Search Results (216)

Ecotribology focuses on both saving energy resources and reducing environmental pollution. Considering environmental concerns, water-based nanolubricants have gained significant attention over conventional oil-based ones. Non-ecotoxic and highly environmentally friendly nanoadditives were chosen for nanolubricant synthesis, especially considering their use at elevated temperatures. In this study, hexagonal boron nitride nanosheets (hBNNSs) and titanium dioxide nanoparticles (TiO₂ NPs) were used to prepare water-based lubricants with glycerol and surfactant sodium dodecyl benzene sulfonate (SDBS) in water under ultrasonication. An Rtec ball-on-disk tribometer was used to investigate the tribological performance of the synthesised water-based lubricants containing different nano-hBN/TiO₂ concentrations, with dry and water conditions used as benchmarks. The results indicated that the water-based nanolubricant containing 0.5 wt% hBN and 0.5 wt% TiO₂ exhibited the best tribological performance at both ambient (25 °C) and elevated (500 °C) temperatures. This optimal concentration leads to a reduction in the coefficient of friction (COF) by 72.9% and 37.5%, wear of disk by 62.5% and 49%, and wear of ball by 74% and 69% at ambient and elevated temperatures, respectively, compared to that of distilled water. Lubrication mechanisms were attributed to the rolling, mending, tribofilm, solid layer formation, and synergistic effects of hBNNSs and TiO₂ NPs. Full article

The purpose of this paper is to use an informatics-based analysis to develop a rational design approach to the accelerated screening of nano-composite materials. Using existing nano-composite data, we develop a quantitative structure–activity relationship (QSAR) as a function of polymer matrix chemistry and nano-additive volume, with the property predicted being electrical conductivity. The development of a QSAR for the electrical conductivity of nano-composites presents challenges in representing the polymer matrix chemistry and backbone structure, the additive content, and the interactions between the components while capturing the non-linearity of electrical conductivity with changing nano-additive volume. An important aspect of this work is designing chemistries with small training data sizes, as the uncertainty in modeling is high, and potentially the representated physics may be minimal. In this work, we explore two important components of this aspect. First, an assessment via Uniform Manifold Approximation and Projection (UMAP) is used to assess the variability provided by new data points and how much information is contributed by data, which is significantly more important than the actual data size (i.e., how much new information is provided by each data point?). The second component involves assessing multiple training/testing splits to ensure that any results are not due to a specific case but rather that the results are statistically meaningful. This work will accelerate the rational design of polymer nano-composites by fully considering the large array of possible variables while providing a high-speed screening of polymer chemistries. Full article

In this paper, MXene nanosheets were used as nano additives for the preparation of MXene-modified polyvinyl chloride (PVC) mixed max membranes (MMMs) for the rejection of lead (Pb²⁺) ions from wastewater. MXene nanosheets were introduced into the PVC matrix to enhance membrane performance, hydrophilicity, contact angle, porosity, and resistance to fouling. Modeling and optimization techniques were used to examine the effects of important operational and fabrication parameters, such as pH, contaminant concentration, nanoadditive (MXene) content, and operating pressure. Predictive models were developed using experimental data to assess the membranes’ performance in terms of flux and Pb²⁺ rejection. The ideal circumstances that struck a balance between long-term operating stability and high removal efficiency were found through multi-variable optimization. The optimized conditions for the best rejection of Pb²⁺ ions and the most stable permeability over time among the membranes that were manufactured were the initial metal ions concentration (2 mg/L), pH (7.89), pressure (2.99 bar), and MXene mass (0.3 g). The possibility of combining MXene nanoparticles with methodical optimization techniques to create efficient membranes for the removal of heavy metals in wastewater treatment applications is highlighted by this work. Full article

Water scarcity poses a formidable challenge around the world, especially in arid regions where limited availability of freshwater resources threatens both human well-being and ecosystem sustainability. Membrane-based desalination technologies offer a viable solution to address this issue by providing access to clean water. This work ultimately aims to develop a novel permselective polymeric membrane material to be employed in an electrochemical desalination system. This part of the study addresses the optimization, preparation, and characterization of a polyvinylidene difluoride (PVDF) polymeric membrane using the electrospinning technique. The membranes produced in this work were fabricated under specific operational, environmental, and material parameters. Five different additives and nano-additives, i.e., graphene oxide (GO), carbon nanotubes (CNTs), zinc oxide (ZnO), activated carbon (AC), and a zeolitic imidazolate metal–organic framework (ZIF-8), were used to modify the functionality and selectivity of the prepared PVDF membranes. Each membrane was synthesized at two different levels of additive composition, i.e., 0.18 wt.% and 0.45 wt.% of the entire PVDF polymeric solution. The physiochemical properties of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential, contact angle, conductivity, porosity, and pore size distribution. Based on findings of this study, PVDF/GO membrane exhibited superior results, with an electrical conductivity of 5.611 mS/cm, an average pore size of 2.086 µm, and a surface charge of −38.33 mV. Full article

