Editor’s Choice

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Editor’s Choice

NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 35, No. 6, 2017 … 751 Korean Journal of Chemical Engineering,

Vol.34, No.11, 2787-2805, 2017

Sources and impacts of pharmaceutical components in wastewater and its treatment process: A review

Pavithra KG, Kumar PS, Rajan PS, Saravanan A, Naushad M

Abstract - Pharmaceutical compounds and their derivatives are major pollutants in the environment, as their metabolites affect the terrestrial as well as aquatic organisms in one or another way. In recent times, many papers have discussed the treatment procedures for single pharmaceutical and mixture of pharmaceutical components, but only few papers have discussed the fate and the exposure of pharmaceutical contaminants in our environment. In this paper, we discuss the sources and the forms of pharmaceutical products and their resultant in the environment and their addition to the microbial and to human communities. A detailed discussion of various treatment techniques from conventional to current techniques, their advantages and disadvantages is given here. Researchers are finding the techniques in order to completely degrade the contaminants and their transformed products from the environment. Among the technique, s nanotechnology was found to be an efficient technique, and the combination of nanotechnology with other conventional technologies gives higher removal efficiency.

Korean Journal of Chemical Engineering, Vol.34, No.11, 2840-2851, 2017

Statistical optimization for lithium silicate catalyzed production of biodiesel from waste cooking oil

Cherikkallinmel SK, Sugunan S, Narayanan BN, Faisal PA, Benjamin S

Abstract - Lithium silicate is one of the suitable heterogeneous catalysts for biodiesel production. The possibilities of large number of combinations of different reaction parameters make the optimization of biodiesel production process over various heterogeneous catalysts highly tedious, necessitating the development of alternate strategies for parameter optimization. Here, Box-Behnken design (BBD) coupled with response surface methodology (RSM) is employed to optimize the process parameters required for the production of biodiesel from waste cooking oil using lithium silicate as catalyst. Simple method of impregnation was performed for the material preparation and the catalyst was analyzed using different techniques. It was found that the activity is directly proportional to the basicity data obtained from temperature programmed desorption (TPD) of CO2 over various catalyst systems. The material exhibits macroporous morphology and the major crystalline phase of the most active catalyst was found to be Li2SiO3. The effects of different reaction parameters were studied and a biodiesel yield of 100% was obtained under the predicted optimum reaction conditions of methanol : oil molar ratio 15 : 1, catalyst amount 7 wt%, reaction temperature 55 °C and reaction time 2.5 h. The validation experiments showed a correlation coefficient of 0.95 between the predicted and experimental yield of biodiesel, which indicates the high significance of the model. The fuel properties of biodiesel obtained under the optimum conditions met the specifications as mentioned in ASTM D6751 and EN 14214 standards. Catalyst heterogeneity and low reaction temperature are the major attractions of the present biodiesel preparation strategy.

Highly sensitive glucose biosensor using new glucose oxidase based biocatalyst

Christwardana M, Ji JY, Chung YJ, Kwon YC

Abstract - Glucose, which is a primary energy source of living organisms, can induce diabetes or hypoglycemia if its concentration in blood is irregular. It is therefore important to develop glucose biosensor that reads the concentration of glucose in blood precisely. In the present work, we suggest new glucose oxidase (GOx) based catalysts that can improve the

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752 … NICE, 제35권 제6호, 2017

sensitivity of the glucose biosensor and make glucose measurements over a wide concentration ranges possible. For synthesizing such catalysts, a composite including pyrenecarboxaldehyde (PCA) and GOx is attached to substrate including carbon nanotube (CNT) and polyethyleneimine (PEI) (CNT/PEI/[PCA/GOx]). Catalytic activity and stability of the catalyst are then evaluated. According to the investigation, the catalyst shows excellent glucose sensitivity of 47.83 μAcm-2mM-1, low Michaelis-Menten constant of 2.2mM, and wide glucose concentration detection, while it has good glucose selectivity against inhibitors, such as uric acid and ascorbic acid. Also, its activity is maintained to 95.7% of its initial value even after four weeks, confirming the catalyst is stable enough. The excellence of the catalyst is attributed to hydrophobic interaction, C=N bonds, and π-hydrogen interaction among GOx, PCA and PEI/ CNT. The bindings play a role in facilitating electron transport between GOx and electrode.

