Increase In Pore Size Research Articles

Tailoring pore size of mesoporous silica and organosilica using biodegradable pentablock copolymer templates via EISA process

In this work, we have designed unique poly(lactic acid-co-glycolic acid)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(lactic acid-co-glycolic acid) pentablock copolymers using Pluronic F68 and F108 triblock copolymers as macroinitiators. The poly(lactic acid-co-glycolic acid) (PLGA) blocks were attached as glycolide and lactide monomers at the both ends of each F68 and F108 triblock copolymer. The molecular weights and the block fractions were confirmed by gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) for the four kinds of pentablock copolymers. Using these pentablock copolymers as templates, we synthesized mesoporous ethane-silicas as well as silicas by the evaporation-induced self-assembly (EISA) method. 1,2-bis(triethoxysily)ethane (BTEE) were used as an organosilica precursor. The mesoporous ethane-silica samples were characterized using synchrotron small angle X-ray scattering (SAXS), nitrogen sorption experiments, transmission electron microscopy (TEM), and solid-state 29Si CP-MAS NMR. Based on the experimental results, it was confirmed that the porosity and pore diameter can be varied with the PLGA weight fraction of the pentablock copolymer. It is due to the PLGA block in polymer forming the hydrophobic domain in micelles, which leads to the formation of increased pore size over 20 nm without any additive pore expander. In addition, it seems that as the organosilica precursor increases, the association number of block copolymers forming one micelle decreases, resulting in a decrease in pore size. In summary, the polymer template plays a vital part in tuning the structure of the mesoporous ethane-silica samples. Thus, the development of synthetic method of mesoporous organosilica materials using polymer templates with different topology is still challenging and can endow the unique structure and property for mesoporous organosilica for future applications.

Boosting Bulk Oxygen Transport with Accessible Electrode Nanostructure in Low Pt Loading PEMFCs.

Despite the high potential for reducing carbon emissions and contributing to the future of energy utilization, polymer electrolyte membrane fuel cells (PEMFCs) face challenges such as high costs and sluggish oxygen transport in cathode catalyst layers (CCLs). In this study, the impact of pore size distribution on bulk oxygen transport behavior is exploredby introducing nano calcium carbonate of varying particle sizes for pore-forming. Physicochemical characterizationsfor are employed to examine the electrode structure, while in situ electrochemical measurements are used to scrutinize bulk oxygen transport resistance, effective oxygen diffusivity ( ) and fuel cell performance. Additionally, the CCLs are constructed with aid of Lattice Boltzmann method (LBM) simulations and for CCLs with different pore size distribution are calculated. The findings reveal that initially increases and then decreases as the most probable pore size increases. A "sphere-pipe" model is proposed to describe practical bulk oxygen transport in CCLs, highlighting the significant role of not only the pore size of secondary pores but also the number of primary pores in bulk oxygen transport.

Fabrication of a novel porous nanostructure based on NiCuFe2O4@MCM-48, embedded with graphene oxide/poly (p-phenylenediamine) to construct an efficient supercapacitor

In this study, a new nanocomposite was created by combining copper-doped nickel ferrite (NiCuFe2O4) nanoparticles with MCM-48 (Mobil Composition of Matter No. 48) on a graphene oxide (GO) substrate functionalized with poly(ρ-phenylenediamine) abbreviated as (PρPD). This nanocomposite was developed to investigate its potential for enhancing the function of a supercapacitor in energy storage. Following NiCuFe2O4@MCM-48 preparation, Hummer’s technique GO was applied. In-situ polymerization of NiCuFe2O4@MCM-48/GO nanoparticles with ρ-phenylenediamine (ρPD) in the presence of ammonium persulfate (APS) produced PρPD, a conductive polymer. Structural characterization of the nanocomposite includes FTIR, XRD, VSM, TGA-DTG, EDX, and FE-SEM. Results from BET indicate a pore size increase of up to 5 nm. Fast ion penetration and higher storage in capacitor material are explained by this. Additionally, the nanocomposite’s electrochemical performance was evaluated using GCD and CV tests. The NiCuFe2O4@MCM-48/GO/PρPD nanocomposite has a specific capacitance of 203.57 F g−1 (1 A g−1). Furthermore, cyclical stability is essential for energy storage applications. The nanocomposite retains 92.5% of its original capacitance after 3000 cycles, indicating outstanding electrochemical stability.

