• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.540-548
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• 2016

Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO₂. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

• Korean Chemical Engineering Research
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• 제50권3호
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• pp.427-434
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• 2012

Poly (carbonate diol)과 isophrone diisocyanate 그리고 dimethylol propionic acid로 부터 NCO/OH 몰 비를 0.8, 1.1, 1.3으로 각각 조절하여 수분산 폴리우레탄(waterborne polyurethane dispersion, PUD)을 합성하였다. 이 용액에 알카리 금속염인 $LiClO_4$, $NaClO_4$, $KClO_4$를 첨가하여 대전방지용 수분산 폴리우레탄 코팅 용액을 제조하였다. 이 과정에서 첨가되는 알카리 금속염의 첨가량과 종류가 코팅 도막의 표면저항에 미치는 영향을 살펴보았다. 알카리 금속염의 첨가량이 증가될수록 코팅 도막의 표면저항은 감소하였다. 그러나 PUD에 같은 양의 알카리 금속염이 첨가될 경우에는 $LiClO_4$ > $NaClO_4$ > $KClO_4$의 순서로 코팅 도막의 이온 전도도가 우수함을 알 수 있었다. 또한 PUD 내의 NCO/OH 몰 비가 증가함에 따라 코팅 도막의 표면저항이 증가하여 이온 전도도가 감소하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.789-792
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• 2006

The purpose of this study is to investigation the fundamental properties of alkali activated slag of type and concentration of alkali activator. In this paper sodium silicate, sodium carbonate and sodium hydroxide were used as alkaline activator and their concentration were 1, 3, 5 and 7 $Na_2O$ weight percent. The physical properties of alkali activated blast furnace slag cement mortar (AAS) were investigated by flow test and compressive strength. And the hydration properties of AAS characterized by X-ray diffraction and scanning electron microscope. Result show that Alkali activated slag mortar strengths were continuously increased with adding amount and ages. C-S-H were formed to be the main products up to 28days of hydration.

• 펄프종이기술
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• 제43권3호
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• pp.106-112
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• 2011

The effects of alkaline treatment on the WRV, crystalline structure and sheet structure of softwood and hardwood bleached kraft pulp were investigated. Sodium hydroxide and sodium carbonate were used as chemicals for alkaline treatment and two levels of alkali dosage (5%, 10%) were applied respectively. Alkali treated and untreated pulp were refined to three levels (550, 450 and 350 mL CSF). WRV of the alkali treated pulps depended on the alkaline type and concentration. It was found that the crystalline structures of softwood and hardwood pulp were not changed by refining. Sodium carbonate and lower concentration of sodium hydroxide treatment did not caused any modification of cellulose crystalline structure, while higher concentration of sodium hydroxide treatment caused the partial modification of cellulose crystalline structure. Alkaline treatment of hardwood bleached kraft pulp led to the shrinkage of fiber diameter and bulky structure of sheet. Alkaline treatment of softwood bleached kraft pulp did not cause the significant change in fiber shrinkage and bulk of sheet.

• 방사성폐기물학회지
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• 제11권2호
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• pp.85-93
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• 2013

본 연구는 우라늄 변환시설 운전 중에 발생된 우라늄 함유 슬러지를 가열 처리하여 분말 형태로 저장 중인 우라늄 함유 슬러지의 열분해 고체폐기물 (Thermal Decomposed Solid Waste of uranium-bearing sludge : TDSW)을 대상으로 TDSW의 용해, TDSW 질산 용해액의 알카리화에 의한 불순물 제거 및 탄산염 알카리화 용액의 산성화에 의한 U 선택적 제거/회수 특성 등을 규명하였다. TDSW의 용해는 질산용해가 탄산염 산화용해 보다 효과적이었다. 1M 질산에서 TDSW의 약 30wt%가 고체 잔류물로 불용해되었고, TDSW 내 함유 U은 99% 이상이 용해되었다. TDSW의 질산 용해액의 알카리화는 탄산염에 의한 알카리화가 불순물 제거 측면에서 보다 효과적이며, 탄산염 알카리화 (pH 약 9)에서 U과 공용해된 Ca, Al, Zn 및 Fe 등의 $98{\pm}1%$가 제거되었다. 그리고 불순물이 거의 제거된 알카리화 용액 (0.5 M $H_2O_2$ 첨가)의 산성화 (pH 약 3) 에서 U의 99% 이상을 회수할 수 있어 TDSW로부터 U을 선택적으로 제거/회수할 수 있었다.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.416-420
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• 2018

