• 한국결정성장학회지
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• 제15권3호
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• pp.93-98
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• 2005

물에 대한 용해도가 우수한 비정질 탄산칼슘을 이용하여 저온 영역에서 Calcite 단결정을 수열육성 하였다. 비정질 탄산칼슘 제조의 출발원료로는 $CaCl_2$, 및 $Na_2CO_3$를 이용하였으며, 반응온도와 반응시간이 중요한 인자로 작용하였다. 한편, 중량손실법에 의한 비정질 탄산칼슘의 용해도 측정결과 $NH_4NO_3$, 수용액이 Calcite 결정성장에 효과적임을 알 수 있었다. Calcite 결정의 육성에 있어 큰 성장속도를 나타내는 수열조건은 다음과 같다. 즉, 출발원료: 비정질 탄산칼슘, 수열용매: 0.01m $NH_4NO_3$, 반응온도: $180^{\circ}C$, 반응시간: 30일 이었다. 이와 같은 조건하에서 얻어진 Calcite 단결정은 전위밀도: $10^6{\sim}10^7cm^{-2}$, 투과율: $190{\sim}400nm$ 범위에서 약 80%, 복굴절율: $0.17{\sim}0.18$ 이었으며, HCOT 및 $OH^-$ 이온의 혼입에 의한 광학적 흡수가 발생하지 않음을 FT-IR분석 결과로부터 알 수 있었다.

• 한국식품위생안전성학회지
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• 제20권3호
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• pp.128-133
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• 2005

꼬막 패각 회화분을 이용하여 칼슘 보조제로서 사용 할 수 있는 젖산칼슘과 구연산칼슘을 제조하였으며, ammonium chloride process(ACP) ammonium nitrate process(ANP)법을 적용하여 이들의 순도를 높이기 위한 실험을 하였다. 꼬막 패각 회화분을 젖산용액과 구연산용액과 반응시켜 얻은 젖산칼슘과 구연산칼슘의 순도는 각 용액의 농도에 따라 각각 $94.35-96.72\%$와 $87.58-93.06\%$이었다. 꼬막 패각 회화분에 ACP법 혹은 ANP법을 적용하여 정제한 탄산칼슘으로 제조한 젖산칼슘과 구연산칼슘의 순도는 각 용액의 농도에 따라 각각 $99.53-100.34\%$와 $99.32-99.88\%$를 나타내어 꼬막 패각 회화분을 직접 이용하여 제조한 것보다 순도가 상당히 높아졌으며, 식품첨가물공전의 규격기준에 적합한 칼슘제제를 얻을 수 있었다 꼬막 패각 회화분으로 제조한 젖산칼슘과 구연산칼슘의 백색도는 각각 91.8과 92.9이었으나 ACP법 혹은 ANP법을 적용한 경우는 각각 94.8-98.5와 99.4-101.5로서 높은 값을 나타내었다. 따라서 폐기물로 버려지는 꼬막 패각 회화분에 ACP법과 ANP법을 적용하여 정제한 탄산칼슘으로 제조한 젖산칼슘과 구연산칼슘은 순도와 백색도에서 우수한 것으로 판단되었다.

• Korean Chemical Engineering Research
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• 제55권3호
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• pp.279-286
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• 2017

This review paper evaluates different kinds of synthesis methods for calcite precipitated calcium carbonates by using different materials. The various processing routes of calcite with different compositions are reported and the possible optimum conditions required to synthesize a desired particle sizes of calcite are predicted. This paper mainly focuses on that the calcite morphology and size of the particles by carbonation process using loop reactors. In this regard, we have investigated various parameters such as $CO_2$ flow rate, Ca $(OH)_2$ concentration, temperature, pH effect, reaction time and loop reactor mechanism with orifice diameter. The research results illustrate the formation of well-defined and pure calcite crystals with controlled crystal growth and particle size, without additives or organic solvents. The crystal growth and particle size can be controlled, and smaller sizes are obtained by decreasing the Ca $(OH)_2$ concentration and increasing the $CO_2$ flow rate at lower temperatures with suitable pH. The crystal structure of obtained calcite was characterized by using X-ray diffraction method and the morphology by scanning electron microscope (SEM). The result of x-ray diffraction recognized that the calcite phase of calcium carbonate was the dominating crystalline structure.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.219-222
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• 2004

