Surface Pore Research Articles

Pore Structure and Heterogeneity Characteristics of Coal-Bearing Marine–Continental Transitional Shales from the Longtan Formation in the South Sichuan Basin, China

Marine–continental transitional shale has become a new field for shale gas exploration and development in recent years. Its reservoir characteristics analysis lags significantly behind that of marine shale, which restricts the theoretical research on the accumulation of marine–continental transitional shale and the progress of exploration and development. The shale pore system is complex and has strong heterogeneity, which restricts the fine evaluation and optimization of the reservoir. Based on nitrogen adsorption–desorption experiments, the morphology and structural characteristics of coal-bearing shale pores were analyzed, and then the micro-pore structure heterogeneity was quantitatively characterized based on fractal theory and nitrogen adsorption–desorption data, and the relationship between pore structure parameters and their influence on fractal characteristics were discussed. The hysteresis loop of nitrogen desorption isotherm mainly belongs to type B, indicating ink bottle, flat plate, and slit are the main pore shapes. The pore size distribution curves are left unimodal or multimodal, with the main peak around 4 nm and 20–60 nm. Smaller pores develop a larger specific surface area, resulting in a high value of fractal dimension (2.564 to 2.677). The rougher the pore surface and the larger the specific surface area provide an adequate adsorption site for shale gas adsorption and aggregation. Thus, fractal characteristics conduced to understand the pore structure, heterogeneity, and gas-bearing property of coal-bearing shale.

Investigation of the shape-changing property of X-ray computed tomography in the evaluation of pores

Porosity in additive manufacturing is one of the main quality characteristics for components. In processes such as laser-based powder bed fusion of metals (LPBF-M), correlations can be observed between the process parameters used, such as laser power, hatch distance or layer thickness, and the pore shape produced. Therefor the surface depending criterion sphericity is a crucial parameter for the classification of pores. In addition to methods like micrographs or Archimedes' density determination, industrial X-ray computed tomography (CT) is a key measurement method for the spatial but also shape-dependent assessment of pores in components. However, due to the lack of standards, no measurement uncertainty for shape, position, and volume can be given for CT measurements. With the help of CT simulations and models for detector and X-ray source to real CT system, investigations can be made on the dependencies and influence on the detectability of pores. This study shows that the CT measurements as well as the analysis have an influence on the detectable volume and surface of pores. By modelling pore models with cosine periodic spatial frequencies (peaks), the spatial influence of CT on detectability can be investigated and assessed as a form of slope distribution. The simulation-based measurement uncertainty information can be used to improve the separation of pore shape classifications and thus contribute to the development of additive manufacturing.

Doping of photoactive TiO2 films by DC plasma electrolytic oxidation: Effect of transition metals

Several beneficial features maintain TiO2 in the top list of viable materials for photocatalytic purposes. However, its relatively large band-gap (3.0–3.2 eV) still hampers practical applications under sunlight. This work explores Direct Current (DC) Plasma Electrolytic Oxidation (PEO) of titanium as a fast, easily-scalable and single-step tool to synthesise doped TiO2 photoanodes with controlled morphology, crystalline structure and thickness. Zn-, Cu- and Fe-doped crystalline TiO2 films were obtained in H2SO4 aqueous solutions containing ZnSO4, CuSO4 and FeSO4 precursors, respectively. As-prepared TiO2 films showed a porous and homogeneous sponge-like surface morphology, typical of PEO-produced oxides, and a crystalline phase structure consisting of a mixture of anatase and rutile phases. The anatase content varied in the 54–100 % range and correspondingly the band-gap energy was in the 2.85–3.07 eV range. Doped oxides prepared with a low concentration of the metal precursors showed monochromatic incident-photon-to-current-efficiency (IPCE) values exceeding those obtained with pristine TiO2 by up to 24 %, best performing in the order Zn- > Cu- > Fe-doped TiO2. Photocurrent under polychromatic UV-Vis irradiation showed an analogous trend and the estimated efficiency of solar-light harvesting was in the 0.3–4 % range, with Zn- ≈ Cu- > Fe-doped TiO2. Although the superior performance of the PEO-prepared metal-doped TiO2 could not be fully confirmed by photoelectrocatalytic oxidation tests of organics, the present investigation showed the viability of DC PEO for the synthesis of metal-doped TiO2 photoanodes.

