• 한국광물학회지
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• 제31권2호
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• pp.67-73
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• 2018

본 연구는 acid bake-water leaching system (AWS)를 이용하여 Au 정광으로부터 경제적이고 친환경적인 유용금속 용출을 위하여 황산염 용매제의 적용성을 파악하는 것이다. AWS 실험은 전기로를 이용하여 다양한 baking 온도($100^{\circ}C{\sim}500^{\circ}C$)와 황산염 용매제($H_2SO_4$, $K_2SO_4$, $(NH_4)_2SO_4$, $MgSO_4$, $CaSO_4$) 조건에서 수행하였다. Baking 온도가 $400^{\circ}C$까지 증가할수록 유용금속의 용출률은 증가하였다. 용출시간에 따른 AWS 실험결과, 최대 용출률 조건은 $(NH_4)_2SO_4$ 용매제이었다. 본 연구를 통하여 $(NH_4)_2SO_4$ 용매제가 AWS를 이용한 유용금속 용출에 있어 효과적인 용매제로 사용가능함을 입증하였다.

• Food Science and Biotechnology
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• 제15권3호
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• pp.482-484
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• 2006

The antioxidant activity of Bacillus polyfermenticus SCD was studied by partially purified culture extracts using various methods: ammonium sulfate precipitation, adsorption to Diaion HP-20 columns using polar solvents, and extraction using non-polar solvents. The 1,1-diphenyl-2-picyrylhydrazyl (DPPH) radical scavenging activity of these partially purified fractions was then investigated. The precipitate isolated using 75%-saturated ammonium sulfate was shown to contain about 77.2% DPPH radical scavenging activity. Using the Diaion HP-20 resin adsorption method, the fraction obtained using 60% ethanol and 60% methanol possessed 76.7 and 89.5% DPPH radical scavenging activity, respectively. Fractions obtained by extracting with the non-polar solvents 80 mg/mL chloroform, 80 mg/mL n-hexane, 80 mg/mL ethyl acetate, and 80 mg/mL butanol contained 68.4, 75.0, 70.7, and 87.5% DPPH radical scavenging activity, respectively. Further study is needed to characterize the antioxidant substance(s) released by B. polyfermenticus SCD cultures.

• 공업화학
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• 제5권5호
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• pp.779-785
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• 1994

양이온 색소인 thionin(Th)과 음이온 계면활성제인 sodium dodecyl sulfate(SDS) 사이의 상호작용을 흡수 spectra로 고찰하였다. 임계미셀농도(critical micelle concentration, CMC)보다 훨씬 낮은 premicellar 영역(S/D=10, 80 및 160)에서 온도가 증가함에 따라 몰 흡광계수비가 증가하거나 감소함을 볼 수 있으며, S/D=160에서 Th-SDS계의 다분자 회합체가 생성하는 가장 안정한 온도 범위는 $60^{\circ}C$ 이하임을 알 수 있었다. 한편 Th-SDS계에 첨가한 무기염 및 유기용매의 농도가 증가함에 따라 ${\gamma}$-band와 J-band는 감소하나 ${\alpha}$-band는 오히려 증가하는 경향이 나타났다. 이들의 ${\alpha}$-band의 증가 순서는 무기염의 경우 $Cl^-$>$ClO{_4}{^-}$>$SO{_4}{^{2-}}$>$NO{_3}{^-}$로 나타나며, 유기용매인 경우는 2-propanol>ethanol>methanol>ethylene glycol로 나타남을 알 수 있다.

• 한국결정학회지
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• 제5권1호
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• pp.33-38
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• 1994

Hen egg white Iysozyme과 equine serum albumin을 모델 단백질로 하여 'heterogeneous' vapor diffusion실험을 수행하였다. 즉, droplet과 reseroir용액에 각각 다른 침전제를 사용하여 vapor diffusion에 의하여 평형에 이르도록 하였다. 실험 결과는 NSI 혹은 ammonium sulfate 대신 polyethylene glycol이 reservoir 용액에 포함되므로써 droplet과 reservoir 용액 사이의 평형 속도가 감소되는 것을 보여 주었다. Heterogeneous vapor diffusion 법을 통하여 reservoir용액에 포함된 이온성 염과 비이온성 침전제의 양을 적절히 조절하여 평형속도를 조절할 수 있음을 보였다.

• KSBB Journal
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• 제8권1호
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• pp.75-82
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• 1993

The inhibitory effect of cacao bean husk (CBH) extract on glucosyltransferase(GTasc) from Streptococcus mutans B13 was investigated. Water solube extract from CBH showeda sarong inhibitory effect (88-89%) on GTase from Streptococcus mutans Bl3. GTase inhibitors from sequential extraction by hot water or water-methanol had the strongest inhibition. Sources, fermentation, and types of solvents and fumigation processes did not influence the effect. These active compounds proved to be polyphones through acid hydrolytic analysis of the precipitates by ammonium sulfate or ethanol and proteinase K. It was also confirmed by additional column chromatography of Sephadex G-50, Sephadex LH-20 and DEAE-Sephdex A-50.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.1007-1012
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• 2008

Spray pyrolysis has been found as an excellent method for the preparation of mesoporous barium sulfate at higher temperature. Ethylene glycol, a reducing agent, and solvents had good inhibition effect for the preparation of $BaSO_4$ nano particles. The $BaSO_4$ solution was sprayed at 500 & 800 ${^{\circ}C}$ using different solvents such as methanol, ethanol, propanol and n-butyl alcohol. $N_2$ adsorption-desorption isotherm revealed that $BaSO_4$ is micropore free, possessing narrow mesopores size distribution and high BET surface areas of 72.52 $m^2\;g^{-1}$ at 800 ${^{\circ}C}$ using propanol as an additive. Scanning electron microscopy (SEM) indicates that the morphology of $BaSO_4$ nano material shows uniform shell like particles. Transmission electron microscopy (TEM) proved that the resulting BaSO4 nano particles were uniform in size and the average particle size was 4-8 nm. The surface functionality and ethylene glycol peaks were assessed by Fourier transform infrared resonance (FTIR) spectroscopy. Low intensity ethylene glycol specific absorption peak was observed in propanol which proved that propanol had good inhibition effect on the structural morphology of nano particles.

