| 1. |
- Anbalagan, Anbarasan, et al.
(författare)
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Continuous photosynthetic abatement of CO2 and volatile organic compounds from exhaust gas coupled to wastewater treatment : Evaluation of tubular algal-bacterial photobioreactor
- 2017
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Ingår i: Journal of CO2 Utilization. - : Elsevier Ltd. - 2212-9820 .- 2212-9839. ; 21, s. 353-359
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Tidskriftsartikel (refereegranskat)abstract
- The continuous abatement of CO2 and toluene from the exhaust gas by an indigenous microalgal-bacterial consortium was investigated in a pilot tubular photobioreactor interconnected to an absorption column using diluted centrate in seawater as a free nutrient source. The removal efficiency of CO2 and toluene was maximised in the vertical absorption column by identifying an optimum liquid to gas (L/G) ratio of 15. The photobioreactor supported steady-state nitrogen and phosphorus removals of 91 ± 2% and 95 ± 4% using 15% diluted centrate at 14 and 7 d of hydraulic retention time (HRT), respectively. A decrease in the removal efficiencies of nitrogen (36 ± 5%) and phosphorus (58 ± 10%) was recorded when using 30% diluted centrate at 7 d of HRT. The volumetric biomass productivities obtained at an HRT of 7 d accounted for 42 ± 11 and 80 ± 3 mg TSS L-1 d-1 using 15 and 30% centrate, respectively. Stable CO2 (76 ± 7%) and toluene removals (89 ± 5%) were achieved at an L/G ratio of 15 regardless of the HRT or centrate dilution. Hence, this study demonstrated the potential of algal-bacterial systems for the continuous removal of CO2 and volatile organic compounds from exhaust gas coupled with the simultaneous treatment of centrate.
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| 2. |
- Chavez-Caiza, J., et al.
(författare)
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Unveiling the effect of sacrificial agent amount in the CO2 photoreduction performed in a flow reactor
- 2024
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Ingår i: Journal of CO2 Utilization. - : Elsevier BV. - 2212-9820 .- 2212-9839. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- The use of sacrificial agents in photocatalysis is a powerful resource to enhance the performance of photoactive materials. Despite its importance, the effect of the amount of sacrificial agent is not properly described in the literature. In this paper, we have focused on the role of EtOH in the photoreduction of CO2 to CH4 using Cu-P25 photocatalysts in a flow reactor. We found that the production of CH4 increased with the concentration of EtOH, achieving an outstanding CH4 production yield of 235 mu mol/(g & sdot;h) for a flow of 0.25 mu mol/min of EtOH in the gas stream, hinting at the important role of the sacrificial agent in the reaction. The catalytic results together with the characterization of the materials highlight the need to achieve a minimum surface coverage of EtOH on the surface of the catalyst to control the reaction pathway. The adsorption of EtOH is a key factor in boosting the catalytic activity of the best-performing catalyst and producing CH4 from CO2 photoreduction and C2H4O from the photooxidation of EtOH, obtaining two easily separable interesting products for industrial applications in one reaction.
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| 3. |
- Chiango, Ludovica Beatrice, et al.
(författare)
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Simulation of an industrial scale scCO2 beam dyeing process
- 2022
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Ingår i: Journal of CO2 Utilization. - : Elsevier BV. - 2212-9820 .- 2212-9839. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- An industrial dyeing process in supercritical carbon dioxide has been modelled with computational fluid dynamics using Ansys Fluent software. In order to investigate the distribution of the dye carrier fluid, the flow resistance of the fabric has been accurately characterised. For this purpose, in the first part of the work a plain-woven fabric geometry was created in the open software Tex-Gen and modelled in Ansys Fluent to predict the permeation of fluid through the pores of the fabric material and to estimate the relationship between local fluid velocity and pressure drop. The second part of the study focused on evaluating the influence of beam structure, inlet flow rate, fabric height on the fluid flow through the fabric, which must be uniform to achieve a homogeneous level of dyeing. From the simulations the main obstacle to achieving a uniform flow velocity in the fabric is the pressure rise that occurs in the beam and creates a slight difference in permeation velocity between the two axial ends of the fabric; other disturbances, such as the effect of the perforated structure of the beam, are usually minor. Due to the low viscosity of supercritical carbon dioxide, inertial losses predominate over viscous losses in the porous medium. This means that approaches based only on the permeability of the fabric and the application of Darcy's law are inadequate to correctly predict the response of a dyeing unit when using carbon dioxide.
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| 4. |
- Cordova, Stephanie, 1988-, et al.
(författare)
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What should we do with CO₂ from biogas upgrading?
