Effects of the Orientation of Clay Particles and Ionic Strength on Diffusion and Activation Enthalpies of I− and Cs+ Ions in Compacted Bentonite (II)

2006 ◽  
Vol 932 ◽  
Author(s):  
Haruo Sato
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Free Water ◽  
Dry Density ◽  
Combined Effects ◽  
Clay Particles ◽  
Compacted Bentonite ◽  
Parallel Direction ◽  
Ionic Diffusivity ◽  
Cs Ions

ABSTRACTThe apparent diffusivities (Da) and activation enthalpies (ΔEa) for I− and Cs+ ions in compacted Na-smectite were obtained in the parallel and perpendicular directions to the orientation of smectite particles as a function of smectite's dry density (0.9-1.4 Mg/m3), salinity ([NaCl]=0.01, 0.51 M) and temperature (295-333 K). The Da-values for both ions tended to be higher in the parallel direction than in the perpendicular direction to the orientation of smectite particles. The Da-values of I− ions in the parallel direction decreased with increasing salinity only at low dry density, but those of Cs+ ions increased with increasing salinity for all conditions. Based on this, it is interpreted that I− ions predominantly diffuse in external pores and Cs+ ions diffuse in both interlayer and external pores. The ΔEa-values forI− ions are at similar levels as those for the ionic diffusivity in free water (D°) of I− ions at low dry density and increased with increasing dry density. The ΔEa-values for Cs+ ions are higher than those for the D° of Cs+ ions even at low dry density and increased with increasing dry density. Such high ΔEa-values for Cs+ ions are considered to be due to the combined effects of the ion exchange enthalpy between Cs+ and Na+ ions in smectite and the lowering in the activity of porewater.

Effects of the Orientation of Clay Particles and Ionic Strength on Diffusion and Activation Enthalpies of I−and Cs+ Ions in Compacted Bentonite

2004 ◽  
Vol 824 ◽  
Author(s):  
Haruo Sato
Keyword(s):  
Ionic Strength ◽  
Free Water ◽  
Interlayer Distance ◽  
Perpendicular Direction ◽  
Dry Density ◽  
Clay Particles ◽  
Compacted Bentonite ◽  
Parallel Direction ◽  
Cs Ions ◽  
And Diffusion

AbstractApparent diffusivities (Da) for I− and Cs+ in compacted Na-smectite were studied as a function of smectite's dry density (0.9–1.4 Mg/m3, ionic strength (IS: [NaCl]=0.01, 0.51 M), temperature (22–60 °C) and diffusion directionto the orientated direction of smectite particles. The Da-values for both ions in parallel direction to the orientated direction showed a tendency to be higher than those in the perpendicular direction at lowIS. The Da-values for I− showed different trends depending on diffusion direction and dry density at high IS, but Da-values for Cs+ increased with increasing IS in both diffusion directions. The activation enthalpies (ΔEa) for I−, slightly higher than that of diffusivity in free water (Do) at low IS, similar level to that of Do at high IS, increased with increasing dry density. While, ΔEa-values for Cs+, clearly higher than that of Do for all conditions, increased with increasing dry density. Since it is known that interlayer distance depends on both dry density and IS, diffusive pathway is considered to differ depending on the charge of diffusion species.

Diffusion Behavior of Humic Acid in Compacted Bentonite: Effect of Ionic Strength, Dry Density and Molecular Weight of Humic Acid

2008 ◽  
Author(s):  
Kazuki Iijima ◽  
Seiichi Kurosawa ◽  
Minoru Tobita ◽  
Satoshi Kibe ◽  
Yuji Ohuchi
Keyword(s):  
Molecular Weight ◽  
Humic Acid ◽  
Ionic Strength ◽  
Dry Density ◽  
Diffusion Behavior ◽  
Compacted Bentonite

Thermodynamic Properties of Water in Compacted Bentonite Under External Pressure-free Conditions