• Journal of Microbiology and Biotechnology
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• 제8권5호
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• pp.449-454
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• 1998

A thennostable chitosanase was purified from Bacillus sp. KFB-C108, by fractionation of 30 to 70% saturation with ammonium sulfate, DEAE-Toyopearl chromatography, Butyl-Toyopearl chromatography, and TSK-Gel HW-55F gel filtration. The purified enzyme showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis, and the molecular weight was estimated to be 48 kDa. The enzyme degraded soluble chitosan and colloidal chitosan, but did not degrade glycol chitosan, chitin, and the other compounds investigated. There was no effect on the chitosanase activity by treatment with chelating agents, alkylating agents, and various metals investigated, and only cobalt ions inhibited the activity. Optimum temperature and pH were $55^{\circ}C$ and 6.5, respectively. The enzyme was stable after heat treatment at $80^{\circ}C$ for 10 min or $70^{\circ}C$ for 30 min and fairly stable in several organic solvents as well. Chitosan was hydrolyzed to $(GlcN)_4$as a major product by incubation with the enzyme.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.361-367
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• 2020

Recently, layered nickel-rich cathode materials (NCM) have attracted considerable attention as advanced alternative cathode materials for use in lithium-ion batteries (LIBs). However, their inferior surface stability that gives rise to rapid fading of cycling performance is a significant drawback. This paper proposes a simple and convenient coating method that improves the surface stability of NCM using sulfate-based solvents that create artificial cathode-electrolyte interphases (CEI) on the NCM surface. SO_x-based artificial CEI layer is successfully coated on the surface of the NCM through a wet-coating process that uses dimethyl sulfone (DMS) and dimethyl sulfoxide (DMSO) as liquid precursors. It is found that the SO_x-based artificial CEI layer is well developed on the surface of NCM with a thickness of a few nanometers, and it does not degrade the layered structure of NCM. In cycling performance tests, cells with DMS- or DMSO-modified NCM811 cathodes exhibited improved specific capacity retention at room temperature as well as at high temperature (DMS-NCM811: 99.4%, DMSO-NCM811: 88.6%, and NCM811: 78.4%), as the SO_x-based artificial CEI layer effectively suppresses undesired surface reactions such as electrolyte decomposition.

• KSBB Journal
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• 제26권1호
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• pp.49-56
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• 2011

Volatile components of crude fucoidan and its raw material, Undaria pinnatifida sporophylls were identified by GC/MSD analysis, and the effects of a combined method of solvent extraction and drying (hot-air drying or spray drying) on deordorization of fucoidans were examined. The major components of seaweed smell (odor) in crude fucoidan and Undaria pinnatifida sporophylls were identified as alkanes (octadecane, heptadecane, tetradecane) and acids (hexadecanoic acid, oleic acid). Solvent extraction and drying were combined for the deordorization of fucoidans: hot-air drying/deordorization process (HDDP) and spray drying/deordorization process (SDDP). The deordorization effects of solvent extraction using solvents including water, ethanol, and acetone were investigated. Among the tested solvents, ethanol was selected as a deordorization solvent, because the seaweed smell and taste were mostly lowered by ethanol extraction followed by drying. In addition, HDDP and SDDP were compared, showing that SDDP gave higher sensory characteristics than HDDP. When the crude fucoidan was treated by ethanol extraction for 30 min followed by SDDP, approximately 60% of off-flavor components of crude fucoidan was removed based on GC/MSD peak area, and the total sugar and sulfate contents and APTT-anticoagulant activity significantly increased compared to crude fucoidan. In conclusion, SDDP after ethanol treatment was proposed and established as a deordorization process for fucoidan preparation.

• 한국응용과학기술학회지
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• 제34권2호
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• pp.210-216
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• 2017

선박엔진에서 발생하는 NOx 및 SOx 제거용 스크러버 폐세정액에 포함되어 있는 저농도상의 질산 및 황산이온을 비료상 물질로 회수하고자 하였다. 본 연구에서는 네 가지 유기용매를 적용하여 선택적으로 추출하여 회수하는 방법을 시험하였다. 아세톤과 메틸알콜을 이용하여 추출한 질산암모늄과 디에틸에테르와 에틸알콜을 적용한 황산암모늄의 시료를 적외석흡수분광법(IR)을 이용하여 분석한 결과, 상용제품과 거의 동일한 구성성분으로 나타났다. 이때 폐수로부터의 회수율은 최대 89%와 80%까지 각각 얻을 수 있었다. 따라서 배기가스 스크러버에 잔존해있는 질산이온과 황산이온에 대한 회수는 사용하는 용매의 선택도 및 용해도가 핵심적인 요소인 것으로 판단된다.