Investigation of Ultrasonication and/or Mechanical Stirring on the Reactive Crystallization of Calcium Carbonate at Lower Temperature and Higher Supersaturation Condition

2021 ◽  
pp. 126243
Author(s):  
Ma Ming ◽  
Zhang Bing ◽  
Lu Weipeng ◽  
Wang Yihu ◽  
Cao Xiaofeng ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Mechanical Stirring ◽  
Lower Temperature ◽  
Reactive Crystallization

An Improvement in Sintering Property of β-Tricalcium Phosphate by Addition of Calcium Pyrophosphate and Calcium Carbonate

2005 ◽  
Vol 475-479 ◽  
pp. 2359-2362 ◽  
Author(s):  
Xin Long Wang ◽  
Hong Song Fan ◽  
Xing Dong Zhang
Keyword(s):  
Phase Transition ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Tricalcium Phosphate ◽  
Degradation Rate ◽  
Calcium Pyrophosphate ◽  
Sintering Behavior ◽  
Second Phase ◽  
Lower Temperature

b-tricalcium phosphate(TCP, Ca3(PO4)2) ceramics are preferred as a bioceramics because of its chemical stability and reasonable degradation rate in vivo, but it is difficult to obtain b-TCP ceramics with high compressive strength at lower temperature than that of phase transition to a-TCP. In this study, the sintering behavior of TCP, Ca2P2O7-doped TCP, and CaCO3-doped TCP in the range of 2wt%~5wt% were investigated respectively. Phase transition of pure TCP took place between 1100°C to 1150°C, and pure b-TCP ceramics could achieve a compressive strength of only 3MPa. However, calcium pyrophosphate (CPP, Ca2P2O7) additive prevented the transformation of b-TCP to a-TCP, but the second phase of CPP was observed in the resultant ceramics. Phase transition of TCP ceramics by addition of both CPP and calcium carbonate (CC, CaCO3) took place between 1200°C to 1250°C and the resultant TCP ceramics had few impurity of CPP. By adding CPP and CC to TCP, final ceramics with compressive strength over 12MPa could be obtained when sintered at 1200°C for 2hrs.

Characteristics of Calcium Carbonate Crystal Structure and Size Distribution in Solution under the Electromagnetic Field

2011 ◽  
Vol 284-286 ◽  
pp. 2136-2140
Author(s):  
Xiao Kai Xing ◽  
Rui Yan Sun ◽  
Shi Gang Wang
Keyword(s):  
Crystal Structure ◽  
Electromagnetic Field ◽  
Calcium Carbonate ◽  
Size Distribution ◽  
Particle Growth ◽  
Electromagnetic Treatment ◽  
Particles Size Distribution ◽  
Lower Temperature ◽  
Precipitate Nucleation ◽  
Chemical Water

Various non-chemical water treatment methods have been utilized to solve fouling problems. All of these methods have never been scientifically proven to be a valid tool for controlling scales, and one of reasons could be the lack of understanding of the operational principle and treatment mechanisms. The present study focuses on characteristics of calcium carbonate crystal size distribution in solution and crystal structure on the surface under the electromagnetic field in order to comprehend the mechanisms of the Electromagnetic treatment device (ETD). An electromagnetic treatment setup was built for treating scaling water, and a series of fouling tests were carried out with and without ETD, analyzing the particles size distribution in solution by Dynamics Light Scattering (DLS) technology and making Scanning Electron Microscope (SEM) photos. The main results were as follows：The number of precipitate nucleation in solution was few and the particle growth was slow without ETD. In opposition to the case untreated, a rapid particle growth was observed and the number of nucleation was expected to be more, due to the ETD effectively increasing the ions and crystals collision frequency and effectiveness by utilizing the induced electric field. It was implied that the particle growth was promoted mainly by coagulation process but not nucleation growth in all the experimental temperature range. In the high temperature, the crystal phase of calcium carbonate could be changed from aragonite type without ETD to calcite with ETD. In the lower temperature, all the precipitated crystals in solution were calcite and there were little differences between with ETD and without ETD.

