Penetration Of Solution Research Articles

Research on the Durability of Composite Epoxy Resin Modified Repair Mortars Based on Water-Oil Gradient Phase Change: From Macroscopic to Nanoscopic Scales

With the rapid pace of urbanization, global demand for concrete is increasing, shifting focus from construction to repair and maintenance. Traditional cement-based repair materials generally suffer from brittleness and poor durability, failing to meet the growing demand for durable repair solutions. We developed a water-oil gradient composite epoxy resin (CEP) modified cement-based repair mortar (MCEP) using self-synthesized water-based epoxy resin (WEP) and oil-based epoxy resin (EP). Durability tests showed that CEP-modified cement mortar exhibited improved resistance to solution penetration, shrinkage, acid corrosion, and freeze-thaw cycles, with increased CEP content positively affecting mortar durability. Notably, the addition of CEP not only enhanced the interface bonding strength between MCEP and old concrete but also maintained good bonding stability under moisture erosion. X-CT and SEM microstructural tests revealed that CEP is evenly distributed in the cement paste, forming a cement-polymer interpenetrating network structure, which improves crack resistance and reduces solution penetration in MCEP. Molecular dynamics simulations explored the adsorption of CEP on calcium aluminate hydrate (AFt), a key cement hydration product, and the moisture transport mechanisms in AFt and CEP-modified AFt nanopores. Results indicated that CEP molecules adsorb onto AFt via ionic and hydrogen bonds, demonstrating good stability. During moisture penetration, CEP reduced water transport efficiency in the nanopores. CEP modification improved the crack resistance and durability of cement repair mortars, providing valuable insights into molecular-scale enhancements in water permeability resistance. This study aims to contribute to the design and practical application of water-oil gradient epoxy resins and other polymer-modified cement-based repair materials.

Study of the effect of forced precipitation of working fluid on a vineyard sprayer for weed control

BACKGROUND: A distinctive feature of the sprayer presented is the possibility of more efficient penetration of the working solution into the middle and lower tiers of weeds, as well as on the lower (abaxial) side of the leaf. This is ensured by the use of an air-liquid jet, which significantly increases the effectiveness of the applied chemical method of weed control. AIM: Analysis of the effect of air jets on the deposition of chemicals on the surface of leaves of weeds. The penetration of the drug into the middle and lower tiers of plants, as well as deposition on the adaxial and abaxial sides of the leaves, is taken into account. METHODS: To combat unwanted vegetation, a special device was applied, which was used in field research both with and without air support. With the help of the developed method, spraying was carried out on indicator cards fixed on the upper, middle and lower tiers of the plant RESULTS: For the first time, an innovative technology based on the use of a flexible air distribution sleeve as part of a herbicide sprayer was proposed to combat weeds in vineyards. This sleeve ensures the precise supply of airflow from the fan to the working fluid spraying area. The result of such an air-liquid flow is improved efficiency and monodispersity of herbicide droplets, which, in turn, ensures uniform coverage of the lower tiers and the abaxial surface of the leaves of weeds. This innovative solution opens up new prospects in the fight against unwanted vegetation in the vineyards. CONCLUSION: The practical value of the proposed weed control technology lies is increasing the quality of the technological operation due to the forced precipitation of the working solution.

Experimental and molecular dynamics simulation studies on the effect of composite surfactants on the wettability of anthracite coal

In order to improve the wettability of coal bed water injection, the effects of several composite surfactants on the wettability of anthracite coal were investigated. Firstly, the wettability of different composite surfactants on anthracite was analysed by macroscopic experiments (surface tension and settling time) to determine the optimal concentration and optimal ratio of composite surfactants. Secondly, the effects of adsorption of different composite surfactants on the physicochemical properties of the coal dust surface were investigated by mesoscopic experiments (scanning electron microscopy, energy spectrometer analysis, infrared spectroscopy, X-ray electron spectroscopy and zeta potential), and the results showed that the content of hydrophilic functional groups (Si-O-Si, C-O-C, C-O and CO) on the surface of anthracite coal after treatment with the composite surfactant increased significantly, and the surface potential value decreased significantly in absolute value, agglomerated large coal particles would be formed on the coal surface, and the cracks between coal particles were favourable for the penetration of aqueous solution. Finally, the synergistic mechanism of different composite surfactants was analysed from the perspective of microscopic molecular simulation. The results showed that the composite surfactants enhanced the interaction energy of the coal/composite surfactant/water system, improved the relative concentration distribution of the system, and increased the diffusion coefficient of water molecules. The results of the study can provide valuable guidance for the development of new composite surfactants with wetting effect, which has important application value for mine dust control.

