Determination of Optimum Conditions for the Degradation of 2,4,6-Trinitrotoluene (TNT) by Advanced Reduction Processes

Abstract

Advanced Reduction Processes (ARP) are emerging technology that allows the breakdown of oxidation-resistant pollutants by producing reductant radicals such as hydrated electrons (eaq-) and hydrogen radicals (H center dot). Because of that, it is a suitable treatment method for recalcitrant compounds such as 2,4,6-trinitrotoluene (TNT). Although the requirements of the process cannot be fully defined, it's promising for wastewater treatment due to its short reaction times and easy operation. In this study, the TNT degradation efficiency of UV (253.7 nm wavelength) combined with reducing agents such as sulfite, dithionite, and sulfide was investigated. Important process parameters such as agent selection, pH, agent dose, initial TNT concentration, and UV intensity were optimized. Almost 100% TNT removal was observed by dithionite/UV process after 30 min under optimum conditions (1.5 mM dithionite, pH = 7, 8000 mu W/cm2 UV, initial TNT concentration = 25 mg/L). For dithionite, molar absorption and quantum yield for TNT were calculated at 254 nm wavelength epsilon = 87.33 1/M center dot cm and phi = 0.199 mol/Einstein, respectively.