Efficient Demulsification Research Articles

Enhancing the efficiency of novel PCNF demulsifier for oil-contaminated wastewater treatment through numerical simulation optimization of demulsification mechanism

This study used COMSOL simulation software to simulate the aggregation behavior of oil droplets under the action of a direct current electric field. Moreover, in-depth research was conducted on the aggregation process of oil droplets and the dynamic changes of the water oil micro interface. Research has found that the interfacial tension between water and oil is an important factor affecting the deformation of oil droplets. In this work, a new type of magnetic demulsifier (PCNF) was prepared using nano-Fe3O4 as the condensed core, sodium carboxymethyl cellulose (CMC-Na) as the binder, and polyferric sulfate (PFS), and this demulsifier was coupled with an electroflocculation process. The results indicate that the addition of PCNF can effectively reduce the interfacial tension between water and oil, promoting the demulsification process. Compared with traditional flocculants, the combination of electrochemical action and the optimal 2 g/L PCNF dosage provides higher purification efficiency. By introducing calcium chloride, the dosage of PCNF can be reduced. When the dosage is adjusted to 1.5 g PCNF + 0.5 g calcium chloride, the electrolysis time can be shortened from 180 min to 90 min. Under these treatment conditions, the COD in the emulsified oil wastewater is reduced to 46 mg/L and the oil content is reduced to 5.08 mg/L. Economic calculations show that compared to using PCNF alone, this reduction method can reduce operating costs by 39.83 %. This strategy achieves efficient demulsification and oil removal, lowers economic costs, and provides a solid foundation for guiding the development of practical technology.

In-situ thermally induced formation of an ultra-glossy hydrophilic surface for oil fouling prevention in TiO2@MXene membranes

Oil droplets are inevitably deposited on the surface of membranes, resulting in membrane contamination during oily sewage separation. To effectively prevent oil fouling, a TiO2@MXene membrane with an ultra-glossy hydrophilic surface was designed via in-situ thermal induction to regulate the membrane surface structure and properties. Through high temperature-induced evolving the Ti valence and the functional groups of Ti3C2Tx, uniform TiO2 nanoparticles were generated in-situ on the Ti3C2Tx surface while altering the surface structure and properties, which considerably improved the hydrophilicity, underwater oleophobic properties, and surface finish of the membrane. Specifically, the TiO2@MXene membrane (MT600) exhibited a low water contact angle of 7.5° and a high underwater oil contact angle of 133.3°. Notably, the oil adhesion force of the membrane was as low as 0.0013 μN, outperforming most oil water separation membranes. Thus, the unique structure and surface properties endowed MT600 membrane with excellent oil retention (TOC removal efficiency of > 95 %) and antipollution ability (permeance decay rates of < 10 %) for oil-in-water emulsion separation. This is because the ultra-glossy hydrophilic and oleophobic surface prompted the formation of a continuous and stable hydration layer on the membrane surface and prevented oil droplets from falling into the membrane grooves. Benefiting from the robust, ultra-glossy surface, the MT600 membrane exhibited excellent long-term durability and reusability (emulsion permeance recovery of > 90 %) in high-salt, highly acidic, and highly alkaline environments. This study opens pathways to realize ultra-glossy membrane surface for the efficient demulsification of small size emulsions and long-lasting, stable oil water separation.

Development of a demulsifier and technological process study for the preparation of highly viscous heavy oils for refinement

One of the challenges in the petroleum industry is the production of highly viscous heavy oils, often accompanied by undesirable emulsion formation with very high aggregate stability. To prepare the crude oils for refinement, the oils must be destroyed. The destruction of aqueous emulsions containing highly viscous heavy oils is an intricate task owing to the comparatively small disparity in water and oil densities, as well as the high viscosity of the dispersive medium and its high content of mechanical impurities. The problem of the destruction of petroleum emulsions arises desperately during the desalination and dehydration of crude oils with a high content of emulsifiers (resins, asphalts, paraffin, etc.) The creation of a highly efficient demulsifier and the development of an optimal technological process for the preparation of highly emulsifying oils that are distinguished by the composition and quantity of emulsifiers of West Siberian oils, which are widely refined in Russia, are the ways to resolve this challenging and timely issue. This study focuses on the viscous heavy oil of the Verbliouje deposit in the Astrakhan region. It also explains the creation of an effective demulsifier for the destruction of petroleum emulsions characterized by a very high emulsifying power and the fundamental principles of the development of deep dehydration technology and desalination of such high-viscosity heavy oils.

