level of the native enzyme activity.

Evidence of increased rainfall prior to 3500 years BP as revealed by river borne terrigenous flux: A study from west coast of India

The study has been conducted for insoluble residue and Calcium Carbonate content in a 4.80 m long shallow water (at 22 m water depth) sediment core (at 22 m water depth) off Central West Coast of India to reconstruct palaeo monsoonal precipitation linked with river discharge. The down core profile of carbonate content shows that it is generally less than 28% below ca. 3.00 m whereas, above 3.00 m it is generally more than 28% and this showing an general upward trend. On the contrary, the average insoluble residue is marked by higher value (>72%) below ca. 3.00 m while, above 3.00 m it is low (<72%) and showing a general downward trend. These trends ostensibly suggest an increased rainfall prior to around 3500 year BP which resulted in enhanced river discharge along with insoluble residue and diminution of calcium carbonate, (ascribed due to reduced productivity). Such a distinct response of Calcium Carbonate and insoluble residue at 3.00 m, corresponding to around 3500 years BP is congruous with the already established climatic changes of this core at ca. 3500 years BP linked with salinity changes due to alteration of rainfall pattern.

Enhancement of the Stability of Insoluble Calcium Particles Using a Phospholipid Coating

Calcium is one of the most important elements in the human body. Insoluble calcium particles are often used in calcium-fortified food products, such as calcium-fortified milk, dairy beverages or protein powders. However, their suspension may be unstable often leading to precipitation in such products. In this study, three different kinds of insoluble calcium particles, i.e. hydroxyapatite (HA), tricalcium phosphate (TCP) and calcium carbonate (CaCO3) were coated with amphiphilic phospholipids using a solvent-exchange method. Suspension stability of these insoluble calcium particles was effectively improved with phospholipid coating, especially for HA and TCP, as more phospholipids were coated on the surface of these two calcium particles than CaCO3. Phospholipid coating increased the electrostatic repulsions between particles, preventing the particles from aggregating and precipitating. In addition, the digestibility of phospholipid-coated insoluble calcium particles was tested in simulated gastric juice, and the dissolution time of these insoluble calcium particles was prolonged through phospholipid coating.

Synthesis, Characterization, and Photocatalytic Behavior of Praseodymium Carbonate and Oxide Nanoparticles Obtained by Optimized Precipitation and Thermal Decomposition

Direct precipitation of insoluble praseodymium carbonate salt by reaction of the corresponding cation and anion was utilized in this study. This facile, routine, and effective route was optimized statistically through an orthogonal array design for fabrication of nanoparticles, using a Taguchi method to quantitatively evaluate the effects of the major operation conditions on the particle diameter via analysis of variance. The results indicated that high-purity particles with very small dimension (30 nm) could be produced simply by regulating the cation and anion concentrations and flow rate of introducing the cation into the anion solution. The product was thermally decomposed to yield praseodymium oxide nanoparticles by single-stage reaction. Both products were characterized using various conventional techniques including x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy to monitor the effects of the optimization on their physicochemical properties. Furthermore, the photocatalytic behavior of the nanoparticles was evaluated for treatment of water polluted with methyl orange, revealing high efficiency for degradation of the organic pollutant.

Optimal sequestration of carbon dioxide and phosphorus in soils by gypsum amendment

Gypsum has been applied as a natural fertilizer and soil amendment for centuries in agriculture for providing crop nutrients such as Ca and S, and for improving soil physical properties. Recently, gypsum has been tested for sequestrating CO2 from the air and for capturing soluble phosphates in the soil, through formation of insoluble calcium phosphates and carbonates. However, the environmental factors controlling these sequestration processes have not been systemically studied. Here, we calculate optimal conditions of sequestration using chemical equilibrium modeling. Our results show that CO2 carbonation is effective at pH higher than 8.5 at atmospheric concentration. The removal of P is higher than 80 % for pH higher than 6.4, when Ca and P are at stoichiometric ratio. Also, placement of gypsum in subsoil is more effective for CO2 capture than applying it on soil surface since soil pores often contain higher concentrations of CO2 due to the soil respiration process. Overall, increases in medium pH, gypsum application rate, or CO2 partial pressure can increase the effectiveness of the amendment.

Effect of high pressure carbon dioxide processing on pectin methylesterase activity and other orange juice properties

Inactivation of pectinmethylesterase (PME) and quality parameters of orange juice have been studied after high pressure carbon dioxide (HPCD) treatment. The HPCD treatment conditions covered a wide range of temperature from 2 to 40 °C, far below normal thermal treatment, while operating pressure was varied from 10 to 30 MPa and exposure time from 3 to 60 min. A decrease in PME activity was found, even at the lowest temperature studied in this work, 2 °C. Different inactivation kinetic models were used to correlate the PME residual activity: the two-fraction model, the fractional-conversion model and the Weibull model. The two-fraction model presents the lowest mean relative deviation. Some quality parameters such as colour, pH, ºBrix, turbidity, ascorbic acid, total acidity and particle size distribution (PSD) were also determined right after HPCD treatment and along storage at 4 °C up to 12 days. PSD shows that HPCD treatment results in a volume increase of small particles and a volume decrease of large particles regarding the non-treated orange juice. Calcium content was also determined before and after HPCD treatment to check for insoluble calcium carbonate formation but not significant changes were observed in calcium content after HPCD treatment.

A Study on the Migration Behavior of K, Na, and Cl during Biomass Gasification

The migration behavior of the alkali metals and chlorine were studied during rice straw and corn straw gasification in a fixed bed reactor at various temperatures using thermodynamic equilibrium calculations, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive spectrometry (SEM-EDS). The results showed that K and Na were released mostly in chloride form. The release of potassium, sodium, and chlorine increased upon the increase in temperature from 600 to 1000 °C. The maximum amounts of potassium, sodium, and chlorine that were released from rice straw were 38.9%, 18.7%, and 34.9%, respectively. The maximum amounts of potassium and chlorine that were released from corn straw were 24% and 43.6%, respectively, which occurred at 1000 °C. The maximum amount of sodium released from corn straw was 77.6%, at 700 °C, and the amount of sodium released was greater than that of potassium. Most of the potassium and sodium was converted into insoluble carbonate, sulfate, silicate, and aluminosilicate compounds in the gasification ash.

The Role of Nanoporous Biochars Functional Groups for Immobilization of Heavy Metals&lt;sup&gt; &lt;/sup&gt;in Aqueous Solution

The affinity of nanoporous biochars functional groups for immobilization Cu, Zn, and Pb in aqueous solution has been studied. BET results revealed the nanoporous structure of the chars. Batch experiments have been designed and performed.The results indicated remarkable sorption capacity in case of each char: in a multi-metal system, B1, B2, and B3 adorbed 24.39, 23.61, 35.69 mg/g copper, 63.36, 90.96, 95.36 mg/g lead, and 20.16, 21.26, and 25.44 mg/g zinc, respectively. To find out the sorption mechanism with a post-sorption FTIR analysis over the biochars has been made. The results suggest the possible competitive immobilization mechanism as Cu being mainly organically bounded to amino, hydroxyl and carboxyl functional groups, Pb forming insoluble hydroxide, phosphate or carbonate, and Zn being mostly sorbed in the residual fraction.