CO2 Absorption Capacity Research Articles

MPS@BWO with High Adsorption Capacity for Efficient Photocatalytic Reduction of CO2

Photocatalysis can reduce CO2 to available energy by means of light energy, which is considered to be an effective solution to alleviate energy and environmental problems. In this paper, an MPS@Bi2WO6 composite photocatalyst was prepared by in situ hydrothermal method. BWO grew on the surface of MPS, which increased the CO2 absorption capacity of the photocatalyst and improved the microstructure. Under the synergistic effect of the two aspects, BWS achieves the enhancement of light energy absorption capacity and can effectively excite electron-hole pairs. The transition electrons with high reduction ability migrate to the surface and contact with high concentrations of CO2, achieving efficient CO2 reduction under visible light. Among the photocatalysts in this paper, BWS-1 (BWO: MPS = 1:1) has efficient CO2 gas phase reduction ability under visible light, and the CO yield reaches 29.51 μmol/g. The MPS@BWO photocatalyst is a low-cost and efficient CO2 photoreduction catalyst with broad application prospects.

Investigation on CO2 capture performance of low-viscosity diamine non-aqueous absorbents with N-methyldiethanolamine regulation

In recent years, non-aqueous absorbents have attracted increasing attention due to their ability of significantly reducing sensible and latent heats in regeneration processes compared to conventional organic amine aqueous solution. But high viscosity of non-aqueous absorbents after CO2 absorption saturation became an obstacle to their industrial application. Here, a novel low-viscosity diamine non-aqueous absorbent for high-efficiency CO2 capture was proposed, in which N-methyldiethanolamine (MDEA) with steric hindrance effect was introduced as a regulator and dimethyl sulfoxide (DMSO) as a cosolvent. The effects of MDEA on CO2 capture performance of various non-aqueous absorbents and its regulation mechanism on CO2 absorbent viscosity were investigated systematically. Experimental results showed that when 25 wt% 2-(2-aminoethylamino)ethanol (AEEA) was screened as main CO2 absorption component, AEEA/MDEA/DMSO non-aqueous absorbent exhibited a high CO2 absorption capacity of 2.55 mol/kg and a fast CO2 absorption rate. Based on further mass fraction optimisation, it was found that the lowest viscosity of non-aqueous absorbents after CO2 absorption was 13.12 mPa s and the highest CO2 regeneration reached 93.5 % with AEEA and MDEA were 17.5 wt% and 12.5 wt%, respectively. 13C NMR tests showed that two characteristic peaks of carboxylated carbon appeared in CO2 products, which indicated that both amino groups on AEEA molecule were involved in CO2 absorption reaction. DFT calculations indicated that hydrogen bonding strength between MDEA and CO2 products was relatively lower than that of AEEA and CO2 products, which favored reducing absorbent saturation viscosity significantly. Thermodynamic analysis revealed that total regeneration energy consumption for 17.5 wt% AEEA/12.5 wt% MDEA/70 wt% DMSO non-aqueous absorbent was 1.72 GJ/t CO2, which was 53 % lower than that of MEA aqueous solution.

Experimental investigation of CO2 capture at high pressure using energy-efficient amino acid salt solvents

The increase in energy consumption has led to greenhouse gas emissions, specifically CO2. This has caused many researchers to explore the possibility of capturing CO2 emissions. The utilization of typical water-based solvents, such as amine solutions, poses challenges in large-scale operations owing to the substantial energy consumption associated with their regeneration process. To decrease the energy required to regenerate the solvent, new types of phase change solvents, known as lean water amino acid-based phase change solvents, were invented. This study investigated the absorption capacity of an amino acid salt made up of glutamine and potassium hydroxide in a water-based solution including N,N-dimethylformamide (DMF) as a co-solvent. The measurement of absorption capacity was conducted under elevated pressures ranging from 5 to 30 bar. Additionally, an investigation was conducted to assess the impact of DMF volumetric concentration on absorption capacity. The findings of the study indicated that augmenting both the pressure and concentration of DMF increased the capacity for CO2 absorption. This enhancement was achieved by simultaneously raising the rates of physical and chemical absorption. The results obtained from the C NMR phase analysis revealed that the solid phase had carbon bonds that were related to the absorption of CO2, whilst the upper liquid phase did not contain any CO2. This phase might readily be recycled into the absorption process without the need for regeneration. The absorption capacity of this solvent was also assessed following three absorption-reduction cycles. The results indicated a decrease in absorption capacity by only 6.6 %.

