Aragonite Precipitated Calcium Carbonate Research Articles

Formation Characteristics of Precipitated Calcium Carbonate by Carbonation Process

The characteristics and morphology of precipitated calcium carbonate (PCC) particles produced by carbonation process with various experimental conditions are investigated in this study. The crystal structures of PCC formed by carbonation process are calcite and aragonite. The crystal structure of PCC particles synthesized without adipic acid additive is calcite only, regardless of the reaction temperature. Needle-like shape aragonite phase started to form at reactor temperature of 80°C with the adipic acid additive. Particle size of the single phase calcite PCC synthesized without adipic acid additive is about 1 ~ 3 μm, with homogenous distribution. The aragonite PCC also shows uniform size distribution. The reaction temperature and concentration of adipic acid additive do not show any significant effects on the particle size distribution. Aragonite phase grown to a large aspect ratio of needle-like shape showed relatively improved whiteness. The measured whiteness value of single calcite phase is about 95.95, while that of the mixture of calcite and aragonite is about 99.11.

Calcium extraction and synthesis of precipitated calcium carbonate from Mg-rich dolomite

Abstract A green-reaction assisted synthesis using a natural occurring dolomite is reported for precipitated calcium carbonate production over aloe barbadensis miller extract template under ambient condition. Uniform, hierarchical aragonite precipitated calcium carbonate stacked from nanoparticles was synthesized. The tainted Mg influence on resultant PCC purity was averted via D-glucose extraction of dolomite constituent calcium and subsequent precipitation using CO2. The as-synthesized PCC was characterized using SEM, XRD, PSD, and FTIR spectroscopy. Under ambient conditions using carbonation route and 1 L/min CO2 flowrate, aragonite polymorph with hierarchical flower-like structure was produced. Energy is conserved as heat is not required for phase transformation. Minerals & Environment (RAMM) 2018.

Aragonite precipitated calcium carbonate from magnesium rich carbonate rock for polyethersulfone hollow fibre membrane application

Abstract A reaction-assisted synthesis using a naturally occurring dolomite and aloe vera (Aloe barbadensis Miller) extract as a morphological modifier was employed for aragonite-precipitated calcium carbonate (A-PCC) synthesis. The as-synthesized precipitated calcium carbonate was utilized to produce a polyethersulfone (PES) hollow fiber membrane for application of oil-in-water separation. The D-glucose extraction of Ca before precipitation reaction with CO2 dominated the influence of tainted Mg on the as-synthesized PCC purity. The reaction was carried out via the carbonation route and 1 L/min CO2 flowrate at ambient conditions. The aloe vera extract (5 v/v%) and unleached in situ Mg influenced the phase transformation from calcite and vaterite polymorphs to flower-like structure with radiating ends. The A-PCC synthesized using aloe vera did not require external heating, thereby representing an attractive energy-conserving process for this type of precipitated calcium carbonate. The prepared membranes were characterized using porosity, field-emission scanning electron microscope, hydrophilicity, mechanical properties, and pore size. Their performances for oil-in-water filtration were evaluated. At an optimal amount of 3 wt% aragonite PCC in the hollow fiber membrane, the permeate flux and oil rejection reached 102 kg/m2h and >99%, respectively. Furthermore, the introduction of A-PCCs in the PES matrix improved the antifouling properties of the composite membranes. Therefore, PES/A-PCC composite membranes are desirable in treating wastewater and wastewater containing oil.

