Water Adsorption Research Articles

Small Rotations, Big Effects: Lessons from Water Adsorption in NU-1000

Small Rotations, Big Effects: Lessons from Water Adsorption in NU-1000

New insights in large-pores mesoporous silica microspheres for hemostatic application

Hemorrhages are still considered a common cause of death and despite the availability of different hemostatic agents it is still necessary to develop more effective hemostats for bleeding managements in emergency situations. Herein, large-pores mesoporous silica microspheres (MSM) were synthesized, and their surface was modified to enrich the hydroxyls population with the aim of achieving a material with enhanced water adsorption capacity and high hemostatic ability. The success of surface modification was investigated by Fourier Transform Infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA), which confirmed the increase in the amount of surface hydroxyl groups. A hemolysis assay as well as a clotting test were carried out to evaluate the hemocompatibility and hemostatic ability, respectively. It was found that the modified material presented the lowest hemolytic ratio and the lowest clotting time. The novelty of the paper is mainly due to the coupling of the hemostatic ability test with the adsorption microcalorimetry of water. In fact, being the water adsorption on the material surface a crucial factor in the hemostatic activity, microcalorimetry was used for the first time to study the adsorption of water and estimate its heat of adsorption. The data obtained showed that the modified MSM presents a surface able to adsorb a higher amount of water, compared to the pristine MSM, with a low molar heat of adsorption (about 35 kJ/mol), which renders the modified MSM presented in the present study an excellent candidate for producing novel hemostats.Graphical

Metabolomic profiling of paper board sludge biochar for agricultural use.

The pulp and paperboard industries are the major industrial sector that consumes significant amounts of fresh water and generates large volumes of wastewater. The treatment of this wastewater resulted in the production of a substantial amount of sludge, which posed serious environmental challenges. This study explored a sustainable solution by converting PBS into biochar through slow pyrolysis of temperatures up to ≤ 500°C, offering an alternative approach to waste management and resource conservation. The physicochemical parameters of paper board sludge biochar (PBSB) exhibited a neutral pH of 7.49, electrical conductivity of 0.09 dS m-1, organic carbon of 38.12% and CaCO3 of 24.5%. Proximate analysis of PBSB revealed an increased fixed carbon of 76.43%, total organic carbon (TOC) of 7.13%, and reduced volatile matter and moisture levels. The TGA analysis of the dried paperboard sludge sample showed a 20% mass reduction when heated to 350°C. During this process, more than 90% of the volatile components were removed.. The micro nutrients viz., Fe 5.06mg L-1, Mn 419.3mg L-1, Cu 26.3mg L-1, and Zn 66.1mg L-1 contents were observed in PBSB. FT-IR analysis identified the presence of various carbon-containing functional groups, including C-Cl, C-N, C-C, H-C = O, C-H, and -C≡C-H, indicating substantial chemical transformations during pyrolysis. SEM-EDX analysis revealed that PBSB has fine particle size and a coarse fluffy spongy porous structure ideal for water adsorption. Elemental analysis (XRD) showed high carbon and oxygen content with significant amounts of aluminosilicates, carbonates, and nutrients like phosphorus and potassium, suggesting PBSB as a potential slow-release fertilizer. This research highlights the potential of biochar derived from paperboard waste as a sustainable solution for waste management and resource recovery.

Insight the essential role of manganese impurity to the initial hydration of Mn‐doped C4AF at the atomic level

AbstractThe growing focus on reducing CO₂ emissions has promoted the use of alternative raw materials in cement production. Most heavy metal ions from these materials are preferentially incorporated into tetracalcium aluminoferrite (C₄AF), making it important to understand the effect of this incorporation on C₄AF hydration. In this work, we examined the hydration properties of manganese (Mn)‐doped C₄AF by combining well‐defined density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. The results indicate that Mn doping stabilizes the Mn–O octahedral structure, reducing charge transfer between water molecules and the surface. This change lowers adsorption energy and interfacial bond strength, weakening the potential for dissociative water adsorption. Mn doping reduces the initial hydration reaction rate of C₄AF, with the following hierarchy of reaction rates observed: pure C₄AF > Mn‐doped C₄AF surface > Mn‐doped C₄AF interphase. The hydrogen bonding density at the interface becomes localized upon Mn addition, reducing charge transfer between the water and the surface. Mn near the interface further delays the reaction by anchoring water molecules and hydroxyl groups. These findings provide valuable insights into the early hydration of Mn‐doped C₄AF.

