Mean Pore Diameter Research Articles

Effects of particle gradation and geometry on the pore characteristics and water retention curves of granular soils: a combined DEM and PNM investigation

Pore characteristics play central roles in the transport of water and gas through granular soils, which is relevant to a wide range of geotechnical and geoenvironmental applications. In this study, a numerical procedure combining the discrete element method and pore network model is presented to relate the physically representative pore structure to the particle geometric features, and rapidly predict the macroscopic flow properties of granular assemblies. This numerical procedure is applied to investigate the effects of particle gradation and geometry on the pore characteristics and water retention curves of granular soils under isotropic compression. The results indicate that a larger uniformity coefficient (Cu) of particle diameters results in a lower porosity. The porosity first decreases and then increases as the aspect ratio (AR) of the particles increases from 1.00 to 2.50 and reaches the minimum at AR = 1.75. As Cu ranges from 1.00 to 2.16, the standard deviations and mean values of pore geometry and connectivity parameters, including pore and throat diameters, pore spacings, and coordination numbers, present linear correlations. The logarithm of air entry pressure decreases linearly with the increasing logarithm of mean pore diameter in response to the variations in both Cu and AR. A higher pore diameter variance induced by a smaller Cu produces a lower fitting parameter m in the van Genuchten equation for water retention curves.

Effect of different concentrations of spraying chitosan solution on structure and properties of PVDF porous membrane

Polyvinylidene fluoride (PVDF) porous membranes were prepared by a two-step method of surface gelation-immersion precipitation phase inversion. The effects of spraying CS solution concentrations on the structure and properties of membranes were investigated. The results showed that with the concentration increasing of CS solution spraying on the surface of the casting solution film, the porosity of PVDF membranes gradually increased, the mean pore diameter of membranes firstly increased and then reduced, the surface contact angle decreased, and β crystal content in the top surface of membranes gradually decreased. The top surface of membrane without spraying CS solution displayed a dense structure, while the top surface of membranes after spraying CS solution exhibited a porous structure, while the cross-sectional structure of all membranes was composed of the finger-like voids. When the concentrations of spraying CS solution increased, the water flux of membranes firstly increased and then decreased.

Optimization of Activated Carbons Prepared from <i>Parinari macrophylla</i> Shells

Plant matter constitutes an important source for producing carbonaceous materials. This work deals with the preparation of active carbons from shells of Parinari macrophylla (agricultural waste in Niger). Physical, chemical and mixed activations are considered. Several parameters of preparation are optimized, as the nature of the activation gas (N2 or CO2, dry and wet), the concentration of the activating agent (H3PO4), the time of impregnation and the pyrolysis temperature program. The active carbons are characterized through their iodine numbers, their specific surface areas and their porous volumes. Active carbons, produced from shells of Parinari macrophylla display iodine numbers up to 599 mg I2/g and specific surface areas up to 727 m2/g. They also show microporous characteristics, with a mean pore diameter, usually, lower than 20 Å and a microporous surface percentage up to 88.7% and a microporous volume percentage up to 82.1%. The microporosity is far more developed for the active carbons produced by chemical activation.

Synthesis of TiO2 nanorods using wet chemical method and their photovoltaic and humidity sensing applications

In this work, synthesis of TiO2 nanorods using wet chemical method alongwith their photovoltaic and humidity sensing applications are reported. After successful synthesis of TiO2 nanorods, the material was investigated through X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. Surface morphology and topology of the synthesized nano material was analyzed by SEM showed porous and tubular structure. EDS confirmed the elemental composition. XRD revealed the rutile phase with minimum crystallite size as 78.60 nm. The optical characterization of nano material has been completed by using FTIR and UV–Vis spectroscopy to confirm the required bond formation and estimate the bandgap (5.86 eV) respectively. Brunauer–Emmett–Teller (BET) characterization exhibited the highly porous nature of the material revealing the surface area of 37.445 m2/g together with mean pore diameter ranging from 9 to 18 nm. Further, the material was employed as photovoltaic cell and humidity sensor. The photovoltaic efficiency was obtained as ∼0.3909% whereas sensitivity towards humidity as 2.93 pF/%RH and 0.42 MΩ/%RH for capacitance and impedance respectively at room temperature.

