Roles of Additives on Crystal Growth Rate of Precipitated Calcium Carbonate

2007 ◽  
Vol 124-126 ◽  
pp. 707-710 ◽  
Author(s):  
Ji Whan Ahn ◽  
Woon Kyoung Park ◽  
Kwang Suk You ◽  
Hee Chan Cho ◽  
Sang Jin Ko ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Calcium Carbonate ◽  
Flow Rate ◽  
Nucleation Rate ◽  
Gas Flow ◽  
Crystal Growth Rate ◽  
Gas Flow Rate ◽  
Precipitated Calcium Carbonate ◽  
Co2 Gas

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

2007 ◽  
Vol 544-545 ◽  
pp. 693-696
Author(s):  
Woon Kyoung Park ◽  
Ji Whan Ahn ◽  
Sang Jin Ko ◽  
Choon Han
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Aspect Ratio ◽  
Reaction Temperature ◽  
Flow Rate ◽  
Gas Flow ◽  
Precipitated Calcium Carbonate ◽  
Co2 Gas ◽  
Carbonation Process ◽  
Co2 Flow

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.

Roles of Additives on Crystal Growth Rate of Precipitated Calcium Carbonate

2007 ◽  
pp. 707-710
Author(s):  
Ji Whan Ahn ◽  
Woon Kyoung Park ◽  
Kwang Suk You ◽  
Hee Chan Cho ◽  
Sang Jin Ko ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Calcium Carbonate ◽  
Crystal Growth Rate ◽  
Precipitated Calcium Carbonate

Inhibition Mechanism of Magnesium Ion on Carbonation Reaction with Ca(OH)2 and CO2

2006 ◽  
Vol 510-511 ◽  
pp. 990-993 ◽  
Author(s):  
Jeong Hwan Kim ◽  
Ji Whan Ahn ◽  
Sang Jin Ko ◽  
Woon Kyoung Park ◽  
Choon Han
Keyword(s):  
Particle Size ◽  
Aspect Ratio ◽  
Flow Rate ◽  
Gas Flow ◽  
Inhibition Mechanism ◽  
Gas Flow Rate ◽  
High Concentration ◽  
Precipitated Calcium Carbonate ◽  
Carbonation Reaction ◽  
Co2 Gas

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.

scholarly journals Bubble column application on purification of biogas and production of nano-calcium carbonate in continuous process

2020 ◽  
Vol 16 (3) ◽  
pp. 286-291
Author(s):  
Yukh Ihsana ◽  
Putu Adhi Rama ◽  
Sugeng Winardi ◽  
Tantular Nurtono
Keyword(s):  
Calcium Carbonate ◽  
Flow Rate ◽  
Gas Flow ◽  
Bubble Column ◽  
Continuous Process ◽  
Calorific Value ◽  
Co2 Concentration ◽  
Absorption Process ◽  
Gas Flow Rate ◽  
Precipitated Calcium Carbonate

Purification of biogas by removing carbon dioxide content has been developed to increase its calorific value. The CO2  contained in biogas was absorbed by contacting Ca(OH)2 solution and CO2 in the bubble column to produce high purity of biogas and generated precipitated calcium carbonate (PCC) simultaneously. Two sources of CO2 were used in this work, which were CO2 contained in biogas and pure CO2. Pure CO2 was used as a benchmark in this study to show the effect of the presence of methane contained in biogas on the absorption process. The investigation was done in a continuous process. The results showed that the highest absorption of CO2 was obtained in biogas at 79.34 %. PCC with calcite phases was successfully formed in 225–270 nm. Rhombohedral calcite phase was formed by the use of pure CO2 and biogas as a source of CO2. The use of CO2 contained in biogas and pure CO2 in the absorption process did not have an effect on the crystalline phase and morphology of calcite formed. Several factors that significantly affected the absorption of CO2 were gas flow rate, absorbent flow rate, CO2 concentration in the gas inlet, and the initial liquid level in the bubble column. 