CO and CO

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methanation over Ni catalysts supported on alumina with different crystalline phases

Le TA, Kim TW, Lee SH, Park ED

Abstract - The effect of alumina crystalline phases on CO and CO2 methanation was investigated using alumina-supported Ni catalysts. Various crystalline phases, such as α-Al2O3, θ-Al2O3, δ-Al2O3, η-Al2O3, γ-Al2O3, and κ-Al2O3, were utilized to prepare alumina-supported Ni catalysts via wet impregnation. N2 physisorption, H2 chemisorption, temperature- programmed reduction with H2, CO2 chemisorption, temperature-programmed desorption of CO2, and X-ray diffraction were employed CO2 methanation at low temperatures. CO methanation catalytic activity appeared to be related to the number of Ni surface-active sites, as determined by H2-chemisorption. During CO2 methanation, Ni dispersion and the CO2

adsorption site were found to influence catalytic activity. Selective CO methanation in the presence of excess CO2 was performed over Ni/γ-Al2O3 and Ni/δ-Al2O3; these substrates proved more active for CO methanation than for CO2

methanation.

Expanding depletion region via doping: Zn-doped Cu

2

O buffer layer in Cu

2

O photocathodes for photoelectrochemical water splitting

Lee KH, Lee CH, Cheong JU, Lee SK, Kim ID, Joh HI, Lee DC

Abstract - We report photoelectrochemical hydrogen evolution reaction using a Cu2O-based photocathode with a layer doped with Zn ions. The doping results in the shift of the onset flat-band potential of the photocathode, likely a consequence of maximized band-bending in the Cu2O/Zn : Cu2O heterojunction. Systematic electrochemical analysis reveals that expansion of depletion region is responsible for the enhanced photoelectrochemical performance, e.g., the increase of photocurrent and reduced internal resistance.

Korean Chemical Engineering Research, Vol.55, No.5, 660-667, 2017

등온 미세열량계를 이용한 n-Hexane-알칸계 이성분 혼합물 및 NaOH/Water/Ethanol계의 과잉 엔탈피 측정 및 계산

Measurement and Calculation of Excess Enthalpies for n-Hexane/Alkane series and NaOH/Water/

Ethanol System using Isothermal Microcalorimeter

최인규, 유성식

Abstract - 화학공정에서 증류 또는 추출 등 분리 장치의 설계 및 조업에 있어서 혼합물의 평형데이터는 필수적이다.

이들 평형데이터는 실험을 통해서 얻거나 알려진 이성분 매개변수를 이용하여 모델에 의한 계산으로 얻을 수 있다.

일반적으로 이들 매개변수를 구하기 위해서 기-액, 액-액 등의 상평형 실험 데이터를 주로 이용하지만, 본 연구에서는

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NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 35, No. 6, 2017 … 753 보다 간편한 방법으로서 흐름형 미세열량계를 이용하여 혼합물의 과잉엔탈피 실험데이터를 얻고, 이 데이터를 이용하여 여러 이론들의 매개변수를 구하고자 하였다. 더불어, 알칸계의 경우 탄소의 사슬길이와 엔탈피 그리고 이성분 매개변수간의 관계를 알아보고자 하였으므로 n-hexane + alkane (n-pentane, n-heptane, n-octane, n-dodecane)계들에 대해서 298.15 K에서 과잉엔탈피를 측정하였으며, 이 실험데이터로부터 Wilson, NRTL, UNIQUAC의 매개변수를 구하였다. 또한, 다양한 분야에 적용 가능한 전해질 계의 상호작용 및 회합현상에 대한 기본정보를 과잉엔탈피 실험 데이터들과 기존 이론을 이용하여 얻고자 하였다. 우선은 기초적인 실험으로서 NaOH/Water/Ethanol 계에 대한 과잉 엔탈피를 측정하고, electrolyte- NRTL (eNRTL) 이론을 이용하여 응용성을 검토하고자 하였다.

