Liquid Separation Research Articles

Transient behavior of the DYNASWIRL® phase separator during cryogenics tank-to-tank transfer operations

In order to separate gas and liquid from a two-phase mixture in space or earth applications, one can generate a strong artificial acceleration field instead of relying on gravity. This can be achieved by generating a swirl flow in a separator. The DYNASWIRL® phase separator is such a passive device, which had been demonstrated in air/water mixtures in the laboratory and on five reduced gravity NASA parabolic flights. In this work, extensive laboratory testing and numerical simulations are conducted to demonstrate the validity of the DYNASWIRL for phase separation with cryogenics. Liquid nitrogen (LN2) is used for extensive testing involving unsteady tank-to-tank transfer with quenching of separator and piping, liquid boil-off and vaporization, phase separation and recovery. This paper describes the separator and testing setups used. It examines the effects of the liquid (water and LN2), geometric parameters, and their effects on the separation and on the pressure loss across the separator, and analyzes the flow dynamics of the gas removal process. Validated numerical simulations support the experimental results and help explain the effects of the design parameters on the results.

Process Intensification of Gas–Liquid Separations Using Packed Beds: A Review

The gas–liquid multiphase process plays a crucial role in the chemical industry, and the utilization of packed beds enhances separation efficiency by increasing the contact area and promoting effective gas–liquid interaction during the separation process. This paper primarily reviews the progress from fundamental research to practical application of gas–liquid multiphase processes in packed bed reactors, focusing on advancements in fluid mechanics (flow patterns, liquid holdup, and pressure drop) and the mechanisms governing gas–liquid interactions within these reactors. Firstly, we present an overview of recent developments in understanding gas–liquid flow patterns; subsequently we summarize liquid holdup and pressure drop characteristics within packed beds. Furthermore, we analyze the underlying mechanisms involved in bubble breakup and coalescence phenomena occurring during continuous flow of gas–liquid dispersions, providing insights for reactor design and operation strategies. Finally, we summarize applications of packed bed reactors in carbon dioxide absorption, chemical reactions, and wastewater treatment while offering future perspectives. These findings serve as valuable references for optimizing gas–liquid separation processes.

Recent Research Progress of Porous Graphene and Applications in Molecular Sieve, Sensor, and Supercapacitor.

Porous graphene, including 2D and 3D porous graphene, is widely researched recently. One of the most attractive features is the proper utilization of graphene defects, which combine the advantages of both graphene and porous materials, greatly enriching the applications of porous graphene in biology, chemistry, electronics, and other fields. In this review, the defects of graphene are first discussed to provide a comprehensive understanding of porous graphene. Then, the latest advancements in the preparation of 2D and 3D porous graphene are presented. The pros and cons of these preparation methods are discussed in detail, providing a direction for the fabrication of porous graphene. Moreover, various superior properties of porous graphene are described, laying the foundation for their promising applications. Owing to its abundant morphology, wide distribution of pore size, and remarkable properties benefited from porous structure, porous graphene can not only promote molecular diffusion and electron transfer but also expose more active sites. Consequently, a serious of applications containing gas sieving, liquid separation, sensors, and supercapacitors, are presented. Finally, the challenges confronted during preparation and characterization of porous graphene are discussed, offering guidance for the future development of porous graphene in fabrication, characterization, properties, and applications.

Zinc-imidazole-based metal-organic framework nanosheet membrane for H2/O2 separation

