Performance of electrospun nanofibrous membranes for trapping of BTX aromatic hydrocarbons and heavy metal ions: Mechanisms, isotherms and kinetics

Ge, Jun Cong,Choi, Nag Jung Elsevier 2019 Journal of cleaner production Vol.217 No.-

<P><B>Abstract</B></P> <P>Fly ash (FA) was considered as an adsorbent for adsorbing some harmful substances because of its unique characteristics such as high specific surface area, porosity, functional groups, unburned carbon content in the ash, etc. In this study, FA powder with polyacrylonitrile (PAN) matrix was electrospun into a multi-functional nanofibrous membrane for trapping of BTX aromatic hydrocarbons (benzene, toluene, and xylene) and heavy metal ions. These obtained FA/PAN composites possessed the satisfactory adsorption capacity for BTX aromatic hydrocarbons and heavy metal ions including Co(II), Pb(II) and Cr(VI). The performance of electrospun PAN-based FA nanofibrous membranes for trapping of BTX compounds and heavy metal ions was investigated with emphasis on the mechanisms, isotherms and kinetics. The impact of specific surface area, pore structure, porosity and functional groups on the adsorption behavior as well as adsorbate-adsorbent physicochemical interactions (e.g., electrostatic attraction, nonpolar attraction) were discussed. The results showed that all the tested materials had the strongest adsorption capacity for trapping of xylene, followed by toluene and benzene, and for trapping of heavy metal ions followed the order: Pb(II) > Co(II) > Cr(VI). The most exciting result is that although the trapping of BTX aromatic hydrocarbons by FA/PAN nanofibrous membrane was slightly lower than that by activated carbon (AC) powder, it was about 1.48 and 5.04 times higher than that by AC powder for trapping of Co(II) and Pb(II), respectively. In addition, the initial adsorption rate of FA/PAN membrane and FA powder for heavy metal ions was significantly faster than that of AC powder.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A cheap, durable and easy-to-use fibrous membrane was fabricated by electrospinning. </LI> <LI> Trapping of heavy metal ions by tested materials followed the order: Pb(II) > Co(II) > Cr(VI). </LI> <LI> Trapping of BTX aromatic hydrocarbons by tested materials followed the order: xylene > toluene > benzene. </LI> <LI> The adsorption mechanisms of fibrous composites were proposed accordingly. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Reducing volatile organic compound emissions from diesel engines using canola oil biodiesel fuel and blends

Ge, Jun Cong,Kim, Ho Young,Yoon, Sam Ki,Choi, Nag Jung Elsevier 2018 Fuel Vol.218 No.-

<P><B>Abstract</B></P> <P>Volatile organic compounds (VOCs), a group of environmental pollutants, are emitted in large quantities when fossil fuel is burned in automobiles. This research investigates the VOCs in the exhaust emissions from a common rail diesel engine fueled with canola oil biodiesel fuel (COBF), conventional diesel fuel (CDF), and B20 (20% COBF blended with 80% CDF by volume) at various engine loads (30 Nm, 80 Nm, 130 Nm) and a constant engine speed of 1500 rpm. The results indicate that the regulated emissions (CO, HC, PM) were reduced obviously when COBF and B20 were used in a CRDI diesel engine, and a larger number of VOCs (about 30 types) are emitted with CDF and the quantity emitted is greater than with B20 and COBF. The total VOC emissions (TVOC) of B20 were lower than those with the other test fuels at all experimental conditions. In addition, this paper presents a simple approach for sampling VOC emissions from diesel engines, uses a gas chromatography/mass spectrometry (GC/MS) analysis, and also confirms that COBF blended with CDF in a volume fraction of 20–80 is an excellent alternative fuel based on VOC emissions.</P>

Fabrication of low-cost and high-performance coal fly ash nanofibrous membranes via electrospinning for the control of harmful substances

Ge, Jun Cong,Kim, Ju Yeon,Yoon, Sam Ki,Choi, Nag Jung Elsevier 2019 Fuel Vol.237 No.-

