Search Results (404)

The nanoconfinement effect is crucial in unconventional oil and gas development, yet the regulatory mechanism of wettability on it remains unclear. In this study, three SBA type molecular sieves with different pore sizes were used as model materials. Isothermal adsorption experiments were conducted using a BET analyzer, and pore size distributions were determined using the BET method and the DFT method, to systematically investigate the influence of wettability on the nanoconfinement effect. The results show that SBA molecular sieves with different pore sizes exhibit significantly different propane adsorption behaviors. SBA-15-4.2 with smaller pore sizes undergo capillary condensation at lower pressures, while SBA-15 and SBA-15-18 with larger pore sizes require higher pressures. The pore size distribution of the mixed SBA molecular sieve system exhibits a weighted superposition characteristic of the individual material pore size distributions, with each material contributing differently in different pore size ranges. Wettability significantly affects gas adsorption, diffusion, and condensation processes: unmodified SBA molecular sieves are highly hydrophilic and unfavorable for propane adsorption; shale pore surfaces have complex wettability and exhibit unique adsorption preferences for propane. After hydrophobic modification, the isothermal adsorption curve of the oil-wet SBA composite system is closer to that of shale, and the shale isothermal adsorption curve can be well fitted by adjusting the proportion of SBA molecular sieves in the mixture. This study provides a theoretical basis and experimental means for understanding the production mechanisms of unconventional reservoirs and optimizing production technologies. Full article

Hydrogen is a promising clean-energy carrier, but its low ignition energy, high diffusivity, and wide flammability range demand reliable leak detection. Chemiresistive sensors based on n-type metal oxide semiconductors are attractive owing to their simple architecture, low cost, large resistance modulation, thermal robustness, and compatibility with miniaturized devices. This review focuses on n-type metal oxide semiconductor nanomaterials for hydrogen sensing, particularly ZnO, SnO₂, In₂O₃, WO₃, TiO₂, and related mixed oxides. The fundamental sensing mechanisms are examined, including oxygen chemisorption, electron-depletion-layer modulation, grain-boundary barrier control, catalytic hydrogen spillover, and hydrogen-induced surface reduction or metallization, together with the way these mechanisms compete and cooperate under different operating conditions. Recent performance-enhancement strategies are organized around morphology and porosity control, noble-metal sensitization, defect and dopant engineering, n–n heterojunctions, molecular sieving, and low-temperature activation. Density functional theory is discussed as a design tool for evaluating adsorption energetics, vacancy formation, work-function shifts, band alignment, and interfacial charge transfer, along with its current limitations for modeling humid surfaces. Finally, key challenges and future directions, including humidity tolerance, standardized reporting, device integration, and emerging materials, are summarized to guide the development of high-performance hydrogen sensors. Full article

To investigate the modulation effects of high temperature and molecular sieve acidity on olefin cracking pathways and product selectivity, the catalytic cracking performance of 1-pentene was systematically studied under catalytic cracking temperatures of 700, 750 and 800 °C over H-ZSM-5 molecular sieves with silica-alumina molar ratios (SAR) of 23, 42 and 95. The contributions of catalytic cracking and thermal cracking were quantified, and the synergistic effects of temperature and SAR on monomolecular cracking, bimolecular cracking, confined catalytic radical (CCR) reaction and side reactions were analyzed by composition of the cracking products. Results showed that catalytic cracking dominated the cracking of 1-pentene over H-ZSM-5 in 700–800 °C. Higher temperature promoted monomolecular cracking and CCR, thus significantly increasing ethylene selectivity. Lower SAR enhanced acidity and catalytic cracking activity but intensified aromatization and C₅₊ formation. HZ-95 with weak acidity favored bimolecular cracking and exhibited low ethylene selectivity. HZ-42 achieved the optimal performance at 800 °C, with 1-pentene conversion of 98.80% and ethylene molar selectivity of 82.41%; both hydrogen transfer reactions and methane formation were effectively suppressed. This work provides mechanistic insights and theoretical support for the targeted catalytic cracking to olefins (TCO) process. Full article

