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Baek, Youngbin,Freeman, Benny D.,Zydney, Andrew L.,Yoon, Jeyong American Chemical Society 2017 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.56 No.19
<P>Polydopamine (PDA) is widely used to modify the membrane surface to increase the hydrophilicity with the goal of producing a low fouling membrane. However, current methods of PDA modification require alkali conditions and relatively long reaction times. Herein, we introduced the use of UV irradiation during the PDA modification of the membrane surface. The effects of UV irradiation on the characteristics of the synthesized PDA and the performance of the resulting membrane were evaluated. The PDA was rapidly synthesized in DI water, providing a significant increase in hydrophilicity and a reduction in surface roughness of the polyamide reverse osmosis (RO) membranes. The PDA-modified RO membranes exhibited excellent antifouling behavior upon exposure to alginate while maintaining good water permeability and salt rejection. The use of UV allowed the PDA modification to be conducted in DI water in less than 30 min, a significant improvement compared to current methods.</P>
Oxygen Concentration Control of Dopamine-Induced High Uniformity Surface Coating Chemistry
Kim, Hyo Won,McCloskey, Bryan D.,Choi, Tae Hwan,Lee, Changho,Kim, Min-Joung,Freeman, Benny D.,Park, Ho Bum American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.2
<P>Material surface engineering has attracted great interest in important applications, including electronics, biomedicine, and membranes. More recently, dopamine has been widely exploited in solution-based chemistry to direct facile surface modification. However, unsolved questions remain about the chemical identity of the final products, their deposition kinetics and their binding mechanism. In particular, the dopamine oxidation reaction kinetics is a key to improving surface modification efficiency. Here, we demonstrate that high O<SUB>2</SUB> concentrations in the dopamine solution lead to highly homogeneous, thin layer deposition on any material surfaces via accelerated reaction kinetics, elucidated by Le Chatelier’s principle toward dopamine oxidation steps in a Michael-addition reaction. As a result, highly uniform, ultra-smooth modified surfaces are achieved in much shorter deposition times. This finding provides new insights into the effect of reaction kinetics and molecular geometry on the uniformity of modifications for surface engineering techniques.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-2/am302439g/production/images/medium/am-2012-02439g_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am302439g'>ACS Electronic Supporting Info</A></P>
Maximizing the right stuff: The trade-off between membrane permeability and selectivity
Park, Ho Bum,Kamcev, Jovan,Robeson, Lloyd M.,Elimelech, Menachem,Freeman, Benny D. American Association for the Advancement of Scienc 2017 Science Vol.356 No.6343
<P>Increasing demands for energy-efficient separations in applications ranging from water purification to petroleum refining, chemicals production, and carbon capture have stimulated a vigorous search for novel, high-performance separation membranes. Synthetic membranes suffer a ubiquitous, pernicious trade-off: highly permeable membranes lack selectivity and vice versa. However, materials with both high permeability and high selectivity are beginning to emerge. For example, design features frombiological membranes have been applied to break the permeability-selectivity trade-off. We review the basis for the permeability-selectivity trade-off, state-of-the-art approaches to membrane materials design to overcome the trade-off, and factors other than permeability and selectivity that govern membrane performance and, in turn, influence membrane design.</P>
High-performance CO<sub>2</sub>-philic graphene oxide membranes under wet-conditions
Kim, Hyo Won,Yoon, Hee Wook,Yoo, Byung Min,Park, Jae Sung,Gleason, Kristofer L.,Freeman, Benny D.,Park, Ho Bum The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.88
<P>Ultrathin graphene oxide (GO) (<5 nm) membranes were prepared by spin-casting onto microporous polymeric support membranes. GO membranes exhibited a highly CO<SUB>2</SUB> permeable character, which is suitable for CO<SUB>2</SUB> separation. In the presence of water vapour, high CO<SUB>2</SUB> selectivity (<I>e.g.</I>, CO<SUB>2</SUB>/H<SUB>2</SUB>, CO<SUB>2</SUB>/N<SUB>2</SUB>, and CO<SUB>2</SUB>/CH<SUB>4</SUB>) was achieved by enhanced CO<SUB>2</SUB> sorption.</P> <P>Graphic Abstract</P><P>Ultrathin graphene oxide (GO) (<5 nm) membranes were prepared by spin-casting onto microporous polymeric support membranes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc06207h'> </P>