Effects of porous substrates on the structure of turbulent boundary layers

Three different porous substrates (with different pore sizes, $s$ , and permeabilities, $K$ ) are used to examine their effect on the structure of boundary layer flow over them. The flow is characterised with single-point hot-wire measurements as well as planar particle image velocimetry. In order to elucidate differences in shallow and deep flows past porous substrates, foams with two different thicknesses ( $h$ ) are used (for all three substrates). A wide range of friction Reynolds numbers ( $2000< Re_\tau <13\,500$ ) and permeability-based Reynolds numbers ( $1< Re_K< 50$ ) are attained. For substrates with $Re_K \sim 1$ , the flow behaviour remains similar to flow over impermeable smooth walls and as such Townsend's hypothesis remains valid. Very large-scale motions are observed over permeable foams even when the $Re_K > 1$ . In contrast, a substantial reduction in velocity disturbances and associated length scales is achieved for permeable foams with intermediate values of pore density and relative foam thickness ( $h/s$ ), which affects outer-layer similarity. As permeability is increased by increasing pore size, the foam becomes sparse relative to viscous scales at high Reynolds numbers. For such foams, the flow conforms to outer-layer similarity and is more akin to flow over rough surfaces. Permeability attenuates the wavelengths associated with the outer-layer peak.

A novel approach to tailoring the microstructure and electrophysical properties of Ni/GDC-based anodes by combining 3D-inkjet printing and layer-by-layer laser treatment

This work proposes an original method for tailoring the microstructure and electrical properties of Ni/GDC anodes by using 3D inkjet printing of high-viscosity functional compositions with intermediate laser treatment of each layer after each printing pass. Based on a mixture of highly dispersed oxides NiO and CeO2 doped with gadolinium (GDC), paste formulations for 3D inkjet printing have been developed. The effects of 3D printing and laser treatment conditions on the porosity and shrinkage ratio of the NiO/GDC anodes during sintering were investigated. The reduction of the anode support workpieces to produce Ni/GDC cermet was carried out and the effect of laser exposure on the morphology and electrical characteristics of the resulting samples was studied. It was found that an increase in the laser exposure values during layer-by-layer laser treatment of printing compositions leads to a two-fold increase in the porosity of the solid oxide fuel cell components, an increase in the average pore size from 0.2 to 0.3 to 2–5 μm, and to a five-fold decrease in the sintering shrinkage ratio. It was also found that the electrical conductivity of the Ni/GDC cermet, produced by the reduction of the laser treated NiO/GDC, increased by 5–10 times as the laser exposure values increased. The influence mechanism of the layer-by-layer laser treatment of the original NiO/GDC samples on the electrical conductivity of their reduced counterparts, Ni/GDC cermet anodes, has been proposed. An increase in the electrical conductivity was shown to be due to in situ reduction of NiO, partial sintering of Ni nanoparticles and the formation of a percolation network. This new method of hybrid 3D printing opens up great prospects for tailoring the morphological and electrical characteristics of SOFC anode supports.

Optimizing design of catalyst layer structure with carbon-supported platinum weight ratio mixing method for proton exchange membrane fuel cells

