Surface Pore Research Articles

Flexible polyaniline/carbon quantum dots films for enhanced electrochromic performance

Polyaniline (PANI) conducting polymers exhibit potential electrochromic properties. However, the electrochromic response of PANI films in the infrared (IR) ranges is restricted by their dense structure. Herein, the polyaniline/carbon quantum dots (PANI/CQDs) films were synthesized with sulfuric acid (SA) and CQDs as the dopants. The tetrahedral structures of SA contribute to the formation of highly oriented lamellar PANI. The synergistic effect between CQDs and PANI promotes the loose and porous surface morphology, thereby improving the electrochromic performance of PANI film. The PANI/CQDs porous film for the polymerization charge of 0.5C (PANI/CQDs-5) shows the optimal electrochromic properties and IR modulation capacity, achieving an optical contrast (ΔT) values of 53 % at 850 nm, and with the emittance variation (Δε) values of 0.41, 0.46 and 0.42 in 3–5 μm, 8–14 μm, and 2.5–25 μm, respectively. Furthermore, the switching time of the PANI/CQDs-5 films for coloration and blanching are 2.5 s and 3.6 s, respectively, with over 95 % retention after 100 cycles. Theoretical calculations verified that PANI/CQDs composite films displayed outstanding electron and ion transfer kinetics, facilitating superior electrochromic properties.

Purification, structural identification, in vitro hypoglycemic activity and digestion characteristics of polysaccharides from the flesh and peel of wampee (Clausena lansium)

In this study, two polysaccharides were isolated from the flesh and peel of wampee, termed as PWP-F and PWP-P respectively, and their structural characteristics, in vitro antioxidant and hypoglycemic activities and digestion were investigated. Results indicated the molecular weight of PWP-F was higher than that of PWP-P and they were both mainly composed of galactose and arabinose. Both polysaccharides exhibited α-type and β-type glycosidic linkages based on FTIR analysis. NMR spectroscopy revealed that PWP-F mainly consisted of α-Araf-(1→, →3,5)-α-Araf-(1→, →2,5)-α-Araf-(1→, →4) → β-Galp-(1 → and α-GalpA-(1→, while PWP-P was composed of α-Araf-(1→, →3)-α-Araf-(1→, →5)-α-Araf-(1→, →3,6) → β-Galp-(1→ and α-GalpA-(1→. Scanning electron microscopy showed that PWP-P had more porous surface structure compared to PWP-F. Moreover, PWP-P exhibited superior antioxidant activity and significant inhibition of both α-glucosidase and α-amylase compared to PWP-F. Specifically, PWP-P demonstrated mixed inhibition against α-glucosidase and α-amylase. In vitro digestion results showed the molecular weight, polysaccharide and reducing sugar content of PWP-F and PWP-P decreased after simulative gastrointestinal digestion. Overall, PWP-P has great potential as a kind of new antioxidant and hypoglycemic agent.

Optimization of process parameters for preparing AlN nanopowders by combining carbon-containing droplet combustion and carbothermal reduction methods

In this research, AlN nano-powders were prepared by combining carbon-containing droplet combustion (CCDC) and carbothermal reduction (CR) methods. Firstly, Al2O3+C mixed precursor was synthesized by the CCDC method, and then AlN nano-powder was obtained by the carbothermal reduction of this CCDC precursor. The effects of urea and glucose contents, ignition temperature, and combustion atmosphere on precursors and AlN powders were studied in detail. The results showed that with the molar ratio of urea to aluminum nitrate (U/A) of 3, the atomic ratio of carbon to aluminum (C/Al) of 6, and the ignition temperature at 800 °C under air atmosphere, the prepared precursor was composed of hollow and spherical structure particles exhibiting rough and porous surface morphology with high specific surface area (SSA) (41.4 m2/g). AlN nano-powders obtained by the carbothermal reduction of this precursor were found to be consisted of fine particles with the size of 20–30 nm with high SSA of 39.9 m2/g.