Efficient lubrication lowers friction, wear, and energy losses in automotive drivetrain components. Advanced lubricants are key to sustainable transportation performance, durability, and efficiency. This study analyzes the tribological performance of Group III base oil with CuO and ZnO nanoadditive mixtures. These additives enhance the performance of Group III base oils, making them highly relevant for automotive lubricant applications. An Optimol SRV5 tribometer performed ball-on-disk sliding contact tests with 100Cr6 steel specimens subjected to a 50 N force and a temperature of 100 °C. The test settings are designed to mimic the boundary and mixed lubrication regimes commonly seen in the automobile industry. During the tests, the effect of nanoparticles on friction was measured. Microscopic wear analysis was performed on the worn specimens. The results demonstrate that adding 0.3 wt% CuO nanoparticles to Group III base oil achieves a 19% reduction in dynamic friction and a 47% decrease in disk wear volume compared to additive-free oil. Notably, a 2:1 CuO-to-ZnO mixture produced synergy, delivering up to a 27% friction reduction and a 54% decrease in disk wear. The results show the synergistic effect of CuO and ZnO in reducing friction and wear on specimens. This study highlights the potential of nanoparticles for lubricant development and automotive applications. Full article

In the field of mechanical motion, friction loss and material wear are common problems. As one of the essential components for enhancing the lubricating performance of gel-like lubricants, nano-additives leverage their unique physical and chemical properties to form an efficient protective film on friction surfaces. This effectively reduces friction resistance and inhibits wear progression, thereby playing a significant role in promoting energy conservation, emissions reduction, and the implementation of green development principles. This study first introduces the physical and chemical preparation processes of gel-like lubricant nanoadditives. It then classifies them (mainly based on metal bases, metal oxides, nanocarbon materials, and other nanoadditives). Then, the performance of gel-like lubricant nano-additives is evaluated (mainly in terms of anti-wear, friction reduction, oxidation resistance, and load carrying capacity), and the surface analysis technology used is described. Finally, we summarize the application scenarios of gel-like lubricant nano-additives, identify the challenges faced, and discuss future prospects. This study provides new insights and directions for the design and synthesis of novel gel-like lubricants with significant lubricating and anti-wear properties in the future. Full article

LiNO₃-NaNO₃-KNO₃-NaNO₂ has a relatively low phase-change temperature, making it suitable for low-temperature heat utilization systems. This study focuses on the performance optimization of the quaternary molten salt to advance its applicability. A series of nanocomposites consisting of nano-SiO₂/MgO and the quaternary salt are prepared. Core thermophysical properties, including phase transition behaviors and thermal transport parameters, are quantified. The incorporation of nano-SiO₂/MgO induces moderate adjustments to the melting point and latent heat yet demonstrates an obvious enhancement in specific heat capacity. Optimal doping at 0.7 wt.% SiO₂ and 0.3 wt.% MgO yields a molten-state specific heat of 1.51 J/(g·K), representing a 6% increase over the undoped base salt (1.42 J/(g·K)). By combining the thermal diffusivity properties of the samples, this study found that the doping of nanoparticles typically induces new structures in molten salts that tend to enhance the specific heat capacity while simultaneously reducing thermal diffusivity. Full article

MgO–C refractory materials were developed by incorporating different ratios of alumina/titania nano-additives which were synthesized chemically. Their physical and mechanical properties, oxidation resistance, slag wettability, bulk density, apparent porosity, cold crushing strength, oxidation index, and closed porosity were tested, evaluated, and compared using conventional techniques as well as X-ray micro-computed tomography (µCT). This investigation indicated a slight degradation of physical properties and mechanical strengthening which was stronger for samples with increased alumina content. Oxidation and corrosion extent were tested both with X-ray tomography and conventional methods. The first method allowed for the calculation of the oxidation index, the detection of closed porosity, and an improved analysis of the internal corrosion, avoiding the sectioning of the materials. This result confirms the supremacy of the first technique. On the contrary, although conventional methods such as the Archimedes procedure cannot detect close porosity, they provide more accurate measurements of the physical properties of refractories. This study shows that conventional methods exhibit superiority in investigations of the pore structures of refractories for pore sizes in the range 1–2 μm, while the use of the μCT system is limited for pore sizes equal to or larger than 20 μm. Full article