Impact of Water Saturation on the Anisotropic Elastic Moduli of a Gas Shale

Abstract How water saturation affects elastic properties is particularly important for analyses of gas shales in unconventional reservoirs, but experimental data in defined partially saturated conditions are rare. We show that the elastic moduli of a gas shale vary significantly with water saturation whereas the static anisotropy does not. A series of repeated hydrostatic compression were carried out on a gas shale specimen at various water saturation states to determine the elastic moduli ( $${E}_{\text{v}}$$ E v and $${E}_{\text{h}}$$ E h ) as a function of degree of saturation ( $${S}_{\text{r}}$$ S r ). The elastic moduli were calculated from the reversible stress–strain curves after repeating confining pressure cycles. We found that, while water saturation increases, the elastic moduli peak at intermediate degree of saturation and then decreases to the minimum value at quasi-saturation. This evolution of the elastic moduli with degree of saturation may be explained by unifying two water retention mechanisms, adsorption and capillarity, that have overall competing effects on the stiffness. It is believed that adsorption softens the gas shale by reducing the friction of the load-bearing clay matrix, while capillary menisci stiffen the gas shale by providing stabilizing forces. The Young’s modulus anisotropy ( $${E}_{\text{h}}/{E}_{\text{v}}$$ E h / E v ) did not show appreciable change with degree of saturation. Confining pressure seems to be a more important control on changes in the static anisotropy. Analyzing the volumetric behavior of gas shales in unconventional reservoirs should take into account the degree of saturation dependency. Extrapolating the experimental results to in-situ conditions must be done with great care.

Hydrophobic post-functionalization of a water instable bioMOF: Effect on CO2 and water adsorption

Hydrophobic post-functionalization of a water instable bioMOF: Effect on CO2 and water adsorption

A Microstructural Insight into the Hygrothermal Behaviour of Unstabilised and Cement Stabilised Compressed Earthen Bricks Exposed to High Temperatures

Earthen materials has received a lot of attention as a sustainable building material over the past few decades because of its eco-friendliness. As consequence of this renewed interest, numerous works have been recently developed on earthen materials, mostly with a focus on their mechanical behaviour. Conversely, there is still a significant gap in the literature on the understanding of the fire behaviour of earthen materials. Only a handful of studies has dealt with this subject and a systematic analysis on the causes of thermal instabilities in earth materials at high temperatures is still missing from the literature. The role played by the mineralogy of the earth materials on these thermal instabilities is still poorly understood and it requires further investigation. To fill these gaps, the present study presents the results from both mineralogical and hygrothermal tests performed on earth samples, which were either left unstabilised and compacted at 50 MPa or stabilised with cement and compacted at the optimum standard Proctor. Interestingly, unstabilised earthen samples exhibited thermal instabilities when exposed to high temperatures. To investigate deeper into the mineralogical causes of such thermal instabilities, samples were either equalised at the ambient temperature of about 25 °C or exposed at the high temperature of 350 °C before being subjected to thermogravimetric and differential scanning calorimetry (TG-DSC) tests, Fourier Transform Infrared (FTIR) spectroscopy tests, isothermal adsorption-desorption tests, and nitrogen gas permeability tests. Results show that cement stabilisation induced the formation of fresh the calcium-silicate-hydrate (C-S-H) and calcium-aluminate-hydrate (C-A-H) gels while reducing the water adsorption capacity. Both effects have rendered the material less prone to thermal instabilities compared to the unstabilised material. The main mineralogical and moisture-related changes influencing thermal and fire behavior might not be well captured by traditional studies. Though lacking in information to perform a thorough study, they do provide initial indications of possible internal alterations within the materials.