A Brief review of Aragonite Precipitated Calcium Carbonate (PCC) Synthesis Methods and Its Applications

This article provides an exclusive overview of the synthesized aragonite precipitated calcium carbonate and its applications in various fields. The last decade has seen a steady increase in the number of publications describing the synthesis, characterization and applications of calcium carbonate morphologies. Mainly, two kinds of processes have been developed for the synthesis of aragonite precipitated calcium carbonate under controlled temperature, concentrations and aging, and the final product is single-phase needle-like aragonite precipitated calcium carbonate formed. This review is mainly focused on the history of developed methods for synthesizing aragonite PCC, crystal growth mechanisms and carbonation kinetics. Carbonation is an economic, simple and ecofriendly process. Aragonite PCC is a new kind of functional filler in the paper and plastic industries, nowadays; aragonite PCC synthesis is the most exciting and important industrial application due to numerous attractive properties. This paper describes the aragonite PCC synthetic approaches and discusses some properties and applications.

Synthesis of aragonite-precipitated calcium carbonate from oyster shell waste via a carbonation process and its applications

Oyster shells are abundantly available in nature without eminent use and are dumped into landfills in vast quantities. Their improper disposal causes environmental problems, resulting in a waste of natural resources. Recycling shell waste could potentially eliminate the environmental problems and, moreover, convert the waste into high-valueadded products, such as synthetic precipitated calcium carbonate (PCC), which can be obtained from oyster waste and which is used to enhance the mechanical properties of various materials. It can also be used as a filler material in the plastic and paper industries. This study presents a simple method for the extraction of aragonite needles from oyster shell waste via a carbonation process. The obtained aragonite-precipitated calcium carbonate (PCC) is characterized by XRD and SEM, which is used to assess the morphology and particle size. Using the proposed process, oyster shell waste powder was calcined at 1,000 °C for 2 h, after which the calcined shell powder was dissolved in water for hydration. The hydrated solution was mixed with an aqueous solution of magnesium chloride at 80 °C and CO2 was then bubbled into the suspension for 3 h to produce needle-shaped aragonite PCC. Finally, aragonite-type precipitated calcium carbonate was synthesized from the oyster shell powder via a simple carbonation process, yielding a product with an average particle size of 30-40 μm.

Pilot-scale experimental work on carbon dioxide sequestration using steelmaking slag

The production of precipitated calcium carbonate (PCC) from steel slag has been proposed as a potential method of simultaneously reducing the CO2 emissions from the steelmaking process and turning its waste stream into a valuable product. On average the production of one ton of steel results in two tons of CO2 emissions and 600kg of slag. Globally, more than 400Mt of steel slag are produced annually. If all the slag were used for the production of PCC, 64Mt CO2 could be utilized and 145Mt of calcium carbonate would be produced. In 2014 the research group Energy Engineering and Environmental Protection at Aalto University in Finland has designed, constructed and tested the world’s first mineral carbonation pilot plant test facility that converts steel slag and CO2 into PCC. In batch mode the pilot plant can handle up to 20kg of solid steel slag and 190L of liquid solvent, and it can produce about 10kg of calcium carbonate. The solvent can be regenerated and reused in the calcium extraction stage, which makes the process economically more feasible. Almost 80% of the calcium in the slag was extracted, while more than 70% of the CO2 was utilized and converted into PCC. In high temperature carbonation tests, ammonia gas was detected from the flue gases. At 60°C more than 2vol.% of NH3 was detected in the flue gas, and at 50°C it was 0.65vol.%, while at 45°C the NH3 concentration in the flue gas was only 0.11vol.%. To avoid ammonia evaporation, aragonite PCC can be produced at 45°C by optimizing the CO2 flow rate.The paper presents the process design as well as the early results achieved from the pilot plant. The paper also presents technical challenges that occurred during the scale-up work and experiments.

Preparation of Needle like Aragonite Precipitated Calcium Carbonate (PCC) from Dolomite by Carbonation Method

In this paper, we have developed a simple, new and economical carbonation method to synthesize a pure form of aragonite needles using dolomite raw materials. The obtained aragonite Precipitated Calcium Carbonate (PCC) was characterized by XRD and SEM, for the measurement of morphology, particle size, and aspect ratio (ratio of length to diameter of the particles). The synthesis of aragonite PCC involves two steps. At first, after calcinated dolomite fine powder was dissolved in water for hydration, the hydrated solution was mixed with aqueous solution of magnesium chloride at 80℃, and then CO₂ was bubbled into the suspension for 3 h to produce aragonite PCC. Finally, aragonite type precipitated calcium carbonate can be synthesized from natural dolomite via a simple carbonation process, yielding product with average particle size of 30-40 ㎛.