The design of catalyst structure of proton exchange membrane fuel cells (PEMFCs) functions a crucial role in water and reactants transport. In this work, catalyst layer is designed to mixing strategy of commercial Pt/C catalysts with various weight ratios (20 wt%, 40 wt%, and 20 + 40 wt%). Our mixing strategy demonstrates beneficial effects for optimized catalyst structure, leading to improved electrochemical performance and durability. Mix weight ratio Pt/C (as we abbreviated 20 + 40 wt% to Mix wt%) confirmed the optimized morphology through physical characterization and verified through electrochemical characterization under varying relative humidity (RH) conditions. Remarkably, Mix wt% Pt/C showed the highest electrochemical performance at 40–120 % RH, with a maximum power density elevation of ∼42 % and charge transfer resistance improvement of ∼40 % under low humidity conditions. This enhancement can be attributed to the improved mass transport resulting from increased pore size and reduced distortion in transport pathways. Additionally, we performed a 5,000 cycle accelerated stress test (AST), demonstrating enhanced durability in Mix wt% Pt/C. Our strategy provides a reproducible and simplified process to achieve higher fuel efficiency. Moreover, we anticipate that this offers the potential to enhance both performance and durability in commercial PEMFC applications.

The bitumen development effect on the pore structure and electrical resistivity of carbonate reservoirs in the Sinian Dengying Formation

Abstract In the Sichuan Basin, bitumen widely distributes in the carbonate reservoir, and the bitumen occurrence morphology affects the pore structure and petrophysics. Two types of bitumen, boundary-filled and centre-filled, were reconstructed using a pore morphology-based method based on dolomite carbonate digital cores from X-ray computerized tomography. The pore structures of the reconstructed bitumen-filled digital core models were determined using an extracted pore network model. The finite element method simulated the electrical resistivity of the digital core model. The investigation showed that (i) boundary-developed bitumen increases the pore size whereas centre-developed bitumen decreases the pore size, and bitumen development increases the shape factor while reducing the coordination number; (ii) for electrical resistivity, boundary-filled bitumen increases the porosity exponent with increasing pore size, whereas centre-filled bitumen decreases the porosity exponent. Bitumen development caused a negative correlation between the porosity exponent and pore shape factor, a logarithmic increase between the porosity exponent and coordination number, and a power increase between the porosity exponent and porosity. Subsequently, a new porosity exponent model related to porosity was proposed based on the curve-fitting method. This new porosity exponent combines the Archie equations to calculate the saturation of the carbonate reservoir in the Sinian Dengying Formation in the Penglai gas area on the northern slope of the central Sichuan paleo-uplift, which fits the sealed core plug saturation well and provides the basis for further reservoir evaluation and fluid identification in the Penglai gas area.

Characteristics of Electrical Resistance Alteration during In Situ Leaching of Ion-Adsorption-Type Rare Earth Ore

The chemical reaction of ion-adsorption-type rare earth ore during the in situ leaching process is accompanied by ion migration and charge movement, making the leaching process electrochemical in nature. The chemical reaction rate plays an important role in the leaching rate of rare earth elements. In this work, electrochemical impedance spectroscopy (EIS) was used to reveal the characteristics of electrical resistance alterations and leaching rate of rare earth elements during in situ leaching. The equivalent circuit model of the leaching process was established, and two critical parameters of solution resistance Rs and charge transfer resistance Rt were analyzed to reflect the electrochemical characteristics. According to the characteristics of electrical resistance alteration, the leaching process was divided into four stages: wetting, reaction, equilibrium, and top water stage. The resistance parameters Rs and Rt decreased first and then increased during the leaching process. The maximum value of Rs was 1330 Ω∙cm2 at the end of the top water stage, and the minimum value was 125 Ω∙cm2 at the beginning of the equilibrium stage. The maximum value of Rt was 8310 Ω∙cm2 at the beginning of the leaching stage, and the minimum value was 21 Ω∙cm2 at the end of the reaction stage. Rs and Rt were negatively correlated with the pore size and chemical reaction rate during leaching. With an increasing pore size and reaction rate, the resistance parameters decrease. This study provides a new idea for the intelligent monitoring of rare earth ore.

