Experimental study on the cyclic mineralization of CO2 enriched phase after absorption by a novel biphasic absorbent composed of DEEA and AEP | Scientific Reports

Scientific Reports volume 14, Article number: 26759 (2024) Cite this article

Metrics details

The high energy consumption of Carbon Capture Utilization and Storage(CCUS) promotes the research of integrated absorption and mineralization technology. A novel DEEA/AEP biphasic absorbent is used to absorb \(\hbox {CO}_{2}\). After phase separation, only one phase enriched with the absorption product is sent into the mineralization system, then reacts with \(\hbox {Ca(OH)}_{2}\) to produce \(\hbox {CaCO}_{3}\) at normal temperature and pressure. The effects of temperature, Ca/C and dispersion of the system were investigated, and cyclic utilization experiment was also conducted. The process was characterized and analyzed by Thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and nuclear magnetic resonance (13C NMR). The results showed that at 50 \(^{\circ }\)C, Ca/C = 1, the extent of mineralization of \(\hbox {CO}_{2}\)-enriched phase mineralization was 95.73% after ultrasonic treatment for 30 min. During 6 cycles, the volume percentage of \(\hbox {CO}_{2}\)-enriched phase could be maintained at 52–55%, and the \(\hbox {CO}_{2}\) load was 11.92mol/L. The results above indicate that the \(\hbox {CO}_{2}\)-enriched phase mineralization technology after absorption by biphasic absorbent can effectively capture \(\hbox {CO}_{2}\), realize recycling, and reduce CCUS energy consumption.

The data from the “Statistical Review of World Energy 2023”1 indicates that as of 2022, fossil fuels accounted for 82% of global primary energy consumption, and the combustion of fossil fuels resulted in the most significant emissions of carbon dioxide, which is the primary cause of greenhouse effect2. In 2023, the International Energy Agency (IEA) released the “\(\hbox {CO}_{2}\) Emission in 2023”3, stating that in 2023, \(\hbox {CO}_{2}\) emissions related to energy reached 37.4 Gt , an increase of 1.1%. This reached the highest historical emissions. Among them, \(\hbox {CO}_{2}\) emissions from energy combustion accounted for more than 65% of the increase in 2023. Currently, Carbon Capture Utilization and Storage (CCUS) technology offers a pathway to achieving “near-zero” emissions of fossil energy by capturing and storing carbon dioxide from flue gas4,5,6. Carbon capture is located at the upstream of the core technology chain of CCUS and is a crucial link affecting the effectiveness of CCUS7. Currently, there are three typical carbon capture approaches: pre-combustion carbon capture, post-combustion capture (PCC), and oxyfuel combustion8. Post-combustion carbon capture (PCC) stands out as the leading technology for \(\hbox {CO}_{2}\) capture from coal-fired flue gas, owing to its maturity9,10. It can be classified based on its separation methods, including chemical absorption3, membrane separation11,12, solid adsorption13, and low-temperature condensation14. Among these, the chemical absorption method, especially using MEA, demonstrates rapid absorption rates and has shown promising results in both experiments and industrial applications. However the substantial energy consumption during the regeneration process significantly elevates the electricity expenses of coal-fired power plants by 70–100%15.

To lessen energy consumption during absorbent regeneration and tackle the dilemma of single-component amines struggling to achieve both high absorption rates and capacities simultaneously, prior research has extensively investigated mixed amine absorption of \(\hbox {CO}_{2}\). This has spurred the development of biphasic amine absorbents. The absorption principle of biphasic amine absorbents involves blending different primary or secondary amines with tertiary amines in certain proportions. The resulting absorbent combination can achieve both high absorption rates and capacities. Biphasic absorbents exhibit the behavior of phase separation after \(\hbox {CO}_{2}\) absorption, concentrating \(\hbox {CO}_{2}\) in the \(\hbox {CO}_{2}\)-enriched phase. By regenerating only the \(\hbox {CO}_{2}\)-enriched phase, the amount of solution entering the regeneration tower is reduced, thereby decreasing the sensible heat and latent heat of vaporization during the regeneration process and lowering the solvent regeneration energy consumption16,17. Marco Aleixo et al.18 found that compared to a single 30 wt% MEA solution, using a liquid-liquid biphasic absorbent reduced the regeneration energy consumption from 3.7 GJ/t \(\hbox {CO}_{2}\) to 2.33 GJ/t \(\hbox {CO}_{2}\). Xu et al.19, Pinto et al.20, You et al.21, Liu et al.22 studied the absorption load, \(\hbox {CO}_{2}\)-enriched phase volume fraction, and regeneration energy consumption of biphasic amine absorbents DEEA+BDA, DEEA+MAPA, DEEA+DETA, and DEEA+AEEA, respectively. They found that most of the carbamate, the product of \(\hbox {CO}_{2}\) absorption, concentrated in one phase, and compared to traditional 30% MEA amine solvent, \(\hbox {CO}_{2}\)-enriched phase regeneration significantly reduced regeneration energy consumption. Pinto’s20 research data showed that the energy consumption during regeneration was 2.2–2.4 GJ/t \(\hbox {CO}_{2}\). Wang et al.23, heated the \(\hbox {CO}_{2}\)-enriched phase after absorption reaction for regeneration and, combined with Aspen Plus simulation results, confirmed that regenerating only the \(\hbox {CO}_{2}\)-enriched phase reduced sensible heat and latent heat of vaporization by 80% and 75%, respectively. However, these methods are based on thermal desorption, which still requires raising the desorption temperature to above 120 \(^{\circ }\)C, resulting in limited energy consumption reduction. Moreover, the high temperature during the heating process exacerbates equipment erosion and amine decomposition, leading to increased equipment operating costs24 and amine loss.

In recent years, researchers have proposed an integrated \(\hbox {CO}_{2}\) absorption and mineralization technology (IAM)25, which converts \(\hbox {CO}_{2}\) in the rich liquid into carbonate minerals through carbonation reactions. The reaction between calcium ions and \(\hbox {CO}_{2}\) to form \(\hbox {CaCO}_{3}\) can be carried out at room temperature and pressure16. So compared to traditional thermal regeneration, it can reduce the sensible heat and latent heat generated at 120 \(^{\circ }\)C, thus achieving both reduced regeneration energy consumption and \(\hbox {CO}_{2}\) storage26,27. So far, numerous scholars have conducted extensive research on the reaction mechanism, key influencing factors, and regeneration energy consumption of \(\hbox {CO}_{2}\) mineralization processes. Sangwon et al.28 discovered that the addition of \(\hbox {Ca(OH)}_{2}\) to MEA solution saturated with \(\hbox {CO}_{2}\) can lead to the formation of Ca\(\hbox {CO}_{3}\) to sequester \(\hbox {CO}_{2}\). Zhang et al.5 observed that employing an MEA and \(\hbox {Ca(OH)}_{2}\) solution yielded a \(\hbox {CO}_{2}\) capture amount of 0.98 mol/L. Following 10 cycles of absorption experiments, the solution maintained a mineralization extent of 78.38%, effectively regenerating the MEA solution. Ji et al.29 studied the effects of different concentrations of amines and \(\hbox {Ca(OH)}_{2}\) on the IAM process. It was found that an increase in amine concentration and \(\hbox {Ca(OH)}_{2}\) concentration is beneficial for \(\hbox {CO}_{2}\) absorption. Under the condition of 0.5 mol/L amine and 1 mol/L \(\hbox {Ca(OH)}_{2}\), the mineralization rate of PZ can reach 98%, and the amine loss in the generated \(\hbox {CaCO}_{3}\) is almost zero. ZHANG et al.30 studied the absorption-mineralization integrated process of five amines (MEA, MDEA, PG, MEA/ MDEA, and MDEA/ PG) and found that \(\hbox {Ca(OH)}_{2}\) can effectively fix \(\hbox {CO}_{2}\) in solutions loaded with five kinds of \(\hbox {CO}_{2}\), with the optimal ratio being Ca:C = 1:1. Under the optimal reaction conditions, the desorption rates of the five solutions are 85.31%, 81.15%, 72.57%, 82.79%, and 73.72%, respectively.However, the mineralization processes in the above studies usually involve sending the entire \(\hbox {CO}_{2}\)-enriched solution into the regeneration tower for mineralization, which imposes higher demands on the mineralization system’s equipment, thereby increasing the scale and energy consumption. Therefore, reducing the amount of solution entering the mineralization system while ensuring the absorption effectiveness is a key strategy for effectively lowering the energy consumption in cyclic absorption and regeneration. Mixing primary or secondary amines with tertiary amines not only overcomes the limitations of single-component amines that cannot simultaneously achieve high absorption rates and capacities, thereby enhancing \(\hbox {CO}_{2}\) absorption performance, but also facilitates phase separation after absorption, concentrating \(\hbox {CO}_{2}\) in one phase and reducing the volume of \(\hbox {CO}_{2}\)-enriched solution.