The presence of residual moisture in tetrahydrofuran (THF) greatly limits its suitability for moisture-sensitive processes, including polymerization, Grignard chemistry, and fine-chemical production, where the allowable water concentration is generally lower than 10 mg/kg. Here, a hierarchical microporous/mesoporous composite adsorbent was prepared via extrusion molding, combining an LTA-type zeolite microporous framework with an amorphous mesoporous matrix. Characterization by XRD, FTIR, SEM, and pore analysis confirmed that the LTA crystal structure was retained while mesopores provided channels for mass transport. Static dehydration tests showed that the composite reduced THF water content from 70 mg/kg to 8.3 mg/kg, compared to 23.4 mg/kg for commercial 3A molecular sieves. The enhanced performance arises from micropores supplying uniform adsorption sites for deep dehydration and mesopores accelerating diffusion. Water vapor adsorption, kinetic and isotherm analyzes, regeneration, and competitive adsorption experiments indicated improved water accessibility and high selectivity, with kinetics described by a double-exponential model. The adsorbent remained stable over six adsorption–regeneration cycles. These results demonstrate that hierarchical microporous/mesoporous structures effectively achieve deep THF dehydration. Full article

Resource recovery from excess sludge, specifically the extraction of extracellular polymeric substances (EPSs), has become a frontier issue; yet achieving high-value utilization of this recovered resource remains a key bottleneck. Two-dimensional MXene membranes show great potential for emerging contaminants (ECs) separation owing to their lamellar structure and tunable surface chemistry. In this study, biological macromolecule (BM)-intercalated MXene (BM-M) composite membranes were fabricated using practical EPSs and model EPSs such as sodium alginate (SA), bovine serum albumin (BSA), and silk fibroin (SF) as sustainable intercalators. The interlayer spacing, surface charge, hydrophilicity, mechanical strength, functional group of BM-M membranes and their EC removal behaviors were systematically investigated. The practical EPS performed better than the model EPS, highlighting the importance of molecular complexity in interlayer design. The practical EPS-intercalated MXene (EPS-M) membrane achieved the removal efficiencies of 64.0%, 90.2% and 67.5% for diethyl phthalate (DEP), erythromycin (ERY) and sulfamethoxazole (SMX), respectively. The separation mechanism of ECs mainly included electrostatic, sieving, hydrophobic, and hydrogen bonding. This work highlights the effectiveness of EPS intercalation in tailoring MXene membrane structure for the removal of diverse ECs. Full article

Radium and barium are hazardous contaminants that frequently occur in wastewater, posing significant risks to human health and the environment. This study provides a comparative evaluation of five synthetic zeolites—3A, 4A, 5A, 13X (commercial), and NaP1 (synthesized from fly ash)—representing three distinct framework types (LTA, FAU, and GIS) for the removal of radium from real saline mine water (Upper Silesia Coal Basin, Poland) and barium from synthetic water. The zeolites were characterized by XRD, SEM-EDS, and N₂ adsorption, and tested in both granular and fine-powder forms using sequential batch adsorption experiments. For radium removal from mine water, zeolite NaP1 demonstrated superior performance, maintaining low ²²⁶Ra effluent activity (<1 Bq/L), even after treating ~50 L of water. Zeolites 3A, 4A, 5A, and 13X exhibited significantly lower performance than NaP1, showing poor selectivity for radium. In the barium batch tests, all tested zeolites achieved removal efficiencies exceeding 95% at low initial concentrations (100 mg/L). At higher concentrations (2000 mg/L), zeolites 3A, 4A, and 13X exhibited the highest adsorption capacities, with zeolite 4A achieving the maximum value of approximately 239.9 mg/g. The experiments demonstrated that idealized laboratory conditions can substantially overestimate sorbent performance relative to real water systems. Full article

Rational design of smart nanogels for drug delivery requires molecular-level understanding of how structural evolution and drug–carrier interactions couple under multiple stimuli. Here, pH/temperature dual-responsive P(NIPAM-co-AAc) nanogels containing 0–20 mol% AAc were investigated by combining all-atom molecular dynamics simulations with in vitro ibuprofen (IBU) release experiments under acidic (pH 2.75) and weakly basic (pH 7.4) conditions at 298 and 310 K. The simulations identified CA-5-L-298 as the most retained system, with the lowest IBU diffusion coefficient (0.92 × 10⁻⁷ cm² s⁻¹) and no dissociated molecules under the adopted criterion, whereas CA-15-H-310 showed the highest diffusivity (8.61 × 10⁻⁷ cm² s⁻¹) and dissociated fraction (22%). Consistently, in the urea-free release experiments, CA-15-H-310 exhibited the highest 24 h cumulative release (69.4%), while CA-5-L-298 remained among the low-release systems (35.9%). Pore analysis, hydrogen-bond statistics, MM/PBSA calculations, and urea-competition experiments together support the view that IBU release is influenced by both mesh steric sieving and polymer–drug affinity switching, and correlation analysis provides quantitative support for linking the MD descriptors with the experimental release behavior. Overall, the simulations reproduce the qualitative trends in the experiments and provide a molecular-level framework for rationalizing the observed release behavior in dual-responsive nanogels. Full article