Influence of resins, asphaltenes and petroleum acid interactions on water/model oil interfacial properties and emulsion stability

The presence of natural lipophilic emulsifiers, such as asphaltenes (A), resin (R) and petroleum acids (PA) in crude oil, plays a crucial role in stabilizing the W/O emulsions. This study primarily focuses on elucidating the influence of their interactions on the interfacial properties of the water/model oil system, as well as its emulsion stability. First, equilibrium interfacial tension (IFT), interfacial dilational modulus (IDM) and phase angle are measured. Then, emulsion stability experiments are performed. Finally, microscopic images of the emulsions were captured to evaluate droplet size and dispersity. Results show that the addition of petroleum acid to both asphaltene-only and resin-only system reduces IFT and dilational modulus, weakening the strength of the interfacial film. The inhibitory effect of petroleum acid on resins’ adsorption at the interface is more pronounced compared to asphaltenes’. A low proportion of resin and petroleum acid (A/R ≥ 5, A/PA ≥ 7) enhances emulsion stability by co-adsorbing with asphaltenes at the oil–water interface. Conversely, a high proportion of resin and petroleum acid leads to a decrease in IDM and emulsion stability. For asphaltene/petroleum acid–water system, when A/PA ≤ 5, the presence of petroleum acid decreases the droplet size but enhances droplet dispersion while decreasing emulsion stability. It can be inferred that the presence of petroleum acids contributes more to the formation rather than stabilization of emulsions. This work deepens insights into the emulsion behavior of natural surfactants, providing theoretical guidance for the formation of stable emulsions underground and efficient demulsification above ground.

Preparation of novel nanoparticle demulsifier and its demulsification for surfactant-stabilized crude oil emulison

The application of nanoparticle (NP) demulsifiers in processing the emulsified crude oil production fluid is of great significance for improving production efficiency and reducing energy consumption in crude oil extraction. In this work, a novel NP demulsifier (PPA@KAO) was prepared by chemically modifying the mineral kaolinite (KAO) nanoparticles using γ-Methacryloyl propyltrimethoxysilane (MPS) and polyether-polyquaternium (PPA). The morphology and structure of the PPA@KAO demulsifiers were characterized by FT-IR, SEM, TG, XPS and Zeta potential. The contact angle measurements, interfacial tension (IFT) characterization, and the distribution of nanoparticles in the oil-water phase showed that PPA@KAO have good amphiphilicity and interfacial activity. The demulsification performance of PPA@KAO demulsifiers for a sodium dodecyl benzene sulfonate (SDBS) stabilized crude oil emulsion was studied with bottle method. It was found that the oil-water separation could be completed within 20 min, with a demulsification efficiency of 96.75 % at a dosage of 3 g L−1，pH of 6 and temperature of 30°C. Such a result indicates that the PPA@KAO NP demulsifier can achieve rapid and efficient demulsification for the surfactant-stabilized crude oil emulsion at room temperature. The demulsification mechanism of PPA@KAO for the SDBS-stabilized crude oil emulsion was well revealed, which provides an important synthetic strategy of how obtaining an effective NP demulsifiers by regulating the amphiphilicity and surface functional groups of the nanoparticles.

High-Flux Steady-State Demulsification of Oil-In-Water Emulsions by Superhydrophilic-Oleophobic Copper Foams with Ultra-Small Pores Under Pressure.

