Inverting stop-flow leaching experiments and detection of physical and chemical non-equilibria

2020 ◽  
Author(s):  
Lian Zhou ◽  
Laurent Lassabatere ◽  
Khalil Hanna
Keyword(s):  
Experimental Data ◽  
Breakthrough Curves ◽  
Water Fraction ◽  
Mobile Water ◽  
Immobile Water ◽  
Leaching Experiments ◽  
Water Fractions ◽  
Physical And Chemical ◽  
Flow Experiments ◽  
Stop Flow

<p>Flow heterogeneity strongly impacts mass transport. In particular, the presence of water fractionation into mobile and immobile water fractions may affect pollutant sorption to soil particles. Indeed, before sorbing, the pollutants need to diffuse from mobile water to immobile water fractions. In a previous study, we investigated the possibility of stop-flow experiments for the detection of physical and chemical non-equilibria. A sensitivity analysis proved that it was possible to detect the two types of non-equilibria. The effect of parameters related to physical  (mobile water fraction and solute exchange rate)  and chemical (chemical kinetics) non-equilibria were varied and related impacts on the shape of the breakthrough curves were characterized for stop-flow experiments. However, the feasibility of inverting procedures was not investigated at all. In particular, the estimation of these parameters by fitting the model to real experimental data (with noise) may be feasible but may also bring some uncertainty with biased and non-unique estimates. In this study, using both numerically generated data and experimental data, we characterize the estimate uncertainty and equifinality. This study will help in optimizing the inverting procedure for the design of more robust and less biased estimates and the quantification of physical and chemical non-equilibria parameters.</p>

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

Field measured mobile water fraction for soils of contrasting texture

Soil Research ◽  
2000 ◽  
Vol 38 (6) ◽  
pp. 1131 ◽  
Author(s):  
A. E. A. Okom ◽  
R. E. White ◽  
L. K. Heng
Keyword(s):  
Hydraulic Conductivity ◽  
Solute Transport ◽  
Water Content ◽  
Time Scale ◽  
Solute Transfer ◽  
Water Fraction ◽  
Mobile Water ◽  
Immobile Water ◽  
Mobile Fraction ◽  
Fertiliser Application

For the purpose of modeling solute transport, soil water has often been simply divided into an essentially mobile fraction, q m , which is active in solute transport, and an apparently immobile fraction, q im . Distinction between q m and q im was sought using the disc permeameter technique. This study examines unsaturated estimates of mobile water content at suction heads, h, of 20, 40, 80, and 120 mm for several soils ranging in texture from sand to clay. Following infiltration of 35 mm depth of 0.01 M KBr into initially dry soils, soil samples were collected from below the base of the disc permeameter and analysed for tracer concentrations which enabled partitioning of mobile and immobile water. Hydraulic conductivity and sorptivity were also derived from the infiltration data. The results show the expected non-linearity of hydraulic conductivity and sorptivity with suction. The mobile water expressed as a fraction, f, of the volumetric water content q (f = q m / q ) was generally found to range from 0.7 to 0.95, with an average of 0.85. The exception was one site for which f was ª 0.50. These values of f are comparable to those derived from leaching studies reported in the literature. An important finding of this work is that within the range of suctions measured, the mobile fraction was independent of suction. A possible explanation for this observation is that the soil capillary forces were dominant during the time scale of the experiment and therefore rapidly drew the invading solution. This finding could have important implications for fertiliser application. Furthermore, this result suggests that the assumption of a negligible solute transfer coefficient, a , between the mobile and immobile domains may be valid within the time scale of this method of measuring the mobile water content.

Biochar caged zirconium ferrite nanocomposites for the adsorptive removal of Reactive Blue 19 dye in a batch and column reactors and conditions optimizaton

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shazia Perveen ◽  
Raziya Nadeem ◽  
Shaukat Ali ◽  
Yasir Jamil
Keyword(s):  
Experimental Data ◽  
Low Dose ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Adsorption Efficiency ◽  
Fixed Bed Column ◽  
Flow Rates ◽  
Adsorptive Removal ◽  
Reactive Blue 19 ◽  
Pseudo Second Order