A comprehensive kinetic study has been conducted on dimethyl carbonate synthesis by transesterification reaction of ethylene carbonate with methanol. An alkali base metal (KOH) was used as catalyst in the synthesis of DMC, and its catalytic ability was investigated in terms of kinetics. The experiment was performed in a batch reactor at atmospheric pressure. The reaction orders, the activation energy and the rate constants were determined for both forward and backward reactions. The reaction order for forward and backward reactions was 0.87 and 2.15, and the activation energy was 12.73 and 29.28 kJ/mol, respectively. Using the general factor analysis in the design of experiments, we analyzed the main effects and interactions according to the MeOH/EC, reaction temperature and KOH concentration. DMC yield with various reaction conditions was presented for all ranges using surface and contour plot. Furthermore, the optimal conditions for DMC yield were determined using response surface method.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2339-2358
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• 2022

The review discusses various alternative approaches for spent nuclear fuel (SNF) reprocessing in aqueous carbonate media. The main stages, schemes, and methods of the most well-known and well-described processes for reprocessing SNF and some high-level radioactive waste using carbonate systems developed by research groups in Japan, the United States of America, the Republic of Korea, and the Russian Federation described and compared. The main advantages of such methods are outlined compared to the SNF reprocessing in nitric acid media. The levels of development and proximity of the designed processes to the industrial implementation are shown. The main principle achievements, prospects, and routes for the refinement of such methods for the technology of SNF reprocessing and handling of high-level radioactive waste formulated.

• 한국식품과학회지
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• 제28권1호
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• pp.58-65
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• 1996

탄산나트륨, 탄산칼륨과 이들의 혼합염(탄산나트륨/탄산칼륨=0.7-2.0)이 밀가루의 아밀로그래프에 의한 호화성질과 파리노그래프에 의한 반죽성질을 조사하였다. 알칼리제 혼합염(0.16%)이 국수의 성질에 미치는 영향도 아울러 검토하였다. 소금(0.17%)과 알칼리는 아밀로그래프의 호화개시 온도를 감소시켰고 최고점도를 증가시켰으며 그 효과는 탄산나트륨이 가장 현저하였다. 최고점도는 알칼리의 농도가 증가할수록 증가하였고 동일한 농도에서는 혼합비율에 따른 차이는 없었다. 파리노그래프의 흡수율은 소금에 의하여 감소되었고 알칼리제에는 영향을 받지 않았으나 소금과 알칼리제가 동시에 존재할 때는 소금의 효과가 감소하였다. 소금과 알칼리제는 반죽의 안정도를 크게 증가시켰으며 소금의 효과가 더욱 뚜렸하였다. 그러나 소금의 존재시 알칼리제 단독 또는 혼합 사용하였을 때는 농도에 관계없이 알밀로그람과 파리노그람 특성값은 큰 차이를 보이지 않았다. 알칼리제 혼합염의 첨가에 따라 건면의 황색도와 파쇄력이 증가하였고 파쇄력은 혼합비율 1.0에서 가장 큰 값을 보였다. 삶은 국수의 경우 무게와 부피증가 정도는 알칼리제 혼합염의 첨가에 따라 큰 변화가 없었으나 전단력과 압착력은 혼합비율 1.0에서 가장 높은 값을 보였다.

• 약학회지
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• 제38권4호
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• pp.425-429
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• 1994

The genuine aglycone, 20(S)-protopanaxadiol, obtained from the leaves of Panax ginseng as a result of direct alkaline treatment was isolated and characterized by spectroscopic evidences. The study on the yield of genuine aglycone which is produced from the treatment of some kinds of alkali was carried out. $Ginsenoside-Rh_2$ was synthesized by conjugation of 2,3,4,6-tetra-O-acetyl-${\alpha}$-D-glucopyranosyl bromide to 20(S)-protopanaxadiol in the presence of silver carbonate and cadmium cabonate. The preparation of $ginsenoside-Rh_2$ by this method is a new one which the yield of this saponin can be improved in the mild condition.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1509-1516
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• 2012

Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclusion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixarene in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of $p-tert-calix$[4]arene bearing different sulfonamide moieties were synthesized and their inclusion-extraction parameters were optimized including the calixarene scaffold $\mathbf{3}$ (4 wt %) as the carrier/demulsifier, the commercial kerosene as diluent in membrane, sulphonic acid (0.2 M) and ammonium carbonate (0.4 M) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 rpm), and initial solute concentration (100 mg/L). The selectivity of membrane over more than ten interfering cations was examined and the results reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98-99%.