Narrow Pore Size Distribution Research Articles

Evaluating Electronic Properties of Self‐Assembled Inner Hollow (InAs)12n (n = 1–16) Nanomaterials With High Solar Light‐to‐Electricity Efficiencies Using First Principle Modeling

ABSTRACTGeometries and electronic properties associated with growth patterns, energy gaps, and relative stabilities of (InAs)12n (n = 1–16) nanowires and nanosheets (nanoclusters) are systemically investigated at the GGA‐PBE level. The relative stabilities of (InAs)12n by means of the calculated fragmentation energies and cluster binding energies are determined and discussed. Particularly, the calculated energy gaps of (InAs)12n nanowires (2.261–2.271 eV) and nanosheets (2.228–2.412 eV) are distinctly localized at the regions of visible light energy ranges, indicating that large‐sized (InAs)12n nanosheets or nanowires are relatively wide‐band semiconductor nanomaterial; the calculated density of states reveals large‐sized porous (InAs)12n nanosheets and nanowires with a large surface area and narrow pore size distribution and slight thickness exhibit ultrahigh specific capacitance of trapping solar light energies and high light‐to‐electricity conversion efficiencies in solar energy absorption or conversion or photovoltaics. Consequently, (InAs)12n‐based nanomaterials are favorable for optoelectronic and energy miniaturized devices. Interestingly, the variable sizes depended energy gaps of (InAs)12n nanosheets manifest quantum size effect. Especially, the gradually increased charge‐transfers in large size (InAs)12n nanowires and nanosheets with their sizes can significantly lead to the ionic bonding and metallic characteristic, which can stabilize themselves. Comparison with experiment results available is made.

Multifunctional role of surfactant in fabricating polyamide nanofiltration membranes for Li+/Mg2+ separation

Extracting Lithium from salt-lake brines can effectively alleviate global lithium scarcity. Separating the co-existing Mg2+ ions from Li+ ions in the brines is essential. While thin-film composite (TFC) nanofiltration (NF) membrane show potential for this separation, commercial NF membranes with negatively charged surfaces fail to meet the high rejection requirement for Mg2+ ions due to the electrostatic attractions between membranes and cations. Positively charged NF membranes fabricated by interfacial polymerization (IP) between aqueous phase polyethylenimine (PEI) and hexane phase trimesoyl chloride (TMC) have shown promise for Li+/Mg2+ separation. However, lithium extraction efficiency is greatly limited by the relatively low permeance and high lithium rejection of the membrane caused by an excessively cross-linked structure. Therefore, optimizing the pore size while maintaining the positive charge of PEI/TMC-based TFC membranes is necessary. We propose adding anionic surfactants to the aqueous PEI solution to modulate PEI/TMC-based NF membrane formation. Surfactants control PEI diffusion in IP through their interactions and improve reaction uniformity at the water-hexane interface. This results in a narrow pore size distribution of the PA network. In this study, three sulfate surfactants with varying alkyl chain lengths were used to control membrane formation. Results showed that sodium n-decyl sulfate (SDES), the shortest sulfate surfactant, improved membrane performance most effectively. The optimized membrane exhibited a crumpled surface and relatively loose pore structure with narrow pore size distribution. It demonstrated a pure water permanence of 5.65 L m−2 h−1 bar−1, high MgCl2 rejection of 92.6 %, and low LiCl rejection of 21.5 %. After filtering a Mg2+ and Li+ binary mixture solution, the Mg2+/Li+ ratio decreased significantly from 40 (feed) to 3.08 (permeate). This study provides an efficient strategy for preparing PEI/TMC-based NF membranes with favorable Li+/Mg2+ separation performance.

Synthesis of chiral mesoporous silica nanoparticles for the adsorptive removal of the chiral insecticide sulfoxaflor from water.