With the continuous improvement in technology, the construction industry is constantly advancing. Traditional concrete can no longer meet modern market demands, making research on new types of concrete imperative. This study reviews the application of common nanomaterials in concrete and their impact on concrete performance. It provides a detailed explanation of the characteristics of three common nanomaterials: nano-silica, nano-calcium carbonate, and carbon nanotubes. This study analyzes how these materials improve the microstructure, accelerate hydration reactions, and enhance interfacial transition zones, thereby enhancing the mechanical properties, durability, and workability of concrete. For conventional engineering projects, nano-calcium carbonate is the preferred choice owing to its low cost and its capacity to improve workability and early-age strength. For high-strength and durable structures, nano-silica is selected due to its high specific surface area (ranging from 100 to 800 m²/g) and its superior compactness and impermeability. In the context of intelligent buildings, carbon nanotubes are the most suitable option because of their exceptional thermal conductivity and electrical conductivity (with axial thermal conductivity reaching 2000–6000 W/m*K and electrical conductivity ranging from 10³ to 10⁶ S/cm). However, it should be noted that carbon nanotubes are the most expensive among the three materials. Additionally, this study discusses the issues and challenges currently faced by the application of nanomaterials in concrete and looks ahead to future research directions, aiming to provide a reference for further research and engineering applications of nanomaterials in the field of concrete. Full article

The widespread use of mineral cutting fluids in metalworking poses challenges due to their poor wettability, toxicity, and non-biodegradability. This study explores cactus oil-based nanofluids as sustainable alternatives for metal cutting applications. Samples of cactus oil are prepared in plain form and with 0.025 wt.%, 0.05 wt.%, and 0.1 wt.% activated carbon nanoparticles (ACNPs) from recycled plastic waste. Plain cactus oil exhibited a 34% improvement in wettability over commercial soluble oil, further enhanced by 60% with 0.05 wt.% ACNPs. Cactus oil displayed consistent Newtonian behavior with a high viscosity index (283), outperforming mineral-based cutting fluid in thermal stability. The addition of ACNPs enhanced the dynamic viscosity by 108–130% across the temperature range of 40–100 °C. The presence of nano-additives reduced the friction coefficient in the boundary lubrication zone by a maximum reduction of 32% for CO2 compared to plain cactus oil. The physical and rheological results translated directly to the observed improvements in surface finish and tool wear during machining operations on H13 steel. Cactus oil with 0.05 wt.% ACNP outperformed conventional fluids, reducing surface roughness by 35% and flank wear by 57% compared to dry. This work establishes cactus oil-based nanofluids as a sustainable alternative, combining recycled waste-derived additives and non-edible feedstock for greener manufacturing. Full article

The main aim of this research was to synthesize the new geopolymer composite and test its antibacterial properties. The new composites are based on a geopolymer matrix, with the addition of carbon fiber, nano-silica and antibacterial nanopowder. The first stage of this research was the synthesis of geopolymer composites containing variable proportions of nano-additives and, as a reference material, cement. The next step was bacterial cultivation. Two different bacterial strains were selected, Gram-positive and Gram-negative (Escherichia coli and Staphylococcus aureus). In this stage, the agar microbiological medium is used for the evaluation of bacterial growth inhibition by cement and geopolymers. In the final stage, the growth of the colony was observed and the pH measurements were taken. The final assessment of efficiency was made by using optical microscopy and a colony counter based on the Petri dish. The test performed showed that the main mineralogical components are quartz, 55.0%, and mullite, with 42.1% of crystalline ingredients. EDS analysis shows that the main oxide component is SiO₂, about 50.9%. The obtained results connected with bacteria growth show the growth of both types of bacteria on materials; however, after several days, the growth was inhibited. An assessment of microorganism growth inhibition by cement and geopolymers shows the better efficiency of geopolymer composites in this area for both types of colonies (Gram-positive and Gram-negative). The new element in this research was to plan the research from the point of view of its application in the water environment. The provided research can be useful for the inhibition of biofouling phenomena on marine and inland water infrastructure. Full article