3D superwetting materials struggle to maintain high-flux steady-state demulsification for oil-in-water emulsions because the accumulated oil within the material is difficult to discharge rapidly. The water flow shear force can swiftly remove the oil from the anti-fouling surface. In this study, by introducing nanofibers and carbon nanotubes and chemical modification, a superhydrophilic-oleophobic copper foam with pores of several micrometers is prepared, which can achieve a continuous demulsification process with steady-state flux over 57000 Lm-2h-1 for oil-in-water emulsions and rapid hydraulic-driven oil release under an additional pressure of 5kPa. Thanks to the ultra-small pores of the copper foam, the steady-state demulsification efficiency can be still maintained at over 97.5%. During the demulsification process, the accumulation of oil and surfactants within the copper foam can be maintained at low levels, achieving dynamic equilibrium. With the aid of second-stage superhydrophilic copper mesh, the demulsified oil-water mixtures can be rapidly separated. This high-flux, steady-state, and efficient demulsification process shows great potential for industrial applications.

CO2/N2 Triggered Aqueous Recyclable Surfactants for Biphasic Catalytic Reactions in the Pickering Emulsions.

The utilization of Pickering emulsions in interfacial catalysis offers a promising environmental platform for biphasic reactions. However, complicated surface coating or chemical grafting methods are always required to prepare the surface-active catalysts for the Pickering emulsions, since most of them are commercially unavailable. Here, we report CO2-switchable Pickering emulsions for biphasic reactions, in which Pd@Al2O3 nanoparticles are in situ modified by a CO2/N2 responsive surfactant. Compared with the chemical grafted methods, the in situ formed Pickering interfacial catalysts avoid complex chemical modification. Furthermore, efficient demulsification and separation of the oil phase and the products without surfactant contaminations can be achieved by CO2 trigger. The Pickering interfacial catalysis system can also be reformed after the aqueous phase containing the catalyst nanoparticles, and the surfactant is recycled and reused. The strategy is universal for nitrobenzene reductions and alcohol oxidations, providing a convenient and green method for the preparation of Pickering catalysts with commercially available nanoparticles, efficient emulsion separation, and recovery of the catalyst nanoparticles and emulsifiers in various two-phase organic reactions.

Advancing oil-water separation: Design and efficiency of amphiphilic hyperbranched demulsifiers

Hypothesis: An innovative strategy for designing high-performance demulsifiers is proposed. It hypothesizes that integrating mesoscopic molecular simulations with macroscopic physicochemical experiments can enhance the understanding and effectiveness of demulsifiers. Specifically, it is suggested that amphiphilic hyperbranched polyethyleneimine (CHPEI) could act as an efficient demulsifier in oil–water systems, with its performance influenced by its adsorption behaviors at the oil–water interface and its ability to disrupt asphaltene-resin aggregates.Experiments: Several coarse-grained models of oil–water systems, with CHPEI, are constructed using dissipative particle dynamics (DPD) simulation. Following the insights gained from the simulations, a series of CHPEI-based demulsifiers are designed and synthesized. Demulsification experiments are conducted on both simulated and crude oil emulsions, with the process monitored using laser scanning confocal microscopy. Additionally, adsorption kinetics and small angle X-ray scattering are employed to reveal the inherent structural characteristics of CHPEI demulsifiers.Findings: CHPEI demonstrates over 96.7 % demulsification efficiency in high acid-alkali-salt systems and maintains its performance even after multiple reuse cycles. The simulations and macroscopic experiments collectively elucidate that the effectiveness of a demulsifier is largely dependent on its molecular weight and the balance of hydrophilic and hydrophobic groups. These factors are crucial in providing sufficient interfacial active functional groups while avoiding adsorption sites for other surfactants. Collaborative efforts between DPD simulation and macroscopic measurements deepen the understanding of how demulsifiers can improve oil–water separation efficiency in emulsion treatment.

Synthesis of a demulsifier for treating crude oil-in-water emulsion through a straightforward low-temperature process

The separation of oily wastewater is a significant issue in the petroleum industry. In current work, a highly efficient demulsifier (TCDA) was synthesized through a one-step low-temperature method for the purpose of demulsifying O/W emulsions. The structure was characterized using FT-IR and 1H NMR spectra. The oil–water separation ability was evaluated through light transmittance (T%) and oil removal rate (η%) of separated water. The results showed that T% of 88.6 % and η% of 99.8 % could be obtained with the dosage of 30 mg/L at ambient temperature. In addition, TCDA demonstrated good acid and salt resistance. The relative solubility number (RSN), three-phase contact angle, dynamic interfacial tension, zeta potential and optical micrograph were characterized to explore possible demulsification mechanism. It was found that TCDA effectively reduced interfacial tension and penetrated the interfacial membrane, thereby facilitating the separation of O/W emulsion. Overall, these results indicate that the TCDA demulsifier shows promise for using in the demulsification of oily wastewater.

