The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
François Renard - One of the best experts on this subject based on the ideXlab platform.
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of t...
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of the coherent domain average size r (nm) with reaction time t (s). Then, a kinetic pseudo-second-order model was satisfactory used to fit the experimental−calculated data and determine the linear growth initial rate of submicrometric calcite. The results showed that the values of linear growth rate of calcite were equivalents for both Systems, i.e., 0.14 nm/s at 30 °C and 55 bar and 0.12 nm/s at 90 °C and 90 bar. However, the average size of calcite crystals, here expressed as a maximum of coherent domain average size, was clearly higher at 90 °C and 90 bar (174 nm) than at 30 °C and 55 bar (63 nm). The main advantage for this method is the possibility to estimate the linear growth rate of crystalline fine particles (>40 nm) growing in triphasic gas−Liquid−Solid Systems. Here, it is considered that depressurization of cell reaction has insignificant physicochemical effect on the Solid precipitates; obviously, this is not the case for the interacting solutions.
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Removal of oxyanions from synthetic wastewater via carbonation process of calcium hydroxide: Applied and fundamental aspects
Journal of Hazardous Materials, 2009Co-Authors: German Montes-hernandez, François Renard, Nicolas Concha Lozano, Eric QuiricoAbstract:Removal of oxyanions (selenite, selenate, arsenate, phosphate and nitrate) during calcite formation was experimentally studied using aqueous carbonation of calcium hydroxide under moderate pressure (PCO2∼= 20 bar) and temperature (30 ◦C). The effects of Ca(OH)2 dose (10 and 20 g), Ca(OH)2 source (commercial pure material or alkaline paper mill waste) and oxyanion initial concentration (from 0 to 70mgatom/L) were investigated for this anisobaric gas–Liquid–Solid System. The Ca(OH)2 carbonation reaction allowed successfully the removal of selenite (>90%), arsenate (>78%) and phosphate (∼= 100%) from synthetic solutions. Conversely, nitrate and selenate had not any physicochemical affinity/effect during calcite formation. The rate of CO2 transfer during calcite formation in presence of oxyanions was equal or slower than for an oxyanion-free System, allowing to define a retarding kinetic factor RF that can vary between 0 (no retarding effect) to 1 (total inhibition). For selenite and phosphate RF was quite high, close to 0.3. A small retarding effect was detected for arsenate (RF≈0.05) and no retarding effect was detected for selenate and nitrate (RF≈0). In general, RF depends on the oxyanion initial concentration, oxyanion nature and Ca(OH)2 dose. The presence of oxyanions could also influence the crystal morphology and aggregation/agglomeration process. For example, a c-axis elongation of calcite crystals was clearly observed at the equilibrium, for calcite formation in presence of selenite and phosphate. The oxyanions removal process proposed herein was inspired on the common physicochemical treatment of wastewater using calcium hydroxide (Ca(OH)2). The particularity, for this novel method is the simultaneous calcium hydroxide carbonation with compressed carbon dioxide in order to stabilise the Solid matter. This economical and ecological method could allowthe removal of various oxyanions aswell as the ex situ mineral sequestration of CO2; particularly, when the Ca(OH)2 source comes from alkaline Solid waste.
X Y Huang - One of the best experts on this subject based on the ideXlab platform.
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thermodynamics modeling for moving contact line in gas Liquid Solid System capillary rise problem revisited
Physics of Fluids, 2001Co-Authors: X Y HuangAbstract:The nonequilibrium thermodynamics framework is tailored in the present paper to formulate the gas/Liquid/Solid System. In this System, there are two important issues, namely, the contact line motion and contact angle change, and shear stress singularity, during the dynamic evolution. Traditionally, the fluid mechanics approach has been applied to model these two issues. In the present paper, we applied a thermodynamics formulation to re-examine the first issue, i.e., the dynamic motion of the contact line and angle. It provides a new angle to understand the fundamentals of this classical problem. In order to verify the reliability of the present thermodynamics formulation, the capillary rise problem is revisited by using the formulation. A numerical result obtained based on the thermodynamics formulation is then compared with experimental test data. Excellent agreement between our analytical and experimental results gives us confidence for the future works on this approach.
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Thermodynamics modeling for moving contact line in gas/Liquid/Solid System: Capillary rise problem revisited
Physics of Fluids, 2001Co-Authors: Hui Fan, Y. X. Gao, X Y HuangAbstract:The nonequilibrium thermodynamics framework is tailored in the present paper to formulate the gas/Liquid/Solid System. In this System, there are two important issues, namely, the contact line motion and contact angle change, and shear stress singularity, during the dynamic evolution. Traditionally, the fluid mechanics approach has been applied to model these two issues. In the present paper, we applied a thermodynamics formulation to re-examine the first issue, i.e., the dynamic motion of the contact line and angle. It provides a new angle to understand the fundamentals of this classical problem. In order to verify the reliability of the present thermodynamics formulation, the capillary rise problem is revisited by using the formulation. A numerical result obtained based on the thermodynamics formulation is then compared with experimental test data. Excellent agreement between our analytical and experimental results gives us confidence for the future works on this approach.
German Montes-hernandez - One of the best experts on this subject based on the ideXlab platform.
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of t...
