CO2 Stripping Research Articles

High‐frequency (470 kHz) ultrasonics‐assisted room temperature CO2 stripping and fate of Sono exposed solvent

AbstractBACKGROUNDThe conventional CO2 stripping process in solvent‐based postcombustion CO2 capture (PCCC) process uses heating to strip the CO2 (~120 °C). However, the challenges associated with this method are high energy consumption in degassing the CO2 from solvent, solvent loss and degradation resulting from the high –temperatures, resulting in high energy consumption typical of solvent‐based PCCC. The present study demonstrates the use of bath‐type sonication (470 kHz frequency) to remove CO2 from CO2 loaded 30 wt% Monoethanolamine under controlled temperature conditions. Solvent performance was evaluated following exposure to 2 h conventional heating and 75 h sonication.RESULTSIn a batch sono‐assisted process, CO2 stripping became possible at 17.5 °C compared to 102.2 °C using the conventional method. Increasing the sonication time led decreased carbon loading and increased stripping efficiency. The stripping rate was high at the initial stages of treatment. Evaluation of sono‐exposed solvents exhibited decreased pH during CO2 loading and decreased absorption capacity of the conventionally heated sample.CONCLUSIONThe sono‐assisted method consumes 3.57‐foldless energy than conventional heating. Its CO2 stripping rate was found to be higher within 5 min of sonication. Notably, the maximum temperature reached for the 1 h intervening mode of sonication at 470 kHz was 49.49 °C. The reduction in absorption capacity per hour of conventional heating was 24.5%, whereas for sonication it was <0.4% and solvent loss was 19.7% lower than conventional. There was no significant change in the color, pH and density of the sample. A 20.4% higher surface tension than that of the virgin sample was observed. © 2024 Society of Chemical Industry (SCI).

Carbon dioxide stripping from acidic wastewater through a vortex venturi tubular microbubble generator

Microbubble generation technology can improve CO2 stripping efficiency while consuming less sweeping gas. In this paper, a vortex venturi tubular microbubble generator is developed based on the concept of “Initial bubble generation with a thin plate type static mixing element” and “Bubble collapse with a venturi channel”. Microbubble characteristics were tested, followed by post-processing of the focused beam reflectance measurement (FBRM) to obtain a multidimensional dataset. The test results indicated that the microbubble quality generated by the vortex venturi tubular microbubble generator was higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the average bubble diameter was 107.05 μm, and microbubbles accounted for 93.29 %. The average bubble diameter of the SV-type static mixer was 473.55 μm, and the proportion of microbubbles was 23.81 % under identical conditions. Furthermore, the CO2 removal efficiency and pH enhancement rate were greatly affected by the gas-liquid volume ratio and the inlet water flow rate, and both fitted an exponential equation correlation. Accordingly, when the gas-liquid volume ratio increased, the quantity of bubbles generated significantly influenced the CO2 stripping efficiency. The stripping efficiency based on the tubular microbubble generator is significantly higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the CO2 removal efficiency was equivalent to that of the SV-type static mixer at a gas-liquid volume ratio of 3.5. When achieving equal CO2 removal efficiency, the gaseous nitrogen consumption of the tubular microbubble generator was 48.61 %-63.30 % lower than that of the SV-type static mixer, and the corresponding energy consumption of the gas compressor was reduced by 38.24 %-55.83 %. The CO2 stripping process based on the vortex venturi tubular microbubble generator offers an environmentally and economically viable treatment option for acid wastewater.