scholarly journals TOTAL VOLUMETRIC MASS TRANSFER COEFFICIENT AT CO2 GAS ABSORPTION USING K2CO3 BY MSG PROMOTER

Konversi ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Erlinda Ningsih ◽  
Abas Sato ◽  
Mochammad Alfan Nafiuddin ◽  
Wisnu Setyo Putranto
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Total Mass ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Co2 Gas

Abstract- One of the most widely used processes for CO2 gas removal is Absorption. Carbon dioxide is the result of the fuel combustion process which of the hazardous gases. The aim of this research is to determine the total mass transfer coefficient and analyze the effect of the absorbent flow rate of the absorbent solution with the promoter and the gas flow rate to the total mass transfer coefficient value. The variables consisted of liquid flow rate: 1, 2, 3, 4, 5 liter/min, gas flow rate: 15, 25, 30, 40, 50 liter/min and MSG concentration: 0%, 1%, 3% and 5% by weight. The solution of Pottasium Carbonate as absorbent with MSG promoter is flowed through top column and CO2 gas flowed from bottom packed column. Liquids were analyzed by titration and the gas output was analyzed by GC. From this research, it is found that the flow rate of gas and the liquid flow rate is directly proportional to the value of KGa. The liquid flow rate variable 5 liters / minute, gas flow rate 15 l / min obtained value of KGa 11,1102 at concentration of MSG 5%. Keywords:  Absorption, CO2,  K2CO3, MSG. 

Optimizing diamond growth for an atmospheric oxyacetylene torch

1997 ◽  
Vol 12 (5) ◽  
pp. 1237-1252 ◽  
Author(s):  
Lua'y A. Zeatoun ◽  
Philip W. Morrison
Keyword(s):  
Growth Rate ◽  
Surface Temperature ◽  
Flow Rate ◽  
Gas Flow ◽  
Substrate Surface ◽  
Diamond Films ◽  
Diamond Growth ◽  
Statistical Experimental Design ◽  
Gas Flow Rate ◽  
Open Flame

Diamond growth conditions for an atmospheric combustion flame have been optimized using statistical experimental design. Films are grown on a molybdenum bolt for 40 min at a distance of 1 mm from the flame cone. The diamond films have been characterized using Raman spectroscopy, x-ray diffraction, and scanning electron microscope. The input process variables are varied over a range of conditions: total gas flow rate Q = 2–4 standard liter/min, substrate surface temperature Ts = 800–1000 °C, and flow ratio of O2/C2H2 = R = 0.93–0.99. The experimental response outputs are growth rate, full width half maximum (FWHM) of the diamond Raman peak, Raman diamond fraction (β) in the film, ratio of luminescence to diamond peak height (LR), and the relative intensity of the {220}, {311}, {400}, and {331} orientations. The film quality indices FWHM, β, and LR improve by increasing the gas ratio (R), by increasing substrate surface temperature (Ts), and lowering the growth rate by decreasing total gas flow rate. Diamond film shows a small amount texturing in {220} and {400} orientation at low R and Ts. At high R and low Ts crystals are oriented with the {111} direction normal to the substrate surface. Jet and boundary layer theory have been applied to understand the growth rate, the thickness profile, and the morphological instability of the diamond films. Surface Damkühler calculation shows that the deposition process is marginally controlled by mass transfer. Growth rate of an open flame is higher than for an enclosed flame, while the Raman quality measurements of the enclosed flame are more uniform than open flame over the range of the comparison.

Crystallization kinetics for the system CuSO4-ZnSO4-H2O forming solid solutions

1986 ◽  
Vol 51 (11) ◽  
pp. 2473-2480 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Věra Šnoblová ◽  
Miloslav Karel
Keyword(s):  
Solid Solution ◽  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Solid Solutions ◽  
Nucleation Rate ◽  
Diffusion Mechanism ◽  
Crystal Growth Rate ◽  
Component System ◽  
Metastable Zone

The three-component system CuSO4-ZnSO4-H2O forms three types of solid solution. Metastable zone widths measured for selected solution compositions at two cooling rates were used to calculate the kinetic parameters of nucleation. The rate of crystal growth was measured by the fluidized bed method. The results show that the addition of Zn2+ to a solution of CuSO4 increases both the nucleation and crystal growth rates, whereas Cu2+ added to a solution of ZnSO4 retards the nucleation rate and slightly increases the rate of crystal growth. The nucleation rate (the metastable zone width) is substantially more sensitive to the addition of a second component than is the rate of crystal growth. The crystal growth rate is controlled by a diffusion mechanism.