<P><B>Abstract</B></P> <P>The use of a high-performance and low-cost electrospun nanofiber membrane to remove harmful pollutants from the air is highly valuable in terms of commercial applications. In this paper three functional materials were successfully fabricated into a low-cost, high-performance fibrous mat via a simple and one-step electrospinning technology. These materials included coal fly ash (CFA), which is an industrial waste mainly derived from coal-fired power plants with an adsorption capacity for adsorbing of volatile organic compounds (VOCs); silver nitrate (AgNO<SUB>3</SUB>), which imparts excellent antibacterial ability; and polyacrylonitrile (PAN), which serves as an electrospun substrate with high spin-ability. The binding properties of different amounts of CFA powder, AgNO<SUB>3</SUB> and PAN were observed and analyzed in detail by field emission scanning electron microscopy (FE-SEM), biological transmission electron microscopy (Bio-TEM), X-ray diffraction (XRD) and other experimental analyses. The results show that the PAN nanofibers containing 40 wt% CFA (relative to the weight of PAN) had the highest VOCs adsorption capacity compared with other membranes. Furthermore, 2 wt% AgNO<SUB>3</SUB> (relative to the weight of PAN) and 40 wt% CFA powder can be easily fabricated with and PAN nanofibers, and this electrospun PAN/CFA/AgNO<SUB>3</SUB> composite membrane has excellent antibacterial ability on Gram-negative <I>Escherichia coli</I> (<I>E. coli</I>) (ATCC 52922) and Gram-positive <I>Staphylococcus aureus</I> (<I>S. aureus</I>) (ATCC 29231) bacteria. These electrospun fibrous mats currently stand as an emerging material that has huge development potential for treatment of environmental pollutants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Multifunctional composite coal fly ash membranes are fabricated via electrospinning. </LI> <LI> VOCs adsorption effect is related to their own molecular structure and weight. </LI> <LI> Antibacterial activity mechanism of PAN/CFA/AgNO<SUB>3</SUB> membranes has been summarized. </LI> <LI> Electrospun coal fly ash membranes have huge potential in further application. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A Study on Application Characteristics of Canola Oil Biodiesel Fuel in a CRDI Turbocharged Diesel Engine

Jun-Cong Ge,Nag-Jung Choi 한국기계기술학회 2017 한국기계기술학회 학술대회논문집 Vol.2017 No.04

전통적인 화석 에너지 자원의 고갈과 환경오염 악화 등의 관점에서 볼 때 에너지 절약 및 배출가스의 저감은 동시에 해결해야 되는 문제로 대두되고 있다. 바이오연료는 대체연료의 하나로서 이러한 문제들을 효과적으로 해소할 수 있는 대안으로 떠오르고 있다. 따라서 본 연구에서는 커먼레일 터보과급디젤기관에 서 카놀라유 바이오디젤연료의 적용효과를 알아보기 위하여 실험적으로 고찰하였다. 실험에 사용된 연료 는 ULSD(초저황 디젤유), BD20(체적비로 20%인 카놀라유와 80% 디젤유 혼합) 및 PCO(순수한 카놀라 유)를 사용하였다. 카놀라유 바이오디젤연료의 혼합율이 증가함에 따라 입자상물질(PM)과 일산화탄소 (CO)는 크게 감소하였으며, 질소산화물(NOx)은 약간 증가하는 현상을 보였다. With depletion of conventional fossil energy resources and increased pollution, energy-saving and emission reduction problems have to be solved. Biofuels are alternative fuels that can effectively reduce these problems. Therefore, in this study, the application characteristics of canola oil biodiesel in a CRDI Turbocharged Diesel Engine was experimentally investigated. The test fuels were denoted as ULSD (ultra low sulfur diesel), BD20 (20% canola oil blended with 80% ULSD by volume), and PCO (pure canola oil), respectively. By using canola oil biodiesel, the particulate matter (PM) and carbon monoxide (CO) emissions were considerably reduced with increased BMEP. The nitrogen oxide (NOx) emissions increased only slightly due to the inherent presence of oxygen in biodiesel.

