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Iodine radioisotopes released during nuclear fuel reprocessing must be removed from the off-gas stream before discharge. One promising material for iodine capture is reduced silver mordenite (Ag0Z). Nevertheless, the adsorbent's capacity will degrade, or age, over time when the material is exposed to other off-gas constituents. Though the overall impact of aging is known, the underlying physical and chemical processes are not. To examine these processes, Ag0Z samples were prepared and aged in 2% NO2 in dry air and in 1% NO in N2 gas streams at 150 °C for up to six months. Aged samples were then characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray absorption spectroscopy. These techniques show that aging involves two overarching processes: (i) oxidation of the silver nanoparticles present in Ag0Z and (ii) migration of oxidized silver into the mordenite's inner network. Silver on the nanoparticle's surface is oxidized through adsorption of O2, NO, and NO2. Raman spectroscopy and X-ray absorption spectroscopy indicate that nitrates are the primary products of this adsorption. Most of these nitrates migrate into the interior of the mordenite and exchange at framework binding sites, returning silver to its unreduced state (AgZ). The remaining nitrates exist at a persistent concentration without aggregating into bulk-phase AgNO3. X-ray absorption spectroscopy results further indicate that iodine adsorption occurs on not just Ag0Z but also on AgZ and a portion of the nitrates in the system. AgZ adsorbs a sizable quantity of iodine early in the aging process, but its capacity drops rapidly over time. For well-aged samples, nitrates are responsible for up to 95% of mordenite's iodine capacity. These results have enhanced our understanding of the aging process in silver mordenite and are expected to guide the development of superior adsorbents for the capture of radioactive iodine from reprocessing off-gas.

With global demand for nuclear power expected to rise, new nuclear fuel resources must be explored to ensure the viability and sustainability of nuclear power. Uranium recovery from seawater is one potential source, though the low concentration of uranium in seawater is a significant obstacle. As a concentrate of seawater, desalination brine reject would have a significantly higher uranyl concentration. In this work, the adsorption of uranium and competing ions in brine reject is investigated. Adsorption experiments were performed over 84 days in 5-gallon batch tanks with amidoxime adsorbents and samples taken from the feed seawater and reverse osmosis brine reject of the Tampa Bay Desalination Plant. The aqueous concentration and adsorbed mass of uranium, zinc, copper, iron, vanadium, calcium, and magnesium were determined through inductively coupled plasma mass spectroscopy. Aqueous adsorption modeling was used to simulate speciation and adsorption of these ions under the experimental conditions. The ad...

This study focuses on the influence of hydrophilic groups and metal-ion loading on adsorbent polymer conformation, which controls access to adsorption sites and may limit adsorption capacity. Gaining a better understanding of the factors that influence conformation may yield higher-capacity adsorbents. Polyamidoxime (PAO), deuterated-PAO polyacrylic acid diblock copolymers (d-PAO-b-PAA), and randomly configured copolymers (PAO-co-PAA) were synthesized and characterized by neutron reflectometry in air and D2O. For d-PAO-b-PAA, characterization was also performed after alkali conditioning and in simulated seawater. PAO and PAO-co-PAA, with similar molecular weight and grafting density, extended from 95-A thickness in air to 180 and 280-A in D2O, respectively. This result suggests that polymer swelling may cause the additional adsorption capacity observed when polymer hydrophilicity increases. Two d-PAO-b-PAA samples, A and B, with a d-PAO thickness of 55-A swelled to 110-A and 140-A, respectively, with an overall thickness increase of ∼160% in D2O. After alkali conditioning, molecular interactions increased the density of PAA near the PAO-PAA interface, while the d-PAO thickness only decreased by ∼10 A. The d-PAO thickness of both samples declined to ∼90-A after adsorption in simulated seawater due to polymer-chain crosslinking. These results are expected to aid in improving adsorbent synthesis to increase uranium capacity.

