Low Desorption Research Articles

Redistribution of ices between grain populations in protostellar envelopes. Only the coldest grains get ices

Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of ices that accumulated during the prestellar phase. We explore the fate of ices on multiple-sized dust grains in a parcel of infalling matter. A comprehensive kinetic chemical model using five grain-size bins with different temperatures was applied for an infalling parcel. The parcel was heated to 150,K and then cooled over a total timescale of 20,kyr. Effects on ice loss and re-accumulation by the changed gas density, the maximum temperature, the irradiation intensity, the size-dependent grain temperature trend, and the distribution of the ice mass among the grain-size bins were investigated. A massive selective redistribution of ices exclusively onto the surface of the coldest grain-size bin occurs in all models. The redistribution starts already during the heating stage, where ices that are sublimated from warmer grains re-adsorb onto colder grains before complete sublimation. During the cooling stage, the sublimated molecules re-freeze again onto the coldest grains. In the case of full sublimation, this re-adsorption is delayed and occurs at lower temperatures because a bare grain surface has lower molecular desorption energies in our model. Most protostellar envelope grains enter the PPD ice poor (bare). Ices are carried by a single coldest grain-size bin, here representing 12,% of the total grain surface area. This bare ice-grain dualism can affect the rate of the grain coagulation. The ice components are stratified on the grains according to their sublimation temperatures.

Mitigating cadmium contamination in soil using Biochar, sulfur-modified Biochar, and other organic amendments

Biochar is a novel approach to remediating heavy metal-contaminated soil. Using various organic amendments like phyllosilicate-minerals (PSM), compost, biochar (BC) and sulfur-modified biochar (SMB), demonstrates superior adsorption capacity and stability compared to unmodified biochar (BC). The adsorption mechanisms of SMB are identified for its potential to increase soil-pH and reduce available cadmium (Cd). The study reveals the potential of BC and SMB in immobilizing Cd in contaminated soil. SMB demonstrated the highest adsorption capacity for Cd, followed by BC, PSM, and compost, with capacities ranging from 7.47 to 17.67 mg g−1. Both BC and SMB exhibit high adsorption capacities (12.82 and 17.67 mg g−1, respectively) and low desorption percentages (4.46–6.23%) at ion strengths of 0.01 to 0.1 mol-L−1 and pH levels ranging from 5 to 7. SMB showed a higher adsorption capacity (17.67 mg g−1) and lower desorption percentage (4.46–6.23%) compared to BC. The adsorption mechanism involves surface-precipitation, ion exchange, and the formation of Cd(OH)2 and CdCO3 precipitates, as well as interactions between Cd and organic sulfur, leading to more stable-Cd and CdHS+ compounds. Adding 1% SMB increased soil pH and significantly reduced available Cd, demonstrating its potential for pollutant remediation. The study underscores the promise of SMB in providing a sustainable solution for Cd-contaminated soil remediation.

Efficient Oxidative Removal of Indoor Formaldehyde Using Functionalized Activated Alumina.

Formaldehyde (HCHO) has become a significant indoor air pollutant, arising from the widespread use of decorative and construction materials. Adsorption is the most convenient method for HCHO removal. However, the current adsorption is limited by the current low adsorption capacity and desorption. Herein, activated alumina (γ-Al2O3) loaded with permanganate was proposed for the efficient oxidative removal of indoor HCHO. The results demonstrate that the permanganate-containing alumina-based pellets (PAP) with 75% of alumina (PAP-75) displayed the highest adsorption capacity of 10,800 μg g-1. This high adsorption capacity is mainly attributed to the presence of numerous pore structures within the pellets, good dispersion of permanganate on the surface and inside the spheres, abundant surface-active sites, and high porosity. The adsorption kinetics explains that the chemisorption, intraparticle diffusion, and film diffusion are the primary rate-controlling steps. This study provides an effective strategy for further improving alumina-based adsorption materials for HCHO removal.

