Search Results (251)

Hydrolyzed polyacrylamide stabilized oil-in-water emulsions are highly persistent because the polymer strengthens both continuous-phase rheology and the oil–water interfacial film, making demulsification difficult in polymer-flooding produced liquids. Here, an hydrolyzed polyacrylamide degrading bacterium, Delftia lacustris EPDB-8, was isolated, and its ability to destabilize hydrolyzed polyacrylamide-containing emulsions was investigated from molecular, bulk rheological, and interfacial perspectives. EPDB-8 effectively degraded HPAM, causing marked reductions in total organic carbon, total nitrogen, absolute zeta potential, and polymer molecular weight, with an approximately 63-fold decrease after 7 days. SEM, FT-IR, and GPC analyses showed that biodegradation proceeded through deamidation and random chain scission, collapsing the polymer network and generating low-molecular-weight fragments. Driven by bacterial hydrolyzed polyacrylamide degradation, these structural alterations disrupted the viscoelastic composite interfacial film formed by hydrolyzed polyacrylamide and indigenous surface-active species, directly causing emulsion stabilization to shift from polymer-assisted viscous and steric protection to a less effective asphaltene-dominated interfacial structure and thereby accelerating droplet aggregation, coalescence, and phase separation. Although bacterial cells exerted a transient particle-assisted interfacial effect, long-term emulsion stability remained governed by polymer integrity. This study establishes a mechanistic link between hydrolyzed polyacrylamide biodegradation and the rheological and interfacial evolution governing emulsion breakdown, providing a cost-effective and environmentally benign biological strategy for demulsification and treatment of polymer-flooding produced water. These findings offer practical guidance for the design of microbial-based produced-water treatment systems and contribute to the sustainable management of oilfield wastewater generated during enhanced oil recovery operations. Full article

Constructing inverted wedge-shaped hydrophilic channels with a small apex angle on surfaces with wettability patterns is an effective strategy to promote efficient and complete droplet detachment, which is crucial for applications such as condensation heat transfer and self-cleaning. However, a comprehensive understanding of how wedge geometry parameters affect droplet dynamics has not been established. In this study, we systematically investigate the dynamics of droplet formation and detachment within inverted wedge-shaped superhydrophilic channels fabricated by laser etching on hydrophobic or superhydrophobic substrates. Four distinct droplet detachment mechanisms are revealed. Our results indicate that, within the experimental parameters tested, a slender channel geometry—featuring a narrow upper base, a minimized lower base, and sufficient height—combined with a superhydrophobic substrate, promotes high-position droplet formation, extends the droplet sliding distance, and significantly reduces resistance. This synergy leads to the most efficient detachment mechanism: inertia-driven direct shedding. For the tested configurations, the C1.2/0/40 channel achieved the highest recorded detachment frequency of 318 min⁻¹ at a flow rate of 0.5 mL/min. Furthermore, droplet rebound at the channel tip is observed in some configurations, where two to three droplets must form sequentially and coalesce to trigger a single detachment event. This work provides actionable geometric design strategies for engineering surfaces capable of directional and highly efficient droplet detachment. Full article

Access to clean water remains a critical global challenge, particularly in arid and fog-rich regions where conventional resources are limited. Fog water harvesting has emerged as a low-energy alternative; however, the performance of traditional collectors (typically 3–10 L m⁻² day⁻¹) remains constrained by inefficient droplet capture and transport. This review provides a systematic and critical analysis of recent advances in membrane-based fog harvesting technologies, focusing on material design, surface engineering, and structural optimization. The analysis shows that nanostructured and electrospun membrane systems can enhance water collection rates to ~20–60 L m⁻² day⁻¹, representing up to a 5–6 times improvement over conventional meshes. Furthermore, biomimetic and Janus wettability designs significantly improve droplet nucleation and directional transport, while hierarchical micro/nanostructures accelerate coalescence and runoff dynamics. At the structural level, optimized collector geometries (vertical harp designs) demonstrate ~3–4 times higher collection efficiency compared to traditional Raschel mesh due to reduced clogging and enhanced drainage. Despite these advances, key challenges remain, including material durability, fouling resistance, lack of standardized testing protocols, and limited large-scale validation. This review identifies critical design–performance relationships and proposes a framework linking surface wettability, morphology, and environmental parameters to harvesting efficiency. Future directions emphasize the development of durable, scalable membrane systems and the integration of fog harvesting with hybrid water supply technologies. Full article