Adsorption is a complex physicochemical process involving interparticle transport, interphase mass-transfer, intraparticle diffusion, and surface reactions. Although the exact description of the adsorption process will inevitably vary from system to system, it will always be governed by those primary mechanisms. Therefore, by devising a model framework that can inherently include those mechanisms, it would be possible to create a modeling platform on which many different adsorption problems could be solved numerically. To accomplish this task, a generalized 1-D conservation law model was created to include the necessary mechanisms of adsorption on several different geometrical domains. Specific model applications for adsorption were developed under that framework and validated using experimental data available in literature or obtained in this work. This modeling platform makes it easier to model various adsorption problems and develop new adsorption models because of the common treatment of the mathematics governing the physical processes. © 2017 American Institute of Chemical Engineers AIChE J, 2017

This work is related to the removal of tritiated water and radioactive iodine from off-gases released during spent nuclear fuel reprocessing. Specifically, it is focused on the adsorption equilibrium of water on reduced silver mordenite (Ag0Z), which is the state-of-art solid adsorbent for iodine retention in the off-gas treatment. As the off-gases contain different gas species, including iodine and water, Ag0Z would take up iodine and water simultaneously during the adsorption process. Therefore, understanding the adsorption of water on Ag0Z is important and necessary for studying the performance of Ag0Z in off-gas treatment processes. The isotherms of water (nonradioactive water) on Ag0Z were obtained at temperatures of 25, 40, 60, 100, 150, and 200 °C with a continuous-flow adsorption system. The data were analyzed using the Heterogeneous Langmuir and generalized statistical thermodynamic adsorption (GSTA) models, and thermodynamic parameters of the isotherms were obtained from both models. Both models...

Seawater contains uranium at an average concentration of 3.3 ppb, as well as a variety of other ions at either overwhelmingly higher or similar concentrations, which complicate the recovery of uranium. This report describes an investigation of the effects of various factors such as uranium speciation and presence of salts including sodium, calcium, magnesium, and bicarbonate, as well as trace elements such as vanadium on uranium adsorption kinetics in laboratory experiments. Adsorption models are also developed to describe the experimental data of uranium extraction from seawater. Results show that the presence of calcium and magnesium significantly slows down the uranium adsorption kinetics. Vanadium can replace uranium from amidoxime-based adsorbent in the presence of sodium in the solution. Results also show that bicarbonate in the solution strongly competes with amidoxime for binding uranium, and thus slows down the uranium adsorption kinetics. Developed on the basis of the experimental findings, the ...

The influence of electrostatic charge on the adhesive force between spherical particles and planar surfaces in atmospheric systems was studied using atomic force microscopy. Electrical bias was applied to modify the surface charge, and it was found that application of a stronger positive bias to a particle induces a stronger total adhesive force. The sensitivity of the system to changes in the bias depended on the surface charge density. For larger-size particles, the contribution of the electrostatic force decreased, and the capillary force became the major contributor to the total adhesive force. The influence of water adsorption on the total adhesive force and, specifically, on the contribution of the electrostatic force depended on the hydrophobicity of interacting surfaces. For a hydrophilic surface, water adsorption either attenuated the surface charge or screened the effect of surface potential. An excessive amount of adsorbed water provided a path to surface charge leakage, which might cancel out the electrostatic force, leading to a reduction in the adhesive force. Theoretically calculated forces were comparable with measured adhesive forces except for mica which has a highly localized surface potential. The results of this study provide information on the behavior of charged colloidal particles in atmospheric systems.

This work is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ∼4:6. Our results showed that the GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it w...

Prediction of multicomponent adsorption equilibria has been investigated for several decades. While there are theories available to predict the adsorption behavior of ideal mixtures, there are few purely predictive theories to account for nonidealities in real systems. Most models available for dealing with nonidealities contain interaction parameters that must be obtained through correlation with binary-mixture data. However, as the number of components in a system grows, the number of parameters needed to be obtained increases exponentially. Here, a generalized procedure is proposed, as an extension of the predictive real adsorbed solution theory, for determining the parameters of any activity model, for any number of components, without correlation. This procedure is then combined with the adsorbed solution theory to predict the adsorption behavior of mixtures. As this method can be applied to any isotherm model and any activity model, it is referred to as the generalized predictive adsorbed solution theory. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2600–2610, 2015

Recovering uranium from seawater has been the subject of many studies for decades, and has recently seen significant progress in materials development since the U.S. Department of Energy (DOE) has become involved. With DOE direction, the uranium uptake for amidoxime-based polymer adsorbents has more than tripled in capacity. In an effort to better understand how these new adsorbent materials behave under different environmental stimuli, several experimental and modeling based studies have been employed to investigate impacts of competing ions, salinity, pH, and other factors on uranium uptake. For this study, the effect of temperature and type of comonomer on uranium adsorption by three different amidoxime adsorbents (AF1, 38H, AI8) was examined. Experimental measurements of uranium uptake were taken in 1-L batch reactors from 10 to 40 °C. A chemisorption model was developed and applied in order to estimate unknown system parameters through optimization. Experimental results demonstrated that the overall uranium chemisorption process for all three materials is endothermic, which was also mirrored in the model results. Model simulations show very good agreement with the data and were able to predict the temperature effect on uranium adsorption as experimental conditions changed. This model may be used for predicting uranium uptake by other amidoxime materials.

