Uptake Capacity Research Articles

Mechanochemical carbonation of recycled concrete fines: Towards a high-efficiency recycling and CO2 sequestration

The relative slow carbonation efficiency for conventional wet and dry carbonation of recycled concrete fines (RCF) limits its resource industrial utilization. In this study, an innovative mechanochemical carbonation (MC) method was developed. The carbonation kinetics, phase assemblage and microstructure evolution of RCF during the MC process were extensively examined. The results exhibited a substantial enhancement in the carbonation efficiency and CO2 utilization rate, as evidenced by achieving a notable carbonation degree within 10 min. This accomplishment surpassed what could be achieved even after a prolonged 2 h period of wet carbonation, and the CO2 uptake capacity and utilization rate achieved via MC reached >0.3 g-CO2/g-RCF and 80 %, respectively. The superior performance of MC was ascribed to the influence of mechanochemical effects. These effects contributed to the refinement in the geometrical characteristics of RCF, exfoliation of the passivating layers, and facilitation of CO2 dissolution, which favored the structural disintegration of RCF and carbonation progress. Another distinctive aspect of MC treatment was the production of a greater proportion of metastable CC characterized by reduced crystalline size, which was attributed to modifications in the carbonation environment and the structural alterations induced by mechanochemical effects. Moreover, the precipitation of silica gels commenced at approximately 4 min in the MC process, a notably earlier onset when compared with wet carbonation; additionally, a greater abundance of silica gels was observed in the current MC procedure, resulting from the higher carbonation degree caused by mechanochemical effects. The encouraging conclusions in the present work validated the feasibility of producing carbonated RCF more efficiently and paved the way for future industrial practice.

Identification and validation of reference genes for RT-qPCR analysis in Iris domestica under Cd stress

Iris domestica is a widely used ornamental garden and important medicinal plant. Our previous studies have shown that it exhibits significant uptake and translocation capacity under Cd stress compared to other Iris species. Gene expression is studied using RT-qPCR; however, there are no reference genes have been found for I. domestica under Cd stress. In this investigation, thirteen possible reference genes from previous studies and our transcriptome were screened using RT-qPCR in the leaves and roots of Cd-stressed plants. The findings revealed that UBC9 and ACT were the best reference genes for roots with and without Cd stress, whereas YLS8 and ACT7 were the best reference genes for leaves. Among the different tissues without Cd stress, UBC9 and UBC28 exhibited the best results, whereas PP2C06 and UBC9 exhibited the best results under Cd stress. The most stable reference genes in the leaves and roots were UBC9 and UBC28, respectively, under and without Cd stress, and GADPH was the most unstable. Finally, three metal ion response genes, NRAMP2, YSL9 and CYP81Q32 were detected using RT-qPCR and compared with the transcriptome data to further confirm the reliability of the chosen genes. This study identified suitable reference genes for I. domestica under Cd-stress conditions.

Fabrication and application of magnetic MgFe2O4-OH@biochar composites decorated with β-ketoenamine for Pb(II) and Cd(II) adsorption and immobilization from aqueous solution