- 2023
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 77
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Tidskriftsartikel (refereegranskat)abstract
- Carbon capture and utilization has been proposed as an essential climate change mitigation strategy, but only a few implemented cases exist. During biomethane production from anaerobic digestion, CO₂ is commonly separated and emitted into the atmosphere, which can be utilized as raw material for various products. This research aims to identify and assess CO₂ utilization alternatives for possible integration with biogas upgrading from anaerobic digestion by developing a soft multi-criteria analysis (MCA). A literature review complemented with stakeholder participation enabled the identification of relevant alternatives and criteria for assessment. Potential alternatives for CO₂ utilization include methane, mineral carbonates, biomass production, fuels, chemicals, pH control, and liquefied CO₂. Results show that although no alternative performs well in all indicators, there is an opportunity for short-term implementation for methane, biomass production, mineral carbonates, liquefied CO₂, and pH control. Moreover, the uncertainty analysis reveals that even though the technologies have a high technological development, more information on critical aspects is still required. The soft MCA provides information to decision-makers, practitioners, and the academic community on learning opportunities of the alternatives and indicators to step from development into implementation. For instance, the method can be used to assess more specific systems with different locations and scales or to direct efforts to ease the implementation of CCU.
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| 5. |
- Deshpande, Swapnil S., et al.
(författare)
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Investigating CO2 storage properties of C2N monolayer functionalized with small metal clusters
- 2020
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Ingår i: Journal of CO2 Utilization. - : ELSEVIER SCI LTD. - 2212-9820 .- 2212-9839. ; 35, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- By using first principles calculations based on density functional theory (DFT), we studied a mechanism for the efficient capture of multiple CO2 molecules on TMn doped C2N monolayer (TMn = Ti-n and Sc-n with n = 1-3). A comprehensive analysis revealed that all the metal clusters bind strongly to C2N monolayer; however the bindings of Sc-n are stronger than those of Ti-n clusters. On the basis of electronic structure calculations, it was found that uniformly distributed metal clusters transformed the semiconducting C2N monolayers into metal. The magnetic states of C2N also changed from non-magnetic to magnetic upon the introduction of metal dopants. We found that a maximum of six CO2 molecules could be adsorbed on C2N doped with dimers and trimers of both Sc and Ti clusters. Our van der Waals corrected DFT calculations showed that the average binding energies per CO2 molecule decreased with the increase in the number of incident CO2 molecules to metal functionalized C2N. Overall, Sc-n doped C2N monolayer anchored the CO2 molecules stronger than that of Ti-n doping. We believe that these findings would pave the way for the synthesis of efficient CO2 capture medium.
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| 6. |
- Farooqui, Azharuddin, et al.
(författare)
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Techno-economic and exergetic assessment of an oxy-fuel power plant fueled by syngas produced by chemical looping CO2 and H2O dissociation
- 2018
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 27, s. 500-517
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Tidskriftsartikel (refereegranskat)abstract
- Natural Gas Combined Cycle (NGCC) is presently the most efficient fossil fuel power plant but with no carbon capture. The efficiency penalty resulting from the integration of carbon capture and storage (CCS) is, however, a major challenge. The present study proposes an oxyfuel NGCC integrated with Chemical looping (CL) syngas production (OXY-CC-CL), for power generation with CCS. The chemical looping CO2/H2O dissociation would produce syngas (CO and H-2 with methane reduction step in redox cycle) from recycled exhaust gas for additional power generation within the power plant. This integration of CL unit with the existing conventional oxy fuel power plant would be expected to decrease the efficiency penalty. Therefore, the thermodynamic (both energetic and exergetic), economic and environmental performance of the integrated chemical looping unit oxyfuel NGCC power plant with carbon capture were assessed. A 500 MW scale plant was modelled and compared with a conventional NGCC and oxyfuel NGCC plant with carbon capture (OXY-CC). The net efficiency penalty of the proposed OXY-CC-CL unit was 4.2% compared to an efficiency penalty of 11.8% of the OXY-CC unit with a 100% carbon capture. The energetic efficiency obtained hence was 50.7%, together with an exergetic efficiency of 47.1%. Heat integration via pinch analysis revealed the possibility to increase the system energetic efficiency up to 61%. Sensitivity analyses were performed to identify relative impacts of system operational parameters. The specific capital cost of the proposed OXY-CC-CL was obtained as 2455 $/kW, with a corresponding LCOE of 128 $/MWh without carbon credits.
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| 7. |
- Hossain, SK Saddam, et al.
