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![Figure 3. Current distribution in parallel plate electrode [2]](profile/Abbas-Sulaymon/publication/278026699/figure/fig3/AS:392025066229762@1470477467372/Current-distribution-in-parallel-plate-electrode-2_Q320.jpg)
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A practical and scalable synthesis of 3-amino-2,2-dimethylpropanamide, a key intermediate of Aliskirenis described. Process optimization of dimethylation, ammonolysis and hydrogenation steps and their scale up challenges were discussed.
As humans, we are uniquely competent at incorporating ourselves into groups that scale up from a few members to millions of individuals to engage in joint activities in social circles of varying sizes. Yet, the question of how a group's survival depends on its social structure is not well understood. In an analysis of more than 10 122 real-life onl...
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... In these studies, scale-up is often accomplished by creating a cell stack of unit cells; however, scale-up can also be achieved by increasing the electrode active area. An important condition for scaling-up of electrochemical devices is maintaining electrical similarity, such as keeping a constant interelectrode gap [24]. Other important factors to consider are kinematic similarity, which relates to the gas or liquid flows in the system, and thermal similarity, which refers to the temperature profiles in corresponding parts of the system. ...
The design of a 10 cm2 (3.4 cm by 3.4 cm) and a 100 cm2 (10 cm by 10 cm) anion exchange membrane (AEM) water electrolyser cell for hydrogen production are described. The AEM cells are based on a zero-gap configuration where the AEM is sandwiched between the anode and cathode so as to minimise voltage drop between the electrodes. Nonprecious nickel-based metal alloy and metal oxide catalysts were employed. Various experiments were carried out to understand the effects of operating parameters such as current densities, electrolyte concentrations, and testing regimes on the performance of both 10 cm2 and 100 cm2 AEM electrolyser cells. Increasing electrolyte concentration was seen to result in reductions in overpotentials which were proportional to current applied, whilst the use of catalysts improved performance consistently over the range of current densities tested. Extended galvanostatic and intermittent tests were demonstrated on both 10 cm2 and 100 cm2 cells, with higher voltage efficiencies achieved with the use of electrocatalysts. Stability tests in the 100 cm2 AEM electrolyser cell assembled with catalyst-coated electrodes demonstrated that the cell voltages remained stable at 2.03 V and 2.17 V during 72 h operation in 4 M KOH and 1 M KOH electrolyte, respectively, at a current density of 0.3 A cm−2 at 323 K. The inclusion of cycling load tests in testing protocols is emphasized for rational evaluation of cell performance as this was observed to speed up the rate of degradation mechanisms such as membrane degradation.
... Therefore, for the reactor-scale process of the device, the geometry, operating conditions, cost and quantity of materials have been evaluated (Nadebaum & Fahidy, 1980;Walsh & Reade, 1994). An electrochemical reactor was also used to assess factors such as the electrochemical potential and the electric current limit (Houghton & Kuhn, 1974;White et al., 1983;Bisang & Kreysa, 1988;Li, 2017) as well as the distribution of both of these factors, which allowed for reductions in manufacturing costs to be realized (Nadebaum & Fahidy, 1980;Sulaymon & Abbar, 2012). Such work improved the removal of iron and so the whiteness of the kaolin obtained. ...
High-whiteness kaolinite mining reserves are scarce. In some locations, it is necessary to remove material to access them (adding to the cost). Therefore, processes have been developed to eliminate contaminants, such as iron, and provide alternatives to the used contaminated materials that, after being treated, meet quality criteria. In our previous research, we developed an electrochemical process for kaolin whitening at the laboratory level and bench scale, demonstrating the reaction mechanisms that occur during the removal of iron from kaolin. However, the geometry used at the laboratory level does not present the most suitable position for the electrodes. Therefore, in the present study, we focused on the geometry and the function of the electrodes. This is necessary during the escalation process to reach the pilot-scale level. The study was carried out using computer-aided engineering in the COMSOL Multiphysics computer program and by analysing the distribution of the electric potential and the electric current of the geometries considered while performing the scaling. The results indicated that the change in the anode position from perpendicular to parallel to the discs improved the distribution of electric current density on the cathode surface and so increased the elimination of iron through electrochemical deposition. Similarly, to reduce the amount of material used in the construction of the reactor, the anode-size effect was analysed, revealing that relatively small anodes improved the distribution of electric current density over the entire surface of the electrode and not only at the edges.
... Note that the higher cell current could be readily achieved by cell scale-up, such as enlarging the electrode area, stacking layers of electrodes, and operating more reactors. 48,49 With considerations of real-world applications, air was supplied to cathode instead of ultrapure O 2 gas. The cell exhibited high selectivity (∼90%) and high activity (0.68 mol g catalyst −1 hr −1 @ 10 mA cm −2 , yellow in Figure 4c), suggesting 2e − ORR was kinetically favored even with the existence of other inert gases such as nitrogen, although a higher cell potential was needed to drive the reaction. ...