However, existing literature provides limited research on the phase separation of biphasic absorbents after \(\hbox {CO}_{2}\) absorption and the subsequent mineralization of the \(\hbox {CO}_{2}\)-enriched phase. Therefore, building on the research group’ s previous work on calcium-based adsorbents for cyclic \(\hbox {CO}_{2}\) absorption14, this paper proposes an innovative technology for the mineralization of the \(\hbox {CO}_{2}\)-enriched phase after biphasic absorbent \(\hbox {CO}_{2}\) absorption. This technology utilizes DEEA (2-diethylaminoethanol) as a phase separator, which is mixed with AEP (N-aminoethylpiperazine) and H\(_{2}\)O to create a liquid-liquid biphasic absorbent. During \(\hbox {CO}_{2}\) absorption, the absorption products concentrate in one phase, and only the \(\hbox {CO}_{2}\)-enriched phase, containing the concentrated absorption products, is sent into the regeneration system. This significantly reduces the volume of solution required for regeneration. By exclusively sending the \(\hbox {CO}_{2}\)-enriched phase into the mineralization regeneration tower , this method not only facilitates \(\hbox {CO}_{2}\) mineralization at lower temperatures, directly sequestering \(\hbox {CO}_{2}\) as \(\hbox {CaCO}_{3}\) and avoiding the energy consumption associated with thermal regeneration, but also significantly reduces the equipment requirements and energy consumption for mineralization.

This study thoroughly investigates the mineralization performance and cyclic regeneration stability of the \(\hbox {CO}_{2}\)-enriched phase derived from the proposed biphasic absorbent, composed of 50 wt% DEEA, 25 wt% AEP, and 25 wt% H\(_{2}\)O, under various temperatures, \(\hbox {Ca(OH)}_{2}\) addition ratios, and ultrasonic treatment conditions. The study examines the changes in mineralization performance under different conditions and their underlying causes. Through repeated experiments involving \(\hbox {CO}_{2}\) absorption, phase separation, mineralization of the \(\hbox {CO}_{2}\)-enriched phase, and cyclic absorption with the mixed solvent, the study explores the variations in \(\hbox {CO}_{2}\) absorption and mineralization desorption performance throughout the cycles. The findings confirm the feasibility and stability of the proposed biphasic amine absorbent for \(\hbox {CO}_{2}\) enrichment and subsequent mineralization, offering a viable solution for further reducing the energy consumption of CCUS technology.

During the research process, the mineralization of \(\hbox {CO}_{2}\)-enriched phase after \(\hbox {CO}_{2}\) absorption of DEEA-AEP mainly includes the following processes: \(\hbox {CO}_{2}\) absorption, \(\hbox {CO}_{2}\) mineralization, and regeneration of biphasic absorbents, involving the primary chemical reactions as shown in Table 1 .

The biphasic amine absorbent is composed of primary or secondary amines mixed with tertiary amines in certain proportions, and the primary and secondary amines follow a zwitterionic mechanism with an amphoteric ion (\(\hbox {R1R1NH}^{+}\hbox {COO}^{-}\)) as an intermediate5. CAPLOW31 first proposed the reaction mechanism of primary and secondary amines. Taking primary amines as an example, as shown in Eqs. (1)31, (2)32, and (3)33 in Table 1, during the reaction process, the lone pair electrons of the nitrogen atom in primary amines react with surrounding carbon atoms to form zwitterions, followed by deprotonation reactions of the hydrogen atoms connected to the nitrogen atom and the amine31, resulting in carbamate. The reaction proceeds in two steps, hence also referred to as a two-step reaction mechanism34.

Unlike primary or secondary amines, tertiary amines have all three hydrogen atoms on the nitrogen atom substituted by alkyl groups, lacking active hydrogen atoms, and therefore cannot directly react with the carbon atom on \(\hbox {CO}_{2}\)35. Hence, researchers generally believe that the reaction between tertiary amines and \(\hbox {CO}_{2}\) follows an alkaline catalytic mechanism, as shown in Eq. (4)36,37, where tertiary amines act as catalysts during the absorption of carbon dioxide, facilitating the reaction of H\(_{2}\)O with \(\hbox {CO}_{2}\).

\(\hbox {CO}_{2}\) mineralization desorption and absorbent regeneration processes are based on the absorption reaction32. In the system, \(\hbox {Ca(OH)}_{2}\) undergoes a reaction first (Eq. (5))30, partially dissolving to generate \(\hbox {Ca}^{2+}\) and \(\hbox {OH}^{-}\), which react with protonated amines produced during the absorption process, facilitating the regeneration of amines, as shown in Eqs. (8)33 and (9)21. Simultaneously, \(\hbox {OH}^{2+}\) reacts with produced during tertiary amine absorption to generate and H\(_{2}\)O, as shown in Eq. (6)30. This reaction consumes and thereby promotes the hydrolysis regeneration reaction of carbamate (Eq. (3))33. Finally, the \(\hbox {Ca}^{2+}\) generated in Eq. (5) and the produced in Eq. (6) undergo carbonation reaction to form calcium carbonate, as shown in Eq. (7)30.

Figure 1 illustrates the schematic diagram of the absorption, mineralization and amine regeneration processes using DEEA and AEP as representative biphasic amine absorbents. On the left side of the figure, the absorption, regeneration, and \(\hbox {CO}_{2}\) carbonation processes of DEEA are depicted. DEEA acts as a catalyst during the process, converting the incoming \(\hbox {CO}_{2}\) and H\(_{2}\)O into protonated DEEA, and . Upon addition of \(\hbox {Ca(OH)}_{2}\), \(\hbox {Ca}^{2+}\) react with and to form \(\hbox {CaCO}_{3}\) precipitates, while protonated DEEA amines are regenerated back to DEEA under the influence of \(\hbox {OH}^{-}\). On the right side of the figure, the absorption, regeneration, and \(\hbox {CO}_{2}\) carbonation processes of AEP are illustrated. Initially, AEP transfers \(\hbox {CO}_{2}\) to zwitterions through reactions, and then zwitterions combine with AEP to form protonated AEP amines and carbamate. After \(\hbox {CO}_{2}\) is transferred to carbamate, hydrolysis occurs, resulting in bicarbonate. Finally, by adding \(\hbox {Ca}^{2+}\), \(\hbox {CO}_{2}\) is fixed in \(\hbox {CaCO}_{3}\) precipitates, while protonated AEP amines are regenerated back to AEP under the influence of \(\hbox {OH}^{-}\). Carbon tracking is shown in green in Fig. 1.

Schematic diagram of amine absorption of \(\hbox {CO}_{2}\), cycling, and regeneration principle.