Off-gases produced during the reprocessing of used nuclear fuel (UNF) include 129I2, 3HHO, 14CO2, 85Kr, and 135Xe, which are volatilized out into the off-gas. In order to meet regulatory requirements for reprocessing plant emissions, these gases must be captured and removed from the off-gas stream prior to off-gas emission. Of particular interest are the noble gases, Kr and Xe, which can be fairly difficult to remove from the off-gas due to their low chemical reactivity. Thus, this work is focused on utilizing engineered adsorbents, AgZ-PAN and HZ-PAN, to capture Kr and Xe from a mixed-gas stream at relatively low temperatures (191–295 K) and various flow rates (50–2000 mL/min). Isothermal data for Kr and Xe on each adsorbent are analyzed to produce the Langmuir parameters needed to model the mixture adsorption capacities at relevant temperatures using the Extended Langmuir model. Those parameters are then incorporated into a fixed-bed adsorption model developed in this work using the Mulitphysics Object-Oriented Simulation Environment (MOOSE). That model is used to simulate breakthrough times for Kr and Xe in packed columns of AgZ-PAN and HZ-PAN, ranging in length from 6 to 20 in., at relevant temperatures and flow rates. Breakthrough times varied from nearly instantaneous for Kr in AgZ-PAN to 30 h for Xe in HZ-PAN. After the developed model was validated by comparisons with experimental breakthrough data, the model framework was used to simulate the performance of multiple fixed-bed columns connected in series.

Based on the electrosorption of ions by charged electrodes, the capacitive deionization method was considered for ion removal from saline water using mesoporous carbon electrodes. Mesoporous carbon was synthesized via a self-assembly method, with a narrow pore size distribution in the range of 6–10 nm. It was found that the rates of ion sorption and release by mesoporous carbon electrodes increase with an increase in the temperature of the solution. A drift in the conductivity was observed during electrosorption of Instant Ocean solutions, which may be explained as the result of competition between ions of different valence and size. The diffusion coefficient of ions during electrosorption was evaluated as a function of temperature, and a transport model coupled with an electrical-double-layer model was employed to calculate the mass of salt adsorbed by the electrodes. The calculated cumulative mass of salt captured in the electrical double layers of the electrodes was compared to the experimental data at different temperatures.

The kinetic friction force and the adhesion force of Bacillus thuringiensis spores on planar surfaces in atmospheric systems were studied using atomic force microscopy. The influence of relative humidity (RH) on these forces varied for different surface properties including hydrophobicity, roughness, and surface charge. The friction force of the spore was greater on a rougher surface than on mica, which is atomically flat. As RH increases, the friction force of the spores decreases on mica whereas it increases on rough surfaces. The influence of RH on the interaction forces between hydrophobic surfaces is not as strong as for hydrophilic surfaces. The friction force of the spore is linear to the sum of the adhesion force and normal load on the hydrophobic surface. The poorly defined surface structure of the spore and the adsorption of contaminants from the surrounding atmosphere are believed to cause a discrepancy between the calculated and measured adhesion forces.

