1,721,028 research outputs found
Nanoporous Materials as H2S Adsorbents for Biogas Purification: a Review
No full textBiogas is one of the most promising renewable sources of energy. However, it is also a gas mixture containing acidic gases, such as H2S, useless for energetic purposes, environmentally harmful and damaging for energy conversion devices. This review focuses on nanoporous materials as adsorbents of H2S for biogas purification processes. Cation-exchanged zeolites and impregnated activated carbons have been thoroughly studied since many years for this application, providing good results, in particular for what concerns activated carbons, despite having a limited regenerability. Amino-functionalized ordered mesoporous silicas produced very interesting results, both in terms of adsorption performances and regeneration capacity, but they are largely untested in large-scale “real-life” applications, and deserve further investigations, in particular for H2S and CO2 discrimination. On the contrary, despite reporting very good results, there are only few papers dealing with H2S adsorption on nanoporous metal organic frameworks
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Thermo-mechanical behaviour of hemp fibers-reinforced gypsum plasters
No full textDue to the large latent heat related to dehydration into hemihydrate and anhydrite, gypsum is largely used to make firebreak systems. During a fire exposure, the dehydration can induce cracks inside the panels, since the loss of bound-water molecules leads to a large thermal shrinkage. In this study, hemp fibers were added into the plaster, acting as thermo-mechanical reinforcement of the gypsum panels and hindering the cracks formation. The effect of hemp fibers on the thermal behavior of gypsum panels was studied in terms of thermo-mechanical properties in isothermal conditions. Change in chemical composition and morphology of the gypsum matrix after the thermomechanical test were analysed by thermogravimetry (TGA), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Hemp fibers, even at high temperatures, preserved their “bridge action” between the fracture surfaces, increasing the tenacity of plaster and preventing its fragile collaps
Evaluation of an intermediate-silica sedimentary chabazite as exchanger for potentially radioactive cations
No full textComparative ion-exchange characterization of zeolitic and clayey materials for pedotechnical applications—Part 1: interaction with noxious cations
No full textABSTRACT
With the purpose to set up a convenient strategy to rehabilitate degraded soils by recovering their functionality, the possibility of using zeolitized tuff as inorganic ion-exchanger components of organomineral aggregates, in place of the naturally occurring clay materials was estimated. Accordingly, after the evaluation of a suitable method for measuring the cation exchange capacity of both materials (a phillipsite- rich tuff from the surroundings of Naples, Italy, and a bentonite, from Wyoming, USA), exchange kinetics and isotherms of Cu2+, Pb2+ and Zn2+ for Ca2+ at 25 C and 0.1 total normality, were determined and the related kinetic and thermodynamic quantities computed. Comparative results demonstrate that phillipsite-rich tuffs exhibit higher cation exchange capability and selectivity performances towards noxious cations than the montmorillonite clay does, and therefore that they can be considered good substitutes of clay materials to recover and/or rebuild polluted..
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