After the two types of amines absorb \(\hbox {CO}_{2}\) through different mechanisms, carbon is fixed into \(\hbox {CaCO}_{3}\) precipitate by adding \(\hbox {Ca(OH)}_{2}\), while simultaneously achieving amine regeneration in this process. From the carbon tracking in the diagram, it can be observed that by forming intermediate products such as carbamate, bicarbonate, and carbonate, the DEEA-AEP-H\(_{2}\)O solution can absorb \(\hbox {CO}_{2}\) gas, transport it, and then fix it into \(\hbox {CaCO}_{3}\), while also achieving amine regeneration.

The DEEA (> 99.99%) and AEP (> 99.99%) used in the experiment were purchased from Aladdin. Dilute sulfuric acid (0.5 mol/L) used for titration was obtained from Aladdin. Analytical grade \(\hbox {Ca(OH)}_{2}\) was purchased from Bideerman Biotech. \(\hbox {CO}_{2}\) and N\(_{2}\) were supplied by Sanhe Gas Company. Deionized water was used in the laboratory.

The experiment utilized a thermogravimetric analyzer (STA-449, Netzsch Instruments GmbH, Germany) to analyze the composition and content of the solid products after mineralization. An aluminum oxide crucible measuring 6.8 \(\times\) 4 mm was used, with nitrogen as a protective gas at a flow rate of 20 ml/min and nitrogen as a purge gas at a flow rate of 60 ml/min. X-ray diffraction analysis (Rigaku SmartLab SE, Japan) was conducted on the solid products to identify the presence of \(\hbox {CaCO}_{3}\) and \(\hbox {Ca(OH)}_{2}\). The diffraction conditions were as follows: Cu target, maximum voltage of 60 kV, maximum current of 60 mA, scanning angle from 10 \(^{\circ }\) to \(80^{\circ }\), and scanning speed of 10 \(^{\circ }\)/min. Scanning electron microscopy (SEM) (ZEISS GeminiSEM 300, Germany) was employed to analyze the morphology of the solid products after mineralization. The products were directly adhered to conductive adhesive for sample preparation, and gold sputtering was performed to enhance conductivity. The test mode was secondary electron imaging, with an accelerating voltage (EHT) of 3.00 kV and a working distance (WD) of 6.0 mm to observe the morphology of the mineralized products. Carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) was used for qualitative analysis of the substances in each phase of the solution after absorption separation, employing a BRUKER AVANCE 400 MHz instrument. Heavy water (D\(_{2}\)O) was added to the samples for locking, and one-dimensional 13C spectra were recorded, with the data processed using MestReNova software. A gas analyzer (GXH-510, Beijing Xibi Instruments Co., Ltd.) was utilized to monitor the volume concentration of \(\hbox {CO}_{2}\) during the absorption and mineralization processes. A water-bath ultrasonic device (CR-009S, Shenzhen Chunlin Ultrasonic Technology Co., Ltd., with an ultrasonic power of 80 W and a frequency of 40 kHz) was employed to treat the solution to observe the impact of dispersion on the mineralization process.

The schematic diagram for the \(\hbox {CO}_{2}\) absorption experiment and mineralization experiment is illustrated in Fig. 2 In the \(\hbox {CO}_{2}\) absorption experiment, \(\hbox {CO}_{2}\) and N\(_{2}\) are introduced into the mixing tank at flow rates of 150 sccm and 850 sccm, respectively. After thorough mixing, the gas mixture is fed below the liquid surface of the scrubbing bottle to saturate it and simulate flue gas. The simulated flue gas exiting the scrubbing bottle is then introduced into the two-phase amine absorbent in the reaction kettle. The absorbent used in the experiment is a 100 ml mixed solution prepared according to the ratio of 50 wt% DEEA, 25 wt% AEP, and 25 wt% deionized water. The temperature for absorption is set between 30 and 70 \(^{\circ }\)C using a constant temperature magnetic stirrer, with a stirring speed of 500 r/min. The \(\hbox {CO}_{2}\) absorption reaction is considered complete when the \(\hbox {CO}_{2}\) concentration detected by the fuel gas analyzer reaches 15%, indicating saturation. The saturated amine solution will be left to stand, to be separated into two phases after the use of a liquid separator funnel for liquid separation, in which the lower phase is enriched in \(\hbox {CO}_{2}\), known as the \(\hbox {CO}_{2}\)-enriched phase, the upper phase is known as the \(\hbox {CO}_{2}\)-Lean phase. The full text is expressed in terms of of the “\(\hbox {CO}_{2}\)-enriched phase” and “ \(\hbox {CO}_{2}\)-Lean phase”.

Schematic diagram of experimental setup.

The \(\hbox {CO}_{2}\)-enriched phase was utilized for the mineralization experiment after measuring the \(\hbox {CO}_{2}\) concentration in the \(\hbox {CO}_{2}\)-enriched phase using acid titration. Subsequently, \(\hbox {Ca(OH)}_{2}\) was added at a specific molar ratio of Ca/C(0.8, 0.9, 1.0, 1.1, 1.2), followed by dilution to a volume of 500 mL with deionized water. The detailed procedure and calculations for the acid titration method are given in the supporting material.The schematic of the acid-base titration can be found in the supplementary figure in the supporting materials During the experiment, the temperature was controlled within the range of 30–70 \(^{\circ }\)C using a constant temperature magnetic stirrer. At intervals of 5 min during the experiment, 5 mL of the slurry was extracted and filtered through filter paper in a vacuum filtration apparatus. The filter cake was washed with ethanol for three times, and then dried in an oven at 105 \(^{\circ }\)C for 5 h, and last step weighed to calculate its extent of mineralization using Eq. (10). The solid products were analyzed for composition using a thermogravimetric analyzer (TGA), while the filtrate was analyzed for \(\hbox {CO}_{2}\) load using acid titration. The parameters extent of mineralization E6 and \(\hbox {CO}_{2}\) desorption rate39 were defined as Eqs. (10) and (11), respectively. The detailed derivation of the formula (10) is shown in the supporting material.

where \(\bigtriangleup m\) presents the mass of the filter cake at t time \(\textrm{g}\) ; \(\eta _{C\textrm{a}^{2+}}\) denotes the molar concentration of added \(C\textrm{a}^{2+}\) .

where \(\varvec{n}_{\textrm{r}}\) represents the \(\hbox {CO}_{2}\) loading in the saturated \(\hbox {CO}_{2}\)-enriched phase after absorption saturation, and \(\varvec{n}_{\textrm{l}}\) denotes the \(\hbox {CO}_{2}\) loading in the depleted phase after mineralization filtration.

TGA curve of solid products.

We calculate the masses of \(\hbox {CaCO}_{3}\) and \(\hbox {Ca(OH)}_{2}\) in the solid product after mineralization using TGA, and the measurement curve is shown in Fig. 3 Heated from 25 to 895 \(^{\circ }\)C at a rate of 10 \(^{\circ }\)C/min. In the first stage of thermal weight loss shown in the figure, it is attributed to the loss of H\(_{2}\)O resulting from the decomposition of \(\hbox {Ca(OH)}_{2}\). In the second stage, the thermal weight loss is due to the loss of \(\hbox {CO}_{2}\) from the decomposition of \(\hbox {CaCO}_{3}\). To accurately calculate the masses of \(\hbox {Ca(OH)}_{2}\) and \(\hbox {CaCO}_{3}\) in the solid products, the mass at 105 \(^{\circ }\)C is selected as the mass of the solid products (excluding the mass loss due to water evaporation). The formulas for calculating the contents of \(\hbox {Ca(OH)}_{2}\) and \(\hbox {CaCO}_{3}\) in the solid products are provided in Eqs. (12) and (13) respectively.

where 44 is the molecular weight of \(\hbox {CO}_{2}\) and 100.09 is the molecular weight of \(\hbox {CaCO}_{3}\). According to the reaction equation(\(C\textrm{a}CO_3\rightarrow CaO+CO_2\) ) for the decomposition of \(\hbox {CaCO}_{3}\), the mass percentage of \(\hbox {CaCO}_{3}\) in the solid products can be derived from the percentage of \(\hbox {CO}_{2}\) mass lost. Therefore, using the data obtained from TGA in Fig. 3 and applying Eq. (12), the mass percentage of \(\hbox {CaCO}_{3}\) in the solid products can be determined.

where 18 is the molecular weight of H\(_{2}\)O and 74.09 is the molecular weight of \(\hbox {Ca(OH)}_{2}\). According to the reaction equation(\(Ca(OH)_2\rightarrow CaO+H_2O\) ) for the decomposition of \(\hbox {Ca(OH)}_{2}\), the mass percentage of \(\hbox {Ca(OH)}_{2}\) in the solid products can be derived from the percentage of H\(_{2}\)O mass lost. Therefore, using the data obtained from TGA in Fig. 3 and applying Eq. (13), the mass percentage of \(\hbox {Ca(OH)}_{2}\) in the solid products can be determined.