Impact of the support material on the phosphorus poisoning on Co-based catalysts for Fischer-Tropsch synthesis

The role of the support on the poisoning by phosphorus of cobalt-based catalysts for the Fischer-Tropsch synthesis was investigated. Four different supports were used in this study, γ-alumina, titania and two silica gels with different pore sizes and surface areas. The deactivation varies in intensity depending on the type of support. The trend follows the strength of the metal-support interactions, γ-alumina being the least affected, while SiO2 (2 samples with different pore structures) was most affected. These results suggest that in the first case, P interacts mainly with the support while with less interacting supports, P will interact more with the cobalt particles. The addition of different loadings of P was done after the preparation of the catalysts simulating the possible behaviour of a Biomass to Liquids process. The P loading resulted in a decrease in site-time yield and a higher hydrogenation activity leading to a reduced production of value products. Conventional characterization of the catalysts showed two different deactivation mechanisms, including site blocking and electronic effects. The addition of phosphorus decreased the metallic dispersion and reducibility of the catalysts, inhibited the hydrogen desorption and reduced the CO adsorption. Phosphorus species might be altering the catalyst surface, yielding a higher H2/CO ratio adsorbed on the catalyst through the modification of the bonding strength between the cobalt and CO, and preventing the desorption of H2.

An investigation for optical, photocatalytic, photoluminescence and dielectric properties of Cd0.40Ni0.60ZnO2 annealed nanocomposites

We report here the optical, photoluminescence (PL), and dielectric properties of Cd0.40Ni0.60ZnO2 nanocomposites annealed between 200 and 600oC. An increase in annealing temperature (Tann) up to 600oC correlates with a gradual increase in the crystallite and particle sizes. The surface area, pore radius, and pore volume are increased as Tann increases from 200oC to 300oC, and then decreased, but still higher than of 200oC. Similar behaviors were obtained for the absorbance carrier density, photocatlytic efficiency, degradation rate, PL intensity, dielectric constant, dielectric loss, ac conductivity, F-factor, series resistance, and electronic polarizability. While the energy gap, binding energy, impedance of grains and their boundaries, and effective capacitance show an opposite behavior. The relaxation times at the peak of dielectric parameters are between 11.54 and 159.24ns and between 35.23 and 24273.73ns, respectively. The Cole-Cole plot shows a single semicircle at Tann < 400oC and two successive semicircles at Tann> 500oC. The energy of PL of visible emissions is independent on the chosen Tann. These findings indicated that the nanocomposite annealed at 300oC can be used for water purification, telecommunications, solar cells, supercapacitor, and white light-emitting diodes (LEDs).

Efficient adsorptive removal of 2,4-dichlorophenoxyacetic acid (2,4-D) using biomass derived magnetic activated carbon nanocomposite in synthetic and simulated agricultural runoff water

This study focused on evaluating the efficacy of a magnetic activated carbon material (CPAC@Fe3O4) derived from pods of copper pod tree in adsorbing the toxic herbicide, 2,4- (2,4-D) from aqueous solutions. The synthesized CPAC@Fe3O4 adsorbent, underwent various characterization techniques. FESEM images indicated a rough surface, incorporating iron oxide nanoparticles, while EDS analysis confirmed the presence of elements like Fe, O, and C. Notably, the CPAC@Fe3O4 exhibited high surface area (749.10 m2/g) and pore volume (0.5351 cm³/g), confirming its mesoporous nature. XRD investigations identified distinct signals associated with graphitic carbon and magnetite nanoparticles, while VSM analysis verified its magnetic properties with a high magnetic saturation value (2.72 emu/g). The adsorption process was exothermic, with a decrease in adsorption capacity at higher temperatures. Freundlich isotherm provided the best fit for the adsorption, and the pseudo-second-order equation effectively described the kinetics. Remarkably, the maximum adsorption capacity ranged from 246.43 to 261.03 mg/g, surpassing previously reported values. The ΔH° value (−8.67 kJ/mol) suggested a physisorption mechanism, and the negative ΔG° values established the spontaneous nature. Furthermore, the synthesized adsorbent demonstrated exceptional reusability, allowing for up to five cycles of adsorption-desorption operations. When applied to simulated agricultural runoff, CPAC@Fe3O4 showcased a significant adsorption capacity of 160.71 mg/g for 50 mg/L 2,4-D, using a 0.2 g/L dosage at pH 2. This study showcased the transformation of copper pod biomass into a valuable magnetic nanoadsorbent capable of efficiently eliminating the noxious 2,4-D pollutant from aqueous environments.

