Search Results (145)

Due to low thermal conductivity and high specific strength, nickel-based superalloys are prone to service performance degradation caused by thermal damage during traditional high-efficiency grinding processes. Although the heat pipe grinding wheel with minimum quantity lubrication (HPGW-MQL) technology can reduce the probability of thermal damage to a certain extent, further breakthroughs are still needed. Therefore, this study proposes a new integrated process of ultrasonic vibration-assisted grinding by heat pipe grinding wheel with minimum quantity lubrication (UVAG-HPGW-MQL), aiming to balance the requirements of green grinding and the optimization of grinding performance for nickel-based superalloys. However, the mechanism of action of ultrasonic vibration on the cooling and lubrication performance of the proposed process remains unclear. Given that, comparative experiments between UVAG-HPGW-MQL and HPGW-MQL were conducted, focusing on exploring the influence of ultrasonic vibration on their cooling and lubrication performance. The experimental results, obtained when the grinding speed, workpiece feed rate, and grinding depth were set at 15–35 m/s, 40–120 mm/min, and 0.05–0.25 mm, respectively, indicate that, compared with HPGW-MQL, ultrasonic vibration causes periodic “contact-separation” between grains and workpiece. This dynamic process shortens the contact length between grains and workpiece, leading to maximum reductions of 43.85%, 22.15%, 34.16%, and 30.77% in grinding force, grinding force ratio, grinding temperature, and specific grinding energy, respectively. On the other hand, the ultrasonic cavitation effect causes atomization of the lubricating oil film adsorbed on the workpiece surface, leading to a decrease in lubrication performance and resulting in a maximum increase of 27.27% in the friction coefficient. This study provides new theoretical support and technical approaches for the green grinding of nickel-based superalloys. Full article

The increasing volume of produced water (PW) generated by oil extraction activities has intensified the need for environmentally sustainable strategies that enable its reuse and valorization. Biotechnological approaches, particularly those involving the microbial production of value-added compounds, offer a promising route for transforming PW from an industrial waste into a useful resource. In this context, bacterial exopolysaccharides (EPS) have gained attention due to their diverse functional properties and applicability in bioremediation, bioprocessing and petroleum-related operations. This study evaluated the potential of Lelliottia amnigena to synthesize EPS using oilfield PW as a component of the culture medium in stirred-tank bioreactors. Three conditions were assessed: a control using distilled water (dW), PW diluted to 25% (PW25%) and dialyzed PW (DPW). Batch experiments were conducted for 24 h, during which biomass growth, EPS accumulation and dissolved oxygen dynamics were monitored. Post-cultivation analyses included elemental and monosaccharide composition, scanning electron microscopy and rheological characterization of purified EPS solutions. EPS production varied among treatments, with dW and DPW yielding approximately 9.6 g L⁻¹, while PW25% achieved the highest productivity (17.55 g L⁻¹). The EPS samples contained fucose, glucose and mannose, with compositional differences reflecting the influence of PW-derived minerals. Despite reduced apparent viscosity under PW25% and DPW conditions, the EPS exhibited physicochemical properties suitable for biotechnological applications, including potential use in fucose recovery, drilling fluids and lubrication systems in the petroleum sector. The EPS also demonstrated substantial adsorption capacity, incorporating salts from PW and contributing to contaminant removal. This study demonstrates that PW can serve both as a substrate and as a source of functional inorganic constituents for microbial EPS synthesis, supporting an integrated approach to PW valorization. These findings reinforce the potential of EPS-based bioprocesses as sustainable green technologies that simultaneously promote waste mitigation and the production of high-value industrial bioproducts. Full article