Full-Scale Pore Structure Characterization and Its Impact on Methane Adsorption Capacity and Seepage Capability: Differences between Shallow and Deep Coal from the Tiefa Basin in Northeastern China

Deep low-rank coalbed methane (CBM) resources are numerous and widely distributed in China, although their exploration remains in its infancy. In this work, gas adsorption (N2/CO2), mercury intrusion porosimetry, and 3D CT reconstruction were performed on five coal samples of deep and shallow low-rank coal from northeast China to analyze their pore structure. The impact of the features in the pore structure at full scale on the capacity for methane adsorption and seepage is discussed. The results indicate that there are significant differences between deep low-rank coal and shallow low-rank coal in terms of porosity, permeability, composition, and adsorption capacity. The full-scale pore distribution was dispersed over a broad range and exhibited a multi-peak distribution, with the majority of the peak concentrations occurring between 0.45–0.7 nm and 3–4 nm. Mesopores are prevalent in shallow coal rock, whereas micropores are the most numerous in deep coal rock. The primary contributors to the specific surface area of both deep and superficial coal rock are micropores. Three-dimensional CT reconstruction can characterize pores with pore size greater than 1 μm, while the dominating equivalent pore diameters (Deq) range from 1 to 10 μm. More mini-scale pores and fissures are observed in deep coal rock, while shallow coal rock processes greater total and connection porosity. Multifractal features are prevalent in the fractal qualities of all the numbered samples. An enhancement in pore structure heterogeneity occurs with increasing pore size. The pore structure of deep coal rock is more heterogeneous. Furthermore, methane adsorption capacity is favorably connected with D1 (0.4 nm < pore diameter ≤ 2 nm), D2 (2 nm < pore diameter ≤ 5 nm), micropore volume, and specific surface area and negatively correlated with D3 (5 nm < pore diameter ≤ 50 nm), showing that methane adsorption capability is primarily controlled by micropores and mesopores. Methane seepage capacity is favorably connected with the pore volume and connected porosity of macropores and negatively correlated with D4 (pore diameter > 50 nm), indicating that the macropores are the primary factor influencing methane seepage capacity.

ФРАКТАЛЬНАЯ РАЗМЕРНОСТЬ ПОРИСТОЙ СТРУКТУРЫ ЯЧЕИСТОГО БЕТОНА

The study of the fractal dimension of pores in cellular concrete and aerated concrete blocks significantly influences the understanding of the porous structure of materials. One of the key methods for estimating this dimension is cell counting. The fractal dimension of pores indicates the degree of their dense distribution and is closely related to the physical properties of the material, such as heat and sound insulation. The results of the study showed that an increase in the fractal dimension of pores is associated with an increase in the number of smallest pores and the complication of their spatial arrangement. At the same time, the use of the cell counting method allows to estimate accurately this fractal dimension, based on the number of cells containing pores at different scales. One of the significant aspects is the correlation of the fractal dimension of pores with their area and size. This makes it possible to evaluate the roughness of pores and their distribution in the material, as well as to understand how an increase in pore size leads to a decrease in their number and thickening of the walls between them. The fractal dimension of pores makes it possible to characterize the structure of the pore space, which is important for understanding the microstructure of the material. Manipulating the microstructure of cellular concrete using fractal dimension analysis can improve its thermal insulation, strength and sound insulation, opening new possibilities for creating more efficient building materials

Molecular Dynamics Simulation Study on the Occurrence of Shale Oil in Hybrid Nanopores.

The molecular dynamics simulation was used to simulate the influence of the composite wall stacking effect on shale oil occurrence. The kerogen-illite heterogeneous wall pore model was established to study the effects of temperature, pore size, and wall component ratio on the adsorption ratio and diffusion capacity of shale oil. The calculation results show that the fluid density distribution in the hybrid nanopore is not uniform. When the pore size increases, the proportion of the first adsorption layer to the total adsorption amount decreases rapidly, and the phenomenon of the "solid-like layer" of shale oil in small pores is more obvious. In addition, increases in temperature have little effect on the density peak of the first adsorption layer. With increases in organic matter content in the shale pore model, the diffusion coefficient of fluid decreases gradually, along with adsorption capacity. The influence of the irregular arrangement of kerogen molecules on the adsorption of shale oil is greater than the influence of surface roughness caused by illite on the adsorption.

