智能破乳剂

... 智能破乳材料，探索新型材料在乳状液调控中的应用潜力，以此实现乳状液之间的 ... 蒸汽吞吐开采中的原油乳化特征及有效破乳体系研究[J]. 中国农业科技导报, 2023 ...

开关型表面活性剂是指能够通过人为的触发手段，实现表面活性剂分子结构的可逆转化，进而实现其宏观物理化学性质的可控可逆变化的新型高端表面活性剂。本文介绍了开关型 ...

利用碳气凝胶疏水亲油的表面性能，与水包油乳液接触时，油滴被吸附储存而水被排斥在外面从而达到破乳分离效果。另外，乳液的稳定性也会影响碳气凝胶的分离效果，水包油乳液体系 ...

本文针对南海北部湾A油田储层特征，构建一个机理协同的技术系统，创新性地将水力脉冲波场的物理解堵、传质强化功能，与精心设计的智能化学酸液体系的深部溶蚀、自转向及长效 ...

破乳剂的发展过程经历了由低分子到高分子,再到超高分子表面活性剂,由硫酸盐,磺酸盐类的阴离子表面活性剂到有机合成高分子非离子表面活性剂,按照引发剂的不同以及PO/EO配比 ...

本研究设计合成了一种具有温敏型开关特性、表面活性的共聚物(THFAA-NIPAM-PEGMA)，是一种可以仅通过改变温度就可以控制其乳化/破乳性质的新型表面活性剂。

微波加热降低了催化剂的起活温度，提升了催化剂的低温活性，通过比较发现 ... 破乳手段。它可以产生高频变化的电磁场，破坏油水界面膜的ζ电位，微波对原油的内 ...

微波热解技术是一种处理含油污泥的高效方法,微波的热效应和非热效应可以促进油水乳状液的破乳,由于微波加热的选择性加热,穿透性,即时性等特点,微波技术被用于加热含油污泥 ...

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Functional dyes exhibit intriguing properties in response to external stimuli related to their optical, electronic, structural, and energetic characteristics and enable unique stimuli-responsive functions in materials by collaborating with polymers, particularly when chemically incorporated into the polymer structures. As well as the structures and properties of functional dyes, polymers, assemblies, and materials, the interactions between these components are important to the functions of materials. In this review, we introduce our recent studies conducted in the past half decade on stimuli-responsive smart polymers and polymeric materials based on functional dyes that are chemically incorporated into the polymer structures, with a special focus on light, force, electric fields, and chemicals including water in a variety of external stimuli. For example, these polymers and materials offer switchable adhesion, mechanical actuation, and chemical sensing. Functional dyes offer fascinating properties in response to external stimuli and enable unique stimuli-responsive functions in materials by chemical incorporation into polymers. In this review, we highlight our recent studies conducted in the last half decade on stimuli-responsive smart polymers and polymeric materials offering, for example, switchable adhesion, mechanical actuation, and chemical sensing based on functional dyes that are chemically incorporated into the structures, with a particular focus on the stimuli of light, force, electric fields, and chemicals including water.

Liquid-liquid interfaces offer highly controlled, flexible, and adaptable platforms for precise molecular assemblies, enabling the construction of sophisticated functional materials. Interfacial assemblies of specific nanoparticles (NPs) and ligands can alter their physicochemical states under external stimuli, leading to macroscopic dynamic transformations at the interface. This Review summarizes and analyzes the recent advances of the assembly and disassembly behaviors of various stimuli-responsive nanoparticle surfactants (NPSs) at liquid-liquid interfaces, focusing on their responsive behaviors when exposed to external stimuli and the interaction forces between interfacial molecules. Additionally, we outline recent advancements in applications such as reconfigurable all-liquid devices, all-liquid 3D printing, and chemical reaction platforms. Finally, we discuss current challenges and future prospects for the development of applications in this rapidly evolving field.

Intelligent polymers responsive to the environment have aroused widespread interest in many applications of materials and interfaces. However, sensitive control of the oil-water interface remains a major challenge, using reversible self-assembly of macromolecules induced by external stimuli. Here, we synthesized a new amphiphilic triblock copolymer responsive to pH and UV light via reversible addition–fragmentation chain transfer (RAFT) aqueous polymerization. Poly(methacrylic acid) (PMAA) acts as the hydrophilic block; poly(N, N-dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(methacrylamide azobenzene) (PMAAAB) are the hydrophobic blocks with responsiveness. The as-synthesized polymer was measured regarding UV–vis transmittance and contact angle to verify the tunable amphiphilicity and wettability by the double stimulation. The newly developed dual-responsive polymer was applied for oil/water separation and controlled dye release, where methylene red (MR) was chosen as the representative adsorbate. With the synergic stimulation of pH and UV light, efficient separation for oil-in-water emulsions (separation efficiency: 66.8% in 15 min) and excellent desorption for adsorbed dyes (desorption efficiency: 93.8% in 15 min) are achieved.

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At present, there are many works on the influences of partially hydrolyzed polyacrylamide (HPAM) and surfactant on the stability and treatment of O/W emulsion produced by surfactant–polymer (SP) flooding. However, there are few related reports on the effects of HPAM and surfactant on the demulsification of W/O crude oil emulsion produced by SP flooding. Especially, there is no report on the effect of the surfactant type. In this paper, sodium dodecyl sulfate (SDS), octylphenol polyoxyethylene ether (OP-10), and alkyl C16–18 hydroxypropyl sulfobetaine (HSB1618) were selected as representatives of the anionic surfactant, nonionic surfactant, and zwitterionic surfactant, respectively. Demulsification experiments and interface behavior experiments were conducted to investigate their influences on the demulsification performance of a demulsifier D1. The results showed that the order of the negative effect of the surfactant type on dehydration speed and the dehydration rate of D1 was HPAM + OP-10 > HPAM + HSB1618 > HPAM + SDS. There is no difference in the effect of three surfactants on the conformation adjustment of D1 at the W/O interface, but the properties of the composite W/O interface formed by them and D1 were different. The coalescence time was longest when there were HPAM and OP-10 in water, while the lg(G1′/Gdemulsifier′)/lgG1′ was the smallest, which led to the most difficult demulsification of W/O emulsion. This work can guide surfactant selection during SP flooding from the perspective of produced fluid treatment.