Abstract Metal-organic framework (MOF) nanosheets are promising candidates for molecular sieve because of their structural diversity and minimized mass transfer barrier. However, design of appropriate MOF nanosheets and preparation of high-performance MOF nanosheet-based membranes, especially for gas separation, remains great challenges. Structural degradation may simultaneously occur with conventional exfoliation method, which has hindered its widespread application in high-performance molecular sieve membrane preparation. Even if nanosheets could be stacked, grain boundaries would form between the nanosheets, which could be applied to liquid separation but not to gas separation. To address these challenges, we applied bottom-up growth of Zn2(benzimidazole)4 nanosheet to fabricate defect-free membranes. Zn2(benzimidazole)4 is composed of benzimidazole-zinc tetrahedral units and layers are connected by van der Waals interaction. At first, the Zn2(benzimidazole)4 nanosheets were deposited onto a porous support to prepare gutter layer. Next, Zn-based amorphous layer was coated on the gutter layer and crystallized by benzimidazole vapor treatment. Highly oriented Zn2(benzimidazole)4 nanosheet based membranes were fabricated by anisotropically controlling crystallization. The prepared Zn2(benzimidazole)4 nanosheet-based membranes show separation performance in hydrogen purification with H2/O2 ideal separation factor of 11.6 and H2 permeance of 5650 GPU.

Numerical investigation of dynamic gas–liquid separator by population balance model

Dynamic gas–liquid separator (DGLS) can efficiently separate gas and liquid phases and are widely used in aerospace, chemical, and petroleum engineering. The energy loss and separation efficiency within the DGLS are studied through the combination of numerical simulations and experiments. Three-dimensional transient Reynolds-Averaged Navier–Stokes equations were solved to analyze the fluid dynamics within the DGLS. The bubble aggregation and breakup in oil were simulated by using the population balance model. Experimental data were meticulously compared with numerical results to validate the accuracy and reliability of the numerical methods. The findings revealed a direct correlation between the inlet flow rate and various performance metrics of the DGLS. Specifically, as the inlet flow rate increased, the energy loss within the DGLS escalated, resulting in higher power consumption. The degassing rate of the DGLS exhibited a decreasing trend with increasing inlet flow rate, while the de-oiling rate showed an inverse relationship. The optimal performance of the separator was observed at an inlet flow rate of 140 m3·d−1, with ηg* and ηl* reaching 0.94 and 0.99, respectively. The relationship between the Qo and the η* and Po was fitted by a second-order polynomial. Moreover, the rotational speed of the DGLS demonstrated a positive correlation with energy consumption, accompanied by an increase in power output. However, the separation efficiency of the DGLS exhibited a non-linear relationship with rotational speed, peaking at a specific value before marginally declining. The optimization of degassing and dewatering rates occurred at a rotational speed of 2500 r·min−1. These findings underscore the importance of carefully adjusting operational parameters to achieve optimal performance and energy efficiency within DGLS.

From enzyme dispersion to purification: Optimizing biocatalytic membranes for high-purity ginsenoside Rd production

This study presents a novel biocatalytic membrane (BM) system for the continuous production of high-purity ginsenoside Rd. Recognizing that enzymes concentrated on one side of BM caused by reverse filtration hinder substrate access and catalytic efficiency, polyethyleneimine (PEI) and polyallylamine hydrochloride (PAH) were added during dopamine (DA) deposition. They effectively disrupted the clustering of enzyme molecules, enabling a more homogeneous enzyme distribution within BMs, as confirmed by microscopy, activity assays, and simulations. This controlled dispersion, facilitated by Protein-Polyelectrolyte Complexes (PPCs) formation, significantly improved substrate accessibility and catalytic performance. Exceptional catalytic performance was exhibited by the optimized PDA/PEI BM (using 1800 Da PEI), enabling highly efficient conversion of Rb1 to Rd. This high conversion efficiency, coupled with the inherent temperature-dependent solubility of Rd, enables a remarkably simple purification process. By exploiting Rd precipitation upon cooling, high-purity (93.1 %) Rd was achieved at a 55.6 % recovery from a 70 % purity Rb1 feed using a simple solid–liquid separation, eliminating the need for other separation techniques. This study provides new insights into the preparation of BMs and offers innovative strategies for the transformation and purification of ginsenosides.