The excessive discharge of water contaminated by lead (Pb(II)) and cadmium (Cd(II)) seriously jeopardizes ecological security and needs to be addressed urgently. Herein, a novel, efficient and highly stable biochar-based magnetic adsorbent of KEA-MgFe2O4-OH@RSBC was fabricated via loading MgFe2O4-OH nanoparticles (NPs) on reed straw biochar (RSBC) surface followed by decorating with β-ketoenamine (KEA) to boost the capture efficiency of Pb(II)/Cd(II) from wastewater. Adsorption behavior and mechanism studies indicated that the abundant and diverse functional groups of KEA-MgFe2O4-OH@RSBC were favorable for Pb(II)/Cd(II) removal. The binding of KEA-MgFe2O4-OH@RSBC with Pb(II)/Cd(II) was increased mainly via complexation, electrostatic attraction, cation-π coordination, ion exchange and pore filling. Due to the incorporation of MgFe2O4-OH and KEA, the Pb(II) /Cd(II) uptake capacity by KEA-MgFe2O4-OH@RSBC reached up to 238.06/226.76 mg/g (pH=5.0, C0 = 180 mg/L). The XPS analysis showcased that the strong interactions between Pb(II)/Cd(II) and oxygen/nitrogen atoms in the composites played an important role for the adsorption of Pb(II)/Cd(II) by KEA-MgFe2O4-OH@RSBC. In addition, the evaluation study on the practical application potential of KEA-MgFe2O4-OH@RSBC manifested that the material exhibited strong resistance to ionic interference (R> 93 % in collected actual metal smelting wastewater). KEA-MgFe2O4-OH@RSBC had a good regeneration and reapplication capability (R> 82 % after 5 cyclic regeneration experiments). Besides, the stronger magnetism overcome the separation difficulty after adsorption from wastewater. In conclusion, KEA-MgFe2O4-OH@RSBC will be an ideal candidate for Pb(II)/Cd(II) removal from contaminated water systems. The present study would greatly contribute to the effective and sustainable progress of heavy metal remediation strategies.

Influence of enforced carbonation on alkali-silica reaction: Performance and multi-scale mechanisms

Alkali-silica reaction (ASR) has emerged as one of the major concrete deterioration issues. Despite the extensive effort investments in ASR mitigation, the interaction between ASR and carbonation remains unclear. To investigate the role and mechanisms of early-age enforced carbonation in ASR, enforced carbonation conditions at 50 °C and 95 % RH with different CO2 concentrations up to 20 % were employed at two stages. The ASR mitigation efficacy was evaluated by monitoring the volume expansion and cracking behavior of mortars containing reactive aggregates. A comprehensive understanding was obtained by analyzing the evolutions of ASR gel's composition, molecular structure, and hygroscopicity. The results indicate that ASR can be effectively suppressed under carbonation with a 97.9 % decrease in ASR-induced volume expansion and fully suppressed cracking when the mortars were cured at 20 % CO2 for 30 days. The decreases in the Q3 polymerization sites and [K + Na]/Si ratios of the ASR products, as well as the 30.3 % reduction in water uptake capacity of ASR gels under carbonation, uncovered the underlying mechanisms for the mitigated ASR at multiple length scales.

Oxidation and compositional modulation in single phase C14 Zr0.6Ti0.4Fe1Cr1 alloy

This study investigates the effects of heat treatment on the crystal structure and hydrogen absorption behavior of the AB2 type metal hydride Zr0.6Ti0.4Fe1Cr1. The objective is to understand how 3- and 6-day heat treatments at 1000°C influence the alloy's microstructure and hydrogenation properties. Using electron microscopy, EBSD analysis, X-ray diffraction, and hydrogenation measurements, we found that the as-cast alloy exhibits rapid hydrogen absorption with significant compositional variations due to segregation during casting, confirmed by a single C14 Laves phase in XRD. Heat treatment slowed hydrogen absorption and reduced hydrogen capacity, with XRD indicating the structure remained primarily C14 Laves phase. However, SEM/EDS analysis showed substantial microstructural changes, including the emergence of new phases and segregation of Zr-rich phases, likely non-hydride forming, influenced by elevated oxygen content. These new phases probably contribute to the reduced hydrogen uptake capacity.

Effects of long-term nighttime warming on extractable soil element composition in a Mediterranean shrubland