In the circulation experiment, the cycling process is shown in Fig. 4, the \(\hbox {CO}_{2}\)-enriched phase after absorption saturation was separated, the \(\hbox {CO}_{2}\) concentration is determined by acid titration, and the mineralization is carried out after adding \(\hbox {Ca(OH)}_{2}\) according to the optimal Ca/C = 1 determined by the study. The mineralization conditions are set as follows: the temperature is 50 \(^{\circ }\)C, the strring speed is 500 r/min, and the time of mineralization is 120 min. The filtration carried out at the end of the mineralization, and the clarified regenerated phase is obtained to complete the first round of reaction. The regenerated solution after mineralization of the \(\hbox {CO}_{2}\)-enriched phase was mixed with the \(\hbox {CO}_{2}\)-Lean phase after absorption and phase separation in the previous round, and entered into the next cycle to re-absorb, phase separation and mineralization.

Schematic diagram of the circulation principle.

The reaction temperature is a key influencing factor determining the mineralization process, affecting both the extent of mineralization and the \(\hbox {CO}_{2}\) desorption rate, as well as the generation of products. The experiments were conducted under conditions of 30 \(^{\circ }\)C, 40 \(^{\circ }\)C, 50 \(^{\circ }\)C, 60 \(^{\circ }\)C, and 70 \(^{\circ }\)C, with continuous mineralization for 120 min each. As seen from Fig. 5a, with the increase in mineralization temperature, the extent of mineralization gradually increased, reaching a maximum of 97.12% at 70 \(^{\circ }\)C. Thus, overall, increasing temperature promotes the mineralization reaction, although its role in promoting mineralization gradually decreases with rising temperature. Specifically, the growth rate of the extent of mineralization is substantial when the temperature increases from 30 to 50 \(^{\circ }\)C. At 40 \(^{\circ }\)C and 50 \(^{\circ }\)C, the extent of mineralization increased by 48.4% and 65.42% respectively after 120 min. However, when the temperature rises to 60 \(^{\circ }\)C and 70 \(^{\circ }\)C, the growth rates of the extent of mineralization decrease to 9.8% and 1.9% respectively. This indicates that the promoting effect of temperature on mineralization gradually diminishes with higher temperatures. At a mineralization temperature of 30 \(^{\circ }\)C, the rate of increase in mineralization slowed down after 70 min, with a extent of mineralization of only 35.35% after 120 min. When the temperature increased to 40 \(^{\circ }\)C, there was a noticeable improvement in mineralization, reaching 52.46% after 120 min. From 50 to 70 \(^{\circ }\)C, the initial increase in mineralization rate within the first 20 min was significant, followed by a sustained enhancement, resulting in degrees of mineralization of 86.78%, 95.30%, and 97.12% after 120 min, respectively. In the study by Zhang et al.6, a similar extent of mineralization 98.19% was achieved after 100 min of mineralization. Figure 5b shows the variation curves of extend of mineralization and \(\hbox {CO}_{2}\) desorption rate at different temperatures. Both extend of mineralization and \(\hbox {CO}_{2}\) desorption rate increase with increasing temperature.

(a) Variation of extent of mineralization E with time t under different temperature conditions. (b) Variation curves of extent of mineralization and \(\hbox {CO}_{2}\) desorption rate under different temperature conditions.

From the perspective of chemical reaction principles, it can be analyzed that, based on reaction Eq. (9), the main reactants for the generation of mineralization product \(\hbox {CaCO}_{3}\) are \(\hbox {Ca}^{2+}\) and \(CO_{3}^{2-}\) , where the generation of \(CO_{3}^{2-}\) is determined by the dissolution ionization of \(\hbox {Ca(OH)}_{2}\), and the generation of \(CO_{3}^{2-}\) is determined by reaction Eq. (7). Regarding \(CO_{3}^{2-}\), with increasing temperature, the solubility of \(\hbox {Ca(OH)}_{2}\) decreases. At a temperature of 20 \(^{\circ }\)C, its solubility is 1.5305 g/kg of solution. When the temperature rises to 70 \(^{\circ }\)C, its solubility decreases to 1.4225 g/kg of solution. In a 500 mL mineralization system, the influence of temperature on the dissolution of \(\hbox {Ca(OH)}_{2}\) is relatively small. However, the increase in temperature significantly affects the molecular thermal motion, diffusion, and mass transfer rate of \(\hbox {Ca}^{2+}\) in the system, thus promoting the uniformity of the mineralization system and enhancing the extent of mineralization40,41. \(CO_{3}^{2-}\) is derived from the ionization of \(HCO_{3}^{-}\) produced during the \(\hbox {CO}_{2}\) absorption process, which is an endothermic process.

XRD patterns of solid mineralization products under different temperature conditions.

Temperature has a significant impact on the ionization equilibrium constant, and increasing temperature favors the forward process of ionization. Therefore, increasing the temperature promotes the ionization of \(HCO_{3}^{-}\) , resulting in a notable rise in the concentration of \(CO_{3}^{2-}\) within the system. This enhancement favors the carbonation reaction. Moreover, increasing temperature facilitates the diffusion of gaseous \(\hbox {CO}_{2}\) in the solution, thereby promoting the extent of mineralization. For the generation of the mineralization product \(\hbox {CaCO}_{3}\) , on the one hand, the increase in temperature is conducive to reducing the amount of \(\hbox {CaCO}_{3}\) covering the surface of the reactant \(\hbox {Ca(OH)}_{2}\) , so as to improve the conversion rate of the mineralization reaction. And on the other hand, it is conducive to the diffusion of gas-phase \(\hbox {CO}_{2}\) in the solution, which increases the opportunity for contact between \(\hbox {CO}_{2}\) and dissolved \(\hbox {Ca}^{2+}\), thus enhancing the amount of the reaction to generate the mineralization product.However, it is important to note that since the formation of \(\hbox {CaCO}_{3}\) is an exothermic reaction, increasing the temperature has a detrimental effect on its formation. Therefore, as the temperature continues to rise, the promoting effect of temperature on mineralization diminishes. At lower temperatures, increasing the temperature effectively enhances the extent of mineralization with a higher growth rate. However, as the temperature increases further, the growth rate of mineralization degree decreases to 1.9%.

XRD analysis was conducted on the solid products obtained after mineralization, We utilized the JCPDF database in the Jade analysis software for peak identification, and the results are presented in Fig. 6. The \(\hbox {Ca(OH)}_{2}\) peaks at 2\(\theta\) = 18, 35, 50, and 65, as well as the \(\hbox {CaCO}_{3}\) peaks at 2\(\theta\) = 24, 29, 47–48, and 65, are consistent with the experimental findings reported by Zhang et al6. At 40 \(^{\circ }\)C, both calcium carbonate generated from carbonation reaction and unreacted calcium hydroxide were observed. With increasing temperature, the peak responding to calcium hydroxide gradually weakened, approaching disappearance at 70 \(^{\circ }\)C, as observed at peaks 17.18 and 34.10. Meanwhile, as the temperature increased, numerous peaks of calcium carbonate appeared, and the original peaks of calcium carbonate became more prominent, as seen at peaks 28.21 and 85.00. As the temperature rises, the carbonation reaction progresses continuously. After the reaction, the amount of calcium hydroxide in the solid product decreases gradually, while the amount of calcium carbonate increases.

