Effective Pore Research Articles

Synthesis of a 3D Porous Multicomponent Bioceramic Scaffold

In this study, 3D porous multicomponent bioceramic scaffolds were fabricated. Hydroxyapatite (HA) and carbonate-substituted hydroxyapatite (CHA) synthesized from Asian moon scallop shell (Amusium pleuronectes) served as the bioceramics, whereas alginate and chitosan served as the polymeric components. The study was focused on determining whether the presence of polyvinyl alcohol (PVA) in the scaffold exerted an impact. When PVA was not included, the morphological examination revealed that the samples exhibited porous structures characterized by effective pore interconnectivity and a substantial pore size. X-ray diffraction and scanning electron microscopic analyses indicated that the inclusion of PVA led to a decrease in the crystallinity, pore size, and porosity of the scaffolds. Those containing PVA exhibited porosity levels in the range of 56%–60%, and pore sizes ranged from 42 to 90 µm. These properties may provide advantages for the scaffold with respect to the ability for cell migration and cell attachment, thus enhancing new bone formation. Moreover, the compositions of HA and chemically modified HA (CHA) within the scaffold influenced the crystallinity and uniformity of the scaffold morphology. This finding suggests the potential for crafting a customized porous bioceramic scaffold based on specific compositions.

Adsorption of stable and labile emerging pollutants on activated carbon: degradation and mass transfer kinetic study

The design of adsorption processes for pharmaceuticals removal depends not only on the adsorption equilibrium but also on the mass transfer and adsorbate stability, being a problem still not solved the case of degradation products. By selecting different stable (amoxicillin, ciprofloxacin, carbamazepine and ibuprofen) and labile micropollutants (omeprazole) as case studies emerging pollutants, we have quantitatively analysed these effects on activated carbon. For stable compounds, the experimental data were fitted to equilibrium models to obtain information about the different adsorption mechanism depending on the characteristics of the molecules. Mass transfer effects were analysed for all the adsorbates, observing the control of intraparticle pore diffusion mechanism, since the effective pore diffusion coefficient is in the range from 10–8 to 10–10 cm2 h−1. As far as omeprazole is concerned, a kinetic model is proposed for predicting its degradation, identifying the reversibility of several degradation steps. The overall adsorption of OMP and derivates is calculated, observing the pore diffusion is considered as the rate-limiting step. For the first time, a combined model considering the chemical degradation and the adsorption of the degradation products is proposed and experimentally validated. This represents an important step in the modelling of processes leading to the purification of water from this type of pollutant.

Water distribution in pore systems and its influences on gas-bearing property of deep shale: A case study of the Longmaxi Formation in the Luzhou area, southern Sichuan Basin

The deeply-buried (>3500 m) Longmaxi Formation (LMX) shale in the southern Sichuan Basin, China, has become an attractive target for shale gas exploration owing to its huge resource potential. Exploration shows that the deep shale has a wide range of gas-in-place (GIP) contents, with variable gas yields, but the reason remains unclear, especially the impact of pore water on gas-bearing property lacks systematic research. In the present study, a suite of deep LMX shale samples was collected from the well FB1 in the Luzhou area of the southern Sichuan Basin, and techniques such as the pore water content measurements, low-pressure gas (CO2 and N2) adsorption and high-pressure methane adsorption experiments of the moist and dry samples were employed to investigate the distribution of water in the nanopores and its effects on the gas-bearing property. The results show that the deep shale is characterized by a high water content, with a high water saturation (average up to 69.80%), and the water occurs in both the inorganic and organic pores. The water reduces the effective specific surface area and pore volume of the shale averagely by 79.01% and 22.56%. Consequently, the water results in the decrease of methane adsorption capacity averagely by 45.13%. The GIP content models of two typical shale samples indicate that their total gas content is < 3 m3/t under the actual conditions, without development potential, and it will increase significantly to >3 m3/t with decreasing water saturation to <40–50%, especially under overpressure conditions. The gas-bearing property of deep LMX shale reservoirs in the complex faulted zones or structural-complex zones would mainly depend on the pore water content except for the properties of shale itself (e.g., maturity, TOC content, mineral composition, porosity and pore structure).