Improving the impermeability of cement/epoxy coating interface by g-C3N5: A molecular dynamics study

The accumulation of chloride that penetrates through the concrete cover from the ambient environment is the primary factor contributing to the interfacial degradation between concrete and epoxy-coated steel rebar. In this study, a nitrogen-rich carbon nitride (g-C3N5) modified epoxy (EP) coating is proposed to enhance the impermeability of the concrete/epoxy interface. The local structure, dynamic characteristics, and impermeability mechanism of g-C3N5 inserted into the interface of concrete/epoxy coating during the penetration of NaCl solution are studied using the molecular dynamics method. It is found that the insertion of g-C3N5 at the concrete/epoxy interface effectively slows down the penetration of NaCl solution. The g-C3N5 nanosheets block the C-S-H channel, and the water molecules form hydrogen bonds with the nitrogen and oxygen-containing groups in the g-C3N5 grafted with oxygen-containing functional groups (g-C3N5-COOH), significantly inhibiting the movement of water molecules. The oxygen-containing functional groups on g-C3N5-COOH form hydrogen bonds with the non-bridging oxygen on the surface of C-S-H and the oxygen in EP, respectively. This enhances the interaction of the C-S-H/epoxy interface and reduces the degree of interfacial peeling. The impermeability mechanism of the C-S-H/epoxy interface and the capture of corrosive particles can offer molecular insights into the interface design of cement/organic coatings.

EFFICIENT COPPER EXTRACTION FROM CHALCOPYRITE USING THE «GLYCOLIC ACID – ETHYLENE GLYCOL – SODIUM LAURYL SULFATE» SYSTEM

This research explores a sustainable and efficient method for extracting copper from chalcopyrite, utilizing an innovative leaching system composed of glycolic acid, ethylene glycol, and sodium lauryl sulfate (SLS). The optimal conditions identified were 1,0 M glycolic acid, 20% (v/v) ethylene glycol, 0,8% (w/v) SLS, and a temperature of 75°C, achieving up to 85% copper recovery. Glycolic acid plays a dual role, promoting the breakdown of the chalcopyrite structure and stabilizing copper ions in the solution. SLS improves the leaching efficiency by disrupting the passivating sulfur layer, allowing for better solution penetration. Additionally, ethylene glycol prevents the precipitation of sulfur, further enhancing the process. The combination of these components creates a synergistic effect that improves copper recovery while minimizing environmental impact. The findings suggest that this leaching system could serve as a sustainable and efficient alternative to the traditional pyrometallurgical methods, offering potential applications in industrial copper recovery processes.

Impact of different activation procedures on sodium hypochlorite penetration into dentinal tubules after endodontic retreatment via confocal laser scanning microscopy

BackgroundInfected dentinal tubules are a possible source of bacteria that are responsible for the failure of root canal treatment. Therefore, disinfection of dentinal tubules by increasing the penetration of the irrigation solution is important for success in retreatment cases. This study utilized confocal laser scanning microscopy (CLSM) to assess and compare the impact of XPR, ultrasonic irrigation (UI) and sonic activation (SA) on NaOCl penetration into dentinal tubules following endodontic retreatment.MethodsA total of forty mandibular premolars were enrolled in this investigation. Following root canal preparation up to ProTaper X3 file (30/0.07), root canals were obturated with gutta-percha and bioceramic root canal sealer with single cone technique. The root canal filling materials were removed using ProTaper nickel-titanium rotary retreatment files until the working length was reached. The retreatment procedure was finalized using the ProTaper Next X4 (40/0.06). The teeth were divided into four groups based on the irrigation activation technique: control (conventional needle irrigation), SA, UI and XPR. During the final irrigation procedure, Rhodamine B dye was introduced to 5% NaOCl for visualization via CLSM. Subsequent to image acquisition, the maximum penetration, penetration percentage, and penetration area were calculated. Data were statistically analyzed using the Kruskal-Wallis, Friedman, and Bonferroni Dunn multiple comparison tests through R software (p < 0.05).ResultsIn the middle third, UI yielded a significantly higher penetration percentage than the control group (p < 0.05). The UI and XPR groups showed increased penetration percentages in the coronal and middle thirds compared with the apical third (P < 0.05). Maximum penetration was notably reduced in the apical third than in comparison with the coronal and middle thirds in all groups (p < 0.05). In the control, SA and XP groups, the penetration area was ranked in descending order as coronal, middle and apical (p < 0.05). Conversely, in the ultrasonic group, the penetration area was significantly lower in the apical third than in the middle and coronal thirds (p < 0.05).ConclusionsUI enhanced the penetration percentage in the middle third of the root compared with that in the control group. XPR and SA showed no significant effect on NaOCl penetration following retreatment.