Preliminary results in the manufacture of anodic electrodes for potential use in microbial fuel cells.

Abstract Microbial fuel cells are a bioelectrochemical technology that uses different types of waste as fuel sources to generate sustainable and environmentally friendly electricity. Various MFCs have been developed, with the electrode used being a crucial problem due to its high manufacturing cost. This research shows that electrodes can be manufactured quickly and economically using activated carbon (100 g), sugar (80 g), ethanol (250 ml), and pine resin (200 g). For its demonstration, grape waste was used in a single-chamber MFC for 35 days. The manufactured electrode generated a Rint. of 18.471 ± 2.475 Ω, whose current density was 8.348 ±0.768 mW/cm2 at a current density of 5.166 A/cm2. The electrical potential shown was 0.889 ± 0.017 V and 4.571 ± 0.061 mA, with an ORPmax of 81.495 ± 1.874 mV, operating at a pH of 7.26 ±0.19. The micrographs made by scanning electron microscopy showed porous surfaces with carbonaceous substances in the final monitoring stage. These preliminary results showed excellent performance of the electrodes, showing their potential for use in MFCs in an economical way.

Surface morphology-controlled poly(ε-caprolactone) nanofiber anti-fouling coating: A promising approach for marine applications

Abstract To effectively combat marine biofouling, biomimetic anti-fouling coatings have garnered widespread attention as a novel anti-fouling method. Based on this biomimetic concept, this study adjusted the electrospinning process parameters and selected different solvent systems to effectively modify the surface morphology of poly (ॉ-caprolactone) (PCL) nanofiber coatings, developing a non-toxic anti-fouling smooth surface. These biodegradable slippery liquid-infused porous surfaces (SLIPS) coatings offer a simple way to prepare maritime anti-fouling coatings in an eco-friendly manner. They can withstand a variety of liquid, material, and microbiological contaminations.

Influence of in-situ lunar temperature on the pore structure and solid phases of alkali-activated lunar regolith simulant

The construction of extraterrestrial bases has become an indispensable step in the active exploration of deep space. In this study, alkali-activated lunar regolith simulant (AALRS) activated by sodium hydroxide (SH) and sodium silicate (SS) were prepared and then cured at various lunar temperatures. The compressive strength was tested, and the pore structure characteristics were characterized using mercury intrusion porosimetry (MIP), followed by further in-depth quantitative analysis through fractal theory. The solid phases were characterized using thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). It is found that all the fractal curves are divided into three regions, and the fractal dimensions in all regions are between 2 and 3, suggesting the pores of AALRS paste always have self-similar physical significance. The fractal dimension D1 of the small pore is the largest, followed by fractal dimension D3 of the great pore and fractal dimension D2 of the middle pore. The increase in modulus and temperature leads to an increase in the pore surface area, fractal dimension, amount of N-A-S-H gel and compressive strength and a decrease in total pore volume and characteristic pore diameter, which is mainly attributed to the nucleation effect of soluble Si. The turning pore diameter at the micrometer scale and excessive porosity of AALRS paste, which is distinctly different from that of common cementitious materials, demonstrates looser pore structure of AALRS paste. Based on these results, the influence mechanism of in-situ lunar temperature on the performance of AALRS paste is profoundly discussed and elucidated, which provides a deep understanding of designing and tailoring the various properties of AALRS material.

Investigation on the evolution of concrete pore structure under freeze-thaw and fatigue loads