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In the alkaline-surfactant-polymer flooding emulsion, oil droplets with various sizes exhibited different interfacial properties, resulting in different stabilization and destabilization behaviors. In view of this, it is expected to achieve outstanding oil-water separation efficiency by screening targeted demulsifier for oil droplets with different size ranges (0∼1, 1∼5 and 5∼10 μm). Based on the size effect of oil droplets, a series of multibranched polyether-polyquaternium demulsifiers that integrated different charge neutralization and interfacial displacement functionalities were designed by regulating the cationicity and EO:PO ratios. As a result, the most effective polyether-polyquaternium variant for each size range of oil droplet was screened out. By employing these three selected polyether-polyquaternium variants in a sequential batch demulsification test, the maximum demulsification efficiency of 95.1% was obtained, which was much higher than that using a single polyether-polyquaternium variant (82.5%, 80.5% and 83.8%). The adsorption behaviors of polyether-polyquaternium variants on the oil/water interface were investigated by the molecular dynamics simulation. Moreover, the interfacial properties and oil droplet size variations during the demulsification process were monitored, so as explore the demulsification mechanism. This demulsification protocol based on the size effect of oil droplets with its excellent oil-water separation performance offered significant technical promise for the emulsified oil wastewater disposal.

The increasing exploitation of fossil resources needs to shift people's attention to developing unconventional reservoir resources. Polyacrylamide-based emulsion drag reducers can effectively reduce the turbulence of fracturing fluid and improve oil recovery, but their release effect is poor, which limits their practical application. Here, we constructed a pH-responsive inverse polymer emulsion of poly(acrylamide-2-acrylamido-2-methylpropanesulfonic acid). Interestingly, HOA/Tween 80 exhibits remarkable pH-responsive behavior, which enables the monomer emulsion to change the type of emulsion under pH stimulation. Our results propose that the P(AM-AMPS) polymer emulsion is eluted with the same aqueous phase as the W/O P(AM-AMPS) polymer emulsion, thereby achieving the effect of drag reduction. P(AM-AMPS) can be rapidly released from the inverse polymer emulsion within 70 s upon pH stimulation, the drag reduction rate of which was 60.4%. Obviously, the inverse polymer emulsion prepared by a pH-responsive surfactant not only has good stability but also can achieve rapid release of the polymer upon pH stimulation, which supplies an interesting indication to explain why a balance exists between the stability of the emulsion and release of P(AM-AMPS).

Numerous cationic magnetic nanoparticles (MNPs) have previously been developed for demulsifying oil-in-water (O/W) emulsion, and results showed that the cationic MNPs could effectively flocculate and remove the negatively charged oil droplets via charge attraction; however, to the best of our knowledge, there are no research reports regarding the synergetic influence of both the positive charge density and interfacial activity of MNPs on the demulsification performance. In this study, three tertiary amine polymer-grafted MNPs, namely, poly(2-dimethylaminoethyl acrylate)-grafted MNPs (M-PDMAEA), poly(2-dimethylamino)ethyl methacrylate)-grafted MNPs (M-PDMAEMA), and poly(2-diethylaminoethyl methacrylate)-grafted MNPs (M-PDEAEMA), were synthesized and evaluated for their demulsification performance. Results demonstrated that a high positive charge density and superior interfacial activity of MNPs could cause partial oil droplet re-dispersion when excessive MNPs were introduced, leading to a lower magnetic separation efficiency and narrower demulsification window. Herein, a demulsification window is defined as a range of nanoparticle dosages in which the MNPs can effectively demulsify the O/W emulsion under certain conditions. For highly positively charged MNPs, their good interfacial activity could aggravate the formation of a narrower demulsification window. When tertiary amine polymer-grafted MNPs carried a lower positive charge density or weak interfacial activity, that is, M-PDMAEA at pH 4.0, M-PDMAEMA at pH 5.0-9.0, and M-PDEAEMA at pH 9.0-10.0, wide demulsification windows were observed. Additionally, a recycling experiment suggested that MNPs could maintain high demulsification efficiency up to at least five cycles, indicating their satisfactory recyclability. The three tertiary amine polymer-grafted MNPs can be potentially used for efficient demulsification from surfactant-free O/W emulsion in various pH ranges.

In this study, a combined approach of molecular dynamics (MD) simulations and experimental bottle tests was employed to systematically investigate the demulsification performance and underlying mechanisms of two distinct demulsifiers—Demulsifier X (SP/BP series and alcohol-initiated polyethers) and Demulsifier Y (AP/AE series and amine-initiated polyethers)—targeting polymer-containing oil-in-water (O/W) emulsions derived from heavy oil polymer flooding. Molecular models for heavy oil, saline water, partially hydrolyzed polyacrylamide (HPAM), and demulsifiers were constructed using BIOVIA Materials Studio software. Their dynamic behaviors at the oil–water interface were simulated within three distinct saline systems containing NaCl, CaCl2, and MgCl2, respectively. Simulation results indicated that the demulsifiers effectively displaced interfacial HPAM molecules, increased interfacial tension, and reduced interfacial interaction energy. Experimental bottle tests, evaluating the effects of settling time, temperature, and concentration on dehydration rates and oil content, confirmed that Demulsifier Y outperformed Demulsifier X. Specifically, Demulsifier Y achieved superior dehydration rates with lower dosages, shorter settling times, and reduced temperature requirements under optimal conditions. This work provides both microscopic mechanistic insights and macroscopic experimental validation for the screening and application of high-efficiency demulsifiers.

