The use of Fenton and Fenton-like chemistry has found significant attention in water treatment for the degradation of organic contaminants, such as pharmaceuticals and pesticides. Iron catalysts are the traditional choice for Fenton chemistry, but copper also participates in this reaction cycle as a Fenton-like catalyst capable of efficient performance near neutral pH. Catalysts such as these can be attached to membrane support structures in order to function as reactive membranes. Additionally, atomic dispersion of metal catalysts enhances their catalytic performance and renders them attractive options in the environmental field. Herein, we created a thin film composite (TFC) reactive membrane for flowthrough water treatment. The polyamide TFC membrane was functionalized with thiol groups that anchor atomically dispersed copper to the membrane surface. Added hydrogen peroxide reacts with the copper in a Fenton-like cycle to produce hydroxyl radicals, which subsequently oxidize organic contaminants. In addition to the initial attachment, the exposed free thiol groups can reduce the used copper, returning the catalyst to its more active state. Using a hand-cast cellulose film, selected for its smooth surface and high density of hydroxyl groups, we examine the parameters impacting thiol-copper interactions and atomic dispersion, as opposed to nanoscale catalyst aggregation. Hydroxyl radical production, measured by terephthalic acid oxidation, results are used to optimize the selection of reducing agent used to achieve copper dispersion during synthesis, the thiol group density, and the thiol-copper ratio. These parameters are then used to elucidate the behavior of both the thiol groups and copper during the water treatment process. Film characterization, including EXAFS and XANES, compares the materials before and after the functionalized film’s use to show the changes in structure. Degradation experiments show that the atomically dispersed copper achieves 40-fold higher kinetics than its nanoparticulate counterpart and also has extended performance ability over time.

Atomically dispersed copper catalyst-functionalized polymeric membrane for organic contaminant degradation

ACS Fall 2021

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