Porous Properties Research Articles

Advancements in renewable energy: Achieving milder reaction conditions in biodiesel synthesis from green seed canola oil with pristine ZIF-8

This study explores the enhancement of reaction conditions for biodiesel production from green seed canola oil through the methanolysis reaction using pristine ZIF-8 as a catalyst. The research focused on the effects of varying the methanol-to-oil molar ratio, temperature, and reaction time as well as their combined effects on biodiesel yield. To analyze these factors, Response Surface Methodology (RSM) paired with Central Composite Design (CCD) was employed. The quadratic model was identified as the best fit for the experimental data, evidenced by a high determination coefficient (R²) of 0.99, with all model parameters proving significant. A comprehensive characterization of the catalyst was conducted using various techniques. The surface and pore properties were examined using N2 adsorption-desorption measurements. X-ray diffractometry (XRD) was employed for structural analysis, while X-ray photoelectron spectroscopy (XPS) presented the binding information of the sample. Fourier transform infrared spectroscopy (FT-IR) provided insights into the functional groups present. Thermal gravimetric analysis (TGA) assessed the thermal stability of the catalyst. Results revealed that ZIF-8 significantly improved biodiesel production, with optimal conditions identified at a reaction temperature of 160 °C, a duration of 2.5 h, and methanol to oil (M/O) molar ratio of 26, resulting in a biodiesel yield of 85 %. This yield is close to the predicted value, demonstrating the reliability of the developed model. The kinetic analysis was performed under optimal reaction conditions. From this, the activation energy (Ea) and the pre-exponential factor (A) were obtained to be 14.5 kJ/mol and 3.4×10−7 min−1, respectively. The use of pristine ZIF-8 in biodiesel production from a low-quality and cheap oil offers a more efficient and milder reaction conditions, with potential for significant reductions in production costs and environmental impact.

Effect of layered fertilizer strategies on rapeseed (Brassica napus L.) productivity and soil macropore characteristics under mechanical direct-sowing

Layered fertilization parameters affects crop root system configuration and growth distribution, which in turn affects soil pore properties and aggregate structure. Therefore, understanding the spatial distribution of the root system and soil pore space is helpful in choosing a reasonable fertilization ratio in production practice, which ensures high and stable crop yields and at the same time improves fertilizer utilization and soil health. Albeit the impact of layered fertilization ratio at varied rates on soil pore characteristics in the soil profile at a microscale level remains limited. This study quantifies the impacts of layered fertilization ratio under on rapeseed root distribution and soil pore characteristics using the root analysis system and X-ray computed tomography (XCT). A new fertilization pattern that shallow-deep layer synchronized mechanical sowing was using, rotary tillage mixed fertilization in the shallow layer and 10 cm side-deep band fertilization in the deeper layer. It set five ratios of fertilizer amounts between shallow and deep layers as 0:4 (FD), 1:3 (FL), 2:2 (FM), 3:1 (FH), and 4:0 (F0), with non-fertilization (CK) as the control treatment. The results indicated that layered fertilization effectively improved the rape root conformation and spatial distribution, significantly increased total soil porosity and moisture content, and reduced soil bulk density and resistance (P < 0.05). Additionally, root configuration is closely related to soil pore structure and crop yield. Notably, compared with other treatments, the macroscopic porosity, equivalent pore diameter, hydraulic radius and roundness of FM treatment are significantly improved, and it effectively improves the yield and quality of rapeseed. Correlation analysis showed that the root system configuration parameters were negatively correlated with soil bulk density and resistance but positively correlated with soil moisture content, and macropore morphology parameters and rapeseed yield. Our study demonstrate that layered fertilization can improved rape growth and soil macropore porosity, but its effect depends on good tillage macropore characteristics and distribution created by reasonable fertilization ratio, which provided a theoretical basis for high-yield, efficient, green, and sustainable mechanized direct-sowing production of rapeseed.

Mechanisms of Action Underlying Conductance-modifying Positive Allosteric Modulators of the NMDA Receptor.