The stability of nanolubricants is critical for ensuring effective performance under extreme pressure (EP) conditions, where severe boundary lubrication governs friction and wear behaviour. This study examines palm kernel oil (PKO)-based nanolubricants enhanced with carbon graphene (CG), hexagonal boron nitride (hBN), and molybdenum disulfide (MoS₂), with and without oleic acid (OA) as a surfactant. OA incorporation improved CG dispersion stability, reducing agglomerate size by 30.4% (17.61 μm to 12.23 μm) and increasing the viscosity index from ~176 to 188, compared to 152 for the commercial hydrogen engine oil baseline. Under EP conditions, PKO + CG + OA achieved a 51.7% reduction in the coefficient of friction (0.58 to 0.28) and 18.2% improvement in weld load resistance, while wear scar diameter decreased by 13.4%. Surface and elemental analyses indicated the formation of a composite tribofilm containing oxide species, graphene platelets, and carboxylate-derived compounds from OA, consistent with iron–oleate-like chemistry that enhances load-carrying capacity and wear protection. These findings demonstrate the potential of OA-assisted PKO nanolubricants as sustainable, high-performance formulations for extreme pressure boundary lubrication, contributing to the advancement of green tribology. Full article

Improving ship energy efficiency has become a critical priority for reducing fuel consumption and meeting international decarbonization targets. In this study, eight major groups of energy efficiency improvement systems—including wind and solar energy technologies, hull and propeller modifications, air lubrication, green propulsion options, waste heat recovery, and engine power limitation—were evaluated against seven critical success factors. A hybrid neutrosophic fuzzy multi-criteria decision-making (MCDM) framework was employed to capture expert uncertainty and prioritize alternatives. Neutrosophic fuzzy sets were adopted because they more comprehensively represent uncertainty—simultaneously modeling truth, indeterminacy, and falsity, providing superior capability to address expert ambiguity compared with classical fuzzy, intuitionistic fuzzy, gray, or other uncertainty-handling frameworks. Trapezoidal Neutrosophic Fuzzy Analytic Hierarchy Process (AHP) (TNF-AHP) was first applied to determine the relative importance of the criteria, highlighting fuel savings and cost-effectiveness as dominant factors with 38% weight. Subsequently, the Fuzzy Combined Compromise Solution (F-CoCoSo) method was used to rank the alternatives. Results indicate that solar energy systems and wind-assisted propulsion consistently rank highest (with 3.35 and 2.92 performance scores) across different scenarios, followed by green propulsion technologies, while waste heat recovery and engine power limitation show lower performance. These findings not only provide a structured assessment of current technological options, but also offer actionable guidance for shipowners, operators, and policymakers seeking to prioritize investments in sustainable maritime operations. Full article

As a key medium in industry, lubricating oil plays a significant role in reducing friction, cooling sealing and transmitting power, which directly affects equipment life and energy efficiency. Traditional mineral-based lubricating oils rely on non-renewable petroleum, and they have high energy consumption and poor biodegradability (<30%) during the production process. They can easily cause lasting pollution after leakage and have a high carbon footprint throughout their life cycle, making it difficult to meet the “double carbon” goal. Bio-based lubricating oil uses renewable resources such as cottonseed oil and waste grease as raw materials. This material offers three significant advantages: sustainable sourcing, environmental friendliness, and adjustable performance. Its biodegradation rate is over 80%, and it reduces carbon emissions by 50–90%. Moreover, we can control its properties through processes like hydrogenation, isomerization, and transesterification to ensure it complies with ISO 6743 and other relevant standards. However, natural oils and fats have regular molecular structure, high freezing point (usually > −10 °C), and easy precipitation of wax crystals at low temperature, which restricts their industrial application. In recent years, a series of modification studies have been carried out around “pour point depression-viscosity preservation”. Catalytic isomerization can reduce the freezing point to −42 °C while maintaining a high viscosity index. Epoxidation–ring-opening modification introduces branched chains or ether bonds, taking into account low-temperature fluidity and oxidation stability. The deep dewaxing-isomerization dewaxing process improves the base oil yield, and the freezing point drops by 30 °C. The synergistic addition of polymer pour point depressant and nanomaterials can further reduce the freezing point by 10–15 °C and improve the cryogenic pumping performance. The life cycle assessment shows that using the “zero crude oil” route of waste oil and green hydrogen, the carbon emission per ton of lubricating oil is only 0.32 t, and the cost gradually approaches the level of imported synthetic esters. In the future, with the help of biorefinery integration, enzyme catalytic modification and AI molecular design, it is expected to realize high-performance, low-cost, near-zero-carbon lubrication solutions and promote the green transformation of industry. Full article

