Editor’s Choice

Editor’s Choice

340 … NICE, 제34권 제3호, 2016

Korean Journal of Chemical Engineering, Vol.33, No.5, 1514-1529, 2016

Metal hollow sphere electrocatalysts

Abstract - Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.

Korean Journal of Chemical Engineering, Vol.33, No.5, 1530-1533, 2016

Alkaliphilic lysine decarboxylases for effective synthesis of cadaverine from L-lysine

Abstract - The enzymatic decarboxylation of L-lysine using lysine decarboxylase is a promising biological approach for producing cadaverine, a versatile platform chemical for bio-polyamides. However, due to the problem with elevated pH in the reaction solution during the enzymatic process, it is desirable to use lysine decarboxylases effectively active in alkaline conditions. In this study, the catalytic properties of three lysine decarboxylases from Selenomonas ruminantium (srLDC), Vibrio vulnificus (vvLDC), and Geobacillus thermodenitrificans (gtLDC) were characterized, and the applicability of the enzymes in alkaline conditions was investigated. Among the three enzymes, only vvLDC exhibited effective activity in alkaline pH conditions. The conversion rate of vvLDC was 1.5-fold higher than that of srLDC and 5.3-fold higher than that of gtLDC in pH 9.0. The results indicate that vvLDC is more advantageous than srLDC and gtLDC for the enzymatic conversion of L-lysine to cadaverine in alkaline conditions.

Korean Journal of Chemical Engineering, Vol.33, No.5, 1669-1673, 2016

Production of polyhydroxyalkanoates by batch and fed-batch cultivations of Bacillus megaterium from acid-treated red algae

Alkotaini B, Koo H, Kim BS

Abstract - Polyhydroxyalkanoates (PHAs) are linear polyesters synthesized by microbial fermentation of various substrates. PHAs are accumulated in microbial cells in order to store carbon and energy for future use. We used acid- pretreated red alga (Gelidium amansii) as a cheap, abundant carbon source to produce PHA via batch and fed-batch cultivation of Bacillus megaterium KCTC 2194. After acid treatment of 10% (w/v) G. amansii, 25.5 g/L galactose, 3.6 g/L glucose, 6 g/L 5-HMF, and 1.05 g/L levulinic acid were formed. In batch culture at pH 7, the dry cell weight (DCW) and PHA content increased to 5.5 g/L and 51.4%, respectively. The cell concentration was enhanced by fed-batch cultivation

NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 34, No. 3, 2016 … 341 using two feeding strategies: pH-stat and intermittent feeding. When the pH-stat feeding strategy was employed to add concentrated hydrolysate to the fermentor, DCW increased to 8.2 g/L, with 53.2% PHA content. When concentrated hydrolysate was fed using the intermittent feeding strategy, higher DCW (10.1 g/L) was obtained, along with a slight increase of PHA content to 54.5%. This study demonstrates that red algae could be used after simple acid treatment, to produce PHA without steps for enzymatic hydrolysis and inhibitor removal.

Korean Journal of Chemical Engineering, Vol.33, No.5, 1692-1697, 2016

Densities and surface tensions of binary mixtures of biodiesel, diesel, and n-butanol

Abstract - Density and surface tension have been measured for mixtures of biodiesel+n-butanol, biodiesel+diesel, and diesel+n-butanol over the entire concentration range at 283.15 K and 293.15 K and atmospheric pressure, with the combined expanded uncertainties of 1.32 kg·m-3 and 1%, receptively. Densities were determined by a single-sinker densimeter; surface tensions were measured using the surface laser light scattering method. The experimental data showed that densities and surface tensions decreased as temperature increased. The excess surface tensions and excess densities were all negative, and further fitted to the Redlich-Kister equation.

Korean Journal of Chemical Engineering, Vol.33, No.6, 1757-1766, 2016

Recent developments in scale-up of microfluidic emulsion generation via parallelization

Abstract - Microfluidics affords precise control over the flow of multiphasic fluids in micron-scale channels. By manipulating the viscous and surface tension forces present in multiphasic flows in microfluidic channels, it is possible to produce highly uniform emulsion droplets one at a time. Monodisperse droplets generated based on microfluidics are useful templates for producing uniform microcapsules and microparticles for encapsulation and delivery of active ingredients as well as living cells. Also, droplet microfluidics have been extensively exploited as a means to enable highthroughput biological screening and assays. Despite the promise droplet-based microfluidics hold for a wide range of applications, low production rate (<<10mL/hour) of emulsion droplets has been a major hindrance to widespread utilization at the industrial and commercial scale. Several reports have recently shown that one way to overcome this challenge and enable mass production of microfluidic droplets is to parallelize droplet generation, by incorporating a large number of droplet generation units (N>>100) and networks of fluid channels that distribute fluid to each of these generators onto a single chip.

To parallelize droplet generation and, at the same time, maintain high uniformity of emulsion droplets, several considerations have to be made including the design of channel geometries to ensure even distribution of fluids to each droplet generator, methods for large-scale and uniform fabrication of microchannels, device materials for mechanically robust operation to withstand high-pressure injection, and development of commercially feasible fabrication techniques for three-dimensional microfluidic devices. We highlight some of the recent advances in the mass production of highly uniform microfluidics droplets via parallelization and discuss outstanding issues.