Effects of void defects on the mechanical properties of biphasic calcium phosphate nanoparticles: A molecular dynamics investigation

Porous biphasic calcium phosphate (BCP) ceramics are widely used in bone tissue engineering, and the mechanical properties of BCP implants must be reliable. However, the effects of pore structure (e.g., shape and size) on the mechanical properties are not well understood. In this study, we used molecular dynamics simulations to investigate the influence of pore shape and size on the mechanical behavior of BCP nanoparticles. BCP void models with cylindrical and cuboid pores ranging from 2 to 16 nm in diameter were constructed, and the elastic moduli were calculated. In addition, uniaxial tensile and compressive tests were performed on the models. We found that the pore size had a more significant impact on the mechanical properties of BCP than pore shape. Further, the elastic moduli decreased nonlinearly with increasing pore size. In addition, the tensile and compressive strength also decreased with the increase in pore size, but the ductility improved. Furthermore, deformation and fracture were more likely to occur near the pores and at the phase interfaces as a result of high atomic local strain in the calcium-deficient hydroxyapatite area. The results of this work reveal the effects of pore parameters on the mechanical properties of porous BCP at the nanometer level, which may aid the design of improved porous and multiphase CaP-based biomaterials for bone regeneration.

The effect of 3D-printed bone tissue scaffolds geometrical designs on bacterial biofilm formation

Bone fractures are recognized as a global health problem. A common strategy to tackle this issue is to employ a tissue engineering scaffold to accelerate tissue healing. However, one of the main challenges that can result in delaying the recovery is the risk of bacterial infections. This study aims to assess the impact of the geometry and the porosity of tissue scaffolds on the Staphylococcus aureus biofilm formation. Three triply periodic minimal surface designs of Schwarz primitive (SP), gyroid (GY), and Schwarz diamond (SD) and re-entrant auxetic (RE) design were examined and compared to a reference design (RD) considering two different porosity levels of 75% and 45%. The amount of biofilm was quantified using crystal violet assay and was visualized using scanning electron microscopy. The SP scaffold, with low porosity, exhibited a significantly less amount of bacterial biofilm formation and was regarded as having the best design among the others, while the SD with low porosity showed the greatest amount of biofilm. The morphological analysis was also in line with the crystal violet assay results. On the other hand, the surface roughness was affected by the complexity, geometrical variations, and limitations of fused filament fabrication three-dimensional printing. For the RD, SP, GY, and SD designs, an increase in surface roughness was demonstrated to increase the production of bacterial biofilms. Without statistical significance, the RE design showed the opposite trend. Contrary to other designs, the increase in pore size of the SP and GY designs was associated with the development of bacterial biofilms. This study suggests that it is possible to minimize the likelihood of bacterial biofilm formation by optimizing the scaffold geometry and its manufacturing.

Enhanced adsorption performance of varying-length mRNA on Oligo dT affinity resins through optimal pore size and grafting

The enormous potential of mRNA-based therapeutics in vaccines and medicine has led to the consideration of various mRNA sizes, ranging from ∼1000 to 10,000 nucleotides (nt). However, the commonly used Oligo-deoxythymidine (Oligo dT) affinity resins are not initially designed for such a wide range of sizes, and present challenges in achieving optimal performance for the separation of a given mRNA. In this paper, two factors of the resin beads, pore size and grafting were focused. The effects of varying pore sizes, ranging from 150 to 850 nm, on both static and dynamic adsorption for varying-length mRNA (1000–8500 nt) were investigated. It was found that static adsorption capacity and uptake kinetics were correlated with the mRNA length. Interestingly, dynamic binding capacities (DBCs) showed an increase-then-decrease trend with increasing pore size. An optimal pore size of about 350 nm could lead to the highest DBCs for all tested mRNA. Additionally, the effects of polymer grafting on the adsorption performance were studied. The results revealed that polymer-grafted resin exhibited 24–55% higher DBCs than non-grafted resin. The enhanced DBCs could be attributed to the improved uptake rate facilitated by the polymer grafted. These investigations emphasize the importance of optimizing pore size and grafting for Oligo dT affinity resins, providing valuable guidance for selecting and designing new resins for different mRNA products.

