Hydrate Film Research Articles

A pH ultra-sensitive hydrated iridium oxyhydroxide films electrochemical sensor for label-free detection of Vibrio parahaemolyticus

Vibrio parahaemolyticus (V. parahaemolyticus) is a major foodborne pathogen, which can cause serious foodborne illnesses like diarrhoea. Rapid on-site detection of foodborne pathogens is an ideal way to respond to foodborne illnesses. Herein, we provide an electrochemical sensor for rapid on-site detection. This sensor utilized a pH-sensitive metal-oxide material for the concurrent isothermal amplification and label-free detection of nucleic acids. Based on a pH-sensitive hydrated iridium oxide oxyhydroxide film (HIROF), the electrode transforms the hydrogen ion compound generated during nucleic acid amplification into potential, so as to achieve a real-time detection. The results can be transmitted to a smartphone via Bluetooth. Moreover, HIROF was applied in nucleic acid device detection, with a super-Nernst sensitivity of 77.6 mV/pH in the pH range of 6.0–8.5, and the sensitivity showed the best results so far. Detection of V. parahaemolyticus by this novel method showed a detection limit of 1.0 × 103 CFU/mL, while the time consumption was only 30 min, outperforming real-time fluorescence loop-mediated isothermal amplification (LAMP). Therefore, the characteristics of compact, portable, and fast make the sensor more widely used in on-site detection.

Effect of Embedded g-C3N4 Nanosheets on the Hydration and Thermal Response Behavior of Cross-Linked Thermoresponsive Copolymer Films.

The effect of embedded graphitic carbon nitride (g-C3N4) nanosheets on hydration and thermal response behavior of cross-linked thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate), abbreviated as P(MA-co-MA300), thin films is probed by white light interferometry. Compared with that of the cross-linked pure P(MA-co-MA300) films, the surface roughness of the cross-linked hybrid films is slightly increased, which is caused by the minor aggregation of g-C3N4 nanosheets during the spin-coating process. After exposure to a water vapor atmosphere, both cross-linked pure and hybrid films can absorb water and swell. However, the introduction of g-C3N4 not only induces a larger hydration extent but also triggers a nonlinear transition behavior upon heating. This prominent difference might be related to the residual hydrophilic groups (-NH2 and N-H) on the surface of g-C3N4 nanosheets, which enhance the interaction and absorption capability for water molecules in the hybrid films. Upon further increasing the amount of embedded g-C3N4 nanosheets in films, more hydrogen bonds are formed and a larger hydration extent of films is observed. To break all of the hydrogen bonds in films, a higher transition temperature (TT) is required. The observed hydration and transition behaviors of hybrid films can be used to design hydrogel-based films for hydrogen evolution or wastewater treatment.

Effect of anti‐Agglomerants on carbon dioxide hydrate formation in oil–water systems

AbstractThe experiments in high‐pressure pipelines simulate the formation and fluid of hydrate under deep‐sea conditions, which has practical significance for the deep‐sea landfill of carbon dioxide (CO2) and the safe running of oil and gas pipelines. In this paper, pure water, white oil, CO2, and arquad 2C‐75 were used to study the formation and flow characteristics of CO2 hydrate in the oil–water system with the help of a loop device, and the growth morphology of hydrate was observed through the view‐window on the loop. The experimental results show that in the low water cut system without anti‐agglomerates, hydrate mainly forms on the surface of water droplets and the surface of the free water layer at the bottom of the loop. In the high water cut system, hydrate forms on the pipe wall in the form of hydrate film. Increasing water cuts can shorten the induction period of hydrate formation. Anti‐agglomerates in the oil–water system can inhibit the growth of hydrate film on the pipe wall effectively. Anti‐agglomerates can shorten the induction time of hydrate formation.