In this study, a polyethylene glycol (PEG)-based solid electrolyte composite (PEG)₁₀LiClO₄/NaAlOSiO suitable for anodic bonding packaging was successfully fabricated via a combined ball milling and hot pressing process. The micromorphology, ion transport characteristics, and mechanical packaging properties of the composite were systematically investigated using characterization techniques including electrochemical impedance spectroscopy, X-ray diffraction, scanning electron microscopy, and anodic bonding performance tests. The results demonstrate that doping with NaAlOSiO molecular sieve can effectively reduce the crystallinity of the polymer matrix, construct more efficient carrier transport pathways, and simultaneously enhance the ionic conductivity and mechanical properties of the material. When the mass fraction of NaAlOSiO doping is 8 wt.%, the composite exhibits a room temperature ionic conductivity of up to 1.31 × 10⁻⁵ S·cm⁻¹. Under room temperature and a bonding voltage of 800 V, the sample with this doping ratio achieves the optimal anodic bonding with metallic Al, and the tensile strength of the bonding interface reaches 5.93 MPa, showing excellent application prospects in micro–nano-packaging. Full article

Developing an ultrasensitive electrochemiluminescence (ECL) detection platform remains challenging due to the limited enrichment efficiency of ECL emitters and co-reactants at the electrode interface, as well as the insufficient catalytic enhancement of co-reactant conversion. Moreover, simultaneous in situ analyte enrichment and efficient anti-interference capability are often difficult to achieve in a single sensing interface. Herein, a new ECL platform was developed based on nanocatalyst-supported nanochannel-confined surfactant micelle (SM) system, which integrates an enhanced luminol-dissolved oxygen (DO) ECL response for the ultrasensitive detection of antibiotic rifampicin (RIF). A nanocomposite comprising nitrogen-doped graphene quantum dots and a molybdenum disulfide nanosheet (NGQDs@MoS₂) was modified on an indium tin oxide (ITO) electrode. This nanocomposite layer catalyzed the oxygen reduction reaction (ORR), boosting the co-reactant efficiency of DO. Vertically ordered mesoporous silica film filled with surfactant micelles (SM@VMSF) was subsequently grown in situ on the NGQDs@MoS₂ surface. The hydrophobic micelles enable the simultaneous enrichment of luminol, DO, and RIF. Integrating the triple-enrichment effect of surfactant micelles with the high electrocatalytic effect of NGQDs@MoS₂ nanocomposite results in significant ECL enhancement of the luminol–DO. SM@VMSF also provides an excellent molecular sieving effect, endowing the sensor with high anti-interference capability and stability. RIF quenches the ECL signal by consuming superoxide anion radicals, enabling sensitive detection. Detection of RIF was established with a high sensitivity (2927 a.u. per nM) wide linear range (10 pM to 10 μM) and a low limit of detection (LOD, 2.5 pM). The fabricated sensor exhibits good selectivity and high fabrication reproducibility (relative standard deviation, RSD, of 1.9%). Additionally, the determination of RIF in eye drops and seawater samples was realized. This work offers new insights for the design of high-performance ECL sensing interfaces and sensitive detection of RIF. Full article