Advanced oxidation processes (AOPs) target the chemical destruction of a wide range of nonbiodegradable, toxic, and recalcitrant organic pollutants instead of removal via physical separation, which produces contaminant-laden concentrates or solids. Hydrogen peroxide (H2O2) is the most widely used precursor that produces a highly reactive and nonselective hydroxyl radical at the site of an AOP through activation by UV irradiation. The potential for AOPs to meet the growing demand of transforming a centralized treatment and distribution practice into a modular, small-scale, and decentralized treatment paradigm can be maximized by innovative technologies that can synthesize precursor chemicals also at the site of water treatment, eliminating the need for a continuous chemical supply. We here present an electrochemical H2O2 generation cell that produces a large quantity of H2O2 while consuming only 0.2 to 20% of the total electricity consumption of AOPs in various AOP application scenarios employing UV activation. We achieve high electrochemical H2O2 production efficiency by synthesizing an anthraquinone-modified polyaniline composite that enables an efficient two-electron oxygen reduction reaction. Polyaniline functions as a conductive support with abundant attachment sites, and anthraquinone ensures selective H2O2 generation. In a flow cell equipped with a gas diffusion cathode, H2O2 can be produced at a rate of 1.80 mol gcatalyst–1 hr–1 at 100 mA with a Faradaic efficiency of 95.83%. Finally, we examined the H2O2 production capability of the device with simulated drinking water and wastewater as feed electrolytes to demonstrate its potential for real-world operation scenarios.
... Bei einer Hochskalierung werden oft die Dimensionsverhältnisse des Reaktors gleich gelassen. Allerdings werden elektrochemische Prozesse maßgeblich von der Stromund Potentialverteilung bestimmt, welche sich durch eine Vergrößerung des Aufbaus ändern[286,287]. Demnach gilt es, hier vor allem die Elektrodenanordnung beizubehalten. ...
Das Material Graphen besitzt eine Reihe außergewöhnlicher und interessanter Eigenschaften, deren Vorteile bereits für eine Vielzahl von Anwendungen gezeigt wurden. Aufgrund seines hohen Potentials wird erwartet, dass Graphen in Zukunft die aktuellen Technologien revolutionieren wird. Jedoch wird der industrielle Durchbruch bisher durch das Fehlen eines geeigneten Herstellungsverfahrens, das den industriellen Anforderungen genügt, gehindert. Ein solches Verfahren muss Graphen sowohl in großen Mengen als auch mit hoher Qualität liefern können. Die Herstellung von Graphenflocken durch eine Exfoliation von Graphit ermöglicht eine Massenproduktion, allerdings ist die Qualität dieses Graphens noch mangelhaft.
In dieser Arbeit wird ein Exfoliationsverfahren, das auf der elektrochemischen Reduktion von Naturgraphitflocken basiert, untersucht mit dem Ziel, dessen physikalische und chemische Prozesse zu verstehen und so das Exfoliationsverfahren zu optimieren. Im Gegensatz zu den üblichen elektrochemischen und chemischen Verfahren wird das Graphen nicht oxidiert, was in nicht reparablen Defekten resultieren würde, sondern hydriert. Es wird gezeigt, dass diese Funktionalisierung die Exfoliation unterstützt. Gleichzeitig ist sie vollständig reversibel und erzeugt somit keine permanenten Defekte. Exfoliert wird der Graphit durch die Kombination aus Interkalation, Gasentwicklung und Hydrierung. Die so entstehenden Graphenflocken und die Auswirkung dieser Prozesse auf ihre Morphologie werden ausführlich charakterisiert. Die Untersuchungen zeigen, dass die elektrochemische Reduktion bis zu etwa 30 % der Kohlenstoffatome hydriert. Diese kann durch thermische Behandlung entfernt werden, wonach die Graphenflocken eine niedrige Defektdichte aufweisen. Weiterhin besitzen sie eine große laterale Flockengröße und bestehen überwiegend aus Multilagengraphen. Mit diesen strukturellen Eigenschaften können die Flocken eine hohe elektrische Leitfähigkeit erreichen, wie anhand von transparenten Filmen und in Superkondensatorelektroden gezeigt wird. Durch das gewonnene Verständnis des Exfoliationsmechanismus und der Identifikation seiner bestimmenden Parameter wird der Prozess hinsichtlich der Graphenausbeute optimiert, wodurch eine Effizienz von 80 % erreicht wird. Weiterhin wird der Einfluss einer Skalierung auf den Exfoliationsprozess untersucht und dessen Skalierbarkeit demonstriert. Die Untersuchungen erweitern das Verständnis der kathodischen Exfoliation und der elektrochemischen Hydrierung. Die Ergebnisse zeigen das Potential des präsentierten Exfoliationsverfahrens für die Massenproduktion von qualitativ hochwertigen Graphenflocken.