Calcium carbonate composite hydrogel films: Particle packing and optical properties

AbstractComposite hydrogel films are prepared by photocrosslinking of partially polymerized poly(2‐hydroxyethyl methacrylate‐co‐methyl methacrylate) prepolymer solution dispersed with aragonite precipitated calcium carbonate (PCC) particles. The effects of PCC aspect ratio (AR, 4.2–6.6) and volume fraction (ϕPCC) are studied with respect to the prepolymer viscosity, the maximum packing fraction (ϕm), and optical properties. ϕm obtained from Kreigher–Dougherty fitting is found to decrease with increasing AR of PCC particles, from ϕm = 0.33 (AR = 4.2) to ϕm = 0.21 (AR = 6.6). Scanning electron microscopy images revealed that the particles are uniformly dispersed and randomly orientated in the polymer network when ϕPCC < ϕm. Optically transparent neat hydrogel films become opaque with increasing particle concentration and AR because of random light scattering from the PCC particles. A whiteness up to 80 is obtained from 100 μm thick composite hydrogel film in the wet state with PCC AR = 6.6 and ϕPCC = 0.19 (near ϕm). POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Influence of pigment blends of different shapes and size distributions on coated paper properties

Paper coating pigment plays an essential role in the achievement of the desired end paper qualities. Different pigment varieties are available for paper coating. Ground calcium carbonate (GCC) is the major one used frequently in coating formulations. Precipitated calcium carbonate (PCC) is gradually gaining importance in paper coating, as it can be prepared in different shapes and sizes. The present study was carried out to determine the influence of PCC pigments with different shapes and sizes on paper properties, and their limitations and advantages when blended with finer grade GCC. PCC pigments of calcite and aragonite crystalline polymorphs having rhombohedral, orthorhombic, and scalenohedral habits were selected for the study. It was observed that the viscosity and water-holding capacity of the coating color was reduced with the introduction of PCC in the coating formulation. The PCC pigments showed greater light scattering, opacity, and smoothness of the coated paper as compared to the GCC pigment. The clustered (rosette) shape of scalenohedral habit calcite PCC results in the greatest light scattering, opacity, and surface strength amongst all PCCs. The aragonite PCC of orthorhombic habit and calcite PCC of rhombohedral habit show an almost similar trend in coated paper properties with the greatest smoothness and paper gloss.

The use of iminodiacetic acid for low-temperature synthesis of aragonite crystal microrods: Correlation between aragonite crystal microrods and stereochemical effects

The particle size, morphology, crystallization, and growth of calcium carbonate have been widely studied in the presence of organics, biomacromolecules, and biopolymers. Calcium carbonate with regular surface-relief structures has been synthesized by templating methods in the absence of dual negatively charged organic additives. Although a number of attempts have been made, the large-scale synthesis of 90 wt.% aragonite microrods by a facile route has hitherto remained difficult to achieve at temperatures below 60 °C. By using iminodiacetic acid as a crystal growth modifier, aragonite precipitated calcium carbonate (PCC) in the form of single-crystal microrods has been successfully synthesized at lower temperatures. It has been shown that the crystallographic and morphological characteristics of aragonite PCC microrods synthesized in the presence of iminodiacetic acid at a lower temperature are the same as those of aragonite obtained at 75 °C without an organic additive. The stereochemical relationship between calcium ions and the arrangement around ions bound to the carboxyl groups of iminodiacetic acid is suggested as a potential factor in the oriented nucleation and selectivity for formation of aragonite PCC microrods. The morphology, size, and crystal structure have been characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD).

