1,720,957 research outputs found
Synthesis and CO2 adsorption capacity of biomass waste functionalized by nanoparticles
Full text linkTwo composite materials were synthesized based on sodium alginate and biochar derived from licorice processing waste functionalized with silicon dioxide nanoparticles (SiO2) and iron oxide (Fe2O3), respectively, enabling the valorization of industrial waste. The adsorptive capacities of the two materials (Alg-SiO2 and BCLFe2O3) toward CO2 in the gaseous stream with nitrogen were evaluated by acid titration of carbonates present in a trap for CO2 consisting of a KOH solution placed downstream of the adsorption column. The aim of the present work is to evaluate the CO2 adsorption capacity of material functionalized by nanoparticles. Adams–Bohart, Thomas models, and % removal efficiency curves for the adsorption were examined to investigate the dynamic behavior of the column. From the tests performed in CO2 and N2 flow, the BCL-Fe2O3 material was demonstrated to have an adsorbent higher capacity than Alg-SiO2, respectively CO2 adsorbed 25 and 6 mg/g
Nanocatalysts Used for Tar Cracking Present in the Syngas from Gasification of Municipal Solid Waste
Full text linkWaste gasification is considered one of the most promising potential routes for the fuel gas production since it represents one of the most powerful and reliable approaches for the biomass conversion. Tar is the undesirable, but unavoidable, by-product of the gasification processes. not only does it lower the overall energy conversion efficiency, but it also leads to potential contamination and clogging problems, thus It is of paramount importance to remove it. Tar can be converted into gases by catalytic cracking, which has become a hot research topic in biomass pyrolysis and gasification technologies. Various tar cracking catalysts have been extensively studied and current advances in the study of nanomaterials have attracted wide interest for their catalytic properties compared to their bulk counterparts: in particular, the supported transition metal NanoParticles show the best catalytic characteristics for tar cracking. This work gives a comprehensive overview of the most promising nanocatalysts for tar removal reported in the litterature: it reviews the different synthesis methods and the catalytic properties of the produced nanocatalysts, thus providing useful information for the understanding of the most promising routes for an efficient conversion of biomass tar into combustible gas
Sustainable production of hydrogen, pyridine and biodiesel from waste-to-chemicals valorization plant: Energy, exergy and CO2-cycle analysis
Full text linkThis study deals with the simulation of waste-to-chemicals plant for the conversion of municipal solid waste to hydrogen, biodiesel and pyridine. The study analyses a Waste to Chemical plant, in order to evaluate the future scenarios of the integrated management of municipal waste from a technical and economic point of view and compare them, both in terms of material flows and related costs. In a first phase, the characteristics of the simulation model created with the help of the Aspen Plus software are analysed. Subsequently, with the help of a calculation model, the operating costs, emissions and energy and exergy efficiency are evaluated for the two identified scenarios.
Starting from about 3000 t/h of waste, as a main result, about 8.4 t/h of pyridine and 300 t/h of biodiesel are produced and about 7.94 t/h of H2 as a by-product. The main purpose of the design cycle is to reduce the amount of waste to landfill, valorising it and limiting CO2 emitted in the atmosphere at the same time.
Two system configurations are considered to maximize the reuse of all waste streams. In particular, the comparison was made between two scenarios: in the first the stream separated by extraction is considered a waste for the plant, while in the second scenario, this stream is sent to a fermentation section to obtain an excess bioethanol stream, which represents another product with high added value. The treatment of the stream separated from the extraction in the second scenario allows to obtain an additional stream of bioethanol in addition to the target products.
A complete energy, exergy, environmental and economic analysis of the simulated plant have been carried out. The work shown that in the second case the waste exergy is dramatically reduced, leading to a raise of exergy efficiency from 30.2% up to 84.9%. While, from the environmental point of view both scenarios have low CO2 emissions, 0.52 kgCO2/kg products and 0.87 kgCO2/kg products respectively
Nanoparticles Used for CO2 Capture by Adsorption: a Review
No full textRapid industrialization, technological advancement, and innovation have led to a significant rise in carbon
emissions globally, resulting in the growing problem of climate change. With the advancement of
nanotechnology, the adsorption is becoming an effective strategy to directly capture CO2 with nanomaterials.
This mini-review deals with the investigation for physical adsorption, amine-modified nanomaterials for
chemisorption, and moisture-swing nanomaterials for chemisorption. The purpose is to highlight the current
technologies available for a simple, environmentally safe, non-toxic, low-cost CO2 capture. In detail, this study
examines several CO2 capture nanomaterials with an emphasis on economical and environmentally safe low to
high temperature solid adsorbents
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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