• 공업화학
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• 제30권1호
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• pp.34-38
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• 2019

탄산화 공정을 위한 Ca 추출원으로 시멘트 산업부산물을 사용하였다. ICP와 XRD 분석을 통하여 시멘트 산업부산물은 대부분 CaO와 KCl로 구성되어 있음을 확인하였다. 최적화된 추출용제의 종류 및 농도는 1.5 M of hydrochloric acid이며 최적의 고액비는 0.1 g/mL이었다. 추출 성능 실험 결과를 통해 양이온의 추출효율은 이온 결합 형태 및 용해도에 의존함으로 판단되었다. 또한 추출 공정 후, 첨가물의 종류 및 주입 순서에 따라 선택적으로 양이온이 분리될 수 있음을 확인하였다. pH를 9.5, 13으로 조절하기 위하여 NaOH를 주입하였을 때 불순물과 $Ca(OH)_2$가 침전되었으며, $C_2H_5OH$를 주입한 경우 KCl 형태로 분리된 K가 침전되었다.

• Natural Product Sciences
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• 제28권4호
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• pp.168-180
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• 2022

Ephedra is a genus of the Ephedraceae family and is found in temperate regions, such as Central Asia and Europe. Among the various ephedra species, Ma Huang (Ephedra herb) is derived from the aerial parts of Ephedra sinica S tapf, Ephedra equisetina Bunge, and Ephedra intermedia Schrenk & C.A. Mey. Ma Huang contains various ephedra alkaloids, including (-)-ephedrine, (+)-pseudoephedrine, (-)-norephedrine, (+)-norpseudoephedrine, (-)-methylephedrine, and (+)-methylpseudoephedrine, which are found naturally as single enantiomers, although they can be prepared as racemates. Although the use of Ma Huang in foods is prohibited in Korea, products containing Ma Huang can be imported, and so it is necessary to develop a suitable analytical technique for the detection of Ma Huang in foods. Herein, we report the development of analytical methods for the detection of ephedra alkaloids in products containing Ma Huang. Following sample purification by solid phase extraction, quantitative analysis was performed using ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). Additionally, the enantiomers were successfully separated using HPLC-DAD. We successfully analyzed various food samples, where the ephedra alkaloids were qualitatively and quantitatively determined, and the enantiomers were separated. It is expected that these methods may contribute toward preventing the distribution of illegal products containing Ma Huang.

• Membrane and Water Treatment
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• 제9권6호
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• pp.447-454
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• 2018

Although flotation techniques are often used for the removal of algal particles, the practicality of algae-harvesting technologies is limited owing to the complex and expensive facilities and equipment required for chemical coagulation. Here, we examined the feasibility of an approach to separating algal particles from water bodies without the need for chemical coagulants, depending on the condition of the algae, and to determine the optimal conditions. Using Anabaena sp., a cyanobacterium causes algal blooms in lakes, we stimulated auto-flocculation in algal particles without coagulants and conducted solid-liquid separation experiments of algal particles under various conditions. The six cultivation columns included in our analysis comprised four factors: Water temperature, light intensity, nutrients, and carbon source; auto-flocculation was induced under all treatments, with the exception of the treatment involving no limits to all factors, and algal particles were well-settled under all conditions for which auto-flocculation occurred. Meanwhile, flotation removal of auto-flocculated algal particles was attained only when nutrients were blocked after algae were grown in an optimal medium. However, no significant differences were detected between the functional groups of the extracellular polymeric substances (EPSs) of floated and settled algal particles in the FT-IR peak, which can cause attachment by collision with micro-bubbles.

• 자원리싸이클링
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• 제10권3호
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• pp.23-28
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• 2001

Magnetite가 주성분인 산화철 폐촉매를 이용하여 도금폐수중 아연이온을 pH 2.0이상에서 98.7% 이상 회수하였다. 폐촉매의 포화자화값은 59.4 smug으로 폐수처리후 자기적방법에 의해 고.액분리가 가능하다. 산화철 .폐촉매에 의한 폐수중 아연이온의 회수메카니즘은 pH 3.0-8.5 범위에서는 폐촉매 표면에서 $Zn^{2+}$ 이온의 정전기적 흡착이며 pH 8.5 이상에서는 $Zn(OH)_2$의 침전이라고 생각한다.

• 한국분말재료학회지
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• 제4권2호
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• pp.113-121
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• 1997

The densification of the compacts of Co+32%Cr+20%W+l.5%C, Co+32%Cr+20%W+3.0%C and Co+32%Cr+20%W+4.5%C sintered under $H_2$ gas or vacuum was investigated. The effect of V and B addition on the densification was also investigated. The densification of these compacts were always incomplete regardless of sintering atmosphere, temperature and time. The amounts of oxygen and carbon in compacts sintered in $H_2$ for 3.6ks at 1523K were 0.105~0.160 mass% and 0.33~0.89 mass%, respectively. And those in vacuum were 0.028~0.032% and 0.957~4.08%, respectively. Relative density(Ds) of Co+29%Cr+17%W+3.0%C compact containing 6%V and Co+32%Cr+20%W+2.97%C compact containing 0.03%B were 99 and 100%, respectively, indicating complete densification by solid phase sintering. Victors hardness of sintered compacts containing 6%V or 0.03%B were 632 and 568, showing 50~60% increase in comparison to those without V or B. These results can be explained in terms of oxidation/reduction of oxides and equilibrium pressure of CO in isolated pore, instead of presence of liquid formation and grain boundary separation from pores due to large grain growth.

