Oxidation of 4-chlorophenol in a heterogeneous zero valent iron/H2O2 Fenton-like system: Kinetic, pathway and effect factors

Zhou, Tao; Li, Yaozhong; Ji, Jing; Wong, Fook-Sin; Lü, Xiaohua

doi:10.1016/j.seppur.2008.03.008

Cited by 239 publications

(136 citation statements)

References 19 publications

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“…The two-step reaction is reminiscent of a previous study using a heterogeneous zero-valent iron system for 4-CP degradation. 27 We observed slow initial changes in 4-CP, H + and Fe ion concentrations up to 2 h, but at the later stage, where Fe ion release into the homogeneous phase is increased, 4-CP degradation increased in parallel. This may suggest that the dissolution of Fe ions was auto-catalytic, with the H + released by 4-CP degradation accelerated Fe dissolution and further 4-CP degradation.…”

mentioning

confidence: 59%

“…The two-step reaction is reminiscent of a previous study using a heterogeneous zero-valent iron system for 4-CP degradation. 27 We observed slow initial changes in 4- 25,45 addressing the pH influence we note that manipulating the initial pH instead of buffering the solutions may not be sufficient to prevent leaching because solutions would gradually become more acidic; HCl and organic acids are the reaction intermediates/products of 4-CP degradation. 46 …”

Section: Methodsmentioning

confidence: 82%

“…This "homogeneous or heterogeneous problem" is by no means unique in catalysis 10, 11 and is often not straightforward to address. [22][23][24][25][26][27] while some work assumed that the reactions proceeded through a heterogeneous route. [28][29][30][31][32][33] Approaches that have been used to ascertain the presence of heterogeneous catalytic routes have included: (i) re-using filtered solutions and checking for organic degradation; 17,21,34 (ii) buffering solutions at alkaline/near-neutral pH to prevent metal ions leaching; 19, 20 (iii) comparing organic degradation kinetics in homogeneous and heterogeneous catalytic systems; 35 and (iv)…”

Section: Introductionmentioning

confidence: 99%

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Fenton-Like Oxidation of 4-Chlorophenol: Homogeneous or Heterogeneous?

Kuan

Chang

Schroeder

2015

Ind. Eng. Chem. Res.

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Heterogeneous Fenton-like catalysts have received considerable research attention because they could potentially be attractive for oxidative removal of organic contaminants from tertiary wastewater.However, process design is still hampered by insufficient understanding of the chemical pathways involved, and especially whether oxidation activity stems from heterogeneous surface chemistry or minute concentrations of dissolved metal ions in the homogeneous phase. Using inductively coupled plasma-optical emission spectroscopy (ICP-OES) in combination with pH monitoring and ultravioletvisible spectroscopy (UV-Vis) we have monitored the degradation of 4-chlorophenol (4-CP) over two Fenton-like heterogeneous systems, namely FeOx supported on TiO2 and CuFe2O4. We show conclusively that these systems proceed predominantly through a homogeneous route via dissolved metal ions from the solid phase catalysts. Control experiments with homogeneous Fe 3+ or Cu 2+ systems reveal that even minute concentrations ( M/sub-ppm) of dissolved metal ions leached from the solid phases account for the observed 4-CP degradation rates in the heterogeneous systems. ICP-OES revealed that metal leaching was time-dependent and variable because of pH variations associated with changing acid release rates. Buffering solutions at pH 7.4 suppressed metal leaching (and hence 4-CP degradation) in the FeOx/TiO2 system, but not in others. For example, pH buffering did not entirely suppress metal leaching from CuFe2O4, for which 4-CP degradation was retained through small concentrations of Fe and Cu ions in solution. Our results highlight the importance of careful monitoring of metal content in the aqueous phase, certainly with analytical sensitivity below ppm concentrations of the dissolved metals, and also the crucial influence of time-dependent pH variations on the reaction process. Recyclability of catalysts, pH buffering of solutions or monitoring of metal content in the solid phase by less sensitive analytical methods, e.g., chemical analysis, gravimetry, X-ray fluorescence, or energy dispersive X-ray analysis in electron microscopes, cannot exclude the homogeneous Fenton route in the presence of solid catalysts. 2Keywords CuFe2O4, leaching, homogeneous, heterogeneous, catalysis IntroductionFenton's reaction is an efficient way for treating organic contaminants, e.g. for soil remediation, 1 oil spill clean-up, 2 and industrial wastewater treatment. 3 Through the addition of Fe 2+ , H2O2 and acid to wastewater streams OH radicals ( • OH) can be generated through the oxidation of Fe 2+ (Fenton's reaction, eq. 1).• OH is the active species that degrades organic contaminants. Fenton's reaction proceeds optimally around pH 3, thus wastewater streams need to be acidified. 5 Subsequent neutralisation leads to Fe(OH)3 precipitates as a sludge, requiring an additional separation step. 6 This complexity of the homogeneous Fenton route motivated investigations of heterogeneous Fenton-like systems, seeking to localise the Fenton process at the su...