A New Process to Produce High-Quality PCC by the Causticizing Process in a Kraft Pulp Mill

A new process has been developed to produce high-quality precipitated calcium carbonate as a paper filler by using the causticizing process in a kraft pulp mill. The causticizing process converts green liquor into white liquor in the kraft pulp mill, producing calcium carbonate as a by-product. If the calcium carbonate (CCC) produced by causticizing could be extracted from the process and used as a papermaking material and if makeup quick-lime for white-liquor generation were supplied, rotary lime-kiln operation could be reduced or eliminated, and the consumption of fuel oil and the resulting discharge of carbon dioxide gas could be reduced. However, conventional CCC includes nonuniform particles with large diameters, which cause severe abrasion of plastic wire on paper machines and poor opacity of paper when it is used as a paper filler. To overcome these disadvantages, the challenge was to find a way to control the morphology of CCC produced from causticizing in the same manner as that of commercial precipitated calcium carbonate (PCC). In conventional causticizing, green liquor is mixed with quicklime to produce CCC and white liquor in two steps: slaking of quicklime with water, and causticizing of the slaked lime with sodium carbonate. When these two reactions were separated and precisely controlled, it was found that CCC was obtained in various forms such as rice-, spindle-, and needle-like particles, some of which demonstrated high opacifying ability and little plastic-wire abrasion when used as paper fillers. In particular, the needle-like aragonite CCC crystal produced in this way demonstrated higher opacity in papermaking than commercial aragonite PCC. Based on these laboratory findings, the reactor was scaled up successfully to a mill-scale plant producing needle-like CCC at the Iwakuni mill of Nippon Paper Industries. This plant has been producing good-quality CCC for paper filler and good-quality white liquor for the last five years.

Effects of magnesium chloride and organic additives on the synthesis of aragonite precipitated calcium carbonate

The synthesis of aragonite precipitated calcium carbonate by treating a suspension of Ca(OH) 2 with CO 2 gas was investigated with regard to the effects of Mg 2+ ions and organic additives on polymorphism and alternative orientations. In the presence of a small amount of Mg 2+, Mg-calcite formed, but as the Mg 2+ ion concentration increased, the amount of Mg-calcite decreased and the amount of aragonite increased. Thus, the formation of Mg-calcite is suppressed and only aragonite is formed in the presence of 60 mol% MgCl 2. As the Mg 2+ ion concentration increased, the aragonite that formed was found to have decreased in terms of its longitude and aspect ratio. Furthermore, the effect of Mg 2+ ions in conjunction with organic additives was also investigated with regard to polymorphs and morphology and the structure-forming properties of the organic additives.

Study on the Relationship between Hydration Activity of Calcium Oxide and Characteristics of Precipitated Calcium Carbonate

ABSTRACT The manufacturing process of precipitated calcium carbonate (PCC) is comprised of three steps. First, calcium oxide is obtained by calcination of limestone. The calcium oxide then turns into calcium hydroxide through a reaction with water (hydration process). Finally, PCC is manufactured by a reaction between the calcium hydroxide and carbonate ions. The hydration process is an exothermic reaction and the hydration activity of calcium oxide is expressed as the heat generated during the hydration process. However, at present there is no standard for the measurement method of the hydration activity of calcium oxide. Therefore, in the present study, we investigated the effect of hydration activity of calcium oxide on the manufacturing process of PCC in order to propose a Korean standard for the measurement of hydration activity of calcium oxide. Based on a comparison of the formation yield of PCC with the hydration activity of calcium oxide measured by various methods, it was verified that the characteristics of PCC are strongly affected by the amount of heat generated for a period of 30 seconds after hydration commences. Therefore, the measurement of hydration activity of calcium oxide for manufacturing PCC should be performed during the initial 30 seconds of hydration. We also confirmed that the formation yield of aragonite PCC increases with increasing hydration activity of calcium oxide. In contrast, calcite PCC decreases.