Efficient Demulsification of Crude Oil Emulsion Using Novel Sugar-based Surfactant.

This study aimed to synthesize ecofriendly and low-cost surfactant-based sugar, HA-ST, under mild conditions and a short route via an opening ring of hexadecylsuccinic anhydride (HA) using starch (ST). HA-ST's chemical structure, thermal behavior, and surface activity were evaluated using Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis, and a pendant drop technique. The results indicated HA-ST formation, thermal stability, and surface activity. HA-ST's green character, low cost, and surface activity recommended its use as a demulsifier for crude oil emulsions at different affecting parameters such as temperature, seawater ratio (SR), demulsifier concentration, demulsification time (DT), and pH. HA-ST demulsification efficiency (DE) was evaluated and compared with a commercial demulsifier (CD). The results showed improved HA-ST's DE with rising temperature, SR, demulsifier concentration, DT, and pH. The DE of HAST reached 100% at 50% of SR and 250 ppm of demulsifier concentration; the same results were obtained using CD. In contrast, HA-ST gave relatively lower DE at low SR (10%) with a value of 70% than the obtained using CD with a value of 75%. The green character, low cost, and DE of HA-ST make it suitable for demulsifying crude oil emulsions, especially those containing more than 30% seawater, compared with CD, which commonly contains two or more traditional surfactants.

Demulsification of Water-in-Crude Oil Field Emulsion Using Green Demulsifier Based on Sesamum indicum: Synthesis, Characterization, Performance, and Mechanism

Summary This paper addresses the issues related to poor demulsifier efficiency, low biodegradability, and toxicity of commonly used chemical demulsifiers in the petroleum industry. To overcome these challenges, this study proposes an environmentally friendly demulsifier synthesized from Sesamum indicum (sesame oil). The synthesized demulsifier is characterized using Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). The demulsification test was performed for the synthesized demulsifier through the standard bottle test method using water-in-oil field emulsion. The results indicate that the demulsifier has an excellent dehydration rate and can achieve a demulsification efficiency of 85% within 10 minutes at a concentration of 200 ppm and 100% efficiency in 60 minutes at 70°C and performs better than the commercial demulsifier. The paper summarizes the factors affecting the demulsification process, including settling time, temperature, and demulsifier concentration. Furthermore, the demulsification mechanism is explained through interfacial tension (IFT) measurement, competitive adsorption test between asphaltene and demulsifier, and rheology study of emulsion. Moreover, the disuccinimidyl sulfoxide (DSSO) demulsifier is tested for its biodegradability according to Organization for Economic Co-operation and Development procedure, and the results show that it is completely biodegradable. The outcome of this research provides a promising solution for the demulsification of field emulsions through eco-friendly and efficient demulsifier.

Heterogeneous wettability membrane for efficient demulsification and separation of oil-in-water emulsions

Single super-wetting membranes have been used to treat oily wastewater, but most membranes lack demulsification ability and often exhibit poor separation performance. Herein, we fabricate a desert beetle-like heterogeneous wettability membrane with a superhydrophilic fiber substrate and weakly hydrophilic discontinuous protrusions for demulsification and separation of oil-in-water emulsions. The unbalanced force formed by the difference in hydrophilicity between the substrate and protrusions promotes the demulsification of the emulsion. Additionally, the protrusions capture and gather dispersed oil droplets due to Laplace pressure, forming a layered oil slick. This synergistic effect overcomes the limitation of traditional size-sieving mechanism, enhances the separation performance, and avoids membrane fouling. The heterogeneous wettability membrane demonstrates a 99.8 % gravity-driven oil rejection for various oil-in-water emulsions with a permeability of 2600 L·m−2·h−1. It can also achieve effective separation of high viscosity crude oil emulsions without contamination. Furthermore, molecular dynamic simulations reveal that the heterogeneous wettability structure of the membrane surface promotes the demulsification and separation of emulsified oil droplets. And the presence of two hydration layers is found to be the main reason for the great antifouling property of the membrane. This study provides valuable insights for the design of separation membranes for oil-in-water emulsions and the advancement of separation technology.