Evaluation of the onset voltage of water adsorption on Pt(111) surface using density functional theory/implicit model calculations

Evaluation of the onset voltage of water adsorption on Pt(111) surface using density functional theory/implicit model calculations

Synthesis and Characterization of Sodium Alginate Spheres Functionalized with Dicarboxylic Acids for Copper Removal in Aqueous Media

AbstractNew polymeric spheres of sodium alginate (AlgNa) containing dicarboxylic acids—maleic acid (MA) and oxalic acid (OA)—were developed for adsorption of copper metal from water. Water adsorption capacity, elementary composition, structural, morphological, vibrational, and thermal properties were characterized by scanning electron microscopy (SEM), intumescence degree (IG), X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, and differential scanning calorimetry. SEM data revealed that functionalization with dicarboxylic acids affects the morphology and surface of the AlgNa matrix. Sample containing MA (0.35 ± 0.004 g) absorbs more water than the OA sphere (0.28 ± 0.007 g). XRD patterns showed that the AlgNa–MA and AlgNa samples exhibit an amorphous nature, whereas the AlgNa–OA sample has a partially crystalline phase. Adsorption experiments were conducted to analyze whether the synthesized spheres could be optimized to reach the best performance in copper adsorption. The adsorbents were most efficient at the highest dosage used (250 mg), corresponding to removal percentages of 84.54 ± 3.97% (AlgNa), 94.21 ± 3.04% (AlgNa–MA), and 84.22 ± 3.39% (AlgNa–OA). The energy‐dispersive X‐ray spectroscopy maps validated the incorporation of Cu2+ ions on the surface of the adsorbents. Kinetic and isotherm assays confirmed the highest efficiency of AlgNa–MA spheres.

Characterization and antioxidant activity of differentiated fractionation lignin from corn stover.

Lignin contains many chemical functional groups with multiple biological activities. However, the heterogeneity of lignin such as complex structure and high polydispersity, and poor dissolution performance hinders its value-added application. In this study, it was found that there was a significant difference in the solubility of the chemical components of corn stover alkali-extracted lignin-carbohydrate complex (CSALCC) in a 0.6 M NaHCO3 solution. Herein, CSALCC was fractionated using a 0.6 M NaHCO3 solution, hot water, acid precipitation, and macroporous adsorption resin D101 column chromatography to afford fraction F1-1, F2, and F3-1. To demonstrate the improvement in composition, water solubility and antioxidant activity of the fractions. The characterization techniques UV, FTIR, NMR, TGA, SDS-PAGE and GPC were employed. Antioxidant activities were evaluated by ABTS, ORAC and ferric reducing power assay. F1-1 consists mainly of hemicellulose and is soluble in deionized water. F2 is a more water-soluble lignin than CSALCC, which is conducive to the development of value-added products of lignin in aqueous systems. F3-1 was acidic-soluble lignin with the highest total polyphenol content of all the fractions, and exhibited higher water solubility, antioxidant properties and UV absorption. F3-1 may have potential application in cosmetics, pharmaceuticals, the food processing field.

Amine‐Functionalized Triazolate‐Based Metal–Organic Frameworks for Enhanced Diluted CO2 Capture Performance

AbstractEfficient CO2 capture at concentrations between 400–2000 ppm is essential for maintaining air quality in a habitable environment and advancing carbon capture technologies. This study introduces NICS‐24 (National Institute of Chemistry Structures No. 24), a Zn‐oxalate 3,5‐diamino‐1,2,4‐triazolate framework with two distinct square‐shaped channels, designed to enhance CO2 capture at indoor‐relevant concentrations. NICS‐24 exhibits a CO2 uptake of 0.7 mmol/g at 2 mbar and 25 °C, significantly outperforming the compositionally related Zn‐oxalate 1,2,4‐triazolate – CALF‐20 (0.17 mmol/g). Improved performance is attributed to amino‐functions that enhance CO2 binding and enable superior selectivity over N2 and O2, achieving 8‐fold and 30‐fold improvements, respectively, in simulated CO2/N2 and CO2/O2 atmospheric ratios. In humid environments, NICS‐24 retained structural integrity but exhibited an 85 % reduction in CO2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO2 due to strong hydrogen‐bonding interactions within the framework. Gained understanding of the interaction between CO2 and H2O within the MOF framework could guide the modification via rational design with improved performance under real‐world conditions.