1994 ◽  
Vol 353 ◽  
Author(s):  
Yuji Torikai ◽  
Seichi Sato ◽  
Hiroshi Ohashi
Keyword(s):  
Thermodynamic Properties ◽  
Water Content ◽  
Pure Water ◽  
Bound Water ◽  
Free Water ◽  
External Pressure ◽  
Dry Density ◽  
X Ray Diffraction ◽  
Molar Gibbs Free Energy ◽  
Compacted Bentonite

AbstractIn an attempt to determine the thermodynamic properties of water in bentonite, the vapor pressure of water in compacted bentonite was measured as functions of water content and temperature, under external pressure-free conditions. The relative partial molar Gibbs free energy ΔGH2O, enthalpy ΔHH2Oand entropy ΔSH2O of tne waler in bentonite were determined at temperature of 298.15K. The interlayer distance of montmorillonite in bentonite was also measured by X-ray diffraction.It is probable that one fourth of the total water included in the bentonite at water content of 20.3wt% and dry density of 1.76 × 103kg/m3 is nearly free water; the water is not regarded as dilute electrolytic solution but the solution with higher ionic strength. Another one fourth of the water in the bentonite at the water content is bound water; the partial molar entropy of the bound water referred to pure water is from a half to whole of solidification entropy of pure water. The remainder is regarded as intermediately bound water.

Evolution of the Porewater Chemistry in Compacted Bentonite

1997 ◽  
Vol 506 ◽  
Author(s):  
Arto Muurinen ◽  
Jarmo Lehikoinen
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Room Temperature ◽  
External Solution ◽  
Exchangeable Cations ◽  
Anaerobic Conditions ◽  
Compacted Bentonite ◽  
Porewater Chemistry ◽  
Exchange Processes ◽  
Water Ratio

ABSTRACTThe evolution of porewater chemistry in bentonite was studied in solution-bentonite interaction experiments under anaerobic conditions at room temperature. The parameters varied were the bentonite density, bentonite-to-water ratio (b/w), ionic strength of the solution, and the composition of bentonite. At the end of the experiment, the equilibrating solution and the porewater squeezed out of the bentonite samples were analysed. This paper presents the preliminary experimental results of these ongoing studies. The evolution of porewater chemistry was determined by the dissolving components initially present in the bentonite together with the ions coming with water from the surroundings. Ion-exchange processes occured between the exchangeable cations of montmorillonite and the cations in the water. The obtained concentrations in the external solution and porewater strongly depended on the b/w used. The concentrations in the squeezed porewaters were clearly lower than in the external waters and decreased with increasing density during squeezing.

Diffusion and Migration of Ions in Sedimentary Rock Matrix: Effects of Ionic Strength and Tracer Concentration on Diffusion of Cs+ ions in Sandstone

2003 ◽  
Vol 807 ◽  
Author(s):  
Haruo Sato
Keyword(s):  
Ionic Strength ◽  
Matrix Effects ◽  
Chemical Properties ◽  
Effective Diffusivity ◽  
Concentration Profiles ◽  
Tracer Concentration ◽  
And Migration ◽  
Physical And Chemical ◽  
Cs Ions ◽  
And Chemical Properties

ABSTRACTIn-diffusion experiments for Cs+ and I− in sandstone were performed as a function of ionic strength ([NaCl]=0.01, 0.51M) and tracer concentration ([CsI]=7.5E-5, 1.5E-2M) together with the measurements of the physical and chemical properties of sandstone, and apparent diffusivities (Da) for Cs+ were obtained. The obtained Da-values for Cs+ scarcely depended on [NaCl], but increased with increasing [Cs+]. This trend is consistent with that of rock capacity factors (α), indicating that distribution coefficient (Kd) onto sandstone and effective diffusivity scarcely depend on [NaCl]. The concentration profiles of I− were all in already breakthrough. Although this indicates that I− diffusion is faster than that of Cs+, the concentration profiles of I− may have been lower than those for blank samples, judging synthetically from the correlations between α-values and the concentration profiles of Cs+ and from the concentration profiles of I− in the blank samples. Finally, the effects of [Cs+] and[NaCl] on Kd/-values for Cs+ were discussed from the viewpoint of adsorption by ion exchange and electrostatic attraction. The kd-values were considered to be combined sorption by both reactions.