Highly selective methane sensing based on enhanced dual sieving effects by ZnO/Pd@Co node-replaced ZIF-8 nanorods

Highly selective methane sensing remains a formidable challenge in the field of metal oxide semiconductor (MOS)-based gas sensors. To address this issue, zeolitic imidazolate framework (ZIF) modulation is considered as an effective approach because of its pore size sieving and polarity sieving effects. In this work, core-shell ZnO/Pd@Co node-replaced ZIF-8 (ZIF-8/67) nanorods were synthesized by self-sacrificial template method, followed by post-synthetic modification of ZIF-8. When the replacement ratio of Co nodes reached 12.4%, ZnO/Pd@ZIF-8/67 exhibited a response of 12.2% to 500 ppm CH4 at 210°C but no response to 50 ppm CO, 50 ppm NH3 and 5 ppm NO2, showing excellent selectivity. By limiting rotational freedom of 2-methylimidazole, Co node replacement decreased the effective pore size from 4.0 to 4.2 Å to 3.8–4.0 Å and hindered the diffusion of NO2 with the dynamic diameter of 4.5 Å, thus enhancing the pore size sieving effect. Moreover, polarity sieving effect is also enhanced due to the favourable adsorption of polar CO (3.76 Å) and NH3 (2.6 Å) by ZIF. Therefore, the selectivity of nonpolar CH4 (3.8 Å) was improved. This work provides a new strategy for reasonably controlling and modulating the ZIF structure to achieve high selectivity in MOS-based sensors.

The amine-functionalized alumina captures CO2 directly from the ambient air in the rotating adsorption bed

Global warming presents formidable challenges, prompting the exploration of Direct Air Capture (DAC) as a promising solution. This study employed the ultrasonic impregnation method to load polyethyleneimine (PEI) onto cost-effective millimeter-sized spherical γ-Al2O3 microspheres, thereby preparing an efficient amine-modified adsorbent. Characterization reveals a uniform dispersion of PEI, resulting in an adsorbent with an effective pore structure, enhancing CO2 diffusion. The adsorption experiment combines DAC with high gravity technology, best conditions at a PEI load of 16.37%, high gravity factor of 2.67, and gas flow rate of 30 L/min. Under these conditions, an impressive adsorption capacity of 41.75 mg/g was achieved, marking an increase of 12.11 mg/g compared to the traditional fixed-bed method. The amine efficiency also reaches 0.25. The Freundlich model outperforms the Langmuir model in fitting isotherm curves, suggesting that the experimental data align with the characteristics of a heterogeneous surface and multilayer adsorption. The fitting results of kinetic models further show that RAB's adsorption rate constant has a significantly better fitting value compared to traditional fixed bed methods. The research provides valuable insights for the application and development of DAC technology, enabling new possibilities for future carbon capture and emission reduction efforts.

Relating permeability and electrical conductivity in partially saturated porous media by means of the Johnson–Koplik–Schwartz characteristic length

SUMMARY In this work, we revisit the seminal concept of Johnson–Koplik–Schwartz (JKS) length Λ, that is a characteristic length representing an effective pore size which controls various transport-related properties of porous media, such as, the permeability and the electrical conductivity. We present a novel closed-form equation that predicts the behaviour of Λ in partially saturated media, for different saturation states. Using previous models in the literature that predict the intrinsic and relative electrical conductivities under partially saturated conditions, we infer the JKS length Λ and the electrical formation factor F as functions of water saturation and properties associated with the pore-size distribution of the probed porous medium. The proposed method permits to estimate the effective permeability and the relative permeability directly from electrical conductivity measurements, thus opening new-avenues for the remote characterization of partially saturated media. We believe that this new model will prove useful for various characterization and modelling applications from reservoir (CO2 or hydrogen storage) to vadose zone studies.

