Abstract

Millions of tons of nitroaromatic explosives are produced worldwide for military purposes and other applications. These substances lead to the accidental release of energetic materials, resulting in soil and groundwater pollution. Nitroaromatics are easily reducible because of their polarized N-O bands. Therefore, they are not sorbed strongly in the environment due to the intermediate character between hydrophobic and hydrophilic properties. Advanced oxidation processes (AOPs) have recently been used to degrade emerging pollutants due to generating highly oxidizing agents, such as hydroxyl radical. The main objective of this study is to examine the possibility of the persulfate/ozone (as an activator) process in explosive degradation from an aqueous solution. Experiment designs and data analysis were evaluated using the Taguchi design method considering COD and TOC removal as responses. Next, 2,4,6-trinitrotoluene (TNT) residual concentration was detected using the HPLC instrument. Finally, the most significant parameters that affected response removal were determined by variance (ANOVA) analysis. A satisfactory agreement of the quadratic model with the experimental data was confirmed by the high R-2 value (close to 1). The correlation coefficient of 0.9 indicates the high validity of the obtained models for removing COD and TOC. Hence, in removing COD and TOC, a very good agreement was found between the experimental values and the predicted values of the responses. Two-third of 2,4,6-trinitrotoluene was transferred to inorganic compounds corresponding to CO2 due to the generation of oxidative species. More than 72 COD and 65 TOC removal efficiency were obtained in 60 min employing pH neutral, PS 19 mM, and 40 mg/L TNT (k(t) = 0.0191 min(-1), pseudo-first-order kinetic model). Overall, sulfate radicals activated by ozone could be considered a promising process for nitroaromatic degradation of industrial effluent.