Nitroguanidine (NQ) is a fundamental component of triple-base propellant and one of the main ingredients in insensitive munition (IM) formulations. Wastewater streams from IM production are usually characterized by residual nitroguanidine (NQ) as being one of the components with the highest solubility (2.5-6 g L-1); thus treatment before discharge is required. Although NQ has been used by the defense industry for several decades, little to no information are available in the literature regarding its removal from wastewater. In the present study, wastewater streams as well as synthetic solutions containing NQ were treated using UV-assisted hydrogen peroxide (H2O2), persulfate (PS) and (PMS) peroxymonosulfate advanced oxidation techniques. The advanced oxidation processes (AOPs) were investigated by comparing the degradation efficiency for NQ on a bench scale. The degradation kinetics of NQ for the oxidants was observed under different treatment conditions following identification and quantification of the carbon/nitrogen by-products. It was observed that direct UV photolysis could remove the NQ within one hour of continuous irradiation with a similar rate obtained in presence of the selected oxidants. However, significant differences were observed in the residual total organic carbon (TOC) and nitrogen by-products for the UV-assisted oxidation; in particular, PS and PMS obtained the highest removal of TOC, which suggests significant mineralization of NQ and related by-products. Guanidine and nitrate were identified as the main carbon and nitrogen by-products, followed by ammonia and nitrite. The outcomes of the described study provides encouraging and insightful basis for the application of some of the most common AOPs technique in the treatment of NQ contaminated wastewater streams.

Comparative evaluation of nitroguanidine removal by UV and oxidants: Hydrogen peroxide, persulfate, and peroxymonosulfate

2019 Fall National Meeting

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