The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Mario Bergeron - One of the best experts on this subject based on the ideXlab platform.
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Zinc removal from dilute solutions using a Rotating Cylinder electrode reactor
Journal of Applied Electrochemistry, 1996Co-Authors: Jean Pierre, Normand Massé, É. Fréchette, Mario BergeronAbstract:Mine residue recycling processes produce dilute zinc solutions suitable for metal recovery. The Rotating Cylinder electrode reactor behaviour sequentially followed charge transfer and diffusion control mechanisms, even with solutions contaminated with metals or organic substances. Zinc removal at low pH (∼0) and low concentration (∼2 mg dm^−3) is demonstrated. Under galvanostatic operation, the zinc deposition current efficiency in the charge transfer control region attains values up to 77.3%, whereas in the diffusion control region it decreases rapidly to values as low as 0.1%. When a potentio-static mode is used, less energy is required to deposit zinc, even at low current efficiency. The results and possible problems for continuous reactor operation under conditions of powder formation are identified and discussed using knowledge from other zinc industries such as electrowinning, plating and batteries.
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Dissolved oxygen concentration in an undivided Rotating Cylinder electrode reactor
Electrochimica Acta, 1994Co-Authors: Jean Pierre, Normand Massé, Mario BergeronAbstract:The steady state mass balance for dissolved oxygen in an undivided Rotating Cylinder electrode reactor was established. Cases involving the absence or presence of diffusion controlled oxygen reduction reaction were treated. The results show that in the absence of the oxygen reduction reaction and under low electrolyte velocities employed industrially, the Rotating Cylinder electrode reactor, exhibiting a continuous stirred tank reactor behaviour, yields lower dissolved gas concentrations than a plug flow reactor. Therefore, the Rotating Cylinder electrode reactor leads to lower redissolution rates of the detached metallic particles by oxygen corrosion. The effect of the dissolved gas concentration in the inlet electrolyte also demonstrates the benefits of a prior degassing step in the flow sheet. The simpler equation derived in the absence of oxygen reduction may be used in its presence for inlet dissolved oxygen concentrations below saturation and industrially relevant electrolyte velocities ranging from approx. 0 to 0.3 m s−1 if metal deposition current efficiency is higher than 87% or, conversely, if the dissolved metal concentration to dissolved oxygen concentration ratio is greater than 27. An even simpler equation based on the added hypothesis of total desorption of the gas produced can also be used with electrolyte velocities below 0.025 m s−1. Finally, the derived equations allow optimization of the Rotating Cylinder electrode reactor.
Jean Pierre - One of the best experts on this subject based on the ideXlab platform.
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Zinc removal from dilute solutions using a Rotating Cylinder electrode reactor
Journal of Applied Electrochemistry, 1996Co-Authors: Jean Pierre, Normand Massé, É. Fréchette, Mario BergeronAbstract:Mine residue recycling processes produce dilute zinc solutions suitable for metal recovery. The Rotating Cylinder electrode reactor behaviour sequentially followed charge transfer and diffusion control mechanisms, even with solutions contaminated with metals or organic substances. Zinc removal at low pH (∼0) and low concentration (∼2 mg dm^−3) is demonstrated. Under galvanostatic operation, the zinc deposition current efficiency in the charge transfer control region attains values up to 77.3%, whereas in the diffusion control region it decreases rapidly to values as low as 0.1%. When a potentio-static mode is used, less energy is required to deposit zinc, even at low current efficiency. The results and possible problems for continuous reactor operation under conditions of powder formation are identified and discussed using knowledge from other zinc industries such as electrowinning, plating and batteries.
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Dissolved oxygen concentration in an undivided Rotating Cylinder electrode reactor
Electrochimica Acta, 1994Co-Authors: Jean Pierre, Normand Massé, Mario BergeronAbstract:The steady state mass balance for dissolved oxygen in an undivided Rotating Cylinder electrode reactor was established. Cases involving the absence or presence of diffusion controlled oxygen reduction reaction were treated. The results show that in the absence of the oxygen reduction reaction and under low electrolyte velocities employed industrially, the Rotating Cylinder electrode reactor, exhibiting a continuous stirred tank reactor behaviour, yields lower dissolved gas concentrations than a plug flow reactor. Therefore, the Rotating Cylinder electrode reactor leads to lower redissolution rates of the detached metallic particles by oxygen corrosion. The effect of the dissolved gas concentration in the inlet electrolyte also demonstrates the benefits of a prior degassing step in the flow sheet. The simpler equation derived in the absence of oxygen reduction may be used in its presence for inlet dissolved oxygen concentrations below saturation and industrially relevant electrolyte velocities ranging from approx. 0 to 0.3 m s−1 if metal deposition current efficiency is higher than 87% or, conversely, if the dissolved metal concentration to dissolved oxygen concentration ratio is greater than 27. An even simpler equation based on the added hypothesis of total desorption of the gas produced can also be used with electrolyte velocities below 0.025 m s−1. Finally, the derived equations allow optimization of the Rotating Cylinder electrode reactor.
Normand Massé - One of the best experts on this subject based on the ideXlab platform.
