• Title/Summary/Keyword: Vaterite

Search Result 36, Processing Time 0.03 seconds

Synthesis of Vaterite Powders with a Spherical Shape by the Precipitation Method (침전법에 의한 구형 Vaterite분말의 합성)

  • 윤봉구;신대용;한상목
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.12
    • /
    • pp.1208-1212
    • /
    • 2003
  • CaCO$_3$ powders were synthesized by aqueous solution reaction of CaC1$_2$ㆍ2$H_2O$-(NH$_4$)$_2$CO$_3$ system with NH$_4$OH at 45$^{\circ}C$ and pHs 8, 9, 10, and 11 and in the concentration range of 0.1∼5 M and its polymorphism, morphology and size were investigated. In order to investigate the influence of pH on nucleation, pH was adjusted before and after reaction respectively. When pH was adjusted after reaction a formation ratio of vaterite was increased with increasing pH and concentration but vaterite was formed with calcite. But, when pH was adjusted before reaction, the formation rate of vaterite was increased with increasing pH and concentration. resulting in a phase-pure vaterite with a spherical shape and 2∼5 $\mu\textrm{m}$ in size. It was found that solubility of alkaline vaterite was decreased with increasing OH- ions in the high pH solution. When pH was adjusted before nucleation in the high concentration range, in particular, decreasing of solubility disturbed transformation of initially formed numerous vaterite to calcite.

Effect of Aspartic Acid and Lysine on Polymorphism of Calcium Carbonate Crystal Formed by Gas-Liquid Reaction (기액반응에서 형성된 탄산칼슘 결정의 다형성에 미치는 Aspartic acid와 Lysine의 영향)

  • Song, Seong-Moon;Seong, Back-In;Koo, Ji-Hoi;Kim, In-Ho
    • Korean Chemical Engineering Research
    • /
    • v.49 no.1
    • /
    • pp.109-113
    • /
    • 2011
  • Crystallization of calcium carbonate were performed by adding aspartic acid and lysine into $CaCl_2$ solution for understanding biomineralization in gas-liquid reaction of $NH_4HCO_3$ and $CaCl_2$. Proportion between calcite and vaterite of calcium carbonate crystals was identified by changing conditions such as reaction time, addition amount of aspartic acid, lysine, $CaCl_2$, and $NH_4HCO_3$. FT-IR(Fourier Transform Infrared spectroscopy) instrument was used to perform analysis of vaterite ratio. Under the condition of $NH_4HCO_3$ 10 g and no additive, an increase of vaterite crystal changed to a decrease around 0.15 M $CaCl_2$. Then it largely increased at 0.25 M $CaCl_2$, after vaterite proportion was rising again at 0.20 M $CaCl_2$. In contrast to that, vaterite crystal continuously decreased to 0.2 M $CaCl_2$, and increased from 0.25 M $CaCl_2$ with 20 g $NH_4HCO_3$. Vaterite crystals were observed to be a maximum after 2days with lysine addition, but $CaCO_3$ vaterite crystals showed minimum with aspartic acid.

Production of Vaterite Type Calcium Carbonate by using Oyster Shell Waste with Lysine (라이신 첨가에 의한 폐 굴껍질 이용 vaterite형 탄산칼슘 제조)

  • Bak, Young-Cheol
    • Korean Chemical Engineering Research
    • /
    • v.59 no.1
    • /
    • pp.118-126
    • /
    • 2021
  • The experiments to produce the vaterite type calcium carbonate were conducted for using the waste oyster shell as the recycling resources. Firstly, the oyster shell were calcinated at 800 ℃ for 24 h. Calcinated oyster shell were reacted with the nitric acid solution, and were diluted to 0.1 M Ca(NO3)2 solution. This solution was mixed with 0.1 M Na2CO3 contained 0.1 mol lysine/1 mol CaO at 20 ℃ and 600 rpm mixing condition for 1 h. The reaction products were identified to vaterite type calcium carbonate (84.5% vaterite, 15.5% calcite) by XRD and SEM analysis. Mean particle diameter was 6.87 ㎛, and the lysine content in calcium carbonate was analyzed to 0.1%.