NMDA receptors (NMDARs) are ionotropic glutamate receptors that mediate a slow, Ca2+-permeable component of fast excitatory neurotransmission. Modulation of NMDAR function has the potential for disease modification as NMDAR dysfunction has been implicated in neurodevelopment, neuropsychiatric, neurological, and neurodegenerative disorders. We recently described the thieno[2,3-d]pyrimidin-4-one (EU1622) class of positive allosteric modulators, including several potent and efficacious analogs. Here we have used electrophysiological recordings from Xenopus oocytes, HEK cells, and cultured cerebellar and cortical neurons to determine the mechanisms of action of a representative member of this class of modulator. EU1622-240 enhances current response to saturating agonist (doubling response amplitude at 0.2-0.5 µM), slows the deactivation time course following rapid removal of glutamate, increases open probability, enhances co-agonist potency, and reduces single channel conductance. We also show that EU1622-240 can transform NMDARs so that they can be opened when only glutamate or glycine is bound. EU1622-240-bound NMDARs channels activated by a single agonist (glutamate or glycine) open to a unique conductance level with different pore properties and Mg2+ sensitivity, in contrast to channels arising from activation of NMDARs with both co-agonists bound. These data demonstrate that previously hypothesized distinct gating steps can be controlled by glutamate and glycine binding and shows that the 1622-series modulators enable glutamate- or glycine-bound NMDARs to generate open conformations with different pore properties. The properties of this class of allosteric modulators present intriguing therapeutic opportunities for the modulation of circuit function. Significance Statement NMDA receptors are expressed throughout the CNS and are permeable to calcium. EU1622-240 increases open probability and agonist potency, while reducing single channel conductance and prolonging the deactivation time course. EU1622-240 allows NMDA receptor activation by the binding of one co-agonist (glycine or glutamate), which produces channels with distinct properties. Evaluation of this modulator provides insight into gating mechanisms and may lead to the development of new therapeutic strategies.

Reconstruction of reservoir rock using attention-based convolutional recurrent neural network

The digital reconstruction of reservoir rock or porous media is important as it enables us to visualize and explore their real internal structures. The reservoir rocks (such as sandstone and carbonate) contain both spatial and temporal characteristics, which pose a big challenge in their characterization through routine core analysis or x-ray microcomputer tomography. While x-ray micro-computed tomography gives us three-dimensional images of the porous media, it is often impossible to quantify the variability of the pore, grains, structure, and orientation experimentally. Recently, machine learning has successfully demonstrated the reconstruction ability of reservoir rock images or any porous media. These reservoir rock images are crucial for the digital characterization of the reservoir. We propose a novel algorithm consisting of the convolutional neural network, an attention mechanism, and a recurrent neural network for the reconstruction of reservoir rock or porous media images. The attention-based convolutional recurrent neural network (ACRNN) can reconstruct a representative sample of reservoir rocks. The reconstructed image quality was checked by comparing them with the original Parker sandstone, Leopard sandstone, carbonate shale, Berea sandstone, and sandy medium images. We evaluated the reconstruction by measuring pore and throat properties, two-point probability function, and structural similarity index. Results show that ACRNN can reconstruct reservoir rock or porous media of different scales with approximately the same geometrical, statistical, and topological parameters of the reservoir rock images. This deep learning method is computationally efficient, fast, and reliable for synthetic image realizations. The model was trained and validated on real images, and the reconstructed images showed excellent concordance with the real images having almost the same pore and grain structures. The deep learning-based digital rock reconstruction of reservoir rock or porous media images can aid in rapid image generation to better understand reservoir rock or subsurface formation.

Statistical Comparison between Pores and Sunspots during the Time Interval 2010–2023

To reveal the physical properties of pores and sunspots varying with solar cycle, we carried out a statistical comparison among pores, transitional sunspots, and mature sunspots using Solar Dynamics Observatory/Helioseismic and Magnetic Imager from 2010 April to 2023 July. The OTSU method and region-growing algorithm were combined to detect umbrae of 11,876 sunspots covering solar cycles 24 and 25. The relationships between umbral area, continuum intensity (I), line-of-sight (LOS) magnetic field strength (B los), and line-of-sight velocity (V los) of umbrae were investigated in detail. The main conclusions are as follows. (1) The steepness between the total magnetic flux and total area of transitional sunspots appears to be flattened in each phase of the observed solar cycles, and does not have a significant variation over the solar cycle. (2) For three groups of sunspots, the umbral physical parameters’ means and their correlations show only minor variations with the solar cycle, which are in error ranges. (3) As the mean umbral LOS magnetic field strength increases, the correlation of the umbral I–B los increases. The flattening of transitional sunspots in total area–total magnetic flux scatter is related to the evolution of sunspots itself, and may not correspond to the solar cycle. The umbral physical parameters and their correlations do not exhibit a discernible regularity over the solar cycle. Our analysis results contribute to a more comprehensive understanding of the dynamic processes of sunspot magnetic fields and give a new perspective on revealing the physical features of vertical magnetic flux tubes.