Acoustical absorptive properties of meltblown nonwovens for textile machinery

Noise pollution is one of the harmful physical sources in the textile industry, which is among those industries that are faced with noise exposure problems. The results of environmental sound measurements at modern textile mills have shown that the sound pressure level varied from 95 to 130 dB, where the highest sound pressure level was at weaving machines. Textile insulation materials can be fitted in order to decrease sound pollution at a low cost. The objective of this work is to design a sound absorber that can be fixed to the body of the machines, at the point of the noise generation, to reduce noise pollution. Poly(lactic acid) (PLA), which is an environmentally friendly material, was used to produce different samples of meltblown nonwoven absorbers to be used for damping the noise of textile machinery. PLA meltblown nonwoven fabric with the areal density of 16.7 g/m2, average fiber diameter of 1.1 µm, mean pore diameter of 9.8 µm and thickness of 0.27 mm exhibited significant sound absorption. The sample with the smallest average fiber diameter among those investigated had the highest damping effect: 23.95, 41.29 and 29.32 dBA at frequencies of 400, 1000 and 1500 Hz, respectively. Our goal is to have a practical tool that accurately evaluates the absorber sound damping under the actual running conditions of the textile machinery. The design of the absorber from one layer of the PLA meltblown nonwoven over a rigid polyurethane foam sheet had an excellent sound absorption property.

One-step engineering of low-cost kaolin/fly ash ceramic membranes for efficient separation of oil-water emulsions

Efficient construction of ceramic membranes can decrease the cost and ease the process of wastewater treatment. The total cost of ceramic membranes is mainly determined by the cost of raw materials and energy consumption during sintering process. In this work, fly ash particles recycled from electric plant and kaolin materials were respectively employed as the support and membrane layer of composite ceramic membranes. To match the sintering temperature of the kaolin material and fly ash support, rigid alumina particles were introduced into the supports (AFA supports). Also, the bending strength of the supports was improved when adding alumina particles. The kaolin/fly ash ceramic membrane was obtained by spraying the kaolin dispersion on the AFA supports and co-sintering. The mean pore diameter and water permeance of the membranes were 320 nm and 3650 Lm−2h−1 bar−1. When treating oil-water emulsions with oil content of 400 ppm, the oil removal rate was above 98.5% and the stable permeance was close to 530 Lm−2h−1 bar−1, likely due to the super-hydrophilic performance of kaolin and the electric repulsion between the membrane and oil droplets. The raw materials cost, sintering energy consumption, and fabrication time were successfully decreased. This work demonstrates the feasibility of low-cost ceramic membranes for efficient wastewater treatment in chemical industries.

Preparation of core-shell silica-carbon composite microspheres stationary phase and application in saccharide separation

In this study, core-shell mesoporous silica-carbon composite microspheres (Sil@MC) were prepared by one-step coating of the phenol formaldehyde polymer (PF) on SiO2 surface and by carbonizing the PF polymer under nitrogen atmosphere. The morphology observation of the Sil@MC stationary phase showed that it had good monodispersity. Surface area (302 m2/g), mean pore diameter (9.5 nm), and pore volume (0.63 cm3/g) of Sil@MC materials were also measured by pore structure analysis. The results showed that the Sil@MC was successfully immobilized on the silica particles via copolymerization and carbonization. As a stationary phase of HPLC, the Sil@MC column was filled by a slurry method. The Sil@MC materials formed after calcination of SiO2 coated with phenolic resin could be used for the separation of four polar sugar compounds (D-(+)-glucosamine hydrochloride, glucose, D-(+)-trehalose dihydrat and raffinose) with the mobile phase of acetonitrile-water (containing 0.1% (v/v) formic acid). However, the material formed by calcinating SiO2 without coating phenolic resin could not separate these polar sugar compounds by HPLC-MS. Finally, the representative oligosaccharide isomers of raffinose, melezitose and stachyose, nystose, and human milk oligosaccharide isomers, such as 3'-sialyllactose, 6'-sialyllactose and lacto-N-newtetraose, lacto-N-tetraose, were successfully separated by the Sil@MC column with good peak shapes. The results demonstrates that silica-carbon composites derived from phenolic resin have potential application in polar compounds chromatographic separation.

