Application of a supported iron oxyhydroxide catalyst in oxidation of benzoic acid by hydrogen peroxide

Chou, Shanshan; Huang, Chihpin

doi:10.1016/s0045-6535(98)00474-3

Cited by 140 publications

(77 citation statements)

References 17 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- 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: 90%

“…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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Section: Methodsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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

Kuan

Chang

Schroeder

2015

Ind. Eng. Chem. Res.

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“…Some of the irons containing solids that were investigated were goethite, hematite, clay minerals, iron hydroxide and iron supported on silica and on alumina. [4][5][6][7][8][9] However, these iron promoters showed low activities or strong iron leaching due to low pH which produced mainly homogeneous reactions.…”

Section: Use Of Iron Phases and Heterogeneous Fenton Systemsmentioning

confidence: 99%

Iron: a versatile element to produce materials for environmental applications

Teixeira¹,

Tristão²,

Araújo³

et al. 2012

J. Braz. Chem. Soc.

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Ferro é um elemento versátil que forma várias fases com diferentes estados de oxidação e estruturas, tais como Fe 0 , FeO, Fe 3 O 4 , γ-Fe 2 O 3 , α-Fe 2 O 3 e FeOOH. Todas estas fases têm propriedades físico-químicas únicas que podem ser usadas para diferentes aplicações. Neste trabalho, descreve-se o uso de diferentes compostos de ferro, sintéticos e também naturais ou de rejeitos, em aplicações ambientais e tecnológicas. Duas áreas principais de pesquisa são descritas. A primeira é relacionada às estratégias para aumentar a reatividade de fases de ferro pela formação de compósitos Fe 0 /Fe óxido e pela introdução de novos metais na estrutura de óxidos de ferro para promover novas reações superficiais. A segunda área de pesquisa é o uso das propriedades magnéticas de algumas fases de ferro para produzir materiais magnéticos versáteis com aplicações focadas em adsorção, catálise e emulsões.Iron is a versatile element forming several phases with different oxidation states and structures, such as Fe 0 , FeO, Fe 3 O 4 , γ-Fe 2 O 3 , α-Fe 2 O 3 and FeOOH. All these phases have unique physicochemical properties which can be used for different applications. In this work, it is described the use of different iron compounds, synthetic and also from natural and waste sources, in environmental and technological applications. Two main research areas are described. The first one is related to strategies to increase the reactivity of Fe phases, mainly by the formation of Fe 0 /iron oxide composites and by the introduction of new metals in the iron oxide structure to promote new surface reactions. The second area is the use of the magnetic properties of some iron phases to produce versatile magnetic materials with focus in adsorption, catalysis and emulsions.

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“…A number of researchers (Valentine and Wang, 1998;Miller and Valentine, 1999) with attempt to minimize the leaching of iron ion focused on the efficiency of heterogeneous catalysis for pollutant oxidation. Recently, considering the practical application of the oxidation process, supported iron oxides or granular size solid catalysts, such as graphite and activated carbon, were also studied for their catalytic characteristics (Lucking et al, 1998;Chou and Huang, 1999). In addition, the potential for applying H 2 O 2 to Fenton-like water treatment is primarily restricted to the supply and stability of H 2 O 2 .…”

Section: Introductionmentioning

confidence: 99%

Catalytic decomposition of hydrogen peroxide and 4-chlorophenol in the presence of modified activated carbons

et al. 2003

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The objective of this research was to examine the heterogeneous catalytic decomposition of H 2 O 2 and 4-chlorophenol (4-CP) in the presence of activated carbons modified with chemical pretreatments. The decomposition of H 2 O 2 was suppressed significantly by the change of surface properties including the decreased pH pzc modified with oxidizing agent and the reduced active sites occupied by the adsorption of 4-CP. The apparent reaction rate of H 2 O 2 decomposition was dominated by the intrinsic reaction rates on the surface of activated carbon rather than the mass transfer rate of H 2 O 2 to the solid surface. By the detection of chloride ion in suspension, the reduction of 4-CP was not only attributed to the advanced adsorption but also the degradation of 4-CP. The catalytic activity toward 4-CP for the activated carbon followed the inverse sequence of the activity toward H 2 O 2 , suggesting that acidic surface functional group could retard the H 2 O 2 loss and reduce the effect of surface scavenging resulting in the increase of the 4-CP degradation efficiency. Few effective radicals were expected to react with 4-CP for the strong effect of surface scavenging, which could explain why the degradation rate of 4-CP observed in this study was so slow and the dechlorination efficiency was independent of the 4-CP concentration in aqueous phase. Results show that the combination of H 2 O 2 and granular activated carbon (GAC) did increase the total removal of 4-CP than that by single GAC adsorption.

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Application of a supported iron oxyhydroxide catalyst in oxidation of benzoic acid by hydrogen peroxide

Cited by 140 publications

References 17 publications

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

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

Iron: a versatile element to produce materials for environmental applications

Catalytic decomposition of hydrogen peroxide and 4-chlorophenol in the presence of modified activated carbons

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