Air flotation is widely used in wastewater treatment for the removal of emulsified oils and suspended solids. The complex flow disturbances generated during the flotation process play a critical role in determining separation efficiency. This study employs the volume-of-fluid (VOF) method within the OpenFOAM framework to simulate the aggregation and rising behavior of microbubbles (40–100 μm) and oil droplets under various perturbation conditions. The effects of different airflow disturbance patterns on the flotation dynamics of oil–gas compounds are systematically investigated. Results show that negative pulsation promotes the rising of bubble–oil aggregates, whereas positive pulsation hinders their coalescence and upward motion. Furthermore, recirculation vortices induced by surface disturbances increase the residence time of oil–gas compounds in the water column, thereby affecting overall separation performance. The findings demonstrate that introducing vertical upward flow and bilateral oblique upward airflow can enhance flotation efficiency. This work provides insights into optimizing airflow configurations for improved oil removal in wastewater treatment applications. Full article

Deletion of the tumor suppressor gene phosphatase and tensin homolog (PTEN) in hepatocellular carcinoma (HCC) is associated with a poor response to therapy and reduced survival. In mice, the deletion of PTEN in hepatocytes generates steatosis; however, on the background of steatosis not all emerging HCC cells lack PTEN, suggesting that steatosis confers a metabolic liability to proliferating PTEN-deficient hepatocytes. Here, we show that PTEN-deficient HepG2 cells develop terminal stress in the endoplasmic reticulum (ER) and profound apoptosis when exposed to a mixture of oleic and palmitic acids, while control cells do not. Lipidomic analyses before and after the treatment indicate a higher increase in triglycerides in PTEN KO cells, as well as profound differences in phospholipid concentrations. Although the triglyceride content increases, the coalescence into lipid droplets was impaired in the KO cells, together with a reduction in β-oxidation. Xenograft studies showed that PTEN KO HCC tumors progressed faster than did the control tumors when mice were fed with normal chow and slower under a high-fat diet. We suggest that while the health risks of a fatty acid-rich diet to liver function and the increased propensity to develop HCC are prominent, once a PTEN-deficient HCC has been established, it exposes vulnerability to lipid overload that can be exploited through diet and pharmacological interventions. Full article

Despite extensive pore-scale studies on oil–water displacement, quantitative understanding of the dynamic evolution of residual oil morphology and waterflooding efficiency in geologically heterogeneous sandstones remains limited, particularly under large water-injection multiples. To better understand pore-scale oil–water distribution and its influence on enhanced oil recovery, this study utilized Micro-CT combined with SEM-EDS to examine the 3D pore structure and oil–water phase evolution in a heterogeneous sandstone sample from the Xiayang Formation, Wushi Sag, Zhanjiang. Mineralogical analyses reveal that dolomite cementation and vermicular kaolinite infilling introduce strong pore-scale heterogeneity by selectively reducing pore connectivity and permeability, posing challenges for uniform fluid displacement. A 30% KI solution was used to enhance X-ray attenuation of the aqueous phase, enabling clear discrimination between oil and water. Micro-CT reconstructions reveal a relatively uniform pore network dominated by medium-to-large intergranular pores. As the water-injection multiple increases, water progressively invades larger pores, while residual oil is immobilized by capillary forces within micro-throats, forming isolated clusters. The oil-droplet size distribution broadens from a narrow range (50–100 µm) to a wider one (200–300 µm), indicating interfacial destabilization and droplet coalescence. Quantitative analysis indicates that oil saturation decreases from approximately 90% to 36%, while waterflooding efficiency increases rapidly to ~45% at 1 PV and gradually approaches a plateau of ~60% beyond 500–1000 PV. This waterflooding plateau is attributed to capillary trapping and pore-scale connectivity limitations imposed by mineral-induced heterogeneity, which prevent further mobilization of residual oil despite continued water injection. This study advances pore-scale waterflooding research by combining mineralogical heterogeneity with long-term micro-CT imaging, revealing the pore-scale mechanisms controlling residual oil evolution and ultimate waterflooding limits in realistic sandstone. Full article

