888 research outputs found

    CO2-assisted hydrolytic hydrogenation of cellulose and cellulose-based waste into sorbitol over commercial Ru/C

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    A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant. Under these conditions, cellulose was first hydrolysed to glucose by reversibly formed carbonic acid in water and then instantaneously hydrogenated on Ru/C. By tuning the reaction parameters, such as temperature, time and the relative pressure of CO2 and hydrogen gas, cellulose was fully converted at 220 & DEG;C in 18 h under 30 and 40 bar of H-2 and CO2, respectively, with a sorbitol yield of 81%. Blank experiments revealed that without a catalyst and hydrogen, the reaction exhibited <5% conversion and glucose was the only detected product when the reaction was performed under CO2 pressure. XRD measurements on CO2-treated cellulose surprisingly revealed no noticeable changes in the crystallinity index (<10% with respect to microcrystalline cellulose), suggesting that hydrolytic hydrogenation took place on crystalline, not amorphous, cellulose. Furthermore, not only several cellulosic feedstocks, including filter paper, cotton wool, and cotton fiber, but also typical cellulose-based wastes such as a cardboard pizza box were also tested and under the optimized conditions sorbitol was obtained with yields ranging from 56% up to 72% in all cases. No less significant was the Ru/C catalyst stability, which could be recycled at least six times without any noticeable activity loss

    A year-round measurement of water-soluble trace and rare earth elements in arctic aerosol: Possible inorganic tracers of specific events

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    This study presents the year-round variability of the water-soluble fraction of trace elements (wsTE) and rare earth elements (wsREE) among size segregated airborne particulate matter samples collected at Ny-Ã… lesund in the Svalbard Archipelago from 26 February 2018 to 26 February 2019. Six different aerosol dimensional fractions were collected using a multi-stage Andersen impactor to better understand local and global circulation with the aim of disentangling the source of inorganic tracers from specific natural or anthropogenic sources. The wsTE and wsREE content, especially in the finest fractions in remote areas, is primarily related to long-range transport and it gives valuable information on (1) the global circulation, (2) the natural sources and (3) the contribution of human activities to aerosol composition. A Factor Analysis was applied to the dataset, including levoglucosan and methanesulfonic acid (MSA), to assess the possibility of using certain inorganic tracers as indicators of specific transport events or circulation regimes. We also investigate back-trajectories to determine potential source areas

    Fragrance materials (FMs) affect the larval development of the copepod Acartia tonsa: An emerging issue for marine ecosystems

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    Fragrance materials (FMs) are used in a variety of detergents and cosmetics, including household and personal care products. Despite their widespread use and the growing evidence of their occurrence in surface waters worldwide, very little is known about their toxicity towards marine species, including a key component of the marine food webs such as copepods. Thus, we investigated the toxicity of six of the more long-lasting and stable commercial fragrances, including Amyl Salicylate (AMY), Oranger Crystals (ORA), Hexyl Salicylate (HEX), Ambrofix (AMB), Peonile (PEO), and Benzyl Salicylate (BZS), to assess their ability to impair the larval development of the calanoid copepod Acartia tonsa. FMs inhibited the development of A. tonsa significantly at concentrations by far lower than the effect-concentrations reported in the literature for aquatic species. The more toxic FMs were HEX (EC50 = 57 ng L−1), AMY (EC50 = 131 ng L−1) and ORA (EC50 = 766 ng L−1), while the other three compounds exerted toxic effects at concentrations higher than 1000 ng L−1 (LOEC at 1000 ng L−1 for PEO and BZS, and at 10,000 ng L−1 for AMB). Early life-stage mortality was unaffected by FMs at all the tested concentrations. A comparison with water concentrations of FMs reported in the literature confirmed that FMs, especially HEX and AMY, may act as contaminants of potential concern in many aquatic habitats, including urban areas and remote and polar environments

    The Great Acceleration of fragrances and PAHs archived in an ice core from Elbrus, Caucasus