High-density, reversible of hydrogen-bonding and Fe3+ ion bridging enable the fabrication of multifunctional PVA-based composites

The development of continuously degradable and recyclable polymeric composites with superb mechanical properties, which can extend the service life of materials and reduce the environmental impact, will make a significant contribution to global sustainability. In this study, poly(vinyl alcohol) (PVA)-based composites (D-PVA-Fe-TA) with degradability, recyclability and excellent mechanical properties are prepared by complexation of 3,4-dihydroxybenzaldehyde-grafted PVA (D-PVA), tannin (TA) and Fe3+ ions in dimethyl sulfoxide (DMSO), and then dialysis in deionized water and glycerol (Gly). The two-step dialysis process, playing a crucial role in reducing the free water of D-PVA-Fe-TA composites, enhances the formation of reversible of hydrogen-bonding and the reinforcement of self-assembled Fe3+-chelation between TA and D-PVA, and facilitates the fabrication of PVA-based composites with a breaking strength of ≈ 18.7 MPa, an elongation at break of ∼ 812 % and a toughness of ≈ 86.81 MJ/m3; Meanwhile, the resulting homogeneous and dense structure of D-PVA-Fe-TA composites hinders the penetration of Gly solution, thereby enhancing the bonding strength and environmental adaptability of D-PVA-TA-Fe composites within the temperature range of −20℃ to 60℃. Furthermore, the as-prepared D-PVA-TA-Fe composites exhibit recyclability for multiple cycles. When placed under soil culture medium, the resulting composites can be degraded without the need for manual interference. This study presents a novel strategy for the fabrication of materials possessing excellent mechanical strength, environmental adaptability, recyclability and degradation, which have great potential for taking the place of conversional composites in specific conditions.

Minimizing liquid/solid interfacial energy boosts Fe−N doping inside hollow carbon sphere for oxygen reduction in membrane-less direct formate fuel cell

Porous hollow carbon sphere (HCS) is an attractive catalyst support for oxygen reduction reaction (ORR) due to its large specific surface area for active site anchoring, porous and hollow structure for active site exposure and mass transfer. However, due to the high transfer resistance for exogenous heteroatoms into HCS, most of active sites are usually loaded on the outer surface of HCS, leading to the decrease of active site density and the aggregation of heteroatomic particles. In this work, we proposed that accompanied with the decrease of liquid/solid interfacial energy by changing solvent composition during impregnation, penetration of exogenous heteroatoms-containing solution was facilitated in HCS, resulting in increased density of uniformly-dispersed Fe−Nx active site by 58 %. Taking advantage of high-content and well-dispersed active site, structure-derived porosity for ion transfer and active site exposure, this HCS-derived catalyst (Fe-HCS@C2H5OH) exhibited positive onset and half-wave potentials of 0.953 V and 0.901 V (vs. RHE), as well as high power density of 20.17 ± 0.31 mW cm−2 when applied in membrane-less direct formate fuel cell cathode, surpassing those of commercial Pt/C and the state-of-the-art carbonaceous catalysts. This strategy of interfacial energy control provides a new stepping-stone for the synthesis of high-performance electrocatalysts.