Geochemical characterization and reserve estimation of the economic heavy minerals of Sonadia Island, Bangladesh

The goal of the current study is to understand the elemental concentration, reserve assessment, mineralogical composition, and distribution of heavy minerals in the dune sands, foreshore, and backshore of Sonadia Island, Southeast Bangladesh. The study area yielded a number of drill hole composite sand samples that were used for density and magnetic separation of heavy minerals. These samples were then subjected to petrographic characterization, grain counting, mineralogical analyses using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX), x-ray diffraction (XRD), and bulk sand geochemistry using X-ray fluorescence (XRF). The results of heavy liquid separation show that the total heavy mineral (THM) enrichments in foreshore sand (about 4.86%), backshore sand (about 9.03%), and dune sand (about 22.28%) are significantly higher. After characterizing the sand samples from Sonadia Island based on the abundance of each mineral species, the average content values relative to total economic heavy minerals (TEHM) were determined to be 38.14% ilmenite, 5.74% magnetite, 51.52% garnet, 1.01% zircon, 3.57% rutile, and 0.01% monazite. An SEM–EDX examination reveals that the elemental concentration of ZrO2 in zircon is 66.60%, while the average TiO2 content in rutile is ~ 95%, whereas TiO2 is 45% and the total Fe2O3 is 45.70% in ilmenite. Major phases including amphibole (tremolite) 45.9%, muscovite 15.6%, quartz 12.6%, garnet (almandine) 10.9%, dolomite 7.9%, ilmenite 4.1%, and kaolinite 1.3% are also identified by the XRD pattern. There are an estimated 19,794 tons of garnet in the foreshore sand, 47,324 tons in the backshore sand, and 276,868 tons in the dune sand within the reserve, making it the most prevalent heavy mineral. Ilmenite is the second most common heavy mineral, with quantities detected in the foreshore (15,016 tons), backshore (30,487 tons), and dune sand (215,092 tons).

Enhanced Phase Change Heat Transfer with Fused Deposition Modeling (FDM) Printed Pit and Pillar (Pi2) Arrays

Phase change heat transfer, crucial in thermal management systems, can be significantly enhanced through optimized surface structures. This study investigates pool boiling heat transfer enhancement using 3D printed structures with carefully designed pillar and pit geometries. We present a novel approach combining the Dual Rise model with separate liquid–vapor pathways to improve Critical Heat Flux (CHF) and Heat Transfer Coefficients (HTC). Using copper-infused Polylactic Acid (PLA) filaments, we created and sintered structured surfaces featuring pit-assisted nucleation sites, interpillar spacing for vapor escape, and pillar roughness for enhanced liquid supply. Experiments with deionized water and ethanol under atmospheric pressure demonstrated substantial improvements over plain surfaces: water showed an 87% increase in CHF and 39% in maximum HTC, while ethanol exhibited even greater enhancements of 122% in CHF and 61% in HTC. These improvements are attributed to the synergistic effects of optimized surface geometry and separated liquid–vapor pathways, reducing counterflow resistance and improving hydrodynamic stability. A theoretical framework based on the Dual Rise model explains these enhancements, providing insights into coupled capillary action and hemiwicking effects in boiling heat transfer. The study introduces predictive models for CHF and HTC enhancement, offering valuable tools for future design optimization in applications ranging from electronics cooling to power plant thermal management and advanced heat exchangers.

Amphiphilic Ionic Liquids for Chemical Separation of Crude Oil Emulsions

AbstractThis work aims to synthesize novel amphiphilic ionic liquids (AILs), AH‐PM, and AD‐PM as well as apply them to chemically demulsifying crude oil emulsions. Two AILs containing different long alkyl chains were synthesized and characterized using several techniques. The surface and interfacial indicated AILs’ surface activity and ability to form micelles. For that, the demulsification efficacy (DE) of these AILs was explored using different factors affecting, e.g., AIL dose, settling time (ST), water content, and temperature. The results indicated that the AIL hydrophobicity resulting from the longer alkyl chain could improve AIL DE. Moreover, increased AIL dose, ST, water content, and temperature improved DE.

Cooling Rate and Compositional Effects on Microstructural Evolution and Mechanical Properties of (CoCrCuTi)100-xFex High-Entropy Alloys.