Understanding the soil biogeochemical responses to increasing global warming in the near future is essential for improving our capacity to mitigate the impacts of climate change on highly vulnerable Mediterranean ecosystems. Previous studies have primarily focused on the effects of warming on various biogeochemical processes. However, there is limited knowledge about how the changes in water availability associated to high temperatures can alter the bioavailability and dynamics of soil elements, thereby impacting ecosystem productivity, species composition, and pollution through soil biogeochemical and hydrological processes. In this study, we investigated the effects of long-term nighttime warming on the extractable concentrations of organic carbon (EOC), total nitrogen (ETN), total phosphorus (ETP), and 17 mineral elements (arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), sulfur (S), strontium (Sr), vanadium (V), and zinc (Zn)) through environmental experiments in a semi-arid Mediterranean shrubland. We explored the potential biotic and abiotic mechanisms underlying the seasonal and long-term changes in extractable-mobilizable elemental composition and concentrations. Our findings revealed that prolonged warming led to higher mean annual soil temperature (with an average increase of 0.67 °C from 1999 to 2014), accumulation of soil organic matter (EOC) and extractable concentrations of soil elements (particularly increased ETP and extractable Ca, Mg, Cu, Sr, Mn, and As). These changes were attributed to uniformly higher activities of extracellular soil enzymes and/or lower plant photosynthetic and nutrient uptake capacity linked to more water deficit under warmer conditions. Seasonality unevenly altered element extractable concentrations, with soil microclimate (temperature and water content) and biological (soil microbial and plant) activity being the main drivers of this variability, thus influencing soil element composition. These results suggest significant fluctuations in the extractable concentrations of specific mineral elements in these soils, implying potential future variations in soil element composition as well as the loss of total element concentrations/contents in semi-arid Mediterranean ecosystems due to increasing warming. Therefore, these findings enhance our ability to predict ecosystem management strategies and mitigate the observed negative impacts on plant-soil systems and water quality in the context of climate change.

β-Hydroxybutyrate enhances astrocyte glutamate uptake through EAAT1 expression regulation

β-Hydroxybutyrate (BHB) has been reported to exert neuroprotective functions and is considered a promising treatment for neurodegenerative diseases such as Parkinson's and Alzheimer's. Numerous studies have revealed BHB's multifaceted roles, including anti-senescence, anti-oxidative, and anti-inflammatory activities. However, the underlying mechanisms warrant further investigation. Astrocytes, the most abundant glial cells in the central nervous system, play a pivotal role in the development and progression of neurodegenerative diseases. While BHB is known to alter neuronal metabolism and function, its effects on astrocytes remain poorly understood. In this study, we conducted transcriptome sequencing analysis to identify differentially expressed genes induced by BHB in astrocytes and found that the gene Solute carrier family 1 member 3 (Slc1a3), encoding the glutamate transporter EAAT1, was significantly upregulated by BHB treatment. Cellular and animal-based experiments confirmed an increase in EAAT1 protein expression in primary astrocytes and the hippocampus of mice treated with BHB. This upregulation may be due to the activation of the Ca2+/CAMKII pathway by BHB. Furthermore, BHB improved astrocytes' glutamate uptake and partially restored neuronal viability impaired by glutamate-induced excitotoxicity when astrocytes were functionalized. Our results suggest that BHB may alleviate neuronal damage caused by excessive glutamate by enhancing the glutamate absorption and uptake capacity of astrocytes. This study proposes a novel mechanism for the neuroprotective effects of BHB and reinforces its beneficial impact on the central nervous system (CNS).

Beta-adrenergic agonism protects mitochondrial metabolism in the pancreatectomised rat heart

The diabetic heart is characterised by functional, morphological and metabolic alterations predisposing it to contractile failure. Chronic sympathetic activation is a feature of the pathogenesis of heart failure, however the type 1 diabetic heart shows desensitisation to β-adrenergic stimulation. Here, we sought to understand the impact of repeated isoprenaline-mediated β-stimulation upon cardiac mitochondrial respiratory capacity and substrate metabolism in the 90% pancreatectomy (Px) rat model of type 1 diabetes. We hypothesised these hearts would be relatively protected against the metabolic impact of stress-induced cardiomyopathy. We found that individually both Px and isoprenaline suppressed cardiac mitochondrial respiration, but that this was preserved in Px rats receiving isoprenaline. Px and isoprenaline had contrasting effects on cardiac substrate metabolism, with increased reliance upon cardiac fatty acid oxidation capacity and altered ketone metabolism in the hearts of Px rats, but enhanced capacity for glucose uptake and metabolism in isoprenaline-treated rats. Moreover, Px rats were protected against isoprenaline-induced mortality, whilst isoprenaline elevated cGMP and protected myocardial energetic status in Px rat hearts. Our work suggests that adrenergic stimulation may be protective in the type 1 diabetic heart, and underlines the importance of studying pathological features in combination when modeling complex disease in rodents.

