Graphene materials are increasingly being incorporated into water treatment technologies due to their rapid and non-selective sorption abilities to small molecular weight organic contaminants.  This study examines some of the mechanistic interactions between commercial graphene oxides and endocrine disrupting compounds, pharmaceuticals, and natural organic matter in order to determine which physicochemical properties should be considered when choosing a graphene material.  Graphene oxides of varied particle sizes, specific surface areas, and surface chemistries were evaluated within batch reactors.  Specific surface area (SSA), surface charge, and phenolic content of graphene oxides was determined to have the greatest control on sorption extent of carbamazepine, an anticonvulsant used as a probe compound.  Only graphene with SSA much larger than 100 m2g-1 could out-compete granular activated carbon or multi-walled carbon nanotubes, other carbonaceous sorbents currently used in water technologies.   Pi-pi dispersion interactions appear to govern sorption of neutral compounds, and electrostatic interactions also strongly influenced cationic and anionic compounds, increasing or decreasing sorption two-fold, respectively, as graphene surface charge becomes more negative at higher pH.   Sorption extents for various humic acids, fulvic acids, and organic matter showed good correlation with aromatic content, indicating a preference for the more hydrophobic fraction.  A concomitant decrease in specific UV absorbance was also observed. Size exclusion chromatography revealed a preference for sorption of the larger molecular weight fraction. Enhanced or diminished sorption of organic compounds in the presence of organic matter depended on compound charge.

Factors influencing organic contaminant and natural organic matter sorption onto graphene oxide

248th National Meeting (2014)

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