Acetamiprid retention in agricultural acid soils: Experimental data and prediction.

The overuse of pesticides in agriculture has led to widespread pollution of soils and water resources, becoming a problem of great concern. Nowadays, special attention is given to neonicotinoids, particularly acetamiprid, the only neonicotinoid insecticide allowed for outdoor use in the European Union. Once acetamiprid reaches the soil, adsorption/desorption is the main process determining its bioavailability and environmental fate. Therefore, in this work, the adsorption/desorption behaviour of acetamiprid in 60 agricultural soils was studied. The results indicate that acetamiprid has a low affinity for soil constituents, with values ranging from 0.2 to 4.28 L kg-1 for Kd(ads). At the same time, acetamiprid shows high desorption levels (up to 96.3%), indicating that it is poorly retained in soils, thus presenting high bioavailability and a potential risk for transport to other environmental compartments. Regarding the influence of soil properties on the adsorption/desorption process, soils with a high content of organic matter, clay, and exchangeable basic cations showed higher retention of acetamiprid, with greater adsorption and lower desorption. Finally, robust and universal models were successfully developed to predict the adsorption and desorption behaviour of acetamiprid in soil.

Adsorption of Sinapine from Rapeseed Protein Production Effluent to Cation Exchange Resins

Sinapine adsorption was studied on four weak cation exchanges at pHs ranging from 2 to 8. The best adsorption rate was observed with C106 resin at pH 4 (95.25%). The adsorption kinetics followed a pseudo-second-order model while the isotherm data better fitted the Langmuir model. The ΔG°, ΔH°, and ΔS° values (−25.834 kJ·mol−1, −24.428 kJ·mol−1, and 0.004 kJ·mol−1·K−1) revealed that the adsorption process was spontaneous and exothermic. Acidified ethanol showed a better desorption rate (75.41%), while virtually no (3.32%) or low (31.14%) sinapine desorption was observed with 50% ethanol and 0.1 M HCl solution, respectively. This indicated that sinapine adsorption took place throughout both ionic and hydrophobic interactions. Very close sinapine adsorption performances were observed with an effluent of the patented rapeseed protein isolate process. Two-step desorption using 50% ethanol, then acidified ethanol, yielded a highly purified neutral sinapine-derivative phenol fraction (75.23%) in the first elution fraction and sinapine (98.85%) in the second one.

Hydration and Antibiofouling Behavior of Zwitterionic Polycarboxybetaine-Grafted Surfaces Studied with Atomistic Simulations.

Fouling-resistant coating materials have important applications in marine industry and biomedicine. Zwitterionic carboxybetaine polymers have demonstrated robust antibiofouling functionalities in experiments. In this work, we performed atomistic molecular dynamics simulations to study the molecular mechanism of hydration and antibiofouling of poly(carboxybetaine acrylamide) (polyCBAA) brush surfaces. We focused on the zwitterionic carboxybetaine, which has only a short methylene spacer between the positive quaternary ammonium and the negative carboxylate groups. Our study shows that a large amount of water is present within the polyCBAA surface, and a condensed water layer of single-molecular thickness covers the top of the polymer surface. Moreover, the clustering of the zwitterionic chains results in an amorphous structure of the polymer surface, a reduced degree of order in the interfacial water molecules, and weak protein attachment. The low protein desorption free energy demonstrates that the polyCBAA surface exhibits strong fouling resistance due to its significant interfacial hydration and the small dipole moment of the carboxybetaine group, minimizing protein-surface electrostatic interactions. Our study at the molecular level will be important to the future development of zwitterionic materials.