Pretreatment of alkali/surfactant/polymer (ASP)-flooding produced wastewater by electron beam radiation to improve oil-water separation

The management of wastewater produced from alkali/surfactant/polymer (ASP) flooding, known for its considerable volume and high emulsion stability, poses a challenge in oilfields globally. This study has demonstrated that ionizing irradiation is a promising pretreatment method for ASP wastewater to improve oil-water separation. After a settling time of 1 h, approximately 69.5% of oil remained in the raw ASP wastewater, while only 20–29% of the oil persisted in the liquid phase following radiation at absorbed doses ranging from 0.1 to 5.0 kGy. A noticeable increase in the size of oil droplets and reduction in turbidity was observed after irradiation. Further analysis revealed that the combination of surfactant, sodium dodecyl sulfate (SDS) and alkali exhibits a synergistic impact, leading to a substantial reduction in interface tension of ASP wastewater. Notably, ionizing irradiation induces several key changes that are crucial for efficient demulsification. The transformation of the wastewater's rheological behavior from pseudoplastics to a Newtonian fluid accompanied by a reduction in viscosity, the increased interfacial tension at both liquid-air and liquid-oil interfaces, along with the degradation of organic components such as partly hydrolyzed polyacrylamide (HPAM) and SDS, all contribute to the coalescence and floatation of oil droplets.

An intelligent dual stimuli-responsive Pickering emulsion for highly efficiently producing waste frying oil-based biodiesel

Directionally converting waste frying oil (WFO) to biodiesel is not only a crucial strategy for its clean and efficient utilization, but also a promising alternative for the large-scale substitution of petroleum-based fuels. However, the challenge of reducing mass transfer resistance between the alcohol/oil bi-liquid phases remains a major obstacle in the industrialization of WFO-based biodiesel (WFOBB). Additionally, both rapid emulsification and efficient demulsification still present bottlenecks that need to be addressed in emulsion reaction. Herein, the present study successfully demonstrates the fabrication of a novel Pickering interfacial catalyst with immobilized Brønsted-Lewis di-acid functionalized ionic liquids and photosensitizer (P(5[DVB]-[SP]-[ILs-2FeCl3])@SiO2@Fe3O4) through layer-by-layer self-assembly. This novel Pickering interfacial catalyst efficiently constructed an intelligent magneto-optical dual stimuli-responsive Pickering emulsion. The intelligent Pickering emulsion enables precise control over amphiphilic interfacial catalyst using Vis-light regulation, thereby significantly enhancing mass transfer in the biphasic methanol-WFO system while providing an optimal hydrophobic micro-environment for highly efficient WFOBB production. The intelligent Pickering catalyst exhibits exceptional catalytic performance in achieving a 92.4% yield of WFOBB, which is currently the highest reported value under similar conditions. Furthermore, the efficient demulsification and separation of this Pickering interfacial catalyst could be achieved through the synergistic effect of UV-irradiation-induced hydrophilicity and its magnetic property. These findings present a new avenue for advancing the development of WFOBB technologies, while also offering promising prospects for industrial applications of Pickering emulsion systems.

Fabrication of a poly(N-isopropylacrylamide)-grafted alginate composite aerogel for efficient treatment of emulsified oily wastewater