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    The Great Acceleration of the anthropogenic impact on the Earth system is marked by the ubiquitous distribution of anthropogenic materials throughout the global environment, including technofossils, radionuclides and the exponential increases of methane and carbon dioxide concentrations. However, personal care products as direct tracers of human domestic habits are often overlooked. Here, we present the first research combining fragrances, as novel personal care products, and polycyclic aromatic hydrocarbons (PAHs) as combustion and industrial markers, across the onset of the Great Acceleration in the Elbrus, Caucasus, ice core. This archive extends from the 1930s to 2005, spanning the profound changes in the relationship between humans and the environment during the twentieth century. Concentrations of both fragrances and PAHs rose throughout the considered period, reflecting the development of the Anthropocene. However, within this rising trend, remarkable decreases of the tracers track the major socioeconomic crises that occurred in Eastern Europe during the second half of the twentieth century

    Impact of sound attenuation on ultrasound-driven yield improvements during olive oil extraction

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    High frequency ultrasound can enhance olive oil extractability industrially. However, the ultrasound attenuation phenomena and their implications on extractability, are not well understood. This work aims at evaluating the ultrasound attenuation effects on the oil extraction efficiency, while providing deeper insights into the physics behind the ultrasound extraction in a heterogeneous medium. Olives were collected and processed both in Italy and Uruguay during their respective harvest seasons. Sound pressure distribution was characterized in a high frequency ultrasound reactor, carrying 3 kg of water or paste, by using an indirect contact hydrophone device at 0.4 MHz or 2 MHz. A through-transmission ultrasonic technique was applied to determine attenuation profiles and coefficients in paste at the central frequency of each transducer, with various paste to water ratios and reactor sizes. Other ultrasound improvements on extractability were evaluated including reduction of malaxation time (10, 30 min), sonication time (2.5, 5 min) and power level (174, 280 W) without water addition and in a reactor with a 14.5 cm transducer to wall distance. However, no sound pressure levels in paste were detectable beyond 9 cm from the transducer at both frequencies. Among the various effects evaluated, an emission frequency of 0.4 MHz better improved extractability compared to 2 MHz. The attenuation profiles corroborated these findings with attenuation coefficients of 3.9 and 5.3 dB/cm measured near the respective frequencies. Improvements in oil extractability due to increasing sonication time and power level were significant (p < 0.05) also when sonicating beyond 14.5 cm and without water addition. Oil extractability improvements were observed even when sound pressure was undetectable beyond 9 cm from the transducer, suggesting that the standing wave oil trapping effect is not the governing mechanism for separation in high attenuation media for large scale systems

    The Occurrence of Glyphosate and its Degradation Products in the Urban Stormwater: A Short Review

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    Due to urbanization and industrialization, water pollution is now one of the major environmental challenges of the twenty-first century. Considering the increasing of agricultural and non-agricultural settings in the last decades, the investigation of the relationship between such pesticides and urban stormwater is critical to understand how urban, residential, and industrialized areas can affect environmental safety. Recently, scientific interest has grown in stormwater chemical characterization with the aim to define its impacts in the environment and possibly to make it potable water. In this context, glyphosate, glufosinate, and their degradation products have been identified as the key knowledge gap for the chemical characterization of stormwater. Research investments are needed for a better understanding of the highly polar pesticides to estimate their load, source, and dispersion of urban runoff due to residential use of herbicides. Furthermore, a more comprehensive study of wet and dry deposition and spray drift should be considered for a correct evaluation of source apportionment

    Microplastic accumulation in benthic invertebrates in Terra Nova Bay (Ross Sea, Antarctica)

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    Microplastic contamination of the benthic invertebrate fauna in Terra Nova Bay (Ross Sea, Antarctica) was determined. Twelve macrobenthic species, characterized by different feeding strategies, were selected at 3 sampling sites at increasing distance from the Italian Scientific Base (Mario Zucchelli, Camp Icarus, Adelie Cove). The 83% of the analyzed macrobenthic species contained microplastics (0.01–3.29 items mg−1). The size of the particles, measured by Feret diameter, ranged from 33 to 1000 µm with the highest relative abundance between 50 and 100 µm. Filter-feeders and grazers displayed values of microplastic contamination from 3 to 5 times higher than omnivores and predators, leading to the hypothesis that there is no evident bioaccumulation through the food web. The prevalent polymers identified by micro-FTIR were nylon (86%) and polyethylene (5%); other polymers identified in Antarctic benthos were polytetrafluoroethylene, polyoxymethylene, phenolic resin, polypropylene, polystyrene resin and XT polymer
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