This research investigates the removal of a series of p-substituted phenols (p-nitrophenol, p-methoxyphenol, p-benzoquinone) using a porous substoichiometric titanium dioxide (Ti4O7) reactive electrochemical membrane (REM) operated in cross-flow filtration mode. Experimental results indicate that the three compounds were completely removed upon a single pass through the REM, but showed varying affinities for intermediate compound adsorption.  Density functional theory (DFT) and mass transport modeling were used to interpret experimental results.  DFT results indicate that competing oxidation mechanisms (direct oxidation versus indirect oxidation with OH�) could explain experimental trends, and the differences in intermediate adsorption was related to the anodic potential at which direct oxidation occurred.  Mass transport modeling was used to investigate reactivity of the REM with membrane depth.  Results indicate that the oxidation of water to form OH� and the direct oxidation of p-substituted phenols occurred over a different membrane depth, which was controlled by the potential drop in the membrane pores.  The implications of these results for compound oxidation and further REM development are discussed.

Mechanistic investigation of p-substituted phenol removal on substoichiometric titanium dioxide reactive electrochemical membranes

247th National Meeting (2014)

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