Compared to the traditional thermal regeneration method, which requires heating the temperature above 120 \(^{\circ }\)C to achieve regeneration, the mineralization technique can achieve the extend of mineralization and \(\hbox {CO}_{2}\) desorption rate of over 86.78% and 88.96% at just 50 \(^{\circ }\)C. XRD analysis confirmed that \(\hbox {CO}_{2}\) can be effectively sequestered in \(\hbox {CaCO}_{3}\) products at lower temperatures, avoiding the latent and sensible heat losses caused by high temperatures during thermal regeneration, thereby consuming less energy.

The slow mineralization rate and sluggish reaction kinetics are the primary obstacles to the industrial application of \(\hbox {CO}_{2}\) mineralization42. Reaction kinetics may be limited by three factors. First, the dissolution of \(\hbox {CO}_{2}\) in water; second, the dissolution of \(\hbox {Ca}^{2+}\); and third, the formation process of carbonates. Studies by Wang et al.43 have found that the dissolution of metal bases in minerals, represented in this experiment by the quantity of \(\hbox {Ca(OH)}_{2}\), is a dynamic control step in the carbonation process. Therefore, the influence of the dissolution and molar quantity of \(\hbox {Ca}^{2+}\) in the system on the mineralization process is examined.

From the perspective of the reaction process, the Ca/C molar ratio affects the mineralization process. As shown in Fig. 7, with the increase in Ca/C ratio, the extent of mineralization gradually increases. When Ca/C increases from 0.8 to 1, E increases to 36.66%, 37.67%, and 52.46%, respectively. However, when it continues to increase from 1 to 1.2, E decreases to 40.94% and 41.40%. It can be observed that the extent of mineralization reaches its maximum when Ca/C = 1, while Ca/C ratios greater than or less than 1 weaken the extent of mineralization to some extent.

On one hand, concerning the formation process of \(\hbox {CaCO}_{3}\), initially, \(\hbox {CaCO}_{3}\) aggregates and nucleates to form reaction centers. Then, \(\hbox {Ca}^{2+}\) in the system adsorbs around the reaction centers on the surface of the crystals and diffuses inward6. Increasing the amount of \(\hbox {Ca(OH)}_{2}\) appropriately is beneficial not only for the formation of nuclei44 but also for accelerating the diffusion process, thereby enhancing the rate of \(\hbox {CaCO}_{3}\) formation. On the other hand, when Ca/C is less than 1, increasing Ca/C, that is, increasing the molar quantity of \(\hbox {Ca(OH)}_{2}\), leads to an increase in the concentration of \(\hbox {Ca}^{2+}\) and \(\hbox {OH}^{-}\) dissolved in water, thus promoting the mineralization reaction. However, when Ca/C is greater than 1, increasing the molar quantity of \(\hbox {Ca(OH)}_{2}\) has limited effects on increasing the molar quantity of \(\hbox {OH}^{-}\) in the solution because of the limited solubility. Consequently, increasing \(\hbox {Ca(OH)}_{2}\) further does not lead to additional enhancement of the mineralization extent. On the contrary, when the Ca/C molar ratio exceeds 1, the mineralization product \(\hbox {CaCO}_{3}\) covers the surface of undissolved \(\hbox {Ca(OH)}_{2}\), hindering the leaching and diffusion of \(\hbox {Ca}^{2+}\) in \(\hbox {Ca(OH)}_{2}\) and resulting in a decrease in the final extent of mineralization39. The excess undissolved \(\hbox {Ca(OH)}_{2}\) in the system hinders the solid-liquid-gas mass transfer of the mineralization system24, thereby impeding the mineralization reaction. Therefore, determining the optimal amount of \(\hbox {Ca(OH)}_{2}\) for mineralization is Ca/C = 1.

Variation curve of extent of mineralization under different Ca/C molar ratios.

The quantity of calcium hydroxide not only affects the absorption-coupled mineralization process but also constitutes an important part of the cost. Appropriately increasing the amount of \(\hbox {Ca(OH)}_{2}\) has a positive effect on the mineralization process, facilitating an increase in the extent of mineralization.

As shown in Fig. 7, during the first 30 min of the mineralization reaction, the extent of mineralization and reaction rate when Ca/C > 1 are greater than those when Ca/C = 1. This is because, in the initial stage of the mineralization reaction, the excess \(\hbox {Ca(OH)}_{2}\) dissolved in the solution allows \(\hbox {Ca}^{2+}\), \(\hbox {OH}^{-}\), \(HCO_{3}^{-}\), and \(CO_{3}^{2-}\) to fully contact and react to generate \(\hbox {CaCO}_{3}\), leading to higher degrees of mineralization and reaction rates. Moreover, the increase in Ca/C enhances the quantity of \(\hbox {Ca(OH)}_{2}\). During the initial 30 min, nucleation of \(\hbox {CaCO}_{3}\) predominates in the reaction system44, resulting in an increased amount of \(\hbox {CaCO}_{3}\) generated. As the mineralization progresses, the \(\hbox {CaCO}_{3}\) formed and cover the undissolved \(\hbox {Ca(OH)}_{2}\).39

Figure 8a depicts the TGA curves of mineralization products under different Ca/C molar ratios. The curve responding to Ca/C = 1 exhibits the highest peak in the second stage, indicating the maximum \(m_{co_2}\) according to Eq. (12), and thus, the highest \(\hbox {CaCO}_{3}\) content. Figure 8b illustrates the distribution of \(\hbox {CaCO}_{3}\) and \(\hbox {Ca(OH)}_{2}\) content in mineralization products under different Ca/C molar ratios. At Ca/C = 1, the \(\hbox {CaCO}_{3}\) content accounts for 50.57% of the product, while for other Ca/C conditions, the proportions of \(\hbox {CaCO}_{3}\) content are 43.18%, 43.84%, 35.49%, and 38.16% respectively. Therefore, under the condition of Ca/C = 1, the proportion of \(\hbox {CaCO}_{3}\) in the mineralization product is the highest, consistent with the results in Fig. 7, indicating a more thorough carbonation reaction.

From the analysis above, it is evident that the dispersion of the system has a significant impact on the mineralization process. Figure 9 presents (a) the variation curves of mineralization with and without ultrasonic treatment for 30 min under the mineralization conditions of 50 \(^{\circ }\)C and 500r/min rotation speed, and (b) the variation curves of mineralization with and without ultrasonic treatment for 30 min under the mineralization conditions of 40 \(^{\circ }\)C and 500r/min rotation speed, and (c) the variation curves of mineralization with and without ultrasonic treatment for 30 min under the mineralization conditions of 30 \(^{\circ }\)C and 500r/min rotation speed.

Variation in extent of mineralization before and after ultrasonic treatment under 50 \(^{\circ }\)C, 40 \(^{\circ }\)C and 30 \(^{\circ }\)C conditions.

Under three mineralization temperature conditions, the extent of mineralization in the system is improved after ultrasonic treatment. At 50 \(^{\circ }\)C, the extent of mineralization in the sample group subjected to ultrasonic treatment reaches 95.73%, while the control group achieves 86.78%, indicating a 10.30% increase in extent of mineralization. At a mineralization temperature of 40 \(^{\circ }\)C, the sample group subjected to ultrasonic treatment shows a 20.38% increase in extent of mineralization compared to the control group. Similarly, at a mineralization temperature of 30 \(^{\circ }\)C, the sample group subjected to ultrasonic treatment shows a 28.20% increase in extent of mineralization compared to the control group. SEM analysis of the solid products after mineralization is conducted. As shown in Fig. 10, after ultrasonic treatment, the dispersion and uniformity of the mineralization products are improved, and the aggregation phenomenon of the products is reduced. In contrast, the control group without ultrasonic treatment exhibits significant aggregation.