Modification of the AMX membrane surface by polyethyleneimine: Effect of ionic strength on the membrane ion exchange selectivity

2016 ◽  
Vol 94 (12) ◽  
pp. 2386-2393 ◽  
Author(s):  
Islem Louati ◽  
Fatma Guesmi ◽  
Chiraz Hannachi ◽  
Béchir Hamrouni
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Membrane Surface ◽  
Exchange Selectivity

scholarly journals Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

SPE Journal ◽  
2017 ◽  
Vol 23 (01) ◽  
pp. 84-101 ◽  
Author(s):  
Maxim P. Yutkin ◽  
Himanshu Mishra ◽  
Tadeusz W. Patzek ◽  
John Lee ◽  
Clayton J. Radke
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Crude Oil ◽  
Surface Charge ◽  
Double Layer ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Diffuse Double Layer ◽  
Low Salinity ◽  
Low Salinity Waterflooding

Summary Low-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO2) and possibly supplemented with additional ionic species, such as sulfates or phosphates. When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO2 content of a carbonate reservoir, originating from CO2-rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation. A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcite-surface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes. Our evaluation of calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO2. In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved.

scholarly journals Boron Removal from Aqueous Solutions by Strong Base Anion-exchange Resin Batch and Column Experiments

2021 ◽  
Author(s):  
György Pátzay ◽  
József Dobor ◽  
Emil Csonka ◽  
Gábor Lozsi ◽  
Ferenc Feil
Keyword(s):  
Ion Exchange ◽  
Acid Solution ◽  
Boric Acid ◽  
Anion Exchange ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Free Water ◽  
Sulfate Solution ◽  
Boric Acid Solution ◽  
Strong Base

Borate ion exchange capacity of Purolite NRW600 strong base anion resin in hydroxide form and mixed bed NRW600+NRW100 ion exchange was investigated with static experiments. Anion exchange resin was saturated with 0.1–45 g/dm3 concentration boric acid solution in a static mixer at 20, 30, 40 and 50 °C at 150 rpm for 24 hours. Remaining borate content of saturation solutions was deter-mined with ion chromatography and ICP-OES. The amount of fixed borate as borate anions increased with the saturation borate concentration as well as in case of simple anion exchange as in case of mixed bed.Column sorption-elution study was carried out by using strong base anion exchange resins (Purolite NRW600 and Amberlite IRN78). Resins in hydroxide and in chloride forms were saturated in column with 5–40 g/dm3 boric acid solution in excess. The resin was then eluted with 200 cm3 salt free water with 5 cm3/min at 25 °C and then eluted by 1 mol/dm3 sodium-sulfate solution with 5 cm3/min. The effluent was collected and analyzed for borate content by titrimetric method. In chloride form the resin adsorbed and released much less borate. Effective borate and polyborate sorption needs hydroxide ions in resin phase.

Influence of Operational Conditions on Retardation Parameters Measured by Diffusion Experiment in Compacted Bentonite

2010 ◽  
Vol 1265 ◽  
Author(s):  
Ishii Yasuo ◽  
Yoshimi Seida ◽  
Yukio Tachi ◽  
Hideki Yoshikawa
Keyword(s):  
Mass Transfer ◽  
Ionic Strength ◽  
Test Solution ◽  
Test Method ◽  
Diffusion Experiment ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Operational Conditions ◽  
Diffusion Data ◽  
Compacted Bentonite

AbstractInfluence of operation factors in diffusion test of compacted bentonite (such as agitation of test solution in the reservoir, feed rate of the test solution and mass transfer resistance in the filter) on the diffusion data was examined by reservoir depletion (RD) test method using Cs+. The influence of these factors on the diffusion data was also analyzed based on the mathematical sorption-diffusion model which considered the feed of test solution and mass transfer resistance in the filter as well. The reservoir depletion data showed some remarkable influences of these operational conditions, especially in the system with low ionic strength. Change in mass transfer resistance at filter-compacted bentonite due to the operational conditions was found to be potential factor which disturb the diffusion data. The influence was reduced in the system with high ionic strength of solution.

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