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Lithiumgewinnung aus geothermischen Solelösungen mittels eines elektrochemischen Systems unter Verwendung von LiMn₂O₄-Elektroden
No full textThe urgent need to mitigate climate change is accelerating the global transition toward renewable energy systems, which in turn is driving an unprecedented demand for energy storage materials. Among these, lithium has become a critical resource for enabling large-scale electrification and supporting the decarbonization of the energy sector. The presence of lithium-bearing geothermal reservoirs in Germany offers a unique opportunity for domestic lithium production, contributing to resource security and reducing dependence on imports.
In this context, electrochemical lithium ion pumping (ELIP) has emerged as a promising direct lithium extraction (DLE) technology. Its main advantages lie in high selectivity, potential energy efficiency, and compatibility with diverse brine chemistries. Nevertheless, ELIP still faces significant challenges related to its scalability and to the inherently low lithium concentrations found in natural geothermal brines. Addressing these limitations requires a combined understanding of electrode materials, reactor design, and process operation.
This thesis investigates the development of a lithium recovery system based on the ELIP concept, following a stepwise approach from the characterization of active materials to process-level implementation. The first part provides a comprehensive review of ELIP technologies and their working principles, outlining the rationale for selecting the LiMn₂O₄/λ-MnO₂ (LMO) rocking-chair configuration as the focus of this work. Based on this selection, experimental efforts were directed toward developing and characterizing composite LMO electrodes and evaluating the electrochemical performance of the rocking-chair system under conditions representative of geothermal brines.
Composite LMO electrodes with different mass loadings were prepared, and their lithium (de)intercalation behavior was examined in a circulating Flow-By reactor using an artificial brine containing 30 mM Li and 1.3 M Na, which reproduces the Na/Li ratio present in geothermal brines from the Upper Rhine Graben. Lithium selectivity was evaluated both at the electrode level and in the full LMO rocking-chair system in the presence of competing cations found in geothermal brines. Key performance indicators, including energy consumption per mole of lithium extracted, Faradaic efficiency, and lithium separation factor with respect to impurity ions, were quantified to assess both the energy efficiency and separation performance of the complete system under controlled Flow-By operation.
Building upon this foundation, a continuous-flow reactor concept was designed and experimentally validated to demonstrate lithium extraction under conditions simulating the progressive lithium depletion that occurs during brine circulation. In this design, the reactor is divided into functional zones that are tailored to local variations in lithium concentration, mitigating mass transport limitations while reducing the overall electrode area required for high lithium recovery. This zoned configuration allowed up to 90 % lithium recovery from artificial geothermal brine. Process-level parameters such as brine hydrodynamics and reactor retained volume were analyzed, providing criteria for scaling up the electrochemical unit within hybrid geothermal plants.
Finally, a detailed electrochemical analysis was carried out to optimize the cathodic process, identified as a primary constraint on overall system performance. Cyclic voltammetry and electrochemical impedance spectroscopy, combined with a transmission line model for porous electrodes, were used together with systematic variations in electrode mass loading and hydrodynamic conditions to deconvolute the contributions of equilibrium potential, as well as surface and concentration overpotentials. These findings provide quantitative insight into the energy and electrode capacity losses occurring under depleted brine conditions and establish a framework for improving both energy and material efficiency of future large-scale ELIP systems.
Overall, this work bridges the gap between laboratory proof of concept and process-level design, laying the scientific and engineering foundations for scalable electrochemical direct lithium extraction from geothermal brines.Der dringende Bedarf, den Klimawandel zu begrenzen, beschleunigt weltweit die Energiewende und führt zu einer zunehmenden Nachfrage nach Materialien für die Energiespeicherung. Unter diesen hat sich Lithium zu einer entscheidenden Ressource entwickelt, um die großflächige Elektrifizierung zu ermöglichen und die Dekarbonisierung des Energiesektors zu unterstützen. Das Vorhandensein von lithiumhaltigen Reservoirs in Deutschland bietet eine einzigartige Gelegenheit für eine heimische Lithiumproduktion aus geothermischen Solen, die zur Rohstoffsicherheit beiträgt und die Abhängigkeit von Importen verringert.