The term “pristine emulsion” is used for differentiating emulsions that consist of only water and oil with no surfactant from the Pickering emulsions, which are also surfactant-free but stabilized with colloidal particles. We review 22 papers dedicated to such emulsions prepared from a wide variety of liquids. We studied here the evolution of one such emulsion, hexadecane-in-water at 4% vl, over a long period of time, from days to weeks. We discovered that the droplet size grows with time, with a rate that depends on mixing conditions, which supports a coalescence hypothesis. However, this coalescence is unusual because the size reaches a certain constant value, which contradicts typical coalescence behavior. To explain this peculiarity and such emulsification in general, we employ a theoretical model that was developed for explaining pristine nano-bubble stability. We hypothesize the existence of a layer of structured water molecules at the interface, following Eastoe and Ellis (Adv in Colloid and Interface Sci., 134–135, 89–95, 2007) and others. We point out that the Electric Double Layer exerts a force on the water dipole moments in this layer (dielectrostatic force) that compensates Kelvin’s pressure. The droplet size calculated using this model is close to the measured size. The second factor associated with this layer is the repulsion of the water dipole moments, which we show can compensate for the surface tension tangential to the interface. After ruling out alternative hypotheses with our data, we conclude that the model suggested for explaining the stability of nano-bubbles is also consistent with our results for these “pristine emulsions”. Full article

Foods for special medical purposes play a critical role in clinical nutritional support, especially oil-in-water emulsions characterized as having high energy density, which could provide efficient energy for patients with insufficient intake or those requiring fluid restriction. The included oil types are the critical determinants of emulsion stability, which, in turn, governs digestive behavior, absorption efficiency, and ultimate bioavailability of the delivered nutrients. However, such emulsions face stability challenges during storage and application. In the present study, high-energy-density fat emulsions formulated with six typical oils, which contained 50% oil content, were prepared and systematically analyzed in terms of their particle size, zeta potential, microstructure, centrifugal stability, multiple light scattering, and rheological properties. The results indicated that oils with medium-chain fatty acids, due to their compact molecular structure and low viscosity, facilitated the formation of finer droplets and promoted the orderly arrangement of phospholipids at the interface of the emulsion system, leading to the formation of a dense, elastic interfacial layer and a gel network structure. Its marked shear-thinning characteristic and lowest frequency dependence contributed to desirable processing and storage stabilities. In contrast, long-chain triacylglycerols, especially those enriched with monounsaturated and saturated fatty acids, tended to form rigid but insufficiently elastic interfacial layers, which were unfavorable for resisting coalescence and phase separation induced by external forces. Highly unsaturated oils, on the contrary, exhibited medium levels for emulsion stability. Further analysis of the relationship between the physicochemical properties of oils and the characteristics of emulsions revealed that fatty acid species in the oil phase were the key determinants of emulsification behavior. It was therefore speculated that oils rich in medium-chain fatty acids with a moderate degree of unsaturation, especially including selected ω-3 and ω-6 fatty acids, could improve emulsion stability and fatty acid balance synchronously. This study provides a theoretical basis and technical support for the formulation design and stability control of high-energy-density fat emulsions. Full article

Tunicate (marine invertebrates)-derived cellulose nanocrystals (T-CNC) possess unique structural and physicochemical properties compared to other wood-based CNCs. This study aimed to characterize and utilize T-CNC as a stabilizer in Pickering emulsion (PE), highlighting a sustainable alternative to conventional surfactant-based emulsifiers. Characterization of T-CNC revealed a rod-shaped morphology with dimensions of 1694 ± 925 nm in length and 13 ± 3 nm in width, resulting in an aspect ratio of 122 ± 45, and high crystallinity (87.6%). Its zeta potential ranged from −4.4 to −45.5 mV across pH 2–10 and contact angles <50° indicate strong water wettability. T-CNC at 0.2%, 0.3%, and 0.4% (w/w) at pH 3 and 5 was used to prepare 20 wt% oil-in-water PE using a high-shear homogenizer followed by ultrasonication. Ultrasonication significantly improved the emulsion stability compared to only high-shear homogenization, decreasing droplet size by 31.4–50.8% and 55.7–89.3% for pH 3 and pH 5, respectively. PEs developed at pH 3 demonstrated smaller droplet sizes, better stability with minimal coalescence after 7 days, and enhanced gel-like rheological behaviour compared to PEs at pH 5, which displayed flocculation and coalescence. The gel strength of the pH 3 PEs increased with T-CNC concentration, as evidenced by progressively denser droplet packing, consistent with stronger interfacial anchoring (higher detachment energy) and reduced coalescence. This study underscores T-CNC’s superior efficiency in stabilizing PEs at low concentrations, offering a green, high-performance solution for food, cosmetic, and pharmaceutical applications. Full article