Insights into the Enantiomeric Uptake, Translocation, and Distribution of Triazole Chiral Pesticide Mefentrifluconazole in Wheat (Triticum aestivum L.).

The uptake, translocation, and accumulation of mefentrifluconazole (MFZ), an innovative chiral triazole fungicide, in plants at the enantiomeric level are still unclear. Herein, we investigated the patterns and mechanisms of enantiomeric uptake, bioaccumulation, and translocation through several experiments. Rac-MFZ shows the strongest uptake and bioaccumulation capacity in wheat compared with its enantiomers, while S-(+)-MFZ has the highest translocation potential. Molecular docking provided evidence of the stronger translocation ability of S-(+)-MFZ than R-(-)-MFZ. Split-root experiments showed that MFZ and its enantiomers could undergo long-distance transport within the wheat. Active transport or facilitated and simple diffusion may be involved in the wheat uptake of MFZ. The limited acropetal translocation capability of MFZ may be attributed to the dominant uptake pathway of apoplastic. The concentrations of Rac-MFZ in different subcellular fractions varied greatly. In summary, this study provides novel insights for further understanding the behaviors of MFZ and its enantiomers in plants.

Mind the Gap: The Role of Mass Transfer in Shaped Nanoporous Adsorbents for Carbon Dioxide Capture.

Adsorptive separations by nanoporous materials are major industrial processes. The industrial importance of solid adsorbents is only expected to grow due to the increased focus on carbon dioxide capture technology and energy-efficient separations. To evaluate the performance of an adsorbent and design a separation process, the adsorption thermodynamics and kinetics must be known. However, although diffusion kinetics determine the maximum production rate in any adsorption-based separation, this aspect has received less attention due to the challenges associated with conducting diffusion measurements. These challenges are exacerbated in the study of shaped adsorbents due to the presence of porosity at different length scales. As a result, adsorbent selection typically relies mainly on adsorption properties at equilibrium, i.e., uptake capacity, selectivity and adsorption enthalpy. In this Perspective, based on an extensive literature review on mass transfer of CO2 in nanoporous adsorbents, we discuss the importance and limitations of measuring diffusion in nanoporous materials, from the powder form to the adsorption bed, considering the nature of the process, i.e., equilibrium-based or kinetic-based separations. By highlighting the lack of and discrepancies between published diffusivity data in the context of CO2 capture, we discuss future challenges and opportunities in studying mass transfer across scales in adsorption-based separations.

Development of a Multiparticulate Metal-Organic Framework/Textile Fiber Swatch.

The versatility of metal-organic frameworks (MOFs) has led to groundbreaking applications in a wide variety of fields, especially in the areas of energy, environment, and sustainability. For example, MOFs can be designed for high uptake of toxic gases and pollutants, such as CO2, NH3, and SO2, but designing a single MOF that shows tangible uptake for all of these gases is challenging due to the differences in the chemical and physical properties of these molecules. To this end, integrating multiple MOFs onto textile fibers and crafting various structures have emerged as pivotal developments, enhancing framework durability and usability. MOF composites prepared on readily available textile fibers offer the flexibility essential for critical applications, including heterogeneous catalysis, chemical sensing, toxic gas adsorption, and drug delivery, while preserving the unique characteristics of MOFs. This study introduces a scalable and adaptable method for seamlessly embedding multiple high-performing MOFs onto a single textile fiber using a dip-coating method. We explored the uptake capacity of these multi-MOF composites for CO2, NH3, and SO2 and observed a performance similar to that of traditional powdered materials. Along with harmful gas adsorption, we also have evaluated the permeation and reactivity of these MOF/textile composites toward chemical warfare agents (CWAs) like GD (soman), HD (mustard gas), and VX. In combination, these results demonstrate a fundamental advancement toward establishing a consistent strategy for the hydrolysis of nerve agents in real-world scenarios. This approach can substantially increase the protection toward CWAs and enhance the effectiveness of protective equipment such as fabrics for protective garments. This dip-coating method for the integration of multiple MOFs on a single textile fiber unlocks a wealth of possibilities and paves the way for future innovations in the deployment of MOF-based composites.

