Graphene oxide (GO) is typically produced by the oxidation of powdered graphite using Hummer's method. This process produces oxygenic defects in the 2-dimensional carbon lattice of graphene in the form of carboxylic acid, ketone, aldehyde, and epoxide groups. These functional groups may cluster to form metal ion binding sites. The focus of this project is to characterize the binding of Mn2+ by aqueous GO over a wide range of Mn2+ concentrations. Samples of buffered MnCl2/GO and buffered MnCl2 were analyzed using Electron Paramagnetic Resonance to determine the amount of bound and free Mn2+ ions. At low Mn2+ concentrations (10 µM - ~1000 µM) the binding can be described by a Langmuir isotherm binding model assuming two different types of binding sites, high affinity and low affinity. Both types of binding sites are sparse relative to the number of carbons present in the GO suspension. When higher concentration Mn2+ solutions (~2mM – 4mM) were introduced to GO, it appeared there was deviation from the Langmuir isotherm binding model and instead adherence to the BET multilayer binding model. The results of these studies and current work at higher concentrations of Mn2+ will be presented.

Characterizing divalent metal ion binding sites in graphene oxide with Mn(II) ions

251st National Meeting (2016)

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