CO2 absorption performance of biogas slurry enhanced by biochar as a potential solvent in once-through CO2 chemical absorption process

Carbon capture, utilization, and storage (CCUS), offers a promising avenue for mitigating CO2 emissions, in which the big challenge is the high CO2 capture cost. A novel CCUS technology called once-through CO2 chemical absorption using biogas slurry, could potentially reduce the CO2 capture cost through decreasing the energy consumption greatly during CO2 capture. This technology, however, is constrained by the CO2 absorption capacity of biogas slurry. To enhance the CO2 capture capacity of this innovative technology, we proposed a method to enhance CO2 absorption by integrating biochar into biogas slurry. Results indicated that the CO2 absorption capacity of biogas slurry improved by biochar varied with the type of biochar adopted. Among all the investigated biochar, the wood biochar like sea buckthorn and sand willow exhibited the lowest CO2 capture enhancement, with 0.82±0.19 mmol/g and 0.81±0.30 mmol/g, respectively. Biochar from C4 plants like corn stalks and cobs demonstrated the highest enhancement, with 2.11±0.24 mmol/g and 2.47±0.86 mmol/g, respectively. The enhancement driven by C3 plant biochar like millet stalks and shells was intermediate, with 1.62±0.47 mmol/g and 1.62±0.46 mmol/g, respectively. The primary factor for promoting CO2 absorption in the biochar-based biogas slurry was the increase in pH of biogas slurry. The total pore volume of biochar was the principal material property that enhanced CO2 absorption, followed by the EC and BET surface areas of biochar. Increasing the carbonization temperature of biochar could also enhance the CO2 absorption capacity by biogas slurry. In CO2-rich biochar-based biogas slurry, CO2 primarily existed as HCO3− and carbamate. However, for the influence of the biochar's pore structure, CO2 in the CO2-rich biochar-based biogas slurry was more stable than that in CO2-rich biogas slurry.

Insight and assessment of CO2 capture using diethylenetriamine/2-(diethylamino)ethanol/n-propanol water-lean biphasic solvent: Experimental and quantum chemical calculation

Biphasic solvents hold immense promise for CO2 capture, but often struggle to maintain stable performance over long-term cyclic use. Alcohols possess low dielectric constants, which can provide protons for amine-CO2 reaction products, enhancing the regeneration performance of absorbents while maintaining stability. In this study, diethylenetriamine (DETA) + 2-(diethylamino)ethanol (DEEA) + H2O was used as the biphasic solvent, with n-propanol (PrOH) serving as the regulator to develop the DETA + DEEA + PrOH water-lean biphasic solvent. Replacing half of the water with PrOH improved the cyclic stability of the absorbent, reduced the rich phase ratio (46 %) and energy consumption (2.05 GJ·ton−1 CO2), while effectively enhanced corrosion resistance and thermal stability, confirming the feasibility of PrOH as the regulator. The detailed reaction mechanism of the absorbent for CO2 absorption was elucidated through 13C NMR and DFT calculations. Quantum chemical calculations have provided the first compelling evidence for PrOH’s involvement in the absorption reaction: PrOH stores the reaction products in the form of PrOCOOH/PrOCOO−. By regenerating DETA, it restores its CO2 absorption capacity. Through polarity and hydrogen bonding, the reaction products aggregate in one phase, enhancing CO2 loading. In summary the PrOH regulated water-lean biphasic solvent presents a highly promising absorbent for industrial use.

Hybrid solvent loop CO2 capture process for zero-emission hydrogen production

Natural gas reforming with CO2 capture is expected to play a crucial role in producing low-carbon hydrogen under the net-zero emission scenario. This work focuses on optimizing the CO2 capture processes for zero-emission hydrogen production, targeting an ultra-high CO2 capture ratio of 99.9 % from the shifted syngas. We present a novel hybrid solvent loop CO2 capture process that enhances capture efficiency by overcoming the inherent trade-off between CO2 absorption kinetics and capacity in conventional processes. This is achieved by utilizing two independent solvent loops, each operating within its optimal performance range. In the lower section of the absorber, a high-capacity solvent, aqueous potassium carbonate, is used to leverage the high CO2 partial pressure. In the upper section, a fast-kinetic solvent, aqueous monoethanolamine, is employed to reduce CO2 concentration to 100 ppm. The conventional process, split-flow process with a multi-pressure stripper, and the hybrid solvent loop process are modeled in Aspen Plus® and compared. Our results demonstrate that the proposed hybrid solvent loop configuration outperforms conventional methods, significantly reducing the CO2 regeneration duty by 25 % and total equivalent work by 16 %. This process enhances the feasibility of low-carbon hydrogen production and supports the goal of achieving net-zero emissions.