The Effect of Initial Hydration Temperature on the Characteristics of Calcium Hydroxide and Aragonite Precipitated Calcium Carbonate

Precipitated Calcium Carbonate (PCC) is obtained through three processes; that of calcination, hydration, and carbonation. Thus, changes in each process condition determine the particle size or morphology of the mediums (calcium oxide and calcium hydroxide) as well as the product (PCC). To date, studies concerning precipitated calcium carbonate have mainly focused on the carbonation process, aimed at the manufacturing of PCC. Thus far, few studies on calcination or hydration have been conducted. Calcium hydroxide is regarded as the most important factor during the carbonation process. It is obtained through a hydration process. Therefore, in order to create the valuable PCC studies that center on the hydration process should be carried out. The present study seeks to investigate the effect of the hydration condition, particularly the temperature, on the synthesis characteristics of calcium hydroxide and aragonite PCC. The results show that the particle size of calcium hydroxide changes with variations in the initial hydration temperature. In particular, a higher initial temperature resulted in a larger particle size of the calcium hydroxide used in the synthesis. The particle size and yield of aragonite also increased when calcium hydroxide created at high temperatures was used. However, the water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite.

Roles of Additives on Crystal Growth Rate of Precipitated Calcium Carbonate

The characteristics of nucleation and the crystal growth of aragonite-precipitated calcium carbonate in Ca(OH)2 – MgCl2 – CO2 system by a carbonation process is investigated. MgCl2, in this study, was added in order to increase the formation yield of aragonite precipitated calcium carbonate. Optimum conditions of the concentration of the reactants, the temperature and the amount of additives were studied. The formation yield of calcite gradually decreased, and the formation yield of aragonite increased with the addition of MgCl2. A higher formation yield of above 98% for aragonite is obtained by the adding of the Mg2+ ion in a 0.2M Ca(OH)2 – 0.6M MgCl2 – CO2 system at 80. The nucleation rate increased as the temperature decreased and as the CO2 gas flow rate increased. The particle size and aspect ratio increased at a high temperature, a low flow rate of gas, and a high concentration of Ca(OH)2 slurry. Small-sized aragonite was obtained at a low temperature. The increase in crystal size with the decrease in the CO2 gas flow rate can be explained by the decrease in the nucleation rate, in addition to the increase in the crystal growth rate resulting from the decrease in the dissolution rate to CO3 2- ion.

Crystal Growth of Aragonite Precipitated Calcium Carbonate by Seeded Method

Characteristics of nucleation and crystal growth of aragonite precipitated calcium carbonate in Ca(OH)2 – MgCl2 – CO2 system via a carbonation process is investigated. Aragonite precipitated calcium carbonate with high aspect ratio was synthesized at high reaction temperature and concentration of Ca(OH)2 slurry. The increase in crystal size with decreased in CO2 gas flow rate can be explained by a decrease in the nucleation rate and an increase in the crystal growth rate caused by a decrease in the dissolution rate to CO3 2- ion. In this study, crystal growth of aragonite was investigated by adding aragonite seed. It was found that crystal growth of aragonite precipitated calcium carbonate could be controlled by three-step carbonation process using reactants as the Ca(OH)2. Aragonite with an aspect ratio from 5 to 27 and diameter from 3μm to 24μm was thereby grown at a reaction temperature of 80°C and a CO2 flow rate of 50ml/min. It was also found that MgCl2 aqueous solution can be used again in the carbonation process for the synthesis of aragonite precipitated calcium carbonate.