A process to utilize lithium and magnesium resources from low-magnesium salt lake brine through extraction and CO2 stripping

The lithium resources in Tibet's salt lake account for more than 31 % of China's total, featuring a low magnesium-to-lithium ratio with its carbonate-type salt lakes representing a unique resource of the region. When extracting lithium from low-magnesium salt lakes (carbonate-type salt lakes) using a β-diketone system, it is common practice to add alkaline reagents at the front end to precipitate and remove magnesium. This study utilizes the LIX54/TRPO-ADD-1 system for the co-extraction of lithium and magnesium from the brine of the Jiezechaka salt lake, employing CO2 for stepwise stripping to separate lithium and magnesium, using a weak acid instead of a strong acid for stripping to avoid impacting Tibet's fragile ecological environment. By controlling the pH with varying amounts of CO2, an extraction efficiency of 92.54 % for lithium at pH=8.5 and an A/O = 1:5, and complete stripping of magnesium from the loaded organic phase at pH=7 with an A/O = 1:3.2 over three theoretical stages was achieved. This new process omits the front-end magnesium precipitation step, offering a new avenue for the separation of lithium and magnesium in salt lakes and the resource utilization of magnesium.

Modeling and uncertainty quantification of CO2 absorption process using phase separation solvent

Absorption using an amine solvent is one of the primary means for capturing CO2 from many combustion sources such as fossil fuel power plants. CO2 capture systems by absorption need a large amount of thermal energy to strip CO2 from the amine solvent. In recent years, absorption using a phase separation solvent, which forms two phases when CO2 is absorbed, has been demonstrated as a promising technique to reduce the energy consumption. In this study, we examine several process models for the CO2 absorption process using a phase separation solvent, and quantify the uncertainty of the model parameters. We estimated model parameters, including equilibrium and mass transfer parameters, from two sources of experimental data: solubility tests, as well as lab-scale absorber tests. Model parameters were estimated by Bayesian inference using the Markov chain Monte Carlo method. The proposed approach successfully quantified the uncertainties of the model parameters.

Intensification of the CO2-capturing methanol steam reforming process: A comprehensive analysis of energy, economic and environmental impacts

The methanol (MeOH) steam reforming (MSR) process plays an important role in the MeOH-based international renewable energy supply chain. To address the challenges related to the high cost and substantial CO2 emissions linked to the state-of-the-art integrated MSR process, this study aims to propose and enhance an intensified MSR process focusing on energy utilization, economic viability and environmental impact. Aside from the MSR process, the overall scenario also includes the water–gas-shift reaction (WGS) process, CO2 capture using amine-based methods, liquefaction, and hydrogen purification through pressure-swing adsorption. Based on this study, apparent enhancements of the state-of-the-art MSR process can be achieved by adjusting key process variables, especially those related to the CO2 capture process, and by incorporating various intensification strategies, including heat integration (with feed-effluent heat exchangers) between the MSR and the WGS processes, implementing a side-draw intercooling structure of the CO2 absorber, splitting the rich solvent flow to the CO2 stripper, and employing a multi-stage CO2 stripper with vapor recompression. Compared to the state-of-the-art MSR process in the literature, the intensified MSR process produces ultra-pure hydrogen (99.99 mol%) as a main product while reduces 6.2 % of the shared cost (from 191.0 USD/t-MeOH to 179.1 USD/t-MeOH), increases the overall carbon capture rate by 3 % (from 86.73 % to 89.99 %), and reduces the direct CO2 emission by approximately 25 % (from 1.41 t-CO2/ t-MeOH to 1.06 t-CO2/ t-MeOH). Within a MeOH-based international renewable energy supply chain, these enhancements can also significantly lower the imported cost of electricity from 105.9 USD/MWh to 95.5 USD/MWh.

Validation of a CFD model for cell culture bioreactors at large scale and its application in scale-up

Among all the operating parameters that control the cell culture environment inside bioreactors, appropriate mixing and aeration are crucial to ensure sufficient oxygen supply, homogeneous mixing, and CO2 stripping. A model-based manufacturing facility fit approach was applied to define agitation and bottom air flow rates during the process scale-up from laboratory to manufacturing, of which computational fluid dynamics (CFD) was the core modeling tool. The realizable k-ε turbulent dispersed Eulerian gas-liquid flow model was established and validated using experimental values for the volumetric oxygen transfer coefficient (kLa). Model validation defined the process operating parameter ranges for application of the model, identified mixing issues (e.g., impeller flooding, dissolved oxygen gradients, etc.) and the impact of antifoam on kLa. Using the CFD simulation results as inputs to the models for oxygen demand, gas entrance velocity, and CO2 stripping aided in the design of the agitation and bottom air flow rates needed to meet cellular oxygen demand, control CO2 levels, mitigate risks for cell damage due to shear, foaming, as well as fire hazards due to high O2 levels in the bioreactor gas outlet. The recommended operating conditions led to the completion of five manufacturing runs with a 100% success rate. This model-based approach achieved a seamless scale-up and reduced the required number of at-scale development batches, resulting in cost and time savings of a cell culture commercialization process.