Hydraulic concrete structures in seasonal frozen regions serve under freeze-thaw cycles and cyclic loading conditions which cause notable alterations in the concrete pore structure and a significant reduction in the mechanical properties and durability of concrete. To understand the macroscopic and mesoscopic damage processes and mechanism of concrete subjected to freeze-thaw cycles and cyclic loading lead, the compressive experiment and computed tomography test of concrete after freeze-thaw and fatigue loading tests were conducted. And the influences of freeze-thaw cycle damage and cyclic loading damage on the pore structure of concrete were analyzed. The relationships between concrete pore fractal dimension, compressive strength, and elastic modulus were revealed. The concrete average pore size can be regarded to grows linearly under freeze-thaw and cyclic loading. The porosity, pore volume, and pore surface area increase with the increase in freeze-thaw cycles, and their relationship can be represented by a quadratic function. However, they first decrease and then increase with the increase of loading cycles after a specific freeze-thaw cycles number. Under the combined action of freeze-thaw cycles and cyclic loading, the non-uniformity degree of concrete pore distribution decreases, and the overall structure is more regular. The distribution of single pore morphology tends to be spherical and banded, respectively. The cyclic loading promotes the extension of the internal pores and cracks of freeze-thaw-damaged concrete which aggravates damage of concrete. Under freeze-thaw cyclic loading, the concrete compressive strength and elasticity modulus is linearly and positively correlated with fractal dimension. With the increase of loading cycles number after freezing and thawing, the fractal dimension and compressive strength decrease, and the elasticity modulus has a larger dispersion. The relationship model between concrete compressive strength and fractal dimension can well describe the macroscopic and mesoscopic evolution of concrete under freeze-thaw and cyclic loading. The results can provide a scientific basis for improving the design and maintenance of concrete and benefit extending the long-term service life of hydraulic concrete structures in cold climates.

Modification of activated carbon through chemical-physical activation method with KOH and 60Co gamma irradiation from banana leaf waste

Abstract Until now waste is still a problem in many big cities in Indonesia. In addition, the amount of waste increases as the population increases. Banana leaf waste is no exception, which is included in other types of waste, which accounts for 6.33% of the total waste in Indonesia in 2022. Utilization of banana leaf waste as a raw material for activated carbon production can also be an alternative to reducing the amount of wasted banana leaf waste because they contain various kinds of organic compounds. Activated carbon is widely used as an adsorbent in various sectors, especially in the industrial sector. Production of activated carbon must go through an activation process to enlarge the surface pores either chemically or physically, or even both. This study aims to compare the results of activated carbon surface area and functional groups using the chemical-physical activation method from banana leaf biomass raw materials with KOH and gamma irradiation at various doses. The research method used is an experimental method consisting of 4 stages: dehydration, carbonization, activation, and characterization. The research was started by dehydrating the leaves and continued with the carbonization stage at 350°C for 30 minutes. Carbon was divided into four samples that consisted of 1 blank and 3 test materials that activated with 30% (w/v) KOH solution for 24 hours and gamma-irradiated with a dose of 10, 30, and 50 kGy. Results were characterized using FTIR and BET. The effect of gamma 60Co irradiation on the activated carbon material from banana leaf waste can increase the peak transmittance value of the activated carbon functional group due to the formation and reaction of free radicals on its surface. Increase in the surface area (from 6.504 to 24.04 m2/g) is also associated with an increase in the absorbed dose due to the formation of more free radicals. However, the surface area obtained is not as expected due to the possibility of pore blockage and excessive activation time, which causes the surface area of the material to be small.

Scale-span feature of surface analysis, macromolecular and pore structure in coal: Implications for inherent evolutionary mechanism of morphological microstructure

Morphological microstructural evolution of tectonic coal determines CBM storage and transportation mechanism as well as the occurrence of coal and gas outburst. Scale-span morphological feature of original and tectonic coals was characterized by AFM, Raman spectrum and physisorption method. The results demonstrate that metamorphism could remold the surface property of coal from rugged band to flat porous structure with pore form factor from 0.572 to 0.831, promoting the formation of regular and round pores. Tectonism facilitates ability of gas sorption in coal, breaking the basic structural integrity. Metamorphism could facilitate the ordered macromolecular structural evolution on recombination and aromatization as well as condensation; besides, tectonism may promote the evolution and development of microcrystalline structure in advance. The aforementioned results have revealed essential differences in morphological microstructure between original and tectonic coals, which are of great guiding significance to safe mining of CBM and prediction of coal and gas outburst.