Oily sludge is a complex emulsified waste consisting of water, oil, and solid particles. Conventional treatments are often inefficient, energy-intensive, and prone to causing secondary pollution. This study proposes a green demulsification technology based on ozone micro–nanobubbles (O₃MNBs) by constructing an experimental system to analyze its effects and mechanisms of action on oily sludge treatment. The O₃MNBs exhibited a mean particle size of 831 nm and generated a substantial amount of hydroxyl radicals (·OH, 250.4 μmol·L⁻¹) in situ. Compared with conventional aeration, the dissolved ozone concentration and residence time in water of O₃MNBs increased by 192% and 213%, respectively. During bubble collapse, intense pressure waves and high-speed microjets were generated to disrupt sludge aggregates, promoting the dispersion of sludge particles while simultaneously stripping oil films. Thus, the oil removal rate reached 41.5%, demonstrating the high demulsification efficiency of O₃MNBs. Furthermore, ozone and ·OH attacked alkane C-H bonds in the oil phase, oxidizing hydrophobic films into hydrophilic products and decomposing surfactants that stabilize emulsions. This process promoted oil droplet coalescence and degradation into small organic molecules. After O₃MNB treatment, the absorption peak of alkane C-H bonds gradually reduced, while a new C=O absorption peak appeared. This study provides a theoretical foundation and technical support for environmentally sustainable treatment of oily sludge by O₃MNB application, offering an effective alternative to chemical demulsification without secondary pollution. Full article

The collision dynamics of binary seawater droplets are pivotal in marine engineering applications, like spray desalination and engine cooling. While high-fidelity simulations can resolve these dynamics, they are computationally prohibitive for rapid design and analysis. This study introduces the first interpretable machine learning (ML) framework to predict and elucidate the collision outcomes of head-on binary seawater droplets. A high-fidelity numerical dataset, generated via Modified Coupled Level Set-VOF (M-CLSVOF) simulations across a broad Weber number (We) range, serves as the foundation for training multiple classifiers. Among the tested algorithms, the Random Forest model achieved superior performance with 96.2% accuracy. The model’s predictions precisely identified the critical Weber number for the transition from coalescence to reflexive separation at We ≈ 22.3 for seawater. Moving beyond black-box prediction, we employed SHapley Additive exPlanations (SHAP) to quantitatively deconstruct the model’s decision-making process. SHAP analysis confirmed the dominance of the Weber number (75% contribution) and revealed the context-dependent role of the Reynolds number (25% contribution) in modulating the collision outcome. Furthermore, a comparative analysis with freshwater droplets quantified a 6% elevation in the critical Weber number for seawater, attributed to salinity-induced modifications in fluid properties. Finally, a machine-learned regime map in the We-Ohnesorge space was constructed, delineating the coalescence and separation boundaries. This work establishes ML as a powerful, interpretable surrogate model that not only delivers rapid, accurate predictions but also extracts fundamental physical insights, offering a valuable paradigm for optimizing marine spray systems. Full article

The emulsification of a molten fusible metal alloy in a liquid epoxy matrix with its subsequent curing is a novel way to create a highly concentrated phase-change material. However, numerous challenges have arisen. The high interfacial tension between the molten metal and epoxy resin and the difference in their viscosities hinder the stretching and breaking of metal droplets during stirring. Further, the high density of metal droplets and lack of suitable surfactants lead to their rapid coalescence and sedimentation in the non-cross-linked resin. Finally, the high differences in the thermal expansion coefficients of the metal alloy and cross-linked epoxy polymer may cause cracking of the resulting phase-change material. This work overcomes the above problems by using nanosilica-induced physical gelation to thicken the epoxy medium containing Wood’s metal, stabilize their interfacial boundary, and immobilize the molten metal droplets through the creation of a gel-like network with a yield stress. In turn, the yield stress and the subsequent low-temperature curing with diethylenetriamine prevent delamination and cracking, while the transformation of the epoxy resin as a physical gel into a cross-linked polymer gel ensures form stability. The stabilization mechanism is shown to combine Pickering-like interfacial anchoring of hydrophilic silica at the metal/epoxy boundary with bulk gelation of the epoxy phase, enabling high metal loadings. As a result, epoxy shape-stable phase-change materials containing up to 80 wt% of Wood’s metal were produced. Wood’s metal forms fine dispersed droplets in epoxy medium with an average size of 2–5 µm, which can store thermal energy with an efficiency of up to 120.8 J/cm³. Wood’s metal plasticizes the epoxy matrix and decreases its glass transition temperature because of interactions with the epoxy resin and its hardener. However, the reinforcing effect of the metal particles compensates for this adverse effect, increasing Young’s modulus of the cured phase-change system up to 825 MPa. These form-stable, high-energy-density composites are promising for thermal energy storage in building envelopes, radiation-protective shielding, or industrial heat management systems where leakage-free operation and mechanical integrity are critical. Full article

