• Korean Chemical Engineering Research
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• 제53권6호
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• pp.682-689
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• 2015

A two-step process was investigated for pretreatment and fractionation of rice straw. The two-step fractionation process involves first, soaking rice straw in aqueous ammonia (SAA) in a batch reactor to recover lignin-rich hydrolysate. This is followed by a second-step treatment in a fixed-bed flow-through column reactor to recover xylo-oligomer-rich hydrolysate. The remaining glucan-rich solid cake is then subjected to an enzymatic process. In the first variant, SAA treatment in the first step dissolves lignin at moderate temperature (60 and $80^{\circ}C$), while in the second step, hot-water treatment is used for xylan removal at higher temperatures ($150{\sim}210^{\circ}C$). Under optimal conditions ($190^{\circ}C$ reaction temperature, 30 min reaction time, 5.0 ml/min flow rate, and 2.3 MPa reaction pressure), the SAA-hot-water fractionation removed 79.2% of the lignin and 63.4% of the xylan. In the second variant, SAA was followed by treatment with dilute sulfuric acid. With this process, optimal treatment conditions for effective fractionation of xylo-oligomer were found to be $80^{\circ}C$, 12 h reaction time, solid-to-liquid ratio of 1:12 in the first step; and 5.0 ml $H_2SO_4/min$, $170^{\circ}C$, and 2.3 MPa in the second step. After this two-step fractionation process, 85.4% lignin removal and 78.9% xylan removal (26.8% xylan recovery) were achieved. Use of the optimized second variant of the two-step fractionation process (SAA and $H_2SO_4$) resulted in enhanced enzymatic digestibility of the treated solid (99% glucan digestibility) with 15 FPU (filter paper unit) of CTec2 (cellulase)/g-glucan of enzyme loading, which was higher than 92% in the two-step fractionation process (SAA and hot-water).

• Journal of Applied Biological Chemistry
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• 제51권6호
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• pp.262-271
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• 2008

Natural abundances of stable isotopes of nitrogen and carbon (${\delta}^{15}N$ and ${\delta}^{13}C$) are being widely used to study N and C cycle processes in plant and soil systems. Variations in ${\delta}^{15}N$ of the soil and the plant reflect the potentially variable isotope signature of the external N sources and the isotope fractionation during the N cycle process. $N_2$ fixation and N fertilizer supply the nitrogen, whose ${\delta}^{15}N$ is close to 0%o, whereas the compost as. an organic input generally provides the nitrogen enriched in $^{15}N$ compared to the atmospheric $N_2$. The isotope fractionation during the N cycle process decreases the ${\delta}^{15}N$ of the substrate and increases the ${\delta}^{15}N$ of the product. N transformations such as N mineralization, nitrification, denitrification, assimilation, and the $NH_3$ volatilization have a specific isotope fractionation factor (${\alpha}$) for each N process. Variation in the ${\delta}^{13}C$ of plants reflects the photosynthetic type of plant, which affects the isotope fractionation during photosynthesis. The ${\delta}^{13}C$ of C3 plant is significantly lower than, whereas the ${\delta}^{13}C$ of C4 plant is similar to that of the atmospheric $CO_2$. Variation in the isotope fractionation of carbon and nitrogen can be observed under different environmental conditions. The effect of environmental factors on the stomatal conductance and the carboxylation rate affects the carbon isotope fractionation during photosynthesis. Changes in the environmental factors such as temperature and salt concentration affect the nitrogen isotope fractionation during the N cycle processes; however, the mechanism of variation in the nitrogen isotope fractionation has not been studied as much as that in the carbon isotope fractionation. Isotope fractionation factors of carbon and nitrogen could be the integrated factors for interpreting the effects of the environmental factors on plants and soils.

• 상하수도학회지
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• 제18권6호
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• pp.807-813
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• 2004

Wastewater was treated by two different treatment processes; activated sludge process and advanced wastewater treatment process (KNR process) using lab-scale experiment. Two treated wastewater showed good treatment efficiency of organic matter removal, up to 90% removal. Nitrogen and phosphorus were not effectively removed though activated sludge process, while KNR process showed good removal efficiency of nitrogen and phosphorus; 56% nitrogen removal and 95% phosphorus removal. KNR process showed better removal efficiency of organic matter, nitrogen, and phosphorus compared to activated sludge process. Organic matter characterization was tracked though measurement of UV scan, SUVA, and XAD fractionation. Treated wastewater showed higher SUVA value than wastewater influent, indicting less aromatic characteristic of organic matter. XAD fractionation showed hydrophilic fraction decreased though wastewater treatment, suggesting microbes preferentially digest hydrophilic and aliphatic molecules rather than hydrophobic and aromatic molecules of organic matter.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권3호
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• pp.167-172
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• 2003

Foam fractionation can be used to enrich a hydrophobic protein such as bromelain from an aerated dilute protein solution because the protein foams. On the other hand, a protein such as invertase, which is hydrophilic, is not likely to foam under similar aerated conditions. While a foam fractionation process may not be appropriate for recovering a hydrophilic protein alone, it is of interest to see how that non-foaming protein affects the foaming protein when the two are together in a mixture. The bromelain enrichment, activity and mass recovery were observed as a function of the solution pH in order to explore how invertase can affect the recovery of bromelain in a foam fractionation process.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2445-2450
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• 2011

화학공정 모사 소프트웨어인 HYSYS를 사용하여 Reformate 분리 공정을 열복합 증류탑으로 설계하였다. 열복합 증류탑 설계 방법을 자세히 하였고, 모사 결과를 일반 증류탑과 비교한 결과 제시된 열복합 증류탑 설계 방법이 간단하고 효율적이라는 것을 알 수 있었다. 같은 tray 단수하에서 열복합 증류탑은 일반 증류탑 대비 약 12.2% 에너지가 절약됨을 알 수 있었다.