Corrosion resistance of FeCrMnxAlCu high-entropy alloys in 0.5M H2SO4 solution

In this study, FeCrMnxAlCu high-entropy alloys with varying Mn contents (x = 2.0, 1.5, 1.0, 0.5, and 0) were prepared using a vacuum arc melting furnace. The phase structure and microstructure of the alloys before and after corrosion were characterized via X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion resistance of the alloys in a 0.5 M H2SO4 solution was comprehensively evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy, immersion tests, white light interferometry, and X-ray photoelectron spectroscopy. Microstructural characterization results revealed that the FeCrMnxAlCu high-entropy alloys exhibited mixed FCC and BCC phase structures and featured typical dendritic and interdendritic regions. Corrosion tests indicated that as the Mn content decreased, the corrosion resistance of the high-entropy alloys improved, and the corrosion type transitioned from dendritic to interdendritic. Among these alloys, the FeCrAlCu high-entropy alloy exhibited the highest corrosion resistance, with the highest positive corrosion potential (Ecorr = −0.11 V), the lowest corrosion current density (Icorr = 1.02 × 10−5 A∙cm2), minimal corrosion depth, and the lowest corrosion rate (0.1592 mm/y). After corrosion, a composite oxide protective film was formed on the alloy surface, effectively hindering further penetration of the H2SO4 solution and exhibiting excellent corrosion resistance.

Design and Synthesis of a Robust and Multifunctional Superhydrophobic Coating with a Three-Dimensional Network Structure on a Paper-Based Material.

A fundamental challenge in artificial superhydrophobic papers is their poor resistance to mechanical abrasion, which limits their practical application in different fields. Herein, a robust and multifunctional superhydrophobic paper is successfully fabricated via a facile spraying method by combining silver nanowires and fluorinated titania nanoparticles through a common paper sizing agent (alkyl ketene dimer) onto paper. It is shown that the surface of the paper-based material presents a three-dimensional network structure due to the cross-linking of silver nanowires with a high aspect ratio. Further hydrophilic and hydrophobic performance test results show that it exhibits exceptional water repellency, with a desirable static contact angle of 165° and roll-off angle of 6.2°. The superhydrophobic paper showcases excellent mechanical durability and maintains its superhydrophobicity even after enduring 130 linear sandpaper abrasion cycles or high-velocity water jetting impact benefited from interfacial van der Waals and hydrogen bonding. Simultaneously, the robust superhydrophobic surface can effectively prevent the penetration of acid or alkali solutions, as well as UV light, resulting in excellent chemical stability. Additionally, the superhydrophobic paper offers supplementary features such as self-cleaning, electrical conductivity, and antibacterial capability. Further development of this strategy paves a way toward next-generation superhydrophobic paper composed of nanostructures and characterized by multiple (or additional) functionalities.

Application of lactobacillus casei and lactobacillus plantarum to develop dried functional apple and banana.

The goal of this research was to create dried fruits loaded with probiotic microorganisms (Lactobacillus casei and Lactobacillus plantarum). In separate bottles for each probiotic microbe, apple and banana pieces have been submerged into the impermeability solution with gentle shaking. The vacuum pressure was applied. By the conclusion of the incubation time, L. casei and L. plantarum colonies were enumerated (CFU/g). The scanning electron microscope method was applied to confirm the penetration of impregnation solutions into the intercellular spaces of fruit tissue. On day 28, the population of L. plantarum was 5 log CFU/g for apples and 5.5 log CFU/g for bananas. After storage, the number of L. casei in apples was 5 log CFU/g and 5.5 log CFU/g, respectively. L. casei was found on the surface of apple and banana tissue. After one-week, whole phenolic content of probiotic-enriched bananas and apples augmented. After storage, the antioxidant activity of all samples decreased greatly. The sensory qualities of the samples were excellent throughout storage in terms of color, quality, scent, sensitivity, chewiness, and general adequacy. As a result, dried apples and bananas infused with L. plantarum and L. casei might be a novel probiotic meal. RESEARCH HIGHLIGHTS: Dried apples and bananas infused with L. plantarum and L. casei are novel probiotic meal. After one-week, whole phenolic content of probiotic-enriched bananas and apples augmented. The sensory qualities of the samples were excellent throughout storage in terms of color, quality, scent, sensitivity, chewiness, and general adequacy.