Synthesis of Mesoporous Silica from Palm Oil Boiler Ash (MS-POBA) with Addition of Methyl Ester Sulfonate as a Template for Free Fatty Acid Adsorption from Crude Palm Oil (CPO)

The synthesis of mesoporous material by utilizing palm oil boiler ash (POBA) waste as the silica source and methyl ester sulfonate (MES) surfactant as the template for a high-porosity was investigated for free fatty acids (FFA) adsorption. The research was initiated with silica extraction from POBA by sodium hydroxide addition through the sol-gel precipitation method. Silica modification was carried out with MES surfactant and 3-aminopropyltrimethoxysilane (APTMS) as the co-structure-directing agent (CSDA) in different calcination temperatures. Mesoporous silica-POBA (MS-POBA) free template had a surface area, pore diameter, and pore volume (41.033 m2/g, 4.180 nm, and 0.250 cm3/g) lower than MS-POBA with the template (71.0147 m2/g, 7.923 nm, and 0.524 cm3/g). The ability of MS-POBA to adsorb FFA reached its optimum conditions with an adsorption time of 20 min and an adsorbent dosage of 0.24 g. The FFA removal by MS-POBA with the template was found to have higher adsorption ability, which was 35.54%, compared to the MS-POBA free template of 26.68%. The high porosity of MS-POBA with a template makes the FFA adsorption capacity of this material higher than MS-POBA free template.

Algae Derived Carbon from Hydrothermal Liquefaction as Sustainable Carbon Electrode Material for Supercapacitor

With the worldwide awareness of sustainability, biomass-derived carbon electrode materials for supercapacitors have attracted growing attention. In this research, for the first time, we explored the feasibility of making use of the carbon byproduct from hydrothermal liquefaction (HTL) of microalgae, termed herein as algae-derived carbon (ADC), to prepare sustainable carbon electrode materials for high-performance supercapacitor development. Specifically, we investigated carbon activation with a variety of activating reagents as well as N- and Fe-doping of the obtained ADC with the intention to enhance its electrochemical performance. We characterized the structure of the activated and doped ADCs using scanning electron microscope (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and BET surface area and pore analysis, and correlated the ADCs’ structure with their electrochemical performance as evaluated using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), impedance, and cycle stability through an assembled symmetric two-electrode cell with 1 M H2SO4 as electrolyte. It was found that the ADC that is activated using KOH (KOH-ADC) showed the best electrochemical performance, and its specific capacitance was 14.1-fold larger with respect to that of the raw ADC and reached 234.5 F/g in the GCD test at a current density of 0.5 A/g. The KOH-ADC also demonstrated excellent capacitance retention (97% after 10,000 cycles at a high current density of 10 A/g) for stable long-term operations. This research pointed out a promising direction to develop sustainable electrode materials for supercapacitors from the carbon byproduct produced after HTL processing of algae.

Freeze-Thaw Cycle Durability and Mechanism Analysis of Zeolite Powder-Modified Recycled Concrete.

The inferior mechanical performance and freeze-thaw (FT) resistance of recycled concrete are mostly due to the significant water absorption and porosity of recycled coarse particles. In this study, different dosages of zeolite powder were used in recycled concrete. A series of macroscopic tests were used to evaluate the workability and FT durability of zeolite powder-modified recycled concrete (ZPRC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to reveal the micro-mechanisms of FT resistance in ZPRC. The results show that the increase in zeolite powder content leads to a decrease in the slump and water absorption of ZPRC. Additionally, ZPRC with 10% zeolite powder has superior mechanical characteristics and tolerance to FT conditions. The higher strength and FT resistance of the ZPRC can be attributed to the particle-filling effect, water storage function, and pozzolanic reaction of zeolite powder, which results in a denser microstructure. The particle-filling effect of zeolite powder promotes the reduction of surface pores in recycled coarse aggregates (RCAs). The water storage function of zeolite powder can provide water for the secondary hydration of cement particles while reducing the free water content in ZPRC. The pozzolanic reaction of zeolite powder can also promote the generation of hydrated calcium silicate and anorthite, thereby making the microstructure of ZPRC more compact. These results provide theoretical guidance for the engineering application of recycled concrete in cold regions.