Esterases are ubiquitous enzymes found in all living organisms, including animals, plants, and microorganisms. They are involved in several biological processes, including the synthesis and breakdown of biomolecules, such as nucleic acids, lipids, and esters; phosphorus metabolism; detoxification of natural and artificial toxicants; polymer breakdown and synthesis; remodeling; and cell signaling. The present review focuses on the most industrially important esterases, namely lipases, phospholipases, cutinases, and polyethylene terephthalate hydrolases (PETases). Esterases are widely used in industrial and biotechnological applications. Notably, the biotechnological production of esters, including methyl acetate, ethyl acetate, vinyl acetate, polyvinyl acetate, and ethyl lactate, as an alternative to chemical production, represents a multi-billion-dollar industry. Currently, most enzymes (>75%) used in industrial processes are hydrolytic. Among them, lipases and phospholipases are primarily used for lipid modification. Lipases are the third most commercialized enzymes after proteases and carboxyhydrases, and their production is steadily increasing, currently representing over one-fifth of the global enzyme market. Esterases, particularly lipases, phospholipases, and cutinases, are employed in cosmetics, food, lubricants, pharmaceuticals, paints, detergents, paper, and biodiesel, among other industries. Overall, biotechnological production using enzymes is gaining global traction owing to its environmental benefits, high yields, and efficiency, aligning with green economy principles. Full article

Successful fertilization is essential for fruit bearing and yield enhancement, relying on male gametophyte which facilitates sexual reproduction by transferring the sperm cell to the ovule. To accomplish this task, pectate lyase is secreted to lubricate the sperm cell towards the female partner by different strategies. However, the specific impact of strawberry PL in male sterility and achene development remained elusive. Here, we systematically investigated the functions of diploid strawberry Fragaria vesca pectate lyase 1 (FvePL1), determining its localization in the cell wall and membrane. In situ hybridization presented its maximum expression in the anther, particularly the endothecium, connective tissue, and septum. Analysis of RNAi mutants and green fluorescent protein (GFP)-tagged overexpression lines demonstrated that the failure of FvePL1 significantly inhibited the fruit set due to stunted achenes. In addition, the deficiency of FvePL1 expression resulted in a 68.29% reduction in the number of pollen grains, a 73.27% decrease in pollen viability, morphological alterations of exine and intine, impaired pollen tube, and the inability of the sperm nucleus to reach its target due to the delayed and incomplete tapetal degeneration. In addition, the suppression of FvePL1 resulted in a 65.02% increase in survival rate withholding irrigation for 30 days, conferring enhanced drought tolerance by negatively influencing cell wall structure. Therefore, this study identified FvePL1 as a crucial regulator of pollen development, fertilization, and achene maturation and abiotic stress. These findings provide a framework for advancing research on the development of the male gametophyte in strawberry and even yield optimization in Rosaceous crops. Full article

The automotive industry is undergoing a transformative shift toward sustainability, driven by stringent environmental regulations, rising energy demands, and the pursuit of enhanced performance and efficiency. Lubricating materials play a pivotal role in reducing friction, wear, and energy losses in automotive systems, yet conventional lubricants, primarily petroleum-based, pose significant ecological and operational challenges. This review examines the development and performance of sustainable and advanced lubricant including bio-based oils, synthetic esters, nanolubricants, and ionic/solid lubricants for automotive applications. Drawing on tribological principles and recent advances in materials science, the article categorizes these lubricants based on source, chemical structure, and tribological behavior. A comparative framework is introduced to evaluate key performance indicators such as viscosity index, thermal stability, oxidation resistance, biodegradability, and compatibility with modern engine designs. The review also highlights emerging trends, including nanotechnology-based additives, green synthesis techniques, and novel antioxidant systems that enhance lubricant functionality and lifespan. Furthermore, a strategic research roadmap is proposed, outlining short-, medium-, and long-term priorities that integrate technical, environmental, and economic dimensions. By bridging foundational science with practical innovation, this article aims to guide researchers, manufacturers, and policymakers toward the adoption of high-performance, eco-compatible lubricants that support the transition to cleaner and more efficient mobility systems. Future directions and challenges in scaling, cost-effectiveness, and lifecycle assessment are discussed to guide innovation in this critical domain. Full article