Mesoporous materials have garnered significant interest because of their porous structure, large surface area and ease of surface functionalization to incorporate the functional groups of choice. Herein, chiral mesoporous silica nanoparticles (CMSNPs) were prepared using quaternary amino silane as the template, tetramethyl orthosilicate as the silica source and proline and cellulose as chiral selector. The developed CMSNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis, BET surface area analysis and BJH pore size/volume analysis. It was observed that the CMSNPs have high specific surface area and narrow particle size and pore size distribution. These CMSNPs were used as adsorbents for separation of the chiral insecticide sulfoxaflor. The effects of various parameters that affect adsorption, such as initial concentration of the analyte, adsorbent dose, time and pH, were evaluated, and the optimum values were determined. At optimum conditions, the removal efficiency and adsorption capacity were 98.5% and 435.45 mg g-1, respectively. Further, adsorption isothermal study was carried out using Freundlich and Langmuir models. Results showed that mesoporous silica nanoparticles functionalized with amide-bonded cellulose are promising and cost-effective adsorbents for the removal of chiral pesticides from water and wastewater.

Ultrathin Graphene Oxide Nanoribbon Networks as Architects of Enhanced Performance in Polyamide‐Based Nanofiltration Membranes

AbstractCustomized architecture and chemistry play a pivotal role in conferring exceptional permeability and selectivity to polyamide (PA) membranes for desalination and ionic separation. Herein, a new interfacial polymerization (IP) template, the ultrathin graphene oxide nanoribbon (GONR) networks, is developed to meet the need for minimizing the funnel effect and mediating the IP reaction toward a highly permeable and selective membrane. The coated GONR template efficiently represents the gutter layer role and regulates the adsorption and transport of amine monomers at the GONR interface, which is studied by molecular simulation as well. The structure, electrostatic interaction, capillary rise, and nanoconfinement of the IP template are manipulated by different GONR loadings to optimize the membrane structure. The optimized GONR loading at 0.02 g m−2 results in a hybrid layered GONR/PA‐thin‐film‐composite nanofiltration membrane with nanostrip crumpled structure beyond the PA context, ultrathin 15 nm PA nanofilm, 80% cross‐linking degree, and narrow pore size distribution. The membrane passes the upper bound trade‐off with a permeance of 21.3 L m−2 h−1 bar−1 and a remarkable rejection of 98% for Na2SO4. This research offers a fresh perspective on comprehensively understanding the role of the IP template in creating a desired membrane for efficient desalination and ionic separation.

Better Together: Synergic Effect of Gallium‐Based Catalyst and Porous Support for Reduction Reactions

AbstractLiquid metal solutions are a new class of catalysts with outstanding properties in terms of catalytic conversion and resistance to coking. Finding the perfect combination of catalytic particles with homogeneous size distribution and support material able to stabilize them during catalysis is key for preparing model systems to gain understanding of these complex catalytic processes. In this work, we present a method for the preparation of small and narrowly distributed gallium–palladium particles supported on inverse opals, interconnected 3‐D porous networks with a very narrow pore size distribution. Our platform is a promising candidate as supported liquid metal catalytic system thanks to its permeability to fluids and its confined pore environment, which prevents the coalescence of the metal alloy, thus maximizing the surface area available for the catalytic reaction. We demonstrate their enhanced performance when compared to other state of the art systems giving a proof of concept of their application as catalysts for a simple model reaction, the reduction of methylene blue.

Macromolecular Architecture in the Synthesis of Micro- and Mesoporous Polymers.

Polymers with micro- and mesoporous structure are promising as materials for gas storage and separation, encapsulating agents for controlled drug release, carriers for catalysts and sensors, precursors of nanostructured carbon materials, carriers for biomolecular immobilization and cellular scaffolds, as materials with a low dielectric constant, filtering/separating membranes, proton exchange membranes, templates for replicating structures, and as electrode materials for energy storage. Sol-gel technologies, track etching, and template synthesis are used for their production, including in micelles of surfactants and microemulsions and sublimation drying. The listed methods make it possible to obtain pores with variable shapes and sizes of 5-50 nm and achieve a narrow pore size distribution. However, all these methods are technologically multi-stage and require the use of consumables. This paper presents a review of the use of macromolecular architecture in the synthesis of micro- and mesoporous polymers with extremely high surface area and hierarchical porous polymers. The synthesis of porous polymer frameworks with individual functional capabilities, the required chemical structure, and pore surface sizes is based on the unique possibilities of developing the architecture of the polymer matrix.