The novel incorporation of lignin-based systems for the preparation of antimicrobial cement composites

This paper, for the first time, presents a potential application of titanium(IV) oxide and silicon(IV) oxide combined with lignin through a solvent-free mechanical process as admixtures for cement composites. The designed TiO2–SiO2 (1:1 wt./wt.) hybrid materials mixed with lignin were extensively characterized using Fourier transform infrared spectroscopy (FTIR), electrokinetic potential analysis, thermal analysis (TGA/DTG), and porous structure properties. In addition, particle size distributions and scanning electron microscopy (SEM) were conducted to evaluate morphological and microstructural properties. In the next step, the effect of the TiO2–SiO2/lignin hybrid admixture on the workability, hydration process, microstructure, porosity, mechanical, and antimicrobial properties of the cement composites was evaluated. It was observed that appropriately designed hybrid systems based on lignin contributed to better workability, with an improvement of 25 mm, and reduced porosity of cement composites, decreasing from 14.4 % to 13.3 % in the most favorable sample. Additionally, a higher microstructure density was observed, and with increasing amounts of hybrid material admixture, the mechanical parameters also improved. In addition, the TiO2–SiO2/lignin hybrid systems had significant potential due to their high microbial purity, suggesting their effectiveness in minimizing microbial accumulation on surfaces. The final stage of analysis involved employing response surface methodology (RSM) to ascertain the optimum composition of cement composites. The results obtained indicate that the TiO2–SiO2/lignin admixtures are a promising approach for the valorization of lignin waste flows in the design of cement composites.

A new semi-analytical approach for nonlinear dynamic responses of functionally graded porous graphene platelet-reinforced circular plates and spherical shells

This paper presents the semi-analytical approach for nonlinear dynamic responses of porous graphene platelet-reinforced circular plates (CiPs) and spherical shells (SpSs) resting on the Pasternak foundation in thermal environment. The graphene platelets (GPLs) are distributed in the functionally graded (FG) distribution patterns and uniform distribution pattern through the CiP and SpS thickness direction. The governing equations of the GPL-reinforced structures subjected to time-dependent external pressure respected to the harmonic and linear functions of time are established based on the geometrically nonlinear higher-order shear deformation theory. A simple and effective semi-analytical solution for the considered problem is established using the Euler-Lagrange equations, and the damping viscosity of the foundation can be counted using the Rayleigh dispassion function. The Runge-Kutta method is employed to determine the dynamic responses of the GPL-reinforced structures, while the fundamental frequencies of free and linear vibration, and frequency-amplitude curves are obtained in explicit form. The numerical results obtained reveal that the GPL and porous distributions, geometrical and material properties can significantly affect the frequency-amplitude curves, and dynamic responses of harmonically loaded and linearly loaded structures, specially, the dynamic buckling phenomenon is clearly observable with the SpSs but not with the CiPs.

Modeling and Analysis of Droplet Evaporation at the Interface of a Coupled Free-Flow–Porous Medium System

AbstractEvaporation of droplets formed at the interface of a coupled free-flow–porous medium system enormously affects the exchange of mass, momentum, and energy between the two domains. In this work, we develop a model to describe multiple droplets’ evaporation at the interface, in which new sets of coupling conditions including the evaporating droplets are developed to describe the interactions between the free flow and the porous medium. Employing pore-network modeling to describe the porous medium, we take the exchanges occurring on the droplet–pore and droplet–free-flow interfaces into account. In this model, we describe the droplet evaporation as a diffusion-driven process, where vapor from the droplet surface diffuses into the surrounding free flow due to the concentration gradient. To validate the model, we compare the simulation results for the evaporation of a single droplet in a channel with experimental data, demonstrating that our model accurately describes the evaporation process. Then, we examine the impact of free-flow and porous medium properties on droplet evaporation. The results show that, among other factors, velocity and relative humidity in the free-flow domain, as well as pore temperature in the porous medium, play key roles in the droplet evaporation process.