A comparative study between aqueous and methanol solutions of barium hydroxide: implications for applying barium protectants in gypsification calcareous relics

Gypsification is a common problem in weathered calcareous relics. In previous studies, the solutions of barium hydroxide in water and methanol were used as protectants for gypsification calcareous relics and showed significant differences in permeability. In this study, the underlying reasons for permeability differences between these two solutions were investigated using optical microscopy, ultraviolet–visible spectrophotometry, X-ray diffractometry, Fourier transform infrared spectroscopy, the phenolphthalein test and physical property characterizations. The results indicated that the permeability differences were primarily caused by the solutions’ reactivity. Specifically, owing to the high reactivity of barium hydroxide in water, it reacted rapidly with atmospheric CO2 and gypsum (the weathering product) to generate barium carbonate, barium sulfate and calcium hydroxide precipitates. These precipitates hindered the penetration of solution into weathered relics. In contrast, barium hydroxide in methanol did not react with atmospheric CO2 or weathered relics, which also kept the solution in a liquid state during the infiltration process. Therefore, the solution of barium hydroxide in methanol exhibited high permeability. Based on the above findings, this study is meaningful for applying barium protectants in the conservation of gypsification calcareous relics.

Hierarchical heterostructures of MXene and mesoporous hollow carbon sphere for improved ion accessibility and rate performance

The development of electrode materials with a hierarchically porous structure and good electrical connection is key to improving the charging-discharging rate and energy density of supercapacitors. However, the restacking issue of two-dimensional nanomaterials, such as MXene, seriously hinders the diffusion of electrolyte ions. Different from the extensively used sacrificing template method, a hierarchical heterostructure of electrically conducting mesoporous hollow carbon spheres (MHCS) and MXene composite electrode is designed and achieved through simple vacuum filtration without further template removing procedures. This direct preparation strategy not only effectively improves the specific surface area of the electrode but also enhances the abundant surface pores and good conductivity of MHCS, improving the penetration of the electrolyte solution and shortening the ion transport path, leading to a pronounced improvement in specific capacitance and rate performance of the electrodes. Additionally, the influence of sheath thickness of MHCSs on ion transfer rate is deeply discussed. The introduction of carbon nanotubes (CNTs) further improves conductivity and stability while maintaining good flexibility. Consequently, the MXene/MHCS/CNT film delivers a high specific capacitance (395F g−1 at 2 mV s−1), outstanding rate performance (70.9 % at 1000 mV s−1), and excellent cycling stability (98.3 % capacity retention after 10,000 cycles). Furthermore, the assembled symmetric supercapacitor provides a maximum energy density of 14.48 Wh kg−1. This work provides a quick and effective approach for constructing high performance 3D MXene architectures for fast ion transfer electrodes.

Different effects of TiB2 particles on corrosion behaviors of in-situ TiB2/7075 composites in active and passive environments

The different effects of TiB2 on intergranular corrosion (IGC) and exfoliation corrosion (EXCO) in TiB2/7075 composites were investigated. Lower particle content accelerated IGC due to the first dissolution of large TiB2/Al interface precipitates, causing TiB2 deposition in corrosion channels. Conversely, higher particle content reduced the maximum IGC depth to 47 % with dense corrosion products inhibiting penetration of corrosive solution. EXCO weight loss increased by 271 % and 388 % with 3.5 wt% and 7 wt% particles, respectively. Micro-galvanic corrosion and recrystallization caused by particles reduced EXCO resistance. The passive IGC environment and active EXCO environment lead to different corrosion resistances of composites.

The effect of different irrigation activation methods on the penetration of the irrigation solution into the dentinal tubules in teeth with calcium hydroxide applied and oval-shaped canals: Confocal laser scanning microscope analysis.