Adsorption and oxidation of β-carotene by montmorillonite bleaching clays

The role that clay mineral acidity, specific surface area (SSA) and pore size distribution (PSD) have on the adsorption and oxidation of β-carotene by montmorillonite bleaching clays was investigated. Five commercially available clay minerals were studied, including three acid-activated montmorillonites (AACs) (K10, K30 and 22B), one aluminium-pillared montmorillonite (Al-PC) and an untreated montmorillonite (SWy-3). Each underwent physicochemical characterisation. X-ray diffraction and N2 gas sorption techniques provided structural and textural information. Titration with n-butylamine in the presence of Hammett and arylmethanol indicators characterised the concentration and strength of clay acid sites. The kinetics of β-carotene adsorption were then measured as a means of comparing their adsorptive power. The tendency of each clay to oxidise β-carotene to a variety of carotenoid-oxidation-products (COPs) was examined by analysing extracts of each clay with ultra-high-performance liquid-chromatography mass-spectrometry (UPLC-MS). The AACs adsorption and oxidation of β-carotene exceeded that of SWy-3 and Al-PC. This was attributed to a greater number of stronger acid sites, and a higher SSA. The clay PSD was also shown to play a significant role. 22B, which had a narrower PSD than K10 or K30, showed a lower tendency to adsorb β-carotene despite having the greatest number of strong acid sites. Lastly, the AACs had a greater oxidative power than SWy-3 or Al-PC and produced COPs in greater abundance than the other clays. They also produced more COPs of a higher oxidation state relative to β-carotene. These findings provide helpful information for the selection of efficient adsorbents for use in vegetable oil bleaching.

Preparation of ceramic membranes with small pore size, narrow pore size distribution and investigation of oil-water separation mechanism

To solve the problems of wide pore size distribution, complex preparation process, poor performance and low anti-fouling performance of commercial ceramic membrane prepared by sintering technology. In this study, the ceramic membrane (ACM-W) with small pore size (83 nm), narrow pore size distribution and high anti-fouling ability was prepared by coating the water glass (WG) + Al2O3 slurry on commercial Al2O3 ceramic membrane (ACM-0) by one-step. WG was used as an inorganic binder for bonding and pore plugging. The chemical structure of the membrane surface was characterized and analyzed. The bonding mode between WG and Al2O3, and the effect of WG on the surface microstructure of the membranes were investigated. The surface microstructure, pore size distribution and anti-fouling ability of membranes were revealed. The findings showed that the pore size of 83 nm accounted for 98.3 % of the ACM-W pore size distribution. The rejection for emulsified oil of 99.96 % and the flux recovery rate (FRR) of 98.7 % achieved for ACM-W, which indicated that ACM-W has excellent separation performance and anti-fouling ability. Based on the above results, combined with the size change of oil droplets before and after separation, wettability, surface charge and the cleaning process of the ACM-W, the anti-oil fouling mechanism of “charge repulsion & pore barrier” for the membrane was presented. This study introduces a novel idea for preparation of the ceramic membrane with high filtration accuracy and anti-fouling ability, and a fresh insight into the anti-fouling mechanism of ceramic membranes.