Quntitative Analysis of Calcium Carbonate Polymorphs by Peak Area of XRD (XRD 피크 면적을 이용한 탄산칼슘 결정 형태의 정량분석)

  • Bak, Young-Cheol
    • Korean Chemical Engineering Research
    • /
    • v.60 no.4
    • /
    • pp.564-573
    • /
    • 2022
  • Calcium carbonate (CaCO3) exhibits three polymorphs: calcite with arhombohedral, vaterite with a spherical, and aragonite with a needle-like structure. Qualitative and quantitative analyses of the morphology of CaCO3 are very important to investigate the synthesis of single-crystal vaterite and aragonite. In this work, the polymorphs of calcium carbonate were quantitatively analyzed using XRD. Pure vaterite and pure aragonite were synthesized and the peak distribution of a single phase was analyzed. The vaterite fraction of a mixture of calcite and vaterite was calculated based on the intensity of a specific diffraction peak, and compared to the results based on the peak area. The mean value of fsV (the correction factor for the peak area of vaterite) was 0.654. The phase analysis of calcite-aragonite mixtures was performed, and the mean value of fsA (the correction factor for the peak area of aragonite) was obtained as 0.6713. Using these factors, Eq. (24)~Eq. (32) for the quantitative analysis based on the total peak area of XRD were derived to calculate the phase contents of ternary phase CaCO3. And three-component XRD section was defined considering overlapping sections.

Effect of Agitation and Additive on the Vaterite Contents of Precipitated Calcium Carbonate from Oyster Shell Waste (폐 굴껍질 이용 침강성 탄산칼슘 제조에서 교반속도와 첨가제가 Vaterite 함유량에 미치는 영향)

  • Young-Cheol Bak
    • Clean Technology
    • /
    • v.29 no.2
    • /
    • pp.95-101
    • /
    • 2023
  • An experiment was conducted to produce vaterite-type precipitated calcium carbonate from waste oyster shells in order to use them as recyclable resources. Calcined oyster shells containing calcium oxide as their main component were prepared at a temperature of 800℃ for 24 h. The oyster shells were dissolved in nitric acid or hydrochloric acid solution to make 0.1 M calcium nitrate or calcium chloride aqueous solution, and a carbonation reaction was performed using a 0.1 M sodium carbonate aqueous solution under various experimental conditions, which included varying the amount of aspatic acid additive, the amount of NH4OH added, the reaction time, the reaction temperature, the stirring speed, and the type of dissolved acid. The XRD, SEM, and size distributions were analyzed and the vaterite content was calculated. Spherical precipitated calcium carbonate with a vaterite content of 95.9% was synthesized by adding 0.1 mol aspatic acid/1 mol CaO and 2 cm3 of NH4OH, and reacting for 1 h at 25℃ while stirring at 600 rpm. The average particle diameter was found to be 12.11 ㎛. Calcium carbonate contatining high vaterite is used as high value added calcium carbonate for medical, food, inke additiver, etc.

Effect of Temperature on the Formation of Vaterite in Ca(OH)2-CH3OH-H2O-CO2 System (Ca(OH)2-CH3OH-H2O-CO2계에서 바테라트의 생성에 미치는 반응온도의 영향)

  • Park, Jong-Lyuck;Choi, Sang-Kuen;Kim, Byoung-Gon;Lee, Jae-Jang
    • Journal of the Korean Ceramic Society
    • /
    • v.39 no.12
    • /
    • pp.1143-1148
    • /
    • 2002
  • Precipitated calcium carbonate is one of the most versatile mineral fillers and is consumed in an wide range of products including paper, paint, plastics, rubber, textiles, sealants, adhesives and printing ink and can be produced by several methods. Calcium carbonate has three isomorphism; vaterite, aragonite and calcite, with numerous variations of morphology in the natural mineral or organism. Formation process of vaterite in the reaction of system $Ca(OH)_2-CH_3OH-H_2O-CO_2$ were investigated by measuring the electrical conductivity, $Ca^{2+}$ ion concentration, pH in the slurries and by means of X-ray diffraction and electron microscopic observation. It was clearly established that the reaction temperature is important variable in the carbonation process; in general over 50${\circ}C$, the vaterite was precipitated with the calcite and aragonite. SEM and XRD observations revealed that the vaterite formation could be prepared the temperature range of 40 to 50${\circ}C$ and mean size of particles in this range is controlled from 0.5 to 0.8 ${\mu}m$.

Formation and Crystallization of Calcium Carbonate in $C_2H_5OH-Ca(OH)_2-CO_2$ System by Ceramic Bubble Plate Reactor. (Ceramic Bubble Plate를 이용한 $C_2H_5OH-Ca(OH)_2-CO_2$계의 탄산칼슘 생성 및 결정화 연구)