• 한국응용과학기술학회지
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• 제23권4호
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• pp.340-346
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• 2006

The influences of fluorescence, scattering, and flocculation in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by the spectroscopy of laser induced fluorescence (LIF). The effects of optical properties in scattering media have been found by the optical $parameters({\mu}_s,\;{\mu}_a,\;{\mu}_t)$. Flocculation is an important step in many solid-liquid separation processes and is widely used. When two particles approach each other, interactions of several colloid particles can come into play which may have major effect on the flocculation and LIF process, The value of scattering coefficient ${\mu}_s$ is large by means of the increasing particles of scatterer it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, biopharmaceutical products, laser medicine and application of medical engineering on LIF and coagulation in particle transport mode.

• 환경위생공학
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• 제15권2호
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• pp.75-84
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• 2000

운전 온도 $35^{\circ}C$, 평균 유기물부하 $3.1{\;}kgCOD/m^3/day$ 및 수리학적체류시간 10일에서 혐기성 연속회분식공정에 의한 분뇨처리를 수행하였다. 공정의 평가는 대조 소화조로 완전혼합형의 소화조와 병행하여 수행되었다. 본 실험에서 분뇨는 고농도의 암모니아성 질소와 침전성 고형물을 함유하고 있음에도 불구하고 희석 없이 소화가 가능하였다. 혐기성 연속회분식공정에서 고형물은 급속하게 증가하여 완전혼합형의 대조 소화조에 비하여 소화조내 고형물(biomass)의 농도가 2.4배로 증가하였고, 가스발생량에 있어서도 대조 소화조에 비해 현격한 증가를 보였으며 그 증가율은 205~220%에 달했다. 부가적인 침전 시설이 없이도 혐기성 연속회분식공정의 유출수질이 대조 소화조 보다 높게 나타났는데 상징액 기준으로 휘발성고형물 제거율은 혐기성 연속회분식공정이 대조 소화조 보다 12~14% 높았다. 한편, 혐기성 연속회분식공정의 운전인자로 반응/침강비(R/T ratio)를 조사한 결과 R/T비가 1인 경우가 3의 경우보다 가스발생량, 메탄함량 및 유기물 제거율이 약간 높았으나 큰 차이는 없었다. 위의 실험결과들로부터 혐기성 연속회분식공정은 고농도의 암모니아성 질소와 침전성 유기물을 함유하고 있는 분뇨의 처리에 효과적이고 안정적인 공정으로 판단된다.

• 상하수도학회지
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• 제8권1호
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• pp.1-8
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• 1994

Laboratory experiments were conducted to investigate the effect of digestion temperature on the settleability and dewaterability of anaerobically digested sludge. The digesters were operated at a hydraulic retention time of 20 days with a loading rate of 0.63~0.66kg volatile solids per cubic meter per day at the temperature of $35^{\circ}C$ and $55^{\circ}C$. A mixed primary and secondary municipal sludge was used as a feed. The interface height of the sludge during settling test was recorded to identify settleability. As a measure of dewaterability of the sludge, specific resistance and capillary suction time were also measured with and without chemical conditioning. Higher digestion efficiency was obtained at $55^{\circ}C$ than $35^{\circ}C$. However, the settleability and dewaterability of the sludge at $35^{\circ}C$ were quite higher than those of the sludge digested at $55^{\circ}C$. The optimum dosages of ferric chloride for sludge conditioning were 0.4% and 0.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. The filtrate COD of the sludge digested at $55^{\circ}C$ was higher than at $35^{\circ}C$, which means that poor dewaterability of the sludge result in high filtrate COD.

• 상하수도학회지
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• 제20권5호
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• pp.677-684
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• 2006

Electro-flotation(EF), a novel sludge thickening method, could improve the dewaterability of activated sludge. The gas(microbubbles) generated during EF decreased the solid-liquid separation time below 1/5 of the time required for gravity sedimentation. In addition, over 90% of the sludge volume reduction could be achieved by EF although the settling characteristics of the sludge was very poor. The SRF(specific resistance to filtration) of the thickened sludge by EF was much lower than that of the sludge thickened by gravity sedimentation. The SRF of the thickened sludge decreased exponentially with increase of gas generation rate of the EF system. Gas generation rate could be controlled by varying the current density of the electrode. Degasing of the microbubbles by vigorous mixing of the thickened sludge layer deteriorated the dewaterability of the sludge. Therefore, it is obvious that the gas bubbles entrapped in the thickened sludge play a key role in the observed dewaterability improvement.

• KSBB Journal
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• 제23권2호
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• pp.169-176
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• 2008

The concentration of fresh gel from Aloe vera L. by using ulfrafiltration (UF) process was investigated and analyzed. The two membranes (organic and ceramic) with different molecular weight cut-off (MWCO) and modules (flat sheet and tubular) was used. Under optimum operation conditions, ceramic (zirconium dioxide) tubular membrane with MWCO of 50 kDa resulted in higher flux, less fouling, more turbid, higher total solid, higher polysaccharide and less aloin content. Optimum operation conditions were transmembrane pressure of 1.0 bar, feed velocity of 240 L/hr and temperature of $23^{\circ}C$. Volume concentration factor of aloe gel was 3.13 at permeate flux of $51.1\;L/m^2{\cdot}hr$ after processing time of 1.66 hr. Aloin in fresh aloe gel by UF process was effectively removed as permeate and bioactive polysaccharide content was 2.1 times higher than that of fresh aloe gel. These results allowed a very good level of concentration degree and polysaccharide content. Thus, ultrafiltration process of this study was suitable for the concentration of fresh aloe gel though the aloe concentrate showed both the viscosity decrease and partially separation of liquid layer during storage at $4^{\circ}C$.