β-Ketoenamine-linked covalent organic framework for efficient iodine capture.

Exploring the materials that effectively capture radioactive iodine is crucial in managing nuclear waste produced from nuclear power plants. In this study, a β-ketoenamine-linked covalent organic framework (bCOF) is reported as an effective adsorbent to capture iodine from both vapor and solution. The bCOF's high porosity and heteroatom-rich skeleton offer notable iodine vapor uptake capacity of up to 2.51 g g-1 at 75 °C under ambient pressure. Furthermore, after five consecutive adsorption-desorption cycles, the bCOF demonstrates high reusability performance with significant iodine vapor capacity retention. The adsorption mechanism was also investigated using various ex situ structural characterization techniques, and these mechanistic studies revealed the existence of a strong chemical interaction between the bCOF and iodine. The bCOF also showed good iodine uptake performance of up to 512 mg g-1 in cyclohexane with high removal efficiencies. The bCOF's performance in adsorbing iodine from both vapor and solution makes it a promising material to be used as an effective adsorbent in capturing radioactive iodine emissions from nuclear power plants.

Heavy metals biosorption in unary, binary, and ternary systems onto bacteria in a moving bed biofilm reactor

Toxic and heavy metals cause direct and indirect damage to the environment and ultimately to humans. This study involved the isolation of indigenous bacteria from heavy metal-contaminated environments that have the ability to bioabsorb heavy metals such as cadmium, nickel, and lead. The bioabsorption process was optimized by varying parameters such as temperature, metal concentration, number of bacteria, pH, and more. The bacterial isolates were investigated in terms of morphology, biochemistry, and phylogeny, with 12 strains chosen in the initial stage and one strain chosen in the final stage. It should be remembered that the metal uptake capacity of all isolates was approximately calculated. A box and reactor were designed to house these optimized microorganisms. Based on biochemical, morphological, and molecular results, the isolated strain was found to be closely related to the Bacillus genus. In the first five steps of testing, the ideal pH for removing lead alone, lead with cadmium, lead with nickel, and lead ternary (with cadmium and nickel) by Bacillus bacteria was found to be 7, 6, 5.5, and 6.5, respectively. The absorption efficiencies for single lead (unary), lead together with nickel, cadmium (binary), and ternary (lead with cadmium and nickel) were found to be 0.36, 0.25, 0.22, and 0.21 mmol/g, respectively. The ideal temperature for lead removal was around 30 °C. The adsorption isotherm for each lead metal in different states was found to be similar to the Langmuir isotherm, indicating that the surface absorption process is a single-layer process. The kinetics of the process follow the second-order kinetic model. The amount of Bacillus bacteria biomass obtained during this process was approximately 1.5 g per liter.

Exhaled Anesthetic Xenon Regeneration by Gas Separation Using a Metal-Organic Framework with Sorbent-Sorbate Induced-Fit.

Noble gas xenon (Xe) is an excellent anesthetic gas, but its rarity, high cost and constrained production prohibits wide use in medicine. Here, we have developed a closed-circuit anesthetic Xe recovery and reusage process with highly effective CO2-specific adsorbent CUPMOF-5 that is promising to solve the anesthetic Xe supply problem. CUPMOF-5 possesses spacious cage cavities interconnected in four directions by confinement throat apertures of ~3.4 Å, which makes it an ideal molecular sieving of CO2 from Xe, O2, N2 with the benchmark selectivity and high uptake capacity of CO2. In situ single-crystal X-ray diffraction (SCXRD) and computational simulation solidly revealed the vital sieving role of the confined throat and the sorbent-sorbate induced-fit strengthening binding interaction to CO2. CUPMOF-5 can remove 5 % CO2 even from actual moist exhaled anesthetic gases, and achieves the highest Xe recovery rate (99.8 %) so far, as verified by breakthrough experiments. This endows CUPMOF-5 great potential for the on-line CO2 removal and Xe recovery from anesthetic closed-circuits.

