Mark W. Hlawitschka

Johannes Kepler University of Linz

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Nils Haneklaus

North-West University

Hans‐Jörg Bart

University of Kaiserslautern

Ali Maged

Suez University

Alexander Keller

Johannes Kepler University of Linz

Christian Drumm

Covestro (Germany)

Sean Williams

Tufts University

Hassan Soltan Hassan

Universidad Nacional Autónoma de México

Lucas Meili

Universidade Federal de Alagoas

Nguyet-Minh Nguyen

Van Lang University

Mathew Maltrud

Los Alamos National Laboratory

Cooperative Institutions

University of Kaiserslautern

Daimler (Germany)

Los Alamos National Laboratory

Al-Balqa Applied University

Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau

Universidade Federal de Alagoas

Johannes Kepler University of Linz

University of California, Davis

Assiut University

University of Jordan

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Visualization and Analysis of Eddies in a Global Ocean Simulation

Computer Graphics Forum (2011)

Sean Williams Matthew Hecht Mark Petersen Richard Strelitz Mathew Maltrud

Abstract We present analysis and visualization of flow data from a high‐resolution simulation of the dynamical behavior of the global ocean. Of particular scientific interest are coherent vortical features called mesoscale eddies. We first extract high‐vorticity features using a metric from the oceanography community called the Okubo‐Weiss parameter. We then use a new circularity criterion to differentiate eddies from other non‐eddy features like meanders in strong background currents. From these data, we generate visualizations showing the three‐dimensional structure and distribution of ocean eddies. Additionally, the characteristics of each eddy are recorded to form an eddy census that can be used to investigate correlations among variables such as eddy thickness, depth, and location. From these analyses, we gain insight into the role eddies play in large‐scale ocean circulation.

Eddy

10.1111/j.1467-8659.2011.01948.x

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Citations (48)

Manganese recycling of spent lithium-ion batteries via solvent extraction

Separation and Purification Technology (2021)

Alexander Keller Mark W. Hlawitschka H.‐J. Bart

Phosphoric acid

10.1016/j.seppur.2021.119166

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Citations (37)

Reactive Mass Transfer of Single NO Bubbles and Bubble Bouncing in Aqueous Ferric Solutions – A Feasibility Study

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles (2017)

Mark W. Hlawitschka Martin Oßberger Christian Backes Peter Klüfers Hans‐Jörg Bart

Reactive bubble columns are widely used in the chemical, petrochemical, biochemical and metal industries. While the reactive mass transfer around a single spherical shaped bubble is quite well described in literature, the influence of hydrodynamic interactions, such as bubble bouncing or coalescence on mass transfer – with and without chemical reaction – is not well understood. As to this, high resolution simulations and sophisticated experimental analysis based on high-speed camera images and local color changes gives a new firm basis. In this work, a new system is presented, based on Nitric Oxide (NO) gas absorbed in a FeII-solution. The reaction rate can be adjusted by the addition of ligands and the resulting local color change is detected. The impact of the colliding bubbles leads to a deformation of the bubble shapes and creates a fast movement of the bubble interfaces, which, finally, leads to an increased mass transfer. The results of five tested ligands reveal the high potential of the reactive FeII(NO) system to investigate basic phenomena affecting yield and selectivity of mixing-sensitive chemical reactions.

Coalescence (physics)

Mass transfer coefficient

Reaction rate

10.2516/ogst/2017006

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Citations (12)

Towards understanding climate change: Impact of land use indices and drainage on land surface temperature for valley drainage and non-drainage areas

Journal of Environmental Management (2023)

Sherif Ahmed Abu El-Magd Ahmed M. Masoud Hassan Soltan Hassan Nguyet-Minh Nguyen Quoc Bao Pham

10.1016/j.jenvman.2023.119636

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Citations (7)

Nanoclays in water treatment: Core concepts, modifications, and application insights

Journal of Water Process Engineering (2024)

Luiz D. Silva Neto Ali Maged Rafaela Gabriel Pollyanna V.S. Lins Nils Haneklaus

10.1016/j.jwpe.2024.106180

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Citations (2)

Experimental investigation of local bubble properties: Comparison to the sectional quadrature method of moments

AIChE Journal (2019)

Jan Schäfer Mark W. Hlawitschka Menwer Attarakih Hans‐Jörg Bart

Abstract In recent years, population balance models coupled to computational fluid dynamics have been used as a tool to model bubbly flows. In this work, we established a setup to measure the local size distribution, the velocity and orientation of bubbles in different zones of a bubble column. As a population balance model, we used the sectional quadrature method of moments for the first time in OpenFOAM to simulate the local change in the bubble size distribution and compared its results to the quadrature method of moments as well as to the experimental results. A satisfactory agreement between local experimental values of three investigated flow rates and simulations were found and enables the characterization of heterogeneous bubbly regimes as found in industrial reactive bubble columns.