RICE HUSK – AGRICULTURE WASTE AS RAW MATERIAL FOR SBA-15 MESOPOROUS SILICA

The obtaining of molecular sieves using alternative sources of silica represents a promising approach for replacing the conventional expensive silica sources, such as tetraethyl orthosilicate. These new raw materials with low costs can be agriculture wastes, such as barley husks, rice husks, wheat straws, or wheat husks. Therefore, the synthesis of silica nanomaterials using rice husk ash has been the focus of various studies, considering also the ecological, economic, and environmental issues. SBA-15 is a mesoporous silica sieve having uniform hexagonal pores with narrow pore size distribution and tuneable pore diameter, between 5 and 15 nm. Typical SBA-15 presents high surface area, increased thermal and mechanical stability, and is not harmful to the environment. Consequently, it represents well-suited material for different applications, such as adsorption and separation, support material for catalysts, or template to produce ordered mesoporous carbon. Considering all the above-mentioned details, this study reports the preparation of SBA-15 type mesoporous silica using rice husk ash as silica source, followed by a hydrothermal method. The morpho-structural properties of mesoporous silica were elucidated using various techniques, proving that the resulted mesoporous silica had typical features of SBA-15 molecular sieve, but with lower specific area (around 140 m2/g) and pore volume (0.240 cm3/g) than the one obtained from commercial sources.

Versatile organosilicone porous materials for the detection of nitroaromatics and the visualization of fingerprints

Achieving explosive detection and fingerprints visualization at the same time is of great significance. Towards this end, based on the cage structure and multiple reaction sites of octavinyl polyhedral oligomeric silsesquioxane (OVS), a series of multifunctional silicone porous materials OVSBs and OVSTs were designed and synthesized with 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-triazine. These porous materials have narrow pore size distribution, high specific surface area and pony-sized that smaller than 5 nm. The micropore volume ratio of porous materials can be changed by regulating the molar ratio of OVS to functional compounds. OVSB-2 shows excellent adsorption capacity for fluorescent dyes due to its highest specific surface area and high micropore volume ratio. OVSB-2 also has superior fluorescence characteristic, which can quickly detect nitroaromatic compounds within 20 s. This work provided a new method for expanding the application of silicone mesoporous materials in explosive detection and fingerprints visualization simultaneously.

Evaluating Electronic Properties of Self‐Assembled Indium Phosphide Nanomaterials as High‐Efficient Solar Cell

ABSTRACTGeometries and electronic properties associated with relative stabilities and energy gaps of porous (InP)12n (n = 1–12) nanoclusters (NCs) (nanowires and nanosheets) are systemically studied by density functional method. The relative stabilities of (InP)12n NCs through the calculated fragmentation energies and cluster‐binding energies are determined and discussed. Interestingly, the calculated energy gaps of (InP)12n nanowires and nanosheets are localized at regions of visible light energy ranges. (InP)12n are relatively wide‐band semiconductor solar energy nanomaterial. The calculated density of states reveals large‐sized porous (InP)12n nanosheets and nanowires with narrow pore size distribution and slight thickness and a large surface area manifest ultrahigh specific capacitance of trapping solar light energies and high light‐to‐electricity conversion efficiencies in solar energy absorption or conversion or photovoltaicsm. Particularly, (InP)12n NCs maintain their elemental properties of individual (InP)12 clusters in the energy gaps of (InP)12n (n > 4). NCs are almost independent of variable sizes. Specifically, the size‐dependent charge transfers of In atoms in (InP)12n NCs exhibit that ionic and covalent bonding exist in (InP)12n NCs and can stabilize (InP)12n NCs. Comparison with experiment results available is made.

Fabrication of model ultrafiltration membranes with uniform, high aspect ratio pores

In this manuscript, we report the facile fabrication of large-area model membranes with highly uniform and high aspect ratio pores with diameters <20 nm. These membranes are useful for fundamental investigations of separation by size exclusion in the ultrafiltration regime, where species to be separated from solution have dimensions of 1–100 nm. Such investigations require membranes with narrow pores and high aspect ratios such that the Hagen–Poiseuille equation is followed, enabling well-known models such as the hindered transport model to be evaluated and other affecting factors to be ignored. We demonstrate that the sub-20 nm pores in the membrane are of sufficiently high aspect ratio such that water flux through the membrane is consistent with the Hagen–Poiseuille equation. The fabrication relies on self-assembling block copolymers to form uniform, densely packed patterns with sub-20 nm resolution, sequential infiltration synthesis to convert the block copolymer in situ into a mask with adequate contrast to etch pores with an aspect ratio >5, and low-resolution photolithography to transfer the pattern over a large area into a silicon nitride membrane. Model membranes with narrow pore-size distribution fabricated in this way provide the means to investigate parameters that impact size-selective ultrafiltration separations such as the relationships between solute or particle size and pore size, their distributions, and rejection profiles, and, therefore, test the validity or limits of separation models.