Fabrication of 3D hybrid scaffold by combination technique of electrospinning-like and freeze-drying to create mechanotransduction signals and mimic extracellular matrix function of skin

Fabrication of extracellular matrix (ECM)-like scaffolds (in terms of structural-functional) is the main challenge in skin tissue engineering. Herein, inspired by macromolecular components of ECM, a novel hybrid scaffold suggested which includes silk/hyaluronan (SF/HA) bio-complex modified by PCP: [polyethylene glycol/chitosan/poly(ɛ-caprolactone)] copolymer containing collagen to differentiate human-adipose-derived stem cells into keratinocytes. In followed by, different weight ratios (wt%) of SF/HA (S1:100/0, S2:80/20, S3:50/50) were applied to study the role of SF/HA in the improvement of physicochemical and biological functions of scaffolds. Notably, the combination of electrospinning-like and freeze-drying methods was also utilized as a new method to create a coherent 3D-network. The results indicated this novel technique was led to ~8% improvement of the scaffold’s ductility and ~17% decrease in mean pore diameter, compared to the freeze-drying method. Moreover, the increase of HA (>20wt%) increased porosity to 99%, however, higher tensile strength, modulus, and water absorption% were related to S2 (38.1, 0.32 MPa, 75.3%). More expression of keratinocytes along with growth pattern similar to skin was also observed on S2. This study showed control of HA content creates a microporous-environment with proper modulus and swelling%, although, the role of collagen/PCP as base biocomposite and fabrication technique was undeniable on the inductive signaling of cells. Such a scaffold can mimic skin properties and act as the growth factor through inducing keratinocytes differentiation.

Non-Destructive Characterization of Industrial Membrane Cartridges by Using Liquid-Liquid Displacement Porosimetry (LLDP).

This works aims to propose and demonstrate the accuracy of a novel method of characterization aimed for non-destructive analysis of microfiltration (MF) membrane cartridges. The method adapts conventional liquid–liquid displacement porosimetry (LLDP) for performing an in-line porosimetric analysis of the membrane cartridges, getting their pore size distributions (PSDs) and mean pore diameters (davg). Six commercial filtration cartridges featuring polyethersulfone (PES) pleated membranes were analyzed using a newly designed filtration rig, based on the liquid–liquid displacement porometer, developed at the Institut de la Filtration et des Techniques Séparatives (IFTS) and operated at constant flow. The experimental rig allows the direct and non-destructive characterization of the cartridge in its original presentation. Results have been compared with those obtained by using gas–liquid displacement porosimetry (GLDP) on small membrane coupons detached from such cartridges. The comparison allows us to conclude that the proposed method gives enough accuracy in the determination of porosimetric characteristics of the filters. This method can be used as a precise characterization technique for a non-destructive in-line study of filter performance and can be envisaged as useful to periodic quality or fouling control of the commercial cartridges.

Superhydrophilic and underwater superoleophobic nano zeolite membranes for efficient oil-in-water nanoemulsion separation

Nano zeolite-Y ultrafiltration (UF) membrane, with mean pore diameter of 28 nm was fabricated using a simple isostatic pressing technique. Zeolite-Y has preferential water pathways and a unique 3-D microporous structure. The zeolite-Y used in this study has an Al to Si (Al/Si) ratio of 0.07 which renders the membrane superhydrophilic with complete wetting of water in air. Whereas, when it is underwater, the membrane is superoleophobic with a contact angle of 156°. This study compared membranes with two different zeolite particle sizes, above and below 100 nm for their membrane morphology, and wetting properties, directly affecting the separation of oil-in-water separation. The membrane separation capabilities were tested for 600 mg/L of xylene, motor oil and crude oil mixture in water. There are limited studies on treating oil/water mixtures having nanoemulsions with stand-alone zeolite membranes, and thus this study provides a deeper insight on utilizing such a ceramic material for improved separation processes.A flux of 45−70 L/m2.h was obtained for the nano-zeolite membrane, depending upon the type of oil, with the motor oil giving the lowest flux due to its heavy components. The nano-zeolite membranes produced ∼ 20 % higher flux than the micro-zeolite membrane at a membrane pressure of 70 kPa. A higher flux was attributed to the higher membrane porosity and favored nano-channel pathways along the zeolite pores for the water molecules. In addition, oil rejections as high as 99.8 % with oil content as low as 1.57 ± 0.2 mg/L were obtained. Thus, the membrane was found to be very effective in nanoemulsion oil-water separation owing to its exceptional structural properties and superoleophobicity of oil under water.

