Synthesis of a Fe/AC Fenton‐like catalyst and heterogeneous catalysis in decolorization of Sunset Yellow by pulsed high‐voltage discharge

Abstract

BACKGROUND A new Fe/AC heterogeneous Fenton‐like catalyst was prepared using a dipping–sintering method. The prepared catalyst was characterized by X‐ray diffraction and scanning electron microscopy. The decolorization of Sunset Yellow was conducted in a self‐designed pulsed high‐voltage discharge system by the catalysis of the prepared heterogeneous catalyst. Effects of preparation conditions of catalyst (carrier material, sintering temperature and dipping time) and operating conditions (catalyst dosage, pH and treatment method) on decolorization efficiency were investigated. RESULTS Spherical activated carbon (AC) was selected as the carrier material and the optimal dipping time and sintering temperature were 8 h and 350 °C, respectively. The efficiency of decolorization of Sunset Yellow was above 90% after 30 min of a pulsed high‐voltage discharge process with 5 g heterogeneous catalyst and at pH 2.00. The utilization of copper mesh not only enhanced the decolorization of Sunset Yellow but also facilitated the reusability of the prepared heterogeneous catalyst. The efficiency of decolorization of Sunset Yellow with prepared Fe/AC heterogeneous Fenton‐like catalyst (5 g) was even a little higher than that with homogeneous catalyst (1.635 mmol L−1 Fe2+). The decolorization efficiency remained above 90% after ten recycles of the catalyst, indicating that the prepared heterogeneous catalyst has good stability and reusability. In addition, a possible catalytic mechanism for the decolorization reaction in a pulsed high‐voltage discharge system with prepared Fe/AC heterogeneous Fenton‐like catalyst was proposed by determination of H2O2 and ·OH concentrations in deionized water. CONCLUSIONS The prepared Fe/AC heterogeneous Fenton‐like catalyst efficiently degrades Sunset Yellow wastewater in a pulsed high‐voltage discharge system. © 2016 Society of Chemical Industry

Hybrid electric discharge plasma technologies for water decontamination: a short review

“…Fe-based ions and compounds such as Fe 2+ or Fe 3+ [33], Fe/AC [34], pyrite (FeS 2 ) [35], maghemite (γ-Fe 2 O 3 ) [36], magnetite (Fe 3 O 4 ) [37], and so on are the most frequently used catalysts in plasma Fenton-like reactions. Figure 2 shows the pathways of homogeneous or heterogeneous catalysis of H 2 O 2 into •OH by Fe-based catalysts (R1), different from the homogeneous catalysis process, the interfacial reactions are very important for the decomposition of H 2 O 2 into their reactive species (•OH, HO 2 •, etc) and the degradation of pollutant on the surface of heterogeneous Fe-based catalysts.…”

“…Figure 2 shows the pathways of homogeneous or heterogeneous catalysis of H 2 O 2 into •OH by Fe-based catalysts (R1), different from the homogeneous catalysis process, the interfacial reactions are very important for the decomposition of H 2 O 2 into their reactive species (•OH, HO 2 •, etc) and the degradation of pollutant on the surface of heterogeneous Fe-based catalysts. Although homogeneous catalysis of H 2 O 2 by Fe 2+ generated more •OH than the heterogeneous one [34], possibly due to less mass transfer limits of homogeneous catalysis, an unsatisfactory consumption reaction of •OH by Fe 2+ also happens (R2); however, heterogeneous catalysis of H 2 O 2 helps to reduce the consumption of •OH by Fe 2+ . Moreover, it is believed that a cycling of Fe 3+ /Fe 2+ can be formed through the reduction of Fe 3+ on the catalyst surface by aqueous electrons (e aq -), which can alleviate the excessive iron sludge production in conventional Fenton oxidation systems, and heterogeneous catalysts also lead to less leakage of metal ions, which are more friendly to the environment.…”