Dissolution Rate Of CO2 Research Articles

Enhancing carbon mineralization of slag leachate using amine-functionalized magnetic nanoparticle clusters

Carbon mineralization—converting carbon dioxide (CO2) into stable carbonate minerals, such as calcium carbonate (CaCO3)—has attracted much attention as a permanent way to sequester CO2. In this study, we developed a novel method for improving the efficiency of carbon mineralization using amine-functionalized magnetic nanoparticle clusters (A-MNCs). To prepare them, magnetic nanoparticle clusters composed of tens of small Fe3O4 nanoparticles were treated with 3-aminopropyltriethoxysilane to functionalize amine groups on their surfaces. When CO2 was bubbled into a NaOH solution, the rate of CO2 dissolution was enhanced in the presence of A-MNCs, mostly due to physical effects such as grazing and hydrodynamic effects that improved mass transfer between the solution and CO2 bubbles. In addition, A-MNCs promoted carbon mineralization in a NaOH solution containing Ca2+ by providing an additional mineralization route via carbamate formation, resulting in a threefold increase in efficiency to 81 %. We demonstrated that A-MNCs could be applied to leachate from slag, a byproduct of commercial steelmaking, increasing the efficiency by 2.6 times compared to the absence of A-MNCs. The resulting CaCO3 precipitate was confirmed to be calcite using X-ray diffraction and scanning electron microscopy. Furthermore, after the mineralization, A-MNCs were easily separated from the solution using a permanent magnet, while retaining their performance.

INVESTIGATION OF CARBON DIOXIDE ABSORPTION CAPACITY AND DISSOLUTION RATE WITH AMINO ACID SALT SOLUTIONS: SODIUM AND POTASSIUM GLYCINATE

Global warming is a major world problem and causes climate change. The primary cause of global warming is carbon dioxide (CO2) emissions. Ongoing studies are being conducted to mitigate the effects of this problem. Anthropogenic CO2 emissions occur by burning fossil fuels to generate power and heat. To combat this problem, CO2 must be captured from point emission sources or directly from air. The conventional method to remove CO2 at the point emission sources is post-combustion systems. In these systems, absorption process is generally used to diminish CO2 emission and capturing at the source. Current researches aim to find an efficient and alternative solution to absorption. In this work, sodium glycinate (NaGly) and potassium glycinate (KGly), which are amino acid salt solutions, were investigated for CO2 absorption. Amino acid salt solutions have shown similar absorption kinetics and capacities to amine-based solutions due to same functional group. These solutions are usually more stable to oxidative degradation and have low volatilities, higher surface tensions and the viscosities are very close to waters. Experiments were performed using a stirred cell system at ambient temperature (20°C) and atmospheric pressure (91 kPa), in Ankara, Türkiye. In experiments, sodium glycinate and potassium glycinate concentration was ranged between 0.1 and 1.5 M. The experiments were also repeated with sodium hydroxide and potassium hydroxide in the same concentration range for comparison. In addition, the amino acid salt solutions examined in this study were compared with alkaline solutions and glycine in terms of total CO2 absorption capacity and CO2 dissolution rate. As a result of the experiments, the potassium glycinate solutions gave approximately 1.4 times better results than the sodium glycinate solutions at the highest concentration. Also, functional groups were determined by FTIR analysis of pure and CO2-loaded potassium glycinate solution.

Density-Driven CO2 Dissolution in Depleted Gas Reservoirs with Bottom Aquifers

Depleted gas reservoirs with bottom water show significant potential for long-term CO2 storage. The residual gas influences mass-transfer dynamics, further affecting CO2 dissolution and convection in porous media. In this study, we conducted a series of numerical simulations to explore how residual-gas mixtures impact CO2 dissolution trapping. Moreover, we analyzed the CO2 dissolution rate at various stages and delineated the initiation and decline of convection in relation to gas composition, thereby quantifying the influence of residual-gas mixtures. The findings elucidate that the temporal evolution of the Sherwood number observed in the synthetic model incorporating CTZ closely parallels that of the single-phase model, but the order of magnitude is markedly higher. The introduction of CTZ serves to augment gravity-induced convection and expedites the dissolution of CO2, whereas the presence of residual-gas mixtures exerts a deleterious impact on mass transfer. The escalation of residual gas content concomitantly diminishes the partial pressure and solubility of CO2. Consequently, there is an alleviation of the concentration and density differentials between saturated water and fresh water, resulting in the attenuation of the driving force governing CO2 diffusion and convection. This leads to a substantial reduction in the rate of CO2 dissolution, primarily governed by gravity-induced fingering, thereby manifesting as a delay in the onset and decay time of convection, accompanied by a pronounced decrement in the maximum Sherwood number. In the field-scale simulation, the injected CO2 improves the reservoir pressure, further pushing more gas to the producers. However, due to the presence of CH4 in the post-injection process, the capacity for CO2 dissolution is reduced.

