Editor’s Choice

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Editor’s Choice

122 … NICE, 제35권 제1호, 2017

Korean Journal of Chemical Engineering, Vol.34, No.1, 41-53, 2017

Structural evolution of hierarchical porous NiO/Al

2

O

3

composites and their application for removal of dyes by adsorption

Rong J, Zhang T, Qiu F, Chen M

Abstract - Hierarchical porous NiO/Al2O3 composites were successfully prepared by two-steps. First, the core-shell structured Al2O3 microspheres were prepared via a template-free hydrothermal route using KAl(SO4)2·12H2O and Al2(SO4)3·18H2O as aluminum source. Then, the NiO/Al2O3 composites with micro- and nano-hierarchical structures were prepared by a hydrothermal method combining the subsequent calcination process. The obtained characterization result presented that the morphology of hierarchical Al2O3 microsphere tuned to irregular platelets by simply varying Ni/Al ratios.

The BET analysis showed that the special surface area from 52.12m² g^-1 to 214.8m² g^-1 after two hydrothermal complex process. Effects of Ni/Al ratio, adsorbent dosage, Congo red (CR) concentration, coexisting ions, adsorption time and temperature were investigated. The obtained results indicated that NiO/Al2O3 composite had the high adsorption efficiency (99.6%) and great adsorption capacity (186.9mg g-1) under the optimum conditions. The adsorption isotherm and kinetics data were found to be well fitted and in good agreement with the Langmuir isotherm model and pseudo-second order model, respectively. The hierarchical porous NiO/Al2O3 composites presented remarkably higher adsorption efficiency during five recycling, which showed their potential as the highly efficient adsorbent for removal of CR in wastewater.

Harvesting of Scenedesmus obliquus cultivated in seawater using electro-flotation

Shin H, Kim K, Jung JY, Bai SC, Chang YK, Han JI

Seawater, when supplemented to a growth medium, appears to stimulate auto-flocculation of a certain microalgae species like Scenedesmus obliquus and thus renders its harvesting easy. To make use of this unique response for the purpose of biomass harvesting, S. obliquus was grown in a seawater-added medium and then collected in electrochemically-mediated ways. Significantly higher harvesting efficiency and energy saving were observed with electroflotation (EF) than with electro-coagulation-flotation (ECF) and the standard BG11 medium. An optimal EF condition, the highest recovery rate with least energy use, was found with a supply of 0.5 A. Seawater amendment was most beneficial in a level of 10%. All this clearly showed that applying EF to cells cultivated in the seawater-supplemented medium is a promising harvesting means that enables one to obtain algae biomass without interfering with the downstream process of biodiesel production.

Skin permeability of compounds loaded within dissolving microneedles dependent on composition of sodium hyaluronate and carboxymethyl cellulose

Park Y, Kim B

Abstract - Dissolving microneedles are transdermal delivery systems designed to mechanically penetrate the skin and fully dissolve in the skin in a minimally invasive manner. In this study, the skin permeability of compounds encapsulated in microneedles was controlled by changing the composition of microneedle materials. Sodium hyaluronate (SH) and carboxymethyl cellulose (CMC) were chosen as structural materials and amylopectin was used to increase the mechanical strength of microneedles. To determine the effect of microneedle composition on skin permeability, microneedle properties such as mechanical strength and solubility were investigated according to various compositions of SH and CMC. When the CMC fraction in the needle increased, the mechanical strength of the microneedle increased, leading to high skin permeability of rhodamine B, a model compound. Using microneedles, significantly higher skin permeability of niacinamide was also obtained.

These results indicate that the microneedles developed in this study improved the skin permeability of compounds loaded in the needle, and the skin permeability could be tuned by changing the composition of microneedle materials.