The dual action of N2 on morphology regulation and mass-transfer acceleration of CO2 hydrate film

The morphology characteristics of CH4, CO2 and CO2+N2 hydrate film forming on the suspending gas bubbles are studied using microscopic visual method at supercooling conditions from 1.0 to 3.0 K. The hydrate film vertical growth rate and thickness along the planar gas-water interface are measured to study the hydrate formation kinetics and mass transfer process. Adding N2 in the gas mixture plays the same role as lowering the supercooling conditions, both retarding the crystal nucleation and growth rates, which results in larger single crystal size and rough hydrate morphology. N2 in the gas mixture helps to delay the secondary nucleation on the hydrate film, which is beneficial to maintain the pore-throat structure and enhance the mass transfer. The vertical growth rate of hydrate film mainly depends on the supercooling conditions and gas compositions but has weak dependence with the experimental temperature and pressure. Under the same gas composition condition, the final film thickness shows a linear relationship with the supercooling conditions. The mass transfer coefficient of CH4 molecules in hydrates ranges from 4.54 to 7.54×10–8 mol·cm–2·s–1·MPa–1. The maximum mass transfer coefficient for CO2+N2 hydrate occurs at the composition of 60% CO2+40% N2, which is 3.98×10–8 mol·cm–2·s–1·MPa–1.

Study on pre-oxidation of silver concentrate and leaching behaviour of Zn, Cu and In during oxygen-pressure leaching

Given the limitations of current processing methods and the potential of high recovery of silver as a flotation concentrate, this study proposes a pre-oxidation followed by oxygen pressure sulphuric acid leaching route for zinc, copper and indium and thoroughly examines the alteration in micro-morphology of the silver concentrate of 1.22% Pb, 3010 g/t Ag and 649 g/t In. Under the optimal conditions of a sulphuric acid pre-oxidation temperature of 60 °C, and an acid-to-ore mass ratio of 0.6, over 15 h, the PO and -OH polar groups of flotation reagents on the surface of silver concentrate particles are effectively neutralized through sulphuric acid oxidation. This action prevents the formation of a hydration film and mineral inclusions, thereby facilitating the efficient leaching of valuable elements. With a set reaction temperature of 155 °C, an initial acidity of 160 g/L, a reaction time of 180 min, an oxygen partial pressure of 0.8 MPa and a liquid-to-solid ratio of 7 mL/g, the leaching efficiency of Zn, Cu and In in the silver concentrate reach 94.8%, 98.4% and 91.1%, respectively while the lead and silver grades in the leach residue increase to 2.88% and 7754 g/t, respectively.

Carbon dioxide hydrate crystallization thickening & morphology in a micro-confined environment for carbon capture & sequestration processes

Carbon dioxide capture and sequestration (CCS) are critical processes that are necessary to mitigate the impacts of climate change. In pipelines used for CCS and for ocean sequestration, the formation of CO2 hydrates can occur and be detrimental to the safety and integrity of the CCS equipment and process. Understanding the crystallization thickening behavior of CO2 hydrates is vital for understanding hydrate formation in CO2 pipelines and in other CCS applications, such as sequestration and CO2 capture or storage. In this study, a microfluidic chip reactor was used to crystalize and thicken CO2 hydrates at the channel walls. The morphology of the CO2 hydrates was visually analyzed and quantified using in situ Raman spectroscopy. Two hydrate layers were consistently observed. An annealed, dense layer of hydrate shared an interface with liquid water, while a porous hydrate layer shared an interface with CO2 gas. Capillary-like pore spaces could be observed in the porous layer, which confirms one proposed mechanism for hydrate film thickening. Subcooling (0.5–1.5 K), pressure (2.51, 3.10 MPa), and flow rate of CO2 (0.167, 1.67 mm3/s) were studied for their impact on the overall CO2 hydrate film thickness over time. Over the ranges of these chosen parameters, only CO2 flow rate was found to have a significant impact on the thickening of CO2 hydrates, and a higher flow rate led to thicker crystalline hydrate films. A first principles mass transfer model for hydrate film thickness was developed and applied to the measurement data collected for overall hydrate film thickness.

Effects of Salinity on the Macroscopic and Microscopic Evolution Characteristics of Methane Hydrate Films on Bubble Surfaces

Effects of Salinity on the Macroscopic and Microscopic Evolution Characteristics of Methane Hydrate Films on Bubble Surfaces

Kinetics and morphology of gas hydrate formation from MEG solution in under-inhibited systems