Effect of Various Acid Solutions on the CO2 Dissolution Rate, Morphology, and Particle Size of Precipitated Calcium Carbonate Synthesized Using Seashells.

In this study, the influence of acid solutions on the production of precipitated calcium carbonate (PCC) using seashells was investigated. In terms of the Ca dissolution efficiency and atmosphere for dissolving CO32-, the results indicate that HCl, HNO3, CH3COOH, and HCOOH at 1.0 M were the most ideal among the acid solutions. The use of weak acids resulted in the low degree of dissolution of Al and Fe. These impurities could be mostly removed through the pH adjustment process, leading to PCC with a purity of 99% or more. Further, CH3COOH and HCOOH exhibited low CaCO3 carbonation efficiency owing to the hydrogen bonding of the carboxyl group and its hindering effect on the growth of CaCO3 particles. In addition, in the presence of the carboxyl group, the morphology tended to be oval, and the particle size was small. Particularly, when CH3COOH was used, the combined effect of the low initial Ca ion concentration and slow CO2 dissolution rate resulted in minimal changes during the carbonation time and the smallest particle size. However, variations in the degree of Ca concentration with a change in the acid solution concentration influenced the dominance of nucleation and particle growth, leading to variations in the particle size. The results of this study revealed that when manufacturing PCC using seashells, the appropriate acid solution must be selected to obtain the required PCC properties.

Impacts of Permeability Heterogeneity and Background Flow on Supercritical CO2 Dissolution in the Deep Subsurface

AbstractMotivated by CO2 capture and sequestration (CCS) design considerations, we consider the coupled effects of permeability heterogeneity and background flow on the dissolution of a supercritical CO2 lens into an underlying deep, confined aquifer. We present the results of a large‐scale Monte Carlo simulation study examining the interaction of background flow rate and three parameters describing multi‐Gaussian log‐permeability fields: mean, variance, and correlation length. Hundreds of high‐resolution simulations were performed using the PFLOTRAN finite volume software to model CO2 dissolution in a kilometer‐scale aquifer over 1,000 years. Predictive dimensionless scaling relationships relating CO2 dissolution rate to heterogeneity statistics, Rayleigh (Ra) and Péclet (Pe) numbers were developed for both gravitationally dominated free convection to background flow‐dominated forced convection regimes. An empirical criterion, Pe = Ra3/4, was discovered for regime transition. All simulations converged quickly to a quasi‐steady, approximately linear dissolution rate. However, this rate displayed profound variability between permeability field realizations sharing the same heterogeneity statistics, even under mild permeability heterogeneity. In general, increased heterogeneity was associated with a lower mean and higher variance of dissolution rate, undesirable from a CCS design perspective. The relationship between dissolution rate and background flow was found to be complex and nonlinear. Dimensionless scaling relationships were uncovered for a number of special cases. Results call into question the validity of the Boussinesq approximation in the context of modest‐to‐high background flow rates and the general applicability of numerical simulations without background flow.

Implications of CO[formula omitted] mass transport dynamics for large-scale CCS in basalt formations

Flood basalts have the potential for relatively rapid mineral trapping when used as an injection target for CO2 storage. Although CO2 mineral trapping in basalt has been studied in various ways, including two successful small-scale pilot projects, questions remain about how the system will behave during a full-scale CO2 storage project. These questions include whether a full-scale CO2 injection can expect complete mineralization on time scales similar to those observed during small-scale injections, as well as how the properties of the target formation will be altered by decades of geochemical reactions. Recently, we developed VIRTra, a vertically integrated reactive transport model specifically designed for efficient field-scale simulation of CO2 storage in reactive rocks. The present work uses this new method to explore the behavior of the water-CO2-basalt system during large-scale injection of separate-phase CO2 in a deep saline aquifer. Trends in the assembled data indicate that a high rate of CO2 dissolution into the aqueous phase results in faster mineralization. However, the time scales on which full mineralization of the injected CO2 is achieved are on the order of centuries, orders of magnitude larger than those observed in small-scale field tests. This appears to be a direct result of the increase in scale of the injection. During the injection period, changes in porosity are observed to be highly dependent on mineral reaction kinetics. Important areas of further research include the impact of mineralogy and formation water composition on the mineralization process, and the relationship between porosity and permeability in vesicular rock types.