... Therefore, the mathematical modeling proposed here could be used suitably for scaling-up purposes in agreement with [26]. Moreover, the scaling-up of electrochemical reactors can be achieved by using several similar criteria such as those of geometric similarity, kinematic and thermal similarity and current/potential similarity, which are reported in reference [39,40]. A comparison of mathematical models for electrochemical degradation of organic pollutants at an electrochemical flow reactor is presented in Table 2. ...
The objective of this work was to develop a mathematical model of an electrochemical flow reactor for the degradation of 2- chlorophenol. The reactor operates in batch recirculation and undivided mode under mass transport control and under galvano- static conditions. The mathematical model proposed here was simulated on COMSOL Multiphysic® 5.3 software (involving the continuity and Navier-Stokes equation in a laminar regime, and the diffusion-convection equation with reaction term) interacting with the MATLAB® version R 2017a software (continuous stirred tank). The electrolysis process was carried out at a current density of 0.14 A m−2, a liquid flow rate of 1 L min−1 and pH = 7.3. The main results show that the mathematical model proposed here is in a very good agreement with the experimental study (correlation coefficient of 0.9917 and a reduced root-mean-square error of 0.4041). The final concentration of 2-chlorophenol estimated by the mathematical model was 0.0013 mol m−3, while the experimental concentration reached was 0.0001 mol m−3, confirming the predictive capacity of the mathematical model, as well as the efficiency of the electrochemical process implemented.
... The Tafel slope b can be obtained from this plot. Apart from that, the current density |i| and the medium conductivity j have to be measured in the small scale experiments (Andricacos et al., 1999;Sulaymon and Abbar, 2012). ...
In times of energy revolution, bioelectrochemistry is a growing field of research, either for the generation of electrical energy from organic substrates or the use of electrical energy to produce various products. By now, this technology is on the turning point from lab scale to industrial applications. Unfortunately, there is still a lack of well characterized, scalable reactor systems that are capable of hosting different bioelectrochemical processes, linking lab scale research to industrial application. In this paper, we introduce a two-chamber bioelectrochemical bubble-column reactor (one liter working volume), which can be used as microbial fuel cell as well as for microbial electrosynthesis and is especially advantageous for processes with gaseous substrates. It is designed flexible in terms of electrode material and area, membrane material and area, and capable of hosting continuous processes. It is a promising replacement of lab-scale H-cells for wider screening possibilities with regard to industrial applications. We characterized the reactor by giving key values such as kLa and gas hold up, and suggest scale-up parameters. These are, for example, dimensionless numbers like Reynolds and Wagner number and different ratios that should be kept constant during scale-up. Therefore, this paper can be a guideline for the development and scale-up of bioelectrochemical systems.
... The scaling up of conventional electrochemical reactors to industrial capacity is usually achieved using one of two strategies [162]: (i) increasing the surface area of the electrodes or (ii) stacking individual cells. Two factors are relevant to the first strategy. ...
Microbial electrolysis cells (MECs) are cutting edge technology with great potential to become an alternative to conventional wastewater treatments (anaerobic digestion, activated sludge, etc.). One of the main features of MECs is that they allow organic matter present in wastewater to be converted into hydrogen thus helping to offset the energy consumed during treatment. There are already some large-scale experiments under way but MECs are far from being a mature technology; important challenges, mostly techno-economic in nature (cost of materials, hydrogen management, etc.) remain. This study provides an up-to-date review of the latest developments in MECs, paying special attention to those aspects that may be critical to the commercial viability of MECs for wastewater treatment and hydrogen production. It explores the suitability of different cell configurations and the scalability of MEC designs; it also reviews many of the laboratory, semi-pilot and pilot scale experiments. The review provides a critical analysis of the current state and the future prospects for MECs; it highlights factors crucial to the development of successful MEC designs, identifies potential application niches and discusses the integration of MECs with energy transportation systems.
... Although several authors describe reaction systems with larger electrode areas and volumes, often no scale-up criteria were applied. In the scale-up of (electro)chemical processes, dimensional analysis is a proven method for developing functional relationships that describe any given process in a dimensionless form [87]. Improving reaction productivity is the main challenge on the way to benefit from the advantages of electrochemistry in biocatalysis. ...
In bioelectrochemical systems (BESs) at least one electrode reaction is catalyzed by microorganisms or isolated enzymes. One of the existing challenges for BESs is shifting the technology towards industrial use and engineering reactor systems at adequate scales. Due to the fact that most BESs are usually deployed in the production of large-volume but low-value products (e.g., energy, fuels, and bulk chemicals), investment and operating costs must be minimized. Recent advances in reactor concepts for different BESs, in particular biofuel cells and electrosynthesis, are summarized in this review including electrode development and first applications on a technical scale. A better understanding of the impact of reactor components on the performance of the reaction system is an important step towards commercialization of BESs.