Natural gas hydrate blockages pose a major risk to deepwater oil and gas development. Thermodynamic under-inhibition is a cost-effective hydrate management strategy, but the impact of mono ethylene glycol (MEG) on hydrate formation kinetics and mass transfer at the gas–water interface requires further understanding for hydrate-related flow assurance. This study investigates the kinetics and morphology of hydrate growth from MEG solutions using in situ micro X-ray CT and a macro transparent reactor. MEG concentration emerged as the primary factor influencing hydrate growth morphology. Findings revealed that MEG alters the growth morphology of gas hydrates by inhibiting the formation of a hydrate film at the gas–liquid interface and inducing flocculent hydrate growth within the solution. MEG can also induce the formation of low-saturation hydrates, with no significant self-inhibition observed at concentrations below 20 %. Over time, a dense hydrate shell tended to form on the surface of the hydrate lump, increasing the risk of blockage. Additionally, it was observed that subcooling also affects the hydrate growth morphology; higher subcooling accelerates the hydrate growth rate and increases the density of the formed hydrate. This research explored the mechanisms underlying hydrate formation in under-inhibited systems, aiming to extend the safe operational boundary for oil and gas transportation and provide theoretical support for deepwater hydrate management.

Interfacial rheology of cyclopentane hydrate formation: Insights into mechanical behavior and inhibitor efficiency

Hydrates are crystalline solids with an ice-like texture, which are formed when light hydrocarbon molecules and water combine to form a specific ordered structure. Hydrate formation begins at the water–hydrocarbon interface, which highlights the critical role that interfacial rheology plays in this process. Despite the significance of this interface in hydrate formation, a gap in research persists, particularly in employing shear rheology approaches. This study helps to fill this void by investigating the mechanical and flow properties of the interface, using a feature in a rotational rheometer, a “double wall ring cell,” for precise temperature control. Cyclopentane serves as the hydrate former, allowing experimentation under atmospheric pressure and varied temperatures. Protocols explore temperature and hydrocarbon concentrations, with emphasis on ice crystal involvement in hydrate formation initiation. Following complete saturation of the hydrocarbon/water interface by hydrates, interfacial elastic and viscous moduli are obtained through strain sweeps to assess hydrate film fragility and mechanical response. Additionally, the impact of aging time and shear type (static or dynamic) on hydrate stiffness is examined. Tests with thermodynamic inhibitors, such as sodium chloride and monoethylene glycol, demonstrate significant induction time extension. Furthermore, systematic changes in the shear rate are investigated to comprehensively understand their influence on hydrate film characteristics and properties under varying shear history conditions. This study reveals that increasing shear rate correlates with decreased viscosity of the hydrate film, indicative of non-Newtonian behavior. Overall, this research sheds light on the nuanced dynamics of the water–hydrocarbon interface in hydrate formation and mitigation.

Promotion mechanism of carbon dioxide hydrate formation by l-Methionine and its competitive effects with NaCl

The growth kinetics and macroscopic morphology evolution of CO2 hydrate promoted by l-Methionine (L-Met) in NaCl aqueous solutions in a wide range of mass fractions were systematically investigated. 0.05 wt% was the threshold mass fraction of L-Met to have prominent promotion effects in a batch mode. The addition of NaCl could suppress its promotion performance, while it could be regained by further addition of L-Met to 1.0 wt%. Porous feature and wall-climbing phenomena of CO2 hydrate were obvious in the presence of L-Met while it could be suppressed by NaCl. The tangential (lateral) growth rate of the hydrate film on planar pure water surface was the highest while both L-Met and NaCl could decrease it. For L-Met, it was the highest at 0.05 wt%. Special ball-like, mosaic-like and sword-like appearances of CO2 hydrates were found. Both the adsorption-capillary effects of L-Met and the hydration effects of L-Met and NaCl were thought to account for all the phenomena and a detailed scenario was proposed and discussed. A macroscopic growth model based on the tangential growth rates of hydrate films was proposed and evaluated.

Hierarchical Chiral Calcium Silicate Hydrate Films Promote Vascularization for Tendon-to-Bone Healing.

Revascularization after rotator cuff repair is crucial for tendon-to-bone healing. The chirality of materials has been reported to influence their performance in tissue repair. However, data on the use of chiral structures to optimize biomaterials as a revascularization strategy remain scarce. Here, calcium silicate hydrate (CSO) films with hierarchical chirality on the atomic to micrometer scale are developed. Interestingly, levorotatory CSO (L-CSO) films promote the migration and angiogenesis of endothelial cells, whereas dextral and racemic CSO films do not induce the same effects. Molecular analysis demonstrates that L-chirality can be recognized by integrin receptors and leads to the formation of focal adhesion, which activates mechanosensitive ion channel transient receptor potential vanilloid 4 to conduct Ca2+ influx. Consequently, the phosphorylation of serum response factor is biased by Ca2+ influx to promote the vascular endothelial growth factor receptor 2 signaling pathway, resulting in enhanced angiogenesis. After implanted in a rat rotator cuff tear model, L-CSO films strongly enhance vascularization at the enthesis, promoting collagen maturation, increasing bone and fibrocartilage formation, and eventually improving the biomechanical strength. This study reveals the mechanism through which chirality influences angiogenesis in endothelial cells and provides a critical theoretical foundation for the clinical application of chiral biomaterials.