“Compulsory co-precipitation”, a novel and rational route for the synthesis of nanomaterials; mesoporous zinc sulfide as the first case

In the present research work, a novel approach named as compulsory co-precipitation has been introduced for the synthesis of nanoparticles. In this approach a liquid in which the precursors of the target chemical compound are insoluble has been selected as the media of the synthesis reaction. Compulsory co-precipitation was employed for the synthesis of mesoporous zinc sulfide (ZnS) particles which normally were synthesized in the soluble atmospheres. The mesoporous ZnS particles with relatively large surface area were synthesized in the cyclohexane atmosphere as a non-solvent reaction media for Zn(NO3)2·6H2O and Na2S·5H2O precursors. Successful synthesis of cubic zinc blende ZnS particles was confirmed by X-ray diffraction (XRD) analysis. Nitrogen adsorption-desorption analysis was exploited to elucidate the surface porosity characteristics of the particles. The results validated the formation of a mesoporous structure with the maximum specific surface area of about 191 m2 g−1, mean pore diameter of 2.6 nm, and pore volume of about 0.12 cm3 g−1. Forced solution of Zn2+ and S2− as a result of ultrasonic irradiation followed by immediate precipitation of the synthesized ZnS particles was proposed as the ZnS formation mechanism. Also the removal the by-product of the synthesis reaction during the post synthesis treatments was suggested as the main factor for the induction of porosity in the ZnS structure.

Mesoporous carbon nanospheres derived from agro-waste as novel antimicrobial agents against gram-negative bacteria.

Porous carbon nanospheres were synthesized from agro-waste garlic peels by a one-pot facile and easy to scale-up pyrolysis method. Surface morphology and structural features of the nanospheres have been studied by field emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and Raman spectroscopy. Fourier transform infrared spectroscopy (FTIR) and N2 adsorption desorption experiments were explored to detect surface functionality, surface area, and porosity. Average particle diameter of the synthesized nanospheres was 31 ± 6.3nm and zeta potential of - 25.2mV ± 1.75mV. Nanoscale carbon was mesoporous in nature with type IV isotherms, mean pore diameter of 15.2nm, and total pore volume of 0.032cm3/g. Minimum inhibitory concentration and minimum bactericidal concentration values of carbon nanospheres against Escherichia coli are 480 ± 0.5μg/ml and 495 ± 0.5μg/ml, respectively. Synthesized nanospheres exhibited gram-selective antimicrobial action against Escherichia coli probably linked to membrane deformity due to interaction of nanocarbon with the bacterial membrane. Carbon nanospheres resulting from waste to wealth transformation emerged as promising candidates for antibacterial application. Graphical abstract.

Surface Characteristics and Rose Bengal Adsorption Studies of Carbon Nanospheres Synthesized via Atmospheric Combustion of Diesel

In this study, the carbon nanospheres were synthesized by burning diesel and then treated with hydrogen peroxide (H2O2). The results showed that H2O2 - carbon nanospheres has a higher surface area than carbon nanospheres and therefore it was chosen as an adsorbent surface to remove the Rose Bengal dye from aqueous solutions. The prepared carbon nanospheres were examined by FTIR, XRD, SEM, AFM, TGA, Raman spectroscopy, BET and EDX. The FTIR study reveals the presence of hydroxyl and carboxyl stretching vibration and weak peaks belong to CH3, CH2 and C=C. Results obtained by Raman and XRD analysis are in good agreement thereby indicating the amorphous structure of the carbon nanospheres. Also, SEM images confirm the presence of soot materials as spherical and semispherical nanoparticles with diameter in the range (31-78 nm). Surface roughness calculated from AFM data provided evidence that spiky appearance on both carbon surfaces. TGA data indicate that both carbon samples are thermally unstable. BET and BJH results indicate that the treated sample possesses the highest surface area and mean pore diameter. EDX analysis indicated the presence of pure carbon nanosphere (treated sample) without any contamination. Also, the adsorptive removal of Rose Bengal on synthesized carbon nanospheres was studied. The isotherm adsorption results were found to be described fitted by the Freundlich rather than the Langmuir and Temkin models. Furthermore, the kinetics of dye adsorption were applied better by the pseudo-second-order model.

