Mössbauer spectroscopy for the characterization of soils used as catalysts

Moya, Sergio A.; Flores, A.; Escudey, Mauricio; Venegas, Ricardo; Castello, Gianrico; Latorre, Ramón

doi:10.1007/bf02398204

Cited by 3 publications

(6 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Transformations being with simple dehydration (105-220 ºC), progress to dehydrogenation and decarboxylation of organic matter (220-280 ºC), are followed by dehydroxylation of allophane andimogolite (280-420 ºC), and finally reach total organic matter oxidation (500 ºC). These expected changes have been corroborated by studies with different soil samples(Escudey and Moya 1989;Moya et al 1991a;Pizarro et al 2005).…”

supporting

confidence: 60%

“…As detailed in Table 1, the most abundant applications are related to the Fenton and Fenton-like reaction processes. Previously, Escudey and Moya (1989), Moya et al (1991a), and Pizarro et al (2005) reported the application of Chilean volcanic soils as WGS reaction catalysts, which will be further reviewed herein.…”

Section: Technological Applications Of Natural Iron Oxidesmentioning

confidence: 99%

“…Our group previously studied volcanic soil samples (Moya et al 1991a;Pizarro et al 2005). Heating temperature affects catalyst performance significantly but differently for each soil.…”

Section: Volcanic Soils As Catalysts For the Water Gas Shift Reactionmentioning

confidence: 99%

“…B-horizon) from southern Chile, specifically from Collipulli (Ultisol, 30º54'S 72º25'W), Osorno (Andisol, 40º33'S 73º4'W) and San Patricio (Andisol, 38º39'S 72º78'W)(Escudey and Moya, 1989;Moya et al 1991a;Pizarro et al 2005;Pizarro et al 2017). Iron-bearing minerals from soils developing on volcanic materials from Southern Chile Thermal pre-treatment (heating up to 600 ºC) of soil samples was applied for two purposes: destruction of the organic matter, which exposed active catalyticsites of iron oxides; and crystallization of the inorganic layer to alter the silicon-, aluminium-and ironoxide mineral phase.…”

mentioning

confidence: 99%

See 3 more Smart Citations

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.

View full text Add to dashboard Cite

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.

show abstract

supporting

confidence: 60%

Section: Technological Applications Of Natural Iron Oxidesmentioning

confidence: 99%

“…Our group previously studied volcanic soil samples (Moya et al 1991a;Pizarro et al 2005). Heating temperature affects catalyst performance significantly but differently for each soil.…”

Section: Volcanic Soils As Catalysts For the Water Gas Shift Reactionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

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.

View full text Add to dashboard Cite

show abstract

“…It has been considered an increasing interest to know about their potential applicability, specifically of their clay fraction, as inexpensive heterogeneous catalysts, for different reactions of environmental and industrial uses, as water gas shift, Fenton and Fenton-like reactions [5,6]. Ultisols are particularly rich in magnetic iron oxides, which are mainly found in their sand fractions.…”

Section: Introductionmentioning

confidence: 99%

Magnetic minerals from volcanic Ultisols as heterogeneous Fenton catalysts

et al. 2009

View full text Add to dashboard Cite

This study was devoted to the evaluation of the effectiveness of Fenton catalysts, based on magnetically-concentrated portions of iron oxide-rich sand fractions from two magnetic Ultisols, derived from volcanic materials of southern Chile. The samples were labeled according to the municipality where the sample sites are geographically located, namely Metrenco and Collipulli, and were characterized with Mössbauer spectroscopy at 298 K and saturation magnetization (σ ) measurements. Mössbauer data revealed a complex magnetic hyperfine structure for these magnetic portions from both soil-sand materials, suggesting relatively complex mineral assemblages. The monitored rate of H 2 O 2 decomposition via heterogeneous Fenton reaction revealed that materials from the Collipulli soil are more efficient Fenton catalyst than are those from the Metrenco soil. The reasons for these differences are from now on being explored on basis of a more detailed chemical investigation of these samples.

show abstract