OBTAINING MICROPARTICLES OF CALCIUM CARBONATE LOADED WITH MICROBIAL LIPASE

2020 ◽  
Author(s):  
Valeria K. Scherbakova ◽  
Alla A. Krasnoshtanova
Keyword(s):  
Calcium Carbonate ◽  
Specific Activity ◽  
Low Cost ◽  
Operational Stability ◽  
Alkaline Ph ◽  
Leather Industry ◽  
Operating Stability ◽  
Protein Molecules ◽  
Egg Powder ◽  
Lower Temperature

At present, lipases of animal and microbial origin are increasingly used in human practice, namely in cheese production, milk chocolate production, confectionery industry, dry egg powder, production of flour, leather industry (for degreasing wool, bristles, leather), silk production, washing agents, as well as biodiesel. However, the practical use of lipase is limited by its low stability, reduced storage activity, and inability to reuse. One way to overcome these disadvantages is to microencapsulate the enzyme into various carriers. One promising carrier is calcium carbonate, characterized by ease of production and low cost. Therefore, the purpose of this work was to select the conditions for including lipase in the calcium carbonate microparticles. As the subject of the investigation, lipase of bacteria p. Pseudomonas fluorescens with activity of 27 u/mg was used in the work. This paper compares two methods of including protein molecules in carbonate microparticles: adsorption in pores (previously prepared carrier microparticles are added to the protein solution) and microencapsulation (formation of microparticles occurs simultaneously with inclusion of protein molecules). For both ways the capacity of microparticles of a carbonate of calcium by a bacterial lipase was determined and it was established that the maximum capacity equal was 0.2 mg/mg was reached when using a method of adsorption in pores. The specific activity of lipase in this case is 5.21 units/mg. The dynamics of bacterial lipase release from carbonate microparticles has been investigated. It has been found that within 90 minutes the degree of lipase release from microparticles does not exceed 28%, and the decrease in its specific activity does not exceed 10%. This fact suggests a higher prolongation of the action of lipase included in calcium carbonate microparticles compared to native. The operational stability of the bacterial lipase included in the calcium carbonate microparticles was evaluated as compared to native lipase. It was found that the temperature optimum did not occur, it remained at 37 ° C, but the operating stability increased in the lower temperature area. The optimum pH shifted from the slightly alkaline (pH 8.0) towards the neutral (pH 7.0), wherein in the region of alkaline pH values the operational stability of the microencapsulated lipase significantly increases. Microencapsulation of bacterial lipase into carbonate microparticles has been shown to increase storage stability by a factor of twice that of native.

scholarly journals Reactive crystallization of calcium carbonate by liquid-liquid reaction.

1987 ◽  
Vol 20 (4) ◽  
pp. 374-379 ◽  
Author(s):  
HIDEKI TSUGE ◽  
YASUSHI KOTAKI ◽  
SHIN-ICHI HIBINO
Keyword(s):  
Calcium Carbonate ◽  
Liquid Reaction ◽  
Reactive Crystallization

Polymorph control of calcium carbonate by reactive crystallization using microbubble technique

2010 ◽  
Vol 88 (12) ◽  
pp. 1624-1630 ◽  
Author(s):  
Masakazu Matsumoto ◽  
Tomohiro Fukunaga ◽  
Kaoru Onoe
Keyword(s):  
Calcium Carbonate ◽  
Reactive Crystallization

Development of Decorative Ceramic Glaze from Palm Fiber Ash

2016 ◽  
Vol 690 ◽  
pp. 259-263
Author(s):  
Mohd Al Amin bin Muhamad Nor ◽  
Nur Hawa Hazwani Ya’acob
Keyword(s):  
Calcium Carbonate ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Yellow Colour ◽  
Palm Fiber ◽  
X Ray ◽  
Ceramic Glaze ◽  
Ball Clay ◽  
Lower Temperature ◽  
Decorative Ceramic

Palm fiber ashes are the industrial waste which is abundantly available in Malaysia. In this study, palm fiber ash were used to produce decorative ceramic glaze. The content of minerals in the palm fiber ash were analyzed by using X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF), respectively. The formulations of glaze with different composition of raw materials were studied by adding different amount of calcium carbonate and feldspar. The glaze slurries then coated on ball clay body bisque which was obtained from Kg. Dengir and sintered at 1200 ° C for two hours.The glaze was characterized in term of its physical appearance such as type of glaze and colour. Both glossy and matte glaze produced by using different composition of glaze formulation. The presence of silica minerals (79 %) contributed to glossy surface to the glaze. It is clearly seen that the glossiness of glaze improved by increasing amount of feldspar. Feldspar acts as fluxing agent which form a glassy phase at lower temperature. In addition, the presence of small amount of iron oxide (2.2 wt.%) contributed to brown colour of glaze. An addition of calcium carbonate give effect to the colour of glaze, which change from brown to yellow colour as amount of CaCO3 increased. As a conclusion, the palm fibre ashes were highly suitable to supply abundant and cheap raw materials to produce decorative ceramic glaze.

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