The project has made progress toward developing a comprehensive modeling capability for the capture of target species in off gas evolved during the reprocessing of nuclear fuel. The effort has integrated experimentation, model development, and computer code development for adsorption and absorption processes. For adsorption, a modeling library has been initiated to include (a) equilibrium models for uptake of off-gas components by adsorbents, (b) mass transfer models to describe mass transfer to a particle, diffusion through the pores of the particle and adsorption on the active sites of the particle, and (c) interconnection of these models to fixed bed adsorption modeling which includes advection through the bed. For single-component equilibria, a Generalized Statistical Thermodynamic Adsorption (GSTA) code was developed to represent experimental data from a broad range of isotherm types; this is equivalent to a Langmuir isotherm in the two-parameter case, and was demonstrated for Kr on INL-engineered sorbent HZ PAN, water sorption on molecular sieve A sorbent material (MS3A), and Kr and Xe capture on metal-organic framework (MOF) materials. The GSTA isotherm was extended to multicomponent systems through application of a modified spreading pressure surface activity model and generalized predictive adsorbed solution theory; the result is the capability tomore » estimate multicomponent adsorption equilibria from single-component isotherms. This advance, which enhances the capability to simulate systems related to off-gas treatment, has been demonstrated for a range of real-gas systems in the literature and is ready for testing with data currently being collected for multicomponent systems of interest, including iodine and water on MS3A. A diffusion kinetic model for sorbent pellets involving pore and surface diffusion as well as external mass transfer has been established, and a methodology was developed for determining unknown diffusivity parameters from transient uptake data. Two parallel approaches have been explored for integrating the kernels described above into a mass-transport model for adsorption in fixed beds. In one, the GSTA isotherm kernel has been incorporated into the MOOSE framework; in the other approach, a focused finite-difference framework and PDE kernels have been developed. Issues, including oscillatory behavior in MOOSE solutions to advection-diffusion problems, and opportunities have been identified for each approach, and a path forward has been identified toward developing a stronger modeling platform. Experimental systems were established for collection of microscopic kinetics and equilibria data for single and multicomponent uptake of gaseous species on solid sorbents. The systems, which can operate at ambient temperature to 250°C and dew points from -69 to 17°C, are useful for collecting data needed for modeling performance of sorbents of interest. Experiments were conducted to determine applicable models and parameters for isotherms and mass transfer for water and/or iodine adsorption on MS3A. Validation experiments were also conducted for water adsorption on fixed beds of MS3A. For absorption, work involved modeling with supportive experimentation. A dynamic model was developed to simulate CO2 absorption with chemical reaction using high alkaline content water solutions. A computer code was developed to implement the model based upon transient mass and energy balances. Experiments were conducted in a laboratory-scale column to determine model parameters. The influence of geometric parameters and operating variables on CO2 absorption was studied over a wide range of conditions. This project has resulted in 7 publications, with 3 manuscripts in preparation. Also, 15 presentations were given at national meetings of ANS and AIChE and at Material Recovery and Waste Forms Campaign Working Group meetings.« less

The fundamental mechanism of electrosorption of ions developing a double layer inside nanopores was studied via a combination of experimental and theoretical studies. A novel graphitized-carbon monolithic material has proven to be a good electrical double-layer capacitor that can be applied in the separation of ions from aqueous solutions. An extended electrical double-layer model indicated that the pore size distribution plays a key role in determining the double-layer capacitance in an electrosorption process. Because of the occurrence of double-layer overlapping in narrow pores, mesopores and micropores make significantly different contributions to the double-layer capacitance. Mesopores show good electrochemical accessibility. Micropores present a slow mass transfer of ions and a considerable loss of double-layer capacitance, associated with a shallow potential distribution inside pores. The formation of the diffuse layer inside the micropores determines the magnitude of the double-layer capacitance at low electrolyte concentrations and at conditions close to the point of zero charge of the material. The effect of the double-layer overlapping on the electrosorption capacitance can be reduced by increasing the pore size, electrolyte concentration, and applied potential. The results are relevant to water deionization.

This study investigates the effect of surfactants and key design parameters on the removal efficiency (RE) of paramagnetic colloidal particles by high-gradient magnetic filtration, and attempts to predict the effect of these parameters by a trajectory model. Magnetic filtration offers an advantage over conventional filtration in that it can achieve a reversible and selective separation. An aqueous suspension of paramagnetic colloidal ferric oxide (Fe 2 O 3 ) particles was treated with sodium dodecyl sulfate (SDS) and delivered through a column containing a stainless steel wool filter matrix, which was mounted between the poles of an electromagnet. The RE of the surfactant-treated particles was measured by analyzing effluent samples for Fe 2 O 3 concentration. The effect of the applied magnetic induction, fluid velocity, and radius of the stainless steel wires on the RE was tested and compared for both surfactant-treated and untreated particles. These three factors had a marked effect on the RE of surfactant-treated particles. An increase in applied magnetic induction from 0.2 to 0.5 T increased the RE from 79.9 to 93.4%, a decrease in wire radius from 49 to 15 μm increased the RE from 60.2 to 93.4%, and a decrease in fluid velocity from 0.5 to 0.1 cm/s increased the RE from 69.5 to 95.3%. In the absence of a magnetic field (0 T), the RE was 10.8%. The predictions of the trajectory model agreed closely with these results. The same factors had a negligible effect on the RE of untreated particles. Over the range of all three parameters, the RE varied from 90 to 99%, but these variations were not statistically significant. In the absence of applied magnetic induction, the RE was 90.1%. These results differed markedly from the trajectory model predictions and demonstrated that nonmagnetic filtration mechanisms are primarily responsible for the capture of particles without SDS. Regeneration experiments indicated that the particles were captured in the primary minimum of the potential energy. On the other hand, these results showed that the magnetic filtration mechanism is primarily responsible for the removal of particles treated with SDS and that these particles are captured in the secondary minimum of the potential energy. Therefore, surfactant adsorption onto colloidal particles can potentially preserve and enhance the advantages of magnetic filtration (e.g., reversibility and selectivity).