Preparation and Characterisation of Activated Carbon from Palm Mixed Waste Treated with Trona Ore.

This study explores the use of a novel activating agent and demonstrates the production and characterisation of activated carbon (AC) from a combine palm waste (CPW) in 3:2:1 proportion by weight of empty fruit bunch, mesocarp fibre and palm kernel shell. The resulting biomass was processed by a microwave-assisted method using trona and compared with material produced by conventional routes. These results demonstrate the potential of trona ore as an activating agent and the effectiveness of using a combined palm waste for a single stream activation process. It also assesses the effectiveness of trona ore in the elimination of alcohol, acids and aldehydes; with a focus on increasing the hydrophilicity of the resultant AC. The optimum results for the conventional production technique at 800 °C yielded a material with SBET 920 m2/g, Vtotal 0.840 cm3/g, a mean pore diameter of 2.2 nm and an AC yield 40%. The optimum outcome of the microwave assisted technique for CPW was achieved at 600 W, SBET is 980 m2/g; Vtotal 0.865 cm3/g; a mean pore diameter 2.2 nm and an AC yield of 42%. Fourier transform infrared spectrometry analyses showed that palm waste can be combined to produce AC and that trona ore has the capacity to significantly enhance biomass activation.

A novel reduced graphene oxide based absorber for augmenting the water yield and thermal performance of solar desalination unit

The absorber plate of a single basin solar still (SS) is coated by black paint doped with reduced graphene oxide (RGO) nanosheet having a mass fraction of 4–12 wt%, to augment the water yield. The RGO was prepared through hydrothermal treatment to have a specific surface area and mean pore diameter of 167.72 m2.g−1 and 22 nm, respectively. The utilization of 12 wt% RGO doped with black paint-coated absorber enhances the water and absorber temperature by 14.7 and 15.7%, respectively, as compared to only black paint-coated absorber. The accumulated water yield of the SS with (12 wt%) and without the RGO coating was found to be 5.59 and 3.96 L/m2/day, respectively.

Biological and structural properties of graphene oxide/curcumin nanocomposite incorporated chitosan as a scaffold for wound healing application

AimsThe purpose of this research is to fabricate chitosan (CS)/graphene oxide (GO)/curcumin (Cur) 3D scaffolds through the freeze-drying method for wound dressing applications. Main methodsGO is produced by Hammer's method; then, it is characterized by X-ray diffraction and TEM analysis. Fabricated scaffolds are characterized by FTIR, FESEM, AFM, water vapor transmission rate, PBS absorption, contact angle, tensile strength, porosity measurement, biodegradability, and drug release methods. The cell viability and morphology of NIH/3 T3 cells are investigated by WST assay kit and FESEM analysis, and the antibacterial activity of scaffolds is determined by the optical density (OD) method. The photothermal antibacterial activity is characterized by NIR irradiation, too. Key findingsThe mean pore diameter of scaffolds adjusted by the incorporation of about 0–1.5%wt. of GO/Cur nanocomposite into CS matrix, decreasing from 87 to 40 μm that can be attributed to the intermolecular bonds between CS and GO/Cur nanocomposite. Besides, the PBS absorption of scaffolds enhances by the addition of GO/Cur, especially 1% of it. Furthermore, the overall average of cell viability of nanocomposite scaffolds is about 95%, and the FESEM images show that NIH/3T3 fibroblasts well spread on the nanocomposite scaffolds. GO/Cur has a significant influence on the antibacterial activity of CS scaffolds as CS/GO/Cur 0.5 scaffold diminishes the bacterial growth to about 52% of the control sample's growth. SignificanceThe results evidence the antibacterial CS/GO/Cur scaffolds are excellent supports for cell growth and proliferation, and they could be promising candidates for wound dressing applications.