Continuous biomethanation of flue gas-carbon dioxide using bio-integrated carbon capture and utilization

Biomethanation of carbon dioxide (CO2) from flue gas is a potential enabler of the green transition, particularly when integrated with the power-to-gas chain. However, challenges arise in achieving synthetic natural gas quality when utilizing CO2 from diluted carbon sources, and the high costs of CO2 separation using amine-based solutions make large-scale implementation unfeasible. We propose an innovative continuous biomethanation system that integrates carbon capture and CO2 stripping through microbial utilization, eliminating expenses with the stripper. Stable continuous biomethane production (83–92 % methane purity) was achieved from flue gas-CO2 using a biocompatible aqueous n-methyldiethanolamine (MDEA) solution (50 mmol/L) under mesophilic and hydrogen-limiting conditions. MDEA was found to be recalcitrant to biodegradation and could be reused after regeneration. Demonstrating the microbial ability to simultaneously strip and convert the captured CO2 and regenerate MDEA provides a new pathway for valorization of flue gas CO2.

Composite nanofibrous membranes with two-dimensional ZIF-L and PVDF-HFP for CO2 separation

Membrane gas-solvent contactors show effective CO2 capture as compared to solvent absorption. However, the overall efficiency of the capture process is compromised by the relatively low CO2 transfer rate of existing commercial membranes. Herein, we propose the integration of a two-dimensional zeolitic imidazolate framework (ZIF-L) with outstanding CO2 adsorption properties into porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibre membranes for energy-efficient CO2 separation through membrane gas absorption. Well-defined composite structures of the nanofibre membranes with ZIF-L are fabricated using the electrospinning technique. The favourable adsorption of CO2 molecules in the unique cushion-shaped cavities of ZIF-L enhances CO2 flux during both absorption and stripping processes even under mild temperature conditions when utilised in the composite nanofibre membranes. Consequently, the PVDF-HFP membrane with 5 wt% ZIF-L presents 26.7 mmol m−2 s−1 of CO2 stripping flux at 100 °C.

Molecular Simulation of Thermodynamic Properties of CH4/CO2 Adsorption by Coal Molecules at Different Temperatures and Moisture Contents under Variable Pressure Conditions.

In order to further elucidate the thermodynamic mechanism of CH4/CO2 adsorption by coal molecules, the adsorption behavior of a molecular model of coal (C206H128O36N2) at Wucaiwan, Zhundong was investigated by applying Materials Studio 2020 and Monte Carlo (GCMC) simulation methods, and the adsorption behavior of CH4 and CO2 was studied from the thermodynamic point of view under the conditions of different temperatures, pressures, and moisture contents. The results showed that at different temperatures or moisture contents, CH4 molecules had a low-density scattering distribution and CO2 molecules had a high-density polymerization distribution. Temperature and moisture content and adsorption constants a and b were negatively correlated. Under the same conditions, the relationship between single- and binary-component adsorption amounts was CO2 > CH4 and the relationship between heat of adsorption was CO2 > CH4. When adsorption potential energy or entropy of adsorption was the same, the adsorption capacity was CO2 > CH4. Temperatures and moisture contents were negatively correlated with the total adsorption capacity of CH4/CO2; pressure was positively correlated with the total adsorption capacity of CH4/CO2. The effect of temperature on the equivalent heat of adsorption was greater than that of pressure at different temperatures, and the entropy of adsorption was positively correlated between temperature and CH4/CO2, while the amount of adsorption was negatively correlated with the entropy of adsorption. The effect of moisture content on the equivalent heat of adsorption was greater than that of pressure at different moisture contents, and the entropy of adsorption was negatively correlated between moisture content and amount of adsorption. The adsorption entropy of CH4/CO2 was negatively correlated, and the adsorption amount was positively correlated to the adsorption entropy. At a temperature above 318 K or moisture content above 10%, the total CH4/CO2 adsorption decreased significantly and the CO2 adsorption decreased significantly. From a thermodynamic point of view, the presence of a large amount of H2O had a much greater effect on CO2 than on CH4, and an increase in temperature or moisture content was unfavorable for CO2 sequestration, CO2 stripping of CH4, and control of CH4 diffusion and desorption, whereas at low temperature, high pressure, and moisture content <1%, the effect of stripping, sequestration, and control was good.