In diesem Zusammenhang stellt das elektrochemische Lithium-Ionen-Pumpen-Verfahren (Electrochemical Lithium Ion Pumping, ELIP) eine vielversprechende Technologie der direkten Lithiumextraktion (Direct Lithium Extraction, DLE) dar. Die Hauptvorteile dieser Methode liegen in ihrer hohen Selektivität, potenziellen Energieeffizienz und Kompatibilität mit Solen unterschiedlicher chemischer Zusammensetzung. Dennoch steht ELIP weiterhin vor bedeutenden Herausforderungen hinsichtlich seiner Skalierbarkeit sowie der von Natur aus geringen Lithiumkonzentrationen in geothermischen Solen. Die Bewältigung dieser Einschränkungen erfordert ein kombiniertes Verständnis von Elektrodenmaterialien, Reaktordesign und Prozessgestaltung.
Diese Dissertation untersucht die Entwicklung eines Lithiumrückgewinnungs-systems auf der Grundlage des ELIP-Konzepts und folgt dabei einem schrittweisen Ansatz, von der Charakterisierung aktiver Materialien bis hin zur Implementierung auf Prozessebene. Der erste Teil bietet einen umfassenden Überblick über ELIP-Technologien und deren Funktionsprinzipien und erläutert die Gründe für die Auswahl der LiMn₂O₄/λ-MnO₂ (LMO) Rocking-Chair-Konfiguration als Schwerpunkt dieser Arbeit. Auf dieser Grundlage wurden experimentelle Arbeiten zur Entwicklung und Charakterisierung von Kompositelektroden aus LMO durchgeführt und das elektrochemische Verhalten des Rocking-Chair-Systems unter Bedingungen bewertet, die geothermischen Solen entsprechen.
LMO-Kompositelektroden mit unterschiedlichen Massenbeladungen wurden her-gestellt und ihr Lithium-(De-)Interkalationsverhalten in einem zirkulierenden Flow-By-Reaktor untersucht, der eine künstliche Sole mit 30 mM Li und 1,3 M Na enthielt. Diese Zusammensetzung reproduziert das Na/Li-Verhältnis typischer geothermischer Solen aus dem Oberrheingraben. Die Lithiumselektivität wurde sowohl auf Elektrodenebene als auch im vollständigen Rocking-Chair-System in Gegenwart konkurrierender Kationen bewertet. Leistungsparameter, darunter der Energieverbrauch pro extrahiertem Mol Lithium, die faradische Effizienz und der Lithium-Trennfaktor gegenüber konkurrierenden Kationen, wurden quantifiziert, um sowohl die Energieeffizienz als auch die Selektivität des gesamten Systems unter kontrolliertem Flow-By-Betrieb zu bewerten.
Aufbauend auf diesen Ergebnissen wurde ein kontinuierlich betriebener Reaktorkonzept entworfen und experimentell validiert, um die Lithiumextraktion unter Bedingungen zu demonstrieren, die die fortschreitende Lithiumerschöpfung während der Solezirkulation simulieren. In diesem Design ist der Reaktor in Funktionszonen unterteilt, die an der lokalen Lithiumkonzentration angepasst sind, wodurch Stofftransportbegrenzungen gemindert und gleichzeitig die insgesamt benötigte Elektrodenfläche für eine hohe Lithiumrückgewinnung reduziert werden. Mit dieser zonierten Konfiguration konnte eine Lithiumrückgewinnung von bis zu 90 % aus künstlicher geothermischer Sole erreicht werden. Prozessparameter wie die Hydrodynamik der Sole und das im Reaktor Retentionsvolumen wurden analysiert, um Kriterien für die Hochskalierung der elektrochemischen Einheit innerhalb hybrider Geothermieanlagen zu liefern.
Abschließend wurde eine detaillierte elektrochemische Analyse durchgeführt, um den kathodischen Prozess zu optimieren, der als primäre Einschränkung der Gesamtleistung des Systems identifiziert wurde. Zyklovoltammetrie und elektrochemische Impedanzspektroskopie wurden in Kombination mit einem Ersatzschaltbild für poröse Elektroden sowie systematischen Variationen der Elektrodenmassenbeladung und hydrodynamischen Bedingungen eingesetzt, um die Beiträge von Gleichgewichtspotential sowie Oberflächen- und Konzentrationsüberspannungen zu entflechten. Diese Ergebnisse liefern quantitative Einblicke in die Energie- und Kapazitätsverluste der Elektroden unter lithiumarmen Bedingungen und bilden die Grundlage für eine verbesserte Energie- und Materialeffizienz zukünftiger großtechnischer ELIP-Systeme.
Insgesamt schlägt diese Arbeit die Brücke zwischen Labor-Proof-of-Concept und Prozessdesign und legt die wissenschaftlichen und technischen Grundlagen für eine skalierbare elektrochemische direkte Lithiumextraktion aus geothermischen Solen
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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