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Addressing the issue of inadequate temperature tolerance in traditional polymers, in this study, we successfully executed a one-step synthesis of intelligent–responsive polymers which have excellent adaptability in water–gas alternating displacement scenarios. Utilizing the fatty acid method, we produced OANND from oleic acid (OA) and N,N-dimethyl-1,3-propanediamine (NND). Upon testing the average particle size in the aqueous solution both prior and subsequent to CO2 passage, it became evident that OANND assumes the form of a small-molecule particle in the aqueous phase, minimizing damage during formation. Notably, upon CO2 exposure, it promptly organizes into stable micelles with an average size of 88 nm and a relatively uniform particle distribution. This unique characteristic endows it with a rapid CO2 response mechanism and the ability to form a highly resilient gel. In the exploration of viscoelastic fluids, we observed the remarkable behavior of the AONND aqueous solution when CO2/N2 was introduced. This system displayed repeatable transitions between aqueous and gel states, with the highest viscosity peaking at approximately 3895 mPa·s, highlighting its viscosity reversibility and reusability properties. The rheological property results that we obtained indicate that an elongated micellar structure is present in the solution system, with the optimal concentration ratio for its formation determined as 0.8, which is the molar ratio of the OANND-NaOA system. In the sealing performance tests, a 1.0 wt% concentration of the gel system exhibited excellent injectability properties. At 80 °C, this gel effectively reduced the permeability of a sand-filled model to 94.5% of its initial value, effectively sealing potential leakage paths or gas fluxes. This remarkable ability to block leakage paths and reduce seepage capacity highlights the material’s superior blocking effect and erosion resistance properties. Furthermore, even at a temperature of 90 °C and an injection pore volume (PV) of 3, this plugging system could reduce the permeability of a high-permeability sand-filled model to over 90% of its initial value.

The issue of pipeline scaling and oil-water separation caused by treating produced water in Alkali/Surfactant/Polymer (ASP) flooding greatly limits the wide use of ASP flooding technology. Therefore, this study of the demulsification-flocculation mechanism of oil-water emulsion in ASP flooding produced water is of great importance for ASP produced water treatment and its application. In this paper, the demulsification-flocculation mechanism of produced water is studied by simulating the changes in oil-water interfacial tension, Zeta potential and the size of oil droplets of produced water with an added demulsifier or flocculent by laboratory experiments. The results show that the demulsifier molecules can be adsorbed onto the oil droplets and replace the surfactant absorbed on the surface of oil droplets, reducing interfacial tension and weakening interfacial film strength, resulting in decreased stability of the oil droplets. The demulsifier can also neutralize the negative charge on the surface of oil droplets and reduce the electrostatic repulsion between them which will be beneficial for the accumulation of oil droplets. The flocculent after demulsification of oil droplets by charge neutralization, adsorption bridging, and sweeping all functions together. Thus, the oil droplets form aggregates and the synthetic action by the demulsifier and the flocculent causes the oil drop film to break up and oil droplet coalescence occurs to separate oil water.

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Currently, block polyether demulsifiers synthesized through the ring‐opening polymerization of ethylene oxide and propylene oxide are predominantly utilized in oilfields. However, their synthesis requires high‐temperature and high‐pressure conditions, accompanied by significant safety risks and economic costs. Consequently, this study successfully prepared a series of novel block polyacrylate demulsifiers (P(MA‐b‐DBC)) via reversible addition–fragmentation chain transfer (RAFT) polymerization using methyl acrylate (MA) and acryloyloxyethyl benzyl dimethyl ammonium chloride (DBC) as monomers. Through systematic single‐factor optimization with demulsification efficiency under coupled electric field as evaluation criteria, the optimal synthesis conditions were established as follows: dipropylene glycol methyl ether/water mixed solvent (mass ratio of 1:1.5), monomer concentration of 40 wt% (MA:DBC mass ratio of 1:1.5), chain transfer agent CTA‐3 containing three trithiocarbonate groups (0.4 wt% relative to monomers), initiator dosage of 0.5 wt% relative to monomers, and sequential polymerization at 70°C (5 h per monomer stage with MA polymerized first). Under optimized operational parameters (demulsification temperature 80°C, optimal P(MA‐b‐DBC)‐3 dosage 200 mg/L, applied voltage 2500 V, and 60 min treatment), the dehydration rate reached 98% for crude oil emulsion containing 20% water content. Notably, this demulsification performance proved comparable to the conventional block polyether demulsifier. The findings provide valuable insights for developing new crude oil demulsifiers.