전기방사에 의한 PAN/FA 나노 복합재의 제조 및 휘발성 유기 화합물에 대한 흡착효과

갈준총(Jun Cong Ge),왕자건(Zi Jian Wang),윤삼기(Sam Ki Yoon),최낙정(Nag Jung Choi) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.6

휘발성 유기 화합물(VOCs: volatile organic compounds)은 대기 오염 물질 중 하나로 주로 화석연료 연소, 도료를 사용하는 건축물 자재 등에서 발생한다. VOCs를 흡입하면 두통, 메스꺼움, 구토 등을 발생시켜 인체에 유해하며 심한 경우에는 기억상실을 유발하고, 백혈병의 발병율을 증가시킨다. 따라서 대기 중의 VOCs를 저감하기 위한 방법의 하나로 우리는 전기방사를 이용하여 폴리아크릴로니트릴과 플라이 애쉬 (PAN/FA: polyacrylonitrile/fly ash) 나노복합재를 성공적으로 제조하였다. 또한 이 복합재의 VOCs에 대한 흡착능력을 관찰하기 위해서 주사형 전자현미경(FE-SEM)을 통해 PAN/FA 나노매트들의 형태학적 구조 관찰과 클로로폼, 벤젠, 톨루엔, 자일렌 (chloroform, benzene, toluene and xylene) 등 VOCs 성분에 대한 흡착력 실험을 수행한 후 정성 및 정량 (chromatography/mass spectrometry: GC/MS)적으로 분석하였다. 그 결과 40wt%의 FA가 들어있는 PAN 나노섬유가 가장 작은 섬유 지름을 가지고 있었으며, 그 크기는 약 283nm인 것을 확인할 수 있었고, 다른 복합 멤브레인들과 비교하여 VOCs에 대한 흡착력이 우수하다는 것을 실험적으로 규명하였다. Volatile organic compounds (VOCs), as a significant air pollutant, is generated mainly from the burning of fossil fuels, building materials using painting, etc. The inhalation of a certain amount of VOCs can be deleterious to human health, e.g., headaches, nausea and vomiting. In addition, it can also cause memory loss and even increase the rate of leukemia. Therefore, as one of the methods for reducing VOCs in air, polyacrylonitrile/fly ash (PAN/FA) composite nanofibrous membranes were fabricated by electrospinning. To observe their VOCs adsorption capacity, the morphological structure of PAN/FA nanofibrous mats was investigated by field emission scanning electron microscopy (FE-SEM), and the VOCs (chloroform, benzene, toluene, and xylene) adsorption capacity of PAN/FA membranes were tested by gas chromatography/mass spectrometry (GC/MS). The results indicated that the PAN nanofiber containing 40 wt. % FA powder had the smallest fiber diameter of 283 nm; they also showed the highest VOCs adsorption capacity compared to other composite membranes.

A study on performance of heat/water vapor recovery from flue gas with transport membrane condenser material

Cong Le Van,Jun Cong Ge,Sung Joo Hong(홍성주),Chan Woo Park(박찬우) 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2021 No.6

Preparation of Ultrasensitive Humidity-Sensing Films by Aerosol Deposition

Liang, Jun-Ge,Wang, Cong,Yao, Zhao,Liu, Ming-Qing,Kim, Hong-Ki,Oh, Jong-Min,Kim, Nam-Young American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.1

