title: Degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation.
abstract: The 2,4,6-trinitrotoluene (TNT) is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation (SCWO) to treat TNT contaminated wastewater was studied in this article. The TNT concentration in wastewater was measured by high-performance liquid chromatograph (HPLC) and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently in the presence of oxygen. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increased. At 550 degrees C, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occured in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO included toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously when TNT was oxidized by SCWO.
authors.affiliation: College of Chemical Engineering and Environment, North University of China, Taiyuan 030051, China. junchsh@163.com
authors.forename: Shuang-jun
authors.initials: SJ
authors.lastname: Chang
authors.forename: Yu-cun
authors.initials: YC
authors.lastname: Liu
mesh_terms: D053834:Explosive Agents / Q000737:chemistry*; D007220:Industrial Waste; D010084:Oxidation-Reduction; D011312:Pressure; D013696:Temperature; D013997:Time Factors; D014303:Trinitrotoluene / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D053834:Explosive Agents; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D014867:Water; D014303:Trinitrotoluene