Impact of CO2 sequestration on pressure systems in saline aquifer: Simulation of differential pressure evolution in the caprock-reservoir

CO2 sequestration in the saline aquifer is one of the most promising means of geological sequestration, and the realization of safe CO2 sequestration without leakage is the common goal of sequestration projects. Mature continental sedimentary basins typically have a long drilling and production history, and several wellbores inevitably penetrate the saline aquifer. These wellbores have been identified as risky locations for CO2 leakage. Scale-up CO2 injection can cause large-scale perturbations to the saline aquifer pressure system, affecting the sealing integrity of wells within the sequestration site. Considering that differential pressure is a key driver of wellbore leakage, this paper establishes and validates a three-dimensional cap-reservoir model to simulate the evolution of the differential pressure between the cap-reservoir due to CO2 sequestration. The simulation results show significant differences in the magnitude and rate of pressure buildup in the cap and reservoir during injection and in the rate of overpressure dissipation after stopping injection. These differences caused the dynamic evolution of the interlayer pressure difference. They formed peaks in the injection and stopping stages, and the peak in the injection stage was higher than in the stopping stage. The peak decreases as an exponential function with increasing distance from the injection well. In the constant rate injection mode, the peak rises linearly with increasing injection rate, and the effect of injection temperature on the peak can be neglected. A sensitivity analysis of reservoir hydrogeological parameters was done. From the perspective of controlling differential pressure, an ideal saline aquifer should be characterized by deep burial, low salinity, high permeability, and large effective pore space. This study is significant for CO2 sequestration site optimization and CO2 leakage risk control.

Pore structure characteristics and leaching mechanism of Cu and Cr in sustainable porous ceramisite produced from contaminated soil and biomass waste

Contaminated soil (CS) and biomass waste are potential resources. Their secure, scale, resource, and high-value utilization will bring significant socio-economic benefits. In present work, the basic properties, crystalline phases, microstructure and leaching behavior of porous ceramisite (PC) via CS and biomass waste were investigated systematically. The link of pore structure characteristics with leaching behavior of Cu and Cr was revealed. The environmental and economic benefits were also assessed. The results showed that the addition of 5∼15% pore-forming agent (carbon powder or biomass waste) made the matrix looser and the leaching amounts of heavy metals increased. However, the heavy metals leaching amounts was still lower than the critical limits of nonhazardous materials with immobilization rates higher than 97.5%. The leaching mechanism of Cu in the PC was controlled by initial wash-off, diffusion and depletion. The time period of the depletion dominated leaching is prolonged with increasing porosity. The leaching mechanism of Cr in the PC was mainly initial wash-off and depletion. The wash-off dominated the total heavy metal leaching amount, accounted for more than 80% of the total leaching amount. The leaching of Cu and Cr showed a positive correlation with (effective) pore volume of pores large than 1 μm, while demonstrating a negative correlation with the fractal dimension. The economic benefits of PC throughout the production process were analyzed, which showed that the production of PC using CS and biomass waste could eliminate raw material costs and could be subsidized by the government. This study provides an idea for the 100% utilization of CS and biomass waste as well as theoretical support for the disposal of solid waste.

Experimental study on the Klinkenberg effect for gas permeability in carboniferous shales, Eastern Qaidam Basin, China