Investigation on the effect of Co doping on structure, electronic, and hydrogen storage properties of Mg2FeH6

Metal hydrides, particularly magnesium-based materials, exhibit excellent hydrogen storage capabilities. Among these, Mg2FeH6 stands out for its high hydrogen storage capacity, but it faces limitations due to low thermodynamic stability and high hydrogen desorption temperature. To overcome these challenges, we investigated the potential of Co doping to improve hydrogen storage properties. Based on first-principles calculations, we systematically explored the structures, electronic properties and hydrogen storage capabilities of a novel Mg-Fe-Co-H alloy. We found that Co doping significantly reduced the band gap by 1.14 eV, promoting electron transitions and accelerating hydrogen desorption kinetics. Additionally, Co doping alters the Fe-H interaction, increasing bond lengths and facilitating the hydrogen dissociation. Although Co doping slightly decreases hydrogen storage capability of Mg2FeH6 (from 5.45 wt% to 5.32 wt%), it significantly lowers desorption temperature from 651 K (Mg2FeH6) to 543 K (Mg2Fe1/8Co7/8H6). This study highlights the innovative potential of Co doping to enhance the performance of Mg2FeH6-based hydrogen storage materials, offering promising prospects for advancing hydrogen energy technologies.

Desorption of Antibiotics from Granular Activated Carbon during Water Treatment by Adsorption

Although desorption of adsorbed pharmaceuticals from granular activated carbon (GAC) may inadvertently lead to their partial discharge with adverse effects on aquatic environments, there have only been a few reports of this phenomenon. This study has investigated desorption of antibiotics vancomycin and rifampicin from activated carbon in aqueous media regarding contact time and pH regime. Various characterizations of the three types of GAC were investigated. Then, antibiotics were loaded on them via adsorption. Subsequently desorption and re-adsorption of antibiotics were quantified for a range of contact times and ambient pH values. Within the first hour of a reversed concentration gradient at neutral pH, desorption released 2% to 54% of previously adsorbed antibiotics to water, which were subsequently re-adsorbed within 24 hours to four weeks with less than 1% antibiotics remaining in the liquid phase. Lower desorption was positively associated with higher GAC mesopore content and larger specific surface area. Effects of the ambient pH regime varied between studied adsorbents. The results are evidence that mesopore content and pore size in relation to the kinetic diameter of adsorbate molecules are important determinants of the extent of antibiotic desorption from GAC and the rates of subsequent re-adsorption. Physisorption was the dominant mechanism involved in both processes. Observed proportions and rates of antibiotic desorption suggest that selection of GAC properties should also consider their effects on unintended desorption and the re-adsorption during treatment processes in order to minimize potential pollution discharge or promotion of antibiotic resistance during treatment processes.

Scalable Synthesis of AgCl-Derived Ag Structures for Electrochemical CO2 Reduction

Electrochemical CO2 reduction reaction (CO2RR) has the potential to serve as a competent technology capable of reducing the CO2 levels in the atmosphere while utilizing renewable energy. The CO generated from the CO2RR forms a component of syngas (CO/H2), which is highly demanded in the market and industry, recognized for its value as a chemical feedstock. However, to achieve an industrial-level current density, improvement in the CO2-to-CO catalyst is necessary. Au, Ag, and Zn exhibit high CO selectivity in the CO2RR due to their low CO desorption energy barrier and poor hydrogen binding energy, showing over 90% FE of CO. Particularly, Ag is considered a promising catalyst due to its high durability, selectivity, and moderate price. However, it fails to suppress HER at high potential and current regions, limiting the incretion in CO current density.In this study, we developed a scalable AgCl nanocube catalyst for the CO2RR using a sonochemistry-based method. The AgCl nanocube achieved a CO current density of over 400 mA cm-2 in a 0.1 M KHCO3 electrolyte using an MEA cell. AgCl releases Cl and forms Ag surface through an electrochemical reduction process, resulting in AgCl-derived Ag catalysts. This AgCl-derived surface possesses high porosity, enhancing CO2 mass transfer, and promote CO2 adsorption through charged surfaces, leading to high CO current density. The uniform AgCl nanocube catalyst, which can be synthesized on a gram scale under mild conditions, offers cost-effective and rapid catalyst supply. During the reduction process, the AgCl nanocubes break into smaller particles, resulting in an AgCl-derived Ag catalyst with an increased surface area. Surface spectroscopic analysis revealed enhanced CO2 adsorption and the presence of Cl remaining on the catalyst surface. As a result, the AgCl nanocube successfully suppressed HER at high potential regions, maintaining a high level of CO selectivity, thereby increasing the productivity of CO2-to-CO electroreduction. A rapid and scalable synthetic method for nanoparticle that simultaneously obtains a reagent (Cl) that enhances the reaction and a CO2RR catalyst (Ag) could provide insights for future catalyst development.