Carbon dioxide sequestration through mineralization from seawater: The interplay of alkalinity, pH, and dissolved inorganic carbon

Marine carbon dioxide removal technologies rely on the equilibration of the seawater with atmospheric CO2, where a pH increase can facilitate carbon dioxide removal either through increased absorption capacity of CO2, or precipitation of minerals. Here, we focus on explicitly defining the governing factors that influence seawater alkalinity with respect to CaCO3 mineralization and atmospheric CO2 uptake. We utilize an electrochemical setup and different water types, from near-shore Mediterranean seawater as well as Red Sea Salt water. The setup allows us to separate mineralization from alkalinity enhancement via an electrochemical membrane cell, and a second compartment with controlled environment, where the interplay of ion concentration, precipitation, pH, DIC concentration, and total alkalinity are evaluated. The effect of sparging additional carbon dioxide before, and after the precipitation of CaCO3 was evaluated while utilizing both a mild pH swing (from, ∼8.3 to ∼9.5), and a larger pH swing (from, ∼8.3 to ∼10.2). A thermodynamic model is presented defining the energy consumption to increase the pH, and the influence of Mg thereon is explicated. Furthermore, we detail theoretical aquatic chemistry simulations via PHREEQC to rationalize the observed intricate dynamics of the carbonate system in seawater. We end with a discussion of the implications of total alkalinity, pH, salt complexation, and carbon uptake capacity relevant to of all ocean alkalinity enhancement and marine based carbon dioxide removal systems, concluding that the carbon uptake capacity of water returned to the ocean must be verified in such technologies

Self-acceleration effect of Mn/Ce-modified carbide slag in CO2 absorption for CaO/CaCO3 energy storage

Carbide slag, a solid waste from the chlor-alkali industry, can be used for CO2 capture and energy storage. Herein, the cyclic reaction activity of Mn/Ce-modified carbide slag under energy storage conditions was studied. The Mn/Ce-modified carbide slag shows energy storage density over 2100 kJ/kg and CO2 absorption capacity of 0.52 g CO2/g sorbent after 30 cycles. Notably, both carbonation and calcination rates are accelerated with the number of cycles. This self-acceleration effect is related to the evolution of oxygen vacancy concentration and texture structure of Mn/Ce-modified carbide slag during the cycles. In the cycles, CaMnO3 in the Mn/Ce-modified carbide slag reacts with the formed CaCO3 in the carbonation stage to produce more Ca2MnO4. The formation of Ca2MnO4 increases oxygen vacancies in the Mn/Ce-modified carbide slag, significantly enhancing its CO2 adsorption capacity. Thus, the release of the increased CO2 in the calcination stage generates more pores in the 10–100 nm diameter range in the modified carbide slag, facilitating rapid carbonation. Thus, the Mn/Ce-modified carbide slag exhibits good prospect for CaO/CaCO3 thermochemical energy storage.

Enhancement of CO2 removal from flue gas in an oscillatory baffled column using potassium carbonate solution