It is crucial to understand the conditions and influencing mechanisms of shale gas slip effect for predicting the productivity of shale gas reservoirs. This study focuses on the Carboniferous Hurleg Formation shales in the eastern Qaidam Basin and conducts gas permeability tests using different gases (He/N2), as well as geochemical and pore-structure tests. The slip behavior of different gases in micro- and nanopores as well as the anisotropy of gas permeability were analyzed and discussed. The results show that helium permeability is 1.81–3.56 times higher than nitrogen permeability, with a greater difference at lower pore pressures. These permeability differences are attributed to variations in gas molecule size and slip effects. Specifically, the slip effect of helium gas has a greater contribution to permeability at lower pore pressures, with a helium slip factor averaging 2.79 times that of nitrogen. The effective pore size of shale, calculated based on the helium slip factor, is 0.74 to 1.51 times larger than when nitrogen is used, with an average of 1.67 times. Helium molecules have smaller diameters and longer average molecular free paths, resulting in a more pronounced slip effect compared to nitrogen. While helium does not adsorb, nitrogen exhibits some adsorption, causing radial expansion during gas penetration. Furthermore, when testing with different gases, the horizontal permeability (S043∥; S052∥) is higher than the vertical permeability (S043⊥; S052⊥). The anisotropy of permeability is controlled by the pore system formed by the arrangement and combination of minerals. Calcium-rich samples (S052) tend to exhibit higher anisotropy compared to calcite-rich samples (S043). The effective pore size in the vertical sample is larger than that in the parallel sample, and the gas slip effect is significantly greater in the vertical sample. These findings provide valuable data for future studies on shale gas slip effects and productivity prediction.

In situ stress prediction method for decoupled overburden pressure under tectonic constraints

Abstract The prediction of in situ stress based on azimuthal seismic data has extensive use in horizon crushability evaluation. Nonetheless, existing in situ stress seismic prediction models do not consider overburden pressure and tectonic strain, which limit the prediction accuracy. To this end, we propose a decoupled overburden pressure in situ stress prediction method under tectonic constraints. The key to this method is to consider that the overburden pressure could act on the rock skeleton and pore fluid, i.e. generating effective pressure and pore pressure; the pore pressure can be estimated using Eaton's method, and then the effective stress can be obtained. The relationship between tectonic strain and effective pressure is constructed based on Hooke's law, where tectonic strain can be calculated from curvature attributes extracted from seismic data. Introducing pore pressure and deriving a model for calculating the maximum and minimum horizontal stresses and the difference in horizontal stress ratio for orthotropic media (OA). When the Thomson anisotropy parameters and the pore pressure are neglected, the proposed model can be degraded to a conventional horizontal transverse isotropy medium in situ stress prediction model, which proves the validity of the model. The results of sensitivity analysis experiments affirm the need to decouple overburden pressure and account for tectonic strain when predicting in situ stress reasonably. Finally, single-well and azimuthal seismic prediction were carried out by using the a priori information from well logging and seismic data.

Bioinspired cell membrane-based nanofiltration membranes with hierarchical pore channels for fast molecular separation

Owing to intrinsic perm-selectivity, cell membranes have attracted considerable attention in the field of biomimetic membranes. Herein, largest possible cell membranes of E.coli were prepared and then used as two-dimensional (2D) materials to fabricate high-performance nanofiltration (NF) membranes. The structure parameters of the selective layer of the E.coli-NF membrane could be finely tailored through the loading mass of cell membranes and the applied pressure during vacuum filtration. The E.coli-NF membrane exhibited a high rejection towards dyes (98.5%, brilliant blue R), antibiotics (91.1%, erythromycin), and divalent ions (64.8%, sodium sulfate). The membrane effective pore size was found to be significantly smaller than the interlayer spacing because of the small intrinsic nanochannels inside the E.coli cell membranes, which is distinct from GO and MXene-based 2D membranes. Moreover, the membrane water permeance was 52.6 L m−2 h−1 bar−1, higher than that of most of the reported 2D materials-based NF membranes. The E.coli-NF membrane exhibited the typical separation behavior of the negatively charged NF membranes governed by Donnan effect and size exclusion. This work gives some insights into the fabrication of the selective membranes using cell membranes as 2D materials with intrinsic nanochannels and fruitful choices in nature.

Advancing Molecular Sieving via Å-Scale Pore Tuning in Bottom-Up Graphene Synthesis.