Emulsified oil wastewater, characterized by diverse sources, low biodegradability, and high ecotoxicity, imposes a severe hazard on aquatic organisms and human health when released untreated. Flocculation stands out among current emulsified oil treatment methods for its simplicity, affordability, and role as a fundamental unit operation in water treatment processes. However, existing flocculants suffer from insufficient demulsification efficiency, ambiguous structure-property relationships, and unclear mechanisms.​ In this study, a series of cationic and hydrophobic β-cyclodextrin (β-CD)-based flocculants (β-CD-AAL) with varying charge density (CD), contact angle (CA), and graft chain length (CL) were synthesized via thermally initiated radical graft copolymerization by introducing quaternary ammonium groups, hydrophobic alkyl chains, and acrylamide onto the natural polymer β-CD. Systematic experiments were conducted to correlate the oil removal performance of β-CD-AAL flocculants with their CD, CA, and CL, revealing structure-property relationships underlying emulsified oil removal. Experimental data were fitted using a quadratic polynomial model, while density functional theory (DFT) calculations quantified the binding energies between the flocculant's characteristic structures and the contaminant, thereby revealing their relative influence on emulsified oil flocculation from both mathematical and molecular-level perspectives. The results indicated that CD exerted the greatest influence on flocculation performance, followed by CA, while CL had the least effect. Floc growth analysis demonstrated that CD governs initial demulsification through charge neutralization, while CA and CL control subsequent flocculation via hydrophobic association and adsorption bridging after charge neutralization saturation. This work furnishes technical guidance and a mechanistic underpinning for the rational design of high-efficiency flocculants and effective control of emulsified oil wastewater.

Sulfur polymers, prepared by inverse vulcanization using elemental sulfur and vinylic monomers, are emerging functional materials of current research interest; however, sulfur polymers suffer from limited water solubility due to the hydrophobic nature of conventional comonomers and sulfur. Herein, the preparation of ionic liquid (IL)‐containing sulfur polymers are reported using the hydrophilic ionic liquid, 1‐allyl‐3‐vinylimidazolium chloride (AVImCl) as a comonomer. The introduction of IL significantly enhances the hydrophilicity of sulfur polymers, enabling them to dissolve in water. Benefiting from the thorough contact with aqueous mercury ions, the resultant sulfur polymer possesses high uptake capacity (436 mg g−1). After binding mercury, a coordination complex is formed and precipitated. The charged sulfur polymers gain a new application in demulsification. The polymer quickly breaks oil‐in‐water (O/W) emulsions through anion exchange between Cl− of the polymer and dodecylbenzenesulfonate (DBS−) of the surfactant. In addition, the polymer has a growth inhibitory effect against Staphylococcus aureus. The integration of IL and elemental sulfur provides a novel approach to modifying the wettability of sulfur polymers. Also, this novel water‐soluble IL‐containing sulfur polymer, with mercury capture, demulsification, and antibacterial activity, can be considered as a multifunctional material in practical water purification.

The polymers of N,N‐diethylacrylamide (DEA) exhibit temperature‐dependent sensitivity attributable to the presence of both hydrophilic and hydrophobic groups. However, their lower critical solution temperature (LCST) is only 25 °C, a limitation that restricts their practical applications. Previous studies have shown that the incorporation of cationic monomers for copolymerization can enhance the LCST of polymers. In this study, dimethyldiallylammonium chloride (DMDAAC) and DEA were selected for copolymerization to obtain a series of thermosensitive water‐soluble polymers, poly(DMDAAC‐co‐DEA). Structure and properties were characterized using FT‐IR, 1H NMR, TG‐DSC, and surface tension test. Combined with the critical phase transition mechanism, it was determined that the hydrophilicity of the polymer underwent a gradual increase in proportion with the increase of DMDAAC blocks in polymers, and the LCST exhibited an increase of up to 36.8 °C. The relationship between polymer structure and demulsification performance was also explored, as represented by the application of O/W emulsion. The experimental findings demonstrated that all poly(DMDAAC‐co‐DEA) products exhibited effective demulsification performance. The demulsification rate of the polymers with 30%, 50%, and 70% of DMDAAC could reach 97.03%, 98.20%, and 98.40% respectively, which shows great potential for the petroleum demulsification application.

Hydrogel materials with hydrophilic cross-linked network exhibit remarkable super-wettability, enabling their widespread application in oily wastewater treatment. However, the single and loose structure lacks sufficient strength and porosity to resist long-term degradation. Herein, a structural synergistic molecular strategy was reported to introduce reinforcing phase structures and interfacial active sites into the polymer networks for long-term oil-water emulsion separation. The carbon skeleton was uniformly interspersed through the strongly hydrogen-bonded polymer chains via covalent bonds, resulting in a hydrogel network with high mechanical strength and exceptional flow conductivity, which maintained a separation flux of 1233 L m-2 h-1 after 20 separation cycles under gravitational force. Dense negative charges on the surface disrupted the internal charge stability of the oil-water emulsion, leading to remarkable demulsification with a separation efficiency exceeding 99 %. Simultaneously, the strong redox reaction of the photoheterojunction effectively removed organic dyes under visible light, enhancing the overall antifouling performance. This study provided a feasible strategy at the molecular level for optimizing the suitability of hydrogels for oil-water emulsion separation.

The effect of the water-soluble polymer (partially hydrolyzed polyacrylamide, HPAM) in produced water on the demulsification process of the electric field was studied by molecular dynamics simulations. By comparing the coalescence process of oil droplets in the electric field environment with or without HPAM, we find that HPAM in the water phase can promote the coalescence of nearly oil droplets but hinder the deformation and migration of oil droplets. By analyzing the radial distribution function and interaction energy between molecules, we conclude that the existence of HPAM molecules can reduce the hydrophilicity of other molecules through their strong interaction with water, and sodium ions (Na+) have strong interaction with bound water in the process of breaking away from HPAM, thus leading the movement of water molecules. At the same time, the influence of HPAM molecules located between the two oil droplets on the demulsification process was also studied. The HPAM molecules and sodium ions located between the two oil droplets also affected the coalescence process of oil droplets under an electric field by interacting with water.