Study of the effect of pore properties of microporous layer on water transport process in proton exchange membrane fuel cell

Aiming at the “water flooding” phenomenon inside the Gas Diffusion Layer (GDL) of the Proton Exchange Membrane Fuel Cell (PEMFC), this paper visualizes the effects of the pore properties and gradient structure of the microporous layer (MPL) on water transport. Specifically, we visualize the impact of pore properties and gradient structure on water transport. For this purpose, a liquid water capillary finger advancement visualization test platform is constructed to analyze the evolution of liquid water in the porous medium and reveal the effects of single porosity, single pore diameter, gradient porosity, and gradient pore diameter of the MPL on the liquid water transport. Moreover, the time of the non-wetting liquid touching the top, the maximum spreading length, and the residual volume in the MPL are analyzed to evaluate the drainage capacity. The results highlight that the microporous layer's smaller porosity and pore size could limit the interface's extended width between the microporous and gas diffusion layers. Additionally, the residual volume of non-wetting liquid is 21.6 % less in the case of φ = 0.3 than for φ = 0.45, and the residual volume of non-wetting liquid is 11.8 % less in the case of d = 0.82 mm compared to d = 2.45 mm. Furthermore, the residual volume of the microporous layer in the Catalyst layer (CL) side of the microporous layer is 11.8 % less than that in the case of d = 2.45 mm. Finally, we conclude that when the pore gradient law is opposite, it is unfavorable for liquid water discharge.

Improving the pore properties of porous aromatic frameworks in two aspects via partition strategy

Microporous solids are famous for their high surface area and pore size at the molecular scale, which are crucial for the applications of adsorption, separation and catalysis. An ideal porous solid would simultaneously have a high surface area and nanopores with the desired opening size. However, due to the uncontrollable reaction process of porous organic frameworks (POFs), the acquisition of such a solid is still technically limited. Herein, we reported a simple but platform-wide pore partition strategy to improve the porosity of porous aromatic frameworks (PAFs) in two aspects. This strategy was achieved by introducing a partition unit with flexible linkage to segment the original voids of PAFs into multiple micropore domains. The obtained partitioning PAFs have 130%-217% increments in surface area due to the creation of extra accessible surfaces while the pores are segmented into smaller ones. Notably, the partitioning PAFs showed significantly increased adsorption capacity for CO2 due to their improved surface area. At the same time, the narrowed pore size allowed selective capture of dye molecules by their size differences. Similar to their parent PAFs, the partitioning PAFs retained their high stability in harsh environments. A simple and universal pore partition strategy will be an important step in improving PAF porosity to desired functions.

Constructing 2D Porous ZnO Gas Sensors Based on Polyvinylpyrrolidone-Assisted Zn-MOF Nanosheets for NO2 Detection.

Two-dimensional (2D) ZnO nanomaterials are promising for gas sensing, because of their large surface area, abundant active sites, and rapid charge transfer. However, it is challenging to prepare 2D ZnO nanosheet gas sensors with high sensing performance, due to the tight interlayer stack and low adsorptive property of ZnO for NO2 molecules. Herein, we synthesized Zn-MOF nanosheets employing polyvinylpyrrolidone (PVP) as the structure-directing agent, further through pyrolysis of the Zn-MOF to obtain 2D ZnO nanosheet gas sensors. As anticipated, the 2D ZnO gas sensors exhibited high sensitivity and selectivity for NO2, and the optimal sample could achieve a response value of 162 at the working temperature of 160 °C, which is 10 times higher than that of pristine ZnO. Meanwhile, experimental and DFT results showed that PVP plays critical roles in the lateral lattice growth of 2D Zn-MOF nanosheets, while the existence of PVP makes the ZnO gas sensors with rich porous property and more oxygen vacancy after the pyrolysis process, which promoted the adsorption, activity, and surface reaction for NO2 molecules. It provides a new approach for the application of 2D ZnO nanosheets in the NO2 detection field.

Rice husk biochar is more effective in blocking the cadmium and lead accumulation in two Brassica vegetables grown on a contaminated field than sugarcane bagasse biochar.