How the sulfur dioxide in the flue gas influence microalgal carbon dioxide fixation: From gas dissolution to cells growth

Aiming at realizing efficient microalgae-based CO2 sequestration from coal-fired power plants, this study investigated the interaction between the mass transfer of SO2-contained flue gas and microalgae growth. The results indicate that the CO2 dissolution in microalgae suspension and the growth of Chlorella vulgaris could be hindered by solution acidification and oxidative molecular species produced in the conversion of bisulfite to sulfate. With the SO2 concentration increased from 0 to 400 ppm, the pH of the culture medium decreased from 7 to 2, and the SO42− concentration reached 1 g L−1, resulting in a decrement of 18.1% in the CO2 dissolution rate. Moreover, the Chlorella cells could only maintain their growth within the SO42− concentration of 800 mg L−1 accompanied by a decrement of 58% in maximum biomass concentration. The cultivation collapsed under excessive SO2 (over 400 ppm) as the plasmolysis and chloroplast decomposition occurred which severely inhibited the microalgal photosynthesis. This work provides a guide to cultivating microalgae using real flue gas.

CO2-monoethanolamine-induced oil swelling and viscosity reduction for enhanced oil recovery

The present study utilizes a microfluidic approach to investigate the effect of monoethanolamine (MEA) on increasing CO2 solubility in a light crude oil for low pressure immiscible enhanced oil recovery (EOR) operations. The CO2 microbubble area reduction over time was measured at varying MEA concentrations in oil to quantitatively estimate the effect of MEA on CO2 solubility, and as a result, its effect on gas-induced oil swelling and oil viscosity reduction. The maximum CO2 dissolution in 0.1% (v/v) MEA and 2% (v/v) MEA in oil was observed to be 77% and 86% dissolution, respectively. In addition, minor increases in CO2 dissolution rate were observed in 2% (v/v) MEA with oil when compared with 1% (v/v) MEA with oil and the control (pure oil). Furthermore, in order to test the feasibility of MEA employment in actual EOR operations, a series of immiscible CO2 flooding experiments were performed in a porous media to simulate an actual oil reservoir. In CO2 flooding experiments, the cumulative oil recovery efficiency was increased by 4% and 22% with 5% (v/v) MEA and 10% (v/v) MEA, respectively, due to the reduction of oil viscosity by CO2 dissolution. Unique phenomena such as trapping, displacement, re-filling, and drifting of oil blobs were observed during CO2 flooding. The MEA's strong effect on CO2 solubility, and as a result, its effect on various oil properties, indicates a potential for improving the recovery factor and reducing the cost of EOR operations.

Approaches and involved principles to control pH/pCO2 stability in algal cultures

Experimental cultures of both microalgae and macroalgae are commonly carried out by phycologists or environmental biologists to look into morphological, physiological, and molecular responses to aquatic environmental changes. However, the species of inorganic carbon in algae cultures is often altered by algal photosynthetic CO2 removal and/or bicarbonate utilization. The pH changes associated with altered carbonate chemistry in cultures impact physiological processes in microalgae and macroalgae even at their exponential growth phases, since extra energy is required to sustain intracellular acid–base homeostasis. Usually, pH increases during light period due to inorganic carbon uptake and utilization for photosynthesis and decreases during dark period because of respiratory CO2 release. Therefore, to obtain relevant data aimed for physiological and/or molecular responses of algae to changed levels of environmental factors, stability of pH/pCO2 in the cultures should be considered and controlled to rule out impacts of carbonate chemistry and pH changes. In this work, principles involved in changing pH processes in algal cultures are mechanistically analyzed and several approaches to control pH and pCO2 are introduced. In order to sustain stability of pH/pCO2, the principles underline the following key points: (1) maintaining the rate of photosynthetic C removal less than or equal to the rate of CO2 dissolution into the cultures which are aerated; or (2) sustaining dilute cultures with very low cell density without aeration, so that photosynthetic C removal is small enough not to cause significant pH/pCO2 changes; or (3) stabilizing the changes in micro-environments surrounding the cells or thallus. To maintain pH drift < 1% in growing typical unicellular microalgae, the recommended cell concentration ranges from 50 × 103 to 200 × 103 mL−1 with aeration (air replacement rate of ca 500–1000 mL L−1 min−1) in semi-continuous cultures of < 1 L, and it ranges from 100 to 5000 cells mL−1 for diatoms and from 100 to 100 × 103 cells mL−1 for coccolithophores in dilute cultures without aeration, respectively. For macroalgae, maintaining the thalli in flowing through- system or in semi-continuous cultures (continuously control algal biomass density) is recommended.