The rapid development of industries has intensified the issue of oily wastewater pollution, necessitating sustainable solutions. Biomass aerogels, known for their environmental friendliness and biocompatibility, offer promising prospects for oil-water separation. This study fabricated a polyamidoamine (PAMAM)-modified chitosan/cellulose interpenetrating polymer network aerogel via sequential cross-linking and directional freeze-drying. This method endowed the aerogel with excellent mechanical properties, including good strength at a low density (0.06-0.11 g/cm3), high anisotropy at 80 % strain, a high specific surface area (1.93-12.56 m2/g), and hydrophobicity (WCA = 139.5°). The aerogel exhibited outstanding separation efficiencies for the carbon tetrachloride/water mixture (5501.85 L·m-2·h-1) and water-in-oil emulsions (4198.60 L·m-2·h-1, 96.67 %), as well as a removal rate of 61.24 % for the cationic dye RhB. A "demulsification-adsorption synergistic separation" mechanism involving dendritic PAMAM polymers and hydrophobic functional groups was proposed, with performance initially increasing and then decreasing as the PAMAM generation number increased. Despite certain limitations, such as sensitivity to environmental factors, the prepared all-biomass aerogel offered a green, efficient, and mechanically robust solution for the treatment of oily wastewater. This study provided a sustainable strategy for fabricating multifunctional hydrophobic aerogels, paving the way for advanced applications in environmental remediation.

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In this study, a polymeric magnetic emulsion-breaking compound of ferric tetroxide and cationic polyacrylamide (Fe3O4@CPAM) was designed and synthesized, and its functional groups, chemical bonding, magnetic properties, and thermal stability were characterized. Finally, the pH-responsive behavior of the microwave-modified magnetic nanoparticles (MNPs) in terms of their demulsification effect on thick oil-in-water emulsions was investigated using the morphology and distribution of oil droplets, zeta potential, and contact angle of the MNPs. The results showed that with increasing pH, the water separation of the emulsion initially decreased and then increased, and the best emulsion-breaking effect was achieved at pH 3. The highest water partition of the emulsion was 64.39% at a concentration of 175 mg/L for Fe3O4 MNPs alone before modification. Under the same conditions, the water separation rate of the emulsion for Fe3O4@CPAM was 78.95%, indicating that, compared with the conventional demulsification method, microwaves can promote oil-water separation. The highest water separation rate of MNPs before microwave modification was 85% at pH 3, whereas the water separation rate of MNPs after microwave modification reached 94.70% under the same conditions. This proves that microwaves and modified MNPs have a synergistic emulsion-breaking effect, mainly because the combination of microwaves and polymer modification enhances the hydrophobicity and neutralizes the charge of the MNPs, thus improving the emulsion-breaking efficiency.

To ensure safety and efficiency in the production and transportation of fuel oil, there is an urgent demand to develop intelligent emulsifiers to deal with this challenge. Fe3O4@PDA-P(NIPAM-b-MAA-b-LMA) (MNPDNML) microspheres were prepared by modifying polydopamine and the triblock polymer brush P(NIPAM-b-MAA-b-LMA) on the surface of Fe3O4 nanoparticles via oxidative autopolymerization and SI-RAFT polymerization. Therefore, the MNPDNML microspheres exhibited sensitive stimulus-responsive behavior to pH, temperature, near-infrared (NIR) laser radiation, and magnetic fields. The stability state of the emulsion could be modulated by changing pH, temperature, magnetic field, and NIR radiation, and the reversible switching of emulsification/breaking behavior could be reached at least 10 times. This "intelligent emulsifier" exhibited high emulsification efficiency, long-term stability, and on-demand emulsification/breaking properties. It was notable that MNPDNML microspheres showed excellent emulsification ability for olive oil, kerosene, gasoline, and crude oil, which allowed the material to be widely used in the controlled transportation and separation of fuel oil.

Recently, stimuli-responsive emulsions have been widely applied due to their excellent structural stability, biocompatibility, and environmental friendliness. For this application, the emulsion needs to be able to respond quickly to environmental stimuli with controlled stabilization and destabilization. This paper reports a novel composite Pickering emulsifier using Fe3O4 as the core, silica as the intermediate layer, and chitosan as the outer shell, which possesses a pH/magnetic dual responsive feature when deionized water is used as the water phase, and liquid paraffin is used as the oil phase to form an emulsion. Fe3O4@SiO2@chitosan has good paramagnetism and pH responsiveness to realize controlled magnetic and pH-responsive breaking of an emulsion when needed. The size of the composite emulsifiers ranged from 90 nm to 120 nm. The strong magnetic responsiveness enables rapid emulsion breaking at pH=3-11. When used as stabilizer particles, the chitosan shell behaves differently depending on pH. At pH≤2, fully protonated chitosan as the free chain segment and Fe3O4@SiO2 stabilized emulsions together. The overall stabilization of the emulsion (Fe3O4@SiO2@chitosan as emulsifier) can be obtained at pH>2, and emulsion breaking is achieved at pH≈pKa condition.

An original route to develop an advanced class of microgel emulsifiers containing stimulable metallo-supramolecular instead of frozen covalent cross-links is reported. The poly(N-isopropylmethacrylamide) (PNiPMAM) chains of the microgel are connected by iron(II)-bis(terpyridine) coordination supramolecular complexes that can be cleaved on demand, leading to unique properties both at interfaces and in volume. The microgel synthesis is not demanding, and the characterization of its supramolecular structure can be precisely achieved by standard methods. Singularly, interfaces of an oil-in-water emulsion stabilized by the supramolecular particles can be triggered at the molecular scale by oxidation of Fe(II) to Fe(III), leading to emulsion breaking. In bulk, we show that a microgel dispersion can indeed be transformed into a polymer solution upon oxidation. Our study paves the way to the discovery of unusual microgel properties as our proof-of-concept can be extended to different supramolecular chemistry and architecture.

