The Experts below are selected from a list of 705 Experts worldwide ranked by ideXlab platform
Wolfgang Uhl - One of the best experts on this subject based on the ideXlab platform.
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Pore diffusion limits removal of monochloramine in treatment of swimming pool water using granular activated carbon.
Water Research, 2018Co-Authors: Bertram Skibinski, Christoph Gotze, Eckhard Worch, Wolfgang UhlAbstract:Overall apparent reaction rates for the removal of monochloramine (MCA) in granular activated carbon (GAC) beds were determined using a fixed-bed reactor system and under conditions typical for swimming pool water treatment. Reaction rates dropped and quasi-stationary conditions were reached quickly. Diffusional mass transport in the pores was shown to be limiting the overall reaction rate. This was reflected consistently in the Thiele Modulus, in the effect of temperature, pore size distribution and of grain size on the reaction rates. Pores
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pore diffusion limits removal of monochloramine in treatment of swimming pool water using granular activated carbon
Water Research, 2017Co-Authors: Bertram Skibinski, Christoph Gotze, Eckhard Worch, Wolfgang UhlAbstract:Overall apparent reaction rates for the removal of monochloramine (MCA) in granular activated carbon (GAC) beds were determined using a fixed-bed reactor system and under conditions typical for swimming pool water treatment. Reaction rates dropped and quasi-stationary conditions were reached quickly. Diffusional mass transport in the pores was shown to be limiting the overall reaction rate. This was reflected consistently in the Thiele Modulus, in the effect of temperature, pore size distribution and of grain size on the reaction rates. Pores <2.5 times the diameter of the monochloramine molecule were shown to be barely accessible for the monochloramine conversion reaction. GACs with a significant proportion of large mesopores were found to have the highest overall reactivity for monochloramine removal.
Jean-pierre Chabriat - One of the best experts on this subject based on the ideXlab platform.
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Dimensionless approach of a polymer electrolyte membrane water electrolysis: Advanced analytical modelling
Journal of Power Sources, 2021Co-Authors: Farid Aubras, Maha Rhandi, Jonathan Deseure, Amangoua Jean-jacques Kadjo, Miloud Bessafi, Jude Majasan, Brigitte Grondin-perez, Florence Druart, Jean-pierre ChabriatAbstract:The water electrolysis appears as a sustainable solution for hydrogen production. The proton exchange membrane electrolyzers (PEM-E) play an increasingly important role in the development of hydrogen technology. Fast analysis of PEM-E efficiency using a mathematical approach is an effective tool for the improvement of these devices. This work presents a closed-form solution of single cell PEM-E modelling. The approach considers charge and mass transport balances. The one-dimensional study focuses on the anodic and the cathodic catalyst layer and the membrane using only dimensionless parameters. The analytical model allows to describe the water management as a function of pressure gradient and current density using a dimensionless ratio of water transport process (ßm). This model is endorsed by experimental data. Dimensionless parameters like Thiele Modulus (ßa,c) or Wagner number (Wa,C) are reached using numerical optimization methods. Changing values of dimensionless numbers, allow the observation of the impact of the two-phase flow regimes on the electrochemical performances.
L Rajendran - One of the best experts on this subject based on the ideXlab platform.
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steady state current in product inhibition kinetics in an amperometric biosensor adomian decomposition and taylor series method
Journal of Electroanalytical Chemistry, 2021Co-Authors: Ramu Usha Rani, L Rajendran, Michael E G LyonsAbstract:Abstract Theoretical models of an amperometric biosensor with product inhibition kinetics are discussed. These models are based on non-stationary diffusion equations containing a non-linear term related to non-Michaelis-Menten kinetics of the enzymatic reaction. The approximate analytical representation of steady-state concentrations is provided for small values Thiele Modulus and all other input variables. Here the Adomian decomposition method and Taylor series method are used to find the analytical expressions for the concentration of substrate, product, current and sensitivity. A comparison of our approximate analytical results with numerical simulation is also presented. A satisfactory agreement is noted. The effect of the parameters Michaelis - Menten constant, inhibition constant and bulk concentration of substrate on the biosensor sensitivity and resistance are discussed.