Quantification of solubility trapping in natural and engineered CO 2 reservoirs

Secure retention of CO 2 in geological reservoirs is essential for effective storage. Solubility trapping, the dissolution of CO 2 into formation water, is a major sink on geological timescales in natural CO 2 reservoirs. Observations during CO 2 injection, combined with models of CO 2 reservoirs, indicate the immediate onset of solubility trapping. There is uncertainty regarding the evolution of dissolution rates between the observable engineered timescale of years and decades, and the &gt;10 kyr state represented by natural CO 2 reservoirs. A small number of studies have constrained dissolution rates within natural analogues. The studies show that solubility trapping is the principal storage mechanism after structural trapping, removing 10–50% of CO 2 across whole reservoirs. Natural analogues, engineered reservoirs and model studies produce a wide range of estimates on the fraction of CO 2 dissolved and the dissolution rate. Analogue and engineered reservoirs do not show the high fractions of dissolved CO 2 seen in several models. Evidence from natural analogues supports a model of most dissolution occurring during emplacement and migration, before the establishment of a stable gas–water contact. A rapid decline in CO 2 dissolution rate over time suggests that analogue reservoirs are in dissolution equilibrium for most of the CO 2 residence time. Supplementary material: Dissolution rate for all plots and exponential function curves for scenarios A and B are available at https://doi.org/10.6084/m9.figshare.c.5476199 Thematic collection: This article is part of the Geoscience for CO 2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

Multiphase CO[formula omitted] dispersions in microfluidics: Formation, phases, and mass transfer

The dissolution and microfluidic mass transfer of carbon dioxide in water at high-pressure conditions are crucial for a myriad of technological applications, including microreactors, extractions, and carbon capture, utilization, and sequestration (CCUS) processes. In this experimental work, we use a high-pressure microfluidic method to elucidate the mass transfer process of CO2 in water at high pressure. An intriguing multiphase CO2 flow and dispersions are observed when operating at the pressure–temperature (P–T) condition close to the CO2 gas–liquid phase boundary (P=6.5MPa and T=23.5±0.5°C). We propose a series of strategies to unravel this complex multi-phase dynamics by calculating each phase's volume and mass change in a gas–liquid coexistent CO2 dispersion, estimating the possible CO2 concentration change in water, and comparing with the CO2 solubility data. Finally, we quantify the CO2 mass transfer by directly calculating the CO2 dissolution rate in water and estimating the volumetric mass transfer coefficient (kLa). The results show that the mass transfer may be influenced by the specific area (a), CO2 concentration gradient in the water slug, and the traveling speed of a dispersion.

Impact of CO2 leakage from sub-seabed carbon dioxide storage on sediment and porewater geochemistry

Sub-seabed geological CO2 storage is discussed as a climate mitigation strategy, but the impact of any leakage of stored CO2 into the marine environment is not well known. In this study, leakage from a CO2 storage reservoir through near-surface sediments was mimicked for low leakage rates in the North Sea. Field data were combined with laboratory experiments and transport-reaction modelling to estimate CO2 and mineral dissolution rates, and to assess the mobilization of metals in contact with CO2-rich fluids and their potential impact on the environment. We found that carbonate and silicate minerals reacted quickly with the dissolved CO2, increasing porewater alkalinity and neutralizing about 5% of the injected CO2. The release of Ca, Sr, Ba and Mn was mainly controlled by carbonate dissolution, while Fe, Li, B, Mg, and Si were released from silicate minerals, mainly from deeper sediment layers. No toxic metals were released from the sediments and overall the injected CO2 was only detected up to 1 m away from seabed CO2 bubble streams. Our results suggest that low leakage rates of CO2 over short timescales have minimal impact on the benthic environment. However, porewater composition and temperature are effective indicators for leakage detection, even at low CO2 leakage rates.

