[Editor’s Choice]

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548 … NICE, 제31권 제4호, 2013 Korean Journal of Chemical Engineering, Vol.30, No.7, 1347-1358, 2013

Non-vacuum deposition of CIGS absorber films for low-cost thin film solar cells Lee D, Yong K

Abstract - Thin film solar cells composed of chalcopyrite Cu(In

1-x

Gax)(Se

1-y

S

y

)

2

(CIGSSe) absorbers have gained considerable attention in recent years in an effort to develop sustainable technologies for harnessing clean energy.

Nonvacuum solution methods can reduce production costs by replacing vacuum-based deposition methods with large- scale, high-throughput processes. The efficient use of materials can reduce production costs. Non-vacuum processes generally rely on two sequential steps: solution-coating, followed by a post-annealing process. Depending on the point at which the CIGS phase evolves, non-vacuum processes can be categorized as nanoparticle (NP) approaches or molecular precursor approaches. These two types of liquid processes are believed to be compatible with a variety of applications, such as roll-to-roll coating for the production of flexible, portable devices. Additional thermal treatments using a gaseous chalcogen or oxygen can improve the absorber quality. This review describes the current status of chalcopyrite thin film solar cells fabrication methods via low-cost solution routes. An analysis of recently published reports describing liquid- based deposition methods is introduced, and the features of the development steps are compared. Finally, a discussion and future outlook are offered.

Korean Journal of Chemical Engineering, Vol.30, No.7, 1403-1409, 2013

Phase-change core/shell structured nanofibers based on eicosane/poly(vinylidene fluoride) for thermal storage applications

Do CV, Nguyen TTT, Park JS

Abstract - We fabricated eicosane/poly(vinylidene fluoride) (PVDF) core/shell nanofibers by melt coaxial electrospinning as potential heat-storage applications. Eicosane, a hydrocarbon with melting point near the human body temperature and high latent heat, was chosen as the core material. Melted eicosane and PVDF solutions were coaxially electrospun using a double spinneret, in which melted eicosane was fed at 0.090-0.210 mL/h while the feeding rate of PVDF solution was maintained constant at 1.500 mL/h. The applied voltage and working distance were maintained constant at 12 kV and 17 cm, respectively. Good core/shell structure of nanofibers was observed at core feed rates of 0.090-0.180mL/h by transmission electron microscopy. Differential scanning calorimetry and thermogravimetric analysis values indicated good thermal stability and high energy-storage capacity of the obtained nanofibers. The highest amount of eicosane encapsulated in the electrospun core/shell nanofibers reached 32.5 wt% at core feed rate 0.180 mL/h and had a latent heat of 77 J/g at melting point 39.2 ℃. These shape-stabilized core/shell composite nanofibers showed good thermoregulating properties and had sufficiently high tensile strength for potential energy-storage applications, especially in smart textiles.

Korean Journal of Chemical Engineering, Vol.30, No.7, 1448-1453, 2013

Enantioseparation of chiral ofloxacin using biomacromolecules Li W, Li Y, Fu Y, Zhang J

Abstract - Natural biomacromolecules including bovine serum albumin (BSA), calf thymus DNA (ct-DNA) and fish sperm DNA (fs-DNA) were studied as the free chiral selectors to separate R- and S-ofloxacin enantiomers from racemic ofloxacin, combined with ultrafiltration and subsequent crystallization. First, the interactions between chiral ofloxacin and biomacromolecules including BSA, ct-DNA, and fs-DNA were investigated using circular dichroism and fluorescence spectroscopy. BSA exhibited stereoselective adsorption towards R-ofloxacin at pH 9.0 with an enantioselectivity of 1.23, while ct-DNA showed enantiospecific interaction with S-enantiomer with the selectivity of 1.70 at pH 5.0. One single-stage adsorption by BSA provides an enantiomeric excess in the permeate (e.e.

p

) of 14% in S-enantiomer, and five-stage operations enhance the chiral resolution to reach the e.e.

p

value of 44%. R-enantiomer with an e.e.

p

of -26% can be obtained through one single-stage adsorption by using ct-DNA, and -85% can be reached by five-stage operations. Enantiomeric mixtures with the intial e.e. of 44% (S-) can be upgraded to 95% (S-) through subsequent crystallization. This

Editor’s Choice

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NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 31, No. 4, 2013 … 549 programmable process of adsorption and desorption using BSA or ct-DNA as chiral selectors can be successfully applied to produce the enantiomers with highly optical purity.