Heavy metal-contaminated soil has a great impact on yield reduction of vegetable crops and soil microbial community destruction. Biochar-derived waste biomass is one of the most commonly applied soil conditioners in heavy metal-contaminated soil. Different heavy metal-contaminated soil added with suitable biochars represent an intriguing way of the safe production of crops. This study investigated the effects of two types of biochar [rice husk biochar (RHB) and sugarcane bagasse biochar (SBB)] on Cd and Pb accumulation in Shanghaiqing (SHQ, a variety of Brassica campestris L.) and Fengyou 737 (FY, a variety of Brassica napus), as well as on the soil microbial community, through a field experiment. RHB and SBB were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmet-Teller method. The results showed that RHB and SBB displayed the higher pH, cation exchange capacity and pore properties, and the addition of RHB and SBB enhanced soil pH and rhizosphere microorganisms promoting vegetables yield. RHB treatments were more effective than SBB in reducing upward transfer of Cd and Pb, blocking the accumulation of Cd and Pb in the edible parts of SHQ and FY, and decreasing soil Cd and Pb bioavailability. Additionally, RHB and SBB changed the composition of the rhizosphere soil microbial community. The application of biochar promoted the growth of ecologically beneficial bacteria (Nitrospira, Opitutus, and Gemmatimonas) and fungi (Mortierella and Holtermanniella), whereas reducing the enrichment of plant pathogenic fungi (Alternaria, Stagonosporopsis, Lectera, and Periconia) in rhizosphere soil. Our findings demonstrated that the application of RHB significantly reduces Cd and Pb accumulation in the edible parts by decreasing the soil Cd and Pb bioavailability and altering the rhizosphere microbial community composition in two Brassica vegetables grown on Cd/Pb-contaminated soils. Thus, the application of two biochar, especially RHB is a feasible strategy for the safe production of vegetable crops in Cd/Pb co-contaminated soils.

Porous biochar-driven innovative Cr(VI) reduction and resource recovery

Catalyst-mediated Cr(VI) reduction face significant challenges in by-product ion residues and catalyst cost. The development of low-cost catalysts and catalytic technologies with near-zero impurity introduction is therefore of great practical importance. This study developed a pristine biochar-mediated nanoconfinement strategy that facilitated the chemical reaction between oxalic acid (OA) and Cr(VI) with a stoichiometric ratio of 3.3:1. The method achieved the simultaneous Cr(VI) reduction and OA removal, and completed the chromium removal process with near-zero impurity introduction after a precipitation process. While traditional catalyst-mediated reduction relied on mechanisms of functional group or active sites, this study took a novel path by adopting a focus on pore size. The structure–activity relationship, and experimental design demonstrated the predominant role of porous properties in the reaction, thus proposing a nanoconfinement Cr(VI) reduction mechanism. Continuous flow results revealed a treatment capacity of 1750 mL/h for the complete removal of Cr(VI) from Cr electroplating rinse water. The effluent, precipitated with CaO, had 0.06 mg/L of total Cr and 0.56 mg/L of OA, while the precipitate, recovered as CaCr2O4, demonstrated a total Cr recovery efficiency of 90.4%. Compared to industrial Cr(VI) chemical reduction, this study minimizes impurity introduction to the catalytic system. This study explores an effective strategy for Cr(VI) reduction and Cr resource recovery using low-cost pristine biochar, and provides navigation for the removal and resource utilization of other heavy metals or radionuclides.

A new semi-analytic model for Stern-layer polarization in pore throats

SUMMARY To explain induced polarization, membrane polarization is often referred to as a relevant process taking place in granular media – particularly, when narrow pore throats are present. This polarization effect is based on the membrane-like behaviour of pore throats caused by the presence of an usually negative charge on the pore surface, that influences charge transport in the pore fluid. Existing analytical, 1D models describe the pore system as a series of cylindrical pores with different radii and lengths. The polarization response is calculated by solving the Poisson–Nernst–Planck system for the current densities of one single anion and one single cation species representing the charge transport in the electrolyte and the diffuse layer at the pore surface. To include charge transport in the Stern layer, cations in the Stern layer have so far simply been considered by increasing the concentration of the diffuse layer cations. As we know from numerical modelling, this approach fails to predict the polarization response when the Stern layer is significantly charged. Here, we present a new semi-analytical model that treats the Stern-layer cations as a separate ion species and allows the Stern layer to polarize individually. To validate our new model, we compare it to the previously used analytical model and numerical simulations for different relative charges in Stern- and diffuse layer. We also use electrostatic surface-complexation models for two mineral surfaces (quartz and montmorillonite) to simulate the response of real geologic material under varying chemical conditions. This work is a step forward for considering realistic pore properties in induced-polarization modelling.