342 … NICE, 제34권 제3호, 2016

Korean Journal of Chemical Engineering, Vol.33, No.6, 1831-1836, 2016

The particle size effect of N-doped mesoporous carbons as oxygen reduction reaction catalysts for PEMFC

The particle size effect of N-doped mesoporous carbon was investigated for ORR activity in acid condition and for issue of a mass transfer and gas diffusion in PEMFCs. As for a non-Pt ORR catalyst, nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a various particle sizes with the range of the average 20, 45 and 75 μm were synthesized by the precursor of polyaniline for the N/C species, and a mesoporous silica template was used for the physical structure for preparation of nitrogen doped OMCs. The N-doped mesoporous carbons are promoted by a transition metal (Fe) to improve catalytic activity for ORR in PEMFCs. All the prepared carbons were characterized by via scanning electron microscopy (SEM), and to evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The surface area and pore volume were increased as the particles decreased, which was effective for the mass transfer of the reactant for higher activity at the limiting current regions.

Korean Journal of Chemical Engineering, Vol.33, No.6, 1938-1941, 2016

Effects of additives on the mechanical and thermal properties of epoxy-based nanocomposites produced using sonication

Park YK, Cho CH

Abstract - Epoxy nanocomposites were synthesized in the presence of hydroxyapatite with the aid of an ultrasonicator. In general, as the amount of hydroxyapatite increased from 0wt% to 10wt%, the mechanical properties of the hydroxyapatite- containing nanocomposite were enhanced. The mechanical properties of the nanocomposite were significantly enhanced by the simple addition of 10 wt% of hydroxyapatite. Specifically, the storage modulus of the 10 wt% hydroxyapatite- containing nanocompsote was 3.2GPa, which is 46% higher compared to that of the pristine epoxy nanocomposite. The glass transition temperature of hydroxyapatite-containing nanocomposites generally decreased by few degrees in Celsius.

To investigate the effect of additives on the mechanical properties of the epoxy-based nanocomposite, nanocomposites were synthesized using both montmorillonite and tellurium dioxide instead of hydroxyapatite. Intrestingly, both additive-based nanocomposite materials resulted in an increase in the storage modulus while the glass transition temperature decreased.

These results demonstrate that the addition of few wt% of all three additives (hydroxyapatite, montmorillonite, and tellurium dioxide) can enhance the mechanical properties of epoxy-based nanocomposites.

NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 34, No. 3, 2016 … 343 Korean Chemical Engineering Research,

Vol.54, No.2, 171-174, 2016

효소연료전지의 Cathode 제조조건이 OCV에 미치는 영향

Effect of Fabrication Method of Cathode on OCV in Enzyme Fuel Cells

Abstract - 효소 전극 cathode와 PEMFC용 전극 anode를 이용하여 효소연료전지를 구동하였다. 효소 cathode는 그래파이트 분말과 효소로서 Laccase, 산화환원 매개체로서 ABTS를 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. cathode 제조조건을 변화시키며 OCV를 측정해 효소 cathode 제조 최적조건을 찾았다. 효소 cathode 압축 시 최적 압력은 4.0 bar 였다. 효소 cathode에서 그래파이트가 95%일 때 최고의 OCV를 나타냈다. cathode기질 용액의 최적 글루코스 농도는 0.4 mol/l이었다.

Korean Chemical Engineering Research, Vol.54, No.2, 223-228, 2016

미세접촉인쇄법을 이용한 지방세포 칩 제작

Simple Fabrication of Adipocyte Cell Chip Using Micropatterning

Abstract - 본 논문은 PDMS을 기반으로 한 미세접촉인쇄법을 사용하여 보다 효율적으로 지방세포를 선택적으로 배양접시에 부착시켰으며 패터닝 된 배양접시에서 지방세포가 빠르게 지방분화를 가능하게 하였다. PDMS을 이용한 선택적 표면처리 방법은 기존의 세포칩 제작과 달리 소량의 유기용매사용, 저가의 장비 사용, 또한 효율적으로 특정 지역 안에서 지방세포를 고정화하고 성장시킬 수 있으며 이를 통해 지방세포의 생리학적 상태를 손쉽게 관찰할 수 있는 분석 기술로 활용된다. 이렇게 구성된 지방세포칩 위에 대표적인 비만 억제제 약물인 Orlistat을 0.2 μM~5.0 μM 농도로 처리하였을 때 대조군에 비하여 최대 26.5%의 억제 효과가 나타남을 확인하였다. 따라서, 본 논문에서 제안하는 방법을 통하여 다양한 비만 억제제 약물 탐색을 위한 세포칩으로 활용이 가능할 것으로 기대된다.

Korean Chemical Engineering Research, Vol.54, No.2, 239-247, 2016

고정층 흡착탑에서 다성분 휘발성 유기화합물의 활성탄 흡착 특성

Activated Carbon Adsorption Characteristics of Multi-component Volatile Organic compounds in a Fixed Bed Adsorption Bed

조종훈, 이시훈, 이영우

Abstract - 본 연구에서는 상용활성탄 4가지를 사용하여 산업공정에서 사용빈도가 높은 톨루엔, isopropyl alcohol (IPA), ethyl acetate (EA), 3성분계를 대상으로 흡착특성을 고찰하였다. 고찰결과 3가지 휘발성 유기화합물 중 활성탄과 가장 친화력이 낮은 IPA의 파과점이 가장 짧았으며 다음으로 EA, 톨루엔 순으로 파과점이 길어지는 것을 알 수 있었다. 가장 파과점이 짧은 IPA를 기준으로 단일성분, 2성분, 3성분계의 파과점 변화를 고찰한 결과 성분 수가 많아질수록 파과점이 낮아지는 것을 알 수 있었으며 이는 친화력이 낮은 물질이 친화력이 높은 물질에 의해 치환되는 경쟁흡착에 의한 것을 알 수 있었다. 따라서 톨루엔-IPA-EA 3성분계 흡착에서는 IPA의 파과를 기준으로 흡착탑을 설계하여야 하며 실제 산업체에서 흡착탑을 설계하는 기준도 가장 친화력이 낮은 물질을 기준으로 하여야 함을 알 수 있었다.