Abstract Biochar caged zirconium ferrite (BC-ZrFe2O5) nanocomposites were fabricated and their adsorption capacity for Reactive Blue 19 (RB19) dye was evaluated in a fixed-bed column and batch sorption mode. The adsorption of dye onto BC-ZrFe2O5 NCs followed pseudo-second-order kinetics (R 2 = 0.998) and among isotherms, the experimental data was best fitted to Sips model as compared to Freundlich and Langmuir isotherms models. The influence of flow-rate (3–5 mL min−1), inlet RB19 dye concentration (20–100 mg L−1) and quantity of BC-ZrFe2O5 NCs (0.5–1.5 g) on fixed-bed sorption was elucidated by Box-Behnken experimental design. The saturation times (C t /C o  = 0.95) and breakthrough (C t /C o  = 0.05) were higher at lower flow-rates and higher dose of BC-ZrFe2O5 NCs. The saturation times decreased, but breakthrough was increased with the initial RB19 dye concentration. The treated volume was higher at low sorbent dose and influent concentration. Fractional bed utilization (FBU) increased with RB19 dye concentration and flow rates at low dose of BC-ZrFe2O5 NCs. Yan model was fitted best to breakthrough curves data as compared to Bohart-Adams and Thomas models. Results revealed that BC-ZrFe2O5 nanocomposite has promising adsorption efficiency and could be used for the adsorption of dyes from textile effluents.

scholarly journals Research on the viscosity of stabilized emulsions in different pipe diameters using pressure drop and phase inversion

2021 ◽  
Author(s):  
Jose Plasencia ◽  
Nathanael Inkson ◽  
Ole Jørgen Nydal
Keyword(s):  
Pressure Drop ◽  
Salt Water ◽  
Flow Behavior ◽  
Turbulent Viscosity ◽  
Relative Viscosity ◽  
Cfd Modeling ◽  
Water Fraction ◽  
Water Fractions ◽  
Oil Emulsions ◽  
Mixture Velocity

AbstractThis paper reports experimental research on the flow behavior of oil-water surfactant stabilized emulsions in different pipe diameters along with theoretical and computational fluid dynamics (CFD) modeling of the relative viscosity and inversion properties. The pipe flow of emulsions was studied in turbulent and laminar conditions in four pipe diameters (16, 32, 60, and 90 mm) at different mixture velocities and increasing water fractions. Salt water (3.5% NaCl w/v, pH = 7.3) and a mineral oil premixed with a lipophilic surfactant (Exxsol D80 + 0.25% v/v of Span 80) were used as the test fluids. The formation of water-in-oil emulsions was observed from low water fractions up to the inversion point. After inversion, unstable water-in-oil in water multiple emulsions were observed under different flow regimes. These regimes depend on the mixture velocity and the local water fraction of the water-in-oil emulsion. The eddy turbulent viscosity calculated using an elliptic-blending k-ε model and the relative viscosity in combination act to explain the enhanced pressure drop observed in the experiments. The inversion process occurred at a constant water fraction (90%) and was triggered by an increase of mixture velocity. No drag reduction effect was detected for the water-in-oil emulsions obtained before inversion.

scholarly journals A mesoscopic model for compression of granular materials

2018 ◽  
Vol 183 ◽  
pp. 01054
Author(s):  
Elisha Rejovitzky
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Granular Materials ◽  
Mechanical Model ◽  
Sound Speed ◽  
Bulk Material ◽  
High Sensitivity ◽  
Water Fraction ◽  
Protective Structures ◽  
Solid Spheres

The design of protective structures often requires numerical modeling of shock-wave propagation in the surrounding soils. Properties of the soil such as grain-grading and water-fraction may vary spatially around a structure and among different sites. To better understand how these properties affect wave propagation we study how the meso-structure of soils affects their equation of state (EOS). In this work we present a meso-mechanical model for granular materials based on a simple representation of the grains as solid spheres. Grain-grading is prescribed, and a packing algorithm is used to obtain periodic grain morphologies of tightly packed randomly distributed spheres. The model is calibrated by using experimental data of sand compaction and sound-speed measurements from the literature. We study the effects of graingrading and show that the pressures at low strains exhibit high sensitivity to the level of connectivity between grains. At high strains, the EOS of the bulk material of the grains dominates the behavior of the EOS of the granular material.

scholarly journals Characterization of Spent Ni-MH Batteries

2012 ◽  
Vol 730-732 ◽  
pp. 569-574
Author(s):  
Marta Cabral ◽  
Fernanda Margarido ◽  
Carlos A. Nogueira
Keyword(s):  
Quantitative Analysis ◽  
Electrode Materials ◽  
Phase Identification ◽  
Recycling Process ◽  
X Ray ◽  
Leaching Experiments ◽  
Plastic Components ◽  
Definition Of ◽  
Physical And Chemical

Spent Ni-MH batteries are not considered too dangerous for the environment, but they have a considerable economical value due to the chemical composition of electrodes which are highly concentrated in metals. The present work aimed at the physical and chemical characterisation of spent cylindrical and thin prismatic Ni-MH batteries, contributing for a better definition of the recycling process of these spent products. The electrode materials correspond to more than 50% of the batteries weight and contain essentially nickel and rare earths (RE), and other secondary elements (Co, Mn, Al). The remaining components are the steel parts from the external case and supporting grids (near 30%) containing Fe and Ni, and the plastic components (<10%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. Phase identification by X-ray powder diffraction combined with chemical analysis and leaching experiments allowed advancing the electrode materials composition. The cathode is essentially constituted by 6% metallic Ni, 66% Ni(OH)2, 4.3% Co(OH)2 and the anode consists mainly in 62% RENi5 and 17% of substitutes and/or additives such as Co, Mn and Al.