In vitro and in vivo degradation profile, biocompatibility of poly-L-lactic acid porous microspheres

The objective of this study is to evaluate the in vitro and in vivo degradation profile and biocompatibility of poly-L-lactic acid (PLLA) porous microspheres (PMs) for their potential application as injectable microcarrier or micro-scaffolds materials in the research and clinical use of craniofacial cartilage repair. In this study, PLLA PMs prepared exhibited spherical shape and uniform surface pores followed by 24-week evaluations for degradation behavior and biocompatibility. In vitro degradation analysis encompassed morphological examination, pH monitoring, molecular weight analysis, thermodynamic assessment, and chemical structure analysis. After 12 weeks of in vitro degradation, PMs maintained a regular porous spherical structure. Molecular weight and glass transition temperature of PLLA PMs decreased over time, accompanying with an initial increase and subsequent decrease in crystallinity. Enzymatic degradation caused morphological changes and accelerated degradation in the in vitro studies. Finally, in vivo evaluations involved subcutaneous implantation of PLLA PMs in rats, demonstrating biocompatibility by enhancing type I and type III collagen regeneration as observed in histological analysis. The results demonstrated that PLLA PMs were able to maintain their spherical structure for 12 weeks, promoting the generation of collagen at the implantation site, meeting the time requirements for craniofacial cartilage repair.

Hot injection synthesis of CuS decorated CdS and ZnS nanomaterials from metal thiosemicarbazone complexes as single source precursors: Application in the photocatalytic degradation of methylene blue

CdS and ZnS are considered excellent semiconductors for photocatalysis, but photocorrosion and low photocatalytic activity limit their practical application. In order to improve on their photocatalytic activities, Copper sulfide-decorated CdS and ZnS (CuS@CdS and CuS@ZnS) nanocomposites were synthesized from Cu(II), Zn(II) and Cd(II) complexes of 2–(phenyl(pyridin–2–yl)methylene)hydrazine–1–carbothioamide, as single source precursors using a facile hot injection method at 250 °C, employing olive oil as capping agent. The structure, morphology, and optical properties of the as-prepared nanocomposites were determined using various analytical techniques. The results of powder X-ray diffraction (p-XRD), energy dispersive X-ray spectroscopy (EDX) and elemental mapping showed the presence of CuS, CdS and ZnS in CuS@CdS and CuS@ZnS, confirming the formation of nanocomposites. Transmission Electron Microscopy (TEM) images show agglomeration of CuS nanoparticles on the surface of CdS and ZnS nanoparticles. Scanning electron microscopy (SEM) images of CuS@CdS and CuS@ZnS nanocomposites revealed an agglomerated flower-like structure with porous surface. The band gap energies of 2.84 eV and 3.12 eV for CuS@CdS and CuS@ZnS, respectively, obtained from Tauc plots, demonstrate that combining CuS with single CdS and ZnS has an effect on their optical properties which probably account for the improved photocatalytic responses. The photocatalytic performance of the as-prepared materials was evaluated using the photodegradation of methylene blue (MB) dye under UV light irradiation. Results show that the degradation efficiencies for CuS@CdS (57 %) and CuS@ZnS (65 %) nanocomposites exhibited higher photocatalytic activity compared to those of pure CuS (42.0 %), CdS (35.1 %) and ZnS (57 %), suggesting that thiosemicarbazone complexes can be used as precursors for the development of metal sulphide nanocomposites as useful photocatalysts for the degradation of organic pollutants.

Comprehensive characterization of microcrystalline cellulose from lemon grass (Cymbopogan citratus) oil extraction agro-industrial waste for cementitious composites applications