Understanding the role of flux chamber configuration in the measurement of VOC emissions from porous media

The accurate quantification of volatile organic compound (VOC) emission rates from porous media to the air is a challenging problem, as measurements are affected by the chemical and physical characteristics of the porous media, and the operating parameters of the sampling device itself. The main objective of this study is to investigate how flux chamber (the most commonly used sampling device) configurations influence emission rate measurement from three selected porous media. Various parameters were studied, including sweep air flow rate, presence of a mixing fan, headspace volume and thickness of media. Controlled experiments focused on the behaviour of two VOCs commonly found in area sources: acetic acid and 1-butanol. Sweep gas flow rate emerged as the most influential factor, inducing turbulence and dilution over porous media surfaces and impacting emission rate measurements more significantly than headspace volume and fan installation. Variations in porous media properties also affected mass transfer, with emissions from coco coir showing higher mass transfer as its porosity and particle size facilitated gas transportation. While behaviour of acetic acid emission through the media supported the diffusion theory, emission of 1-butanol was affected by a combination of factors, highlighting the role of both diffusive and advective transport mechanisms. Understanding how flux chamber setups and porous media properties influence emission rates is crucial for accurately interpreting data. This knowledge also guides the design of studies, especially when investigating complex sources like biosolids and organic-amended soil.

Low cost Non freeze-drying construction strategy of cellulose aerogels for efficient solar desalination

Aerogel-like materials with three-dimensional pore structures show great potential in the field of efficient solar-driven interfacial evaporation by virtue of their fast water transport as well as efficient energy confinement properties. However, the preparation of aerogels is currently limited by high-cost strategies such as freeze drying or supercritical drying. Here, we present a foam template-assisted (FTA) strategy for atmospheric pressure drying of cellulose nanofiber (CNF) aerogels. Building a robust CNF network is the key to resisting surface tension during water evaporation and achieving drying in ambient environments, which is achieved through cleverly designed ionic cross-linking with the help of FTA. Cellulose aerogel (CA) constructed using the FTA strategy exhibit lightweight (9 mg cm−3) and porous properties (porosity: > 99 %). The tannic-coated CA (TCA) was achieved by further polymerizing tannic acid on the CA surface, which has excellent photothermal conversion capability. Meanwhile, TCA achieved an impressive evaporation rate of 3.58 kg m-2h−1 and an energy efficiency of 97.2 % at 1sun radiation by virtue of its excellent energy confinement and water management capabilities. This strategy provides a promising solution for the low-cost construction of aerogels as well as for the realization of efficient solar-driven interfacial evaporators.

3D morphometry of endothelial cells angiogenesis in an extracellular matrix composite hydrogel

Human umbilical vein endothelial cells (HUVECs) play a fundamental role in angiogenesis. Herein, we introduce digital holographic microscopy (DHM) for the 3D quantitative morphological analysis of HUVECs in extracellular matrix (ECM)-based biomaterials as an angiogenesis model. The combination of volumetric information from DHM and the physicochemical and cytobiocompatibility data provided by fluorescence microscopy and cytology offers a comprehensive understanding of the angiogenesis-related parameters of HUVECs within the ECM. DHM enables label-free, non-contact, and non-invasive 3D monitoring of living samples in real time, in a quantitative manner. In this study, the human amniotic membrane (HAM) is decellularized, pulverized, and combined with sodium alginate hydrogel to provide an in vitro substrate for modeling HUVEC angiogenesis. Our results demonstrate that modifying alginate hydrogel with HAM enhances its biofunctionality due to the presence of ECM components. Moreover, the DHM results reveal an increase in its porous properties, which, in turn, aids in interpreting the tubulation results.