Investigation of the Effects of Waste Olive Pomace on Vermicompost

The effects of olive pomace on the degradation of organic matter were investigated via vermicomposting. Biomass consisting of eggshell, cabbage, banana peel, napkin, nutshell, cattle manure, and soil was amended with varying amounts of olive pomace (0, 15, 30, 37.5%). These four mixtures, with a total of 2000g, were fed to 170 Eisenia fetida earthworms per mixture. Nitrogen adsorption-desorption, FT-IR, and elemental analyses analyzed samples collected from biomass at the end of 45 days. Results were evaluated to determine the effect of olive pomace on organic matter degradation and earthworm vitality. Nitrogen adsorption-desorption isotherms of feedstock revealed a decrease in void volumes, implying the formation of a compact structure with olive pomace addition. Vermicomposting of biomass enhanced biomass’s compactness, further validated by decreases in BET surface areas, pore sizes, and pore volumes. The 31% increase of earthworm biomass in the presence of 37.5% olive pomace implied an affinity of Eisenia fetida towards olive pomace. This finding was further validated by FT-IR peaks obtained at 2850 and 2923 cm-1, showing increased biomass aromaticity due to the degradation of readily biodegradable aliphatic structure introduced by olive pomace. Ongoing organic matter degradation could be observed with the decrease of C/N ratios in the presence of olive pomace as high as 15%. However, a further increase in olive pomace increased the C/N ratio, which was explained by the increase in total nitrogen values during vermicomposting. Elemental analyses evaluated regarding C/N, O/C, and H/C ratios also indicated increased earthworm mobility with increasing olive pomace in the feedstock. The results obtained in the study were interpreted to introduce olive pomace as a preferable nutrition source for earthworms, which was the highlight of the present study

Morphology controlled fabrication of porous magnesium oxide nanostructures for the efficient elimination of methyl orange

Abstract Magnesium oxide-based adsorbents (MGO-A) with different morphologies were synthesized via the hexamethylene tetramine-assisted hydrothermal method. The role of four anions in the reaction system, chloride (Cl⁻), nitrate (NO3 ⁻), sulfate (SO4 2⁻), and acetate (C2H3O2 2⁻) was systematically investigated to determine the properties of the MgO. Standard characterization techniques were used, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and surface area and pore size interpretations. The kinetics and adsorption isotherm were studied for removal of the dye methyl orange. The dye’s rapid removal led to equilibrium being reached within 5 min. The correlation coefficient values indicate more applicability of pseudo-second-order kinetics than the pseudo-first-order kinetics. Both physisorption and chemisorption can be a pathway towards successfully removing methyl orange. The adsorption isotherm shows that the maximum capacity of the material is very high, 1,062 mg/g for MGO-A. In light of these results, it appears this material holds promise as a dye removal material.

Enhanced sequestration of ciprofloxacin from aqueous solution using composite montmorillonite-kaolin clay adsorbent

Clay minerals are low-cost and environmentally benign natural adsorbents with huge potential for removing micropollutants from aqueous solutions owing to their intrinsic surface properties. In this study, montmorillonite and kaolin clay minerals were activated using NaNO3 and HNO3 to develop activated montmorillonite- kaolin clay composites (AMKCC) material for the sequestration of ciprofloxacin (CIP) from aqueous solution. The developed AMKCC was characterized using X-ray fluorescence (XRF), Brunauer-emmett-teller (BET), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The BET analysis reveals an improved BET surface area, pore volume and pore diameter of 139.13 m2/g, 0.17 cm3/g and 2.18 nm, respectively. At optimum conditions, pH (3.56), initial concentration (16.74 mg/L), time (77.9 mins) and adsorbent dosage (0.4 g), the percentage of ciprofloxacin removed from aqueous solution was 97 %. The adsorption of ciprofloxacin (CIP) using AMKCC was spontaneous, feasible, endothermic, and followed Freundlich isotherm with pseudo-second-order kinetics. The maximum monolayer adsorption capacity of AMKCC is 344.82 mg/g. The desorption studies revealed HCl as the best eluent for AMKCC regeneration. Therefore, AMKCC has considerable potential for the adsorption of pharmaceuticals from aqueous solution.