Removal characteristics of Mn and Co was studied from the contaminated solutions via surface reaction with various calcium carbonate (calcite). Synthetic calcium carbonates which has different surface morphology as well as surface areas were prepared by a spontaneous precipitation method and used. Mn and Co removal behavior by the different solid surface demonstrate characteristic sorption behaviors depend on the type of calcite used, such as surface area or surface morphology. Calcium carbonate crystals (mostly calcite) which exhibit complicated surface morphology (c-type) shows strong sorption affinity for Mn and Co removal via sorption than on the a-type or b-type calcite crystals of less complicated surfaces. The applicability of two kinetic models, the pseudo-first-order kinetic equation and the Elovich kinetic model was examined on these sorption behavior. Elovich kinetic model was found more suitable to explain the very early stage adsorption kinetics, while the pseudo-first-order kinetic equation was successfully fitted for the adsorption kinetics after 50 hours.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.773-778
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• 2002

The variance characteristics of the calcium carbonate contents along to the concrete cover depth takes the prediction method of remaining service life of concrete. Calcium carbonate contents were measured by the Thermo Gravimetric/Differential Thermal Analysis method at three point, depth of 0.25cm, 0.75cm, 1.25cm from the surface of concrete. This prediction method contain some assumption that the chemical protection conferred on steel is through a passive protective oxide film which forms on steel in an environment at or above a pH of 10.5$^{4)}$ .

• 약학회지
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• 제12권3_4호
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• pp.41-49
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• 1968

The optimum reaction conditions for the preparation of the precipitated calcium carbonate of an average particle size of 0.05.mu. in diameter was set in which the Box-Wilson Plan was applied. The reaction conditions are as follows; 1) concentration of milk of lime; 6.56% w/w 2) temperature; 14.24.deg. C #) velocity of carbon dioxide introducing; 1.95l/min. The crystal form was found that of calcite in X-ray diffraction analysis. The particle size was determined by the sedimentation volume measurement. The shape was identified by the elctron micro-diffraction pattern and the electron microscopic photographs.

• Journal of Periodontal and Implant Science
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• 제22권2호
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• pp.208-208
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• 1992

• 한국세라믹학회지
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• 제28권3호
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• pp.205-214
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• 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.

• 자연과학논문집
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• 제4권
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• pp.95-102
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• 1991

규산삼석회$(C_3S)$의 수화반응에 있어서 $T1_2CO_3$의 농도변화에 따른 영향에 대해서 Isothermal microcalorimeter 등을 이용하여 조사한 결과, $T1_2CO_3$의 존재로 인하여 $C_3S$의 수화반응은 촉진되고 $C_3S$의 농도가 급격히 감소된다. 또 $T1_2CO_3$의 농도증가로 인해서 수화반응속도도 증가하고 있다. $T1_2CO_3$ 첨가에서 수화된 $C_3S$의 분석결과로는 반응초기에 $CaCO_3$가 나타나고 있으며, $T1_2CO_3$의 촉진작용이 수화반응의 초기에 있어서만 더욱 분명하게 나타나고 있음을 $C_3S$의 비휘발성 수분함량과 수화도로서 알수 있고 $C_3S$ paste와 접촉하고 있는 액상의 조성은 $T1_2CO_3$의 존재로 인하여 $Ca^(++)$이온과 $OH^-$ 이온의 농도가 상당히 변화하고 있음을 알 수 있다.

• 도시과학
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• 제9권2호
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• pp.45-50
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• 2020

The formation characteristics of calcium carbonates are closely related to the durability and mechanical properties of cement-based materials. In this regard, a deep understanding of the reaction pathway of calcium carbonates is critical. Recently, non-classical nucleation theory was summarized and it was presumed that prenucleation clusters are present. The formation of the prenucleation cluster at undersaturated condition (≈ 0.1 ml) in the present study was investigated via electrical characteristics of an electrolytic solution. Calcium chloride dihydrate (CaCl2·2H2O) and sodium carbonate (Na2CO3) were used as starting materials to supply calcium and carbonate sources, respectively. Furthermore, the reaction pathway of calcium carbonates was investigated by time-resolved polarization and depolarization characteristics of the electrolytic solution. The time-resolved polarization and depolarization tests were conducted by switching polarity with an interval of 20 seconds for 1 hr and by measuring the variation of electrical resistance. It can be inferred from the results obtained in the present study that the reactive constituent for the formation of calcium carbonates was mostly consumed in the period possibly associated with the prenucleation and the reaction pathways may be governed by the monomer-addition mechanism.