This study is focused on the formation of the electrical double layer (EDL) inside uniform platinum nanochannels. Strong hysteresis of adsorption/desorption of protons observed in cyclic voltammetry experiments suggests that adsorption is controlled by ion diffusion through the charged nanochannels whereas desorption is controlled by the electrical potential. It was determined that the nanostructured platinum electrodes prepared in this study were selective for halogen ions. The sorption capacity decreased in the order of F- > Cl- > Br-.

Electrosorption is generally defined as potential-induced adsorption on the surface of charged electrodes. After polarization of the electrodes, ions are removed from the electrolyte solution by the imposed electric field and adsorbed onto the surface of the electrodes. Experimental and modeling studies were conducted using two types of carbon aerogel composites of different surface areas to provide a better understanding on the mechanisms of electrosorption. The experimental results revealed that no significant specific adsorption of F− ions occurred, while strong specific adsorption was observed for NO3− and Cu2+ ions. In addition, although the two types of carbon aerogel electrodes had different surface areas, their capacities were found to be very similar because of the electrical double-layer overlapping effect in micropores. An electrical double-layer model developed in our previous work (16), in which the electrical double-layer overlapping correction is included, is expanded in the present work by considering the effect of the specific adsorption on the electrosorption process. Modeling results were compared with experimental data obtained under various conditions. When the overlapping effect and specific adsorption were considered, the model provided results that were in good agreement with experimental data.

An electrical double-layer model is developed to predict electrosorption of ions from aqueous solutions by carbon aerogel electrodes. The carbon aerogel electrodes are treated as electrical double-layer capacitors, and electrosorption is modeled using classical electrical double-layer theory. Because of the porous characteristics of the electrodes, the total capacity of the system is obtained by summing the contributions of the individual pores. The pore size distribution of the carbon aerogel is measured by the physical adsorption of N2 and CO2 as well as by mercury intrusion porosimetry. When a pore has a width smaller than a specific value (cutoff pore width), it does not contribute to the total capacity because of the electrical double-layer overlapping effect. This effect greatly reduces the electrosorption capacity for electrodes with significant numbers of micropores, such as carbon aerogel; thus, it is considered in the electrical double-layer model. The model in this study focuses on the electros...

Copper adsorption by granular activated carbon is reported in this paper. The experimental section includes titrations of activated carbon, as well as equilibrium and kinetic studies of copper adsorption. The potentiometric titration results show that the point of zero charge is 9.5, and that the surface charge increases with decreasing pH. The adsorption of copper strongly depends on solution pH and increases from 10 to 95% at pH ranging from 2.3 to 8. A dramatic increase in pH and emission of small gas bubbles are observed during the experiments, which may result from adsorption of hydrogen ion and/or reduction-oxidation reactions. The two-pK triple-layer model is employed to describe copper adsorption. KINEQL, an adsorption kinetics algorithm, is used to represent the experimental data, and it is found that the model can describe reasonably well the experimental measurements of surface charge, adsorption equilibrium, and adsorption kinetics. Calculations show that formation of the surface-metal complexes SO−Cu2+ and SO−CuOH+ (a hydrolysis product of SO−Cu 2+) in the outer layer around the surface of carbon results in removal of copper ion. It is also found that mass transfer controls the adsorption rate, and that adsorption occurs in the micropore region where both external mass transfer and diffusion are important.