The increased energy efficiency of electrified vehicles and their potential to reduce CO₂ emissions through the use of environmentally friendly materials are highlighted as reasons for the shift to electrified vehicles. Brief trends on the development of electric vehicles (EVs) have been discussed, presenting outstanding improvement towards the actualization of the green economy. The state of the art in lubrication has been thoroughly investigated as one of the factors influencing energy efficiency and the lifespan of machine components. As a result, many reports on the effectiveness of specific lubricants in electric vehicle applications have been developed. Good thermal and corrosion-resistant lubricants are necessary because of the emergence of several new tribological difficulties, especially in areas that interact with greater temperatures and currents. To avoid fluidity and frictional problems that may be experienced over its lifetime, a good viscosity level of lubricant was also mentioned as a crucial component in the formulation of EV lubricant. New lubricants are also necessary for the gearbox systems of electric vehicles. Furthermore, battery electric vehicles (BEVs) require a suitable cooling system for the batteries; thus, a compatible nano-fluid is recommended. Sustainable battery cooling options support global energy efficiency and carbon emission reduction while extending the life of EV batteries. The path for future advancements or the creation of the most useful and efficient EV lubricants is provided by this review study. Full article

This research reveals the anti-friction and anti-wear performance of lubricants using a castor oil base and a deep eutectic solvent (DES1) as an additive. To this end, DES1 was synthesized in a successful manner using DL-menthol and dodecanoic acid as components. Mass concentrations from 0.1 wt% up to 5 wt% of DES1 additives were chosen to formulate the lubricants. Friction experiments were conducted, yielding friction enhancements up to 4% compared to the castor oil base. Notably the greatest reduction was achieved for the lubricant with 0.1 wt% of DES1. In terms of the wear generated, the best anti-wear performance was achieved for the 0.5 wt% DES1 lubricant (with a wear reduction of 17%). Furthermore, by means of the profilometry of worn surfaces, it can be observed that the tribofilm formation of DES1 on steel surfaces is a potential lubrication mechanism. Full article

This study addresses the urgent demand for low-GWP refrigerant alternatives in rail vehicle air-conditioning systems by proposing a novel binary mixture, ZT01 (R13I1/R32 = 0.6/0.4 by mass), as a replacement for R407C. A comprehensive evaluation combining thermodynamic cycle modeling, refrigerant property analysis, and experimental validation shows that ZT01 delivers a coefficient of performance (COP) comparable to R407C, while providing a 45–49% improvement in volumetric cooling capacity, enabling smaller compressor displacement for the same cooling output, and reducing specific compressor work by 13–21%. In addition, ZT01 maintains a lower compression ratio, exhibits non-flammability, is compatible with POE lubricant, and has a GWP of only 308. Life Cycle Climate Performance (LCCP) analysis further indicates a 6.88% reduction in total carbon emissions and a 77.4% reduction in direct emissions compared to R407C, demonstrating that ZT01 is both technically feasible and environmentally sustainable for green retrofitting of rail vehicle HVAC systems. Full article

In response to the IMO’s decarbonisation strategy, hydrogen—especially green hydrogen—becomes a promising alternative fuel in shipping. This article provides a comparative analysis of two hydrogen propulsion technologies suitable for a service vessel (SOV) operating in offshore wind farms: hydrogen fuel cells and hydrogen-powered internal combustion engines. This study focuses on the use of liquid hydrogen (LH₂) stored in cryogenic tanks and fuel cells as an alternative to the previously considered solution based on compressed hydrogen (CH₂) stored in high-pressure cylinders (700 bar) and internal combustion engines. The research aims to examine the feasibility of a fully hydrogen-powered SOV energy system. The analyses showed that the use of liquefied hydrogen in SOVs leads to the threefold reduction in tank volume (1001 m³ LH₂ vs. 3198 m³ CH₂) and the weight of the storage system (243 t vs. 647 t). Despite this, neither of the technologies provides the expected 2-week autonomy of SOVs. LH₂ storage allows for a maximum of 10 days of operation, which is still an improvement over the CH₂ gas variant (3 days). The main reason for this is that hydrogen tanks can only be located on the open deck. Although hydrogen fuel cells take up on average 13.7% more space than internal combustion engines, they are lower (by an average of 24.3%) and weigh less (by an average of 50.6%), and their modular design facilitates optimal arrangement in the engine room. In addition, the elimination of the exhaust system and lubrication simplifies the engine room layout, reducing its weight and space requirements. Most importantly, however, the use of fuel cells eliminates exhaust gas emissions into the atmosphere. Full article