Nanocelluloses as a natural polysaccharide nanoparticle are widely used in preparing Pickering emulsions, but less involved in stimuli-responsive Pickering emulsions, due to complicated covalent modification. In this study, a novel pH-responsive emulsion system was prepared using nanocellulose hydrophobized in situ with a unique pH-responsive surfactant (MPAA) derived from rosin. The headgroup charge of MPAA could be reversibly switched between a cationic form (MPAAH) and an anionic form (MPAANa) via adjusting pH, both of which had excellent water solubility. In acidic condition (pH 4.0), the negatively charged nanocellulose could be hydrophobized in situ by absorbing the cationic MPAAH, and stable and high-viscosity Pickering emulsion gels were obtained. In alkaline condition (pH 10.0), the nanocellulose dispersed in aqueous phase and formed thick aqueous lamellae with negative charge, preventing the flocculation and coalescence of the negatively charged droplets, and oil-in-dispersion emulsions with smaller droplet size and low viscosity were formed. The corresponding properties, such as droplet size, stability, and viscosity could be easily controlled by changing pH. Importantly, MPAA and nanocellulose could be separated and reused multiple times. The work proposed an effective method to achieve multiple recycling and reuse of emulsifiers, showing good economic benefits and potential sustainable applications.

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The enormous demand for petroleum consumption has resulted in the shortage of fossil resources, prompting the need to explore unconventional reservoirs. Polyacrylamide emulsion drag reducers are capable of inhibiting the turbulence of fracturing fluids for enhancing the reservoir stimulation results, but the poor dissolution efficiency of polyacrylamide emulsion drag reducers is the primary limitation to their large-scale application. Here, a pH-responsive ionic liquid surfactant, oleic acid/cyclohexanediamine (HOA/HMDA), is synthesized by using oleic acid (HOA) and cyclohexanediamine (HMDA). HOA/HMDA shows a remarkable pH-responsive behavior due to the pH-induced deconstruction of the HOA/HMDA structure. Interestingly, the HOA/HMDA-stabilized monomer emulsion exhibits an obvious pH-induced emulsion structure transformation behavior. In addition, the HOA/HMDA-stabilized monomer emulsion possesses excellent dynamic and storage stability, supporting the inverse emulsion polymerization of the polymer P(AM/AMPS/AA). The obtained P(AM/AMPS/AA) polymer inverse emulsions maintained stability for 30 days. Our finding proposes that the structure of the P(AM/AMPS/AA) polymer inverse emulsions changes with pH stimulation, which is capable of facilitating the release of polymers. P(AM/AMPS/AA) is released from the P(AM/AMPS/AA) polymer inverse emulsions within 30 s at a pH value of 12.06, along with a drag reduction rate of 62.54%. Obviously, the HOA/HMDA-stabilized P(AM/AMPS/AA) polymer inverse emulsions eliminate the contradiction between the stability and release of polyacrylamide emulsion drag reducers, which is promising for meeting the demands of reservoir stimulation.

The membrane (PP–PPy–pHR) prepared in this paper automatically switches the wettability according to the change of pH to separate oil water emulsions. It has great potential for intelligent response in oil water separation.

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The growing demand for petroleum has intensified the pressure on conventional resources, driving exploration into unconventional reservoirs. Polyacrylamide (PAM) emulsion drag reducers can suppress fracturing fluid turbulence and improve reservoir stimulation, but their poor dissolution efficiency remains a key obstacle to widespread application. Herein, a pH-responsive Gemini surfactant (PA/OA) featuring a rigid piperazine ring as the hydrophilic headgroup was synthesized using piperazine (PA) and oleic acid (HOA). The PA/OA-stabilized monomer emulsion exhibited excellent stability for over 50 days at pH 7.0, enabling the successful inverse emulsion polymerization of PAM. The introduction of the piperazine ring and double hydrophobic tails enhances the molecular rigidity to promote a tight arrangement at the oil-water interface, thereby reinforcing the interfacial film and enhancing the interfacial activity. The surface activity of PA/OA varied at different pH conditions due to the interionic proton transfer between OA and PA. The pH-responsive ionic bonds in PA/OA facilitate rapid release of emulsion drag reducers, with most released within 30 s at pH = 10.0, and achieve a drag reduction rate of 68% at a concentration of 0.05 wt %. The PA/OA-stabilized emulsion effectively reconciled the conflict between long-term storage stability and rapid release performance encountered in single-chain-responsive surfactant systems.

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This study developed a pH and CO₂/N₂ dual-responsive Pickering emulsions stabilized by natural shellac nanoparticles (SNs), eliminating the need for complex synthetic stabilizers. Dynamic interfacial tension analysis reveals pH-dependent adsorption kinetics and interfacial rearrangement behavior of the SNs. Leveraging pH- or CO₂/N₂-regulated protonation-deprotonation transitions, the system could easily achieve O/W emulsion demulsification or emulsification while maintaining exceptional solvent universality and cycling stability (at least fifty cycles). The dual-responsive emulsion was further used as an interfacial catalytic platform for phospholipase D-mediated synthesis of phosphatidylserine (PS), which showed a 56 % increase in phosphatidylcholine conversion and a 98 % increase in PS yield compared with the traditional solvent system. The CO₂/N₂-triggered demulsification enabled green product/catalyst recovery, and the catalytic efficiency remains over 80 % of its original level after 5 cycles. These advancements originated from the synergistic stabilization of the nanoparticles with enzymes. This work establishes a zero-chemical-modification strategy for constructing intelligent emulsions from natural biomacromolecules, and expands its potential application in high value-added substance synthesis.