SEM images before and after ultrasonic treatment under 50 \(^{\circ }\)C mineralization conditions.

(a) TGA changes of mineralization products before and after ultrasonic treatment at 50 \(^{\circ }\)C condition. (b) TGA changes of mineralization products before and after ultrasonic treatment at 40 \(^{\circ }\)C condition. (c) TGA changes of mineralization products before and after ultrasonic treatment at 30 \(^{\circ }\)C condition.

Changes in mass proportion of mineralization products before and after ultrasonic treatment under 50 \(^{\circ }\)C, 40 \(^{\circ }\)C and 30 \(^{\circ }\)C conditions.

In the process of \(\hbox {CO}_{2}\) absorption, as the absorption proceeds the viscosity of the absorbent will gradually become larger, resulting in the movement of \(\hbox {CO}_{2}\) gas molecules in solution is weakened, too late to have a chemical reaction with the amine, so there will be a lot \(\hbox {CO}_{2}\) in the form of bubbles. Through ultrasonic treatment, these bubbles are prone to rupture into smaller bubbles. The shock waves and shear forces generated during this process enhance the activation performance of \(\hbox {Ca(OH)}_{2}\) particles in the system45. Additionally, ultrasonic waves themselves create cavitation bubbles46, which promote the dissolution and movement of Ca ions, thereby enhancing the solid-liquid-gas mass transfer in the system. Ultrasonic radiation also has a thermal effect, increasing the energy within the mineralization system. This results in enhanced thermal motion of \(\hbox {Ca}^{2+}\), facilitating the dissolution of \(\hbox {Ca(OH)}_{2}\) and the uniform diffusion of \(\hbox {Ca}^{2+}\) in the system, which is conducive to the rapid and uniform formation of \(\hbox {CaCO}_{3}\) reaction nuclei47.

Figures 11 and 12respectively show the TGA curves and mass proportion graphs of mineralization products before and after ultrasonic treatment under 50 \(^{\circ }\)C, 40 \(^{\circ }\)C and 30 \(^{\circ }\)C conditions. Under three temperature conditions, the \(m_{co_2}\) in the mineralization products after ultrasonic treatment is greater than that in the mineralization products without ultrasonic treatment. At 50 \(^{\circ }\)C, the mass of \(\hbox {CaCO}_{3}\) in the mineralization products increases from 71% to 78%. At 40 \(^{\circ }\)C, the mass of \(\hbox {CaCO}_{3}\) in the mineralization products increases from 51% to 57% after ultrasonic treatment. At 30 \(^{\circ }\)C, the mass of \(\hbox {CaCO}_{3}\) in the mineralization products increases from 35% to 51% after ultrasonic treatment. These improvements suggest that ultrasonic treatment enhances the mass transfer performance of the mineralization system, strengthens the uniformity and dispersion of the system, and thereby enhances the extent of mineralization.

13C NMR spectra of DEEA and \(\hbox {CO}_{2}\)-lean phase solution.

13C NMR spectra of \(\hbox {CO}_{2}\)-enriched phase and after mineralization.

Figures 13 and 14 present the results of 13C NMR carbon spectrum analysis of the \(\hbox {CO}_{2}\)-lean phase, \(\hbox {CO}_{2}\)-enriched phase, and post-mineralization phase after absorption phase separation. In Fig. 13, the results show that after absorption phase separation, the \(\hbox {CO}_{2}\)-lean phase contains only carbons C1, C2, C3, and C4 from DEEA, indicating the presence of only DEEA and no other substances such as AEP or carbamate in the \(\hbox {CO}_{2}\)-lean phase. In Fig. 14, after the absorption of \(\hbox {CO}_{2}\) and phase separation, the 13C NMR spectrum of the lower phase displays resonances at 164.4 ppm and 162.9 ppm, corresponding to the carbonyl carbon in carbamate and the carbon in bicarbonate/carbonate, respectively. This aligns with the experimental results reported by Hartono et al.48 and Zhou et al.49. Therefore, the rich phase contains carbon atoms from C5, C6, carbonate, and bicarbonate, as well as carbon atoms C9 and C10 from the carboxylate in carbamate. This indicates the presence of both AEP and DEEA, along with the products of carbamate, carbonate, and bicarbonate in the rich phase. The 13C NMR spectra of the regenerated phases show that the peaks of carbon atoms C9 and C10 in carbamate, the carbonate and bicarbonate groups are nearly absent, demonstrating the effective regeneration of the mineralization process.

Using a biphasic absorbent composed of 50wt% DEEA, 25wt% AEP, and 25wt% H\(_{2}\)O, no product peaks were detected in the \(\hbox {CO}_{2}\)-lean phase after \(\hbox {CO}_{2}\) absorption, with all absorption products concentrated in the \(\hbox {CO}_{2}\)-enriched phase. In contrast, in homogeneous absorbents, the absorption products are evenly dispersed throughout the entire absorbent solution. Therefore, the biphasic absorbent effectively concentrates the products into a smaller volume of solution, significantly reducing the amount of solution requiring regeneration. As a result, this reduces the scale and energy demands on mineralization equipment during the cyclic process.

The changes in \(\hbox {CO}_{2}\) loading of the \(\hbox {CO}_{2}\)-enriched phase, \(\hbox {CO}_{2}\) loading of the \(\hbox {CO}_{2}\)-lean phase, \(\hbox {CO}_{2}\) loading of the solution after mineralization, and \(\hbox {CO}_{2}\) desorption rate during 6 cycles of absorption are shown in Fig. 15a. During the cycling process, the loading of \(\hbox {CO}_{2}\)-enriched phase is 11.92 mol/L after 6 cycles from 12.65 mol/L initially, which indicated that the \(\hbox {CO}_{2}\) loading of the \(\hbox {CO}_{2}\)-enriched phase could be maintained at a certain level with the increase of the number of mineralization, and there is a small decrease probably due to the incomplete solid-liquid separation process and the degradation failure of a small amount of amine with the increase of the number of mineralization. But the overall can maintain a better adsorption performance. As the number of cycles increased, the ability of the system to carbonate capacity is also maintained at a certain level, the CO2 desorption rate go from 92.57 to 91.14%.

Figure 15b shows the volume ratio of the \(\hbox {CO}_{2}\)-enriched phase to the \(\hbox {CO}_{2}\)-lean phase during the 6 cycles. The volume ratio of the \(\hbox {CO}_{2}\)-enriched phase remains between 52 and 55%, while the volume ratio of the \(\hbox {CO}_{2}\)-lean phase remains between 45 and 48%, maintaining a good phase separation ratio.Compared to previous studies on biphasic absorbents, such as the work by Xu et al.20, where the DEEA-BDA absorbent achieved a \(\hbox {CO}_{2}\)-enriched phase volume fraction of 78%, Wang et al.50, with a DEEA-DMBA absorbent achieving 85%, Pinto et al.21, with DEEA-MAPA achieving 68%, and Zhang et al.51, with DMCA-TETA achieving 65%, the DEEA-AEP absorbent proposed in this study shows a significantly reduced \(\hbox {CO}_{2}\)-enriched phase volume fraction of 58% after the first absorption and phase separation. Moreover, most existing research primarily focuses on the phase separation performance of biphasic absorbents after the first \(\hbox {CO}_{2}\) absorption, with limited attention to the behavior during multiple absorption-regeneration cycles. Through repeated \(\hbox {CO}_{2}\) absorption, phase separation, mineralization of the \(\hbox {CO}_{2}\)-enriched phase, and cyclic absorption experiments with the mixed solvent, this study found that the DEEA-AEP biphasic absorbent maintains a \(\hbox {CO}_{2}\)-enriched phase volume fraction of only 52–55% during repeated cycles. This effectively keeps the amount of \(\hbox {CO}_{2}\)-enriched solution sent to the mineralization system at a low level throughout multiple cycles, thereby reducing the energy consumption and equipment size required for processing the \(\hbox {CO}_{2}\)-enriched phase during regeneration.