This study investigates the impact of cooling rate and alloy composition on phase formations and properties of (CoCrCuTi)100-xFex (x = 0, 5, 10, 12.5, 15) high-entropy alloys (HEAs). Samples were synthesized using arc-melting and electromagnetic levitation, followed by quenching through the use of a Cu chill or V-shaped Cu mold. Cooling rates were evaluated by measuring dendrite arm spacings (DASs), employing the relation DAS = k ɛ-n, where constants k = 16 and n = ½. Without Fe addition, a microstructure consisting of BCC1 + BCC2 phases formed, along with an interdendritic (ID) FCC Cu-rich phase. However, with the addition of 5-10% Fe, a Cu-lean C14 Laves phase emerged, accompanied by a Cu-rich ID FCC phase. For cooling rates below 75 K/s, alloys containing 10% Fe exhibited liquid phase separation (LPS), characterized by globular Cu-rich structures within the Cu-lean liquid. In contrast, for the same composition, higher cooling rates of 400-700 K/s promoted a dendritic/interdendritic microstructure. Alloys with 12.5-15 at. % Fe displayed LPS irrespective of the cooling rate, although an increase in uniformity was noted at rates exceeding 700 K/s. Vickers hardness and fracture toughness generally increased with Fe content, with hardness ranging from 444 to 891 HV. The highest fracture toughness (5.5 ± 0.4 KIC) and hardness (891 ± 66 HV) were achieved in samples containing 15 at. % Fe, cooled at rates of 25-75 K/s.

Evaluation of a simultaneous approach to concentrate and preserve bioactive compounds with distinct polarities by employing supramolecular solvents (SUPRAS)

Supramolecular solvents (SUPRAS) have attracted attention as eco-friendly and highly effective solvents that can be tailored to solubilize compounds with distinct polarities. This study investigated the SUPRAS/equilibrium solution systems’ (SUPRAS-EqS) capacity to concentrate and preserve bioactive compounds through simultaneous solvent production and a liquid–liquid separation method. For this, β-carotene, quercetin, and curcumin were evaluated as molecular probes. SUPRAS-EqS systems were produced with octanoic acid (5 %, v/v), ethanol (20–––35 %, v/v), and acidified water (75–––60 %, v/v) and characterized concerning SUPRAS phase formation and their composition. Moreover, the SUPRAS phase’s ability to preserve these compounds during thermal exposure was evaluated at 313.15 K, 323.15 K, and 333.15 K and compared with an ethanolic medium. The outcomes demonstrated the formation of spherical supramolecular aggregates (10 to 20 μm), where the size of coacervates increased proportionally with the ethanol concentration. Concerning the separation efficiency provided by the SUPRAS phase, all compounds exhibited values superior to 83 %, and the systems produced with 22.5 % ethanol for quercetin and curcumin, and 27.5 % ethanol for β-carotene, presented the highest partition coefficient values. The SUPRAS phase promoted a more suitable environment to preserve the bioactive compounds than ethanol, and quercetin exhibited the highest half-life time values. Curcumin displayed the strongest activation energy in both the SUPRAS phase (48.88 kJ/mol) and the ethanol media (54.50 kJ/mol), indicating its high temperature dependence compared to the other compounds. These findings highlight the SUPRAS phase capacity to concentrate and stabilize bioactive compounds individually with different polarities.