  • Ahn, Ji-Whan;Park, Chan-Hoon
    • Resources Recycling
    • /
    • v.5 no.3
    • /
    • pp.56-64
    • /
    • 1996
  • C,H,OH system is widely used for producing synthetic beverages and pharmaceuticals. Calcium hydroxide suspension was used to callhol the morphology of calcium carbonate, and the charactenstics of the formahan and crystsllizatian of calcium cilrbonate by adding ethylenc glycol were determined A reaclor was made with attaching a ceramic bubble plate, and lhe eleclrical conductivity was continously monitored during the rcaction with CO, gas. A part of the suspension was separated and powdered at the transition point. XRD and electron microscopic observation showed that the intermedmte and final products were vilterite, ;~r;lganite and calcite. In this study, the volumc of the ethylene glycol added to CH,OH was fixed a1 10 vol\ulcornerh. The valumc of the suspension was 500 ml, and the changes oi characteristics were shdied along with variims cnntents(l0-50 g) of calcium hydroxide. Except m the case of 10 g of calcium hydroxide at the crystallization stagc, all of products showed gelation. Tne marc the calcium hydroxide the shorter the formation time. Alsa. the farmalion of spherical valcrile ivas obsemcd when 30 g Ca(OH), was added. Tne vaterite(a compound material) can bc synthesised under alnbienl pressure and lempcmhre m a C,H,OH system by morphology control. Even though the vateritc was meta-stable phasc and could bc changed to calcitc easily, the stable and spherical vateritc was observed by using G5 glass fillers and vacuum dricrs.

  • PDF

Synthesis and Shape Control of Calcium Carbonate Fine Powders by Liquid-Gas Reaction Method (액상-기상 반응법에 의한 탄산칼슘 미분말의 합성과 형상제어)

  • 민경소;최상흘
    • Journal of the Korean Ceramic Society
    • /
    • v.28 no.3
    • /
    • pp.205-214
    • /
    • 1991
  • Calcium carbonate fine powders were synthesized by blowing CO2 gas in CaO or Ca(OH)2 suspension, and the shapes of powders obtained were examined for each synthetic condition. When water was used as a solvent, ultrafine calcite powders with the average size of∼0.03$\mu\textrm{m}$ were obtained. When synthesized using methanol as a solvent, amorphous phase and spherical vaterite phase were obtained by suction filtering and non-filtering, respectively. Reaction did not occured in ethanol medium, but spherical vaterite phase was obtained by adding ethylene glycol in ethanol.

  • PDF

CaCO3 Biomineralization in Microfluidic Crystallizer (미세유체 결정화기를 이용한 탄산칼슘 Biomineralization)

  • Seo, Seung Woo;Ko, Kwan Young;Lee, Chang Soo;Kim, In Ho
    • Korean Chemical Engineering Research
    • /
    • v.51 no.1
    • /
    • pp.151-156
    • /
    • 2013
  • Crystallization of $CaCO_3$ is practiced on a polymethylsiloxane (PDMS) - based microfluidic system. Liquid- liquid reaction was investigated by mixing calcium chloride ($CaCl_2$) and sodium carbonate ($Na_2CO_3$) solution to crystallize $CaCO_3$. Aspartic acid (Asp) was added to investigate the morphology change such as vaterite and calcite. Suitable ratio of $Na_2CO_3$ and $CaCl_2$ was searched for initial seed formation. Christmas tree model was used as microfluidic device to form concentration gradient of $Na_2CO_3$ and $CaCl_2$. After observing microfluidic channel by using optical microscope, we found that seeds of $CaCO_3$ were formed under the condition that the ratio of $Na_2CO_3$ and $CaCl_2$ was 2:1. Morphology of crystals were also observed as $CaCO_3$ crystals grow. When Asp was added, vaterite crystal was more frequently found in two morphologies (vaterite and calcite) and seed formation and crystal growth were inhibited.

A Study on Cementation Reaction Mechanism for Weathered Granite Soil and Microbial Mixtures (화강풍화토와 미생물 혼합물의 고결 반응 메카니즘)

  • Oh, Jongshin;Lee, Sungyeol;Kim, Jinyung;Kwon, Sungjin;Jung, Changsung;Lee, Jaesoo;Lee, Jeonghoon;Ko, Hwabin;Baek, Wonjin
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.61 no.6
    • /
    • pp.103-110
    • /
    • 2019
  • The purpose of this study is to investigate the reaction mechanism of soil and bacteria solution by various mixing ratios. For this purpose, in order to understand the reaction mechanisms of microorganisms and weathered granite soil, the tests were carried out under various mixing ratios additives such as soil, bacteria solution, $Ca(OH)_2$ and fixture. The test results from this study are summarized as follows. Firstly, the reaction between the bacteria solution and fixture produced a precipitate called vaterite, a type of silicate and calcium carbonate. Secondly, as a result of SEM analysis, the resulting precipitates generated from the test results using the specimens with various mixing ratios except SW condition and the irregular spherical microscopic shapes were formed in the size of $150{\mu}m$ to $20{\mu}m$. In addition, it can be seen that the bacteria solution and the fixture reacted between the granules to form an adsorbent material layer on the surface, and the microorganisms had a biological solidifying effect when the pores are combined into hard particles. Finally, The XRD analysis of the sediment resulting from the reaction between the microorganism and the deposit control agent confirmed the presence of a type of calcium carbonate ($CaCO_3$) vaterite, which affects soil strength formation, as well as silicate($SiO_2$).