Study of CO2 hydrate formation on the surface of residue shell from dissociated CH4 hydrate

The use of hydrates to store CO2 is considered an effective method that can be implemented. However, the problems of interfacial hydrate film formation and low mass transfer efficiency when forming CO2 hydrate under static conditions still need to be solved. This study compared the growth modes of CH4 hydrate and CO2 hydrate under static conditions and believed that the wall-climbing growth mode of CH4 hydrate can be used to generate CO2 hydrate. It is proposed to use the residual shell of CH4 hydrate as a water-absorbing medium to change the mode in which CO2 hydrate is preferentially generated in the main body of the liquid phase. In this method, CO2 hydrate shows a faster formation rate and almost no induction time, which is attributed to the larger gas-liquid contact area provided by the shell, the residual ring in decomposed water on the surface, and the crystal structure inside the shell. When sodium dodecanoate (SD) is used as a promotor for CH4 hydrate to regenerate CO2 hydrate, the observation of the hydrate growth morphology shows that CO2 hydrate can grow on the CH4 hydrate shell. It does not have the wall climbing height of CH4 hydrate but grows toward the center of the reactor. When SDS is combined with SD to regenerate CO2 hydrate as an accelerator in the CH4 hydrate generation process, filamentous growth of CO2 hydrate can be observed.

Gas solubility enhancement and hydrogen bond recombination regulated by terahertz electromagnetic field for rapid formation of gas hydrates

The low solubility of methane in water and the formation of hydrate film at methane-water interface restrict interfacial mass transfer between methane and water, thereby impeding the rapid formation of hydrate. Herein, THz electromagnetic field (TEMF) is introduced to destroy hydrogen bonds through resonance with water molecules for decreasing methane-water interfacial tension (IFT) and improving methane solubility in water. Thereafter, TEMF is removed to restore hydrogen bonding interaction for hydrate nucleation within bulk-phase water rather than at methane-water interface, thereby accelerating hydrate formation. The results show that a TEMF at 15.8 THz can increase methane solubility by 50-fold and provide more nucleation sites for hydrate formation by lowering the IFT by 15-fold. Furthermore, the hydrate nucleation follows “blob” nucleation at low solubility and Local Structuring Mechanism nucleation at high solubility. The higher solubility of methane shortens the induction period of hydrate nucleation form 58.5 ns to 29 ns. Particularly, small 512 cages form preferentially regardless of nucleation pathway. The underlying mechanism for TEMF-induced the acceleration of hydrate formation is attributed to the transition of water phase from a disordered to an ordered structure. This transition arises from the resonance of the TEMF with water molecules, disrupting the hydrogen bond between water molecules and providing sufficient driving force for their rearrangement after removing the TEMF. In rearrangement process, weakly hydrogen-bond interactions correspondingly are converted into strongly hydrogen-bond ones. These findings are expected to improve the understanding of hydrate formation mechanism and promote the applications of terahertz technology in gas hydrates.

Experimental study on the cold-seep methane hydrate formation kinetics

Cold-seep methane hydrates are widespread in the natural environment. A comprehensive understanding of the cold-seep methane hydrate formation kinetics is crucial for the knowledge of formation mechanisms and the development and utilization of natural gas hydrate. This study monitored the kinetics of methane hydrate formation in cold-seep fluids using continuous time-series Raman spectroscopy. A novel spectroscopic method was proposed to accurately determine the nucleation time of gas hydrates with a ten-second accuracy. Experimental results showed a smooth transition from dissolved methane to hydrated methane. Rapid hydrate nucleation and growth initiation were observed at the gas–liquid interface, forming hydrate films wrapping gas bubbles and suspending hydrate microcrystals in cold-seep fluids. Furthermore, a model for cold-seep methane hydrate formation kinetics was proposed, which indicated three distinct stages including an induction period, a metastable nucleation period, and a stable growth period.

