아라고나이트는 탄산칼슘(CaCO3)의 동질이상 중 하나이며, 해양 생태계를 포함한 다양한 환경에서 생물학적 및 이화학적 침전 과정을 통해 형성된다. 이러한 아라고나이트의 형성 및 성장뿐만 아니라 아라고나이트 내 스트론튬(Sr)과 같은 미량원소의 치환 특성은 화학종의 농도와 온도와 같은 핵심 인자들에 의해 많은 영향을 받는다. 본 연구에서는 해양 생태계와 유사한 용액 온도와 아라고나이트에 대한 이 용액의 다양한 포화도 조건에서 아라고나이트 내 Sr 병합 특성이 규명되었다. 반응 용액의 주입속도(0.085-17 mL/min), 반응 용액의 이온 농도([Ca]=[CO3] 0.01-1M), 혼합 용액의 온도(5-40 oC)의 다양한 실험 조건에서 컨스턴트-에디션 (constant-addition) 방법을 통해 순수한 아라고나이트가 합성되었다. 또한, 모든 Sr 병합 실험 조건(0.02-0.5 M, 15-40 oC)에서도 순수한 아라고나이트가 형성되었다. 합성된 아라고나이트의 결정도와 결정크기는 포화도 및 온도가 증가함에 따라 상대적으로 더 크게 증가하며 아라고나이트 결정이 더 많이 성장하였음을 지시하였다. 그러나 BET-비표면적을 이용하여 계산된 결정성장속도는 결정 형상 변화에 크게 영향을 받는 것으로 나타나 해석에 주의가 요구된다. 아라고나이트 내 Sr의 분배계수(KSr)는 반응이온의 농도가 0.02에서 0.5 M로 증가할 때 2.37에서 1.57로, 온도가 15에서 40˚C로 증가할 때 1.90에서 1.54로 감소하였으며, 모든 조건에서 KSr 값이 1보다 높게 관찰되었다. 이러한 결과는 KSr가 결정성장속도와 역의 상관관계로서 아라고나이트 내 Sr 병합이 호정성 관계임을 나타낸다.

In the current study, MIL-101(Cr)-SO3H[HCl] as metal-organic frameworks (MOFs) was fabricated via a hydrothermal method. The physicochemical properties of the synthesized material were characterized using XRD, FT-IR, FE-SEM, TEM, and BET surface area analysis. The XRD diffraction pattern of the prepared MIL-101(Cr)-SO3H[HCl] was similar to previously reported patterns of MIL-101(Cr) type materials, indicating successful synthesis of MIL-101(Cr)-SO3H[HCl]. The FT-IR spectrum revealed the molecular structure and functional groups of the synthesized MIL-101(Cr)-SO3H[HCl]. FE-SEM and TEM images indicated the formation of rectangular parallelopiped structures in the prepared MIL-101(Cr)-SO3H[HCl]. Furthermore, the EDS spectrum showed that the synthesized material consisted of the elements of Cr, O, S, and C. The fabricated MIL-101(Cr)-SO3H[HCl] was then employed as an adsorbent for the removal of Sr2+ and Cs+ from aqueous solutions. The adsorption kinetics and adsorption isotherm models were studied in detail. The maximum adsorption capacities of MIL-101(Cr)-SO3H[HCl] for Sr2+ and Cs+ according to pH (3, 5.3∼5.8, 10) were 35.05, 43.35, and 79.72 mg/g and 78.58, 74.58, and 169.74 mg/g, respectively. These results demonstrate the potential of the synthesized MOFs, which can be effectively applied as an adsorbent for the removal of Sr2+ and Cs+ ions from aqueous solutions and other diverse applications.

Experimental program was conducted for hydration heat evaluation of concrete using strontium based phase change material (PCM). Adiabatic temperature rise test was investigated for four days. In results, concrete with strontium based PCM has about 20 percent lower hydration heat than ordinary one.

In this study, as a fundamental study for the remediation of the radionuclides-contaminated soil, the adsorption of cobalt, strontium, and cesium on natural soil and kaolin were experimently investigated and adsorption characteristics were evaluated by using several adsorption kinetic and isotherm models. The pseudo-first-order kinetic model (PFOM), pseudo-second-order kinetic model (PSOM), one-site mass transfer model (OSMTM), and two compartment first-order kinetic model (TCFOKM) were used to evaluate the kinetic data and the pseudo-second-order kinetic model was the best with good correlation. The adsorption equilibria of cobalt, strontium, and cesium on natural soil were fitted successfully by Redlich-Peterson and Sips models. For kaolin, the adsorption equilibria of cobalt, strontium, and cesium were fitted well by Redlich-Peterson, Freundlich, and Sips models, respectively. The amount of adsorbed radionuclides on natural soil and kaolin was in the order of cesium > strontium > cobalt. It is considered that these results could be useful to predicting the adsorption behaviors of radionuclides such as cobalt, strontium, and cesium in soil environments.

본 연구에서는 스트론튬계 잠열재를 사용한 저발열 콘크리트를 레미콘 배처플랜트에서 시험생산한 후 생산된 콘크리트의 기초성능 및 모의부재에 의한 수화온도 특성을 평가하였으며, 그 결과 스트론튬계 잠열재를 사용한 저발열 콘크리트의 현장적용 가능성을 확인하였다. 이후 스트론튬계 잠열재를 사용한 콘크리트를 실제 교각 건설현장에 적용하였으며, 적용부재에 대한 수화열 해석 및 타설 콘크리트의 성능평가 결과 수화열 및 온도균열 저감효과가 우수한 것으로 나타나, 향후 대형 매스콘크리트의 수화열 및 온도균열 저감대책으로서 활용이 기대된다.

The adsorption behaviors of strontium and cesium ions on fly ash, natural zeolites, and zeolites synthesized from fly ash were investigated. The zeolites synthesized from fly ash had greater adsorption capabilities for strontium and cesium ions than the original fly ash and natural zeolites. The maximum adsorption capacity of synthetic zeolite for strontium and cesium ions was 100 and 154 mg/g, respectively. It was found that the Freundlich isotherm model could fit the adsorption isotherm. The distribution coefficients (Kd) for strontium and cesium ions were also calculated from the adsorption isotherm data. The distribution coefficients decreased with increasing equilibrium concentration of strontium and cesium ions in solution. By studying the removal of cesium and strontium ions in the presence of calcium, magnesium, sodium, potassium, sulfate, nitrate, nitrite, and EDTA (in the range of 0.01 - 5 mM) it was found that these coexistence ions competed for the same adsorption sites with strontium and cesium ions.