Emulsions, formed by dispersing a liquid into another immiscible one by virtue of emulsifiers, have been widely applied in commercial applications like foods, pharmaceuticals, cosmetics, and personal care, which always confront environmental and/or toxic questions due to emulsifiers' high dosage. Recently, a study on Pickering emulsions points out a solution to stable emulsions based on the costabilizing effect of colloidal particles, which focused on surface-active particles cooperating with oppositely charged ionic surfactants. Costabilized emulsions adopting a charge-similar ionic surfactant and particles were less studied. In this article, a hexane-in-water emulsion was prepared in use of a cationic surfactant cetyltrimethylammonium bromide (CTAB) with positively charged magnesium hydroxide (MH) nanosheets at low concentrations (10-5 M and 10-2 wt %, respectively). The emulsion is stable due to the synergy by CTAB and MH nanosheets, which functions in virtue of the electric repulsion by similarly charged particles, the mechanical shielding by MH nanosheets, and restrained water drainage in lamellae between droplets due to the gelation of MH nanosheets. Moreover, the emulsion is doubly switchable within emulsification/demulsification via convenient pH or ion manipulation, a mechanism based on the breakdown and rebuilding of the costabilizing synergy. Such dual-responsive emulsions show high potential for the delicate control of drug delivery, release, and biphasic biocatalysis applications.

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How to control the stability of oil-in-water (O/W) emulsions is one of the main topics for scientists working in colloidal systems. Recently, carbon dots (CDs) have received great interest as smart materials because of their excellent physicochemical properties and versatile applications. Herein, for the first time, advanced and switchable O/W emulsions are presented that are stabilized by the synergistic effect of cationic surfactant cetyltrimethylammonium bromide CTAB (emulsifier) and similarly charged CDs (stabilizer). In the formulated emulsion, the cationic surfactant molecules are adsorbed at the oil and water interface to decrease the interfacial tension and enrich the drops with a positive charge to ensure intensive electrostatic repulsions among them. On the contrary, cationic CDs are distributed in the water phase among the droplets to reduce the water secretion and prevent flocculation and droplet coalescence. The stabilizing effect is found to be universal for emulsions of a range of oil phases. Furthermore, the formulated emulsion is found to be switchable between "stable" and "unstable" modes by adding an equivalent of anionic surfactant sodium dodecyl benzene sulphonate (SDBS). The stabilized and switchable O/W emulsions are believed to have wide practical applications in water purification, pharmaceuticals, protein recognition, as well as catalysis.

Over 50% of the original oil in place (OOIP) is immobile or trapped in the reservoir. Therefore, today, more efficient methods have been introduced in the tertiary oil recovery sector as a scheme of enhanced oil recovery (EOR). Due to the decline of conventional hydrocarbon reserves, polymers are increasingly used in EOR methods, such as surfactant-polymer (SP) and alkaline-surfactant-polymer (ASP) flooding. SP flooding has a complex formulation and design, leading to undesirable phase separation if improperly mixed. Polymeric surfactants are a promising alternative to SP flooding. They consist of hydrophobic groups attached to hydrophilic polymers, which help to improve the mobility ratio and reduce interfacial tension (IFT). This paper examines the rheological and synthesis properties of a new polymeric surfactant produced through bond co-polymerization reaction using different hydrolyzed polyacrylamide (HPAM) ratios and a zwitterion hydrophobic group. The synthesized hydrophobically modified zwitterionic polyacrylamide (HMZPAM) was characterized by FTIR and HMNR analysis. HMZPAM performed better than other substances in IFT, viscosity, wettability, oil recovery, and resistance to different one and two-valence cations. The results indicate that HPAM reduced the IFT to 13.65, while HMZPAM reduced it to 0.441 mN/m. Wettability change evaluated on a rock carbonate/crude oil/HMZPAM system that changed the water-wet state of the primary oil-wet rock carbonate to strongly water-wet state as wettability change measurements showed a decrease in contact angle from 62.76 to 21.23 degree. Comparative studies on the effectiveness of HPAM and HMZPAM were also conducted according to the measurement of viscosity and shear rate in the presence of salt, which indicates the higher shear rate and viscosity of HMZPAM. Core flooding tests revealed that HMZPAM resulted in better additional recovery due to microscopic displacement, resulting in a total oil recovery of 84%, compared to 48% of residual oil saturation for HPAM. Also, salts decreased oil recovery in HPAM injection but increased oil recovery in HMZPAM injection.

This study examined how the concentration of asphaltene and divalent ions in various salinities affects the interfacial tension (IFT) between a model oil/brine using the pendant drop method. The oleic phase consisted of a mixture of toluene and n-heptane (heptol), to which asphaltene was added to investigate how asphaltene molecules affect the surface properties. The base fluid was prepared with a salinity of 40,000 ppm, and two additional solutions with concentrations of 4000 ppm (low salinity) and 80,000 ppm (high salinity) were created. The results revealed that increasing the concentration of asphaltene within certain salinity ranges led to a decrease in IFT. The lowest IFT was observed at the 40,000 ppm salinity level, indicating that at this optimal salinity, the maximum asphaltene concentration migrated to the heptol/brine interface, reducing the IFT from 23 mN/m to 16 mN/m. Additionally, a 0.5 % wt of asphaltene demonstrated a significant concentration of micellization of natural surfactants, suggesting that the interface was nearly saturated with asphaltene. Consequently, concentrations higher than this value did not significantly alter the IFT. In the final part of the study, the impact of divalent ions was investigated, revealing that as the concentration of Ca2+ ions increased up to fourfold, the IFT decreased to 15 mN/m, about 10 % less than the base case. This value represented the lowest IFT compared to Mg2+ and SO42−. Moreover, modeling the results indicated that the relaxation time decreased with increasing salinity, suggesting that higher salinity accelerated the process of asphaltene absorption at the interface.

