Pulsed-Waveform Electrocatalytic Remediation of Pfas-Contaminated Aqueous Streams

Abstract

Per-/polyfluorinated alkyl species (PFAS) have historically been used across a broad range of industries for a wide variety of applications, including carpeting, apparel, upholstery, metal plating and firefighting foams. However, research has demonstrated that these compounds are highly refractory and bio-accumulative when released to the environment, and have the potential to cause adverse health effects, such as low birth weight, accelerated puberty, cancer, and skeletal, liver, kidney and other problems. Thus, recently the EPA established a lifetime advisory level for all potentially-harmful PFAS at 70 parts-per-trillion (ppt). Existing state-of-the-art treatment techniques such as sorption by activated carbon work in certain circumstances but are extremely costly, often cannot be used for waste streams with complex composition, and ultimately are not a long-term solution, as they create in turn a waste stream of PFAS-laden adsorbent that must be treated. Thus, it is desirable to develop an energy and cost-efficient technology for degradation of PFAS in various industrial waste streams, landfill leachates, soil-derived streams, etc., which does not also generate auxiliary PFAS-laden waste.We are currently working to demonstrate a pulsed-waveform electrocatalysis approach for PFAS destruction yielding destruction performance superior to direct-current electrocatalytic methods. In preliminary tests with a boron-doped diamond (BDD) electrocatalyst, pulsed-waveform electrocatalysis exhibited perfluorooctane sulfonate (PFOS) destruction of 97%+ within one hour of processing in multiple solution matrices. Cost analysis estimates indicate that the use of pulsed waveforms has the potential to provide appreciable increases in electrocatalytic destruction performance, potentially enabling significant reductions in both CAPEX and OPEX, providing an overall cost structure that appears favorable for deployment of this technology for destruction of PFAS in various streams, including drinking water, electroplating rinse waters, landfill leachates and groundwater. This talk will focus primarily on the performance enhancements observed from the use of pulsed-waveform versus direct-current electrocatalytic methods for destruction of multiple PFAS over BDD electrocatalysts, with discussion of other parameters observed to significantly affect process performance (flow rate, temperature, electrolyte composition, etc.) included where relevant.The authors acknowledge financial support from U.S. EPA Contract Nos. 68HERD-19-C-0011, 68HERD-19-C-0023, 68-HERC-20-C-0054, and 68-HERC-20-C-0058.