Time-efficient atmospheric water harvesting using Fluorophenyl oligomer incorporated MOFs

Adsorption-based atmospheric water harvesting (AWH) has the potential to address water scarcity in arid regions. However, developing adsorbents that effectively capture water at a low relative humidity (RH < 30%) and release it with minimal energy consumption remains a challenge. Herein, we report a fluorophenyl oligomer (FO)-incorporated metal-organic framework (MOF), HKUST-1 (FO@HK), which exhibits fast adsorption kinetics at low RH levels and facile desorption by sunlight. The incorporated fluorophenyl undergoes vapor-phase polymerization at the metal center to generate fluorophenyl oligomers that enhance the hydrolytic stability of FO@HK while preserving its characteristic water sorption behavior. The FO@HK exhibited vapor sorption rates of 8.04 and 11.76 L kg−1MOF h−1 at 20 and 30% RH, respectively, which are better than the state-of-the-art AWH sorbents. Outdoor tests using a solar-driven large-scale AWH device demonstrate that the sorbent can harvest 264.8 mL of water at a rate of 2.62 L kg−1MOF per day. This study provides a ubiquitous strategy for transforming water-sensitive MOFs into AWH sorbents.

Enhanced and prolonged adsorption of ammonia gas by zeolites derived from coal fly ash.

In this study, zeolites were synthesized from coal fly ash (CFA) using NaOH (Na-X type) and KOH (chabazite-K type) and used for the adsorption of ammonia gas in a fixed-bed reactor. Magnetic separation was used to decrease the Fe impurity content from 6.84 to 2.37 wt.%, and to increase the Si and Al content in non-magnetic fly ash (NMFA). BET surface areas of the zeolites increased significantly to 425.28 m2/g with an increase in micropore volume (ca. 0.12 cm3/g). FTIR and NH3-TPD analyses revealed that the increased surface area provided more acidic sites for enhanced ammonia gas adsorption. In particular, the zeolite (i.e., ZNF-X) synthesized from NMFA and NaOH showed the highest ammonia gas adsorption capacity (64.9 mg/g), owing to its high BET surface area and micropore volume. Although the initial adsorption capacity of commercial 13X zeolite (74.5 mg/g) was higher than that of ZNF-X, a much higher recycling efficiency for ZNF-X (92.0%) was achieved than for 13X (31.5%) during the five recycling tests because of the lower ammonia desorption temperature of ZNF-X. The results provide new insights into the synthesis of zeolites by upcycling of CFA and demonstrate the potential use of the generated materials for enhanced and prolonged removal of ammonia gas.