Ammonia stripping and scrubbing followed by nitrification and denitrification saves costs for manure treatment based on a calibrated model approach

Resource-efficient nitrogen management is of high environmental and economic interest, and manure represents the major nutrient flow in livestock-intensive regions. Ammonia stripping/scrubbing (SS) is an appealing nitrogen recovery route from manure, yet its real-life implementation has been limited thus far. In nutrient surplus regions like Flanders, treatment of the liquid fraction (LF) of (co–)digested manure typically consists of nitrification/denitrification (NDN) removing most N as nitrogen gas. Integrating SS before NDN in existing plants would expand treatment capacity and recover N while maintaining low N effluent values, yet cost estimations of this novel approach after process optimisation are not yet available. A programming model was developed and calibrated to minimise the treatment costs of this approach and find the balance between N recovery versus N removal. Four crucial operational parameters (CO2 stripping time, NH3 stripping time, temperature and NaOH addition) were optimised for 18 scenarios which were different in terms of technical set-up, influent characteristics and scrubber acid. The model shows that SS before NDN can decrease the costs by 1 to 56% under optimal conditions compared to treatment with NDN only, with 1 to 8% reduction for the LF of manure (22–29% recovered of N treated), and 11 to 56% reduction for the LF of co-digested manure (42–67% recovered of N treated), primarily dependent on resource pricing. This study shows the power of modelling for minimum-cost design and operation of manure treatment yielding savings while producing useful N recovery products with SS followed by NDN.

Ultra-low temperature sono-assisted CO2 stripping/ carbon-rich solvent regeneration using different ultrasonic frequencies

ABSTRACT Carbon dioxide emission from anthropogenic sources plays a major role in global warming and climate change. Conventional amine-based carbon capture is matured technology that has limitations on high-temperature use imposed by solvent degradation and solvent loss during CO2 stripping/regenerating solvent. The present experimental investigation involves the application of tank-type (bath-type) sonication for CO2 stripping from aqueous carbon-rich 30 wt% MEA solvent in a low temperature-controlled environment, using ultrasonic frequencies of 25 kHz (cavitation-dominant), 360 kHz (streaming-dominant), and 58/132 kHz dual-mode (combined phenomena). The results are analyzed to understand the effects of carbon loading, CO2 stripping efficiency, stripping rate, temperature profile, and energy demand. The stripping rate is higher in the low-temperature range of 6°C to 12°C for all the frequencies due to the sonication effect. In the mid setpoint range of 15°C to 30°C, the CO2 stripping rate is lower due to the combination of sonication and temperature effect, and when the temperatures increase from 40°C to 45°C, the stripping rate increases gradually due to additional temperature effect. A high cyclic capacity of 1.12 mol CO2/kg. was observed for 360 kHz frequency at 12°C. The lowest energy of 3.94 kJ/mol CO2 was achieved for 360 kHz at a setpoint of 12°C. Factors such as sonication frequency, CO2 loading (mol CO2/mol soln.), temperature, and nominal power of ultrasonics play an important role in determining the sensible energy required for CO2 stripping. Specifically, CO2 stripping at the low temperature set point of 6°C and 12°C is found to be promising in all frequencies, indicating that CO2 stripping is primarily promoted by sonication, rather than by temperature.

