1,720,960 research outputs found
Cadmium removal mechanisms from aqueous solution by using recycled lignocelluloses
No full textThe three organic residuals of pistachio, peanut, and almond were investigated for the removal capacity and removal mechanism of cadmium ion from aqueous. Adsorption efficiency on reducing cadmium was evaluated with batch experiment parameters, contact time, sorbent dose, pH, and Cd2+ amount. The sorption process of metal ions was defined well with the pseudo-second order kinetic, and Langmuir isotherm model having an adsorption capacity (qe(max)) of 51.28 mg g(-1) of pistachio, 62.11 mg g(-1) of peanut, 78.74 mg g(-1) of almond. The adsorbent was characterized by SEM, FTIR, and elemental analysis. The characterization study revealed that recycled lignocelluloses are composed of rough and porous surfaces with many active sites, contribute to metal ions removal in many ways, such as electrostatic interaction, ion exchange, complex formation, and physical adsorption. These findings highlighted that the shells can be effectively applied removal of divalent metal from aquatic solution. (C) 2021 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University
Mechanism of interaction and removal of zinc with lignocellulosic adsorbents, closing the cycle with a soil conditioner
No full textBatch experiments were performed to remove Zn2+ by adsorption process using organic residuals (pistachio, peanut, and almond) as an adsorbent. The adsorbents were characterized by FTIR spectra, SEM images, and elemental analysis. Optimum adsorption of Zn2+ was obtained at pH 6 with a contact time of 45 min at room temperature with 1.0 g adsorbents. The adsorption of Zn2+ was found to well describe Langmuir isotherm model and a pseudo-second-order rate equation. The maximum adsorption capacity of pistachio, peanut, and almond is as follows; 59.52 mgg-1, 54.64 mgg-1, and 51.81 mgg-1, respectively. Functional groups on shell surfaces can cooperate with metal ions in many ways such as electrostatic interaction, ion exchange, complex formation, and diffusion. This study has shown that pistachio, peanut, and almond shell can be used for reducing Zn2+ from aqueous solutions as an eco-friendly, low-cost adsorbent. The end-product containing organic compounds and zinc can be used as a soil conditioner. Furthermore, the usage of the organic shell as a sorbent for the capturing of zinc from contaminated water ensures both the technical advantage and cost-effectiveness for the sustainable environmental management concept. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University
Adsorption of textile dyes onto iron based waterworks sludge from aqueous solution; isotherm, kinetic and thermodynamic study
No full textThe use of iron based waterworks sludge as an adsorbent for the removal of cationic (Basic Violet 16), anionic (Direct Blue 71, Acid Blue 40, and Reactive Blue 29) and non-ionic (Disperse Brown 19) was investigated. Initial adsorption studies demonstrated that Direct Blue 71 and Disperse Brown 19 were adsorbed poorly by the sludge. Data obtained from further batch studies were applied to commonly used isotherm models. Among them, Langmuir isotherm model were found to be the best fitted one and based on Langmuir isotherm model adsorption capacities were 625 mg/g for Direct Blue 71, 833.34 mg/g for Acid Blue 40, and 3333.34 mg/g for Basic Violet Blue 16. Kinetic examinations were also performed for all dye tested and it was found that adsorption kinetic was best described by pseudo second-order kinetic model. Gibbs free energy values of the dye-sludge system were calculated and the negative values were found for Direct Blue 71, Acid Blue 40 and Basic Violet 16 indicating the spontaneity of the adsorption process. (C) 2011 Elsevier B.V. All rights reserved
ASSESSMENT OF METHANOGENIC ACTIVITY AND KINETICS OF ANAEROBIC GRANULAR SLUDGE
No full textThe study aims to investigate the specific methanogenic activity (SMA) and kinetic coefficients for anaerobic granular sludge under low temperatures. Activity test can be used to outline the operating condition for the system and a parameter to assess the system performance by giving a better understanding of the system performance and stability. The granular sludge samples for SMA test were taken from a lab scale Anaerobic Sequencing Batch Reactor (ASBR) operating for treatment of the low strength wastewater at low temperature. Microbial activities were determined through methane production from acetate. The activities at temperature 25, 15 and 10 degrees C were found as 0.74 gCOD/gVSSd, 0.70 gCOD/gVSSd, and 0.68 gCOD/gVSSd, respectively. As expected, the activity decreased with decreased temperature. First order kinetic model and Gompertz equation was applied to determine the kinetic constant for methane production at batch study. Methane production rate constants for Gompertz equation are as follows; R=0.327 (mlCH(4)h(-1)), M-max=4.97 (ml), and lambda=0.45 at 25 degrees C, R=0.429 (mlCH(4)h(-1)), M-max=3.95 (ml), and lambda=0.98 at 15 degrees C, and R=0.286 (mlCH(4)h(-1)), M-max=3.56 (ml), and lambda=0.83 at 10 degrees C
ASSESSMENT OF METHANOGENIC ACTIVITY AND KINETICS OF ANAEROBIC GRANULAR SLUDGE
No full textThe study aims to investigate the specific methanogenic activity (SMA) and kinetic coefficients for anaerobic granular sludge under low temperatures. Activity test can be used to outline the operating condition for the system and a parameter to assess the system performance by giving a better understanding of the system performance and stability. The granular sludge samples for SMA test were taken from a lab scale Anaerobic Sequencing Batch Reactor (ASBR) operating for treatment of the low strength wastewater at low temperature. Microbial activities were determined through methane production from acetate. The activities at temperature 25, 15 and 10 degrees C were found as 0.74 gCOD/gVSSd, 0.70 gCOD/gVSSd, and 0.68 gCOD/gVSSd, respectively. As expected, the activity decreased with decreased temperature. First order kinetic model and Gompertz equation was applied to determine the kinetic constant for methane production at batch study. Methane production rate constants for Gompertz equation are as follows; R=0.327 (mlCH(4)h(-1)), M-max=4.97 (ml), and lambda=0.45 at 25 degrees C, R=0.429 (mlCH(4)h(-1)), M-max=3.95 (ml), and lambda=0.98 at 15 degrees C, and R=0.286 (mlCH(4)h(-1)), M-max=3.56 (ml), and lambda=0.83 at 10 degrees C
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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