(författare)
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Recent progress of geopolymers for carbon dioxide capture, storage and conversion
- 2023
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 78
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Forskningsöversikt (refereegranskat)abstract
- Geopolymer materials have garnered considerable interest as one of the most promising eco-friendly inorganic options over the last decade, thanks to their remarkable properties, including mechanical, chemical, and thermal stability, cost-effectiveness, and sustainable synthesis process, enabling their use in numerous high-value applications. Meanwhile, the ever-increasing concentration of CO2 in the atmosphere is an urgent concern for the environment and human health, forcing the development of effective CO2 capture, storage, and transformation strategies. Various potential solutions for reducing carbon emissions have emerged with the advancement of novel materials and technologies for CO2 capture from exhaust streams and air. Concurrently, significant studies have been conducted on utilizing geopolymers as a sustainable material for CO2 capture. This review provides a comprehensive overview of geopolymers’ recent advances and obstacles for CO2 management. We focus on state-of-the-art geopolymer foams and their composites, highlighting their potential for capturing CO2. In addition, we review the use of geopolymers as catalysts or precursors for converting CO2 into value-added chemicals and their potential for geological CO2 sequestration. Moreover, we analyze the current limitations and opportunities for further development of geopolymers in CO2 management. The review provides a perspective on the role of geopolymers in mitigating CO2 effects on the environment and advancing a sustainable future.
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| 8. |
- Nikjoo, Dariush, 1977-, et al.
(författare)
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Structured emulsion-templated porous copolymer based on photopolymerization for carbon capture
- 2017
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 21, s. 473-479
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Tidskriftsartikel (refereegranskat)abstract
- Porous hydrogel copolymers of acrylamide (AAM) and acrylic acid (AAC) were structured in the form of monoliths and granules. AAM-co-AAC porous copolymer monoliths were synthesized using high internal phase emulsion (HIPE) as template and photopolymerization. For granulation, photopolymerization was used for the fabrication of the AAM-co-AAC hydrogel, which was subsequently freeze-granulated. The structural analysis (FTIR and XRD) confirmed the successful synthesis of hydrogel copolymers. The CO2 uptake capacity of structured AAM-co-AAC copolymers was evaluated through adsorption and absorption mechanisms by volumetric and gravimetric methods, respectively. The granules exhibited the CO2 adsorption uptake of 0.8 mmol g-1 at 25 kPa and 298 K. The CO2 and N2 adsorption data demonstrated that the hydrogel copolymers were selective for CO2. Furthermore, the granules were capable of capturing CO2 in the presence of water. The results of absorption of CO2 on water-swollen granules demonstrated that CO2-uptake capacity increases with increasing water content up to 1.8 mmol g-1.
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| 9. |
- Zhang, Zhibo, et al.
(författare)
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Electrochemically driven efficient enzymatic conversion of CO2 to formic acid with artificial cofactors
- 2021
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- Enzymatic reduction of CO2 to formic acid with the enzyme formate dehydrogenase (FDH) and a cofactor is a promising method for CO2 conversion and utilization. However, the natural cofactor nicotinamide adenine dinucleotide (NADH) shows some drawbacks such as a low reduction efficiency and forms isomers or dimers (1,6 - NADH or NAD dimer) in the regeneration reaction. To overcome them and to improve the production of formic acid, in this work, the artificial cofactors, i.e., the bipyridinium-based salts of methyl viologen (MV2+), 1,1’-dicarboxymethyl-4,4’-bipyridinium bromine (DC2+), and 1,1’-diaminoethyl-4,4’-bipyridinium bromine (DA2+), were used to replace NADH, and the effect of different functional groups on the electrochemical regeneration and catalytic performance in the enzymatic reaction was studied systematically. Also, studies using the natural cofactor NADH were carried out for comparison. It was found that the cofactor with amino groups showed the highest catalytic efficiency (kcat/Km) of 0.161 mM-1min-1, which is 536 times higher than that of the natural cofactor NADH. Molecular Dynamics simulations were conducted to give further molecular insight into the behavior of the cofactors. Analyzing the free energy profiles of the complexes between CO2 in the FDH active site with different artificial cofactors indicated that the artificial cofactor with the amino groups had the highest affinity for CO2, being consistent with the experimental observations.
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| 10. |
- Zhang, Zhibo, et al.
(författare)
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Novel artificial ionic cofactors for efficient electro-enzymatic conversion of CO2 to formic acid
- 2022
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- The low yield of enzymatic conversion of CO2 to formic acid as well as the high cost and instability of using the natural cofactor (NADH) hamper the large-scale application of the CO2 enzymatic utilization. To address these issues and to improve the production of formic acid, six bipyridinium-based artificial cofactors were developed for the enzymatic conversion of CO2 and further integrated with the electrocatalytic regeneration of the cofactors for the formic acid production. All of them did show a higher catalytic performance compared to NADH. Particularly, 1,1′-bis(2-(dimethylamino)ethyl)-4,4′-bipyridinium bromine did exhibit the highest catalytic performance with a high formic acid concentration of 4.76 mM in 60 min, which is 47 times higher than that of the natural cofactor NADH and is also currently the highest performance among the reported artificial cofactors in literature. Thermodynamic analysis, electrochemical investigations, and molecular dynamics simulations were performed to clarify the structure-energy relationship of the functional bipyridinium-based salts and to rationalize how it is affected by the different functional groups. This study gives a deep insight into the role of artificial cofactors in enzymatic reactions and can clearly promote the development of novel bioelectrochemical conversion of CO2.
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