Exhaled Anesthetic Xenon Regeneration by Gas Separation Using a Metal–Organic Framework with Sorbent‐Sorbate Induced‐Fit

AbstractNoble gas xenon (Xe) is an excellent anesthetic gas, but its rarity, high cost and constrained production prohibits wide use in medicine. Here, we have developed a closed‐circuit anesthetic Xe recovery and reusage process with highly effective CO2‐specific adsorbent CUPMOF‐5 that is promising to solve the anesthetic Xe supply problem. CUPMOF‐5 possesses spacious cage cavities interconnected in four directions by confinement throat apertures of ~3.4 Å, which makes it an ideal molecular sieving of CO2 from Xe, O2, N2 with the benchmark selectivity and high uptake capacity of CO2. In situ single‐crystal X‐ray diffraction (SCXRD) and computational simulation solidly revealed the vital sieving role of the confined throat and the sorbent‐sorbate induced‐fit strengthening binding interaction to CO2. CUPMOF‐5 can remove 5 % CO2 even from actual moist exhaled anesthetic gases, and achieves the highest Xe recovery rate (99.8 %) so far, as verified by breakthrough experiments. This endows CUPMOF‐5 great potential for the on‐line CO2 removal and Xe recovery from anesthetic closed‐circuits.

Ultrastable Carboxyl-Functionalized Pore-Space-Partitioned Metal-Organic Frameworks for Gas Separation.

Isoreticular chemistry, which enables property optimization by changing compositions without changing topology, is a powerful synthetic strategy. One of the biggest challenges facing isoreticular chemistry is to extend it to ligands with strongly coordinating substituent groups such as unbound -COOH, because competitive interactions between such groups and metal ions can derail isoreticular chemistry. It is even more challenging to have an isoreticular series of carboxyl-functionalized MOFs capable of encompassing chemically disparate metal ions. Here, with the simultaneous introduction of carboxyl functionalization and pore space partition, a family of carboxyl-functionalized materials is developed in diverse compositions from homometallic Cr3+ and Ni2+ to heterometallic Co2+/V3+, Ni2+/V3+, Co2+/In3+, Co2+/Ni2+. Cr-MOFs remain highly crystalline in boiling water. Unprecedentedly, one Cr-MOF can withstand the treatment cycle with 10m NaOH and 12m HCl, allowing reversible inter-conversion between unbound -COOH acid form and -COO- base form. These materials exhibit excellent sorption properties such as high uptake capacity for CO2 (100.2 cm3g-1) and hydrocarbon gases (e.g., 142.1 cm3g-1 for C2H2, 110.5 cm3g-1 for C2H4) at 1 bar and 298K, high benzene/cyclohexane selectivity (up to ≈40), and promising separation performance for gas mixtures such as C2H2/CO2 and C2H2/C2H4.

Immunocytochemical evaluation of aquaporins and cell wall components and their influence on foliar water uptake in Andean Melastomataceae.

Andean ecosystems are characterized by high humidity, mainly from rain and fog events. Because of differences in altitude two Andean ecosystems - sub-Andean forest and Páramo -face different environmental pressures that affect leaf anatomy and cell wall composition and, consequently, species foliar water uptake (FWU) capacity. Here, FWU capacity of eight species in the Melastomataceae was evaluated and found to be related to proportions of cell wall components and aquaporins in the two ecosystems. Cellulose was labelled with Calcofluor white, and aquaporin and pectins were labelled with monoclonal antibodies. There were differences in plant FWU capacity in both ecosystems, with higher FWU capacity in sub-Andean forest species than in Páramo forest species. Cell wall components were positively related to FWU, with increased FWU related to pectin and aquaporin content of the plasma membrane. Differences in water availability in the two analysed environments led to differences in FWU capacity that are associated with leaf anatomical traits and cell wall composition. In these two environments, plants with similar traits are selected to respond to given environmental pressures. Traits that favour FWU in sub-Andean forest species may lead to further advances of these species in this environments.

Probing the Distribution and Mobility of Aminopolymers after Multiple Sorption-Regeneration Cycles: Neutron Scattering Studies.