Presently, the construction industry demands components that are exceptionally strong and long-lasting. The initial important construction material is concrete, which contains between 1 % and 2 % of air voids. The structural damage caused by water that enters through the air spaces are improved with filler material. Chemical filler materials are environmentally harmful; therefore, eco-friendly materials are selected for this study. The environmentally benign character of agro-waste byproduct usage is a driving factor in the field of research. Numerous uses can be found for waste materials, especially after they have been repurposed. We used a byproduct of an essential oil extraction company, an extract made from the leaves of lemon grass (Cymbopogan citrus), in our research. Alkalization, slow pyrolysis, acid hydrolysis, and bleaching are only some of the chemical treatments that could be used to easily extract microcrystalline cellulose from the discarded waste material. In our study the chemicals used are mild harmful to the environment and a surface reactant (linear alkyl benzene sulfonic acid) is utilised to bleach and purify the microcrystalline cellulose. Thermal analysis, scanning electron microscopy, transmission electron microscopy and Fourier transform spectroscopy were all used to learn more about the cellulose that had been extracted. The extracted cellulose powder comprises a high crystallinity index (68.14 %) and low crystallite size (5.13 nm) found using X-ray diffraction analysis. The smooth and porous surface is observable in scanning electron microscope analysis. The Differential scanning calorimeter curve shows the highest degradation temperature at 218.16 °C. The micro sized particles mostly range between 100 and 120 μm and are found using ImageJ. The surface roughness and permissible skewness of cellulose particles were examined using atomic force microscopy. The density of extracted cellulose is 1.092 g/cm3. The microcrystalline cellulose yield % was notably maximum (40.45 %). This cellulose was introduced in a M30 grade cement concrete as fillers up to 5 % by the weight of cement. The fresh and mechanical properties of the concrete was found to get improved with the addition of cellulose up to 3 %. As a result, the characteristics of cellulose boost its utility within the construction sector.

A comparative study of prescribed thermal analysis of a non-Newtonian fluid between exponential and linear porous surfaces

The present study communicates with the thermal analysis of an incompressible micropolar fluid by considering two different prescribed conditions corresponding to two different surfaces. On the porous surface of two different stretchable sheets, the unsteady flow problem of a micropolar fluid is explored by taking the variable impacts of the magnetic field. For both considered sheets, the prescribed thermal analysis is carried out with the contribution of joule heating, viscous dissipation, and radiation. Two prescribed cases of surface temperature and heat flux are discussed for linear stretched surface. Similarly, prescribed cases of exponential surface temperature and exponential heat flux are investigated for the case of an exponential stretchable surface. An effective technique of bvp4c in MATLAB is utilized to numerically tackle the governing equations of the problem. Both the distributions of temperature and velocity and the field of microrotation are graphically scrutinized relative to different geometries and several pertinent parameters. This study of thermal analysis with prescribed conditions elucidates that for an exponential surface, three distributions of flow phenomenon (temperature, microrotation, velocity) manifest more prominent results in comparison to the stretchable surface with linear velocity.

Synergistic adsorption of real phosphorus-containing domestic wastewater by in-situ growth of MgFe-layered double hydroxides co-doped with dual-functional lignosulfonate and La(OH)3 on wood-derived cellulose aerogel

Recovering and reusing of phosphorus (P) in wastewater is the optimal solution to address mineral shortages and eutrophication. Here, the layered double hydroxides (LDHs) grown on wood-derived aerogels (WAs) were prepared after screening the powdered precursors and named La/MgFe-LDH(LS)@WAs. The intricate pore structure and surface morphology of the WAs formed a fibrous network with ultra-low density, good strength and elasticity, allowing for uniform loading. The sample exhibited excellent adsorption capacity of 139.5 mg P/g at pH 4.0, and over 100.0 mg P/g within a wide pH range (3.0–8.0). Thomas and Yoon-Nelson models could effectively describe the dynamic adsorption process. Microscopic morphology and textural characteristics of the samples were characterized and molecular dynamics (MD) simulations and theoretical calculations based on density functional theory (DFT) were used to study the interaction mechanisms. The coordination bonds and weak interactions between the active component LS and La(OH)3 with phosphates were characterized using interaction region indicator (IRI) and independent gradient model based on Hirshfeld molecular density partitioning (IGMH) methods. The atomic δg index mapped to the molecular structure vividly illustrated the maximum contribution of hydroxyl hydrogen to phosphate deprotonation oxygen in inter-fragment interactions on LS. Combining the formation of Me-O-P bonds characterized by X-ray photoelectron spectroscopy (XPS), the mechanism involves weak interactions (hydrogen bond) and chemical adsorption via ligand exchange. High removal efficiency was demonstrated in real wastewater. A method for waste reuse was also proposed. Plant cultivation experiments showed that La/MgFe-LDH(LS)@WAs could sustain wheat growth with slowly degrade and maintain high phosphate availability. The composite shows potential for water restoration, waste treatment, and value-added conversion in the production of controlled-release fertilizers.