Quadrature (astronomy)

10.1002/aic.16694

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Citations (17)

CFD simulations and particle image velocimetry measurements in an industrial scale rotating disc contactor

AIChE Journal (2010)

Christian Drumm Mark W. Hlawitschka Hans‐Jörg Bart

Abstract Fluid dynamics of the single‐phase and two‐phase flow in a segment of a rotating disc contactor (RDC) liquid–liquid extraction column with 450 mm inner diameter were studied by performing computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) measurements. The fluid dynamics were investigated to test the predictivity of CFD at industrial scale. Different turbulence models in conjunction with the Eulerian approach were applied in the single‐phase and two‐phase simulations. The turbulent flow characteristics were analyzed by PIV measurements to validate the CFD simulations. An iso‐optical system composed of CaCl 2 /water–butylacetate allows for the two‐phase PIV measurements. Local turbulent energy dissipation was derived from velocity gradients in PIV data. In this connection, the influence of the PIV spatial resolution on the measured energy dissipation was also analyzed, and different fit functions were tested to scale the measured energy dissipation. Simulated velocity fields as well as the energy dissipation were compared with the experimental PIV data. The results from the simulations and experiments are in good agreement. The work shows that CFD can predict hydrodynamic characteristics even at bigger scales but is still subject to some minor restrictions. © 2010 American Institute of Chemical Engineers AIChE J, 2011

Velocimetry

Contactor

10.1002/aic.12249

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Citations (34)

Synergistic mechanisms for the superior sorptive removal of aquatic pollutants via functionalized biochar-clay composite

Bioresource Technology (2023)

Ali Maged Ahmed M. Elgarahy Mark W. Hlawitschka Nils Haneklaus Ashok Kumar Gupta

This study investigated the successful synthesis of functionalized algal biochar-clay composite (FBKC). Subsequently, the sorption performance of FBKC towards norfloxacin (NFX) antibiotic and crystal violet dye (CVD) from water was extensively assessed in both batch and continuous flow systems. A series of characterization techniques were carried out for FBKC and the utilized precursors, indicating that the surface area of FBKC was increased thirty-fold with a well-developed pore structure compared to the original precursors. FBKC demonstrated a maximum sorption capacity of 192.80 and 281.24 mg/g for NFX and CVD, respectively. The suited fitting of the experimental data to Freundlich and Clark models suggested multi-layer sorption of NFX/CVD molecules. The mechanistic studies of NFX/CVD sorption onto FBKC unveiled multiple mechanisms, including π-π interaction, hydrogen bonding, electrostatic attraction, and surface/pore filling effect. The estimated cost of 5.72 €/kg and superior sorption capacity makes FBKC an efficient low-cost sorbent for emergent water pollutants.

Crystal violet

10.1016/j.biortech.2023.129593

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Citations (25)

Recovery of excess sulfuric acid in the lithium-ion batteries recycling process

Separation and Purification Technology (2024)

Alexander Keller Mark W. Hlawitschka

Excess sulfuric acid which is needed for the leaching process of spent lithium-ion batteries is commonly neutralized generating significant waste streams. This research aims to extract and recover sulfuric acid using tri-n-octylamine as an extraction agent. 1-octanol, 2-ethylhexanol, and tributyl phosphate are investigated as synergetic extractants and phase modifiers. An equilibrium study is carried out on both, sulfuric acid and leachate. The equilibrium constant and the stoichiometric coefficient for the overall equilibrium reaction are determined by slope analysis. The enthalpy and Gibb's enthalpy are studied by investigation of the effect of temperature. Regarding the experiments using leachate, the co-extraction of aluminum, cobalt, copper, iron, lithium, manganese, and nickel is studied, too. Moreover, the co-extraction of water is investigated as a significant increase in metal concentration in the raffinate is observed.

10.1016/j.seppur.2024.126965

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Citations (2)