Optimizing hydrogen storage in magnesium hydride using carbon-based catalysts

Abstract The utilization of fossil fuels, including coal, crude oil, and natural gas, has long been recognized as a significant contributor to environmental degradation, primarily due to their non-renewable nature and harmful emissions. The transition to renewable energy sources becomes imperative, and energy storage technologies are of paramount importance. In this context, hydrogen as chemical energy storage emerges represent a promising solution, offering both sustainability and environmental friendliness. However, the practical storage of hydrogen presents several challenges, primarily due to its light weight and gaseous nature. Among various storage methods, magnesium hydride (MgH2) has gained considerable attention due to its high hydrogen storage capacity, reversible uptake and release, and potential for safe handling and transportation. Nevertheless, magnesium hydride face inherent drawbacks, including low sorption and desorption kinetics, high hydrogen release temperatures, and the formation of undesirable gases during cycling. To overcome these challenges, various strategies have been proposed, with catalytic enhancement showing significant promise. Carbon-based materials and carbon-based composite materials have emerged as effective catalysts in improving the kinetics and efficiency of hydrogen storage in magnesium hydride. In this paper, that is a review of the existing literature, the role of these carbon-based catalysts in enhancing the performance of magnesium hydride for hydrogen storage will be explored, focusing on recent advancements and potential solutions to overcome existing limitations.

MOFs derived Ni-Mn bimetal nano-catalysts with enhanced hydrogen pump effect for boosting hydrogen sorption performance of MgH2

In the present work, highly effective Ni-MnO binary nanocomposite catalysts were designed and synthesized using a one-pot method from Ni-Mn based bi-metal organic frameworks (MOFs). These nanocomposites were introduced into MgH2 through ball milling as catalysts to enhance the hydrogen storage properties of MgH2. Through varying the Ni/Mn ratio in the bimetal MOFs, it is found that the Ni1Mn1−MOF derived catalyst showed the best promotion effect on MgH2. The MgH2–10 wt.% Ni1Mn1−MOF derivative demonstrated favorable overall performance with the low desorption peak temperature (218.2 °C) with a saturated hydrogen capacity of 6.42 wt.% and rapid hydrogen release/uptake kinetics. It can still reabsorb about 1.15 wt.% H2 within 30 min at a temperature as low as 50 °C. Both performance tests (DSC and TPD) and structural characterizations (XRD, HRTEM, etc.) revealed that the synergistic role of in situ formed Mg6MnO8 and Mg2NiH4/Mg2Ni phases for improving the hydrogen sorption properties of MgH2. Theoretical calculations reveal that Mg6MnO8 destabilizes metal-H bonds in MgH2 and Mg2NiH4, leading to an enhanced “hydrogen pump” effect of Mg2NiH4 for MgH2. This research provides a strategy to rational design and preparation of bimetal MOF derivatives for the development of advanced hydrogen storage materials.

Single-Particle Spectroelectrochemistry: Revealing the Electrochemical Tuning Mechanism of Chemical Interface Damping in 1,2-Benzenedithiol-Adsorbed Single Gold Nanorods.

Chemical interface damping (CID) is a newly proposed plasmon damping pathway based on interfacial hot-electron transfer from metal to adsorbate molecules. However, achieving in situ tunability of CID in single gold nanorods (AuNRs) remains a considerable challenge. Here, we present the CID effect induced by benzene 1,2-dithiol (BDT) molecule adsorption on single AuNRs and the effective electrochemical tunability of CID in BDT-adsorbed AuNRs immobilized on an indium tin oxide (ITO) surface. Manipulations of the electrochemical potential alter the electron density of AuNRs, thereby influencing and tuning the localized surface plasmon resonance (LSPR) spectrum, with cathodic potential blueshifting and anodic potential redshifting. The strong adsorption of BDT on Au induced CID in single AuNRs. The potential-induced LSPR scattering spectra of BDT-adsorbed AuNRs for linear potential sweep showed a stable LSPR spectral response, irrespective of the concentrations of BDT molecules. Due to the involvement of two Au-S bonds, BDT molecules have a higher free adsorption energy and a lower desorption rate on the Au surface. This resulted in a stable LSPR spectral response for a linear electrochemical potential sweep. Furthermore, a constant anodic and cathodic potential application showed the tunability of the CID at the BDT-Au interface.