This study aimed to evaluate the efficacy of different irrigation techniques including standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo Finisher (XPF), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photo-acoustic streaming (SWEEPS) systems on the penetration of irrigation solutions into dentinal tubules in teeth with calcium hydroxide (CH) applied and oval-shaped canals by confocal laser scanning microscope (CLSM). Ninety mandibular incisor teeth with oval-shaped canals were included in this study. After the preparation of teeth using Resiproc Blue R25 (VDW, Munich, Germany) canals were filled with a paste based on CH. The teeth were stored in 100% humidity at a temperature of 37°C for 14 days. According to the irrigation activation systems, the teeth were divided into six groups (n = 15); SNI, PUI, EA, XPF, PIPS, and SWEEPS. In each group, 3 irrigation/activation cycles of 20 s of irrigation and 20 s of activation were performed with the relevant activation method. The root canals were filled with fluorescein sodium (Sigma, Alldrich Co., St. Louis, MO, USA) and activated with the relevant activation method for 30 s. Specimens were sectioned horizontally to 1 ± 0.1 mm at 2, 5, and 8 mm from the apex and then examined under the CLSM. Maximum penetration depth, maximum penetration area and penetration percentage were measured by using Image J software. Data were analyzed using a two-way analysis of variance (ANOVA) and posthoc Tukey tests (p = .05). No difference was found between the activation systems in terms of maximum penetration depth and maximum penetration area of irrigation solutions in the apical section (p > .05). The penetration percentage of irrigation solutions was higher in PUI and PIPS compared with EA and XPF at the apical section (p < .05). No difference was found between SNI, PUI, PIPS, and SWEEPS in terms of the penetration percentage of irrigation solutions in all sections (p > .05). The penetration percentage of irrigation solutions was higher in the middle and coronal sections compared to the apical section in EA and XPF (p < .05). Tubule penetration of irrigation solutions in SNI was similar between sections. The Tubule penetration area of irrigation solutions in PUI, EA, XPF, PIPS, and SWEEPS was lower in the apical section than in the middle and coronal sections. RESEARCH HIGHLIGHTS: The tubule penetration depth and area of the irrigation solutions were similar between the activation systems tested in the apical sections. The Tubule penetration area of irrigation solutions in middle and coronal sections was higher in PUI and PIPS than in SNI.

Investigation on the mechanism of self-healing effect of cementitious capillary crystalline waterproofing material on concrete and enhancement of its resistance to chloride erosion

To enhance the compactness of concrete in coastal areas and impede the ingress of chloride solutions into the structures, Cementitious capillary crystalline waterproofing material (CCCW) was internal incorporated into concrete. This study employed one-dimensional chloride immersion diffusion tests and wet-dry cycle tests to emulate the deterioration of concrete under natural conditions due to chloride ions. The optimal dosage of CCCW was determined by conducting chemical titration to measure the chloride ion concentration at various depths within the specimens. Subsequently, the influence of incorporating CCCW on the compressive strength of concrete under chloride conditions was assessed. Finally, employing experimental methods such as MIP, SEM and EDS, the pores within cementitious materials and the formation of internal crystals was examined at a microscopic level. Research indicates that in chloride salt environments, the penetration of salt solutions can trigger the formation of spider silk biomimetic shape crystalline structures within the internal pores of CCCW. thereby enhancing the compactness of concrete to achieve a self-healing effect while preventing the intrusion of chloride salt solutions.

Corrosion behaviors of single-layer and double-layer nickel alloy coatings fabricated by arc spraying and high-velocity oxy-fuel

This study investigates single-layer and double-layer thermally sprayed nickel alloy coatings (bond and top coatings). Ni-5 wt% Al and Ni-20 wt% Cr were used as bond coatings, whereas highly alloyed Ni-based coatings, Hastelloy C276 or Inconel 625 were used as top coatings. Arc spraying (A) and high-velocity oxy-fuel (HVOF) techniques were used to create the coatings on a 304 stainless steel substrate. The samples were studied by performing potentiodynamic polarization tests in a 20 vol% H2SO4 solution at room temperature. The scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and wavelength dispersive X-ray spectroscopy (WDS) techniques were used to investigate the microstructure and chemical composition of the coatings. The arc sprayed coatings are composed of a lamellar microstructure with low porosities, unmelted particles, and high oxides at the intersplats. A uniform and compact coating with minimal oxides and porosity was achieved for all coatings via HVOF technique. In single-layer coatings, arc spray coating surpasses HVOF coating owing to its oxide layers, which impede sulfuric solution penetration and bolster resistance against electrolyte infiltration. Double-layer coatings, comprising a bonding layer and a top coating, using the same thermal spray method have shown to enhance corrosion resistance.