A three-dimensional unsteady flow of Casson nanofluid with suspension of microorganisms with variable thermal conductivity: A modified Fourier theory approach

The study of nanofluids is important due to valuable applications in drug delivery systems, thermal processes, solar management systems, microfluidic devices, extrusion phenomenon, chemical processes etc. The objective of current analysis is to investigates the enhanced thermal performances of magnetized Casson nanofluid with suspension of microorganisms. An unsteady periodically oscillating flow due to bidirectional moving porous surface have been considered. The analysis is subject to assumptions of variable thermal conductivity. The modelled problem is based on implementation of modified Fourier theories. The Buongiorno nanofluid model is used to predicts the significance of Brownian motion and thermophoresis effects. Chemical reaction species are also attributed. For solution methodology, homotopy analysis scheme is implemented. The convergence region is specified. The physical impact of problem is visualized. The significant applications of parameters have been focused. The claimed results offer significance in cooling systems, chemical reactions, air conditioning, solar thermal systems, automotive radiators, heat exchangers in power plants etc.

Layer-by-Layer Deposition of Kraft Lignin and PEDOT:PSS.

Kraft lignin (KL) is a sustainable carbon-based substance with a potential use in photovoltaic materials. However, its conductivity is low, but it can be improved via incorporation with a conductive polymer, such as poly(3,4-ethylene dioxythiophene) (PEDOT): poly(styrenesulfonate) (PSS). This study examines the factors affecting the interaction of KL and PEDOT:PSS (PS) in a solution state using a quartz crystal microbalance with dissipation (QCM-D) and a stagnation point refractometer (SPAR). The results confirmed that aqueous environments, e.g., pH and ionic strengths, considerably affected particle size and zeta potential of KL and PS due to protonation, deprotonation, particle aggregation, and charge screening. The polymers exhibited the largest adsorbed mass and thickness at pH 6 and 10 mM NaCl on a solid surface, which was attributed to the relatively linear structure of PEDOT chains, exposing more adsorptive sites for interaction with KL. A 10 mM NaCl concentration facilitated the screening of charges on PS and KL surfaces, diminishing repulsive forces and enabling hydrophobic and cationic-π interaction, which led to increased adsorption. Contact angle and SEM investigations of the adsorbed layer revealed the water contact angle increasing and the morphology changing from a smoother layer to a porous surface, providing further evidence of adsorption. Furthermore, the conductivity was improved by the introduction of a PS adlayer on ITO glass when it was sandwiched between KL adsorbed layers. These findings provide insight into KL and PS interaction and suggest that KL can be used with PS for conductive materials, such as photovoltaics, imparting the waterproofness of the films.

A polyhedron-based metal-organic framework with electronegative donor sites for efficient C2H6/C2H4 separation

Ethylene is an important chemical raw material which is widely used in the production of chemical fibers, plastics, rubber, coatings, as well as medicines, and its separation from the gas mixtures of C2H6/C2H4 is of great importance but a challenging task due to their similar physical properties and molecular dimensions. Herein, we report the C2H6 and C2H4 sorption studies on a robust anionic metal-organic framework (MOF) {(NH2Me2)[Co3(μ3OH)(TPT)(TZB)3](H2O)6(DMA)6}n (Co-MOF) formed by connection of Co3(OH) clusters by two N-rich organic ligands 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) and 4-(1H-Tetrazol-5-yl)benzoic acid (H2TZB). The prepared Co-MOF features a polyhedron stacking network structure composed of trigonal bipyramidal cages and octahedral cage which both contribute to a high C2H6 uptake capacity of 6.48 mmol/g and a decent C2H6/C2H4 selectivity of 1.54 at 298 K and 1 bar. Grand Canonical Monte Carlo (GCMC) simulation results agree well with the experimental tendency, both in the adsorption isotherms and sorption heats, which demonstrated that the suitable pore surfaces with electronegative donor sites generated multiple CH ⋅⋅⋅O/N and CH ⋅⋅⋅π interactions between the framework and C2H6, resulting in a stronger interaction between the MOF skeleton and C2H6 molecule than C2H4 as reflected by the dispersion-corrected density functional theory (DFT) calculation.

