• Korean Chemical Engineering Research
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• 제53권2호
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• pp.216-223
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• 2015

The present work explores the potential of wet air oxidation (WAO) for pretreatment of mixed lignocellulosic biomass to enhance enzymatic convertibility. Rice husk and wheat straw mixture (1:1 mass ratio) was used as a model mixed lignocellulosic biomass. Post-WAO treatment, cellulose recovery in the solid fraction was in the range of 86% to 99%, accompanied by a significant increase in enzymatic hydrolysis of cellulose present in the solid fraction. The highest enzymatic conversion efficiency, 63% (by weight), was achieved for the mixed biomass pretreated at $195^{\circ}C$, 5 bar, 10 minutes compared to only 19% in the untreated biomass. The pretreatment under the aforesaid condition also facilitated 52% lignin removal and 67% hemicellulose solubilization. A statistical design of experiments on WAO process conditions was conducted to understand the effect of process parameters on pretreatment, and the predicted responses were found to be in close agreement with the experimental data. Enzymatic hydrolysis experiments with WAO liquid fraction as diluent showed favorable results with sugar enhancement up to $10.4gL^{-1}$.

• 산업기술연구
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• 제39권1호
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• pp.7-14
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• 2019

Carbon nanotubes (CNT) on metal substrates are definitely beneficial because they can maintain robust mechanical stability and high conductivity between CNT and metal interfaces. Here, we report direct growth of CNT on Ni-based superalloy, Inconel 600, using thermal chemical vapor deposition (CVD) with acetylene feedstock in the growth temperature range of $400-725^{\circ}C$. Furthermore, we studied the effect of substrate pretreatment on the growth yield enhancement and growth temperature decrease of CNT on Inconel 600. Activation energy (AE) for CNT growth was estimated from the CNT height change with respect to the growth temperature. The AE values significantly decreased from 205.03 to 24.35 kJ/mol by the pretreatment of thermal oxidation of Inconel substrate at $725^{\circ}C$ under ambient. Higher oxidation temperature tends to have lower activation energy. The results have shown the importance of pretreatment temperature on CNT growth yield and growth temperature decrease.

• Carbon letters
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• 제17권1호
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• pp.1-10
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• 2016

Lignocellulosic biomass conversion to biofuels such as ethanol and other value-added bio-products including activated carbons has attracted much attention. The development of an efficient, cost-effective, and eco-friendly pretreatment process is a major challenge in lignocellulosic biomass to biofuel conversion. Although several modern pretreatment technologies have been introduced, few promising technologies have been reported. Microwave irradiation or microwave-assisted methods (physical and chemical) for pretreatment (disintegration) of biomass have been gaining popularity over the last few years owing to their high heating efficiency, lower energy requirements, and easy operation. Acid and alkali pretreatments assisted by microwave heating meanwhile have been widely used for different types of lignocellulosic biomass conversion. Additional advantages of microwave-based pretreatments include faster treatment time, selective processing, instantaneous control, and acceleration of the reaction rate. The present review provides insights into the current research and advantages of using microwave-assisted pretreatment technologies for the conversion of lignocellulosic biomass to fermentable sugars in the process of cellulosic ethanol production.

• Membrane and Water Treatment
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• 제5권1호
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• pp.15-29
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• 2014

Reverse Osmosis (RO) desalination has gained wide and increasing acceptance around the world as a straightforward undertaking to alleviate the alarming water crisis. An enhanced monitoring of the quality of the water feeding in seawater RO (SWRO) plant through the application of an effective pretreatment option is one of the keys to the success of RO technology in desalination plants. Over the past 10 years, advances in ultrafiltration (UF) membrane technologies in application for water and wastewater treatment have prompted an impetus for using membrane pretreatment in seawater desalination plants. By integrating SWRO plant with UF pretreatment, the rate of membrane fouling can be significantly reduced and thus extend the life of RO membrane. With the growing importance and significant advances attained in UF pretreatment, this review presents an overview of UF pretreatment in SWRO plants. The advantages offered by UF as an alternative of pretreatment option are compared to the existing conventionally used technologies. The current progress made in the integration of SWRO with UF pretreatment is also highlighted. Finally, the recent advances pursued in UF technology is reviewed in order to provide an insight and hence path the way for the future development of this technology.

• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.161-166
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• 2009

Certain microalgae have been known to use light and various carbon sources to produce carbohydrates, mainly in the form of starch. This is one of the pertinent feedstocks replacing agricultural products for the production of bioethanol by yeast. This study focuses upon dilute acid hydrothermal pretreatments at low cost and high efficiency to compete with current methods, and employs Chlamydomonas reinhardtii UTEX 90 as the feedstock. With dry cells of 5%(w/v), the algal biomass was pretreated with sulfuric acid(1-5%) under temperatures from 100 to $120^{\circ}C$, from 15 to 120 min. As a result, the glucose release from the biomass was maximum at 58%(w/w) after pretreatment with 3% sulfuric acid at $110^{\circ}C$ for 30 min. This method enabled not only starch, but also the hydrolysis of other oligosaccharides in the algal cell in high efficiency. Arrhenius-type of model equation enabled extrapolation of some yields of glucose beyond this range. The pretreated slurry was fermented by yeast, Saccharomyces cerevisiae S288C, resulting in an ethanol yield of 29.2% from algal biomass. This study suggests that the pretreated algal biomass is a suitable feedstock for ethanol production and can have a positive impact on large-scale applied systems.