One of the efficient methods for reducing CO2 emissions from flue gas streams in oil refineries and power plants is the CO2absorption process using alkali solution. Potassium carbonate (K2CO3) solution, as CO2 absorbent, was used in the present study due to its high CO2 absorption capacity. However, K2CO3 has a drawback which is represented by its slow reaction with CO2. To overcome this issue, an oscillatory baffled column (OBC) was utilized as a contactor to maintain a high degree of mixing in the CO2 absorption system and thereby increasing the reaction rate between K2CO3 and CO2 as well as enhancing the mass transfer rate. In this study the effect of different operation conditions of the process namely; inlet flue gas flow rate (15 % (v/v) CO2 balanced with N2) and oscillation conditions on CO2 absorption in a semi-batch OBC were investigated. The experiments were performed with range of modified Reynolds Number of Oscillation (Reo′ = 0⎼1450) and aeration rates (0⎼1 vvm) using K2CO3 (100 g/L, 0.72 M)0.1.8–3.5-fold of enhancement of CO2 absorption rates was achieved by using OBC with respect to that obtained by baffled column (BC) (only baffles without oscillation) and plane bubble column (PBC) (without baffles and oscillation), respectively.The use of K₂CO₃ as a solvent in an oscillating reactor (OBR) to remove CO₂ represents a new method due to the high reactivity of K₂CO₃ with CO₂, forming stable bicarbonate and carbonate compounds. OBR's enhanced mixing capabilities improve mass transfer rates and reaction efficiency, allowing for more effective CO2 capture compared to conventional reactors. This combination leverages the strengths of both the chemical reactivity of K₂CO₃ and the mechanical benefits of OBR, potentially leading to more efficient and scalable CO2 removal processes.

Characterization of Humic Acid Salts and Their Use for CO2 Reduction

The European Union aims to be climate neutral by 2050. To achieve this ambitious goal, net greenhouse gas emissions must be reduced by at least 55% by 2030. Post-combustion CO2 capture methods are essential to reduce CO2 emissions from the chemical industry, power generation, and cement plants. To reduce CO2, it must be captured and then stored underground or converted into other valuable products. Apromising alternative for CO2 reduction is the use of humic acid salts (HASs). This work describes a process for the preparation of potassium (HmK) and ammonium (HmA) humic acid salts from oxidized lignite (leonardite). A detailed characterization of the obtained HASs was conducted, including elemental, granulometric, and thermogravimetric analyses, as well as 1H-NMR and IR spectroscopy. Moreover, the CO2 absorption capacity and absorption rate of HASs were experimentally investigated. The results showed that the absorption capacity of the HASs was up to 10.9 g CO2 per kg. The CO2 absorption rate of 30% HmA solution was found to be similar to that of 30% MEA. Additionally, HmA solution demonstrated better efficiency in CO2 absorption than HmK. One of the issues observed during the CO2 absorption was foaming of the solutions, which was more noticeable with HmK.

Fundamental physicochemical properties, intermolecular interactions and CO2 absorption properties of binary mixed solutions of monoethanolamine + diethylenetriamine

This work presents experimental data on the density (ρ), viscosity (η), and surface tension (γ) of monoethanolamine (MEA), diethylenetriamine (DETA), and their binary mixed solutions across 298.15–318.15 K. Using these physicochemical data, the work also explored properties like excess molar volume (VmE) and viscosity deviation (Δη) of the solutions. The experimental results were modeled using the Jouyban-Acree model, McAllister four-body model, and Redlich-Kister (R-K) equation. The application of these parametric models confirmed strong intermolecular interactions (The length (1.911 Å) and energy (HF value: −2237.54 kJ/mol and Des: −21.61 kJ/mol) of hydrogen bond) within the MEA + DETA binary mixed solutions. Spectroscopic analyses, including Raman and nuclear magnetic resonance hydrogen spectroscopy, revealed the presence of intermolecular hydrogen bonding (OH⋯N(H2)) in the MEA + DETA binary mixed solutions. Lastly, the CO2 absorption capacity of the solutions was experimentally studied, providing a theoretical foundation and reference data for future experiments and process design of CO2 capture.

Enhanced CO2 capture by functionalization of SBA-15 with APTES and l-lysine

In this study, amine-based CO2 sorbents were synthesized after functionalizing SBA-15 mesoporous materials. Mesoporous SBA-15 was characterized and functionalized by APTES as an alkanolamine, L-lysine as an amino acid and a combination of both. CO2 adsorption tests were performed at 1.6 and 2 bar to estimate the carbon dioxide (CO2) uptake on the sorbents. As expected, CO2 adsorption capacity (mmol/g) increases with pressure. Based on the elemental analysis of the sorbents and the results of Fourier transform infrared spectroscopy (FTIR), a proposal was made of the possible chemical reactions that may occur in order to describe the experimental results. It is important to mention that the pretreatment prior to the CO2 adsorption tests plays a key role for the application of amine-functionalized mesoporous silica. The presence of water conditions the formation of carbonic acid and carbonate adsorbed on the surface and, consequently, the CO2 adsorption capacity of the sorbent. APTES and l-lysine loaded onto mesoporous SBA-15 exhibited the highest CO2 adsorption capacity (4.53 mmol/g) at 2 bar and room temperature. After reloading the sorbents with APTES and Lysine, no improvements in the CO2 absorption capacity were observed.

