Effective treatment of 2,4,6-trinitrotoluene from aqueous media using a sono–photo-Fenton-like process with a zero-valent iron nanoparticle (nZVI) catalyst

Abstract

In this study, we examine the effectiveness of using a combination of a sono–photo-Fenton-like procedure and nano zero-valent iron catalyst (nZVI) to treat 2,4,6-trinitrotoluene (TNT) in an aquatic environment. Zero-valent iron particles were generated by a chemical reduction technique. nZVI nanoparticles were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) to characterize the nanocatalyst. The resulting nZVI nanoparticles were used as an addition in a sono–photo-Fenton method to remediate an aqueous solution contaminated with TNT. Furthermore, influences of operational factors such as temperature, catalyst dosage, wavelength, ultraviolet power, ultrasonic frequency and power, pH level, H₂O₂/nZVI ratio, initial TNT concentration, and reaction duration on the treatment of TNT were investigated. Under the conditions of an ideal pH of 3, temperature range of 40–45 °C, concentration of 50 mg per L TNT, dose of 2 mM of nZVI, and ratio of H₂O₂/Fe⁰ of 20, a treatment efficiency of 95.2% was achieved after a duration of 30 minutes. The sono–photo-Fenton process combined with nZVI showed a higher TNT removal efficiency compared to the Fenton, sono-Fenton, and photo-Fenton processes under the same conditions. Moreover, it promises a potential solution to treat TNT at the pilot scale while allowing reuse of the nZVI catalyst and the limitation of sludge.