Korean Journal of Chemical Engineering, Vol.30, No.8, 1497-1526, 2013

Carbon capture from stationary power generation sources:

A review of the current status of the technologies Muhammad Zaman, Jay Hyung Lee

Abstract - The world will need greatly increased energy supply in the future for sustained economic growth, but the related CO

2

emissions and the resulting climate changes are becoming major concerns. CO

2

is one of the most important greenhouse gases that is said to be responsible for approximately 60% of the global warming. Along with improvement of energy efficiency and increased use of renewable energy sources, carbon capture and sequestration (CCS) is expected to play a major role in curbing the greenhouse gas emissions on a global scale. This article reviews the various options and technologies for CO

2

capture, specifically for stationary power generation sources. Many options exist for carbon dioxide capture from such sources, which vary with power plant types, and include post-combustion capture, pre-combustion capture, oxy fuel combustion capture, and chemical looping combustion capture. Various carbon dioxide separation technologies can be utilized with these options, such as chemical absorption, physical absorption, adsorption, and membrane separation. Most of these capture technologies are still at early stages of development. Recent progress and remaining challenges for the various CO

2

capture options and technologies are reviewed in terms of capacity, selectivity, stability, energy requirements, etc. Hybrid and modified systems hold huge future potentials, but significant progress is required in materials synthesis and stability, and implementations of these systems on demonstration plants are needed.

Improvements and progress made through applications of process systems engineering concepts and tools

are highlighted and current gaps in the knowledge are also mentioned. Finally, some recommendations are made for future research directions.

Korean Journal of Chemical Engineering, Vol.30, No.8, 1631-1635, 2013

Regeneration dynamics of potassium-based sediment sorbents for CO

2

capture Li-wei Wang, Yong-fa Diao, Lin-lin Wang, Xiao-fang Shi, Xiao-yan Tai

Abstract - Simulating regeneration tests of Potassium-Based sorbents that supported by Suzhou River Channel Sediment were carried out in order to obtain parameters of regeneration reaction. Potassium-based sediment sorbents have a better morphology with the surface area of 156.73 m

²

·g

^-1

, the pore volume of 357.5×10.3 cm

³

·g

^-1

and the distribution of pore diameters about 2-20 nm. As a comparison, those of hexagonal potassium-based sorbents are only 2.83 m

²

g

^-1

, 7.45×10

^-3

cm

³

g

^-1

and 1.72-5.4 nm, respectively. TGA analysis shows that the optimum final temperature of regeneration is 200 and the optimum loading is about 40%, with the best heating rate of 10 ℃·min

^-1

. By the modified Coats- Redfern integral method, the activation energy of 40% KHCO

3

sorbents is 102.43 kJ·mol

^-1

. The results obtained can be used as basic data for designing and operating CO

2

capture process.

Korean Journal of Chemical Engineering, Vol.30, No.8,1652-1658, 2013

Blends of polyurethane-polymethyl methacrylate/TiO

2

-based composites

Mohammad Zuber, Shazia Tabasum, Rizwan Hussain, Muhammad Bilal Khan, Iftikhar Hussain Bukhari

Abstract - Polyurethanes (PUs) prepolymer was prepared by the reaction of toluene-2,4-diisocyanate (TDI) and poly

caprolactone diols and the chain was further extended with 1,4-butane diol (1,4-BDO) to get final polyurethane (PU). FTIR

spectra of the monomers, PU prepolymer, chain extender and final PU confirmed the reaction progress. A series of blends

were prepared by varying the percent compositions of prepared PU, procured polymethyl methacylates (PMMA) and

titanium dioxide (TiO

2

). Pellets were formed from the prepared blends (PU-PMMA/TiO

2

) using a self-designed mechanical

tool. Scanning electron microscope (SEM) images were also taken to confirm the incorporation of the TiO

2

contents into

the prepared blends. Mechanical properties such as hardness and compressive strength were studied and discussed. The

results of the study reveal that the blended sample having 80% PU, 20% PMMA content with 2.5 g TiO

2

in 100 g mixture

of PU and PMMA is very suitable for suggesting dental materials.

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550 … NICE, 제31권 제4호, 2013 Korean Chemical Engineering Research, Vol.51, No.3, 308-312, 2013

NaOH 화학적 활성화로 제조된 하이브리드 커패시터의 전기화학적 특성 The Electrochemical Characteristics of Hybrid Capacitor Prepared by

Chemical Activation of NaOH 최

최정 정은 은, 배 배가 가영 영, 양 양정 정민 민, 이 이종 종대 대

Abstract - NaOH 화학적 활성화법을 사용하여 야자각 차로부터 고 비표면적과 미세기공이 발달된 활성탄을 제 조하였다. 활성탄 제조 공정은 탄화과정에서 활성화 약품과 야자각 차의 비율과 불활성 기체 유량과 같은 실험 변수들을 분석함으로서 수행되었다. 이와 같은 NaOH 화학적 활성화에 의한 2,481 m

