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정승철 ( Seungcheol Jeong ),이병희 ( Byonghi Lee ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-
하수처리는 물리적, 화학적, 생물학적 처리의 복합공정을 통하여 이루어지며 사회적 요구에 의해 보다 고도화되어 왔다. 하수처리장 모델링은 초기 유기물 제거하수처리의 핵심공정으로서 활성슬러지법에 모델링이 1970년대 후반에 제안되어 1982년도 IWA에 의해 정식으로 제안되었다. 이후 ASM No.1에서 질소제거가 포함되고 ASM No.2에서 인제거 공정이 추가되었다. 모델링은 프로세스의 거동을 전산모사에 의해 재현하는 것으로 하수처리장의 설계, 유지관리의 최적화에 기여한 바가 크다. 그러나, 최근의 하수처리 공법은 고도화, 에너지 자립형을 요구하면서 과거 유기물, 질소, 인 제거를 중심으로 한 모델을 가지고 각 처리장의 고유 조건을 고려한 프로세스나 운전조건의 최적화를 예측하는 것이 어렵게 되었다. 이를 극복하기 위해서는 모델링에 의한 예측값의 현장 운영데이터와의 검증, 필요한 데이터의 보정방법에 대한 이론적 이해 및 개별 단위공정과 전체공정의 연관성 구현, 프로그램으로서의 효용도를 높이기 위한 사용법의 개발 등이 이루어져야 한다.
Yang, SeungCheol,Kim, Won-Sik,Choi, Jiyeon,Choi, Young-Woo,Jeong, Namjo,Kim, Hanki,Nam, Joo-Youn,Jeong, Haejun,Kim, Yong Ho Elsevier 2019 Journal of membrane science Vol.573 No.-
<P><B>Abstract</B></P> <P>The utilization of large amounts of volatile organic solvents and the complicated process required for industrial manufacturing of ion-exchange membranes necessitate the development of simple, rapid, and environmentally friendly fabrication methods such as those based on photopolymerization. We employed hydrolytic sol–gel reactions between ammonium- and acrylamide-functionalized silane coupling agents to synthesize water-soluble siloxane resins that exhibit high condensation levels (>80%) and comprise oligomers with molecular weights below 2000 Da. These resins were then mixed with a hydrophilic monomer bearing ammonium and acrylamide groups, and porous polyethylene substrates were impregnated with the resulting mixtures and then irradiated with ultraviolet light. The hydrophilicity, mechanical strength, and other properties of the resulting membranes depended on the resin composition, indicating that the substrate pores were efficiently filled with the prepared resins and further suggesting that the membrane performance could be effectively altered by varying the resin composition. Moreover, the obtained membranes exhibited chemical stability in the pH range between 0 and 11 and in hot water at 60 °C. The reverse electrodialysis stack consisting of these membranes showed higher power density than a stack of commercial membranes. Therefore, it can be concluded that without employing volatile organic solvents for reverse electrodialysis, the developed technique is well-suited for the fabrication of ion-exchange membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photocured anion-exchange membranes were fabricated using water-soluble siloxane resins. </LI> <LI> All resins had a high condensation degree, containing oligomers with <I>M</I> <SUB>w</SUB> < 2000 Da. </LI> <LI> These resins acted as cross-linkers and helped to avoid the use of organic solvents. </LI> <LI> The properties of the prepared anion-exchange membranes depended on resin composition. </LI> <LI> Reverse electrodialysis using the prepared membrane shows higher power density than that of the commercial membrane. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Jeong, Namjo,Kim, Han-ki,Kim, Won-sik,Choi, Ji Yeon,Han, Ji-hyung,Nam, Joo-youn,Hwang, Kyo Sik,Yang, SeungCheol,Jwa, Eun-Jin,Kim, Tae-Young,Park, Soon-Chul,Seo, Yong-Seog,Kim, Sung-in Elsevier 2019 Chemical engineering journal Vol.356 No.-
<P><B>Abstract</B></P> <P>The direct integration of two-dimensional nanostructures into macroscopic porous carbon substrates is essential for their practical use in potential applications, which is a big challenge due to the difficulty of securing uniform coating layers. In this work, we demonstrate a very simple and effective method for the direct coating of MoS<SUB>2</SUB> onto the surface of porous carbon structures having nano-sized pores, such as vertically aligned carbon nanotube arrays. A uniform coverage of MoS<SUB>2</SUB> over carbon substrates was achieved by chemical vapor deposition of gaseous species derived from starting precursors in a closed reactor. Transmission electron microscopy images, X-ray diffraction data, and Raman spectra confirmed the formation of highly crystalline MoS<SUB>2</SUB> layers. X-ray photoelectron and energy dispersive X-ray spectroscopies revealed highly uniform MoS<SUB>2</SUB> layers over the whole surface of the carbon substrates. Our approach is also applicable for the synthesis of MoS<SUB>2</SUB>/carbon fiber paper (CFP) hybrid structures. The electrochemical tests showed that the as-synthesized MoS<SUB>2</SUB>/CFP structures can serve as highly active cathodes for reverse electrodialysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MoS<SUB>2</SUB>@VCNT and MoS<SUB>2</SUB>@CFP were prepared in this work. </LI> <LI> Uniform MoS<SUB>2</SUB> coating was achieved by CVD of gaseous species in the closed reactor. </LI> <LI> This approach is very powerful for MoS<SUB>2</SUB> coating over macroscopic porous substrates. </LI> <LI> MoS<SUB>2</SUB>/CFP can be a highly active cathode for reverse electrodialysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Flow-Electrode Capacitive Deionization Using an Aqueous Electrolyte with a High Salt Concentration
Yang, SeungCheol,Choi, Jiyeon,Yeo, Jeong-gu,Jeon, Sung-il,Park, Hong-ran,Kim, Dong Kook American Chemical Society 2016 Environmental science & technology Vol.50 No.11
<P>Flow-electrode capacitive deionization (FCDI) is novel capacitive deionization (CDI) technology that exhibits continuous deionization and a high desalting efficiency. A flow electrode with high capacitance and low resistance is required for achieving an efficient FCDI system with low energy consumption. For developing high-performance flow-electrode, studies should be conducted considering porous materials, conductive additives, and electrolytes constituting the flow-electrode. Here, we evaluated the desalting performances of flow-electrodes with spherical activated carbon and aqueous electrolytes containing various concentrations of NaCl in the FCDI unit cell for confirming the effect of salt concentration on the electrolyte of a flow-electrode on desalting efficiency. We verified the necessity of a moderate amount of salt in the flow-electrode for compensating for the reduction in the performance of the flow-electrode, attributed to the resistance of water used as the electrolyte. Simultaneously, we confirmed the potential use of salt water with a high salt concentration, such as seawater, as an aqueous electrolyte for the flow-electrode.</P>