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Abstract: Surface modification of the membrane has been adopted in membrane technology for tuning pore structure, hydrophilicity, and electro-conductivity. Among various coating methods, atomic layer deposition (ALD), a sub-nanometer thickness coating technique is gaining its popularity recently as it does not decline separation performance while functionalizes membrane’s surface properties. However, its specific and precise coating process based on the substrate’s condition has not been yet investigated for optimum functionalization of the membrane. Therefore, we developed a surface functionalized graphene oxide (GO) membrane via plasma-enhanced ALD method. This membrane was designed for use as a nanofiltration (NF) in a salt water desalination where common permeability-selectivity trade-offs occurs. Therefore, unlike conventional ALD approaches, to functionalize the surface without increasing the membrane thickness, we conducted only a few (3–9) ALD cycles, which allowed for the formation of a tunable ultra-thin (1.44 nm) and uniform hydrophilic metal oxide (Al2O3) layer on the multi-layered membrane. The concept of this new membrane has not been reported previously. Atomic level surface functionalization showed promising advantages over laminarly stacked GO membrane, in terms of both water permeability and NaCl rejection. Trimethylaluminum was used as precursor as our target deposition component is Al2O3 that shows strong chemisorption to GO. In particular, Al2O3 deposition by ALD on GO membrane surface provided hydrophilicity and changes in functional groups with thickness growth within 1nm. As oxygen-containing functional groups of ALD-Al2O3 hindered GO’s carbon related functional groups, more NaCl rejection were occurred due to the electrostatic interaction between membrane surface and salt ion. The main task regarding GO membrane for desalination application is to break permeability-selectivity trade-offs. In this study, through low number of ALD cycles (3~30), Al2O3 was successfully deposited on the membrane, exhibiting maximum deposition thickness of 5.12 nm. Water flux and salt rejection increased from 198.4 L/m2/h to 362.6 L/m2/h and 48.6% to 67.4% for pristine GO membrane and 9 ALD cycles on GO membrane, respectively. However, permeate flux drastically decreased after 9 cycles because ALD blocked the water passage channel. 

Biography: Prof. Kyu-Jung Chae is a Full Professor of Environmental Engineering at Korea Maritime and Ocean University, and also serves as a Vide-Dean of the College of Ocean Science and Engineering. He received a Ph.D. from Gwangju Institute of Science and Technology (GIST), in Environmental Engineering, 2010. After obtaining a doctorate, he worked at Kolon Global Corp., a leading company in environmental sectors in South Korea, as a principal researcher and licensed Professional Engineer. Since 2014, he has been working as a professor at Korea Maritime and Ocean University (KMOU). 

As of 2021, renowned for his pioneering research, he has led more than 30 research projects as a principal investigator, published over 121 papers for highly ranked peer-reviewed journals, 3 books, and achieved 40 patents. In addition, he developed many New Excellent Technologies certified by Korean government and successfully commercialized those technologies in the industrial fields. The strongest point which makes him a unique researcher compared to other scientists is his extensive and balanced experiences in both academia and industry for over 21 years since 2000, so that he knows well the real needs in environmental research in both fundamental and practical aspect based on his balanced experience. His areas of expertise span a wide range of environmental science and technology, including water-energy nexus technology, bioelectrochemical cells, energy self-sufficient wastewater treatment, membrane bioreactor, microbial fuel cells, environmental nano-materials, advanced wastewater treatment, and marine pollution.