Widely used in treating oil mist aerosols generated from metalworking processes, conventional gas–liquid coalescing filters face drawbacks such as increased energy consumption, performance limitations, and shortened service life due to high steady-state pressure drop. To address these issues, this study proposes an innovative design for a filter based on wettability-regulated gradient pore structure. Using glass fiber filter media with different pore size parameters as the substrate and incorporating an intermediate mesh layer, a three-layer filtration structure of “large-pore filtration layer—mesh layer—small-pore filtration layer” was constructed. The surface wettability of each layer was regulated by a self-developed surface modifier, producing gradient pore structure filters with different wettability configurations. The variations in key performance parameters, including steady-state pressure drop, filtration efficiency, saturation, and service life, were systematically evaluated for these configurations. Experimental results demonstrated that the configuration with an “oleophobic large-pore filtration layer—mesh layer—oleophilic small-pore filtration layer” yielded the best overall performance. Analysis based on the “jump-channel” model indicated that the gradient pore structure achieves progressive droplet filtration and optimizes droplet coalescence and capture through wettability differences. Consequently, while maintaining exceptional filtration efficiency (>99%), this configuration significantly reduces the steady-state pressure drop by over 34% and effectively extends the service life by more than 66%. This wettability-regulated gradient pore structure provides a novel technical pathway for addressing the challenges of balancing pressure drop and filtration efficiency, as well as extending the service life, in gas–liquid coalescing filters. Full article

In the context of global energy demands, the efficient demulsification of highly stable heavy crude oil emulsions remains a critical challenge. This study systematically investigated the demulsification mechanisms of two demulsifiers (P1# and P2#) through multi-dimensional characterisation and performance evaluation. The results indicated that asphaltenes and resins can strengthen the oil–water interfacial film and stabilise the emulsion due to their unique structural properties. FTIR and ¹HNMR analyses showed that both demulsifiers contained polar groups and alkyl chains; however, P1# exhibited higher viscosity and lower surface tension, which favored its rapid adsorption at the interface. Demulsification tests at 60 °C demonstrated that P1# achieved superior efficiency (92.44% demulsification efficiency (DE) in 120 min versus 82.31% for P2#), attributable to its enhanced ability to displace asphaltene/resin at the oil-water interface. Turbiscan stability analysis and microscopic observations confirmed that P1#-treated emulsions underwent faster droplet coalescence and significant interfacial film disruption. Mechanistic studies indicated that the demulsifiers competitively adsorb at the interface, thereby weakening film cohesion through steric hindrance and charge redistribution. XRD and FTIR analyses suggested that interactions between the demulsifier and the asphaltene/resin increased interlayer spacing and reduced crystallinity. Zeta potential and interfacial tension measurements further highlighted P1#’s ability to neutralize negative charges (from −14.52 mV to +8.3 mV) and reduce the IFT (from 28.5 mN/m to 12.1 mN/m), thereby promoting droplet aggregation. This study helps elucidate the mechanism of emulsion phase transition induced by demulsifiers and provides theoretical support for improving the demulsification efficiency of crude oil emulsions. Full article

This study explores the fabrication and characterization of Pickering high internal phase emulsions (P-HIPEs) stabilized by soy protein isolate (SPI) and coix polysaccharide (CP) complex. CP exhibited high purity (95.29%) with a molecular weight of 5.53 × 10⁵ Da and was predominantly composed of glucose, as confirmed by monosaccharide analysis and FT-IR spectroscopy. SPI/CP complexes formed well-dispersed nanoparticles with optimal stability at 2% CP concentration, demonstrated by minimal particle size and enhanced zeta potential. P-HIPEs stabilized by these complexes showed excellent physical stability without phase separation or oil leakage, with the creaming index decreasing as particle concentration increased, reaching optimal stability at 12% SPI/CP and pH 9. Particle size and zeta potential measurements indicated smaller, more uniform droplets and intensified electrostatic repulsion under these conditions, effectively preventing droplet coalescence. Confocal microscopy revealed a dense, multilayered interfacial network formed by SPI/CP complexes around oil droplets, enhancing emulsion stability. Rheological analyses confirmed that P-HIPEs exhibited elastic solid-like gel behavior with pronounced shear-thinning and superior thixotropic recovery at 12% SPI/CP and alkaline pH, highlighting improved gel strength and structural integrity. These findings demonstrate the critical influence of SPI/CP concentration and pH on the physicochemical, microstructural, and rheological properties of P-HIPEs, offering valuable insights for developing stable emulsions with enhanced performance and applicability in food systems. Notably, the results emphasize the critical role of SPI/CP concentration and pH in achieving optimal emulsion stability and rheological properties. Full article