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NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 35, No. 1, 2017 … 123 Korean Journal of Chemical Engineering,

Vol.34, No.2, 320-337, 2017

Effect of surface composition of Fe catalyst on the activity for the production of high-calorie synthetic natural gas (SNG)

Lee YH, Lee KY

Abstract - An Fe2O3 catalyst was applied to the production of high-calorie synthetic natural gas (SNG). With this catalyst, the product distribution changed as the surface composition of the Fe2O3 catalyst changed. The effect of these changes on the catalytic activity was investigated. The active phases of the Fe2O3 catalyst were a mixture of low-carbon FeCx and Fe3C, which was maintained for 10 h, accompanied by the regeneration of Fe3O4. The surface Fe concentration increased after 10 h reaction, and this increased the CO conversion. In addition, the amounts of adsorbed C2H4 and C3H6 increased, which resulted in an increase in carbon chain growth. The surface concentration of oxygen also increased due to the regeneration of Fe3O4, thus reducing the C3H6 adsorption strength; in contrast, C2H4 adsorption increased, resulting in an enhanced paraffin-to-olefin (p/o) ratio for C2 hydrocarbons and reduced p/o ratio for C3 hydrocarbons.

High speed spin coating in fabrication of Pebax 1657 based mixed matrix membrane filled with ultra-porous ZIF-8 particles for CO

₂

/CH

₄

separation

Jomekian A, Behbahani RM, Mohammadi T, Kargari A

Abstract - Modified ultra-porous ZIF-8 particles were used to prepare novel ZIF-8/Pebax 1657 mixed matrix membranes (MMMs) on PES support for separation of CO2 from CH4 using spin coating method. TEM and SEM were used to characterize modified ZIF-8 particles. SEM was also used to investigate the morphology of synthesized MMMs. The MMMs with thinner selective layer showed higher CO2 permeability and lower CO2/CH4 selectivity in permeation tests compared to MMMs with thicker selective layer. The plasticization was recognized as the main reason for rise in CO2

permeability and drop in CO2/CH4 selectivity of thinner MMMs. The gas sorption results showed that the high permeability of CO2 in MMMs is mainly due to the high solubility of this gas in MMMs, leading to high CO2/CH4 solubility selectivity for MMMs. The fractional free volume and void volume fraction of MMMs increased as the thickness of membrane decreased. Applying higher mixed feed pressures and permeation tests temperatures resulted in increase in CO2

permeability and decrease in CO2/CH4 selectivity. At highest testing temperature (60 oC), the CO2 permeability of synthesized MMMs with thinner selective layer remarkably increased.

Study of UV aging on the performance characteristics of vegetable oil and palm oil derived isocyanate based polyurethane

Das S, Pandey P, Mohanty S, Nayak SK

Abstract - The impact of UV aging on the characteristic properties of synthesized polyurethane (PUs) from castor oil and transesterified castor oil with palm oil based isocyanate and 1,4 butanediol was investigated at different exposure time of 0, 250, 500, 750 and 1,000 h, respectively. The aging properties of the PU films were analyzed through differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Tensile tests. The PU films derived from castor oil showed noticeable changes in chemical structure after 250 h of UV exposure owing to chain scission of the urethane group. A considerable decrease in the thermal and tensile properties of the developed PU films was observed due to the plasticization phenomenon. SEM micrographs revealed morphological changes through the appearance of cracks and blisters composed of primary amines on the surface of exposed PU films. However, PUs derived from transesterified castor oil with a higher hydroxyl value exhibited improved UV resistance characteristics due to higher crosslinking and degrade only after 750 h of exposure. Thus, the synthesized green PUs based on transesterified castor oil with palm oil based isocyanate compositions can be candidate materials for developing UV resistant coating material.