Improving Adsorption Efficiency of Recycled Activated Carbon from Household Water Purifiers through Sonication

Objectives:This study evaluated the potential of recycled activated carbon from household water purifiers as an adsorbent for removing methylene blue. It aimed to achieve resource recycling and dyeing wastewater treatment through the sonication modification of recycled activated carbon.Methods:After sieving recycled activated carbon from water purifiers to a particle size of 75-150μm, the material, in this paper referred to as PCB-S, was processed using sonication to enhance its adsorption capacity. The characteristics of PCB-S were analyzed using SEM, XRD and BET analysis. To evaluate its efficacy, adsorption experiments were carried out varying the following parameters: PCB-S dosage (0.05-0.6gL-1), pH (2.0-10.0), initial concentration of methylene blue (100mgL-1), reaction time (1440 min), and temperature (298 K). The data from these experiments were analyzed using first and second-order kinetic models to understand the reaction kinetics, and the adsorption efficiency was further compared using Langmuir and Freundlich isotherm models. Finally, the thermodynamic properties of the adsorption process between PCB-S and methylene blue were studied to determine its endothermic nature and spontaneity.Results and Discussion:The analysis of the surface characteristics of PCB and PCB-S revealed that sonication significantly altered the pore structure of the activated carbon, leading to increases in both the specific surface area and pore volume. XRD analysis, indicated that sonication had no impact on the crystalline or amorphous structure of the activated carbon. PCB-S demonstrated superior porosity and adsorption capabilities compared to PCB. With a dosage of 0.6gL-1, PCB-S was able to remove 65% of methylene blue from the solution. The adsorption kinetics were best described by a pseudo-second-order kinetic model, with the Langmuir adsorption isotherm fitting the data most accurately. The Gibbs free energy (-1.90~-1.32kJ mol-1) and enthalpy change (7.44 kJ mol-1) confirmed that the adsorption reaction was endothermic.Conclusion:This study confirmed that recycled activated carbon from water purifiers exhibits excellent effectiveness as a dye removal adsorbent when subjected to sonication treatment. Therefore, the possibility of utilizing recycled household water purifier filters as adsorbents is expected to contribute to reducing waste disposal costs by promoting resource recycling.

Functional properties and continuous adsorption process of Arenga pinnata shell and its porous biochars for aqueous methylene blue removal

Arenga pinnata shell, an agricultural-processing residue, was used as an alternative precursor for synthesizing Arenga pinnata shell particles (ASP), Arenga pinnata shell biochar (ASB), and Arenga pinnata shell activated biochar (ASAB) for methylene blue (MB) adsorption. Optimized adsorbent was observed for ASAB fabricated via an impregnation ratio of KOH to ASP of 0.5:1 (w/w) at 700 °C for 30 min of activation time under N2 pyrolysis, with a surface area, pore volume, and average pore diameter of 967 m2/g, 0.572 cm3/g, and 2.47 nm, respectively. The adsorbent also possesses the largest carbon constituent (90.4 %), negative surface charge (−36.4 mV), and abundant oxygen-containing functional groups. Dynamic MB adsorption properties on the adsorbents from the aqueous environment under continuous mode at 25 °C were determined using the Thomas and Yoon-Nelson models. Although the ASP and ASB presented comparatively favorable adsorption properties, the optimum adsorption performance was observed for the ASAB. Its superior functional features contributed to the largest adsorption capacity of 203.86 mg/g. The elemental composition analysis indicated the presence of sulfur on the ASAB surface, which supported the findings. This research demonstrates the utility of Arenga pinnata shell as an eco-friendly precursor for high-performance adsorbent fabrication with excellent MB adsorption properties.

Effect of binder phases on the microstructure and sliding wear properties of HVOF-sprayed WC-based coatings