Application of electrically conductive membrane contactor in the carbon dioxide stripping process for mitigation of fouling induced by flue gas

Carbon capture utilization & storage (CCUS) process is a promising technology for reducing greenhouse gas emissions. However, the biggest challenge in commercializing CCUS is reducing energy consumption during the CO2 stripping stage. Membrane contactors have been developed to reduce energy consumption and improve CO2 stripping performance. However, traditional polymer-based membranes are vulnerable to damage by combustion residues such as oil and grease. To address this problem, electrically conductive membranes (ECMs) have been developed to enable efficient electrochemical reactions for anti-fouling purposes. This study investigated the anti-fouling performance of an electrically conductive membrane contactor (ECMC) for CO2 stripping. Surface modification with a two-layered ECM resulted in the superior electrical conductivity and CO2 stripping flux compared to other ECMs. Electrostatic repulsion effectively mitigated fouling by 92.1 % compared to non-charged ECMC by preventing the attachment of oil and grease, but it was not observed a significant effect in high oil and grease concentrations. The electrochemical oxidation process when applying a high voltage improved anti-fouling performance, and the O2 sweep gas mode greatly maintained the CO2 stripping flux at 95.2 % with high oil and grease concentrations. Furthermore, the feasibility of the ECMC was demonstrated by comparing the predicted total energy consumption per CO2 amount under actual operating conditions. In conclusion, ECMC improved the energy efficiency of CO2 stripping by providing high anti-fouling performance in CCUS.

Process design and energy assessment of an onboard carbon capture system with boilers or heat pumps for additional steam generation

ABSTRACT This study proposes a novel onboard carbon capture system (OCCS) with reduced fuel consumption. The proposed system included a heat pump with an intermediate heat exchanger, a parallel compressor, and a steam compressor. The proposed system consumed 43% less fuel than the boiler for producing the same amount of steam, which was required for CO2 stripping. In addition, a blended solvent of amino methyl propanol (AMP) and piperazine (PZ) was applied to the OCCS. A rate-based process simulation indicated that this solvent resulted in 22% lower reboiler duty, compared to a monoethanolamine (MEA) solvent. Further, it was shown that the proposed OCCS with the heat pump and the AMP/PZ solvent achieved a reduction of approximately 50% in both fuel consumption and CO2 emissions along with 26.9 USD reduction for capturing one ton of CO2, compared to the OCCS with a boiler and MEA solvent.

High performance CO2 Absorption/Desorption using Amine-Functionalized magnetic nanoparticles

In the current study, for the first time, a variety of amino acid groups, including arginine, histidine, and glycine, were added to Fe3O4 nanoparticles to achieve desired mass and heat transfer properties in CO2 absorption/desorption experiments. For this purpose, different concentrations of synthesized nanoparticles were employed in base fluid (10 wt% methyldiethanolamine) in a semi batch experiment at ambient pressure for CO2 absorption and desorption. The experimental results clearly indicated that modification of iron oxide nanoparticles could enhance CO2 absorption and stripping significantly, as a result of higher stability of nanoparticles and presence of amino groups at the nanoparticles' structure. Compared to bare Fe3O4, Fe3O4@arginine, Fe3O4@histidine, and Fe3O4@glycine demonstrated 23%, 17%, and 10% increase in CO2 absorption capacity, respectively. By using chemical agent as stabilizer species and by modified thermal properties of solution, magnetic nanoparticles promoted CO2 desorption to a great extent. Therefore, Fe3O4@arginine, Fe3O4@histidine, and Fe3O4@glycine nanofluids improved CO2 desorption enhancement by 48.2%, 47.2%, and 46.1% at 70 °C, respectively.