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124 … NICE, 제35권 제1호, 2017

Korean Chemical Engineering Research, Vol.54, No.6, 723-733, 2016

구리 전해 도금을 이용한 실리콘 관통 비아 채움 공정

Through-Silicon-Via Filling Process Using Cu Electrodeposition

김회철, 김재정

Abstract - 반도체 배선 미세화에 의한 한계를 극복하기 위해 실리콘 관통 비아(through silicon via, TSV)를 사용한 소자의 3차원 적층에 대한 연구가 진행되고 있다. TSV 내부는 전해도금을 통해 구리로 채우며, 소자의 신뢰성을 확보하기 위해 결함 없는 TSV의 채움이 요구된다. TSV 입구와 벽면에서는 구리 전착을 억제하고, TSV 바닥에서 선택적으로 구리전착을 유도하는 바닥 차오름을 통해 무결함 채움이 가능하다. 전해 도금액에 포함되는 유기 첨가제는 TSV 위치에 따라 국부적으로 구리 전착 속도를 결정하여 무결함 채움을 가능하게 한다. TSV의 채움 메커니즘은 첨가제의 거동에 기반하여 규명되므로 첨가제의 특성을 이해하는 연구가 선행되어야 한다. 본 총설에서는 첨가제의 작용기작을 바탕으로 하는 다양한 채움 메커니즘, TSV 채움 효율을 개선하기 위한 평탄제의 개발과 3-첨가제 시스템에서의 연구, 첨가제 작용기와 도금 방법의 수정을 통한 채움 특성의 향상에 관한 연구를 소개한다.

Review on the Determination of Frumkin, Langmuir, and Temkin Adsorption Isotherms at Electrode/

Solution Interfaces Using the Phase-Shift Method and Correlation Constants

Chun J, Chun JH

Abstract - This review article described the electrochemical Frumkin, Langmuir, and Temkin adsorption isotherms of over- potentially deposited hydrogen (OPD H) and deuterium (OPD D) for the cathodic H2 and D2 evolution reactions (HER, DER) at Pt, Ir, Pt-Ir alloy, Pd, Au, and Re/normal (H2O) and heavy water (D2O) solution interfaces. The Frumkin, Langmuir, and Temkin adsorption isotherms of intermediates (OPD H, OPD D, etc.) for sequential reactions (HER, DER, etc.) at electrode/

solution interfaces are determined using the phase-shift method and correlation constants, which have been suggested and developed by Chun et al. The basic procedure of the phase-shift method, the Frumkin, Langmuir, and Temkin adsorption isotherms of OPD H and OPD D and related electrode kinetic and thermodynamic parameters, i.e., the fractional surface coverage (0 ≤ θ ≤ 1) vs. potential (E) behavior (θ vs. E), equilibrium constant (K), interaction parameter (g), standard Gibbs energy (ΔGθ°) of adsorption, and rate (r) of change of ΔGθ° with θ (0 ≤ θ ≤ 1), at the interfaces are briefly interpreted and summarized. The phase-shift method and correlation constants are useful and effective techniques to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and related electrode kinetic and thermodynamic parameters (θ vs. E, K, g, ΔGθ°, r) at electrode/solution interfaces.

전산유체역학을 이용한 PEMFC의 성능에 대한 3차원 유로 구조의 영향

Effects of 3D Flow-Channel Configurations on the Performance of PEMFC using Computational Fluid Dynamics

한경호, 윤도영

Abstract - 본 연구에서는 3차원 전산유체역학 모델을 적용하여 서펜타인 유로를 갖는 고분자 전해질 분리막(PEM) 연료전지의 성능평가를 수행하였다. PEM 연료전지의 전산 모델은 등온조건하에서의 이동현상을 고려하여, 물질 및 운동량 전달, 전극에서의 반응속도론 그리고 전기적 흐름을 모두 포함하였다. 한편, 병류로 흐르도록 형성된 구조의 유로 형태는 본 연료전지모델에서 유로의 폭과 높이의 비인 종횡비와 유로와 립 폭의 비인 반응면적비를 변화시키며 다양한 형상으로 고려되었다. 유로의 형상이 변화될 경우 연료전지 내부의 수소와 산소의 질량분율 분포가 계산되었으며, 이에 따라, 활성화과전압의 계산 값이 변하게 되며 전류밀도 분포가 최종적으로 결정되었다. CFD 결과는 종횡비가 클수록 성능이 증가하고 반응면적비가 클수록 성능이 감소하는 것을 보였다. 본 연구의 모델에 의하면 서펜타인 유로의 형상에 의해, 성능특성이 경향성을 보이는 결과를 보여주었으며, 이와같은 결과는 다른 문헌에 보고 된 CFD 결과들과 전반적으로 잘 부합하는 것으로 나타났다.