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Analytical Expressions for Steady-State Concentrations of Substrate and Oxidized and Reduced Mediator in an Amperometric Biosensor
2020Co-Authors: Loghambal Shunmugham, L RajendranAbstract:A mathematical model of modified enzyme-membrane electrode for steady-state condition is discussed. This model contains a nonlinear term related to enzyme kinetics reaction mechanism. The thickness dependence of an amperometric biosensor is presented both analytically and numerically where the biological layer is immobilized between a solid substrate and permeable electrode. The analytical expressions pertaining to the concentration of species and normalized current are obtained using the Adomian decomposition method (ADM). Simple and approximate polynomial expressions of concentrations of an oxidized mediator, substrate, and reduced mediator are derived for all possible values of parameters 2 O (Thiele Modulus), O (normalized surface concentration of oxidized mediator), and S (normalized surface concentration of substrate). A comparison of the analytical approximation and numerical simulation is also presented. A good agreement between theoretical predictions and numerical results is observed
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theoretical analysis of intrinsic reaction kinetics and the behavior of immobilized enzymes system for steady state conditions
Biochemical Engineering Journal, 2014Co-Authors: T Praveen, Pedro Valencia, L RajendranAbstract:Abstract Mathematical modeling of immobilized enzymes under different kinetics mechanism viz. simple Michaelis–Menten, uncompetitive substrate inhibition, total competitive product inhibition, total non-competitive product inhibition and reversible Michaelis–Menten reaction are discussed. These five kinetic models are based on reaction diffusion equations containing non-linear terms related to Michaelis–Menten kinetics of the enzymatic reaction. Modified Adomian decomposition method is employed to derive the general analytical expressions of substrate and product concentration for all these five mechanisms for all possible values of the parameters ΦS (Thiele Modulus for substrate), ΦP (Thiele Modulus for product) and α (dimensionless inhibition degree). Also we have presented the general analytical expressions for the mean integrated effectiveness factor for all values of parameters. Analytical results are compared with the numerical results and also with the limiting case results, which are found to be good in agreement.
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analysis of a ph based potentiometric biosensor using the homotopy perturbation method
Chemical Engineering & Technology, 2010Co-Authors: Athimoolam Meena, L RajendranAbstract:A mathematical model of steady-state and non-steady-state responses of a pH-based potentiometric biosensor immobilizing organophosphorus hydrolase was developed. The model is based on non-stationary diffusion equations containing a nonlinear term related to the Michaelis-Menten kinetics of an enzymatic reaction. An analytical expression for the substrate concentration was obtained for all values of parameter a (Thiele Modulus) using the homotopy perturbation method. From this result, the concentrations of the deprotonation products of an organophosphodiester (PhH, ZH and AH) were obtained. Our analytical results were compared with available simulation results. A satisfactory agreement with the simulation data is noted.
Bertram Skibinski - One of the best experts on this subject based on the ideXlab platform.
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Pore diffusion limits removal of monochloramine in treatment of swimming pool water using granular activated carbon.
Water Research, 2018Co-Authors: Bertram Skibinski, Christoph Gotze, Eckhard Worch, Wolfgang UhlAbstract:Overall apparent reaction rates for the removal of monochloramine (MCA) in granular activated carbon (GAC) beds were determined using a fixed-bed reactor system and under conditions typical for swimming pool water treatment. Reaction rates dropped and quasi-stationary conditions were reached quickly. Diffusional mass transport in the pores was shown to be limiting the overall reaction rate. This was reflected consistently in the Thiele Modulus, in the effect of temperature, pore size distribution and of grain size on the reaction rates. Pores
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pore diffusion limits removal of monochloramine in treatment of swimming pool water using granular activated carbon
Water Research, 2017Co-Authors: Bertram Skibinski, Christoph Gotze, Eckhard Worch, Wolfgang UhlAbstract:Overall apparent reaction rates for the removal of monochloramine (MCA) in granular activated carbon (GAC) beds were determined using a fixed-bed reactor system and under conditions typical for swimming pool water treatment. Reaction rates dropped and quasi-stationary conditions were reached quickly. Diffusional mass transport in the pores was shown to be limiting the overall reaction rate. This was reflected consistently in the Thiele Modulus, in the effect of temperature, pore size distribution and of grain size on the reaction rates. Pores <2.5 times the diameter of the monochloramine molecule were shown to be barely accessible for the monochloramine conversion reaction. GACs with a significant proportion of large mesopores were found to have the highest overall reactivity for monochloramine removal.
Farid Aubras - One of the best experts on this subject based on the ideXlab platform.
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Dimensionless approach of a polymer electrolyte membrane water electrolysis: Advanced analytical modelling
Journal of Power Sources, 2021Co-Authors: Farid Aubras, Maha Rhandi, Jonathan Deseure, Amangoua Jean-jacques Kadjo, Miloud Bessafi, Jude Majasan, Brigitte Grondin-perez, Florence Druart, Jean-pierre ChabriatAbstract:The water electrolysis appears as a sustainable solution for hydrogen production. The proton exchange membrane electrolyzers (PEM-E) play an increasingly important role in the development of hydrogen technology. Fast analysis of PEM-E efficiency using a mathematical approach is an effective tool for the improvement of these devices. This work presents a closed-form solution of single cell PEM-E modelling. The approach considers charge and mass transport balances. The one-dimensional study focuses on the anodic and the cathodic catalyst layer and the membrane using only dimensionless parameters. The analytical model allows to describe the water management as a function of pressure gradient and current density using a dimensionless ratio of water transport process (ßm). This model is endorsed by experimental data. Dimensionless parameters like Thiele Modulus (ßa,c) or Wagner number (Wa,C) are reached using numerical optimization methods. Changing values of dimensionless numbers, allow the observation of the impact of the two-phase flow regimes on the electrochemical performances.