Although polyethylene is widely used in electrical insulation, it does not possess dielectric properties. It is therefore desirable to develop insulation materials with excellent dielectric properties. In this study, low-density polyethylene (LDPE) was used as a matrix resin, while MgO, wollastonite, and montmorillonite (MMT) were employed as inorganic nano-additives. Three composites were prepared using the boiling–melt blending approach. Power frequency breakdown tests were performed on the original LDPE and on the prepared nanoparticle/LDPE composites. Upon combination with the Weibull distribution, the breakdown test results revealed that the addition of these nano-additive particles to the LDPE matrix increased the breakdown field strength of the material. The highest breakdown field strength for the nano-MgO/LDPE composite was obtained using a MgO loading of 0.5%. Notably, the obtained value was 1.8% higher than that of the pure LDPE. In addition, the highest breakdown field strength for the nano-wollastonite/LDPE composite was obtained using a wollastonite loading of 1% (7.48% higher than that of pure LDPE). Similarly, the highest breakdown field strength of the nano-MMT/LDPE composite was obtained using an MMT loading of 3%, giving a value that was 6.67% higher than that of the pure LDPE. Full article

This study investigates the performance of biobased and nano-additive lubricants for the sustainable machining of Al6082 alloy. The experiments were conducted in five different cutting environments: dry cutting, olive oil-based minimum quantity lubrication (MQL), sunflower oil-based MQL, olive oil-based MQL with nano-SiO₂ additives, and sunflower oil-based MQL with nano-SiO₂ additives. The machining performance was evaluated in terms of key parameters such as surface roughness, cutting forces, tool wear, cutting temperature, and chip morphology. The results show that nano-additive lubricants reduce friction, reduce tool wear, and reduce cutting forces, thus providing lower surface roughness. The nano-SiO₂-additive olive oil-based MQL method showed the optimum performance by providing the lowest cutting force and temperature values. It was also determined that nano-additive lubricants contributed to more regular chip formation. The study reveals that the use of biobased nano-lubricants in sustainable machining processes offers environmental and economic advantages. In the future, it is recommended to examine different types and concentrations of nanoparticles, conduct long-term tool wear analyses, and evaluate the effects on other machining methods. Full article

The amalgamation of nanomaterials with bio-lubricants presents a promising approach to enhance the performance and efficiency of mechanical systems. To address the overuse of conventional lubricants, a viable strategy involves harnessing the potential of naturally available lubricants to operate effectively under extreme operating conditions, such as high loads and high-temperature and high-friction environments. The incorporation of nanomaterials, with their high surface area, extended thermal conductivity, and enhanced load-carrying capacity, offers an effective means of producing alternatives to traditional lubricants. This study aimed to investigate the impact of incorporating nanomaterials in small percentages of 2%, 4%, and 6% into bio-lubricants to reduce friction and improve their tribological performance. A systematic analysis of the effects of nanomaterials on lubrication parameters, such as shear rate, shear stress, torque, and viscosity, was performed. The experimental results indicate that the incorporation of nanomaterials into bio-lubricants aligns their parameters closely with those of commercial lubricants, suggesting their potential as a viable alternative in the lubricant industry. Full article

The development of green lubrication requires nano-lubricants to possess more environmentally friendly fabrication modes and materials with superior tribological properties. This study investigates the tribological properties of nano-biochar in PAO6 base oil and in combination with different additives. The effect of adsorption on friction reduction and anti-wear performance is demonstrated by replacing the friction sub-materials in the four-ball friction test. Based on the comparison of wear region characterization, the incorporation of nano-biochar improves the friction reduction performance of detergent and dispersant base oils with a reduction in coefficient of friction (COF) by 16.7% and 19.0%, respectively, and produces a synergistic effect on the anti-wear performance. When nano-biochar is compounded with anti-wear agents and friction reducer, there is a synergistic effect on friction reduction performance, and COF decreases by 9.4% and 4.5% compared with anti-wear agents and friction reducer base oils, respectively. A method to analyze the friction reduction and anti-wear mechanism of nano-additives in complex lubrication system is proposed, which reveals in depth the interaction law and synergistic lubrication mechanism between NBC and additives in the friction process. Full article