Amplifying Electron-Donor Signal of the "Water Gate" Enabled Low Detection Ability of a Field-Effect Transistor-Based Humidity Sensor.

Low humidity detection down to the parts per million level is urgently demanded in various industrial applications. The hardly detected tiny electrical signal variations caused by a very small amount of water adsorption are one of the intrinsic reasons that restrain the detection limit of the humidity sensors. Herein, a carbon-based field-effect transistor (FET) humidity sensor utilizing adsorbed water as the dual function of a sensing gate and analyte was proposed. Owing to the electron donor property of the "water gate" that can serve as a negative voltage exerted on the dielectric layer, the electrical conductivity of the FET's channel can be significantly modulated, therefore realizing signal amplification. The proposed sensor presents a detection limit of lower than 1% RH. Besides, the fabricated sensors show good batch consistency (response deviation of 0.5%), repeatability, long-term stability, and acceptable hysteresis (6.3% relative humidity (RH)) in humidity detection. We hope that our work can offer a novel strategy for the application and integration of low humidity detection from the device aspect rather than sensing materials synthesis.

Applications of MOF-Based Nanocomposites in Heat Exchangers: Innovations, Challenges, and Future Directions

Metal–organic frameworks (MOFs) have garnered significant attention in recent years for their potential to revolutionize heat exchanger performance, thanks to their high surface area, tunable porosity, and exceptional adsorption capabilities. This review focuses on the integration of MOFs into heat exchangers to enhance heat transfer efficiency, improve moisture management, and reduce energy consumption in Heating, Ventilation and Air Conditioning (HVAC) and related systems. Recent studies demonstrate that MOF-based coatings can outperform traditional materials like silica gel, achieving superior water adsorption and desorption rates, which is crucial for applications in air conditioning and dehumidification. Innovations in synthesis techniques, such as microwave-assisted and surface functionalization methods, have enabled more cost-effective and scalable production of MOFs, while also enhancing their thermal stability and mechanical strength. However, challenges related to the high costs of MOF synthesis, stability under industrial conditions, and large-scale integration remain significant barriers. Future developments in hybrid nanocomposites and collaborative efforts between academia and industry will be key to advancing the practical adoption of MOFs in heat exchanger technologies. This review aims to provide a comprehensive understanding of current advancements, challenges, and opportunities, with the goal of guiding future research toward more sustainable and efficient thermal management solutions.

Physically cross-linked cellulose nanofiber (LCNF/CNF) hydrogels: impact of the composition on mechanical and swelling properties

Lignocellulose nanofibers (LCNFs) are highly regarded for their ability to significantly enhance the rigidity of formed structures. When integrated into cellulose nanofiber (CNF) hydrogels, they hold substantial promise in augmenting mechanical strength, as well as improving adsorption capacity. Herein, the preparation of hydrogels from an aqueous suspension of CNFs and LCNFs extracted from eucalyptus cellulose pulp through a homogenization process is outlined. Suspensions of different concentrations were prepared to assess the influence of lignin and nanofiber content on the properties of the hydrogels. The hydrogels cellulose nanofibers (HCNF) and lignocellulose nanofibers (HLCNF) were formed through a freeze–thaw process, revealing an enhancement in rigidity with increasing nanofiber concentration. DFT (density functional theory) calculations illustrated the cross-linking mechanism between cellulose chains induced by the crystallization of water molecules, thus, corroborating the postulated hydrogel formation mechanism. Microstructural analysis revealed honeycomb-shaped matrices in longitudinal sections, with HLCNF hydrogels presenting less smooth walls. Studies on water adsorption capacity showed rapid swelling in both hydrogels, correlated with the nanofiber content reaching 8750% and 5500% for HLCNF and HCNF, respectively. HLCNF hydrogels exhibited higher adsorption capacity due to the influence of lignin on cross-linking rates. Mechanical compression tests demonstrated exceptional resilience in all hydrogels. Despite having a lower cross-linking density compared to hydrogels made from 2 wt.% cellulose nanofibers, hydrogels composed of 2 wt.% lignocellulose nanofibers exhibited a Young’s modulus of 2.83 kPa. This underscores the superior mechanical properties of lignin-based hydrogels, highlighting the effect of lignin on the hydrogel matrix.