A new diffusion model is proposed to describe the uptake of organic solutes from aqueous solutions by soil. The model considers that the uptake process is controlled by the pore diffusion of solutes within the soil pellets, the adsorption of solutes by the mineral fraction of soil, the surface diffusion of solutes along the mineral fraction surfaces, the partition of solutes into the soil organic matter, and the diffusion of solutes within the soil organic matter. An expression, in the Laplace domain, of the solute uptake by a soil pellet is obtained and with appropriate macroscopic conservation equations and standard numerical Laplace transform inversion techniques can be used to describe sorption and desorption as well as transport and distribution of organic solutes under a variety of conditions. On the basis of the uptake expression, a number of calculations are carried out with the objective to identify under which conditions the effect of diffusion into the soil organic matter, as well as the effects of dispersion and mineral adsorption, becomes important. Some comparisons of model predictions with experimental results are also provided to demonstrate the application of the model.

The second part of KINEQL, which calculates adsorption rates under the condition that adsorption is controlled by mass transfer, is described in this article. The adsorption process is analyzed again in terms of three separate but interacting phenomena: surface ionization, complex formation, and the presence of an electrostatic double layer adjacent to adsorbent surfaces. A general form of a rate expression, suitable for transport-controlled cases, is formulated; this rate expression represents an approximate form of the intraparticle equation that has been found by other investigators to be very accurate for batch processes. Sample calculations demonstrating the use of the algorithm to calculate adsorption histories of cadmium on aluminum oxide are presented. Matching of experimental results with model calculations is obtained only after a combined macropore and micropore diffusion model is employed. In this model, macrodiffusion and microdiffusion act in parallel and independently. Reasonable values of the transport parameters are obtained in the case where only the simple metal ion diffuses into the interior of the adsorbents.

This chapter covers applications of the model and algorithm developed in the two previous chapters to calculate the kinetics of metal ion adsorption from aqueous solutions. A number of specific problems are presented. Model predictions are also compared with experimental results available in the literature.

In this book, kinetic uptake models of metal ions from aqueous solutions by adsorbents in various systems were presented and applied. Specifically, the uptake of metal ions from aqueous solutions by adsorbents such as hydrous oxides and activated carbon was analyzed.

The development of a comprehensive description of metal ion adsorption from aqueous solutions at equilibrium and non-equilibrium conditions, based on the principles of surface complexation models, is presented. This presentation begins with the various surface complexation models, previously developed to describe adsorption equilibrium, and then further develops the models for the prediction of adsorption rates.

Several models formulated by past researchers to describe the adsorption of ionic solutes at solid-solution interfaces are presented. Also included is the development of a model that establishes a relationship between the surface charge density and the surface electrical potential, inside the porous structure of an adsorbent.

The development of a general algorithm for the calculation of metal ion adsorption from aqueous solutions at equilibrium and non-equilibrium conditions is presented. This algorithm, named KINEQL (Yiacoumi, 1992), incorporates elements from existing equilibrium algorithms with new elements for kinetic calculations.

Grand canonical Monte Carlo (GCMC) simulations are employed to study the selective electrosorption of ions from a mixture of symmetric and asymmetric electrolytes confined in pores and results are compared to experimental observations obtained via cyclic voltammetry and batch electrosorption equilibrium experiments. GCMC simulations have the advantage over other Monte Carlo methods to unambiguously quantify the total number of ions in the pore solution. The exclusion parameter and selectivity factor are used to evaluate the selective capacity of pores toward different ionic species under various conditions. The number of coions inside the pore solution is determined by the proportion of different counterions present in the double-layer region. Because of the competitive effects resulting from asymmetries in charge and size associated with different ions, the electrosorption selectivity of small monovalent over large divalent counterions first decreases with increasing surface charge, passes through a minimum, and then increases with further increase in surface charge. At low and moderate surface charge densities, the fact that large divalent counterions preferentially screen the surface charge has a strong effect on pore occupancy; whereas at a very high surface charge density, size-exclusion effects dominate and determine the accessibility of different ions into the pores. Therefore, electrosorption selectivity of ions from a mixture of electrolytes could, in principle, be achieved via tuning the electrical double-layer formation inside the pores through the regulation of surface charge tailored for different ion characteristics. The findings of this work provide important information relevant to ion selectivity during separation processes and energy storage in supercapacitors.