Based on the above discussion, future work should focus on exploring more optimized biphasic absorbent configurations. This includes investigating whether the addition of sterically hindered amines, physical solvents, or other substances can maintain effective cycling while reducing the consumption of organic amines, all while ensuring stable cycling and phase separation.

(a) Changes in the \(\hbox {CO}_{2}\) loading of the \(\hbox {CO}_{2}\)-enriched phase, \(\hbox {CO}_{2}\) loading of the \(\hbox {CO}_{2}\)-lean phase, \(\hbox {CO}_{2}\) loading after mineralization, and \(\hbox {CO}_{2}\) capture efficiency during the cycling process; (b) volume ratio of the \(\hbox {CO}_{2}\)-enriched phase and \(\hbox {CO}_{2}\)-lean phase during the cycling process.

In conclusion, this study investigated the \(\hbox {CO}_{2}\)2 absorption and mineralization process using DEEA-AEP-H\(_{2}\)O solution, demonstrating the feasibility of the technology and the excellent absorption and cycling performance of the absorbent. The mineralization temperature, Ca/C molar ratio, and dispersion of the mineralization system were found to significantly impact the extent of mineralization, \(\hbox {CO}_{2}\) desorption rate, asnd \(\hbox {CaCO}_{3}\) content in the solid product. Higher temperatures (30–70 \(^{\circ }\)C) led to higher extent of mineralization, \(\hbox {CO}_{2}\) desorption rate, and \(\hbox {CaCO}_{3}\) content in the solid product. An optimal extent of mineralization and \(\hbox {CaCO}_{3}\) content in the solid product were achieved at a Ca/C molar ratio of 1.0. Under the conditions of reaction temperatures of 30 \(^{\circ }\)C, 40 \(^{\circ }\)C, 50 \(^{\circ }\)C, and Ca/C = 1, respectively, the mineralization system was ultrasonically treated, and the degree of mineralization was enhanced in all of them. At 50 \(^{\circ }\)C, after 120 min, with Ca/C = 1, the extent of mineralization reached 95.73% after 30 min of ultrasonic treatment. Furthermore, the cyclic experiment of \(\hbox {CO}_{2}\)-enriched phase mineralization after \(\hbox {CO}_{2}\) absorption by DEEA-AEP-H\(_{2}\)O solution was also explored. According to the way of mineralizing the \(\hbox {CO}_{2}\)-enriched phase alone and then mixing the \(\hbox {CO}_{2}\)-Lean phase for cyclic absorption, the stable split-phase performance and cyclic performance of the system can be achieved. After 6 cycles, the \(\hbox {CO}_{2}\)-enriched phase \(\hbox {CO}_{2}\) load decreased from 12.65 mol/L to 11.92 mol/L, and the volume ratio of the \(\hbox {CO}_{2}\)-enriched phase after phase separation was maintained between 52 and 55%.

Compared to traditional thermal desorption regeneration and homogeneous liquids mineralization regeneration, the biphasic absorbent method proposed in this study not only keeps the regeneration temperature below 100 \(^{\circ }\)C, thereby avoiding the high energy consumption associated with thermal regeneration, but also sequesters \(\hbox {CO}_{2}\) directly by transferring it into stable carbonates. Additionally, the phase separation technique concentrates the \(\hbox {CO}_{2}\) absorption product into one phase, reducing the amount of mineralization solution required, and lowering the scale and energy demands of the mineralization equipment, further optimizing the \(\hbox {CO}_{2}\) regeneration process in amine absorbents.

The datasets used and analysed during the current study available from the corresponding author on reasonable request.

Institute, E. Statistical review of world energy (2023).

Hu D, C. X., & Wang X. Research status and prospects on integrated carbon capture and conversion. Sci. Bull. 69, 1012–1024 (2024).

Lv, B., Guo, B., Zhou, Z. & Jing, G. Mechanisms of \(\text{ co}_{2}\) capture into monoethanolamine solution with different \(\text{ co}_{2}\) loading during the absorption/desorption processes. Environ. Sci. Technol. 49, 10728–10735 (2015).

Article ADS PubMed Google Scholar

IEA. \(\text{ Co}_{2}\) emissions in 2023 (2023).

Lee, G., Li, Y. C., Kim, J. Y., Peng, T. & Sargent, E. H. Electrochemical upgrade of \(\text{ co}_{2}\) from amine capture solution. Nat. Energy 1–8 (2020).

Zhang, W., Xu, Y. & Wang, Q. Coupled \(\text{ co}_{2}\) absorption and mineralization with low-concentration monoethanolamine. Energy 241 (2022).

The Administrative Center for China’s Agenda 21, T. U., Global CCS Institute. China carbon dioxide capture, utilization and storage (ccus) annual report (2023) (2023).

Fankhauser, S. et al. The meaning of net zero and how to get it right. Nat. Clim. Change 12 (2022).

Bui, M., Adjiman, C. S., Bardow, A., Anthony, E. J. & Dowell, N. M. Carbon capture and storage (ccs): The way forward. Energy Environ. Sci. 11 (2018).

Liang, Z. et al. Experimental study on the solvent regeneration of a \(\text{ co}_{2}\) -loaded mea solution using single and hybrid solid acid catalysts. AIChE J. 62, 753–765 (2016).

Article ADS Google Scholar

Kim, S., Scholes, C. A., Heath, D. E. & Kentish, S. E. Gas-liquid membrane contactors for carbon dioxide separation: A review. Chem. Eng. J. 411 (2021).

Lin, H., Yang, H., Luo, H., Pei, A. & Fang, M. Research progress on amine absorbent for co2 capture from flue gas. Southern Energy Constr. 6, 8–14 (2019).

Google Scholar

Yan, S., Zhao, S., Wardhaugh, L. & Feron, P. H. M. Innovative use of membrane contactor as condenser for heat recovery in carbon capture. Environ. Sci. Technol. 49, 2532 (2015).

Article ADS PubMed Google Scholar

Gong, D., Zhang, Z.-x. & Zhao, T. Decay on cyclic \(\text{ co}_{2}\) capture performance of calcium-based sorbents derived from wasted precursors in multicycles. Energies (2022).

Macdowell, N. et al. An overview of \(\text{ co}_{2}\) capture technologies. Energy Environ. Sci. 3, 1645–1669 (2010).

Article Google Scholar

Ji, L. et al. Integrated absorption-mineralisation for energy-efficient \(\text{ co}_{2}\) sequestration: Reaction mechanism and feasibility of using fly ash as a feedstock. Chem. Eng. J. 352, 151–162 (2018).

Article Google Scholar

Zhuang, Q., Clements, B., Dai, J. & Carrigan, L. T. years of research on phase separation absorbents for carbon capture: Achievements and next steps. Int. J. Greenhouse Gas Control 52, 449–460 (2016).

Article Google Scholar

Zhuang, Q. & Clements, B. \(\text{ Co}_{2}\) capture by biphasic absorbent-absorption performance and vle characteristics. Energy 147, 169–176 (2018).

Article Google Scholar

Aleixo, M. et al. Physical and chemical properties of dmxtm solvents. In International Conference on Greenhouse Gas Control Technologies (2011).

Xu, Z., Wang, S. & Chen, C. \(\text{ Co}_{2}\) absorption by biphasic solvents: Mixtures of 1,4-butanediamine and 2-(diethylamino)-ethanol. Int. J. Greenhouse Gas Control 16, 107–115 (2013).

Article Google Scholar

Diego et al. Evaluation of a phase change solvent for \(\text{ CO}_{2}\) capture: Absorption and desorption tests. Int. J. Greenhouse Gas Control (2014).

You, J. K., Lee, W. Y., Kim, J. Y., Lee, J. & Hong, Y. K. Screening of biphasic solvents for energy efficient \(\text{ co}_{2}\) capture. Energy Proc. (2017).