An intensified low-energy ultrasonic plug reactor for CO2 desorption from single and novel blended absorbents

Ultrasound as an efficient emerging technology for CO2 desorption enhancement has attracted great attention in recent years. In the present study, a mini-plug reactor was equipped with a 28 kHz ultrasound transducer and employed for CO2 stripping from different amine-based solutions. First, 30 wt% aqueous solutions of MEA, DEA, DIPA and MDEA were investigated under the effect of desorption temperature and flow rate of the solution. 26.4% energy saving and around 70% enhancement in desorption was reached for MEA at 55℃ using ultrasound irradiation. Some novel tri-solvent blends were also studied in the optimum temperature. Among four blended amine solutions, new aqueous solution of MEA+DIPA+AMP showed the maximum desorption rate of 84.2% and minimum regeneration energy of 2.7 MJ/kgCO2 using the designed ultrasound-equipped plug reactor. It was concluded that CO2 desorption from the MEA+DIPA+AMP blend could reduce required energy consumption by around 35% compared to 30 wt% MEA using conventional method. The present study provided an efficient intensified desorber as well as a kind of tri-solvent blend as a brilliant system for CO2 capture process at lower temperature than conventional.

Steady-state and dynamic model for recirculating aquaculture systems with pH included

In this work, simplified steady-state and dynamic models of a Recirculating Aquaculture System (RAS) of Atlantic salmon (Salmo salar) are described. The RAS process under study includes a fish tank, a biofilter, a CO2 stripper, and an oxygen cone. Compared to existing models, the main contribution is that it explicitly models the pH, by using reaction invariants such as total inorganic carbon (TIC), total ammonia nitrogen (TAN), and alkalinity. As the possibility of placing the pH/alkalinity adjustment (base or buffer addition) into the fish tank or into the biofilter was considered, four steady-state scenarios were studied, where one of the adjustments is utilized in each scenario. A dynamic simulation of the process with oxygen and pH controllers was performed and compared with commercial RAS production data, and what adjustments had to be done to get an agreement between the model and the plant data.

A facile synthesized robust catalyst for efficient regeneration of biphasic solvent in CO2 capture: characterization, performance, and mechanism

Amine-based technology is promising for CO2 capture from the flue gas. However, it encounters high energy penalty and thus hampers its industrial application. Currently, the catalytic solvent regeneration is developing to lower down regeneration temperature, accelerate regeneration rate, and cut down energy consumption for monoethanolamine (MEA)-based process. However, the information on catalytic regeneration of biphasic solvent is seldom available. This work develops a facile synthesized robust catalyst, α-Fe2O3, to promote the biphasic solvent regeneration such as triethylenetetramine (TETA) and 2-(diethylamino) ethanol (DEEA) blend. Experimental results revealed that, with the aid of α-Fe2O3, the efficient regeneration of TETA-DEEA occurred at 94 °C, which is far below the conventional MEA-based process (110–120 °C). The corresponding CO2 stripping rate increased by 2.4 times compared with uncatalytic scenario. Furthermore, the relative energy consumption was furtherly decreased by 41.6%. Different from MEA regeneration, the biphasic solvent regeneration with α-Fe2O3 depended on the enhancement of water molecules proton donation rather than the abundant Brønsted acid and Lewis acid of the catalyst. Based on DFT calculation and 13C NMR spectra analysis, the water molecules on α-Fe2O3 surface and the protonated DEEA were parallel served as proton donors for carbamate decomposition. Consequently, a novel proton transfer mechanism was proposed for the biphasic solvent TETA-DEEA regeneration. The water molecules adsorbed on α-Fe2O3 surface generated oxyhydrogen groups and thus donate protons for the carbamate decomposition. This work proposes a novel proton transfer mechanism for solvent regeneration and advances its industrial application with a low energy penalty.