Re-entrant phase transitions in Laponite/Gum Arabic nanocomposites

A re-entrant gel transition is observed in a discotic clay, Laponite (Lap) aqueous suspensions with the addition of a complex polysaccharide, Gum Arabic (GA). For fixed concentrations of Lap (1–3 % w/v) and at low GA concentrations (CGA < 10 % w/v), the composites exhibit gel behaviour, while the suspensions undergo liquid phase separation for intermediate GA concentrations (10 % w/v < CGA < 20 % w/v). Gel behaviour is again observed in the samples at even higher GA concentrations (CGA > 30 % w/v). Here, we identify a thermodynamic phase transition in Lap/GA mixtures that is caused by a variation in GA content. The viscoelastic characteristics, phase transitions, and gelation kinetics of the Lap/GA mixtures have been studied by employing rheology, small-angle X-ray scattering, and optical investigations. Reduction of the negative values of zeta-potential and growth of the composite system's hydrodynamic size indicated the presence of interactions in Lap/GA mixtures. The phase diagram enables the apparent interactions and phase transitions between the nanoplatelets and the complex polysaccharides. Thus, our study provides new perspectives on a nanocomposite's tuneable rheological and structural features.

Effects of water salinity and temperature on oil-in-water emulsions stabilized by a nonionic surfactant

The goal of this work is to understand the effect of water salinity of three salts- NaCl, CaCl2, and MgCl2- on oil-in-water (O/W) emulsions stabilized by nonionic surfactants such as Tergitol 15-S-7 (T15S7). The study investigates not only the impacts of mixing speed, water salinity, and temperature but also the combined effects of salt and temperature on emulsion stability. All emulsions were created using ExxsolTM D110 and distilled water, with a surfactant concentration of 0.050 % wt. in the water phase. Two oil fractions (10 % and 25 % by volume) were studied, and oil and water separation interfaces were measured using a state-of-the-art apparatus, which can record and scan videos of free liquid separation. According to the experimental findings, at concentrations higher than the surfactant’s Critical Micelle Concentration (CMC), neither of the divalent salts affects the surface tension of the aqueous solution. Divalent ions, on the other hand, were found to decrease the surfactant’s effectiveness at concentrations lower than the CMC. Conversely, monovalent ions had no effect at low concentrations but further reduced the surface tension at large concentrations. All salts, however, had no effect on the volume of the emulsion for more than 4 h at 25 °C, however at 70 °C, 100 % separation happens in a matter of seconds. Decrease in mixing speed from 2500 RPM to 800 RPM caused the emulsion volume to decrease by at least 72 %.

Kinetics and dynamics of Gas-liquid separation and bubble generation in surfactant solutions: Role of bulk/interfacial properties and hydrodynamic conditions

Understanding the kinetics and dynamics of gas–liquid separation and bubble generation in surfactant solutions is important for many industrial applications. To explore the potential mechanisms affecting the physical properties (expansion ratio, bubble size, and foam stability) of foams and bubbles, the surface tension of the solution, including the equilibrium and dynamic properties, was investigated. Then, the morphology of the surfactant aggregates was explored by cryo-transmission electron microscopy (cryo-TEM). Based on these experimental results, the effects of various physical and chemical factors (including the relative concentration of surfactant, dynamic surface tension, surface coverage, surface elasticity, surface mobility, aggregate morphology, etc.) on the expansion ratio and bubble size were analysed to identify which “universal” parameters can explain the phenomenon for all aqueous solutions in the gas–liquid separation process. Research has shown that the morphology of aggregates in a solution largely determines the surface properties of the solution at 1.5 ms (surface tension, surface coverage, surface elasticity, and so on). These surface properties significantly affect the expansion ratio. However, no good correlation was found between bubble size and these surface properties because surfactant vesicles can directly affect bubble size. In addition, the liquid flow rate and gas–liquid ratio have a significant impact on the expansion ratio and bubble size. Ultimately, we found that the foam stability, bubble size, and expansion ration can be described by a simple linear relationship. Our research provides new opinions for further understanding the effects of bulk/interfacial properties and hydrodynamic conditions on the physical properties of bubbles in the gas–liquid separation process.