The treatment of emulsion wastewater poses significant challenges. In this study, a novel porous material, namely esterified bagasse/poly(N, N-dimethylacrylamide)/sodium alginate (SBS/PDMAA/Alg) aerogel, was developed for efficient demulsification and oil recovery. By grafting a poly(N-isopropylacrylamide) (PNIPAM) brush onto the SBS/PDMAA/Alg skeleton through free radical polymerization, the resulting aerogel exhibits both surface charge and a molecular brush structure. The aerogel demonstrates remarkable demulsification efficiency for cationic surfactant-stabilized emulsions at various concentrations, achieving a demulsification efficiency of 95.6% even at an oil content of 100 g L−1. Furthermore, the molecular brush structure extends the application range of the aerogel, enabling a demulsification efficiency of 98.3% for anionic and non-ionic surfactant-stabilized emulsions. The interpenetrating polymer network (IPN) structure formed by SBS, PDMAA, and alginate enhances the mechanical stability of the aerogel, enabling a demulsification efficiency of 91.3% even after 20 repeated cycles. The demulsification ability of the composite aerogel is attributed to its surface charge, high interfacial activity, and unique brush-like structure. A demulsification mechanism based on the synergistic effect of surface charge and molecular brush is proposed to elucidate the efficient demulsification process.

Nanomagnetic Cyclodextrin decorated with ionic liquid as green and reversible Demulsifier for breaking of crude oil emulsions

Application of the chemical demulsifiers is the best choice for breaking the water in crude oil (W/O) emulsions in the petroleum industry. Here, novel, environmentally friendly, efficient, and easily reusable Fe3O4 nanomagnetic compounds based on imidazolium-decorated cyclodextrin were successfully synthesized and applied to demulsify the water in crude oil (W/O) emulsions. At first, Fe3O4 nanoparticles were decorated with β-cyclodextrin (β-CD) to prepare Fe3O4@β-CD@IL magnetic nanoparticles. Then, imidazole (Im) was separately reacted with 1-bromohexane and 1-bromodecane to prepare [Im-C6][Br] and [Im-C10][Br] ionic liquids, respectively. The prepared imidazolium-based ionic liquids were reacted with N-propyltriethoxysilane to synthesize [ImSi-C6][Br] and [ImSi-C10][Br]. Finally, [ImSi-Cn][Br] was immobilized on Fe3O4@β-CD to obtain nanomagnetic demulsifiers. Structure of the synthesized compounds was confirmed using different methods such as FT-IR, NMR, and elemental analysis. TGA, VSM, and FESEM methods were used to investigate the thermal stability, magnetic properties, and the morphology, respectively. Fe3O4@βCD and Fe3O4@βCD@[ImSi-C10][Br] nanoparticles respectively showed the particle size in the range of 40–70 nm and 50–80 nm. After grafting the imidazolium-based ionic liquid on the surface of support, the magnetization number reduced from 25.6 emu/g for Fe3O4@β-CD to 24.9 emu/g for Fe3O4@β-CD@[ImSi-C10][Br]. Synthesized material employed to break the (10:90 and 30:70 Vol%) W/O emulsions at the concentration range of 1000–5000 ppm. The maximum demulsification efficiency (DE%) of 92 % was obtained using a Fe3O4@β-CD@[ImSi-C10][Br] at 5000 ppm for (30:70 Vol%) W/O emulsion within 24 h. Interfacial tension (IFT) values decreased with increasing the DE%. The Fe3O4@βCD@[ImSi-C10][Br] demulsifier was reused five times with acceptable yields. The cooperation of imidazolium and β-CD in the green nanomagnetic demulsifiers led to the efficient demulsification of the W/O emulsions. The preparation of different ionic liquids or changing the counter anions are our potential future directions for this research. Demulsification at high demulsifier concentration can be considered a limitation of the nanomagnetic cyclodextrin decorated with ionic liquid. But due to the low amount of ionic liquid immobilized in the synthesized demulsifier, the cost of the final demulsifier is lower that other demulsifiers with full ionic liquid backbones, which increases its potential for industrial applications.

Reversible emulsification based on pH-responsive surfactant with dynamic imine bond

Efficient demulsification of emulsions is crucial in heavy oil transportation, interfacial reactions, and emulsion polymerization applications. Surfactants that are responsive to the environment have the ability to alter their surface activity in a dynamic manner. However, these types of surfactants typically require a significant amount of energy and may be less efficient. The present study involved the preparation of a surfactant with dynamic covalent bonding and pH-responsive property. This was achieved through the creation of dynamic imine bonds between decyloxybenzaldehyde (DOBA) and sodium 3-amino-1-propanesulfonate (AP) via a Schiff base reaction to synthesize dynamic covalent surfactant CB. The present study aimed to investigate the impact of various pH environments on the conversion rate and interfacial tension of surfactant CB. To achieve this objective, 1H NMR, FTIR, and IFT tests were conducted. The results confirmed the reversible conversion of the dynamic imine bond with pH. Furthermore, the dynamic imine bonded surfactant demonstrated the ability to complete at least three emulsification-breakage cycles. The present investigation introduces a novel approach for the synthesis of pH-responsive surfactants through the utilization of dynamic covalent bonds.