Petroleum Pitch-Derived Porous Carbon Materials as Metal-Free Catalyst for Dry Reforming of Methane.

Porous carbon materials have gained increasing attention in catalysis applications due to their tailorable surface properties, large specific surface area, excellent thermal stability, and low cost. Even though porous carbon materials have been employed for thermal-catalytic dry reforming of methane (DRM), the structure-function relationship, especially the critical factor affecting catalytic performance, is still under debate. Herein, various porous carbon-based samples with disparate pore structures and surface properties are prepared by alkali (K2CO3) etching and the following CO2 activation of low-cost petroleum pitch. Detailed characterization clarifies that the quinone/ketone carbonyl functional groups on the carbon surface are the key active sites for DRM. Density functional theory (DFT) calculations also show that the C=O group have the lowest transition state energy barrier for CH4* cleavage to CH3* (2.15 eV). Furthermore, the cooperative interplay between the specific surface area and quinone/ketone carbonyl is essential to boost the cleavage of C-H and C-O bonds, guaranteeing enhanced DRM catalytic performance. The MC-600-800 catalyst exhibited an initial CH4 conversion of 51% and a reaction rate of 12.6 mmolCH4 gcat.-1 h-1 at 800 °C, CH4:CO2:N2= 1:1:8, and GHSV = 6000 mL gcat.-1 h-1. Our work could pave the way for the rational design of metal-free carbon-based DRM catalysts and shed new light on the high value-added utilization of heavy oils.

Sequential release of vancomycin and BMP-2 from chitosan/nano-hydroxyapatite thermosensitive hydrogel for the treatment of chronic osteomyelitis

In this study, we developed scaffolds materials with microspheres to form a double sustained release system.Chitosan/nano-hydroxyapatite (CS-HA) was used as a drug carrier to construct a sustained-release system for Bone morphogenetic protein-2(BMP-2) and Vancomycin (VAN). Furthermore, VAN and BMP-2 loaded microspheres (Ms) were prepared by the emulsion ultrasonic method.The resultant composites were characterized by Scanning electron microscope (SEM), compressive strength, porosity, and biodegradation. The characterization results showed uniform porous and rough surface, enhanced thermal stability, and highest compressive strength ((1.912 ± 0.012) Kpa, the surface of the two microspheres was slightly folded and showed a regular spherical shape.The loading rate of BMP-2 was (59.611 × 10-4 ± 0.023 × 10-4)% and the encapsulation rate was (6.022 ± 0.005)%. The release rate of vancomycin and BMP-2 was 57.194% and 12.968% respectively. Osteogenic differentiation of Bone marrow mesenchymal stem cells (BMSCs) was confirmed by alkaline phosphatase quantification. The deposition of late osteogenic markers (calcium phosphates) detected by Alizarin red, which indicated extracellular matrix mineralization. The results showed that BMP-2/VAN in CS-HA hydrogel successfully achieved the sequential release of the double drugs, which could benefit bone regeneration.

Trace DNA and its persistence on various surfaces: A long term study investigating the influence of surface type and environmental conditions – Part two, non-metals