Effect of Pore Structure on Tertiary Low-Salinity Waterflooding in Carbonates: An In-Situ Experimental Investigation

Summary Low-salinity waterflooding (LSW) is an environmentally friendly and economically feasible technology that enhances oil recovery by controlling ionic composition or brine salinity. The recovery efficiency of this technique is strongly affected by the rock pore structure that governs the flow behavior of the injected brine. However, existing experimental studies elaborating on the relationship between pore structure and LSW performance in carbonates remain scarce. To address this gap, three carbonate plugs with different pore structures were displaced sequentially with synthetic high- and low-salinity brine under the capillary-dominated flow regime. High-resolution micro-computed tomography (CT) was used to obtain 3D images of different displacement stages, visualizing the fluid distribution. After image processing and contact angle calculation, it was found that the primary mechanism for enhanced recovery was wettability alteration, transitioning from oil-wet to weakly oil-wet. Significant differences were observed among the three samples. Sample 1 showed the highest additional recovery (22.2%), followed by Sample 2 (11.2%), and the lowest was Sample 3 (4.5%). Despite Sample 1 and Sample 3 having similar and narrow pore size distributions, they exhibited different fluid behaviors during LSW: In Sample 1, oil was mainly displaced from medium-sized pores, whereas in Sample 3, small pores were the main target for brine. The large coordination number likely enhanced the relative permeability of the high-salinity brine. The low-salinity brine followed the pathway formed by the high-salinity brine, affecting the LSW performance. This work provides novel insights into how pore structure affects oil recovery by comparing the response of multiple carbonate samples to LSW.

Waste cigarette filters-based polymer blends membrane for filtration of high loaded natural organic matter river water

Waste cigarette filter (WCF) is one of the most common wastes found in the environment. Cigarette filters contain up to 96% cellulose acetate (CA), which can be used as a material for membrane fabrication. However, the CA-based membrane from WCF posed a weak mechanical property (brittle). Therefore, the objective of this work is to improve mechanical property of CA-based membrane from WCF by preparing blend membranes with polyvinylidene fluoride (PVDF) polymer and evaluate their performance for filtration of real river water containing high natural organic matter (NOM) concentrations. The variations of WCF and PVDF used were 100:0, 75:25, 50:50, 25:75, and 0:100. The membranes were then characterized to determine the morphology, pore size and pore size distribution, hydrophilicity, mechanical properties, and filtration performance of the membrane using clean water and river water. The SEM test results showed the presence of spherulites on the surface of the blend membrane, indicating that crystallization occurred during membrane formation. The spherulites resulted in smaller pore size, narrower pore size distribution, higher hydrophilicity, and mechanical properties. Meanwhile, the filtration test results showed that blend membranes produced higher permeability compared to pristine WCF, PVDF, and commercial-based CA membranes, where the result of river water permeability was in the range of 875–1062.5 L/m2.h.bar. The membrane fouling formation was aligned well with the result of permeability and is dominated by irreversible fouling formation from the dynamic cake layer built on the membrane surface, with NOM rejections of 26.6–33.8%, suggesting the need for further developments.

Pore-scale study of coupled heat and mass transfer during primary freeze-drying using an irregular pore network model