Experimental study on the dissolution of supercritical CO2 in PS under different agitators

Abstract In the continuous molding of microporous plastics, the polymer/CO2 homogeneous body needs to be formed in a very short time, which affects the subsequent bubble nucleation, bubble pore distribution, and growth, and is the key to the molding. It is known that the formation time of homogeneous body is shortened during the continuous molding of microporous plastics because of the agitator’s effect. However, different agitators have different effects on the dissolution rate. So, it is necessary to study not only the dissolution of gas in polymer melt under static condition but also the dissolution under the action of the agitator. In this article, the solubility and dissolution rate of supercritical CO2 in polymer melt PS at different temperatures and pressures were experimentally investigated under conical and screw agitators, and the numerical solution was also carried out.

Numerical investigations of foam-assisted CO2 storage in saline aquifers

CO2-foam injection is a promising technology for reducing gas mobility and increasing trapping within the swept region in deep brine aquifers. In this work, a consistent thermodynamic model based on a combination of the Peng-Robinson equation of state (PR EOS) for gas components with an activity model for the aqueous phase is implemented to accurately describe the complex phase-behavior of the CO2-brine system. The phase-behavior module is combined with the representation of foam by an implicit-texture (IT) model with two flow regimes. This combination can accurately capture the complicated dynamics of miscible CO2 foam at various stages of the sequestration process. The Operator-Based Linearization (OBL) approach is applied to improve the efficiency of the highly nonlinear CO2-foam problem by transforming the discretized nonlinear conservation equations into a quasi-linear form based on state-dependent operators. We first validate our simulation results for enhanced CO2 dissolution in a small domain with and without the presence of a capillary transition zone (CTZ). Then a 3D unstructured reservoir is used to examine CO2-foam behavior and its effects on CO2 storage. Simulation studies show good agreement with analytical solutions in both cases with and without CTZ. Besides, the presence of a CTZ enhances the CO2 dissolution rate in brine. Foam simulations show that foams can reduce gas mobility effectively by trapping gas bubbles and inhibit CO2 from migrating upward in the presence of gravity, which in turn improves the sweep efficiency and opens the unswept region for CO2 storage. In the long run (post-injection), with the increasing effects of dissolution, the mechanism of residual trapping, due to the presence of foam, may not be significant. This work suggests a possible strategy to develop an efficient CO2 storage technology.

Unstable Density‐Driven Convection of CO2 in Homogeneous and Heterogeneous Porous Media With Implications for Deep Saline Aquifers

AbstractDensity‐driven convection mixing has been identified to enhance CO2 trapping in deep saline aquifers storage. In this study, the dynamics of fingering instability and associated mass transfer caused by convection mixing between the movements of miscible analogue fluid pairs are investigated by magnetic resonance imaging (MRI). Two kinds of homogeneous porous media and six kinds of heterogeneous porous media with varying permeability permutations were used at ambient pressure and temperature. In homogeneous porous media, the detail analyses on the data of fingering pattern, finger number and distribution identify that the large finger sizes and high sinking velocities can be developed when the permeability up to 3.3 × 10−11 m2. In heterogeneous porous media, the sand layer first touched by downward fingers plays a dominant role in finger evolution, channeling and fingering convection mechanisms were found among these cases. Moreover, the dissolution rate characterized by Sherwood number (Shm) (enhance or inhibit fluid mixing, depending on the layout of the sand layer) was found to be independent of the local convection dissolution, such as vortex flow and finger splitting at the sand boundary with mutation permeability (enhanced fluid mixing, promoting CO2 dissolution in carbon storage). Finally, the total CO2 dissolution rate Shm in all cases was compared, Shm are at a range of 970–5,079 in homogeneous porous media, while are 190–688 in heterogeneous porous media.