The work presented herein is the second part of a large-scale persistence project aimed at identifying trends in trace DNA persistence. This study aims to show how different environmental storage conditions and target surface characteristics influence the persistence of cellular and cell free DNA (cfDNA) over time. To eliminate variation within the experiment, we used a proxy DNA deposit consisting of a synthetic fingerprint solution, cellular DNA, and/or cfDNA. Samples were collected and analysed from eight non-metal surfaces over the course of 1 year (27 time points) under three different environmental storage conditions. The results of this experiment show that surface characteristics in conjunction with DNA type greatly influence DNA persistence. Variation in the amount of DNA recovered over time was greatly influenced by surface porosity. CfDNA persisted at significantly higher levels on non-porous surfaces, and cellular DNA persisted at higher levels on porous items. Furthermore, statistically significant differences in DNA persistence were found among the items classified as non-porous surfaces and among the items classified as porous surfaces. Additionally, this study showed that the sample storage environment had a larger impact on DNA persistence than previously observed for metal surfaces [1]. When considering DNA type, cellular DNA was shown to persist for longer than cfDNA and persistence as a whole appears to be better when DNA is deposited alone rather than in mixtures. Unsurprisingly, it was found that the amount of DNA recovered from trace deposits decreased over time. However, DNA decay is highly dependent on the surface type and exhibits higher variability at short time points and on porous surfaces. For each of the surfaces tested, DNA persisted 1 year past deposition (in some combination of DNA type and environmental condition), except for wood, on which DNA did not persist in any capacity past four months. This data is intended to add to our understanding of DNA persistence and the factors which affect it.

Architecturing ultra-stable multi-dimensional MXene/MAX self-supporting electrode anchored with Low-Pt for efficient hydrogen evolution reaction in harsh environments

The design of self-supporting structure is particularly important to improve the stability and electrochemical performance of hydrogen evolution reaction electrode. Here, a facile strategy for building novel ultra-stable 0D-2D-3D integrated self-supporting electrode with high conductivity, sufficient diffusion channels and large reactive surface area was proposed. In the heterostructure, 2D Ti3C2Tx flakes in-situ synthesized on 3D network porous Ti3AlC2 surface which provides the multiple reactive surface areas and aggregation resistance to facilitating 0D ultrafine Pt nanoparticles uniform anchorage. Combined with structural characterization and first-principles calculations revealed that, the highly dispersed ultrafine Pt synergistically coupling strong metal-support interactions creates a unique multifunctional catalytic interface with high stability and atomic utilization efficiency of Pt to promote the HER in acidic and seawater. The resultant self-supporting electrode (support 0.48 wt% Pt) exhibits much superior activity to 10 % commercial Pt/C (loaded on foam nickel) in 0.5 M H2SO4 (55 mV@10 mA cm−2) and simulate seawater (196 mV@10 mA cm−2) while reducing the Pt usage by 15 times. Meanwhile, the electrode also illustrates outstanding stability under high current densities (100 h@100 mA cm−2). This study provides a new design idea for developing integrated self-supporting catalytic electrodes to meet the durability of hydrogen evolution reaction applications in harsh environments.

Flux and fouling behavior during constant pressure sterile filtration of nanoemulsions

Nanoemulsions with droplet diameters from 20 to 200 nm have emerged as attractive adjuvants in the development of novel vaccines and as an advanced method of drug delivery for hydrophobic drugs. However, the large size of the nanoemulsion droplets leads to very low capacities during the final sterile filtration step used to ensure sterility of parenteral drug products. The objective of this study was to examine the sterile filtration of a model nanoemulsion made using squalene as the oil and Tween 20 and Span 85 as stabilizing surfactants. Data were obtained with different commercial sterile filters with different morphology and chemistry during constant pressure filtration. In each case, there was essentially no filtration until the transmembrane pressure exceeded a critical value related to the force required to push the deformable nanoemulsion droplets through the membrane pores. The filter capacity increased with increasing pressure, going from 700 g/m2 at 140 kPa to 1300 g/m2 at 280 kPa for a dual layer polyethersulfone sterile filter, with the flux decline well described by the complete pore blockage model. The dual layer asymmetric membranes showed much higher capacities than corresponding single layer filters due to the effectiveness of the upper layer in removing larger nanoemulsion droplets that would otherwise block the pores of the sterile filter. The capacity of the different sterile filters was also well-correlated with the initial filtrate flux, with both of these parameters governed by the pore size distribution and surface chemistry of the filters. These results provide important insights into factors controlling the sterile filtration of highly concentrated nanoemulsions used in the formulation of vaccines and drug products.