Porous graphene films are attractive as a gas separation membrane given that the selective layer can be just one atom thick, allowing high-flux separation. A favorable aspect of porous graphene is that the pore size, essentially gaps created by lattice defects, can be tuned. While this has been demonstrated for postsynthetic, top-down pore etching in graphene, it does not exist in the more scalable, bottom-up synthesis of porous graphene. Inspired by the mechanism of precipitation-based synthesis of porous graphene over catalytic nickel foil, we herein conceive an extremely simple way to tune the pore size. This is implemented by increasing the cooling rate by over 100-fold from -1 °C min-1 to over -5 °C s-1. Rapid cooling restricts carbon diffusion, resulting in a higher availability of dissolved carbon for precipitation, as evidenced by quantitative carbon-diffusion simulation, measurement of carbon concentration as a function of nickel depth, and imaging of the graphene nanostructure. The resulting enhanced grain (inter)growth reduces the effective pore size which leads to an increase of the H2/CH4 separation factor from 6.2 up to 53.3.

Bone cell response to additively manufactured 3D micro-architectures with controlled Poisson's ratio: Auxetic vs. non-auxetic meta-biomaterials

The Poisson's ratio and elastic modulus are two parameters determining the elastic behavior of biomaterials. While the effects of elastic modulus on the cell response is widely studied, very little is known regarding the effects of the Poisson's ratio. The micro-architecture of meta-biomaterials determines not only the Poisson's ratio but also several other parameters that also influence cell response, such as porosity, pore size, and effective elastic modulus. It is, therefore, very challenging to isolate the effects of the Poisson's ratio from those of other micro-architectural parameters. Here, we computationally design meta-biomaterials with controlled Poisson's ratios, ranging between -0.74 and +0.74, while maintaining consistent porosity, pore size, and effective elastic modulus. The 3D meta-biomaterials were additively manufactured at the micro-scale using two-photon polymerization (2PP), and were mechanically evaluated at the meso‑scale. The response of murine preosteoblasts to these meta-biomaterials was then studied using in vitro cell culture models. Meta-biomaterials with positive Poisson's ratios resulted in higher metabolic activity than those with negative values. The cells could attach and infiltrate all meta-biomaterials from the bottom to the top, fully covering the scaffolds after 17 days of culture. Interestingly, the meta-biomaterials exhibited different cell-induced deformations (e.g., shrinkage or local bending) as observed via scanning electron microscopy. The outcomes of osteogenic differentiation (i.e., Runx2 immunofluorescent staining) and matrix mineralization (i.e., Alizarin red staining) assays indicated the significant potential impact of these meta-biomaterials in the field of bone tissue engineering, paving the way for the development of advanced bone meta-implants. Statement of significanceWe studied the influence of Poisson's ratio on bone cell response in meta-biomaterials. While elastic modulus effects are well-studied, the impact of Poisson's ratio, especially negative values found in architected biomaterials, remains largely unexplored. The complexity arises from intertwined micro-architectural parameters, such as porosity and elastic modulus, making it challenging to isolate the Poisson's ratio. To overcome this limitation, this study employed rational computational design to create meta-biomaterials with controlled Poisson's ratios, alongside consistent effective elastic modulus, porosity, and pore size. The study reveals that two-photon polymerized 3D meta-biomaterials with positive Poisson's ratios displayed higher metabolic activity, while all the developed meta-biomaterials supported osteogenic differentiation of preosteoblasts as well as matrix mineralization. The outcomes pave the way for the development of advanced 3D bone tissue models and meta-implants.

Dynamic of CO2 adsorption in a fixed bed of microporous and mesoporous activated carbon impregnated with sodium hydroxide and the application of response surface methodology (RSM) for determining optimal adsorption conditions.