Experimental and kinetic analysis of the fluorocarbon structures and coal particles at the microscale

Understanding the dynamic wetting process between liquid droplets and coal dust particles is crucial. Compared to other substances, coal possesses a more intricate microscale molecular chemical structure, with coal's molecular chemical and physical structural characteristics being the primary microscale factors influencing its wetting properties. To enhance the wetting and permeability performance of coal dust, an analysis of the microstructural influences on the wetting process of coal dust through experiments and simulations with five different structured fluorocarbon solutions: perfluorooctane sulfonate sodium (A1), perfluoroisopropyl acrylate (A2), perfluorooctane sulfonic acid ammonium salt (A3), perfluorooctyl alcohol polyoxyethylene ether (N1), and perfluorohexyl ethanol polyoxyethylene ether (N2), was conducted. A wetting theory model (collision–adsorption–immersion) was proposed based on experiments with different concentrations and types of surface tension, and wetting experiments were conducted based on this theory model. The results indicate that smaller coal particle sizes facilitate solution penetration, with the N2 solution demonstrating the best wetting and permeation effects. Microstructural experimental analysis revealed that N2 has more polar functional group structures than the other four fluorocarbon solutions. To further investigate the forces of different structures on coal particles, a molecular dynamics model was employed, and the simulation results indicated that the interaction forces and the number of hydrogen bonds representing the adsorption capacity in the N2 system were the highest.

Fabrication of high-flux PTFE hollow fiber membranes through nonionic surfactant infiltration coupled with mussel-inspired chemistry coating

Polytetrafluoroethylene (PTFE) hollow fiber membrane holds tremendous potential for the treatment of complex wastewater due to its outstanding chemical and thermal stability. However, its treatment efficiency is often hindered by the low water permeate flux arising from the inherent hydrophobicity of PTFE. Here, we present a gentle and convenient hydrophilic modification method that involves immersion in a nonionic surfactant aqueous solution, followed by dopamine self-polymerization. The nonionic surfactant facilitated the penetration of the dopamine solution into the membrane, where dopamine self-polymerized to form a hydrophilic layer on the surface and inner pores of the membrane. The hydrophilicity-modified PTFE hollow fiber membranes demonstrated an impressive increase in water permeate flux, reaching 10231.4 L m−2 h−1, nearly ten times that of the original membrane. Even after prolonged exposure to a strong acid solution (pH = 1) or an oxidant solution (1000 mg L−1 NaClO) for two weeks, this membrane still maintained its favorable water permeability. Furthermore, the modified PTFE membranes also exhibited remarkable resistance to fouling by humic acid. These results showcased a straightforward method for designing a hydrophilic layer on PTFE hollow fiber membranes, underscoring their significant potential for real wastewater treatment applications.

Determination of operational properties of paint coating materials

Problem. Varnishes are used in all branches of industry and economy. With their help, you can protect metals from the effects of aggressive environment, prevent from the negative effects of corrosion, preserve consumer properties, and give the treated surface an aesthetic look. One of the methods of protecting metal from corrosion is the application of coatings, including paints and varnishes, which form a protective film on the surface of the metal and prevent corrosion processes on the surface. Methodology. The research was conducted on the operational characteristics of enamel-type paint coatings: paint powder UD-1028-07040-T and soil FL-03K. Determination of moisture absorption of the free coating film was carried out using the desiccator method. In order to determine the penetration time of aggressive solutions through the paint coating film, an electrochemical method was used, whose purpose is to determine the change in the electrochemical potential of the object under study during the penetration of aggressive solutions through the paint coating film to the metal. The study of the hardness of paint coatings was carried out by the method of static indentation, respectively, using a microhardness meter. Originality. The research results showed the advantage of the UD-1028-07040-T powder paint coating over the FL-03K soil, which can be explained by such factors as the structure of the paint coating, the porosity of the surface, and the phenomenon of adhesion between the paint and the surface on which it is applied. Practical value. Powder paint UD-1028-07040-T absorbs water much less (up to 2.12%) compared to FL-03K soil (up to 5.14%), this indicates a relatively higher porosity of FL-03K soil; it is confirmed by the results of porosity determination, which was 1 point. When determining the penetration time of aggressive solutions through the paint film, it was found that FL-03K soil quickly passes aggressive solutions through its surface (in 144 hours) compared to powder paint (192 hours). This indicates that the use of powder paint in conditions involving contact with aggressive substances will be more appropriate.