Liquid-liquid equilibrium of binary ethanol–polyisobutene and ternary ethanol–water–polyisobutene systems under low- and high-pressure conditions: An assessment using the PC-SAFT equation of state

Sugarcane bioethanol in either anhydrous or hydrous forms stands out as an economically viable bioproduct that can be used as a fuel or feedstock in various innovative applications, reducing human-generated greenhouse gas emissions. Low-molar-mass polyisobutene (PiB) is used as a lubricant in sugarcane-processing plants and is a possible contaminant of sugarcane bioethanol. Understanding the liquid–liquid equilibrium (LLE) of ethanol–PiB binary systems and ethanol–water–PiB ternary systems is essential to avoid undesired phase separation at high-pressure engine conditions and other potential innovative applications. However, the experimental investigation of these systems is significantly hampered by very low polymer solubilities in aqueous ethanol. The LLE of ethanol-PiB and ethanol–water–PiB mixtures was qualitatively investigated using the PC-SAFT equation of state through the development and implementation of extrapolation strategies allowing to estimate ethanol–PiB and water–PiB binary parameters using experimental data obtained for other systems containing lighter alkanes. Phase diagrams were calculated considering temperatures ranging from 298.15 K to 350 K and pressures ranging from 1 bar to 200 bar. It was shown that lower pressures, higher temperatures, lower PiB molar masses, and lower water contents increase the polymer solubility in the solvents. Thus, the risk of liquid–liquid separation can be mitigated by correctly managing such operational parameters. The obtained phase diagrams may present significant quantitative deviations from reality because of the model’s sensitivity to the estimated binary parameters. Thus, they should be interpreted as general qualitative guidelines to avoid and manage undesired phase separation in industrial processes and engines rather than phase equilibrium predictions.

Application of Ionic Liquids in Environmental and Food Fields

Abstract: As a new type of green solvent, ionic liquids have made rapid progress in the fields of organic synthesis, separation, and electrochemistry due to their unique physical and chemical properties. At the same time, the new fluorescence characteristics and good separation and adsorption functions of ionic liquids have gradually developed in the field of environment and food, showing a good application prospect. Based on the work of our research group and the progress and development of research technology, this article reviews the research results of ionic liquids in environmental monitoring and food detection and extraction in recent years. In the environmental field, ionic liquids have the ability of detection and remediation and they show the advantages of fast, efficient, green and recyclable in the detection of environmental pollutants. In the field of food, ionic liquids provide a new idea for the detection and extraction technology of food components. While ensuring green, safe and pollution-free, they show superior selectivity, repeatability and stability, and simplify the operation steps and costs to a certain extent, showing the capture vitality with life characteristics. As a potential smart material, the mechanism of ionic liquids as fluorescent probes and separation extractants was discussed. Finally, the future development and research directions of ionic liquids are prospected, and it is expected to realize the intelligentization of ionic liquid materials and the general integration of development.

Advancements in Biopolymer‐Derived Graft Copolymers: A Comprehensive Review on Their Application in Sustainable Wastewater Treatment

ABSTRACTRising concerns over water pollution and the depletion of non‐renewable resources have propelled the exploration of eco‐friendly and sustainable wastewater treatment alternatives. Biopolymer‐derived graft copolymers emerge as a promising solution, offering biodegradability, cost‐effectiveness, versatility, and enhanced functionality. This review provides a comprehensive overview of the latest developments in utilizing these copolymers as eco‐friendly flocculants for wastewater treatment. It covers synthesis methods for functionalized biopolymer‐based flocculants, diverse flocculation mechanisms, and their efficacy in solid–liquid separation. The article explores applications for removing pollutants, emphasizing biodegradability, cost‐effectiveness, and versatility. Special attention is given to the environmental impact, critically analyzing how these copolymers contribute to sustainable water treatment practices. The review also discusses potential future prospects and advancements in addressing global water pollution challenges using biopolymer‐derived graft copolymers.

