Selective removal of nitroaromatic compounds from wastewater in an integrated zero valent iron (ZVI) reduction and ZVI/H₂O₂ oxidation process

Abstract

In this study, an integrated system comprised of zero-valent iron (ZVI) reduction and ZVI-based Fenton oxidation processes (ZVI-ZVI/H 2 O 2 ) was applied for the selective removal of nitroaromatic compounds (NACs) from 2,4-dinitroanisole (DNAN) producing wastewater. For the ZVI reduction process, at a hydraulic retention time (HRT) of 6 h and neutral pH of 7.2, removal efficiencies of 2,4-dinitroanisole (DNAN), 2,4-dinitrophenol (DNP) and 2,4-dinitrochlorobenzene (DNCB) were as high as 81.3 AE 3.6%, 80.6 AE 1.8% and 90.9 AE 3.5%, respectively, demonstrating the excellent performance of ZVI. For the ZVI/ H 2 O 2 oxidation process, the optimal pH and H 2 O 2 dosage were found to be 3.0 and 100 mmol L À1 , respectively. Under these optimal conditions, NACs and their degradation intermediates could be removed selectively and effectively in the coupled ZVI reduction and ZVI/H 2 O 2 oxidation process, as was indicated by the low UV 254 value of 0.104 AE 0.003 and the low TOC removal efficiency of 32.4 AE 0.7% in the effluent. Ferrous ions could be generated in situ through the corrosion of the metal iron in both the ZVI reduction process and the ZVI/H 2 O 2 oxidation process, giving rise to a potent Fenton-type reaction.In addition, the enhanced Fenton reaction with the aid of reaction between Fe 0 and Fe 3+ was probably due to the presence of Fe 0 in the ZVI/H 2 O 2 oxidation process, which promoted the utilization efficiency of the Fenton catalyst, i.e., Fe 2+ . Compared to the sequential ZVI reduction and homogeneous Fenton oxidation process (ZVI-Fe 2+ /H 2 O 2 ), the low consumption of iron shavings, the reduced H 2 O 2 consumption and the low yield of ferric sludge made the integrated ZVI-ZVI/H 2 O 2 process promising for the treatment of NAC containing wastewater.

Strategies to Drive Photo-Fenton Process at Mild Conditions for the Removal of Xenobiotics from Aqueous Systems

“…For this purpose, the process is driven with and without hydrogen peroxide. The reductive step is commonly employed to remove deactivating functional groups, namely nitroaromatics [97,98]. Then, addition of hydrogen peroxide and irradiation (photo-Fenton step) is used to deal with the more easily oxidizable aminoaromatics.…”

Characterization of Mg-based bimetal treatment of insensitive munition 2,4-dinitroanisole

“…In addition, extensive research on the degradation of DNAN in IM wastewater has been conducted. These studies have evaluated various technologies including: phytoremediation (Shih et al, 2009), aerobic biodegradation (Fida et al, 2014), ZVI/Fenton treatment (Liu et al, 2015), ZVI/anaerobic digestion (Ahn et al, 2011), Fe/Cu bimetal/Fenton treatment (Shen et al, 2013), and reduction by Fe/Cu (Koutsospyros et al, 2012;Kitcher et al, 2017). Treatment of DNAN by bimetals typically exhibits several advantages when compared to other technologies including extremely rapid degradation kinetics leading to high removal efficiency.…”

“…coating) with a catalytic metal to create a galvanic cell. Both Mg and ZVI have been combined with various catalytic metals to produce reductive bimetal systems that have treated effectively halogenated compounds and nitro-based explosives (Morales et al, 2002;DeVor et al, 2009;Begum and Gautam, 2011;Koutsospyros et al, 2012;Liu et al, 2015).…”

Mineralization of N‐Methyl‐2‐Pyrrolidone by UV‐Assisted Advanced Fenton Process in a Three‐Phase Fluidized Bed Reactor

“…Then, the Fenton reaction (Equation ) occurs and produces hydroxyl radicals to attack the contaminants, with Fe 2+ being oxidized to Fe 3+ . Fe 2+ can be regenerated on the surface of Fe 0 (Equation ) or with the assistance of UV light (Equation ): …”