<P>Aerosol deposition (AD) is a novel ceramic film preparation technique exhibiting the advantages of room-temperature operation and highly efficient film growth. Despite these advantages, AD has not been used for preparing humidity-sensing films. Herein, room-temperature AD was utilized to deposit BaTiO<SUB>3</SUB> films on a glass substrate with a Pt interdigital capacitor, and their humidity-sensing performances were evaluated in detail, with further optimization performed by postannealing at temperatures of 100, 200, ..., 600 °C. Sensor responses (i.e., capacitance variations) were measured in a humidity chamber for relative humidities (RHs) of 20-90%, with the best sensitivity (461.02) and a balanced performance at both low and high RHs observed for the chip annealed at 500 °C. In addition, its response and recovery were extremely fast, respectively, at 3 and 6 s and it kept a stable recording with the maximum error rate of 0.1% over a 120 h aging test. Compared with other BaTiO<SUB>3</SUB>-based humidity sensors, the above chip required less thermal energy for its preparation but featured a more than 2-fold higher sensitivity and a superior detection balance at RHs of 20-90%. Cross-sectional transmission electron microscopy imaging revealed that the prepared film featured a transitional variable-density structure, with moisture absorption and desorption being promoted by a specific capillary structure. Finally, a bilayer physical model was developed to explain the mechanism of enhanced humidity sensitivity by the prepared BaTiO<SUB>3</SUB> film.</P> [FIG OMISSION]</BR>

An application of self-made ceramic membrane on transport membrane condenser for waste gas heat and wastewater recovery

Van Cong Le,Jun Cong Ge,Sung Joo Hong(홍성주),Chan Woo Park(박찬우) 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2019 No.-

Thickness effects of aerosol deposited hygroscopic films on ultra-sensitive humidity sensors

Liang, Jun-Ge,Kim, Eun-Seong,Wang, Cong,Cho, Myung-Yeon,Oh, Jong-Min,Kim, Nam-Young Elsevier 2018 Sensors and actuators. B Chemical Vol.265 No.-

<P><B>Abstract</B></P> <P>Hygroscopic film that has a super mesoporous structure exhibits high sensitivity and fast response/recovery in humidity sensing applications. Aerosol deposition (AD) via a shock-loading-solidification preparation mechanism, which is an unexplored potential hygroscopic film preparation technique, can produce a porous microstructure, and the AD hammering effect creates various interior and surface microstructures in different-thickness films. The objective of our study was to verify the feasibility of using AD as a humidity-sensing film preparation technique, and to investigate the thickness effects of the film on its microstructure and hygroscopic properties. Hygroscopic films with thicknesses ranging from 0.1–10.0 μm were aerosol deposited with BaTiO<SUB>3</SUB> powders before undergoing a 400 °C thermal treatment. The resulting surface morphology exhibited roughness increases for thicknesses from 0.1–6.0 μm, and a decrease at 10.0 μm. The cross-sectional structure was characterized by a transitional-density grain distribution in which higher density small-sized grains could be seen in the bottom layer. Films with thicknesses of 1.5 μm and 3.0 μm achieved excellent sensitivities of 178.6 ± 7.3 pF/%RH and 299.9 ± 5.4 pF/%RH, respectively. Further, the response and recovery time for the 1.5 μm film were both less than 5 s. The current study determined the feasibility of AD-based humidity-sensing film preparation and provided a reference for optimal thickness control. The surface hydrophilicity, pore volume, and open-pore ratio were analyzed as critical factors of the thickness related humidity sensing effects, and physical modeling indicated that AD-prepared films exhibited an expanded humidity detection range, enhanced water vapor adsorption and desorption, and improved sensitivity to humidity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aerosol deposition can be used to prepare ultra-sensitive ceramic humidity sensors. </LI> <LI> Film-based sensors were prepared using a shock-loading solidification mechanism of aerosol deposition. </LI> <LI> Their sensitivity depends on the hydrophilicity, pore volume, and open-pore ratio. </LI> <LI> The thickness of the film regularly affects the humidity-sensing properties. </LI> </UL> </P>

Integrated passive device fabricated and chip-on-board packaged filter employing mixed electric-magnetic coupling scheme

Liang, Jun-Ge,Wang, Cong,Kim, Nam-Young Institution of Electrical Engineers 2018 IET microwaves, antennas & propagation Vol.12 No.14