Emerging Contaminants Summit

Spring 2020

StudentCompetitionshroerHunter Schroer
Research Fellow 
University of Iowa

Hunter is finishing his PhD in Environmental Engineering at the University of Iowa in May 2018. Hunter has received awards such as the NSF Graduate Research Fellowship and an ACS Environmental Chemistry Division Graduate Student award. Hunter has published in Environmental Science & Technology and Environmental Science & Technology Letters, and is actively searching for jobs in the Denver area.



Photolysis of 3-Nitro-1,2,4-Triazol-5-One (NTO): Mechanisms, Products, and Renitration of Guanidine

New insensitive munitions explosives, including 3-nitro-1,2,4-triazol-5-one (NTO), are replacing traditional explosive compounds to protect soldiers and simplify transport logistics. Despite the safety benefits of these new explosives, little is known about behavior and toxicity of NTO in the environment. Here, we evaluate the photolysis of NTO in aqueous solution to determine the feasibility of treating production wastewater with UV light and to understand the potential rates and mechanisms of NTO photolysis in surface waters. We observed that direct photolysis of NTO is faster with increasing pH and oxygen content of the solution. Experiments with Suwannee River Natural Organic Matter revealed that indirect photolysis of NTO is not important, and increasing natural organic matter slows NTO transformation. Direct photolysis of NTO yields singlet oxygen, as evidenced by degradation of the probe compound furfuryl alcohol (FFA) upon NTO photolysis and by slowing of direct photolysis and FFA degradation in the presence of sodium azide. Addition of sorbic acid dramatically slows direct photolysis of NTO, indicating that the reaction proceeds through a triplet excited state. We have detected two volatile unknowns by gas chromatography (GC)-electron capture detection, and are working to characterize and quantify these reaction products by GC-mass spectrometry. Finally, we will present total carbon and nitrogen balances of NTO photolysis and environmental conditions that promote renitration of guanidine during photolysis of nitroguanidine and NTO mixtures.

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