Surface-modified deproteinized human demineralized tooth matrix for bone regeneration: physicochemical characterization and osteoblast cell biocompatibility.

Tooth presents an intriguing option as a bone graft due to its compositional similarity to bone. However, the deproteinized human demineralized tooth matrix (dpDTM), developed to overcome the limited availability of autologous tooth grafts, has suboptimal pore size and surface roughness. This study aimed to fabricate a surface-modified dpDTM using acid etching and collagen coating, followed by in vitro evaluation of physicochemical and biological properties. The dpDTM was modified into two protocols: Acid-modified dpDTM (A-dpDTM) and collagen-modified dpDTM (C-dpDTM). Results demonstrated that A-dpDTM and C-dpDTM had increased pore sizes and rougher surfaces compared to dpDTM. Collagen immobilization was evidenced by nitrogen presence exclusively in C-dpDTM. All groups had a Ca/P molar ratio of 1.67 and hydroxyapatite as the sole constituent, with 65-67% crystallinity. Degradation rates significantly increased to 30% and 20% for C-dpDTM and A-dpDTM, respectively, compared to 10% for dpDTM after 120 days. Cumulative collagen release of C-dpDTM on Day 30 was 45.16 µg/ml. Osteoblasts attachment and proliferation were enhanced on all scaffolds, especially C-dpDTM, which displayed the highest proliferation and differentiation rates. In conclusion, surface modified of dpDTM, including A-dpDTM and C-dpDTM, significantly enhances bioactivity by altering surface properties and promoting osteoblast activity, thereby demonstrating promise for bone regeneration applications.

Adsorption of aqueous Cr (VI) onto UiO66NH2 MOF: Isotherm, thermodynamics and mechanism studies

As a member of the UiO-66 family, UiO66NH2 MOF (UNH) possessed enhanced stability, high surface area, increased pore size, and pore volume. Additionally, its amino groups offer spectacular affinity to capture Cr (VI). With these propitious features, UNH was fabricated by a facile solvothermal route in this study. It was then characterized by XRD and FTIR to confirm its successful formation. Its affinity towards efficacious capture of aqueous Cr (VI) was explored with the help of isotherm models and thermodynamic parameters. The Langmuir isotherm model fits best the experimental data, demonstrating monolayer Cr (VI) sorption on a homogenous UNH surface. The maximum adsorption capacity was determined as 51 mg/g. Negative ΔG° values suggested that the Cr (VI) uptake process is spontaneous and favorable, while the endothermic nature of the sorption was evident from positive values ΔH°. Thermodynamic parameters such as standard enthalpy change (ΔH°), standard entropy change (ΔS°), and standard Gibbs free energy change (ΔG°) were determined as 6.651 kJ mol−1, –3.216 kJ mol−1, and 33.76 KJ K−1.mol−1 respectively. FTIR and pH studies evidenced that the sequestration of Cr (VI) onto UNH proceeds through the electrostatic attraction mechanism, supported by the fitted isotherm model and thermodynamic parameters’ results.

Porosity and hardness of corn extrudates using dry tomato pomace

The incorporation of fiber-rich non-starchy wastes from various industries, into ready-to-eat extrudates, changes their structure and therefore affects their physical properties. The study explored the impact of varying levels of tomato pomace (ranging from 0% to 20%), moisture content in the mixture (ranging from 14.5% to 21.4% on a wet basis), and screw speed (ranging from 156 to 224 rpm) on the hardness of corn extrudates, as well as on parameters such as the number of pores, pore area, average pore size, and pore circularity. It was observed that, the inclusion of tomato pomace increases the hardness of the extrudates by decreasing the average pore size. On the other hand, the average pore size increases, and the hardness decreases with the increase of the screw speed. It was also observed that the higher initial moisture content of the mixtures increases the hardness and results in a more porous structure in the extruded products. The results show that the amount of tomato pomace and the process parameters significantly influence the structure of the extrudates.