Solid-supported amines are effective CO2 adsorbents capable of capturing CO2 from flue gas streams (10-15 vol % CO2) and from ultradilute streams, such as ambient air (∼400 ppm CO2). Amine sorbents have demonstrated promising performance (e.g., high CO2 uptake and uptake rates) with stable characteristics under repeated, idealized thermal swing conditions, enabling multicycle application. Literature studies suggest that solid-supported amines such as PEI/SBA-15 generally exhibit slowly reducing CO2 uptake rates or capacities over repeated thermal swing capture-regeneration cycles under simulated DAC conditions. While there are experimental reports describing changes in supported amine mass, degradation of amine sites, and changes in support structures over cycling, there is limited knowledge about the structure and mobility of the amine domains in the support pores over extended use. Furthermore, little is known about the effects of H2O on cyclic applications of PEI/SBA-15 despite the inevitable presence of H2O in ambient air. Here, we present a series of neutron scattering studies exploring the distribution and mobility of PEI in mesoporous silica SBA-15 as a function of thermal cycling and cyclic conditions. Small-angle neutron scattering (SANS) and quasielastic neutron scattering (QENS) are used to study the amine and H2O distributions and amine mobility, respectively. Applying repeated thermal swings under dry conditions leads to the thorough removal of water from the sorbent, causing thinner and more rigid wall-coating PEI layers that eventually lead to slower CO2 uptake rates. On the other hand, wet cyclic conditions led to the sorption of atmospheric water at the wall-PEI interfaces. When PEI remains hydrated, the amine distribution (i.e., wall-coating PEI layer thickness) is retained over cycling, while lubrication effects of water yield improved PEI mobility, in turn leading to faster CO2 uptake rates.

Cu-based metal-organic framework with dual open metal sites for efficient separation of CO2 from flue gas

Excessive carbon dioxide (CO2) emissions from flue gases intensify the greenhouse effect. Exploring porous adsorbents with high CO2/N2 selectivity is of great significance to reducing the CO2 content in flue gases. Herein, we report a novel PtS-type metal-organic framework (MOFs), termed ZSTU-21, with narrow pore size and excellent CO2/N2 separation performance with dual open copper sites. At 298 K, ZSTU-21 exhibits a CO2 uptake capacity of 62 cm3 g−1 and a high selectivity of 105 for CO2/N2 (CO2/N2 = 15/85, v/v). Multicomponent adsorption breakthrough experiments further verified the superior performance of ZSTU-21 MOF in CO2/N2 separation. Moreover, the synthesis of ZSTU-21 MOF can be carried out under mild experimental conditions at room temperature, making the process simple and cost-effective, thus laying a solid foundation for its widespread application in CO2/N2 separation.

N-Heteroatom Engineered Nonporous Amorphous Self-Assembled Coordination Cages for Capture and Storage of Iodine.

Radioactive iodine isotopes from nuclear-related activities, present substantial risks to human health and the environment. Developing effective materials for the capture and storage of these hazardous molecules is paramount. Traditionally, nonporous solids were historically considered ineffective for adsorbing target species. In this study, we investigate the potential of four nonporous, amorphous, self-assembled coordination cages (C1, C2, C3, and C4) featuring varying numbers of nitrogen atoms within the core (pyridyl/triazine unit) and specific cavity sizes for iodine adsorption. These coordination cages demonstrate remarkable adsorption abilities for iodine in both vapor and solution phases, facilitated by enhanced electron-pair interactions. The cages exhibit high uptake capacities of up to 3.16 g g-1 at 75 °C, the highest among metal-organic cages and up to 434.29 mg g-1 in solution, highlighting the efficiency of these materials across different phases. Even at ambient temperature, they show significant iodine capture efficiency, with a maximum value of 1.5 g g-1. Furthermore, these robust materials can be recycled, enduring at least five reusable cycles without apparent fatigue. Overall, our findings present a "N-heteroatom engineering" approach for the development of recyclable amorphous containers for the capture and storage of iodine, contributing to the mitigation of nuclear-related risks.