Study of Carbonizing Processes for Sintered Dolomite

2007 ◽  
Vol 336-338 ◽  
pp. 2552-2555 ◽  
Author(s):  
Jing Hua Xue ◽  
Min Fang Han ◽  
Qing Yun Wang
Keyword(s):  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Magnesium Hydroxide ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Magnesium Carbonate ◽  
Crystal Phase ◽  
Carbonization Process

It is the easy and widely used way to make light calcium carbonate and magnesium carbonate from dolomite by carbonizing process. During this process, the dolomite is calcined at different temperature, from 700°C to 950°C to get the mixture including either calcium carbonate and magnesia or calcia and magnesia. Then the mixture is blended with water in different temperature from room temperature to 80°C. As a result, it is supposed to get calcium hydroxide and magnesium hydroxide, but XRD analysis reveals that it is not accord with the theory. Magnesium hydroxide can not be obtained during this reaction. After the carbonization process, the calcium carbonate and a kind of mixture which is composed with different crystal phase of Mg5(CO3)4(OH)2[H2O]4 have been produced, instead of magnesium carbonate. The magnesia is gotten when the mixture is calcined at 450~750°C.

Precursors Influence on CaCu3Ti4O12 Synthesis

2012 ◽  
Vol 727-728 ◽  
pp. 1313-1316 ◽  
Author(s):  
Maria Virginia Gelfuso ◽  
Gabriel Moreira Lima ◽  
Daniel Thomazini
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Constant ◽  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Room Temperature ◽  
Microstructural Analysis ◽  
Copper Nitrate ◽  
N Powder ◽  
Scanning Electron

In this work CCTO have been synthesized in two different chemical precursors: calcium hydroxide and copper sulfate were used to compose CCTO-S powder while calcium carbonate and copper nitrate were used to form CCTO-N powder. Calcinations conditions were dramatically different in terms of shelf time and temperature. The CCTO phase was fully obtained for 3 hours of calcination in CCTO-N against the 24 hours to form the same phase in CCTO-S powder. Ceramic bodies densities values for CCTO-S samples were 95% of theoretical density (5.05 g/cm3) and 98% for CCTO-N. The dielectric constant, at room temperature, was obtained for ceramics processed by two routes. Microstructural analysis was conducted by Scanning Electron Microscopy (SEM) and it was performed to explain the dielectric constant differences between CCTO-S and CCTO-N ceramics.

Synthesis of Calcium Carbonate-Polyethylene Oxide Hybrid Nanofibers Through In-Situ Electrospinning

2008 ◽  
Vol 8 (5) ◽  
pp. 2627-2631 ◽  
Author(s):  
Reza Faridi-Majidi ◽  
Naser Sharifi-Sanjani ◽  
Mohammad Madani
Keyword(s):  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Polyethylene Oxide ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Hybrid Nanofibers ◽  
Carbon Dioxide Atmosphere ◽  
Transmission Electron ◽  
Gaseous Carbon Dioxide

In this work, calcium carbonate nanoparticles-polyethylene oxide nanofibers as organic–inorganic hybrid were prepared via in-situ electrospinning. Thus, electrospinning of polyethylene oxide solution saturated with calcium hydroxide was carried out in gaseous carbon dioxide atmosphere. Transmission electron microscopy (TEM) showed that calcium carbonate (CaCO3) nanoparticles were formed on the produced nanofibers of 200–300 nm in diameter. The existence of the formed CaCO3 was also proved by thermogravimetric analysis (TGA) via loss of gaseous CO2 related to the decomposition of CaCO3 at about 500–840 °C. X-ray diffraction (XRD) analysis of the nanofibers showed that the formed CaCO3 nanoparticles have vaterite morphology. DSC analysis was used to determine melting point and to calculate the crystallinity of the produced hybrid nanofibers. The TEM, TGA, XRD and DSC analyses results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution and polyethylene oxide solution having calcium hydroxide, both in air.

The compatibility of DDT with nicotine and alkaline diluents in agricultural dusts

1950 ◽  
Vol 1 (2) ◽  
pp. 178
Author(s):  
RF Powning
Keyword(s):  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Magnesium Carbonate ◽  
Small Extent ◽  
Larvicidal Effect

An alkaline diluent such as calcium hydroxide is generally used in nicotine aphicidal formulations; however, when DDT is mixed with these dusts for added larvicidal effect, it is decomposed rapidly. Experiments show that this decomposition is directly due to the alkaline nature of the diluent and only to a small extent to the effect of the nicotine. A combined dust consisting of DDT and nicotine in pyrophyllite, calcium carbonate, or magnesium carbonate is sufficiently stable for use against cabbage insects and may be stored safely for at least two months.

Effect of Magnesium Ion on the Precipitation of Hollow Calcium Carbonate by Bubble Templating Method

2006 ◽  
Vol 317-318 ◽  
pp. 65-68 ◽  
Author(s):  
Gunawan Hadiko ◽  
Yong Sheng Han ◽  
Masayoshi Fuji ◽  
Minoru Takahashi
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Flow Rate ◽  
Room Temperature ◽  
Crystal Phase ◽  
Magnesium Ion ◽  
Precipitation Condition ◽  
Templating Method ◽  
Hollow Particles

Hollow calcium carbonate (CaCO3) particles were synthesized by bubbling CO2 in the solution of calcium chloride (CaCl2) with the presence of ammonia at room temperature. In this method, CO2 bubble, besides as reactant, has an important role as a template for forming hollow particles. The precipitation was carried out by controlling the precipitation condition, such as pH, flow rate and additives. Hollow calcium carbonate particles were precipitated with the major crystal phase of vaterite. An interesting finding is that magnesium ion (Mg2+) can suppress the transformation of vaterite to calcite by inhibiting the growth of the calcite.