Pore-scale visualization of hydrate dissociation and mass transfer during depressurization using microfluidic experiments

Natural gas hydrate is a potential low-carbon energy resource. Extracting this resource efficiently remains a challenge, due to the intricacies involved in multiphase reactive transport during hydrate dissociation. This study employs microfluidic experimental techniques to observe pore-scale interactions during depressurization-induced hydrate dissociation, utilizing high-resolution spatial and temporal imagery. Supervised machine learning algorithms segmented these microscopic images, enabling the analysis of phase saturation changes and hydrate dissociation rates. The study identifies two distinct hydrate forms in microfluidic chips: hydrate films and crystals, each exhibiting unique dissociation characteristics. Hydrate films decomposed rapidly in response to pressure reductions below equilibrium with the dissociation rate of O(10−1 %/s) under stationary gas–water conditions. When considering gas–water migration, the gas encapsulated in the hydrate film will be displaced by water, leading to a reduced dissociation rate. The hydrate crystal dissociation is much slower with the dissociation rate of O(10−3 %/s) under stationary gas–water conditions compared to the hydrate film, hindered by mass transfer limitations. Gas-water migration can enhance crystal dissociation. The formation and expansion of gas microbubbles under depressurization accelerated hydrate dissociation within a confined temporal and spatial range, which was known as the self-promotion mechanisms. Significantly, depressurization-induced gas slug flow increases the dissociation rate by more than one order of magnitude, compared to that in stationary gas–water conditions. The depressurization process played a significant role, not only by facilitating thermodynamic feasibility for hydrate dissociation but also by inducing the critical gas slug flow. These results of the present study provide theoretical guidance for improving natural gas hydrate production efficiency.

Experimental study of adsorption/desorption and enhanced recovery of shale oil and gas by zwitterionic surfactants

Shale reservoirs have the characteristics of low permeability and low porosity. In order to enhance the recovery of shale oil and gas, surfactant flooding is a mature reservoir oil recovery method. However, the adsorption of different surfactants on the reservoir rock surface is restricted, depending on the type of surfactant. Therefore, a zwitterionic surfactant (OPHS) was synthesized from oleic acid, 3-dimethylaminopropylamine and sodium 3-chloro-2hydroxypropanesulfonate, and characterized by FTIR, 1H NMR, and TGA, and the mechanism of the OPHS for enhancing oil and gas recovery on shale surfaces was investigated. The results showed that the critical micelle concentration (CMC) of OPHS surfactant solution is 7.9 × 10-4 mol/L and the γCMC is 27.5 mN/m; the concentration of 0.1 % OPHS surfactant solution could reduce the contact angle of the cores from 127.2° to 38.8°, which resulted in spontaneous imbibition; The absolute Zeta potential of shale particles in the OPHS surfactant solution was measured at 39 mV, whereas in deionized water at 15.3 mV. This difference can be attributed to the formation of a stable hydration film on the surface of shale particles induced by the wetting reversal effect. Spontaneous imbibition experiments showed that a 0.1 % solution of OPHS surfactant was able to increase the recovery rate by more than four times compared to the imbibition solution without added surfactant; In high-pressure gas adsorption/desorption experiments, the OPHS surfactant solution demonstrated a higher affinity for adsorption onto the shale surface. It effectively occupied adsorption sites, ultimately facilitating methane gas desorption from the shale. In summary, OPHS zwitterionic surfactants exhibit the capability to desorb hydrocarbons from shale pores through mechanisms such as wetting reversal and competitive adsorption. This research holds significant potential for advancing the field of shale oil and gas recovery, providing valuable insights for enhancing recovery processes.

Study of Sintering Behavior of Methane Hydrate Particles on the Wall Surface.

The sintering of hydrate aggregates on the pipe wall is a major form of hydrate deposition. Understanding the sintering behavior of hydrates on the wall is crucial for promoting hydrate safety management and preventing pipeline blockage. However, limited research currently exists on this topic. In this study, the cohesive force strength of hydrate particles on the wall surface under different conditions was directly measured using a high-pressure micromechanical force device (HP-MMF). Subsequently, the effects of subcooling and glycine on the cohesive force were investigated. The results indicate that the cohesive force is influenced by different growth states during the process of free water on the wall surface gradually growing into hydrate. Three states with larger measured values during the growth process were selected for research. Observation showed that increased subcooling strengthened sintering by accelerating the growth rate of the hydrate film, resulting in a significant increase in cohesive force. The role of glycine in the methane hydrate system was then evaluated. Glycine was found to reduce the degree of sintering by reducing the growth rate of the hydrate film, thereby decreasing the cohesive force. The optimal concentration in the system was determined to be 0.25 wt %. Moreover, compared with low subcooling (1 °C), glycine had a better effect at high subcooling (5 °C). At 5 °C subcooling and the optimal concentration, the cohesive force in the wall droplet state decreases from 677.38 to 489.02 mN/m, the cohesive force at the low-saturation state decreases from 951.79 to 543.32 mN/m, and the cohesive force at the high-saturation state decreases from 1194.95 to 641.76 mN/m. These findings contribute to a better understanding of the cohesive force behavior of gas hydrate on the inner wall of the pipeline and provide basic data for reducing the risk of hydrate blockage.