Structural optimization study on porous transport layers of sintered titanium for polymer electrolyte membrane electrolyzers

An effective way to improve the performance of polymer electrolyte membrane (PEM) electrolyzers is to optimize the structural design of porous transport layers. This paper uses mirco-computed tomography (μ-CT) to study the three-dimensional microstructure distribution characteristics of commercial sintered titanium powder-based porous transport layers (PTL). A three-dimensional PTLs model with different porosity, pore diameter and thickness was established by Stochastic reconstruction model method. In addition, lattice Boltzmann method is used to study the influence of PTL structural parameters and single-phase permeability. The results show that the large compression thickness not only can significantly improve the PTL single-phase permeability, but also has little effect on the interface contact area. In addition, an increase in pore size and porosity will increase the transport performance while reducing interface contact. It is recommended that the average pore size of PTL should be greater than 10 μm, and the porosity should be greater than 30%. This work can be used to guide the preparation technology of PTL in order to improve the performance of PEM electrolyzer.

Comparison studies: The aging character of mask melt blown layers, polypropylene, and polyethylene terephthalate and their adsorption behavior for tetracycline hydrochloride

Melt-blown layer as a crucial component in medical surgical masks could release microplastics (MPs) into the environment after discarding. This study investigated the aging characteristics of the mask melt-blown layer, polypropylene (PP) and polyethene terephthalate (PET) MPs, as well as compared the adsorption capacity of tetracycline hydrochloride (TCH) on the virgin and aged MPs to gain adsorption mechanism. The carbonyl index (CI) index and two-dimensional correlation spectroscopy (2D-COS) analysis showed that the melt blown layer had the lower degree of aging than PP. Compared with the virgin PP and PET, the main reason for the lowest adsorption capacity of TCH on the virgin melt blown layer was that its unique dense microchannel structure led to the strongest hydrophobicity. The virgin PP and PET which had different chemical structures exhibited similar adsorption capacity of TCH. The adsorption of TCH on the MPs was physisorption, which was both controlled by diffusion, partitioning interaction and pore filling. The increase in the adsorption capacity of TCH on the aging MPs was attributed to the increase of hydrophilicity, pore size and specific surface area. In addition, the influence of environmental factors on the adsorption of TCH were discussed. Allover, this research provided comprehensive insights into the enrichment behavior associated with mask melt-blown materials in aquatic environments, and offered valuable data to support the investigation of the desorption behavior between MPs and antibiotics on organisms.

Effect of Ligand Aromaticity on Cyclohexane and Benzene Sorption in IRMOFs: A Computational Study.

A series of four isoreticular MOFs (IRMOF-1, -10, -14, and -16) were selected for a computational investigation of the effect of ligand aromaticity on the adsorption capacity of an aromatic VOC (benzene) compared to its nonaromatic analog (cyclohexane). The affinity of the adsorbates was evaluated by calculating Henry's constants and adsorption enthalpies. It has been evidenced that while KH values decrease with ligand elongation (IRMOF-10 and -16), inserting a pyrene core into the MOF structure (IRMOF-14) increases both the cyclohexane and benzene adsorption efficiency by ∼290 and 54%, respectively. To elucidate host-guest interactions, we sought to locate preferential adsorption sites in MOF structures for the two VOCs studied by using the GCMC method. It appears that benzene interacts with the metal center (Zn4O clusters) and most of the ligand while cyclohexane tends to localize preferentially only near the Zn4O clusters. Coadsorption isotherms (equimolar mixture of benzene and cyclohexane) demonstrated the preferential adsorption of cyclohexane due to the stronger affinity for the MOF structure. On the other hand, for other isoreticular structures, the ligand elongation leads to a shift of the adsorption curve of cyclohexane caused by pore size increase and therefore less interactions with the walls. This phenomenon is counterbalanced in the case of IRMOF-14 due to stronger interactions between the cyclohexane and pyrene groups. The present results thus open perspectives in the design of promising MOF candidates for high-performing separation and sorption/detection of hydrocarbon VOCs.