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Zinc removal from dilute solutions using a Rotating Cylinder electrode reactor
Journal of Applied Electrochemistry, 1996Co-Authors: Jean Pierre, Normand Massé, É. Fréchette, Mario BergeronAbstract:Mine residue recycling processes produce dilute zinc solutions suitable for metal recovery. The Rotating Cylinder electrode reactor behaviour sequentially followed charge transfer and diffusion control mechanisms, even with solutions contaminated with metals or organic substances. Zinc removal at low pH (∼0) and low concentration (∼2 mg dm^−3) is demonstrated. Under galvanostatic operation, the zinc deposition current efficiency in the charge transfer control region attains values up to 77.3%, whereas in the diffusion control region it decreases rapidly to values as low as 0.1%. When a potentio-static mode is used, less energy is required to deposit zinc, even at low current efficiency. The results and possible problems for continuous reactor operation under conditions of powder formation are identified and discussed using knowledge from other zinc industries such as electrowinning, plating and batteries.
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Dissolved oxygen concentration in an undivided Rotating Cylinder electrode reactor
Electrochimica Acta, 1994Co-Authors: Jean Pierre, Normand Massé, Mario BergeronAbstract:The steady state mass balance for dissolved oxygen in an undivided Rotating Cylinder electrode reactor was established. Cases involving the absence or presence of diffusion controlled oxygen reduction reaction were treated. The results show that in the absence of the oxygen reduction reaction and under low electrolyte velocities employed industrially, the Rotating Cylinder electrode reactor, exhibiting a continuous stirred tank reactor behaviour, yields lower dissolved gas concentrations than a plug flow reactor. Therefore, the Rotating Cylinder electrode reactor leads to lower redissolution rates of the detached metallic particles by oxygen corrosion. The effect of the dissolved gas concentration in the inlet electrolyte also demonstrates the benefits of a prior degassing step in the flow sheet. The simpler equation derived in the absence of oxygen reduction may be used in its presence for inlet dissolved oxygen concentrations below saturation and industrially relevant electrolyte velocities ranging from approx. 0 to 0.3 m s−1 if metal deposition current efficiency is higher than 87% or, conversely, if the dissolved metal concentration to dissolved oxygen concentration ratio is greater than 27. An even simpler equation based on the added hypothesis of total desorption of the gas produced can also be used with electrolyte velocities below 0.025 m s−1. Finally, the derived equations allow optimization of the Rotating Cylinder electrode reactor.
J.m. Grau - One of the best experts on this subject based on the ideXlab platform.
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Mass-transfer studies at Rotating Cylinder electrodes with turbulence promoters
Chemical Engineering and Processing: Process Intensification, 2011Co-Authors: J.m. Grau, Jose Maria BisangAbstract:Abstract Mass transfer was studied at a Rotating Cylinder electrode with different turbulence promoters using the reduction of ferricyanide as a test reaction. Four types of turbulence promoters were examined: expanded plastic meshes, Teflon structures, a plastic woven mesh and a plastic perforated net, which were rotated together with the electrode. The best performance was obtained for the Teflon structures at low rotation speeds and for the plastic woven mesh at high rotation speeds. The effect of both the length and the number of sheets of the turbulence promoters as well as the use of static promoters were also analysed. Comparisons of mass-transfer performance of turbulence promoters are made with other three-dimensional structures. The mass-transfer enhancement factor related to a smooth Rotating Cylinder electrode is twice as large.
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Electrochemical removal of cadmium from dilute aqueous solutions using a Rotating Cylinder electrode of wedge wire screens
Journal of Applied Electrochemistry, 2007Co-Authors: J.m. Grau, J.m. BisangAbstract:Rates of mass transfer at Rotating Cylinder electrodes of wedge wire screens were studied by measuring the limiting current for the cathodic reduction of ferricyanide as test reaction. The experimental data are well correlated by an empirical expression between the Sherwood number and the Reynolds number, both in terms of the internal slot opening as characteristic length, and including two additional dimensionless parameters in order to characterize the geometry of the screens. The performance of an undivided electrochemical batch reactor with a Rotating Cylinder cathode of wedge wire screens was tested analyzing the cadmium removal from dilute solutions. The effect of cathodic applied potential and size of the screen is studied. Taking into account the residual cadmium concentration the best results were obtained for a cathode potential of −1.1 V vs. SCE at 700 rpm, where the cadmium concentration decreased from 54 to 0.9 mg l^−1 after 30 min of electrolysis with a specific energy consumption of 10.7 kWh kg^−1 and a normalized space velocity of 3.54 h^−1.
Bruno H. Zimm - One of the best experts on this subject based on the ideXlab platform.
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Rotating Cylinder viscometers.
Methods in Enzymology, 2004Co-Authors: Elliott L. Uhlenhopp, Bruno H. ZimmAbstract:Publisher Summary The floating rotor viscometer has found widespread use for studying the viscosity of deoxyribonucleic acid (DNA) solutions under conditions of low shear and for examining different types of non-Newtonian behavior, such as the increase or decrease in viscosity with change in shearing force or time of shear. In the past few years, this viscometer has also been used to study the shear-dependent viscosity of certain protein solutions. The viscosity of a solution, measured in poises, is simply the ratio of the shear stress exerted on the solution, in dynes/cm 2 , divided by the shear rate, in sec –1 . Rotating Cylinder viscometers can either fix the shear stress and measure the shear rate or fix the shear rate and measure the shear stress. The latter type includes viscometers where either the inner or the outer Cylinder is rotated, and the stress on the opposing Cylinder is measured directly. These viscometers are usually complicated in construction and are designed for specific applications. Some incorporate a guard ring for circumventing the problem of surface films when working with protein-containing solutions. Others measure the rheological properties of blood by providing special geometries so that normal stresses and time-dependent phenomena can be investigated.