²

/g의 고 비표면적과 2.32

nm의 평균 기공크기를 갖는 활성탄이 얻어졌다. 양극으로 LiMn

2

O

4

, LiCoO

2

와 음극으로 제조된 활성탄을 사용

하여 하이브리드 커패시터의 전기화학적 성능을 조사하였다. LiPF

6

, TEABF

4

의 유기 전해질을 사용한 하이브리 드 커패시터의 전기화학적 거동은 정전류 충방전, 순환 전류 전압법, 사이클과 누설전류 테스트에 의해 특성화 되었다. LiMn

2

O

4

/AC 전극을 사용한 하이브리드 커패시터가 다른 하이브리드 시스템 보다 더 좋은 충방전 성능 을 보였으며, 출력밀도 1,448 W/kg와 131 Wh/kg의 고 에너지 밀도를 전달할 수 있다.

Korean Chemical Engineering Research, Vol.51, No.3, 358-363, 2013

진공튜브 속에서 분해하는 리튬암모니아 솔루션의 열전효율 향상

Thermoelectric Efficiency Improvement in Vacuum Tubes of Decomposing Liquid Lithium-Ammonia Solutions

이

이정 정윤 윤, 김 김미 미애 애, 심 심규 규철 철, 김 김지 지범 범, 전 전준 준현 현

Abstract - 순수한 리튬-암모니아(Li-NH

3

) 솔루션의 생성은 진공 상태에서 가능하지만, 고효율 열전전력을 얻기

위한 안정적이고 신뢰성 있는 분해에 대한 문제가 아직 남아있다. 본 논문은 Li-NH

3

솔루션의 열전변환 효율을 향상시키기 위한 새로운 방법을 다루었다. 제안된 방법은 Li-NH

3

솔루션의 합성과 분해를 위해 ‘U -’ 형태의 파이 렉스 진공 튜브를 사용하였다. 튜브 상부에는 기존 ‘U’ 형태의 파이렉스 진공 튜브의 두 다리를 연결하는 기체 의 이동통로가 있는데, 이는 고온부(Hot side)에서 분해가 진행될 때 NH

3

기화에 따른 양단의 내부압력 불균형 을 방지하는 역할을 한다. 열전 실험 결과, ‘U’ 형태 튜브 속에서 솔루션 반응은 기존 ‘U’ 형태에 비해 매우 안정 적이고 효율적으로 이루어졌으며, 결과적으로 열전변환 효율이 향상됨을 보였다. 또한, 제안 방식은 장시간에 걸친 고효율 열전 발전을 위해 튜브 속에서 합성과 분해가 순환되는 가역반응을 제공함이 입증되었다.

Korean Chemical Engineering Research, Vol.51, No.3, 388-393, 2013

Graphene의 플라즈마 표면 개질과 박테리아 셀룰로오스와의 결합성 검토 Plasma Surface Modification of Graphene and Combination with Bacteria Cellulose

임

임은 은채 채, 김 김성 성준 준, 오 오일 일권 권, 기 기창 창두 두

Abstract - 본 연구에서는 물리적 강도가 강한 천연 고분자인 박테리아 셀룰로오스(BC)를 기반으로 전기적 성질

이 매우 뛰어난 그래핀을 결합시켜 터치 스크린과 같은 투명 전도성 필름을 제조할 수 있는 가능성을 확인하고

자 한다. 그래핀을 BC와 결합하기 위해서 라디오파의 인가강도와 처리시간을 달리하여 상온에서 산소 플라즈

마 처리를 통해 표면을 개질시켰다. 개질된 그래핀의 물에 대한 접촉각이 130° 에서 12° 로 매우 작아진 것으로

친수성이 향상되었다. 또한, XPS 분석에서는 graphene 처리 전 산소함유량 2.99%에서 10.98%로 크게 증가하였

다. 그래핀의 손상은 Raman 분석에서 I

D

/I

G

비로 정도를 알 수 있다. 처리 전 I

D

/I

G

비가 0.11로 손상 정도가 가장

낮았고, 처리 후 0.36~0.43으로 처리 전에 비해 그래핀의 구조적 결함이 증가하였다. 용해시킨 BC에 그래핀을

0~0.04 wt% 첨가하여 제조한 막의 XRD 분석에 의하면 BC막과 plasma 처리된 graphene이 함유된 결합막이 동일

한 2θ 로서 화학적으로 잘 결합되었음을 확인하였다. 이는 SEM 이미지에서 BC와 그래핀의 결합 상태를 확인한

것과 일치하였다. FT-IR 분석에서 플라즈마 처리한 그래핀이 함유된 결합막의 1,000~1,300 cm

^-1