Fe speciation in Iron modified natural zeolites as sustainable environmental catalysts

Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe2+ or Fe3+ salts (Fe2+ZP and Fe3+ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3H6. Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species’ nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+/Fe3+ extra-framework sites and FexOy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ZP showed a higher intensity of nitrosonium (NO+) species, without a correlation to NO storage and conversion, pointing to the reactivity of small FexOy aggregates in providing oxygen atoms for the NO to NO+ reaction. The same sites are proposed to be responsible for the higher production of CO2 observed on this sample, and thus to be detrimental to the activity in NO SCR

Long-term impacts of wastewater irrigation on Cuban soils

The disposal of wastewater, known as vinasse, from rhe sugarcane (Saccharum officinarum L.) industry creates environmental problems. Agriculture can offer a potential solution to these problems by using organic residues as substitutes for chemical fertilizers. This study was conducted in Ultisol profiles from Cuba irrigated with vinasse for 40 yr. The effects of this application on physicochemical and mineralogical properties of soils were investigated. Soils fertilized with traditional inorganic fertilizers were used for comparison. Fertilization with the wastewater caused a decrease of soil pH to a depth of 100 cm. There was an increase, however, in electrical conductivity because of the large concentration of K in the wastewater. The amendment also increased the organic matter content throughout the profile. Vinasse application yielded the intercalation of some compounds in the clay mineral smectite. The formation of organo-mineral complexes produced little change in the particle size distribution, but an increase in the poorly crystalline Fe oxyhydroxides in the upper horizon up to 22%, and the crystallinity of Fe oxyhydroxide in the soil decreased substantially. This was probably due to dissolution and reprecipitation of these oxides by the acid pH of the wastewater. Total and poorly crystalline Mn contents also decreased. The amendment material increased the mobility of metals because of the formation of water-soluble complexes with organic ligands. The results showed that long-term wastewater irrigation could be of agricultural interest due mainly to its organic matter concentration, but micronutrient concentrations in the upper horizons were negatively affected because complexing of metals favored their transport throughout the soil profile, which may eventually lead to deterioration of groundwater quality and micronutrient deficiency.The financial support of the Junta de Andalucía through the projects PAI RMN 166 and Exp. 92162/1 is greatly acknowledged.Peer Reviewe

Efficient particle bombardment-mediated transformation of Cuban soybean (INCASoy-36) using glyphosate as a selective agent.

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Organic and inorganic contamination impacts on metabolic capacities in American and European yellow eels

International audienc