Liu, F. et al. Carbon dioxide absorption in aqueous alkanolamine blends for biphasic solvents screening and evaluation. Appl. Energy 233–234, 468–477 (2019).

Article ADS Google Scholar

Wang, R. et al. Superior energy-saving splitter in monoethanolamine-based biphasic solvents for \(\text{ co}_{2}\) capture from coal-fired flue gas. Appl. Energy 242, 302 (2019).

Article ADS Google Scholar

Wang, Y., Song, L. & Ma, K. An integrated absorption-mineralization process for \(\text{ co}_{2}\) capture and sequestration: Reaction mechanism, recycling stability, and energy evaluation. ACS Sustain. Chem. Eng. 9 (2021).

Gislason, S. R. & Oelkers, E. H. Carbon storage in basalt. Science 344, 373–374 (2014).

Article ADS PubMed Google Scholar

Kang, J. M. et al. Energy-efficient chemical regeneration of amp using calcium hydroxide for operating carbon dioxide capture process. Chem. Eng. J. (2018).

Wang, C. et al. Accelerated \(\text{ co}_{2}\) mineralization technology using fly ash as raw material: Recent research advances. Chem. Eng. J. 150676 (2024).

Ji, L. et al. Simultaneous \(\text{ co}_{2}\) absorption, mineralisation and carbonate crystallisation promoted by amines in a single process. J. CO2 Util. 51, 101653 (2021).

Caplow, M. Kinetics of carbamate formation and breakdown. J. Am. Chem. Soc. 90, 6795–6803 (1968).

Article Google Scholar

Lee, S., Song, H.-J., Maken, S. & Park, J.-W. Kinetics of \(\text{ co}_{2}\) absorption in aqueous sodium glycinate solutions. Ind. Eng. Chem. Res. 46, 1578–1583 (2007).

Article Google Scholar

Park, S., Jo, H., Kang, D. & Park, J. A study of \(\text{ co}_{2}\) precipitation method considering an ionic \(\text{ co}_{2}\) and ca (oh)\(_{2}\) slurry. Energy 75, 624–629 (2014).

Article Google Scholar

Kim, S., Shi, H. & Lee, J. Y. \(\text{ Co}_{2}\) absorption mechanism in amine solvents and enhancement of co2 capture capability in blended amine solvent. Int. J. Greenhouse Gas Control 45, 181–188 (2016).

Article Google Scholar

Lingqi M, L. N. Research progress on \(\text{ co}_{2}\) absorption by mixed organic amine solutions. Zhejiang Chem. Ind. 53(10), 40–44 (2022).

Wee, J.-H. A review on carbon dioxide capture and storage technology using coal fly ash. Appl. Energy 106, 143–151 (2013).

Article ADS Google Scholar

Yang, Q. et al. Toward intelligent \(\text{ co}_{2}\) capture solvent design through experimental solvent development and amine synthesis. Energy Fuels 30, 7503–7510 (2016).

Article Google Scholar

Zhang, W., Deng, Z., Wang, Q., Li, J. & Qiu, X. Experimental research on chemical desorption based on \(\text{ co}_{2}\)-rich absorption solutions. Int. J. Greenhouse Gas Control 109, 103356 (2021).

Article Google Scholar

Luo, C. et al. Dbu-based \(\text{ co}_{2}\) absorption-mineralization system: Reaction process, feasibility and process intensification. Chin. J. Chem. Eng. 28, 1145–1155 (2020).

Article Google Scholar

Lu, J. et al. Single-step integrated \(\text{ co}_{2}\) absorption and mineralization using fly ash coupled mixed amine solution: Mineralization performance and reaction kinetics. Energy 286, 129615 (2024).

Article Google Scholar

Olajire, A. A. A review of mineral carbonation technology in sequestration of \(\text{ co}_{2}\). J. Petrol. Sci. Eng. 109, 364–392 (2013).

Article Google Scholar

Lin, X. et al. A review on carbon storage via mineral carbonation: Bibliometric analysis, research advances, challenge, and perspectives. Sep. Purif. Technol. 126558 (2024).

Wang, F., Dreisinger, D., Jarvis, M., Hitchins, T. & Dyson, D. Quantifying kinetics of mineralization of carbon dioxide by olivine under moderate conditions. Chem. Eng. J. 360, 452–463 (2019).

Article Google Scholar

Feng, B., Yong, A. K. & An, H. Effect of various factors on the particle size of calcium carbonate formed in a precipitation process. Mater. Sci. Eng. A 445, 170–179 (2007).

Article Google Scholar

Nguyen, T. T., Tsai, C. K. & Horng, J. J. Sustainable recovery of valuable nanoporous materials from high-chlorine mswi fly ash by ultrasound with organic acids. Molecules (Basel, Switzerland)27 (2022).

Sonawane, S. H. et al. An innovative method for effective micro-mixing of \(\text{ co}_{2}\) gas during synthesis of nano-calcite crystal using sonochemical carbonisation. Chem. Eng. J. 143, 308–313 (2008).

Article Google Scholar

Chen, J. et al. Study on the accelerated carbonation of mswi fly ash under ultrasonic excitation: \(\text{ Co}_{2}\) capture, heavy metals solidification, mechanism and geochemical modelling. Chem. Eng. J. (2022).

Chen, J. et al. Study on the accelerated carbonation of mswi fly ash under ultrasonic excitation: Co2 capture, heavy metals solidification, mechanism and geochemical modelling. Chem. Eng. J. (2022).

Wang, R. et al. Energy-saving co2 capture using sulfolane-regulated biphasic solvent. Energy 211, 118667 (2020).

Article Google Scholar

Zhou, X., Liu, F., Lv, B., Zhou, Z. & Jing, G. Evaluation of the novel biphasic solvents for co2 capture: Performance and mechanism. Int. J. Greenhouse Gas Control 60, 120–128 (2017).

Article Google Scholar

Wang, L., An, S., Li, Q., Yu, S. & Wu, S. Phase change behavior and kinetics of \(\text{ co}_{2}\) absorption into dmba/deea solution in a wetted-wall column. Chem. Eng. J. 314, 681–687 (2017).

Article ADS Google Scholar

Zhang, S., Shen, Y., Shao, P., Chen, J. & Wang, L. Kinetics, thermodynamics, and mechanism of a novel biphasic solvent for \(\text{ co}_{2}\) capture from flue gas. Environ. Sci. Technol. 52, 3660–3668 (2018).

Article ADS PubMed Google Scholar

Download references

The research was sponsored by the Guizhou University Talent Introduction Research Program (Guizhou University Doctoral Fund [grant (2022) 72]) and the Guizhou Province Science and Technology Support Program (QIANKEHE Support General 018).

Electrical Engineering College, Guizhou University, Guiyang, 550025, China

Qian Wang, Dehong Gong, Jiangdong Zhu & Qingling Luo

School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China

Zhongxiao Zhang

You can also search for this author in PubMed Google Scholar

Qian Wang wrote the main manuscript text. Dehong gong and Zhongxiao Zhang provided guidance on the article. Jiangdong Zhu and Qingling Luo prepared all figures.

Correspondence to Dehong Gong.

The authors declare no competing interests.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Reprints and permissions

Wang, Q., Gong, D., Zhang, Z. et al. Experimental study on the cyclic mineralization of CO2 enriched phase after absorption by a novel biphasic absorbent composed of DEEA and AEP. Sci Rep 14, 26759 (2024). https://doi.org/10.1038/s41598-024-78097-9

Download citation

Received: 11 July 2024

Accepted: 28 October 2024

Published: 05 November 2024

DOI: https://doi.org/10.1038/s41598-024-78097-9

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

News

Experimental study on the cyclic mineralization of CO2 enriched phase after absorption by a novel biphasic absorbent composed of DEEA and AEP | Scientific Reports