Demystifying Fogging in Lyophilized Products: Impact of Pharmaceutical Processing

A commonly encountered challenge with freeze-dried drug products is glass vial fogging. Fogging is characterized by a thin layer of product deposited upon the inner surface of the vial above the lyophilized cake. While considered to be a routine cosmetic defect in many instances, fogging around the shoulder and neck of the vial may potentially impact container closure integrity and reject rates during inspection. In this work, the influence of processing conditions i.e. vial pre-treatment, lyophilization cycle modifications and filling conditions on fogging was evaluated. A battery of analytical techniques was employed to investigate factors affecting glass vial fogging. A fogging score was used to quantify its severity in freeze-dried products. Additionally, a dye-based method was used to study solution upcreep (Marangoni flow) following product filling. Our lab-scale results indicate measurable improvement in fogging following the addition of an annealing step in the lyophilization cycle. Pre-freeze isothermal holding of the vials (at 5°C on the lyophilizer shelf) for an extended duration indicated a reduction in fogging whereas an increase in the freezing time exhibited no effect on fogging. Vial pre-treatment conditions were critical determinants of fogging for Type 1 vials whereas they had no impact on fogging in TopLyo® vials. The headspace relative humidity (RH) investigation also indicated sufficient increase in the water vapor pressure inside the vial to be conducive to the formulation of a hydration film - the precursor to Marangoni flow.

Black phosphorus boosts wet-tissue adhesion of composite patches by enhancing water absorption and mechanical properties

Wet-tissue adhesives have long been attractive materials for realizing complicated biomedical functions. However, the hydration film on wet tissues can generate a boundary, forming hydrogen bonds with the adhesives that weaken adhesive strength. Introducing black phosphorus (BP) is believed to enhance the water absorption capacity of tape-type adhesives and effectively eliminate hydration layers between the tissue and adhesive. This study reports a composite patch integrated with BP nanosheets (CPB) for wet-tissue adhesion. The patch’s improved water absorption and mechanical properties ensure its immediate and robust adhesion to wet tissues. Various bioapplications of CPB are demonstrated, such as rapid hemostasis (within ~1-2 seconds), monitoring of physical-activity and prevention of tumour-recurrence, all validated via in vivo studies. Given the good practicability, histocompatibility and biodegradability of CPB, the proposed patches hold significant promise for a wide range of biomedical applications.

Adsorption and accumulation of N2 at the solid–liquid interface: The impact of hydration films

The adsorption and accumulation of gases at the solid–liquid interface facilitate the formation of nanobubbles, offering significant benefits to the separation of fine mineral particles in flotation processes. In this study, a synergy of experimental and molecular simulation (MD) simulations was employed to elucidate the effects of mineral surface hydration film characteristics on the behavior of gas adsorption and accumulation in aqueous environment. The research findings indicate that, in comparison to hydrophobic graphite, there is an improvement in both the thickness and stability of the surface hydration film subsequent to the oxidation of graphite. After graphite oxidation, the difficulty of gas adsorption, accumulation, and the formation of nanobubbles in aqueous environments increases, with only a limited number of nanobubbles tending to accumulate within the hydrophobic regions of the oxidized graphite surface. MD simulations reveal that, despite N2 molecules primarily experiencing Van der Waals forces on methylated-substrate and carboxylated-substrate, the difference in their adsorption strength is relatively minor. However, the substantial contrast in H2O molecule adsorption on methylated-substrate and carboxylated-substrate prevents N2 molecules from penetrating the hydrophilic carboxylated-substrate's pre-adsorbed water layer, whereas adsorption and accumulation of N2 molecules occur on the hydrophobic methylated-substrate surface.