This study presents a pore network (PN) model with transient heat transfer and quasi-steady transitional vapor transport that is for the first time applied to irregular porous structures that are obtained by reconstruction of X-ray tomography image data. In contrast to previous studies, the irregular pores are not approximated by spheres but implemented in their original shape. Secondly, instead of assuming cylindrical throats as pore connections, the actual distance between pore centers as well as the pore cross sections are used for the computation of the vapor transport coefficient. The control volume elements of the computational model are matched with the cells obtained by Voronoi tessellation. The improvements have clear advantages over former approaches where the reconstructed void space is usually strongly simplified by balls and sticks confined in a regular lattice structure. A freeze-dried sample of maltodextrin DE12 with 20% (w/w) solid content is used for benchmarking the new methodology. Its morphological and thermal properties are determined by the novel PN model. The simulation results of primary freeze-drying (FD) are compared to reference cases in two ways. First, the differences in heat and mass transfer kinetics as compared to regular PNs are emphasized. Secondly, the PN simulation results are confronted with a simple literature model that neglects pore size distribution (PSD) and transient heat transfer. It is shown that already in small domains with relatively narrow PSD, the variation of the mass transfer coefficient affects the computed sublimation fluxes and yields a significant deviation from the simpler literature model. Moreover, it is revealed in this study that the structure has a significant impact on the sublimation front temperature. This is demonstrated by the comparison of FD in the irregular PN to a regular PN with almost identical PSD but different porosity. The development, verification, and benchmarking of the new PN model can be seen as an important step for studies of the structure dependence of FD.

Magnesium nitrate-tricine nanoparticles: Temperature impact to enhancing third order optical nonlinearity

Nano-hybrid promoted as materials with improved optical properties. The aim of this study was to analyze differences in optical properties at micro-scale. This research focuses on the impact of reaction temperature during the creation of magnesium nitrate-tricine nanoparticles through chemical vapor deposition. The study investigates how temperatures of 200°C and 300°C affect the particle size, crystallinity, and morphology of the nanoparticles. Optimizing these properties is essential for achieving the desired third-order NLO effect. By understanding the influence of temperature on nanoparticle characteristics, researchers can develop more effective NLO materials for future photonic devices. This study explores the chemical and structural differences between MNT 300 and MNT 400 materials using various techniques. Spectroscopic analysis reveals similarities in both materials with a shared peak at 1400 cm−1. However, MNT 400 exhibits additional peaks suggesting the presence of aromatic rings, nitro compounds, or variations in N–H bonds. Both MNT 300 and MNT 400 exhibit micro porous behaviour with a narrow pore size distribution around 14 nm to 15 nm, indicating tightly packed structures. Transmission Electron Microscopy analysis shows a wide particle size range (2 nm to 200 nm) in both materials, suggesting the presence of atomic clusters, individual molecules, and potentially agglomerated structures. FT-Raman spectroscopy reveals higher intensity peaks in MNT 400, which could be due to a higher concentration of specific bonds, a more ordered structure, or enhanced Raman scattering. This suggests greater crystallinity or molecular uniformity in MNT 400 compared to MNT 300.

An Engineering Porous Spherical Carbon Cathode for High-Energy Sodium-Ion Capacitor.

Sodium-ion hybrid capacitors (SICs) are emerging as promising devices that can balance energy and power output. However, the lack of a high-capacity cathode that can match the anode has limited its further application. In this work, we develop an efficient method to prepare spherical porous carbons (SPCs) with great specific surface area and narrow pore size distribution from coal-based humic acid via spray drying and a subsequent chemical activation process. Thanks to this unique porous structure, the SPC cathode has a superb capacity of 223 F g-1 at 0.05 A g-1, as well as splendid rate performance and cycling stability. SICs constructed by an SPC cathode and hard carbon anode can exhibit a high energy density of 179.8 Wh kg-1 at 155 W kg-1 and achieved 89.4% capacity retention after 10 000 cycles at 0.5 A g-1. This outcome presents a viable approach to attaining high-capacity cathodes for constructing outstanding performance hybrid capacitors.

Porous organic cage induced high CO2/CH4 separation efficiency of carbon molecular sieve membranes

