Magnetic minerals from volcanic Ultisols as heterogeneous Fenton catalysts

Aravena, S.; Pizarro, Carmen; Rubio, Marı́a A.; Cavalcante, Luís Carlos Duarte; Garg, V. K.; Pereira, Maria Cecília; Fabris, José Domingos

doi:10.1007/978-3-642-10764-1_7

Cited by 2 publications

(3 citation statements)

References 6 publications

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“…activity can be evaluated through quantification of HOOH decomposition via O 2 volume measurement on a gas-tight system (3.5 mol L -1 hydrogen peroxide on a volumetric gas system at pH 5.0 at 21 ºC using 15 mg of the respective catalyst) as Room Temperature 57 Fe-Mössbauer spectra for the magnetic separates from (a) Collipulli and (b) Metrenco sand-size soil samples, respectively. (Adapted fromAravena et al 2010) described byAravena et al (2010). In this work the decomposition kinetics of HOOH appeared to be of pseudo zeroth order regardless of the catalyst type.The reaction rate constant for HOOH decomposition when employing Collipulli and Metrenco magnetic separates were 40.0 x10 -5 and 8.0 x10 -5 M min -1 , respectively.…”

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confidence: 61%

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Application in heterogeneous catalysis

Pizarro

Escudey

Gacitúa

et al. 2018

J. Soil Sci. Plant Nutr.

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Chilean soils derived from volcanic ashes are a natural source of iron oxides. Due to their properties, mineralogy, and surface characteristics, iron oxides from Chilean soils are potential candidates for technological applications such as heterogeneous catalysis. However, before a direct application in catalysis, pre-treatment methods are necessary to concentrate iron oxides from bulk volcanic soils. Here, we provide a comprehensive review of pre-treatment strategies for iron oxide concentration including physical separation and selective chemical dissolutive methods for application in catalytic processes, such as the water gas shift (WGS) and Fenton reactions. For preparation of WGS catalyst from volcanic soils, thermal treatment has been demonstrated to be effective, yielding enhanced results for Andisols compared to Ultisols. Based on mineralogical characterisation, it seems that WGS reaction efficiency depends on mineralogical phase shift and the changes of Fe 2+ /Fe 3+ ratio, produced through heating. In addition, Ultisols have shown as efficient catalysts in Fenton and Fenton-like processes, after application of physical and chemical pre-treatments to different size-fractions of the soil sample, improving the yield performance of catalysts. Magnetic separates from the Ultisol sand fraction (compared to the silt+clay fractions) demonstrate the best catalytic performance as Fenton reagent due to their natural magnetite and titanomagnetite content. Application of NaOH selective dissolutive treatment to silt+clay fraction of volcanic soils also produces Fenton and Fenton-like catalyst with improved performance. Our review indicates that catalytic performance can be explained not only by the iron oxide mineral content but also by their characteristics and magnetic properties.The application of the appropriate physical and chemical pre-treatment methods can modulate and enhance the catalytic capabilities of iron oxides from volcanic soils.

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confidence: 61%

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Application in heterogeneous catalysis

Pizarro

Escudey

Gacitúa

et al. 2018

J. Soil Sci. Plant Nutr.

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“…The Fenton activity was evaluated through the decomposition of 30% p/p hydrogen peroxide, by measuring the evolving gaseous O 2 , in a volumetric gas system, at pH 5.0, using 15 mg of the solid sample, as catalyst [5].…”

Section: Catalytic Testsmentioning

confidence: 99%

“…Some related studies dealing with natural iron oxides as catalysts for heterogeneous Fenton and Fenton-like reactions have been recently reported [4,5]. The Fenton reaction (1) is based on the reaction of Fe 2+ and H 2 O 2 to produce highly reactive intermediate species that induce the generation of hydroxyl radical, according to the process [6]:…”

Section: Introductionmentioning

confidence: 99%

Preparative treatment with NaOH to selectively concentrate iron oxides of a Chilean volcanic soil material to produce effective heterogeneous Fenton catalyst

Manzo¹,

Pizarro²,

Rubio³

et al. 2011

Hyperfine Interact

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A Chilean volcanic Ultisol material was first size-fractionated so as to obtain the fraction with mean particle sizes φ < 53 μm. This sample was then sequentially treated three or five times with 5 mol L −1 NaOH, in an attempt to evaluate the effectiveness of the selective chemical dissolution to concentrate iron oxides, as a preparation procedure before using the materials as heterogeneous Fenton catalysts. The effects of those treatments on the iron oxides mineralogy were monitored with Mössbauer spectroscopy. The NaOH-treated samples were tested as catalysts towards the H 2 O 2 decomposition. Three or five sequential NaOH treatments were found to be comparably effective, by concentrating nearly the same proportion of iron oxides in the remaining solid phase (25.1 ± 0.4 and 23.3 ± 0.2 mass%, V. Manzo et al. respectively). 298 K-Mössbauer patterns were similar for both samples, with a central (super)paramagnetic Fe 3+ doublet and a broad sextet, assignable to several closely coexisting magnetically ordered forms of iron oxides. Despite of this nearly similar effect of the two treatments, the Ultisol material treated three times with NaOH presents higher heterogeneous catalytic efficiency and is more suitable to decompose H 2 O 2 than that with five treatments.

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Magnetic minerals from volcanic Ultisols as heterogeneous Fenton catalysts

Cited by 2 publications

References 6 publications

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Application in heterogeneous catalysis

Iron-bearing minerals from soils developing on volcanic materials from Southern Chile: Application in heterogeneous catalysis

Preparative treatment with NaOH to selectively concentrate iron oxides of a Chilean volcanic soil material to produce effective heterogeneous Fenton catalyst

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