Demulsification efficiency and mechanism of hydrophobic carbon chains modified hyperbranched polyethylenimide on oil-in-water emulsion

A series of amphiphilic hyperbranched polyethylenimine (HPEI-Cn) with different length hydrophobic carbon chains were synthesized by amidation modification of hyperbranched polyethylenimine (HPEI), which can be used for separation of oil-in-water emulsion. The demulsification effect of HPEI-Cn under different demulsifier concentration, temperature, settling time and pH value were evaluated by bottle test method. The results indicated that the demulsification efficiency (DE) of HPEI-Cn increased with the increase of graft length of carbon chain. Encouragingly, the HPEI-C16 had the characteristics of small amount (50 mg/L), short settling time (30 min) and wide temperature adaptation range (20–60 °C). Through three-phase contact angle tests (CA), dynamic interfacial tension tests (IFT), elastic modulus analysis, Zeta potential and microscope observation, the demulsification mechanism of HPEI-Cn was systematically revealed. The excellent DE of HPEI-C16 was attributed to the high interfacial activity and appropriate length of hydrophobic groups. On the one hand, the high interfacial activity drives hyperbranched macromolecules to rapidly diffuse and adsorb to the oil-water interface. On the other hand, it contains appropriate hydrophobic carbon chains C16 to flocculate and coalesce oil droplets, thus achieving efficient demulsification.

Efficient Demulsification Performance of Emulsified Condensate Oil by Hyperbranched Low-Temperature Demulsifiers.

Focusing on the problem of poor demulsification performance of light crude oil emulsions in low-permeability oilfields at low temperatures, the composition of the emulsion samples, clay particle size distribution, and the viscosity-temperature relationship curve of samples were analyzed. Based on the results of emulsion composition analysis and characteristics, the bottle test method was used to analyze the demulsifying effect of different commercial types of demulsifiers, revealing the demulsification mechanism. The field tests confirm the demulsification capabilities of Polyoxyethylene polyoxypropylene quaternized polyoxyolefins surfactants (PR demulsifiers). The results reveal that PR demulsifiers combine the features of decreasing the interfacial tension between oil and water and adsorbing SiO2, allowing for quick demulsification and flocculation at low temperatures. This research serves as a theoretical and practical foundation for the study and advancement of low-temperature demulsification technology in oilfields.

Optimizing chaotic frequency electric fields for deformation analysis of droplets based on numerical modeling

Chaotic pulse group (CPG) electric field has already been proposed to achieve demulsification of water-in-oil (W/O) emulsions; however, the electric field parameters of the CPG electric field for efficient demulsification of emulsions are unknown. Therefore, in this study, the numerical model of droplet deformation under the action of electric field was established by coupling the flow field and electric field, and the effectiveness of the model was verified by comparing with the experimental results. In the numerical model, the electric field parameters are optimized by droplet deformation; moreover, the influence of surface tension and oil viscosity on the optimal electric field parameters is discussed; the deformation of droplets under the optimized CPG electric field was analyzed. The results show that when the droplet radius is 1 mm, the optimal electric field strength is 612 kV/m, the optimal pulse width is 0.023 s, and the optimal pulse rest width is 0.017 s. The increase in interfacial tension leads to the increase in optimal electric field strength, and the decrease in optimal pulse width and pulse rest width. The increase in oil viscosity leads to an increase in the optimal electric field parameters. With the increase in interfacial tension and oil viscosity, their influence on the deformation of droplets gradually decreases. Droplets of different sizes could find their own optimal electric field parameters in the CPG electric field, so as to achieve the maximum deformation. The results provide valuable guidance for the selection of electric field parameters in CPG electric field industrial applications.