This study aimed to evaluate the microstructure and wear properties of WC-10Co-4Cr, WC-12Co, and WC-17Co coatings on TC4 titanium alloy. The coatings were deposited using high velocity oxygen-fuel (HVOF) technique. To analyze the influence of binder phases, the coatings were thoroughly examined using scanning electron microscopy, X-ray diffractometer, microhardness tester, and friction and wear tester. The analysis of the results reveals that the primary phases in all three coatings consist mainly of WC, with smaller quantities of W2C and amorphous phases present. The WC-10Co-4Cr powder demonstrates a relatively even particle size distribution, high degree of sphericity, and rough porous surface, allowing for efficient heat absorption and uniform heat distribution, resulting in a dense coating. Notably, the WC-10Co-4Cr coating exhibits significantly smaller tungsten carbide grain size compared to the other coatings. Moreover, the microhardness of the WC-10Co-4Cr coating, measured at 1377.8 HV0.05, is significantly higher than that of the WC-12Co and WC-17Co coatings, which measured at 1258.8 HV0.05 and 1182.4 HV0.05, respectively. Additionally, the WC-10Co-4Cr coating demonstrates low friction coefficient and wear volume, indicating excellent wear resistance. Subsequently, a comprehensive analysis was conducted to determine the reasons for the relative enhancement in binder performance.

Establishment of Linear Stability Analysis Method of Hypersonic Boundary Layer Reflecting Porous Surface Effect

Establishment of Linear Stability Analysis Method of Hypersonic Boundary Layer Reflecting Porous Surface Effect

Detection of water pollutants using super-hydrophobic porous silicon-based SERS substrates.

Super hydrophobic porous silicon surface is prepared using a wet chemical synthesis route. Scanning electron microscopic investigation confirms a correlation between pore size and reaction time. SERS substrates are prepared by silver nanoparticle deposition on porous silicon surface. They exhibit excellent characteristics in terms of sensitivity, reproducibility, stability, and uniformity. They could detect rhodamine 6G in femtomolar range with SERS enhancement factor of ~ 6.1 × 1012, which is best ever reported for these substrates. Molecule-specific sensing of water pollutants such as methylene blue, glyphosate, andchlorpyrifos, is demonstrated for concentrations well below their permissible limits along with excellent enhancement factors. Porous silicon substrate functionalized with Ag nanoparticles demonstrates to be a promising candidate for low-cost, long-life, reliable sensors for environmental conservation applications.

Exploring the circular prospects of cashew nutshells and avocado seeds as potential adsorbents for onboard natural gas storage

Natural gas (NG), known for its eco-friendly energy attributes, faces challenges such as low volumetric density, leakage susceptibility, and explosion risks during storage and transport. To narrow this gap, this study reports on the potential of bio-based adsorbents from cashew nut shells (CNS) and avocado seeds (AVS) as an alternative approach for the onboard storage of NG. CNS and AVS were characterized to determine moisture content, volatile matter content, ash content, and fixed carbon content. Additionally, the study determined the optimal loading of activating agents to produce activated carbons (ACs). ACs were produced through a dual process involving simultaneous chemical activation and carbonization. In the chemical activation phase, a sample of either cashew nut shells (CNS) or avocado seeds (AVS) was impregnated with phosphoric acid at various ratios. Subsequently, the properties of the ACs, including surface area, pore volume, and X-ray diffraction (XRD), were evaluated. The NG adsorption capacity of the ACs was assessed, and Freundlich and Langmuir isotherm adsorption equations were derived to elucidate the NG adsorption behavior on the ACs. The results revealed that the proximate analysis of CNS and AVS showed low moisture content (6.48% and 8.91%), high volatile matter (80.21% and 73.09%), low ash content (1.48% and 4.71%), and high fixed carbon (13.65% and 15.59%), indicating suitability for AC formulations. During synthesis, adding phosphoric acid to AVS or CNS in a 1:1 ratio resulted in significantly larger surface areas and pore volumes in the produced ACs. X-ray diffraction analysis of the ACs produced from CNS or AVS with phosphoric acid added at a 1:1 ratio indicated a broad diffraction background and a predominantly amorphous structure. The performance of the ACs in the adsorption of NG demonstrated that ACs produced from 1:1 mixtures of CNS with phosphoric acid and AVS with phosphoric acid exhibited higher adsorption capacities, 0.038 g/g and 0.031 g/g, respectively, at a low pressure of 5 bar, showcasing a novelty of this study. Furthermore, the Freundlich equation test yielded a constant R² exceeding 0.9, with positive adsorption intensity and adsorption capacity values, indicating a favorable fit for the model. In contrast, the Langmuir equation test resulted in a constant R² exceeding 0.9, but the adsorption capacity exhibited negative values, leading to inconclusive explanations. These findings affirm that bio-wastes can be an effective source of adsorbents for onboard natural gas storage , suggesting a means to reduce the take-dispose model and promote a circular economy in the energy sector.