In this study, a green lubricating grease was prepared based on cellulose and epoxidized soybean oil (ESO). The cellulose extracted from the corn stover was functionalized using diphenylmethane diisocyanate (MDI), which enhances its compatibility and thickening ability in non-polar oil, and subsequently dispersed in ESO to form a stable gel-like bio-based grease. The functionalized surface of cellulose was characterized by FTIR, SEM, and XRD. And the rheological and tribological characteristics of the prepared bio-based grease were discussed. The superior lubricity and anti-wear properties of our bio-based grease are demonstrated by its lower friction and diminished wear relative to commercial lithium-based formulations. This work provides practical guidance for designing environmentally friendly grease for sustainable lubrication. Full article

Lubricating oil plays a critical role in protecting mechanical systems. Driven by sustainable development strategies, the development of high-performance, biocompatible green lubricants has become an urgent industry need. Biomass resources, characterized by wide distribution, renewability, and environmental friendliness, represent ideal raw materials for replacing petrochemical-based lubricants. In this study, renewable Xanthoceras sorbifolia oil was utilized as the feedstock. Branched modification was achieved via ring-opening esterification using 2-ethylhexanol (2-EH) as the modifier and tetrafluoroboric acid (HBF₄) as the catalyst. This epoxidation-branching modification process was synergistically combined with Nano-C₁₄MA/MMT treatment. This approach significantly reduced high-temperature kinematic viscosity loss while maintaining excellent low-temperature flow properties, resulting in an Xanthoceras sorbifolia oil-based lubricant with outstanding viscosity–temperature performance and low-temperature fluidity. At a Nano-C₁₄MA/MMT mass ratio of 0.3 wt% of the base oil, the lubricant demonstrated superior wide-temperature performance: KV₄₀ = 424.1 mm²/s, KV₁₀₀ = 50.8 mm²/s, VI = 180.8. The SP was reduced to −43 °C, exceeding the performance requirements of V-class environmentally friendly lubricants (e.g., synthetic ester oils). Furthermore, the coefficient of friction (COF) was 0.011 and the anti-wear scar diameter (AWSD) was 0.44 mm, indicating lubrication performance significantly superior to SN-class lubricants (specifications: COF < 0.12, AWSD < 0.50 mm). Full article

The growing accumulation of waste lubricating oil presents serious environmental issues, calling for sustainable management solutions. This research discusses the creation of FeNi/TiO₂ nanocatalysts that were synthesized through an eco-friendly method utilizing grape seed extract (GSE) as a natural reducing agent for the catalytic pyrolysis of waste lubricating oil. The nanocatalyst was produced using the microemulsion technique and refined via Response Surface Methodology (RSM) to optimize its catalytic performance. Pyrolysis was carried out at 400 °C, leading to a significant conversion of waste oil into valuable fuel. The FeNi/TiO₂ nanocatalyst exhibited exceptional capabilities in facilitating the breakdown of heavy hydrocarbons into lighter fuel fractions while reducing unwanted byproducts. GC-MS analysis demonstrated the prevalence of C6–C20 hydrocarbons in the pyrolysis oil, underscoring its potential as a high-quality alternative fuel similar to traditional diesel. This study aids in the progress of environmentally sustainable waste-to-energy technologies, offering a promising pathway for effective fuel production and hazardous waste management. Full article