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mentioning

confidence: 59%

Section: Methodsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Fenton-Like Oxidation of 4-Chlorophenol: Homogeneous or Heterogeneous?

Kuan

Chang

Schroeder

2015

Ind. Eng. Chem. Res.

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“…The efficiency of CWPO with iron minerals has been found to depend greatly on the dissolution of iron from the solid [40,43,44,48,54]. Therefore, the iron mineral is used as dissolved iron source and the oxidation proceeds mostly via homogeneous Fenton.…”

Section: Magnetic Natural Mineralsmentioning

confidence: 99%

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

Muñoz

Pedro

Casas

et al. 2015

Applied Catalysis B: Environmental

666

274

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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: AbstractThis study presents a critical review on the application of magnetite-based catalysts to industrial wastewater decontamination by heterogeneous Fenton oxidation. The use of magnetic materials in this field started only around 2008 and continues growing increasingly year by year. The potential of these materials derives from their higher ability for degradation of recalcitrant pollutants compared to the conventional iron-supported catalysts due to the presence of both Fe(II) and Fe(III) species. In addition, their magnetic properties allow their easy, fast and inexpensive separation from the reaction medium. The magnetic materials applied up to now can be classified in three general groups: magnetic natural minerals, in-situ-produced magnetic materials and ferromagnetic nanoparticles. A survey of the catalysts investigated so far is presented paying attention to their nature and competitive features in terms of activity and durability.2

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“…한편, 최근 연구에서는 영가철의 산화적 처리기법 을 이용해서 유해물질을 처리한 연구들이 보고되고 있는 데 (Joo et al, 2004;Zhou et al, 2008) (Buxton et al, 1988;Joo et al, 2004;Roy et al, 2003 (Keenan and Sedlak, 2008a, b;Lee and Sedlak, 2008). Hatchard and Parker, 1956).…”

Section: 서 론unclassified

Oxidative Degradation of Phenol Using Zero-Valent Iron-Based Fenton-Like Systems

Kim¹,

Lee²,

Kim³

et al. 2013

Journal of Soil and Groundwater Environment

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For the last couple of decades, the Fenton (-like) systems have been extensively studied for oxidation of organic contaminants in water. Recently, zero-valent iron (ZVI) has received attention as a Fenton catalyst as well as a reducing agent capable of producing reactive oxidants from oxygen. In this study, the ZVI-based Fenton reaction was assessed for the oxidative degradation of phenol using ZVI/O 2 , ZVI/H 2 O 2 , ZVI/Oxalate/O 2 and hv/ZVI/Oxalate/O 2 systems. Reaction parameters such as pH and reagent dose (e.g., ZVI, H 2 O 2 , and oxalate) were examined. In the presence of oxalate (ZVI/ Oxalate/O 2 and hv/ZVI/Oxalate/O 2 systems), the degradation of phenol was greatly enhanced at neutral pH values. It was found that ZVI accelerates the Fenton reaction by reducing Fe(III) into Fe(II). The conversion of Fe(III) into Fe(II) by ZVI was more stimulated at acidic pH than at near-neutral pH values.

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Oxidation of 4-chlorophenol in a heterogeneous zero valent iron/H2O2 Fenton-like system: Kinetic, pathway and effect factors

Cited by 239 publications

References 19 publications

Fenton-Like Oxidation of 4-Chlorophenol: Homogeneous or Heterogeneous?

Fenton-Like Oxidation of 4-Chlorophenol: Homogeneous or Heterogeneous?

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

Oxidative Degradation of Phenol Using Zero-Valent Iron-Based Fenton-Like Systems

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