Research Assistant Professor
Colorado State University
Dr. Jens Blotevogel is a Research Assistant Professor of Civil & Environmental Engineering at Colorado State University. He holds a PhD in Environmental Chemistry from CSU and a Diploma in Environmental Engineering from the Technical University Berlin. Dr. Blotevogel’s research interests revolve around the fate of emerging contaminants. He has developed innovative water treatment technologies, theoretical models for contaminant fate prediction, as well as various analytical techniques with focus on high-resolution mass spectrometry. He is currently working on solutions for managing per- and polyfluoroalkyl substances (PFAS), 1,4-dioxane, nitroaromatic compounds, petroleum hydrocarbons, and oil and gas produced water.
An Efficient Nanofiltration - Electrochemical Oxidation Treatment Train for the PFOA Replacement Chemical GenX
Hexafluoropropylene oxide dimer acid (trade name GenX) is a perfluoroalkyl ether carboxylic acid (PFECA) that has been detected in watersheds of North America, Asia, and Europe. Similar to other per- and polyfluoroalkyl substances (PFASs), very few processes are able to break its persistent carbon-fluorine bonds. Here we provide both experimental and theoretical lines of evidence for GenX mineralization during electrochemical oxidation at a boron-doped diamond anode with a low potential for the generation of stable intermediates. While the ether bond is the weakest linkage in PFECAs, we show that this bond remains intact during initial oxidative attack. Rather, oxidation starts at the acidic side chain, successively leading to complete mineralization. Our mechanistic investigations reveal that hydroxyl radicals are unreactive towards GenX, while electrochemically generated sulfate radicals facilitate its oxidation. This suggests the possibility that activated persulfate may be an alternative treatment approach. Furthermore, we demonstrate that a NF90 membrane is capable of removing 99.5% of GenX from contaminated water, and thus is possibly able to meet current health goals at typical environmental concentrations. Electrochemical treatment of the nanofiltration rejectate is shown to reduce both energy and electrode costs by more than one order of magnitude compared to direct electrochemical treatment of the raw water. Overall, a nanofiltration - electrochemical oxidation treatment train is a viable and sustainable destructive approach for cost-effective elimination of GenX and other PFASs from contaminated water.
Bioelectrochemical Oxidation of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foams (AFFFs)
Electrochemical oxidation is one of the few water treatment technologies that can mineralize perfluoroalkyl sulfonic acids (PFSAs). To enhance the energy efficiency of the electrochemical process, we investigated the performance of a combined treatment train with biological transformation of AFFF constituents both by the fungus Trametes versicolor and by pure laccase enzymes. In addition to quadrupole time-of-flight (QTOF) and triple-quadrupole (QQQ) mass spectrometry, we applied ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for non-targeted tracking of PFAS “dark matter”. While the most persistent PFSAs were eventually oxidized at a boron-doped diamond anode, their degradation only set in once poly- and non-fluorinated species had been fully removed. Both fungi and enzymes were capable of degrading poly- and non-fluorinated AFFF components over 19 days. In addition, laccase partially removed PFSAs. Thus, biological pre-oxidation of readily biodegradable species has the potential to greatly improve electrochemical AFFF treatment efficiency. Our results demonstrate that a bioelectrochemical treatment train is a promising approach for sustainable destruction of PFASs in complex AFFF groundwater plumes.