Microporous and mesoporous activated carbon produced from longan-seed biomass were impregnated with NaOH and used to capture CO2 from a simulated flue gas in a fixed-bed column. The process variables that were studied included types of activated carbon as characterized by the volume ratio of micropores and mesopores (Vmic/Vmes), adsorption temperature, NaOH loading, gas feed rate and the adsorbent amount. All five process variables affected the two important breakthrough parameters, namely the breakthrough time (tB) and CO2 adsorption capacity at breakthrough time (qB), with different trends and degrees. However, it was only the NaOH loading that showed a characteristic of an optimum loading that provided the maximum of the breakthrough parameters. It was found that an approximate 45% increase in the adsorbed amount of CO2 could be achieved with the activated carbon impregnated with around 1 weight % NaOH solution as compared to the case of the non-impregnated carbon. The response surface methodology (RSM) was applied to develop the correlations for both tB and qB and the maximum predicted qB of 33.58mg/g was derived at the NaOH loading of 76.5mg/g carbon, Vmic/Vmes of 2.83, adsorption temperature of 20°C, gas feed rate of 156kg/m2-h and adsorbent amount of 51kg/m2 of column cross-section area. The Klinkenberg's breakthrough model was able to describe the CO2 breakthrough curves reasonably well for all the tested conditions. The analysis of the two model parameters, the affinity constant (K) and the effective pore diffusivity (De), revealed that the optimum Vmic/Vmes that provided the maximum K value was around 2.90, corresponding to the activated carbon that contains 74% and 26% by volume of micropores and mesopores, respectively. The proper volume ratio of micropores and mesopores along with alkali addition into activated carbon can be effectively used for maximizing CO2 adsorption in a fixed-bed adsorption system.

Biomimetic construction of smart nanochannels in covalent organic framework membranes for efficient ion separation

Smart nanochannels can regulate ion transport behavior by external stimulus and display precise ion selectivity in biological membrane systems, but constructing artificial membranes with responsive and tunable channel remains a severe challenge. Herein, smart covalent organic framework (COF) membranes decorated with photo-responsive azobenzene derivatives (COF-Azo) were fabricated by a biomimetic nanochannel modulation (BNM) strategy, endowing membranes with charged and switchable sub-nanochannels. Under different wavelength of light, the smart COF-Azo membranes simultaneously exhibited outstanding mono/monovalent and mono/divalent ion selectivity (K+/Li+ ideal selectivity of 17.9 and Li+/Mg2+ ideal selectivity of 24.9) via closing and opening channels. The conversion of effective pore size at angstrom level is realized by photoisomerization of azobenzene. After several photoswitch cycles, the smart membranes still maintained K+/Li+ selectivity of 6.1 and Li+/Mg2+ selectivity of 20.7 in mixed salt solution, exhibiting great potentials in lithium extraction. This work may blaze a trail in constructing photo-responsive nanochannel membranes for energy-efficient ion separation.

Increase in the effective viscosity of polyethylene under extreme nanoconfinement.

Understanding polymer transport in nanopores is crucial for optimizing heterogeneously catalyzed processes in polymer upcycling and fabricating high-performance nanocomposite films and membranes. Although confined polymer dynamics have been extensively studied, the behavior of polyethylene (PE)-the most widely used commodity polymer-in pores smaller than 20nm remains largely unexplored. We investigate the effects of extreme nanoconfinement on PE transport using capillary rise infiltration in silica nanoparticle packings with average pore radii ranging from ∼1 to ∼9nm. Using in situ ellipsometry and the Lucas-Washburn model, we discover a previously unknown inverse relationship between effective viscosity (ηeff) and average pore radius (Rpore). Additonally, we determine that PE transport under these extreme conditions is primarily governed by physical confinement, rather than pore surface chemistry. We refine an existing theory to provide a generalized formalism to describe the polymer transport dynamics over a wide range of pore radii (from 1nm and larger). Our results offer valuable insights for optimizing catalyst supports in polymer upcycling and improving infiltration processes for nanocomposite fabrication.

