1,720,958 research outputs found
Electrodialysis with Bipolar Membranes for the Sustainable Production of Chemicals from Seawater Brines at Pilot Plant Scale
Full text linkEnvironmental concerns regarding the disposal of seawater reverse osmosis brines require the development of new valorization strategies. Electrodialysis with bipolar membrane (EDBM) technology enables the production of acid and base from a salty waste stream. In this study, an EDBM pilot plant with a membrane area of 19.2 m2 was tested. This total membrane area results much larger (i.e., more than 16 times larger) than those reported in the literature so far for the production of HCl and NaOH aqueous solutions, starting from NaCl brines. The pilot unit was tested both in continuous and discontinuous operation modes, at different current densities (200-500 A m-2). Particularly, three different process configurations were evaluated, namely, closed loop, feed and bleed, and fed-batch. At lower applied current density (200 A m-2), the closed-loop had a lower specific energy consumption (SEC) (1.4 kWh kg-1) and a higher current efficiency (CE) (80%). When the current density was increased (300-500 A m-2), the feed and bleed mode was more appropriate due to its low values of SEC (1.9-2.6 kWh kg-1) as well as high values of specific production (SP) (0.82-1.3 ton year-1 m-2) and current efficiency (63-67%). These results showed the effect of various process configurations on the performance of the EDBM, thereby guiding the selection of the most suitable process configuration when varying the operating conditions and representing a first important step toward the implementation of this technology at industrial scale
Electrodialysis with bipolar membranes for the sustainable production of chemicals from seawater brines at pilot plant scale
Full text linkCoupling Electrodialysis with bipolar membranes with renewable energies through advanced control strategies
No full textThe search for innovative and highly sustainable processes, which lead to the ecological transition, represents one of the most important recent guidelines of the European Union. Powering water treatment technologies with renewable energies, using the process buffering capacity as a way to indirectly store energy has been recently proposed as an effective strategy for smart energy use. With this respect, electrodialysis with bipolar membranes (EDBM) can be particularly suitable due to the high energy intensity, coupled with an extreme flexibility of the process. EDBM is an electromembrane process able to convert a concentrated brine into products with high added value such as acids and bases, simply applying an electric power. The objective of this work has been focused on the development of advanced control systems allowing EDBM to operate under transitory regimes following the highly variable trend of renewable energy availability, adapting the operating conditions and the process targets according to the variable power input offered during a working day. To do this, an EDBM stack at pilot scale (provided by FuMA-Tech GmbH) was operated and tested in Lampedusa in continuous mode (feed and bleed) under two different periods (summer and winter) at fixed target (0.5 of NaOH an HCl). In the hours of the day with available power higher than a minimum threshold (2-6.5 kW), the controller was able to keep the process target, fixed at 0.5M of sodium hydroxide and hydrochloric acid, varying the outlet flowrate of the product from 0.5 up to 3 l min-1. In these operating conditions, the controller was able to guarantee high product quality while still retaining high specific productivity (in the range of 0.1-0.2 kg h-1m-2) and low consumption (in the range of 1.3- 1.9 kWh kg-1 of NaOH and 1.8- 2.4 kWh kg-1 of HCl). In all cases, the parallel control logic allowed to tune the applied voltage in order to meet the electric power availability, while manipulating the outlet flowrate to meet the desired product specification. The obtained results have demonstrated for this first time at the pilot scale how EDBM is a particularly suitable technology to valorise, in industrial relevant scenarios, available saline streams and unstable energy sources, thus pushing towards the industrial implementation according to sustainable and circular values approaches
ELECTRO-DIALYSIS WITH BIPOLAR MEMBRANES FOR A CIRCULAR AND SUSTAINABLE VALORISATION OF WASTE BRINES
No full textIn today rapidly evolving and resource-dependent world, the extraction of minerals from waste streams is emerging as a critical solution to meet the growing demands of various industries. Brines, which are highly concentrated saline solutions, are not only by-products of numerous industrial processes but can also be found in natural environments such as salt lakes and underground reservoirs. Rich in essential minerals like lithium, magnesium, potassium, and sodium chloride, these brines are indispensable for applications ranging from energy storage to agriculture and chemical manufacturing. Membrane processes have become pivotal in this extraction, offering efficient, scalable, and sustainable methods for recovering these valuable minerals. Among these processes, Electro-Dialysis with Bipolar Membranes (EDBM) stands out as a