Creating Dual Active Sites in Ru-doped FeMn-MOF-74 for Efficient Overall Water Splitting.

The design of well-engineered bifunctional electrocatalysts is crucial for achieving durable and efficient performance in overall water splitting. In this study, Ru-doped FeMn-MOF-74 itself has Ru sites and generates FeMnOOH under catalytic conditions, forming dual active sites for overall water splitting. Density functional theory (DFT) calculations demonstrate that the Ru dopants exhibit optimized binding strength for H* and enhanced hydrogen evolution reaction (HER) performance. Moreover, the Mn sites within FeMnOOH lower the energy barrier for the rate-determining step (from O* to OOH*), serving as the active centre for oxygen evolution reaction (OER). The incorporation of Ru significantly improves the electron transfer properties of FeMn-MOF-74 and enhances its water adsorption capacity, synergistically boosting its bifunctional activity. This strategy of designing dual active sites provides new insights into the development of bifunctional metal-organic frameworks (MOFs) for efficient overall water splitting.

Separation of Ethanol–Water Azeotrope Using Waste Carrageenan Filter‐Cake Adsorbent

ABSTRACTThe final step in the downstream processing of bioethanol is typically the removal of water from the ethanol–water azeotrope (95.6 wt.% ethanol) to obtain fuel‐grade ethanol (> 99 wt.%). This can be done by various techniques including distillation (azeotropic or extractive), membrane‐based separation, and adsorption using molecular sieves or bio‐based adsorbents. In this work, a waste by‐product of carrageenan production is studied for its efficacy as water adsorbent. This waste carrageenan filter‐cake (CFC) material is primarily composed of organics (22 wt.% cellulose and carrageenan) and ash (78 wt.% perlite) as inferred from the proximate analysis. The functional groups present in the material were identified by FTIR analyses, and the surface morphology was checked by FESEM. Liquid phase water adsorption isotherms at 30°C, 40°C, and 50°C were established and were found to be adequately described by both Langmuir (R2 = 0.93 to 0.97) and Brouers‐Sotolongo (R2 = 0.96 to 0.97) models. An enthalpy change of adsorption of about −17 kJ/mol was computed through the van't Hoff equation. An azeotropic mixture (95.6 wt.% ethanol) was successfully purified to above 99.2 wt.% ethanol in a CFC‐packed column. The CFC adsorbent was used in three adsorption–desorption cycles without much loss in capacity. Moreover, the Thomas model adequately described the breakthrough curves.

Theoretical Insights into Methanol Electro-Oxidation on NiPd Nanoelectrocatalysts: Investigating the Carbonate–Palladium Oxide Pathway and the Role of Water and OH Adsorption

We conducted a theoretical and experimental study on the electro-oxidation of methanol (MOR) on NixPdy nanoparticles. The results are presented in terms of kinetic parameters, surface concentrations, and peak currents, showing significant differences between three main compositions: Ni3Pd1, Ni1Pd1, and Ni1Pd3. The kinetic mechanism adopted for accounting the linear voltammetry experiments performed follows the carbonate–palladium oxide pathway of the MOR. Numerical simulations of the kinetic equations, fitted to experimental data obtained at varying methanol concentrations, allowed us to distinguish the adsorption contributions of methanol, water, and OH ions from the nonlinear contribution associated with palladium oxide and carbon dioxide production. The synergistic effects of Ni:Pd nanoalloys on the MOR were then assessed by analyzing the behavior and tendencies of the reaction rate constants for different bulk methanol concentrations. Our results suggest that a higher Pd content favors more efficient oxidation mechanisms by reducing the formation of intermediate products that cause surface poisoning, such as CO, carbonates, or palladium oxide. However, as the proportion of Ni increases, an increase in the concentration of adsorbed OH is observed, which dominates the blocking of active sites even greater than the palladium oxide blocking.