The global energy transition and the implementation of carbon capture, utilization, and storage (CCUS) strategies require energy-efficient and scalable CO₂ separation technologies. Mixed-matrix membranes (MMMs), combining polymer matrices with functional inorganic or hybrid nanofillers, have emerged as advanced separation platforms capable of surpassing the conventional permeability–selectivity trade-off observed in neat polymer membranes. This review critically evaluates recent developments in modern hybrid membranes for CO₂ separation from synthetic and industrial gas mixtures, including CO₂/N₂ (flue gas), CO₂/CH₄ (natural gas and biogas upgrading), and syngas systems. Particular emphasis is placed on MMMs incorporating covalent organic frameworks (COFs), metal–organic frameworks (MOFs), graphene oxide (GO), MXenes, transition metal dichalcogenides (TMDs), carbon nanotubes (CNTs), g-C₃N₄, layered double hydroxides (LDH), zeolites, metal oxides, and magnetic nanoparticles. Reported performance ranges include CO₂ permeability (P_CO2) typically between 100 and 800 Barrer, CO₂/N₂ selectivity up to 319, and CO₂/CH₄ selectivity up to 249, depending on filler chemistry, loading, and interfacial compatibility. The mechanisms governing gas transport—molecular sieving, selective adsorption, facilitated transport, and diffusion-pathway engineering—are systematically discussed. Key challenges addressed include filler dispersion, polymer–filler interfacial defects, physical aging, moisture sensitivity, oxidation (particularly in MXenes), and scalability toward industrial membrane modules. Future perspectives focus on sub-nanometer pore engineering, surface functionalization to enhance CO₂ affinity, controlled alignment of 2D nanosheets to promote directional transport, multifunctional core–shell and hollow structures, and the integration of computational modeling and machine learning for accelerated material design. Modern hybrid MMMs are identified as strategically important materials enabling high-efficiency CO₂ separation processes aligned with decarbonization and energy transition objectives. Full article

As an efficient dry separation technology, electrostatic separation exhibits significant potential for application in the sorting and recovery of carbon-rich resources from coal gasification fine slag (CGFS). The small particle size and high moisture content of CGFS particles are the main factors affecting the efficiency of separation. This study proposes a method integrating particle moisture reduction and charging promotion based on molecular sieves, with the aim of investigating its feasibility in improving the electrostatic separation efficiency of CGFS particles. The results indicate that molecular sieves can effectively adsorb moisture from the ambient humid air and the surface of particles, allowing for rapid drying of wet particles. The reduction in moisture content on the particle surfaces significantly promotes their charging capability, creating favorable conditions for electrostatic separation. After molecular-sieve-assisted charging enhancement, the carbon content in the ash-enriched positive plate product decreased by 4.96%, while the carbon content in the carbon-enriched negative plate product increased by 12.15%, indicating a significant improvement in carbon–ash separation efficiency. Correspondingly, the decarbonization efficiency of the positive plate and carbon recovery efficiency of the negative plate were increased by 21.30% and 52.17%, respectively. Furthermore, when the moisture content exceeds 10%, the phenomenon of inter-particle agglomeration can adversely affect the separation of carbon and ash particles. The most suitable operating conditions are a moisture content no higher than 10%, an electric field density of 30 kV/m, a filling molecular sieve of 400 g, and a gas velocity of 12 m/s (volumetric flow rate 84.78 m³/h). In practical industrial applications, it is advisable to consider pre-treating the particles for drying or employing secondary separation to enhance sorting accuracy. Full article

Direct air capture (DAC) of CO₂ via temperature-swing adsorption (TSA) can support sustainable carbon dioxide removal, but only if sorbents regenerate with low energy demand and maintain performance under humid ambient air. In this paper, we evaluate three commercial molecular sieves (JLPM3, 13X, and 4A) in packed-bed tests using humid ambient air. We compared 40 g samples as received with 200 g samples conditioned for 12 days at 100 °C to emulate prolonged exposure to regeneration temperature (the cumulative effect of many heating/desorption cycles); all cycle-stabilized uptake values are reported from the conditioned materials. JLPM3 delivered the highest stabilized CO₂ uptake (0.24 ± 0.01 mmol·g⁻¹), consistent with a combined physisorption/chemisorption mechanism. Its higher total porosity (26.190%) and smaller mesopores (7.569 nm width) promoted rapid mass transfer and site accessibility, while slightly greater micropore area (710.285 m²·g⁻¹) and volume (0.267 cm³·g⁻¹) than 13X supported its marginally higher capacity. Evidence of partial structural degradation under mechanical and thermal stress indicates that minimizing strain during cycling will be important for scale-up and for reducing sorbent replacement. Conditioning at 100 °C activated additional chemisorption sites across all sieves but reduced physisorption capacity. Importantly, a ~100 °C desorption step fully regenerated physisorbed CO₂ while purging moisture from zeolite pores, indicating that low-temperature TSA (compatible with low-grade or waste heat) can replace harsher 300 °C regeneration and lower energy demand. CO₂–H₂O competition experiments confirmed substantial site occupancy by water vapor, which limits capture under humid conditions and motivates water management strategies. Overall, maximizing DAC performance requires tailoring pore structure and operating conditions while preserving sorbent integrity; JLPM3 emerges as a promising candidate for more energy- and resource-efficient DAC. Full article

