(595c) Reactive Membranes for the Degradation of Emerging Wastewater Contaminants

Membrane systems offer a highly effective means of water purification; however, some harmful contaminants cannot be removed by this technology. These emerging contaminants include carcinogenic compounds such as N-nitrosodimethyalmine (NDMA) and 1,4-dioxane. Traditionally, removal of such chemicals would require a separate process to allow for their oxidative degradation. Therefore, the objective of this project is to develop modified membranes capable of oxidizing such emerging contaminants at the membrane surface, allowing for wastewater treatment to be accomplished in a single stage.

A widely employed and broadly effective advanced oxidation process used in wastewater treatment is the Fenton process, which relies on the catalytic decomposition of hydrogen peroxide to generate reactive free radical species for the oxidation of organic molecules. The reactive membranes used here were modeled on previously developed anti-fouling reverse osmosis and nanofiltration membranes. A polydopamine coating was applied to the membrane surface, creating a layer capable of embedding copper oxide nanoparticles. These particles then served as a catalyst for the decomposition of hydrogen peroxide added at low concentrations to the influent stream, thereby generating the same reactive species employed in Fenton oxidation. Availability of these species near the membrane surface allowed oxidation of organic compounds to occur before they could pass through the membrane, while the polydopamine layer scavenged excess radicals to protect the membrane itself from degradation. The efficacy of the modified membranes was tested against NDMA and 1,4-dioxane as model contaminants.