• 상하수도학회지
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• 제21권5호
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• pp.513-520
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• 2007

The simulation programs used for diagnosis and design of activated sludge process require organic fractions in municipal wastewater as the input variables. However, methods for characterizing organic fractions are still under development, and are not standardized. In this study, total COD of municipal wastewater was experimentally subdivided into readily and slowly biodegradable COD as well as soluble and particulate inert COD. The COD fractionation of the three municipal wastewater for one year shows linear relationship between each COD fraction and TCOD concentration with around 100% COD balance. This result means that the COD fraction do not vary very much with time, although the actual influent concentrations vary significantly with time and day. Therefore, the experimentally subdivided COD fractions can be utilized as wastewater specific parameters for the simulation of activated sludge processes.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3774-3778
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• 2012

Reformate 분리 공정에 대한 열복합 증류탑의 가능한 제어 구조를 조사하고 그 제어 성능을 검토하기 위하여 동적 모사를 수행하였다. Aspen HYSYS를 사용하여 $3{\times}3$ 제어구조를 적용하여 여러 가지 제어구조로 동적 모사한 결과 Reformate 분리 공정 주탑의 상부, 중간, 하부 제품 조성은 각각 reflux flow rate, 주탑에서 전처리탑 상부로 흐르는 liquid draw rate, vapor boilup rate로 제어되는 구조가 가장 운전 안정성이 확보됨을 확인하였다.

• 펄프종이기술
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• 제38권3호
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• pp.72-78
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• 2006

The extraction properties of the biological waste originated from the Tobacco industry were evaluated. The biological waste have been recycled and transformed into a valuable material, so called a reconstituted tobacco sheet(Recon) by the papermaking process. In this process, The mechanical extraction process, which divides the mixed raw material slurry into the soluble stock and the insoluble stock, could affect not only the quality of final Recon product but also the productivity of whole Recon making process. This study investigated the effects of the extraction process on the slurry properties in detail. In order to quantify the amounts of the solubles which resided in the insoluble fibers, the washing treatment of the stock before and after squeezing process was applied. The amounts of the residual solubles showed little changes according to each stage of the extraction process. The fractionation of the slurry showed the difference in the amount of soluble in the stock depending on the size of the biological waste. After the extraction process, the bigger size fiber portion contained about 19%(by weight) in soluble after pressing but the smaller size fiber portion 9% in soluble. The fractionation ratio of the stocks also was changed by the screw press process, which could demonstrate the physical effects of the mechanical extraction.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권1호
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• pp.26-30
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• 2002

A droplet fractionation method was previously developed to concentrate a dilute nonfoaming protein solution. In that earlier study with invertase, it was demonstrated that droplets created by ultrasonic energy waves could be enriched up to 8 times that of the initial dilute invertase solution. In this study, a mixture of bromelain (a foaming protein) and invertase (a nonfoaming protein) is investigated as a preliminary step to determine if droplet fractionation can also be used to separate a non-foaming protein from foaming proteins. The foaming mixture containing bromelain is first removed by bubbling the binary mixture with air. After the foam is removed, the protein rich air-water interfacial layer is skimmed off (prior to droplet fractionation) so as not to interfere with the subsequent droplet production from the remaining bulk liquid, rich in non-foaming protein. Finally, sonic energy waves are then applied to this residual bulk liquid to recover droplets containing the non-foaming protein, presumed to be invertase. The primary control variable used in this droplet fractionation process is the pH, which ranged for separate experiments between 2 and 9. It was observed that the maximum overall protein partition coefficients of 5 and 4 were achieved at pH 2 and 4, respectively, for the initial foaming experiment followed by the post foaming droplet fractionation experiment.

• 한국가시화정보학회지
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• 제15권2호
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• pp.41-47
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• 2017

Microring/nanoring structure has high applicability for nano-antenna and biosensor thanks to its superior optical characteristics. Although coiling nanowires manufactured using immiscible emulsion droplets have an advantage in mass production, this process also forms nanowire bundles. In this study, we solved the nanowire bundle problem by size-selective sorting of the emulsion droplets in a pinched flow fractionation microchannel. Utilizing silver nanowires and immiscible emsulsion droplets, we investigated the correlation between the size of ring droplets and bundle droplet. We visualized the sorting process for glass particles and microring-containing emulsion droplets. Droplets were sorted based on their size, and the ratio of bundle droplets in solution decreased. This droplet-sorting strategy has potential to help the printing and coating process for manufacturing of ring structure patterns and developing of functional materials.