groundbreaking advancement in membrane technology. EDBM provides a sustainable and effective approach to producing acids and bases, recovering vital resources, and treating industrial waste streams. With ongoing improvements in membrane materials, stack design, and process integration, EDBM is becoming increasingly viable across a wide range of industrial applications. As global demand for critical minerals continues to increase, the development and optimization of membrane technologies for mineral recovery from brines are of paramount importance. These technologies are not only essential for supporting the transition to a more sustainable and circular economy but also open new pathways for innovation and economic growth in the industrial sector. As industries continue to seek out sustainable and cost-effective solutions, EDBM and related membrane technologies are poised to play a leader role in shaping the future of green chemistry and resource recovery.The research activities presented in the following PhD thesis, has been devoted to the prototyping of the Electro-Dialysis with Bipolar Membranes technology and to the development and testing of innovative strategies to valorise waste brines. The research aims have mainly focused on developing advanced control strategies for the EDBM process, enabling it to store fluctuating energy coming from renewable sources or smart grids in the form of chemical reagents (e.g., acids and bases). By adjusting process variables based on energy availability and utilizing waste saline streams, this approach allowed to promote circular processes as well as sustainable energy utilization.The present PhD thesis is organized in 8 chapter which are summarized as follow:Chapter 1 presents an overview of brine sources, related issue, innovative solutions to recover it through renewable energy-driven process. Moreover, it provides a brief introduction to the Horizon 2020 European projects, Water-Mining and SEArcularMINE, which have proposed innovative treatment chain for brine valorisation.Chapter 2 provides a general introduction to the electro membrane processes, as EDBM belongs to this class of processes. Moreover, an in-depth description of the EDBM process along with its state of the art is presented.Chapter 3 describes the design and construction of an Electro-Dialysis with Bipolar Membranes stack at pilot scale provided by FuMa-Tech, along with the description of the main part composing the hydraulic circuit such as pumps, valves, data acquisition software and hardware.Chapter 4 outlines a comprehensive experimental campaign carried out in Lampedusa Island, as part of the Water-Mining project. In the initial phase, an analysis of the unit performance was performed under various process configurations such as closed-loop, feed and bleed, and fed-batch, while varying the current density applied to the stack. The best configuration was then selected to test the pilot stack with real solutions for a long-run test (60 hours) in order to demonstrate the scalability of the process for industrial applications.Chapter 5 presents unconventional and innovative process schemes for the EDBM process aimed at reducing the environmental impact within treatment chains for the valorisation of waste brines that use acidic and basic solutions, where the presence of salt has no influence on the up/down stream processes. Chapter 6 presents a study of the dynamic behaviour of the EDBM process. A linearized model of the process was derived through the application of step tests to the real process. Subsequently, the design and testing of advanced controllers were presented, aimed at operating the EDBM process under highly transient energy sources, such as solar energy. These controllers successfully adapted to the non-stationary nature of the input energy while maintaining the product quality at the target value.Chapter 7 provides a description of the design and development of a new pilot-scale EDBM stack provided by Water Treatment Solutions (WTS) within the SEArcularMINE project. Additionally, it presents the role of EDBM in the treatment chain and the technological solutions implemented to increase the Technology Readiness Level (TRL) of the technology compared to the FuMa-Tech. Furthermore, a comprehensive comparison between the FuMa-Tech and the WTS EDBM stacks was performed, at three different current densities (i.e. 200, 300 and 400 A m-2). This comparison allowed for the identification of the best technological solution for future industrial-scale implementations of the EDBM technology.Chapter 8 focuses on the testing of a thermal desalination called Mechanical Vapor Compression (MVC). A long-run test, of about 20 hours, was performed using the real waste brine coming from the SEArcularMINE treatment chain. The results show how implementing this technology in synergy with EDBM allows for the elimination of effluent discharge from the EDBM process, recovering industrial-grade NaCl and a concentrated solution rich in trace elements such as Lithium, Rubidium, Caesium, and Strontium, thereby generating a Zero Liquid Discharge process as outlined in the SEArcularMINE treatment chain
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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