Innovative methods to enhance oil recovery efficiency remain a high priority in the energy sector. This study investigates the potential of magnesium oxide (MgO) nanoparticles, both alone and with sodium dodecyl sulfate (SDS) surfactant, to improve oil recovery by reducing the interfacial tension (IFT) between oil and water. The research focuses on the physicochemical properties of MgO nanoparticles and their efficacy in IFT reduction, critical for Enhanced Oil Recovery (EOR). Preparation of MgO nanofluids was achieved using a Magnetic Stirrer and Sonics Vibracell VCX 750 Ultrasonic Homogenizer to ensure thorough mixing and dispersion. Characterization involved measuring density with Calibrated Density Bottles, dynamic and kinematic viscosity using a Falling Ball Viscometer, pH levels with an Electronic pH meter, and electric potential difference (mV). The Malvern Zetasizer Nano ZS assessed Zeta Potential (mV), Electric Conductivity (mS/cm), and Electrophoretic mobility (µmcm/Vs) for both the nanofluid and the surfactant-nanofluid systems. Paraffin oil served as the oil phase, with nanoparticle (NP) concentrations tested at 0.01, 0.03, 0.05, 0.1, and 0.5 wt%. The SDS concentration remained constant at 0.5 wt% throughout the study. We employed Pendant Drop Interfacial Tension measurements to evaluate the oil-water, oil-nanofluid, and oil-nanofluid + surfactant systems. Significant IFT reduction was observed—from 47.9 to 26.9 mN/m with a 0.1 wt% MgO nanofluid. Even a minimal concentration of 0.01 wt% MgO NP decreased notably from 47.9 to 41.8 mN/m. An IFT reduction of up to 70% was noted when MgO NPs were combined with SDS. This IFT reduction enhances oil mobility, suggesting the MgO-SDS system as an effective EOR technique. The study also recorded shifts in Zeta Potential from −2.54 to 3.45 mV and more alkaline pH levels from 8.4 to 10.8, indicating the nanofluid's altered surface charge and interaction dynamics. These physicochemical changes, aided by SDS, improved the dispersion and stability of MgO nanoparticles at the oil-water interface, thus boosting oil displacement efficiency. These findings highlight the potential of the MgO-SDS system as a cleaner alternative to traditional EOR methods that use toxic chemicals, offering economic benefits from enhanced reservoir performance. However, practical challenges remain, including ensuring nanoparticle stability and compatibility under diverse reservoir conditions, managing surfactant adsorption, and scaling up to field-level operations. Future research must address these issues while maintaining interdisciplinary collaboration and rigorous field studies. In conclusion, incorporating MgO nanoparticles and SDS surfactant presents a promising approach to improving oil recovery efficiency. Further investigation into its field application and economic feasibility is essential to gauge the potential of this technology in the energy industry.

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Interfacial tension (IFT) between surfactants and hydrocarbon is one of the important parameters in petroleum engineering to have a successful enhanced oil recovery (EOR) operation. Measuring IFT in the laboratory is time-consuming and costly. Since, the accurate estimation of IFT is of paramount significance, modeling with advanced intelligent techniques has been used as a proper alternative in recent years. In this study, the IFT values between surfactants and hydrocarbon were predicted using tree-based machine learning algorithms. Decision tree (DT), extra trees (ET), and gradient boosted regression trees (GBRT) were used to predict this parameter. For this purpose, 390 experimental data collected from previous studies were used to implement intelligent models. Temperature, normal alkane molecular weight, surfactant concentration, hydrophilic–lipophilic balance (HLB), and phase inversion temperature (PIT) were selected as inputs of models and independent variables. Also, the IFT between the surfactant solution and normal alkanes was selected as the output of the models and the dependent variable. Moreover, the implemented models were evaluated using statistical analyses and applied graphical methods. The results showed that DT, ET, and GBRT could predict the data with average absolute relative error values of 4.12%, 3.52%, and 2.71%, respectively. The R-squared of all implementation models is higher than 0.98, and for the best model, GBRT, it is 0.9939. Furthermore, sensitivity analysis using the Pearson approach was utilized to detect correlation coefficients of the input parameters. Based on this technique, the results of sensitivity analysis demonstrated that PIT, surfactant concentration, and HLB had the greatest effect on IFT, respectively. Finally, GBRT was statistically credited by the Leverage approach.

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The effects of sulfate salts under low and high salinity conditions and pH of 3.5–11 on interfacial tension (IFT) reduction and IL adsorption using resinous (RSO) and asphaltenic (8 wt/wt%) synthetic oils are investigated. The measurements showed the increasing effect of pH on the IFT of RSO/DW from 23.5 to 27.3 mN/m (pH = 3.5 → 7) in the first place and a reducing effect (0.4 mN/m) if pH = 7 → 11. Using a high concentration of 50,000 ppm for MgSO4, and Na2SO4 revealed an extensive IFT reduction for a pH value of 11 with the value of 0.20 mN/m for Na2SO4. The measured IFT values showed the significant impact of IL (500 ppm) on the IFT (minimum value of 0.01 mN/m for RSO/50,000 Na2SO4 + 500 ppm 1-decyl-3-methyl imidazolium triflate ([C10mim][TfO])) for pH = 11. The IL adsorption measurements showed the role of in-situ surfactant production (saponification process) on the 1-decyl-3-methyl imidazolium chloride ([C10mim][Cl]) and [C10mim][TfO] adsorption reduction from 3.67 to 2.33 and 4.21 to 3.34 mg IL/g rock, respectively. The performed core flooding experiments using the optimum chemical formulation showed the possibility of tertiary oil recovery with maximum oil recovery of 28.8% based on original oil in place in the presence of 500 ppm.