Porous fillers have been incorporated into precursor membranes to fabricate carbon molecular sieve (CMS) membranes, where the interfacial compatibility between fillers and matrix significantly influences the separation performance of converted CMS membranes. To address this issue, we introduce molecular fillers of porous organic cages (POCs) into precursor membranes, the organic composition and discrete molecular characteristics of which can enhance the compatibility with the polymer matrix (PIM-1), bringing enhanced porosity and narrowed pore size distribution, especially in the ultra-micropore region, to the CMS membranes. The obtained CMS membrane shows simultaneously improved gas permeability and selectivity wherein the optimized CMS membrane pyrolyzed at 600 °C with 10 wt% POCs loading (CMS-10%-600) exhibits a CO2 permeability of 2002 Barrer and a CO2/CH4 selectivity of 221.6, surpassing the 2019 CO2/CH4 upper bound and superior to most of reported CMS membranes. Due to the incorporation of POC, the CMS-10%-600 membrane demonstrates a 147.5 % increase in CO2 permeability and a 297.1 % increase in CO2/CH4 selectivity compared to pristine PIM-1-based CMS membrane, along with the excellent aging resistance for over 30 days. This study provides new insights into the design of high-performance CMS membranes for gas separation.

Ultrasound-assisted freezing for the preparation of aerogel-based intelligent packaging

Due to their highly porous and high specific surface area, aerogels are promising materials for intelligent food packaging. However, aerogel-based intelligent packaging prepared by traditional freeze-drying methods severely limits the preparation efficiency and the packaging performance of the aerogels due to the low freezing efficiency and the large and uncontrollable pore size caused by the uncontrolled growth of the crystals during freezing; this leads to the destruction of the aerogel structure. In this study, an aerogel-based food intelligent packaging was prepared using gelatin and gum Arabic (GG) as the substrate materials for real-time shrimp freshness detection. An ultrasound-assisted freeze-drying (UAFD) strategy was applied to improve the freezing efficiency of the cavitation-induced nucleation of aerogel. By affecting secondary nucleation, the UAFD-160 W strategy produced aerogels (GG-160) with smaller pore sizes (14.76 μm) and narrower pore size distributions than those using intelligent packaging prepared by the traditional freeze-drying method (GG-0, pore size = 254.14 μm). Due to the advantages of the above structure, the GG-160 aerogel has a significantly improved hardness (28956.5 ± 101.6 N), excellent water resistance and hydrophobicity (93.6 ± 0.99°), sensitive ammonia responsiveness, and stable properties under high humidity. Consequently, compared with that in the GG-0 treatment, the color of the shrimp in the GG-160 treatment was more sensitive to spoilage. The proposed UAFD strategy provides a new way to improve the properties of aerogels by structural modulation such that the prepared aerogels have better food packaging applications.

A novel 3D hierarchical NiFe-LDH/graphitic porous carbon composite as multifunctional adsorbent for efficient removal of cationic/anionic dyes and heavy metal ions

Developing effective adsorbents for wastewater purification is crucial, as excessive emissions of toxic dyes and heavy metal ions have been proven harmful to ecosystems and human health. A NiFe-layered double hydroxide/graphitic porous carbon (NiFe-LDH/GPC) composite was fabricated by introducing NiFe-LDH nanosheets into GPC via a simple hydrothermal method to utilize the advantages of both materials fully, and thus ultimately obtain a composite adsorbent with improved adsorption properties. The samples obtained were comprehensively characterized by various characterization means, and the effects of several critical influential factors on the pollutant uptake capability of the NiFe-LDH/GPC were also studied through batch experiments. The results show that the as-synthesized NiFe-LDH/GPC exhibits a three-dimensional (3D) fluffy ultrathin-wall hierarchical porous structure, which possesses a high specific surface area and pore volume separately up to 506.74 m2/g and 0.22 cm3 g−1 as well as a relatively narrow pore size distribution. These characteristics bring advantages to enhance the adsorption ability of the NiFe-LDH/GPC for cationic/anionic dyes and heavy metal ions such as congo red (CR), malachite green (MG) and hexavalent chrome (Cr(VI), which reached the maximum adsorption capacity of 1726.51 mg/g, 1157.11 mg/g and 155.72 mg/g under the optimum conditions, respectively. Meanwhile, the adsorption behavior can be well described by the pseudo-second-order kinetic model and Langmuir isotherm model, reflecting that the sorption process mainly occurred chemically in the adsorbent monolayer. Furthermore, the NiFe-LDH/GPC maintained relatively high adsorption performance after multicycle testing, manifesting its good recyclability and stability.