Double diamond structured bicontinuous mesoporous titania templated by a block copolymer for anode material of lithium-ion battery

Titania has received considerable attention as a promising anode material of Li-ion battery (LIB). Controlling the structure and morphology of titania nanostructures is crucial to govern their performance. Herein, we report a mesoporous titania scaffold with a bicontinuous shifted double diamond (SDD) structure for anode material of LIB. The titania scaffold was synthesized by the cooperative self-assembly of a block copolymer poly(ethylene oxide)-block-polystyrene template and titanium diisopropoxide bis(acetylacetonate) as the inorganic precursor in a mixture solvent of tetrahydrofuran and HCl/water. The structure shows tetragonal symmetry (space group I41/amd) comprising two sets of diamond networks adjoining each other with the unit cell parameter of a = 90 nm and c = 127 nm, which affords the porous titania a specific surface area (SSA) of 42 m2·g−1 with a mean pore diameter of 38 nm. Serving as an anode material of LIB, the bicontinuous titania scaffold exhibits a high specific capacity of 254 mAh·g−1 at the current density of 1 A·g−1 and an alluring self-improving feature upon charge/discharge over 1,000 cycles. This study overcomes the difficulty in building up ordered bicontinuous functional materials and demonstrates their potential in energy storage application.

A model for the conduction shape factor in spherical void phase porous materials

This article presents a method for determining the conduction shape factor for complex porous media by performing pore-level simulations on the solid phase of mathematically-generated geometric models. The shape factor is a geometric property and does not depend on the thermophysical properties of the material or the interstitial fluid. The shape factor is established for several geometric variations of permeable, spherical-void-phase porous materials using a direct computational approach and it is shown that there is a dependency on both the porosity and pore diameter. We also show that the shape factor can be characterized by a quadratic expression that is in terms of porosity and mean pore diameter. The results are validated directly by comparing computations of conjugate heat transfer done using pore-level and volume-averaged approaches.

Inclusion of sulfamethoxazole in a novel CuFe2O4 nanoparticles/mesoporous silica‐based nanocomposite: Release kinetics and antibacterial activity

In this work, we aimed to improve the antibacterial activity of sulfamethoxazole (SMX) via its inclusion in a newly synthesized nanocomposite composed of CuFe2O4 nanoparticles and poly(vinyl alcohol)/silica‐based mesoporous materials. Characterization of this formulation using different techniques confirmed the correct synthesis and showed that this mesoporous nanocomposite had an amorphous structure with relatively high surface area of 1,620.7 m2 g−1 and mean pore diameter of 1.6576 nm. Zeta potential of the formulation was obtained to be zero which led to its higher bioavailability in comparison to pure SMX with negative zeta potential. Antibacterial property of the prepared formulation against Staphylococcus aureus and Escherichia coli was evaluated. Minimum inhibitory concentration of the SMX‐loaded mesoporous nanocomposite was considerably lower than those of pure SMX, indicating the efficient function of the mesoporous material as a delivery system. Kinetics of SMX release was also studied using zero‐order, first‐order, Higuchi, and Korsmeyer–Peppas kinetics models. According to the obtained results, the release kinetics was found to obey zero‐order model. So the possibility of sustained release of SMX from the synthesized carrier may be suggested.

Green production of cellular ceramics by emulsification of sunflower oil followed by gelcasting and starch consolidation

An environmentally friendly process combination for the production of alumina-based cellular ceramics is proposed. Biodegradable, renewable additives and low-energy conditions were applied. A fractional factorial design of 2 (4–1) + 3C was used to study the influence of gelatin, starch, and solids concentration, as well as water:oil ratio, on the rheological behavior of the suspension, and microstructural and mechanical features of cellular ceramics. A deflocculation curve was elaborated to define the best deflocculant concentration. The emulsions presented a rheopectic and pseudoplastic behavior. The sample with the highest open porosity was selected and analyzed by computer microtomography. SEM images showed open and closed spherical pores in the range of 7–22 μm for samples sintered at 1400 oC; 6–17 μm at 1550 °C, with respective open porosity values of 36–59% and 23–58%. Mean pore diameters estimated by μCT varied from 2 to 14 μm, with 78% at 1400 oC and 89% at 1550 oC. Compressive strength measured were 16–57 MPa (1400 oC), and 40–78 MPa (1550 oC). The combination of the three manufacturing methods was effective in the production of cellular ceramics with low energy, low amounts of gelling agents and low environmental costs.