scholarly journals Pure hydroxyapatite synthesis originating from amorphous calcium carbonate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michika Sawada ◽  
Kandi Sridhar ◽  
Yasuharu Kanda ◽  
Shinya Yamanaka
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Molar Ratio ◽  
Final Phase ◽  
Amorphous Calcium Carbonate ◽  
Phosphate Compound ◽  
Synthesis Strategy ◽  
Phosphorylation Reaction ◽  
Subsequent Calcination

AbstractWe report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71 < Ca/P < 1.88), whereas Ca/P = 1.51 leads to pure β-tricalcium phosphate. The ACP phases are precursors for calcium phosphate compounds and may determine the final crystalline phase.

scholarly journals Green Biosynthesis of Silver Nanoparticles Using Leaf Extract of Carissa carandas L. and Their Antioxidant and Antimicrobial Activity against Human Pathogenic Bacteria

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 299
Author(s):  
Reetika Singh ◽  
Christophe Hano ◽  
Gopal Nath ◽  
Bechan Sharma
Keyword(s):  
Silver Nanoparticles ◽  
Pathogenic Bacteria ◽  
Leaf Extract ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Antibacterial Activities ◽  
Effect Of Temperature ◽  
Human Pathogenic Bacteria ◽  
Carissa Carandas ◽  
Antioxidant And Antimicrobial Activity

Carissa carandas L. is traditionally used as antibacterial medicine and accumulates many antioxidant phytochemicals. Here, we expand this traditional usage with the green biosynthesis of silver nanoparticles (AgNPs) achieved using a Carissa carandas L. leaf extract as a reducing and capping agent. The green synthesis of AgNPs reaction was carried out using 1mM silver nitrate and leaf extract. The effect of temperature on the synthesis of AgNPs was examined using room temperature (25 °C) and 60 °C. The silver nanoparticles were formed in one hour by stirring at room temperature. In this case, a yellowish brown colour was developed. The successful formation of silver nanoparticles was confirmed by UV–Vis, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis. The characteristic peaks of the UV-vis spectrum and XRD confirmed the synthesis of AgNPs. The biosynthesised AgNPs showed potential antioxidant activity through DPPH assay. These AgNPs also exhibited potential antibacterial activity against human pathogenic bacteria. The results were compared with the antioxidant and antibacterial activities of the plant extract, and clearly suggest that the green biosynthesized AgNPs can constitute an effective antioxidant and antibacterial agent.

scholarly journals Rosehip Extract-Functionalized Magnesium Hydroxide Nanoparticles and Its Effect on Osteoblastic and Osteoclastic Cells

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4172
Author(s):  
Laura Costa Pinho ◽  
Thais Francini Garbieri ◽  
Liliana Grenho ◽  
Marta M. Alves ◽  
Pedro Sousa Gomes ◽  
...  
Keyword(s):  
Bone Metabolism ◽  
Magnesium Hydroxide ◽  
Pure Water ◽  
Cell Types ◽  
Xrd Analysis ◽  
Osteoblastic Differentiation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Alp Activity ◽  
Mean Diameter ◽  
Magnesium Hydroxide Nanoparticles

Considering the role of magnesium in bone metabolism and the increasing relevance of plant-mediated green-synthesis, this work compares the bone cytocompatibility of magnesium hydroxide nanoparticles (NPs) produced by using pure water, Mg(OH)2, or a rosehip (RH) aqueous extract, Mg(OH)2RH. The NPs were evaluated for dose- and time-dependent effects on human osteoblastic and osteoclastic response, due to the direct involvement of the two cell types in bone metabolism. Mg(OH)2 NPs presented nanoplatelet-like morphology (mean diameter ~90 nm) and a crystalline structure (XRD analysis); the RH-mediated synthesis yielded smaller rounded particles (mean diameter <10 nm) with decreased crystallinity. On the ATR–FTIR spectra, both NPs presented the characteristic Mg-OH peaks; Mg(OH)2RH exhibited additional vibration bands associated with the presence of phytochemicals. On osteoblastic cells, NPs did not affect cell growth and morphology but significantly increased alkaline phosphatase (ALP) activity; on osteoclastic cells, particles had little effect in protein content, tartrate-resistant acid phosphatase (TRAP) activity, percentage of multinucleated cells, and cell area. However, compared with Mg(OH)2, Mg(OH)2RH increased osteoblastic differentiation by inducing ALP activity and promoting the expression of Runx2, SP7, Col1a1, and ALP, and had a negative effect on the expression of the osteoclastic genes NFATC1, CA2, and CTSK. These observations suggest the potential usefulness of Mg(OH)2RH NPs in bone regeneration.

Controlled preparation of micro–nano hierarchical hollow calcium carbonate microspheres by pressurized-CO2 carbonization and their CaCO3:Eu3+ photoluminescence properties

CrystEngComm ◽  
2021 ◽  
Vol 23 (16) ◽  
pp. 3033-3042
Author(s):  
Liubin Shi ◽  
Mingde Tang ◽  
Yaseen Muhammad ◽  
Yong Tang ◽  
Lulu He ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Hierarchical Structure ◽  
Ethylenediaminetetraacetic Acid ◽  
Disodium Salt ◽  
Hollow Microspheres ◽  
Photoluminescence Properties ◽  
Controlled Preparation

Herein, calcium carbonate hollow microspheres with a micro–nano hierarchical structure were successfully synthesized using disodium salt of ethylenediaminetetraacetic acid (EDTA-2Na) as an additive, by bubbling pressurized carbon dioxide and calcium hydroxide at 120 °C.

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