• 상하수도학회지
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• 제25권4호
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• pp.565-572
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• 2011

The effects of chemical pretreatments on the excess sludge production in the membrane-coupled bioreactor were investigated. In addition, their effects on membrane fouling were also evaluated. Two membrane bioreactors were operated. In one reactor, a part of the mixed liquor was t reated with NaOH and ozone gas consecutively and was returned to the reactor. T he f lowrate of the chemical pretreatment stream was 1.5% of the influent flowrate. During the 200days of operation, the MLSS level in the bioreactor with mixed liquor pretreatment was maintained relatively constant at the range of 8,000 ~ 10,000$mg/{\ell}$ while it increased steadily up to 26,000 $mg/{\ell}$ in the absence of the pretreatment. Each reactor was equipped with two laboratory membrane modules where the flux for each module was 20, and 30 ${\ell}/m^2{\cdot}h$, respectively. With pretreatment, almost constant transmembrane pressure(TMP) was observed throughout the operation at the flux of 20 ${\ell}/m^2{\cdot}h$. Without pretreatment the membrane module at the same flux could also be operated at relatively stable condition. However, as the MLSS increases up to 25,000 $mg/{\ell}$, a fast TMP increase was observed. In conclusion, a complete control of excess sludge production in the membrane-coupled bioreactor was possible without significant deterioration of the treated water quality. In addition, it was shown that stable operation in terms of TMP is possible with sludge pretreatment and recirculation.

• KSBB Journal
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• 제29권1호
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• pp.22-28
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• 2014

In this study, we investigate the effect of pretreatment method on lipid extraction from Enteromorpha intestinalis using physical, thermo-chemical, and enzymatic process such as ultrasonication, high temperature treatment, freezing, microwave irradiation, osmotic shock, pH shock, homogenizing, and enzymatic treatment. In pretreatment with separated lipid extraction, the high extraction yield was obtained by high temperature treatment ($121^{\circ}C$ for 5 min) with 0.1 N HCl, which is 1.4 times higher than that of control. In pretreatment with direct lipid extraction, the high extraction yields were obtained by 0.1 N HCl pretreatment, microwave irradiation (700W, 1 min with twice), and 10% NaCl pretreatment, which is 1.45 times higher than that of control. In the result of enzymatic pretreatment with 17 kinds of enzymes, Cellic CTec II showed the high extraction yield of 5.3%, and which is 1.9 times higher than that of control. Moreover, the extraction yield was increased by the increase of enzyme amounts. In 10% enzyme amount, about 5.8% yield was obtained.

• KSBB Journal
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• 제7권1호
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• pp.73-78
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• 1992

곰팡이의 일종인Poria cocos, Trichodermareesei, Candide tropicalis, Aspergillus niger를 이용하여 호주산 갈탄의 액화를 연구하였다. 갈탄을 전처리하는 방법을 달리하여 전처리가 갈탄의 액화에 미치는 영향에 관하여 알아보았으며, 질산과 과산화수소가 호주산 갈탄을 액화하는데 우수한 전처리제라는 사실을 확인하였다. 사용한 여러 균주 가운데 Poria cocos가 가장 뛰어난 액화능을 나타내었으며, 석탄 액화 물질의 구조를 Infrared, Nuclear magnetic resonance, Ultraviolet 분광법을 사용하여 예측하였다.

• 한국표면공학회지
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• 제50권6호
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• pp.439-446
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• 2017

Plasma electrolyte oxidation (PEO) is a kind of anodization, in which a very high voltage or current is applied to a metal substrate in various electrolytes, allowing distinctly thick thickness of the oxide film with outstanding film properties, such as a good corrosion resistance, mechanical strength, thermal stability, and excellent adhesion to a substrate. Herein, we tried to find the optimal pretreatment conditions among commercially available solutions in order to produce PEO anodizing at relatively low voltage. We characterized the surface morphologies of the sample by scanning electron microscope (SEM), atomic force microscopy (AFM), and investigated color parameters of the pretreated surface of Ti by spectrophotometer.

• Korean Chemical Engineering Research
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• 제56권4호
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• pp.453-460
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• 2018

원유 가격의 상승과 지구온난화로 인하여 재생 가능한 바이오매스를 이용하여 산업적으로 중요한 화합물을 생산하는 연구가 주목받고 있다. 특히, 3세대 바이오매스인 해조류는 비식량 자원, 높은 생산 수율, 온실가스 저감 등 장점을 가지고 있기에 연구 되어야 할 필요가 있다. 본 연구에서는 고체분석 방법을 이용하여 4종의 해조류 중에 미역이 가장 많은 당류를 함유하는 것을 확인하였다. 미역의 효과적인 전처리를 위해 반응표면분석법을 이용하였으며 이를 통해 고체의 부하 및 촉매의 농도 증가가 총 당의 추출률과 관계 있음을 확인하였다. 4종의 락토바실러스 균주에서 미역의 전처리물을 이용하여 젖산 생산 수행하였으며 L. alimentarius와 L. brevis가 해조류 이용한 젖산생산에 적합한 균주임을 확인하였다.