SIS-SBS 개질아스팔트 방수시트재 물성 최적화

Optimization to Prepare SIS-SBS Modified Asphalt for Waterproof-sheet

임광희

Abstract - 본 연구에서는 방수시트재를 위한 아스팔트의 styrene-butadiene-styrene (SBS)와 styrene-isoprene-styrene (S I S)에 의한 개질에 있어서 자가치유성을 가지는 개질아스팔트 방수시트재의 연화점(s o f t e n i n g p o i n t), 침입도(penetration), 저온굴곡저항성능(low temperature flexibility), 점도(viscosity) 및 부착성능(adhesion) 등의 물성을 관찰하고, 반응표면분석법(response surface methodology, RSM)을 활용하여 아스팔트 질량 대비 SBS와 SIS의 적정조성을 도출하고 자가치유성을 가지는 개질아스팔트 방수시트재의 물성을 최적화하였다. 고온에서 측정이 수행되는 연화점과 점도는 SBS 또는 SIS의 함량이 증가함에 따라서 유의하게 값이 증가하였다. 그러나 함량 대비 연화점과 점도 증가분은 SBS 경우가 SIS보다 커짐이 관찰되었다. 이러한 원인은 SBS와 SIS의 열적거동의 차이 때문인데, SBS는 고온에서 점도 상승을 동반하는 겔화(gelation)가 되어 가교도가 커지나 SIS는 점도감소를 초래하는 폴리이소프렌 블록의 사슬분리(chain scission)때문에 사슬꼬임(chain entanglement)이 상대적으로 적어지기 때문이다. 반면에 SIS-SBS 개질아스팔트는 상온에서 측정되는 침입도, 부착성능 및 저온굴곡성능에 대하여, 아스팔트 63 g을 기본으로 SIS 4~5 g과 SBS 8.5 g의 조성에서 최소 탄성거동을 나타내어 최대 침입도 및 최대 부착성능과 최저 저온굴곡성능 값을 보였다.

수소불화탄소 및 수소염화불화탄소 냉매(R-134a, R-227ea, R-236fa, R-141b)를 이용한 가스 하이드레이트 형성에 관한 계산화학적 해석

Computational Chemistry Study on Gas Hydrate Formation Using HFC & HCFC Refrigerants (R-134a, R-227ea, R-236fa, R-141b)

김경민, 안혜영, 임준혁, 이제근, 원용선

Abstract - 가스 하이드레이트 형성원리를 이용한 해수담수화는 이미 상용화된 역삼투 방식에 비하여 아직 실증화 단계이지만 그 공정이 비교적 단순하고 특히 냉매를 객체가스로 사용할 경우 아주 낮은 공정 온도가 필요하지 않아 에너지 소비량(thermal budget)이 향상될 가능성이 있기 때문에 여전히 많은 관심을 받고 있다. 따라서 본 연구에서는 수소불화탄소(HFC, hydrofluorocarbon) 및 수소염화불화탄소(HCFC, hydrochlorofluorocarbon) 계열의 냉매들을 객체가스로 한 가스 하이드레이트형성 거동을 에너지적인 관점에서 해석하고자 하였고 이를 위해 밀도 범함수(DFT, density functional method) 이론을 기반으로 한 분자모델링을 도입하였다. 객체가스(guest gas)로 R-134a, R-227ea, R-236fa, R-141b를 선정하였으며 계산을 위하여 물 분자로 이루어진 512, 51262, 51264의 세 가지 구조의 동공들(cavities)을 구성하였다. 동공, 객체가스, 그리고 객체가스가 삽입된 동공의 구조를 분자모델링을 이용하여 각각 최적화하였고 계산된 각 구조의 에너지로부터 동공과 객체가스의 결합에너지(binding energy)를 계산하였다. 마지막으로 결합에너지를 비교함으로써 어느 냉매가 가장 유리한 조건에서 가스 하이드레이트를 형성할 지를 판단하였다.

결과적으로 R-236fa가 가장 자발적(spontaneous)으로 가스 하이드레이트를 형성 할 것으로 예상되었고 사람에 대한 낮은 독성과 물에 대한 작은 용해도 측면에서도 가장 적절한 선택으로 평가되었다.