Craniosynostosis is the premature fusion of skull bones due to loss of stem/progenitor cells located in non-mineralized tissue between growing cranial bones of infants. We generated scaffolds from a biodegradable biomaterial with small interconnected pores (125–250 μm diameter), previously shown to maintain stemness of a mesenchymal cell population, to further develop a method for the creation of an artificial cranial bone stem cell niche. Polymer scaffolds of consistent pore size were fabricated using a molecular-sieved sugar sphere casting technique with poly-l-lactic acid. A rectangular surgical defect within the parietal bone of juvenile mice was created. The three groups included sham animals with surgery but no scaffold, experimental animals with surgery plus an implanted cell-free scaffold, and experimental animals with surgery plus an implanted bone mesenchymal cell-seeded scaffold. Healing at the surgical site was evaluated at 4 and 12 weeks after surgery by micro-CT and histology. Surgical site bone volume fraction and bone mineral density were significantly greater at twelve than four weeks in the sham group but not in either of the scaffold groups. At twelve weeks, the surgical site bone volume fraction and bone mineral density were significantly lower in the cell-seeded scaffold as compared to the sham animal group. At twelve weeks, the anterior and middle cranial vault widths were significantly greater in the cell-seeded scaffold as compared to the sham animal group on the surgery side of the skulls. Less mineralization was evident within the cell-seeded than the cell-free scaffolds by histology. Based on these findings, scaffolds of sufficiently small pore size seeded with autologous bone mesenchymal stem cells could function as an artificial cranial stem cell niche to inhibit surgical-site mineralization and promote cranial growth. Full article

Carbon molecular sieve membranes (CMSMs) provide a means to greatly improve gas separations. CMSMs have a pore size distribution comprising micropores and ultramicropores which provide high flux and high selectivity, enabling them to outperform polymeric membranes. CMSMs, however, suffer from physical aging that results from the collapse of the pores that severely reduces their gas permeability. Therefore, reducing physical aging of CMSMs is an important step in the development of these types of materials. In this work, a method for reducing physical aging through the incorporation of metal nanoparticles that serve as a structural scaffold for the membrane pore structure is presented. The pore structure in CMSMs is dependent upon the polymeric precursor, and thus the support system incorporated must be tailored. The copper nanoparticles were formed in situ from soluble, copper-based metal–organic polyhedra 18 (MOP-18) dispersed into Matrimid^® 5218, a low free volume polymer. The size (2 to 20 nm) and shape (sphere, rods) of the copper particles were refined by adjusting MOP-18 loading, pyrolysis temperature, and soaking time. The Cu-pillared Matrimid^® 5218 CMSMs from this work showed no decline in permeability or selectivity for methane (107 Barrer) and carbon dioxide (1785 Barrer) over a period of 21 d. The results suggest that tailored metal pillars can suppress physical aging in CMSMs, thereby enhancing their long-term stability and applicability in gas separations. Full article

Conventional high-temperature calcination for activating MFI zeolite membranes is energy-intensive and prone to inducing defects. Here, we demonstrate that a rapid ozonation treatment at 200 °C for only 1 h effectively decomposes organic templates while preserving membrane integrity. The resulting membrane exhibits H₂/CH₄ and H₂/N₂ ideal selectivities of 10.3 and 6.5, respectively, at room temperature, with C₃H₈ and SF₆ permeances below the detection limit. These results confirm a dense, defect-minimized architecture and good molecular sieving performance of the zeolite membrane. In contrast, extending ozonation to 48 h leads to defect formation and a marked reduction in selectivity. For H₂/CH₄ mixture separation, the membrane achieves a selectivity of 23.8 at 100 °C, which is highly competitive among reported MFI membranes. In isopropanol dehydration, it achieves a water flux of 2.3 kg·m⁻²·h⁻¹ and a separation factor of 3278 at 70 °C with a 10 wt% water feed, while maintaining >99.5 wt% water content in the permeate over a broad operating temperature range (30–70 °C). This work establishes rapid ozonation as a scalable, energy-efficient activation method for high-performance MFI zeolite membranes in both gas and liquid separations. Full article