A novel ionic liquids phase change absorption system for carbon dioxide capture and utilization

In order to achieve low cost, and reduce energy consumption during regeneration, a novel ionic liquid phase change absorbent composed of tetraethylenepentamine [TEPA] imidazole [Im] and diethylene glycol dimethyl ether (DGME) and water was designed for CO2 capture applications. The absorbent [TEPAH][Im]+DM+H2O can achieves a CO2 absorption capacity of 2.08 mol CO2/mol ILs, the rich phase volume accounts for 15.6 vol%, and the mass fraction of CO2 is 99 %, this greatly reduces the regenerative volume of the absorption system, showing the potential of energy saving and emission reduction. After five absorption–desorption cycles, the regeneration efficiency of the system remained above 96 %. The CO2 capture mechanism was analyzed using both 13C NMR spectroscopy and density functional theory (DFT) calculations to elucidate its underlying processes. The cation [TEPAH]+ and the anion [Im]- each undergo a reaction with CO2 to produce carbamate, followed by hydrolysis of carbon dioxide to yield carbonate. The absorption system’s phase transition behavior primarily arises from variations in CO2 product solubility across solvents. Moreover, the ionic liquid facilitated the conversion of CO2 into quinazoline-2,4 (1H, 3H)-dione with a remarkable yield of 98 %. Even after five cycles, the ILs maintained substantial catalytic activity.

Experimental study on CO2 absorption in aqueous solutions and water–oil emulsions of TEA and blended MEA/DEA–TEA

ABSTRACT The CO2 absorptions in aqueous solutions and water-in-oil (W/O) emulsions of TEA, MEA–TEA, and DEA–TEA were investigated. By applying an experimental setup, the effects of reactant concentration (0.25–1 M for TEA, 0.1–0.3 M for MEA/DEA), temperature (15–35°C), volume fraction of the dispersed phase (0.4–0.6), and pressure (100–400 kPa) on capacity and rate of CO2 absorption were measured and compared. The CO2 absorption capacity in a TEA solution with a low/medium concentration (0.25–0.5 M) is more than the theoretical value while these values are approached to each other in the high concentration (1 M). The CO2 absorption capacity of blended solutions (MEA/DEA–TEA) is higher than that of the TEA solution. By increasing the temperature, the CO2 absorption capacities of the TEA and blended solutions are decreased by increasing the temperature. For the emulsion solutions, increasing the volume fraction of the dispersed phase causes a decrement in the capacity of absorption. In the low concentration of MEA/DEA (0.1 M), the aqueous solution has a higher absorption capacity than that of the emulsion while this trend is reverse in the high concentration of MEA/DEA (0.2–0.3 M). The CO2 absorption rates of emulsions are higher than the rates of their corresponding aqueous solutions. For the TEA solutions, the rate of CO2 absorption is controlled by the reaction rate while the shuttle mechanism enhances the absorption rate for the blended solutions. The CO2 absorption capacity and rate for the TEA and blended solutions are increased by pressure while this increment is more significant for the emulsions.

A study on degradation and CO2 capture performance of aqueous amino acid salts for direct air capture applications

AbstractWe have previously proposed amino acid salts solutions as potential absorption liquids for direct air capture (DAC) of CO2 from the atmosphere. However, little is known about their relevant CO2 solubilities, CO2 mass transfer rates, and susceptibility to oxidative and thermal degradation under conditions relevant to DAC. We report here on the overall solubility of CO2 and CO2 mass transfer rates into a series of amino acid salts solutions. Additionally, the robustness of various amino acid salt solutions to thermal and oxidative degradation has been assessed.CO2 absorption rates into the amino acid salts solutions were observed to be in the same order of magnitude as aqueous monoethanolamine (MEA), with sarcosinate and lysinate solutions providing the fastest and slowest CO2 mass transfer rates at 25°C, respectively. Degradation data revealed that all amino acid salt solutions investigated in this study displayed elevated rates of thermal degradation at both 120 and 150°C relative to MEA. The opposite trend was observed with respect to oxidative degradation where all amino acid salt solutions showed a greater resistance to oxidative degradation than that observed for MEA under the conditions investigated here. Considering the degradation, CO2 absorption capacity, and CO2 mass transfer rate data, we propose the potassium salts of proline and sarcosine as the most promising amino acid salts (of those considered here) for further evaluation in DAC processes. Overall, this study provides valuable insight into the suitability of various amino acid salt solutions as absorption liquid for DAC. © 2024 The Author(s). Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Two Different Pathways from CO2 to HCO3− in Aqueous Solutions of Arginine Sodium Salt