Inhibition Mechanism of Magnesium Ion on Carbonation Reaction with Ca(OH)<sub>2</sub> and CO<sub>2</sub>

The objective of this study is to synthesize the single phase aragonite precipitated calcium carbonate by the carbonation process in the Ca(OH)2-MgCl2-CO2 system. Many researchers reported the influence of Mg2+ ion on the synthetic properties. The inhibition of calcite nucleation and crystal growth, distortion of calcite lattice, and change of surface electrification were investigated. Variety of particle size and aspect ratio were observed according to changes in the concentration of Ca(OH)2 slurry, temperature, and CO2 gas flow rate. The nucleation rate increased when decreasing the temperature and increasing the CO2 gas flow rate. Particle size and aspect ratio increased at high temperature, low CO2 gas flow rate, and high concentration of Ca(OH)2 slurry, however small-sized aragonite was obtained at low temperature.

Preparation of Single-Phase Aragonite Precipitated Calcium Carbonate Used as an Inorganic Eco-Material

In this study, single phase aragonite PCC was synthesized by the solution process using Ca(OH)2 slurry and Na2CO3 solution as the main reactants. To begin with, the formation behavior of PCC polymorphs following changes in supersaturation was investigated, and the optimum synthetic condition of single-phase aragonite PCC was clarified after the role of NaOH in the reaction system was reviewed. In the results, it was considered that lower supersaturation was necessary to obtain a single phase aragonite; and, since the solubility of Ca(OH)2 was decreased with the addition of NaOH by a common ion effect, it is possible to perform a experiment at a lower Ca2+ concentration. In conclusion, in the case of the reaction of the 2.5M NaOH solution, single phase aragonite was obtained. Furthermore, NaOH solution was produced as a by-product in the solution process by reacting Ca(OH)2 slurry with Na2CO3. Thus, recycling of the NaOH solution was attempted in order to clear the environmental issue. It is difficult to recycle directly since the NaOH solution was diluted during the experiment. The optimum condition was investigated by control of experimental factors such as the concentration of Ca(OH)2, Na2CO3 and NaOH, and the reaction temperature, after which the NaOH solution was recycled without re-treatment. The formation characteristics of aragonite PCC, such as formation yield, particle morphology and aspect ratio, were investigated.

Synthesis of single phase aragonite precipitated calcium carbonate in Ca(OH)2-Na2CO3-NaOH reaction system

The formation behavior of precipitated calcium carbonate polymorphs was investigated in three different supersaturation levels. Because the most easily adjustable and influential variable determining supersaturation is the ion concentration of the major reactants — Ca2+ and CO3 3 2− — the supersaturation can be adjusted by changing the ion concentration of these two ions. At high supersaturation, free energy is necessary for a decrease in nucleation, promoting the formation of a sphere-shaped vaterite, while aragonite and calcite were seen to co-exist at medium supersaturation. At low supersaturation, aragonite was mainly formed by mixing with some calcite. Hence, we considered that lower supersaturation was necessary to obtain a single phase aragonite. Furthermore, we found that the solubility of Ca(OH)2 was decreased with the addition of NaOH by a common ion effect. Thus, it is possible to perform an experiment at a lower Ca2+ concentration. The aragonite was synthesized by adding the Na2CO3 solution to the Ca(OH)2 slurry containing several concentrations of NaOH solution at 75°C and under the addition rate of Na2CO3 at 3 ml/min. The formation yield of calcite decreased when the NaOH concentration was increased. In conclusion, in the case of the reaction of the 2.5 M NaOH solution over 210 minutes, single-phase aragonite with an aspect ratio of 20 was obtained.

Formation Mechanism of Aragonite by Substitute of Mg2+Ions

Acicular type aragonite precipitated calcium carbonate was synthesized by carbonation reaction of Ca(OH)₂ slurry and CO₂ gas. As increasing the initial concentration of Mg 2+ ion, calcite crystal phase substantially decreased while that of aragonite crystal phase increased. According to XRD and EDS analysis, it was found that the addition of MgCl₂ induced the Mg 2+ ion to substitute in Ca 2+ ion site of calcite lattice then the unstabled calcite structure be resolved, consequently the growth of calcite structure is interrupted while the growth of aragonite structure is expedited.