Sterol–lipids enable large-scale, liquid–liquid phase separation in bilayer membranes of only two components

Despite longstanding excitement and progress toward understanding liquid-liquid phase separation in natural and artificial membranes, fundamental questions have persisted about which molecules are required for this phenomenon. Except in extraordinary circumstances, the smallest number of components that has produced large-scale, liquid-liquid phase separation in bilayers has stubbornly remained at three: a sterol, a phospholipid with ordered chains, and a phospholipid with disordered chains. This requirement of three components is puzzling because only two components are required for liquid-liquid phase separation in lipid monolayers, which resemble half of a bilayer. Inspired by reports that sterols interact closely with lipids with ordered chains, we tested whether phase separation would occur in bilayers in which a sterol and lipid were replaced by a single, joined sterol-lipid. By evaluating a panel of sterol-lipids, some of which are present in bacteria, we found a minimal bilayer of only two components (PChemsPC and diPhyPC) that robustly demixes into micron-scale, liquid phases. It suggests an additional role for sterol-lipids in nature, and it reveals a membrane in which tie-lines (and, therefore, the lipid composition of each phase) are straightforward to determine and will be consistent across multiple laboratories.

Computational fluid dynamics modeling of gas bubble separation efficiency in downhole separators and vertical / inclined annulus: An experimental validation and analysis

This study presents a comprehensive investigation into gas bubble separation efficiency in a vertical downhole separator using computational fluid dynamics (CFD) modeling, which is validated with experimental data. The research aims to provide detailed insights into the separation mechanisms and the factors affecting them, such as liquid velocity, gas bubble sizes, and positions. Using an Euler-Lagrange multiphase model, the behavior of individual gas bubbles within the liquid-gas mixture was simulated. The results demonstrate that separation efficiency decreases as the liquid flow rate increases. This reduction in efficiency occurs because the increased liquid flow rate drags more bubbles within the stream, making it harder for them to separate. The separation process is primarily driven by the buoyancy force acting on the bubbles and the velocity profile of the liquid flow. Smaller bubbles, which tend to be near the casing wall, separate more efficiently, while larger bubbles are predominantly located between the second and third quarters of the annulus space. The "quarters" refer to radial divisions from the casing wall to the tubing wall, with the first quarter closest to the casing wall and the fourth quarter closest to the tubing wall. The study introduces a nonlinear regression model based on the numerical results to predict liquid slug separation efficiency. This model, validated against experimental data, accurately predicts separation efficiency and offers a robust methodology for estimating the efficiency of gravity-driven gas-liquid separators. This methodology is crucial for refining separator design and improving the operational efficiency of downhole separation systems, which are vital for enhancing the performance of pumping systems in oil and gas wells. The contributions of this study include a deeper understanding of the downhole separation process, the development of a simplified model for assessing bubble separation efficiency, and the potential application of the proposed methodology to different gas-liquid separator designs and inclination angles, thereby informing the design and operation of downhole separation systems.

A simple and efficient approach for pore structure optimization and hydrophilic modification of PTFE nanofiber membrane

Polytetrafluoroethylene (PTFE) membranes have great potential for treating wastewater in harsh environment due to their excellent stability. However, difficulties in the pore structure optimization and functional modification of biaxial stretched PTFE membrane have limited its further applications in liquid separation. Herein, we presented a simple and efficient approach for the preparation and hydrophilic modification of electrospun PTFE nanofiber membranes. This method involved optimizing the pore structure of PTFE nanofiber membranes through adjusting the mass ratio of the spinning carrier polyethylene oxide (PEO) and PTFE, followed by introducing the acetalized polyvinyl alcohol (PVA) on the membrane’s pore surface to improve the hydrophilicity. The average pore size changed from 288.5 to 161.3 nm, while the water contact angle reduced from 135.7° to 50.9°, which not only increased the water permeate flux from 68.56 to 1056.16 L·m−2·h−1, but also achieved high rejection rates of 99.3 % and 97.3 % for carbon (1 μm) and SiO2 (100 nm) particles respectively. Meanwhile, the obtained PTFE nanofiber membrane also exhibited excellent hydrophilic stability after long term exposure to harsh environments (pH=2 HCl, pH=12 NaOH, 1000 ppm NaClO) and 100 friction cycles (5 g weights on 1000 mesh sandpaper). This approach of preparing hydrophilic PTFE nanofiber membranes showed significant potential for practical applications in wastewater treatment.