Effect of reaction-rate on leaching of phosphate through sandy soils of Western-Australia

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 211 ◽  
Author(s):  
RG Gerritse
Keyword(s):  
Computer Simulation ◽  
Reaction Rate ◽  
Empirical Equation ◽  
Sandy Soils ◽  
Breakthrough Curves ◽  
Computer Simulation Model ◽  
Input Concentration ◽  
Flow Rates ◽  
Field Situation ◽  
Leaching Experiments

The effect of reaction rate on the mobility of phosphate in soils was measured from breakthrough curves in the leachate from small columns of soil, following step increases in the input concentration of phosphate. Average mobilities of phosphate in columns of soil, following a step increase in the input concentration, decrease with decreasing rate of flow and with increasing distance travelled and appear to be linearly correlated on a log-log scale with both flow rate and distance travelled. An empirical equation, describing these relationships, fits data from leaching experiments at flow rates between 30 and 600 cm/day in columns of soil ~10-30 cm in length. Two coefficients are required and are obtained by curve fitting breakthrough curves, calculated with a numerical computer simulation model, to experimental breakthrough curves. The fitted equation enables extrapolation to flow rates and distances travelled that are more relevant to a field situation.

scholarly journals Adsorption of propan-1-ol vapour on Sorbonorit 4 activated carbon – equilibrium and dynamic studies

2017 ◽  
Vol 19 (4) ◽  
pp. 59-64 ◽  
Author(s):  
Dorota Downarowicz ◽  
Katarzyna Ziętarska
Keyword(s):  
Experimental Data ◽  
Activated Carbon ◽  
Energy Requirement ◽  
Isosteric Heat ◽  
Breakthrough Curves ◽  
Isotherm Models ◽  
Column Studies ◽  
Temperature Isotherm ◽  
Electrothermal Desorption ◽  
Temperature Swing Adsorption

Abstract The study examined the adsorption of propan-1-ol (1PN) vapour on Sorbonorit 4 (S4) activated carbon in cyclic Electrothermal Temperature Swing Adsorption (ETSA) process. Dynamic adsorption capacity and breakthrough time were determined based on column studies. Thomas model was used to describe experimental breakthrough curves. Adsorption isotherms for 1PN vapour on S4 activated carbon were tested at 293 to 413 K. The experimental data were examined by using three multi-temperature isotherm models: Toth, Sips and hybrid Langmuir-Sips. Results indicate that S4 activated carbon is a heterogeneous adsorbent and the hybrid Langmuir-Sips model provides the best-fit experimental data. The energy requirement for 1PN electrothermal desorption from S4 bed (ca. 170–200 kJ/mol) was about 3 to 3.5 times larger than the isosteric heat of adsorption (56.8 kJ/mol), which was calculated using Toth adsorption isotherm.

scholarly journals Evolution of the Reaction and Alteration of Mudstone with Ordinary Portland Cement Leachates: Sequential Flow Experiments and Reactive-Transport Modelling

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1026
Author(s):  
Keith Bateman ◽  
Shota Murayama ◽  
Yuji Hanamachi ◽  
James Wilson ◽  
Takamasa Seta ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Chemical Properties ◽  
Reactive Transport Modelling ◽  
Transport Modelling ◽  
General Sequence ◽  
Long Term Performance ◽  
Term Performance ◽  
Physical And Chemical ◽  
Flow Experiments

The construction of a repository for geological disposal of radioactive waste will include the use of cement-based materials. Following closure, groundwater will saturate the repository and the extensive use of cement will result in the development of a highly alkaline porewater, pH > 12.5; this fluid will migrate into and react with the host rock. The chemistry of the fluid will evolve over time, initially high [Na] and [K], evolving to a Ca-rich fluid, and finally returning to the groundwater composition. This evolving chemistry will affect the long-term performance of the repository, altering the physical and chemical properties, including radionuclide behaviour. Understanding these changes forms the basis for predicting the long-term evolution of the repository. This study focused on the determination of the nature and extent of the chemical reaction, as well as the formation and persistence of secondary mineral phases within a mudstone, comparing data from sequential flow experiments with the results of reactive transport modelling. The reaction of the mudstone with the cement leachates resulted in small changes in pH with the precipitation of calcium aluminium silicate hydrate (C-(A-)S-H) phases of varying compositions. As the system evolves, secondary C-(A-)S-H phases re-dissolve and are replaced by secondary carbonates. This general sequence was successfully simulated using reactive transport modelling.

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