Theses and Dissertations from UMD

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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

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Author: search.filters.author.Zheng, SunxiangSubject: search.filters.subject.Graphene Oxide

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    Silane Cross-Linked Graphene Oxide Membrane Demonstrating Unique Transport Phenomena in Aqueous Phase Separation
    (2015) Zheng, Sunxiang; Mi, Baoxia; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Graphene oxide (GO) membranes are considered promising for water purification applications. We synthesized a novel GO membrane using inorganic silane as a cross linker. Briefly, a pH 3 GO solution was filtrated through polyethersulfone (PES) membrane supports by vacuum filtration. The GO layers deposited on the PES supports were subsequently soaked in a saturated sodium metasilicate solution for crosslinking and stabilization. As a final step, the readily stabilized GO membranes were transferred into a 10% H2SO4 solution for further stabilization. The GO membrane exhibits unique rejection properties to uncharged organic species (~ 85%) and ionic species (~6%). A high water flux of 39 L/m2/h and a reasonable back solute flux of 0.011 mol/m2/h were observed with 0.25M trisodium citrate dehydrate (TSC) as draw solution in forward osmosis (FO). The GO membrane also demonstrates some interesting Janus effects and enables directional water gating (by blocking the permeation in one direction while allowing the permeation in the other direction).