Effect of CO2 injection pressure on enhanced coal seam gas extraction

The CO2 displacement of coal seam gas can simultaneously promote gas extraction and CO2 sequestration, with gas injection pressure being a key factor influencing both efficiency and safety. This study examined the impact of varying CO2 injection pressure on gas extraction and sequestration. The findings indicated that higher CO2 injection pressures reduced the gas injection and extraction time costs, increased the equilibrium pressure and coal seam temperature, and decreased carbon sequestration efficiency. As the CO2 injection pressure increased, the CH4 cumulative desorption capacity and desorption rate rose by 4.98%, the time to reach the residual gas content critical value (TLV of 2 m3/t) shortened by 62.04 min, and the maximum CO2 storage per unit mass of coal increases by 3.6 m3/t. Increasing the injection pressure enhanced gas desorption and CO2 sequestration. A higher CO2 injection pressure resulted in a higher CH4 yield rate and a reduced CO2 injection rate in the later stages. Therefore, it is advisable to reduce the CO2 injection pressure during the low efficiency desorption stage.

Exploring complete catalytic cycle of methane oxidation to methanol on Cu2O2 stabilized within MIL-53(Al) framework: A combined DFT and microkinetic study

Although inspiration from copper-based natural enzymes has shown promise in improving catalyst design for methane-to-methanol (MTM) oxidation, high productivity, and selectivity under mild conditions remain a significant challenge. This study constructs the dinuclear copper (Cu2) species stabilized within the metal-organic framework (MOF), MIL-53(Al), containing Cu as efficient catalytic sites and explores the ability of different oxidants (O2, N2O, and H2O2) to oxidize Cu2 into the dicopper-oxo (Cu2O2) species using density functional theory (DFT) calculations. Our results indicate the kinetic and thermodynamic favorability of Cu2O2 species formation using O2 as an oxidant within the MIL-53(Al) framework. Furthermore, the thermal stability of Cu2O2/MIL-53(Al) has been verified via ab initio molecular dynamics (AIMD) calculations. The kinetics of the complete MTM oxidation cycle over Cu2O2/MIL-53(Al) have been studied using both DFT and microkinetic simulation methods. The present study predicts that the C-H activation on the Cu2O2/MIL-53(Al) has a low free energy barrier (0.77 eV) and that the high stability of CH3 and its very low free energy barrier in the C-O coupling step favors the methanol formation over the formaldehyde. More importantly, Cu2O2/MIL-53(Al) exhibits high methanol selectivity owing to the inhibition of CH3 dehydrogenation and low methanol desorption energy (0.21 eV). Microkinetic simulations confirm the methanol production under relatively mild reaction conditions (200–280 K and 1 bar). This work provides insights into the feasibility of selective MTM oxidation over this family of MOF under mild conditions.

Effect of activation temperature on photon-stimulated desorption from Ti-Zr-V coated copper chambers

Non-evaporable getter (NEG) films featuring distributed pumping properties and low photon-stimulated desorption (PSD) are widely utilized in particle accelerators, especially in diffraction limited storage rings (DLSR) with compact design. Activation is a requisite operation to sustain the pumping capacity of NEG films. Meanwhile, the vacuum properties of NEG films vary with activation temperature. In this work, the dependence of the PSD from NEG films is evaluated with the activation temperature. The columnar Ti-Zr-V films were deposited on the inner surface of the copper vacuum chamber by DC magnetron sputtering. The effect of activation temperature ranging from 150 to 200 °C and nitrogen venting on the PSD of Ti-Zr-V films was investigated. The results indicate that with elevating the activation temperature, the initial PSD yield of the Ti-Zr-V coated chamber consistently declines. Furthermore, the initial desorption of Ti-Zr-V films after nitrogen venting is between that of the non-activated state and the activated state.