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of the coherent domain average size r (nm) with reaction time t (s). Then, a kinetic pseudo-second-order model was satisfactory used to fit the experimental−calculated data and determine the linear growth initial rate of submicrometric calcite. The results showed that the values of linear growth rate of calcite were equivalents for both Systems, i.e., 0.14 nm/s at 30 °C and 55 bar and 0.12 nm/s at 90 °C and 90 bar. However, the average size of calcite crystals, here expressed as a maximum of coherent domain average size, was clearly higher at 90 °C and 90 bar (174 nm) than at 30 °C and 55 bar (63 nm). The main advantage for this method is the possibility to estimate the linear growth rate of crystalline fine particles (>40 nm) growing in triphasic gas−Liquid−Solid Systems. Here, it is considered that depressurization of cell reaction has insignificant physicochemical effect on the Solid precipitates; obviously, this is not the case for the interacting solutions.
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Removal of oxyanions from synthetic wastewater via carbonation process of calcium hydroxide: Applied and fundamental aspects
Journal of Hazardous Materials, 2009Co-Authors: German Montes-hernandez, François Renard, Nicolas Concha Lozano, Eric QuiricoAbstract:Removal of oxyanions (selenite, selenate, arsenate, phosphate and nitrate) during calcite formation was experimentally studied using aqueous carbonation of calcium hydroxide under moderate pressure (PCO2∼= 20 bar) and temperature (30 ◦C). The effects of Ca(OH)2 dose (10 and 20 g), Ca(OH)2 source (commercial pure material or alkaline paper mill waste) and oxyanion initial concentration (from 0 to 70mgatom/L) were investigated for this anisobaric gas–Liquid–Solid System. The Ca(OH)2 carbonation reaction allowed successfully the removal of selenite (>90%), arsenate (>78%) and phosphate (∼= 100%) from synthetic solutions. Conversely, nitrate and selenate had not any physicochemical affinity/effect during calcite formation. The rate of CO2 transfer during calcite formation in presence of oxyanions was equal or slower than for an oxyanion-free System, allowing to define a retarding kinetic factor RF that can vary between 0 (no retarding effect) to 1 (total inhibition). For selenite and phosphate RF was quite high, close to 0.3. A small retarding effect was detected for arsenate (RF≈0.05) and no retarding effect was detected for selenate and nitrate (RF≈0). In general, RF depends on the oxyanion initial concentration, oxyanion nature and Ca(OH)2 dose. The presence of oxyanions could also influence the crystal morphology and aggregation/agglomeration process. For example, a c-axis elongation of calcite crystals was clearly observed at the equilibrium, for calcite formation in presence of selenite and phosphate. The oxyanions removal process proposed herein was inspired on the common physicochemical treatment of wastewater using calcium hydroxide (Ca(OH)2). The particularity, for this novel method is the simultaneous calcium hydroxide carbonation with compressed carbon dioxide in order to stabilise the Solid matter. This economical and ecological method could allowthe removal of various oxyanions aswell as the ex situ mineral sequestration of CO2; particularly, when the Ca(OH)2 source comes from alkaline Solid waste.
Krishna D.p. Nigam - One of the best experts on this subject based on the ideXlab platform.
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Liquid distribution studies in trickle-bed reactors
Chemical Engineering Science, 2001Co-Authors: Arunabha Kundu, Anil K. Saroha, Krishna D.p. NigamAbstract:Liquid distribution plays an important role in determining the reactor performance in a trickle-bed reactor. Radial Liquid distribution was studied in a trickle-bed reactor with five different shapes and sizes of catalyst packing in a uniformly distributed Liquid inlet. The Liquid tends to flow preferentially along the existing filaments where the porosity is high. The introduction of gas flow into the Liquid–Solid System smoothens the Liquid distribution to some extent due to the competition between Liquid and gas phases for the interstitial pore space.
Alejandro Fernandez-martinez - One of the best experts on this subject based on the ideXlab platform.
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of t...
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Novel Method to Estimate the Linear Growth Rate of Submicrometric Calcite Produced in a Triphasic Gas−Liquid−Solid System
Crystal Growth & Design, 2009Co-Authors: German Montes-hernandez, Alejandro Fernandez-martinez, François RenardAbstract:The linear growth rate is an essential parameter to describe and simulate the crystal growth processes of Solid materials. Concerning the calcite mineral, indirect methods (by depletion of calcium concentration) and direct methods (ex. using microscopic measurements) have been reported in the literature. Here, homogeneous (solution−solution) or heterogeneous (solution−Solid) Systems are Systematically considered. Conversely, the estimation of linear growth rate of calcite for the triphasic gas−Liquid−Solid Systems under high gas pressure and temperature has not been reported in the literature to the best of our knowledge. In the present study, we propose a new method to estimate the linear growth initial rate of submicrometric calcite produced in a triphasic gas−Liquid−Solid System under high gas pressure (55 and 90 bar) and moderated to high temperature (30 and 90 °C) by using Rietveld refinements of X-ray diffraction (XRD) patterns. These Rietveld refinements allowed the estimation on the variation of the coherent domain average size r (nm) with reaction time t (s). Then, a kinetic pseudo-second-order model was satisfactory used to fit the experimental−calculated data and determine the linear growth initial rate of submicrometric calcite. The results showed that the values of linear growth rate of calcite were equivalents for both Systems, i.e., 0.14 nm/s at 30 °C and 55 bar and 0.12 nm/s at 90 °C and 90 bar. However, the average size of calcite crystals, here expressed as a maximum of coherent domain average size, was clearly higher at 90 °C and 90 bar (174 nm) than at 30 °C and 55 bar (63 nm). The main advantage for this method is the possibility to estimate the linear growth rate of crystalline fine particles (>40 nm) growing in triphasic gas−Liquid−Solid Systems. Here, it is considered that depressurization of cell reaction has insignificant physicochemical effect on the Solid precipitates; obviously, this is not the case for the interacting solutions.