High-flux and chlorine-resistant nanofiltration membrane fabricated via phase inversion using polysulfone-b-polyglycerol hyperbranched block copolymer

The nanofiltration (NF) membranes having excellent chlorine resistance and sufficient perm-selectivity are highly desired in drinking water treatment and other applications. Herein, a novel block copolymer NF membrane with superior chlorine resistance, especially high water permeance was prepared via phase inversion, using a tailor-made polysulfone-block-hyperbranched polyglycerol (PSf-b-hPG) material. The fabricated PSf-b-hPG NF membrane shows an extremely thin separation layer with a thickness of around 80 nm and a high overall porosity of 65 %, thanks to the structural advantage of hyperbranched hydrophilic hPG segments and the unique feature of the PSf-b-hPG casting solution of possessing a very low viscosity at a high solid content. The membrane exhibits an effective pore diameter of 1.6 nm, and the molecular weight cut-off (MWCO) was around 4 kDa. The membrane displayed extremely high pure water permeance of 34 LMH/bar as well as a satisfactory Na2SO4 rejection of 74 %. Moreover, the membrane exhibits superior chlorine resistance with no change in separation performance when challenged with 36,000 ppm∙h chlorination intensity and also maintains a stable Na2SO4 rejection and water permeance during the 14 h NF test. Our results suggest the NF membrane prepared by PSf-b-hPG has superior chlorine resistance and high water permeance, and is capable of efficiently removing sulfate from drinking water or others.

Self-assembled dendrimer polyamide nanofilms with enhanced effective pore area for ion separation

Membrane technology using well-defined pore structure can achieve high ion purity and recovery. However, fine-tuning the inner pore structure of the separation nanofilm to be uniform and enhance the effective pore area is still challenging. Here, we report dendrimers with different peripheral groups that preferentially self-assemble in aqueous-phase amine solution to facilitate the formation of polyamide nanofilms with a well-defined effective pore range and uniform pore structure. The high permeabilities are maintained by forming asymmetric hollow nanostripe nanofilms, and their well-designed ion effective separation pore ranges show an enhancement, rationalized by molecular simulation. The self-assembled dendrimer polyamide membrane provides Cl–/SO42– selectivity more than 17 times that of its pristine polyamide counterparts, increasing from 167.9 to 2883.0. Furthermore, the designed membranes achieve higher Li purity and Li recovery compared to current state-of-the-art membranes. Such an approach provides a scalable strategy to fine-tune subnanometre structures in ion separation nanofilms.

Novel for the resistance welding of laminated wire mesh microgroove composite wicks with enhanced capillary performance

The efficient operation of micro heat pipes (MHPs) requires evaporation and rapid condensation of the working liquid reflux to the heat source, and the internal wick structures play a crucial role. With the advantages of high porosity, good flexibility, and low thickness, mesh is ideal for ultrathin thermal management systems, especially acting as wicks in MHPs. This study proposes a novel method of fabricating resistance-welded laminated mesh microgroove composite wick structures; this is different from the earlier composite wick structure that first processed microgrooves on a flat substrate and then laid the mesh for vacuum sintering. The new composite wick structures were fabricated by the resistance welding of laminated meshes, soaking them in resin, and laser processing them with microgrooves after solidification, which exhibited superhydrophilicity. The capillary rise experiment was used to test the capillary performance of the composite wick structure, and the ΔPcap·K value was used as an index to evaluate the capillary performance of samples. The results showed that the effective pore size gradually decreased, and the capillary performance gradually improved with an increase in the number of mesh welding layers. Compared with the single-layer mesh, the capillary height of the four-layer welded laminated mesh was increased by approximately 66.94 %. By modifying the laminated screen with resin soaking and processing microgrooves, forming porous microstructures on the sidewalls and bottom of the microgrooves, the capillary performance significantly improved again, with a maximum capillary height of 83.23 mm that was increased by approximately 394.83 % and 196.4 % than that of the single-layer screen and the four-layer laminated screen before modification, respectively, and the ΔPcap·K values were increased by approximately 157.38 % and 49.69 %, respectively. This study provides a new ideal for the fabrication of composite wicks for enhancing the thermal performance of MHPs.

Three in One: Engineering MOF Channels via Coordinated Water Arrays for Regulated Separation of Alkanes and Alkenes

Purifying alkenes (mainly ethylene and propylene) by removing their corresponding alkanes is crucial yet challenging in the chemical industry. Selective physisorption shows promise for effective separation but demands precise pore...