Enhanced CO2 absorption and reduced regeneration energy consumption using modified magnetic NPs

This study aimed to investigate the ability of nanofluids in improving CO2 absorption and reducing regeneration energy demand in a bubble column reactor in the presence of functionalized-magnetic NPs. The first step was to synthesize Fe3O4 nanoparticles (NPs), which were then functionalized with Aspartic-acid and Lysine. Next, to study CO2 absorption and stripping performances, the NPs with different concentrations were dispersed in an aqueous methyl diethanol amine (MDEA) solution (10 wt%). The investigation of CO2 absorption performance, CO2 loading and pH of all nanofluids were reported at different times of absorption experiments. The obtained results indicated that Fe3O4@Aspartic (Fe3O4@Asp) and Fe3O4@Lysine (Fe3O4@Lys) NPs improved CO2 loading up to 15.3% and 21.4%, respectively, as compared to Fe3O4 NPs. In addition, the functionalized-magnetic NPs showed more positive effects on CO2 desorption compared to bare Fe3O4. To show regeneration efficiency, the outlet gas flow rate and its CO2 concentration were measured and the CO2 loading and pH were determined at the end of the desorption experiment. The results revealed that at 70 °C, the CO2 loading was reduced by 58.9% and 55.1% applying Fe3O4@Lys and Fe3O4@Asp, respectively. Therefore, more energy could be saved in desorption process using functionalized magnetic NPs.

Intensification of Sono-Assisted CO2 Stripping/Carbon-Rich Solvent Regeneration by Fe2O3 Hydrophobic Micronized Particles

In 2020, the amount of CO2 generated by coal combustion was estimated to be 15.32 Gt CO2. In a solvent-based postcombustion CO2 capture (PCCC) process, the solvent regeneration/CO2 stripping process uses thermal energy to regenerate the solvent. It has an adverse impact on the solvent’s thermal stability, besides causing a significant quantity of solvent loss and a high energy demand. In recent times, one method for PCCC cost savings has emerged: sono-assisted solvent regeneration/CO2 stripping. The present work focuses on enhancing the high-frequency ultrasound-assisted aqueous carbon-rich 30 wt % monoethanolamine (MEA) solvent regeneration/CO2 stripping process using Fe2O3 hydrophobic micronized particles (concentrations varied in the ranges of 0.005, 0.01, 0.05, 0.1, and 0.2 wt %) in a controlled-temperature environment at 12 °C using 360 kHz, 470 kHz, and 1 MHz (streaming-dominant frequencies). From the investigation, the lowest concentration (0.005 wt %) of micronized particles shows maximum enhancements of 12.29, 20.93, and 33.62%, thereby decreasing the solvent sensible energy requirements by 1.26, 2.4, and 2.9 times than without micronized particles for the tested frequencies. In addition, the observed CO2 stripping rate is much higher when compared to the case without micronized particles. The stripping efficiency is observed to be high in the initial stages of sonication (5 min).

Evaluation of CO2 absorption and stripping process for primary and secondary amines

ABSTRACT An effective approach for lowering CO2 emissions from industrial processes is the absorption method of CO2 capture. Because of the high energy required to break the bond of the carbamate ions during the stripping process, the intramolecular interaction (repulsive interaction) of Ncarbamate-Ccarbamate was discovered to be the main interaction. Therefore, the purpose of this study is to examine the amine-CO2 bond strength for various carbamate molecules during the regeneration process using molecular dynamic modelling, as well as to explore the diffusion coefficient of various amines. The results of interaction intensity show that in comparison to other studied amines for inter – and intra-molecular interactions N, N, N′, N′-tetramethylpropane-1,3-diamine (TMPAD), N-dimethylcyclohexanamine (DMCA) and 4-diethylamino-2-butanol (DEAB) were easy to break. It shows that the TMPAD has the highest repulsive interaction; consequently, it needs the lowest energy to break the carbamate ion in the stripping process as compared to MEA. The order of regeneration energy required to break the bond for Ncarbamate-Ccarbamate in various selected amines from higher to lower is MEA > 2MAE > PZ > 2DMAE > 2EAE > AMP > 1DMA2P > MCA > DMCA > DEAB > TMPAD. The diffusion coefficient data for various blends reveal that the 2MAE-DEAB blend has the highest rate of diffusion when compared to other blends (2MAE-1DMA2P and 2MAE-TMPAD).