AbstractAmino acids and their salts are amine compounds with great potential for the chemical absorption of CO2 via the amine method. The CO2 absorption properties of various amino acids and their salts have been previously reported. However, the detailed reaction mechanism of CO2 with basic amino acids in aqueous solutions has not yet been clarified. In this study, we focused on arginine (Arg), which has the highest basicity among the standard amino acids, and its monohydrochloride (ArgCl) and sodium (NaArg) salts for the dissolution of CO2 in the aqueous solutions of Arg, ArgCl, and NaArg. CO2 was chemically dissolved in aqueous Arg and NaArg solutions but not in the aqueous ArgCl solution. One‐dimensional 1H and 13C and two‐dimensional 1H‐13C heteronuclear multiple bond correlation nuclear magnetic resonance spectroscopy indicated that the final products in the aqueous Arg and NaArg solutions were protonated Arg and HCO3−. HCO3− was formed from both CO2‐bonded Arg/Arg− and CO32− intermediates in the aqueous NaArg solution but only from the CO2‐bonded Arg/Arg− intermediate in the aqueous Arg solution. In addition to their high environmental and biological compatibility, Arg and NaArg exhibit high CO2 absorption capacity, demonstrating their potential for practical use as naturally derived CO2 chemical absorbents.

Study on Shipboard Carbon Capture Technology with the MEA-AMP-Mixed Absorbent Based on Ship Applicability Perspective.

Ocean-going ships powered by diesel engines were the main source of CO2 emissions in the marine environment, and it was imperative to study shipboard carbon capture technology. Based on this, the whole process of CO2 absorption and desorption was studied with a mixed amine (MEA + AMP). The effective cycle time, CO2 absorption capacity, desorption efficiency, energy consumption, foaming and volatilization characteristics, and other key parameters were compared and analyzed under the conditions of required capture efficiency by ships. The MEA20% + AMP10% solution showed good CO2 absorption performance. At 80% capture efficiency, the desorption efficiency was more than 50%. The absorption capacity was close to that of the MEA30% solution, and the cycle time was basically the same. The effective cycle time under the reaction time of 2 s was also determined, which was an important parameter for setting the desorption frequency and had a great effect on reducing the desorption energy consumption. This work can provide an important reference value for the real ship application of carbon capture devices.

Efficient and eco-friendly carbon dioxide capture with metal phosphate catalysts in monoethanolamine solutions

Efficient and eco-friendly carbon dioxide capture with metal phosphate catalysts in monoethanolamine solutions

SYNTHESIS AND CHARACTERIZATION OF 2-(METHYLAMINO)ETHANOL-BASED DEEP EUTECTIC SOLVENTS FOR CO2 CAPTURE

In recent years, deep eutectic solvents (DESs) have attracted the interest of many researchers for application in a wide range of industrial and scientific fields, including carbon dioxide (CO2) capture. DESs exhibit favourable solvent properties for CO2 removal applications; hence, they have become promising alternatives to common amine solutions and ionic liquids (ILs). In this context, a novel DES was synthesised by mixing 2 (methylamino)ethanol (2-MAE) as a hydrogen bond donor with choline hydroxide (ChOH) as a hydrogen bond acceptor with a molar ratio of ChOH:2-MAE of 1:1. The solubility of CO2 in the prepared systems was determined and characterised before and after CO2 absorption by measuring their physicochemical properties (density and viscosity) and analysing their FTIR spectra. The results showed that the DES and 2M DES aqueous solutions exhibited CO2 absorption capacities comparable to those of other reported DESs. These physicochemical properties were comparable to those reported in the literature. Besides, the FTIR analysis of the studies systems after absorption indicates the formation of carbamate.

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.