Preparation, pore structure and properties of uniformly porous glass-ceramics sintered from granite powder using SiC@SiO2 foaming agent

Granite sludge produced during the processing of granite blocks should be efficiently recycled for environmental protection and as a sustainable resource. In this work, porous glass-ceramics were prepared by stepwise sintering of granite powder using core-shell SiC@SiO2 foaming agent. The SiC and SiC@SiO2 foaming agents were compared in terms of the sintering and foaming behaviors of the powder compacts by thermal expansion, thermogravimetry and mass spectroscopy. The foaming agent and foaming temperature were investigated to study their effects on the pore structure and properties of the porous glass-ceramics. The SiO2 shells of the SiC@SiO2 particles inhibited the oxidation of the SiC cores and the release of CO2 at the early stage of the sintering process, thus preventing pore coalescence and increasing the densification and specific strength of the sintered glass-ceramics. As the foaming temperature increased, the porous glass-ceramics exhibited a linear relationship between pore size and foaming temperature, and the specific strength first increased and then decreased due to pore coalescence and reduced crystallinity. Furthermore, the linear relationship between thermal conductivity and porosity indicates a closed pore structure, as demonstrated by computed tomography. At a foaming temperature of 1220 °C, the porous glass-ceramic has a porosity of 50.1 %, a specific strength of 16.6 kN⋅m/kg and a thermal conductivity of 0.747 W/(m⋅K). Numerical simulation confirms that lightweight glazed glass-ceramics have potential applications in energy-efficient building tiles.

U(Ⅵ) sorption by porous sodium zirconium phosphate pellets from aqueous solution

Zirconium phosphate is the first artificially produced layered phosphate that can sorb a variety of nuclides from solutions. Sodium zirconium phosphate (NZP) was a type of α-zirconium phosphate (α-ZrP). The porous sodium zirconium phosphate pellets (p-NZP-P) with a diameter of more than ∼3 mm were prepared and used for uranium sorption. The p-NZP-P could be immersed in solutions for more than 5 days without dissolving and structurally collapsing. The sorption properties of U(Ⅵ) on p-NZP-P in solutions were investigated by both static and dynamic sorption tests. Synthetic p-NZP-P was analyzed in detail using various characterizations to investigate their character and structural changes. In the static sorption experiment, the equilibrium sorption capacity reached the 77.5 ± 1.5 mg·g−1 when the initial concentration of U(Ⅵ) was 100 mg/L, pHinitial = 4.5, T = 25 ℃. Uranium sorption increased by ∼69 % and ∼215 %, respectively, when the initial uranium concentration was increased from 100 to 300 mg·L−1 and the temperature was increased from 15 to 55 °C. Furthermore, uranium sorption increased by ∼541 % when the initial pH increased from 2.5 to 4.5, while it decreased by ∼39 % when the initial pH increased from 4.5 to 7.0. The sorption data corresponded to the pseudo-second-order kinetic model and the Langmuir isotherm model, as well as the theoretically predicted value of sorption capacity (∼199.9 mg·g−1). The results of the dynamic sorption experiment showed that decreasing the quality, increasing the flow rate and the initial U(Ⅵ) concentration would shorten the breakthrough time. The dynamic sorption data agreed well with the Thomas model. The characterization confirmed the porous properties, while the U(Ⅵ) sorption mechanisms relate to –OH coordination and ion exchange. A radioactive rare earth wastewater treatment test suggested that p-NZP-P could be the potential uranium sorbent due to its good stability and efficiency. This paper opened opportunities for the development of practical materials for treating radioactive wastewater in the application of actual scenarios.

MOF-818 nanoparticles as radical scavengers to improve the aging resistance of silk fabric

Silk fabrics hold immense historical value as precious legacies left by our ancestors, yet they face significant damage during archaeological excavations, necessitating urgent protective measures. However, The current protective materials can’t effectively prevent the degradation of silk fabrics. Nanotechnology has emerged as a promising avenue for the consolidation and preservation of silk fabrics, offering novel concepts and materials. In this study, we propose an innovative and cost-effective method that uses the MOF-818 with a radical scavenging ability to enhance the protection of silk fabrics. The resulting demonstrates that the MOF-818 was the large surface area and porous properties, which exhibited excellent superoxide dismutase (SOD)-like activity at 10 ug/mL. The silk fabrics treated by MOF-818 displays small color difference, reduced the oxidation of functional group and prevents the degradation of silk fabrics. The successful development of this nanocomposite marks a significant advancement in silk protection, opening new horizons for the preservation of silk cultural relics.