Structure analysis (XRD and Neutrons) and hydrogen storage properties of Hf1-xTixNbVZr BCC high entropy alloys

The hydrogen storage properties of Hf1-xTixNbVZr high entropy alloys (HEAs) synthesized by arc melting have been investigated. The first hydrogenation of the alloys was performed at room temperature under 20 bars of hydrogen pressure. Results show an increase in gravimetric hydrogen content with Ti substitutions. Upon hydrogenation, the multiphase alloys (x = 0 and x = 0.25) exhibit a combination of faces-centred-cubic (FCC) hydride and C15 Laves phases, while single-phase alloys (x = 0.5, 0.75, and 1) display FCC structures. The crystal structure evolution during dehydrogenation of HfNbVZr (x = 0) and TiNbVZr (x = 1) HEAs was examined using in-situ neutron diffraction. The analysis demonstrates temperature-dependent desorption behaviour, with HfNbVZr displaying lower desorption temperatures compared to TiNbVZr. Additionally, in-situ neutron diffraction experiments during deuterium desorption indicate a two-step phase transition from FCC dihydride to BCT monohydride, followed by a transition to BCC.

Research on CO2 capture performance and reaction mechanism using a novel low energy consumption and high cyclic performance absorbent for onboard application

High desorption energy consumption and low cyclic loading are critical issues limiting the application of onboard carbon capture (OCC) systems. In this study, a tetraethylenepentamine (TEPA) and 2–amino–2–methyl–1–propanol (AMP) mixed amine solvent with low desorption energy consumption and high CO2 cyclic loading, suitable for the operational environment of OCC systems, has been proposed. Detailed research was conducted on the capture performance and mechanism of the TEPA + AMP mixed amine solvent. The 0.25M TEPA+0.75M AMP mixed amine solvent exhibited the best performance, with an 86.5% increase in CO2 loading, a 214% increase in single–cycle CO2 loading, a 236% increase in CO2 loading after four cycles compared to monoethanolamine (MEA), and a 20.76% reduction in desorption energy consumption. In addition, to address the challenge of applying polyamine mixed solutions in the simulation studies of OCC systems, the capture mechanism was analyzed using density functional theory (DFT) calculations and nuclear magnetic resonance (NMR) characterization. The results indicated that increasing AMP promoted HCO3− formation in the TEPA + AMP mixed amine solvent. Since HCO3− decomposed more easily than carbamate, it reduced desorption energy consumption. However, an excess of AMP inhibited the absorption rate of TEPA, affecting the absorption capacity. Increasing the concentration of TEPA enhanced the amine concentration in the absorbent and improved the absorption performance. Nevertheless, excessive TEPA caused AMP to participate only in deprotonation reactions, which was not conducive to reducing desorption energy consumption.

Enhancing adsorbent performance for direct air capture of CO2 by in-situ amine-grafting of layered double hydroxides

The development of efficient and cost-effective CO2 adsorbents is crucial for carbon capture from ultradilute conditions. Amine-grafted mesoporous materials prepared by silane chemical reactions are well-known CO2 adsorbents with high thermal stabilities, but their capacities for direct air capture (DAC) are usually restricted by low amine loadings and CO2 capture capacity. Herein, we present an in-situ amine grafting method that enables high amine loadings by in-situ grafting initial ultrathin LDHs nanosheets in an organic solvent. For in-situ triamine grafted Mg2Al-CO3 LDH (IN-TRI-LDH) amine loading is boosted to 5.91mmol N g−1 and ultimately achieving a remarkable adsorption capacity of 0.98 mmol g−1 at 25°C and 400 ppm CO2, nearly double that of the amine-LDHs grafted through a conventional two-step process. A further 22 % enhancement of the CO2 capacity is observed under 20 RH%. In addition, IN-TRI-LDH maintains a working capacity of 0.85 mmol g−1 at a low desorption temperature of 70 °C. A 50 adsorption–desorption cyclic test under simulated humid DAC conditions shows minimal performance degradation. Such a sufficient working capacity and low desorption temperature reduces the thermal energy consumption to 2.27 GJ t−1 at a desorption temperature of 40 °C.