Effect of Convective Mixing Process on Storage of CO2 in Saline Aquifers with Layered Permeability

Convective mixing of free-phase CO2 and brine in saline aquifers is an established technique to accelerate the CO2 dissolution process. Correct estimation of the convection onset time and rate of CO2 dissolution into brine are two crucial parameters regarding safety issues, as the timescale for dissolution corresponds to the same time over which the free-phase CO2 has a chance to leak out from the storage site. In real practice, underground formations are heterogeneous with a layered structure, but the convective mixing in heterogeneous porous media has received less attention than the homogeneous one. This study aims to develop a basic understanding of the role of layered permeability media (layered structure with variation in permeability vertically) on the behavior of convective mixing via well-controlled laboratory experiments. The effects of layering and layer properties on the rate of dissolution of CO2 in water and geometries of the formed convection fingers are studied using a precise experimental set-up with layered-permeability Hele-Shaw cell geometry. Qualitative (snapshots of convection fingers) and quantitative data (amount of the dissolved CO2 into water) are collected simultaneously for a better understanding of the process. The behavior of convection fingers (after the onset of convection) and the effects of model properties on this mixing process are also discussed.

Study on the Dissolution and Diffusion of Supercritical Carbon Dioxide in Polystyrene Melts Based on Adsorption and Diffusion Mechanism.

In order to reveal the dissolution process, the adsorption kinetics and diffusion theory are combined and used to describe the adsorption-diffusion mechanism. This can not only predict the solubility of supercritical CO2 in polymer melts but also describe two important parameters of supercritical CO2 in the dissolution process: dissolution amount and dissolution rate, which can provide a good theoretical basis for microcellular foaming. To verify the feasibility and accuracy of the theoretical calculation method, an experimental device for the volume-changing method under static condition was established. The results showed that the theoretical calculation value was in good agreement with the experimental value. In addition, the dissolution amount and dissolution rate of supercritical CO2 in three polystyrene melts with different molecular weights under different temperature and pressure conditions were measured. The results showed that the difference of polystyrene molecular weight can cause the change of dissolution rate during the dissolution process, that is, the larger the molecular weight, the slower the dissolution rate.

Influence of reservoir properties on the dynamics of a migrating current of carbon dioxide

Storage of carbon dioxide (CO2) in saline aquifers is a promising tool to stabilize the anthropogenic CO2 emissions. At the reservoir conditions, injected CO2 is buoyant with respect to the ambient fluid (brine) and spreads as a current laterally and toward the top cap rock of the aquifer, with the potential risk of a leakage into the upper aquifer layers. However, CO2 is partially soluble in brine and the resulting mixture (CO2 + brine) is denser than both starting fluids. This heavy mixture makes the configuration unstable, producing a convective flow that enhances the dissolution of CO2. Motivated by this geophysical problem, we analyze the influence of the porous medium properties on the evolution of a buoyant current that is weakly soluble with the ambient fluid. A time-dependent large-scale model [C. W. MacMinn et al., “Spreading and convective dissolution of carbon dioxide in vertically confined, horizontal aquifers,” Water Resour. Res. 48, W11516 (2012)] is used to analyze the evolution of the flow. In this work, we include additional physical effects to this model, and we investigate the role of horizontal confinement, anisotropy, and dispersion of the porous layer in the dynamics of the fluid injected. The effect of anisotropy and dispersion is accounted by changing the dissolution rate of CO2 in brine, which is obtained from experiments and Darcy simulations and represents a parameter for the model. Our results reveal that while the confinement has a remarkable effect on the long-term dynamics, i.e., on the lifetime of the current, anisotropic permeability and dispersion of the medium influence mainly the short-term behavior of the flow. Finally, we outline possible implications for the CO2 sequestration process.

Developing a Spiral-Ascending CO2 Dissolver to Enhance CO2 Mass Transfer in a Horizontal Tubular Photobioreactor for Improved Microalgal Growth

In order to enhance the CO2 dissolution rate and prolong gas–liquid contact time to improve microalgal growth, a spiral-ascending CO2 dissolver was developed to enhance CO2 mass transfer in a horiz...

Beneficial reuse of treated municipal wastewater and flue gas carbon dioxide via combined ion exchange

Combined ion exchange (CIX) treatment of wastewater effluent and ion-exchange regeneration using flue gas carbon dioxide (CO2) was investigated as a way of beneficially joining the water and energy sectors. CIX treatment removed calcium, magnesium, sulfate, nitrate, phosphate, and dissolved organic carbon from wastewater effluent. Regeneration of CIX using sodium chloride, sodium bicarbonate, hydrochloric acid, and CO2 was investigated. Carbon dioxide had a lower regeneration efficiency compared with the other regeneration solutions. Alternative CO2 regeneration conditions were evaluated to gain insight on the effects of increased gas pressure, increased contact time, and increased rate of CO2 dissolution on regeneration efficiency.