Cleaning pollutants in wastewater is no easy task. But an innovative, cost-competitive electrode material designed to do just that has been developed by materials scientists and bioelectrochemical engineers at Cornell University.
Researchers created carbon nanofiber electrodes and applied a conductive polymer coating, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate, also known as PEDOT. The nanofibers provided a favorable surface for the growth of an electrically-active layer of bacteria, Geobacter sulfurreducens, that digests pollutants and creates electricity. Under the microscope, the electrodes look like kitchen scrubbers.
The carbon nanofibers are fabricated by carbonization processes and electrospinning – a technique that produces a thick nanofiber sheet, visible to the naked eye, within a matter of a few hours. The nanofiber electrode is used for its surface area, high porosity and bacterial biocompatibility.
Study co-lead author Juan Guzman, a doctoral candidate in biological and environmental engineering at Cornell, noted that wastewater treatment plants do not employ this method – not yet, that is. "Electrodes are expensive to make now, and this material could bring the price of electrodes way down, making it easier to clean up polluted water," he said. On a large scale, bacteria could capture and degrade wastewater pollutants as they flow by. This would allow wastewater treatment systems to increase throughput, and take up less land.
The electrode was made by study co-lead author Meryem Pehlivaner, a doctoral student at Northeastern University, along with senior author and fiber science professor Margaret Frey, an associate dean of the College of Human Ecology. For help with applying the electrodes to produce electricity while at the same time treating wastewater, Pehlivaner reached out to two biological and environmental engineering scientists – Guzman and senior author Prof. Lars Angenent.
Angenent said that concepts like this happen when faculty and students want to communicate and collaborate. “We have fiber scientists talking to environmental engineers, from two very different Cornell colleges, to create reality from an idea that was more or less a hunch.”