Hydrogen Spillover Enabled by Edge Dislocations for Efficient Hydrogen Evolution

AbstractDesigning an efficient alkaline hydrogen evolution reaction (HER) catalyst requires enhanced hydrogen adsorption to facilitate water dissociation while noting that this would be detrimental to H2 desorption. Although hydrogen spillover‐assisted HER has been emerging as a promising strategy due to separated active sites for water dissociation and hydrogen formation enabled by heterogeneous catalysts, interfacial charge accumulation, and strong interfacial proton adsorption would hinder proton transfer due to a high energy barrier. Herein, a novel strategy to realize hydrogen spillover‐assisted HER enabled by edge dislocations of Mo2C catalyst is presented. The coupled tensile‐compressive strain regions induced by edge dislocations serve as nano‐reactors for HER. The Volmer process is greatly enhanced by strong water adsorption and efficient *H2O dissociation in the tensile regions, meantime the generated *H rapidly transfers to the compressive regions for easy hydrogen molecule release. As a result, the edge dislocation‐rich catalyst achieves a low overpotential of only 61 and 179 mV at 10 and 300 mA cm−2, showcasing a new way to apply hydrogen spillover in single‐phase catalysts and offering potential for developing cost‐effective and efficient HER catalysts.

Amine-Functionalized Triazolate-Based Metal-Organic Frameworks for Enhanced Diluted CO2 Capture Performance.

Efficient CO2 capture at concentrations between 400-2000 ppm is essential for maintaining air quality in a habitable environment and advancing carbon capture technologies. This study introduces NICS-24 (National Institute of Chemistry Structures No. 24), a Zn-oxalate 3,5-diamino-1,2,4-triazolate framework with two distinct square-shaped channels, designed to enhance CO2 capture at indoor-relevant concentrations. NICS-24 exhibits a CO2 uptake of 0.7 mmol/g at 2 mbar and 25 °C, significantly outperforming the compositionally related Zn-oxalate 1,2,4-triazolate - CALF-20 (0.17 mmol/g). Improved performance is attributed to amino-functions that enhance CO2 binding and enable superior selectivity over N2 and O2, achieving 8-fold and 30-fold improvements, respectively, in simulated CO2/N2 and CO2/O2 atmospheric ratios. In humid environments, NICS-24 retained structural integrity but exhibited an 85 % reduction in CO2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO2 due to strong hydrogen-bonding interactions within the framework. Gained understanding of the interaction between CO2 and H2O within the MOF framework could guide the modification via rational design with improved performance under real-world conditions.

Ab Initio Predictions of Adsorption in Flexible Metal-Organic Frameworks for Water Harvesting Applications.

Metal-organic frameworks such as MOF-303 and MOF-LA2-1 have demonstrated exceptional performance for water harvesting applications. To enable a reticular design of such materials, an accurate prediction of the adsorption properties with chemical accuracy and fully accounting for the flexibility is crucial. The computational prediction of water adsorption properties in MOFs has become standard practice, but current methods lack the predictive power needed to design new materials. Limitations stem from the way the interatomic potential is described and the inadequate consideration of the framework flexibility. Herein, we showcase a methodology to obtain chemically accurate adsorption isotherms that fully account for framework flexibility. The method relies on very accurate and efficiently trained machine learning potentials and transition matrix Monte Carlo simulations to account for framework flexibility. For MOF-303, quantitatively accurate adsorption isotherms are obtained, provided an accurately benchmarked electronic structure method is used to train the machine learning potential, and local and global framework flexibility is accounted for. The broader applicability is shown through the study of MOF-333 and MOF-LA2-1. Analysis of the water density profiles in the MOFs gives insight into the factors governing the shape and origin of the isotherm. An optimal water harvester should have initial seeding sites with intermediate adsorption strength to prevent detrimental low-pressure water uptake. To increase the working capacity, linker extension strategies can be used while maintaining the initial seeding sites, as was done in MOF-LA2-1. The methodology can be applied to other guest molecules and MOFs, enabling the future design of MOFs with specific adsorption properties.