Studies on nucleation and crystal growth kinetics of plutonium(IV) oxalatex

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chuanbo Li ◽  
Bo Wang ◽  
Xiang Li ◽  
Taihong Yan ◽  
Weifang Zheng
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Nucleation Rate ◽  
Crystal Growth Rate ◽  
Acid Solutions ◽  
Dilution Ratio ◽  
Secondary Nucleation ◽  
Supersaturation Ratio ◽  
Crystal Growth Kinetics ◽  
Kinetics Of

Abstract A new method is developed to calculate the dilution ratio N of the two reactant solutions during nucleation rate determination. When the initial apparent supersaturation ratio S N  = f(N) in the dilution tank is controlled between 1.66 and 1.67, the counted nuclei is the most, both nuclei dissolving and secondary nucleation avoided satisfactorily. Based on this methoed, Plutonium(IV) oxalate is precipitated by mixing equal volumes of tetravalent plutonium nitrate and oxalic acid solutions. Experiments are carried out by varying the supersaturation ratio from 8.37 to 22.47 and temperature from 25 to 50 °C. The experimental results show that the nucleation rate of plutonium(IV) oxalate in the supersaturation range cited above can be expressed by the equation R N  = A N exp(−E a /RT)exp[−B/(ln S)2], where A N  = 4.8 × 1023 m−3 s−1 , and E a  = 36.2 kJ mol−1, and B = 20.2. The crystal growth rate of plutonium(IV) oxalate is determined by adding seed crystals into a batch crystallizer. The crystal growth rate can be expressed by equation G(t) = k g exp(−E’ a /RT) (c − c eq) g , where k g  = 7.3 × 10−7 (mol/L)−1.1(m/s), E’ a  = 25.7 kJ mol−1, and g = 1.1.

Effect of Calcium Carbonate on Crystallization Behavior and Morphology of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)

2017 ◽  
Vol 751 ◽  
pp. 242-251 ◽  
Author(s):  
Sitthi Duangphet ◽  
Damian Szegda ◽  
Karnik Tarverdi ◽  
Jim Song
Keyword(s):  
Crystal Structure ◽  
Growth Rate ◽  
Crystal Growth ◽  
Calcium Carbonate ◽  
Growth Process ◽  
Crystal Growth Rate ◽  
Molecular Weight Determination ◽  
High Concentration ◽  
Sem Images ◽  
Significant Difference

The effects of calcium carbonate (CaCO3) concentration on crystallization behaviors and morphology of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were investigated. Composites of PHBV with CaCO3 were prepared with filler loadings of low (5%wt) and high concentration (20%wt) and these were subsequently compared to unloaded PHBV. The morphologies of PHBV composites on the freeze-fractured specimens were examined using scanning electron microscopy (SEM). The SEM images revealed that increasing concentration of CaCO3 resulted in agglomeration. This agglomeration might affect crystal growth rate and mechanism. The crystal growth behavior of melt-crystallized PHBV with different amounts of CaCO3 was studied by polarized optical microscopy (POM), while the crystal structure was examined by X-ray diffraction (XRD). The rate of crystal growth determined from POM at selected crystallization temperatures revealed that the addition of a small amount of CaCO3 accelerated crystal growth rate, whereas excess amount of CaCO3 had the opposite effect. The POM images were also used to illustrate the change of crystal growth process presence of CaCO3. The unloaded PHBV clearly showed nucleation and growth mechanism, while PHBV composites displayed nucleation and then combination of crystals during the growth process. However, CaCO3 did not affect the crystal structureof any PHBV composite as observed by XRD. Molecular weight determination via gel permeation chromatography (GPC) indicated that there was no significant difference among PHBV composites.

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