Search Results (37)

With the deepening of the green and low-carbon concept in the field of road engineering, the cold construction asphalt pavement technology has developed rapidly due to its advantages such as low energy consumption, low pollution, and convenient construction. The adhesion between emulsified asphalt and aggregates, as a core factor affecting the performance of cold-mixed mixtures and the lifespan of the pavement, has attracted much attention in terms of its mechanism of action and evaluation methods. However, at present, there are still many issues that need to be addressed in terms of the stability control of adhesion between emulsified asphalt and aggregates, the explanation of the microscopic mechanism, and the standardization of testing methods in complex environments. These problems restrict the further promotion and application of the cold construction technology. Based on this, this paper systematically analyzes the current development status, application scenarios, and future trends of the theory and testing methods of the adhesion between emulsified asphalt and aggregates by reviewing a large number of relevant studies. The research aims to provide theoretical support and practical references for the improvement of adhesion in the cold construction asphalt pavement technology. Research shows that in terms of the adhesion mechanism, the existing results have deeply analyzed the infiltration and demulsification adhesion process of emulsified asphalt on the surface of aggregates and clarified the key links of physical and chemical interactions, but the understanding of the microscopic interface behavior and molecular-scale mechanism is still insufficient. In terms of testing methods, although objective and subjective evaluation methods such as mechanical tensile tests, surface energy evaluation, and adhesion fatigue tests have been developed, the standardization of testing, data comparability, and practical engineering applicability still need to be optimized. Comprehensive analysis shows that the research on the adhesion between emulsified asphalt and aggregates is showing a trend from macroscopic to microscopic, from static to dynamic. There are challenges in predicting and controlling the adhesion performance under complex environments, as well as important opportunities for developing advanced characterization techniques and multiscale simulation methods. Full article

Shale oil, a major unconventional energy source with extensive global reserves, presents significant processing challenges due to the exceptional stability of its emulsions. Characterized by small droplet sizes and high interfacial film strength, these emulsions resist efficient treatment via conventional thermal-chemical or electrostatic dehydration. To address the difficulties in separation, unclear dehydration mechanisms, and inconsistent single-field (electric) performance, this study investigates dehydration using a novel electric–magnetic–ultrasonic coupling field system. Dehydration efficiency under an electric field alone increased with electric field strength, frequency, duration, and temperature. Magnetic or ultrasonic fields alone yielded negligible effects. Coupling an electric field with ultrasound enhanced efficiency, while adding a magnetic field to electricity provided no improvement and decreased efficiency with longer exposure or higher magnetic intensity. The multi-field coupling achieved significant demulsification. Both optimal dehydration performance and minimum energy consumption operating conditions were identified, capable of reducing shale oil water content below 0.5%. Full article

In this paper, the basic concept of surfactants as chemical additives and their diversified classification system are first expounded, laying a theoretical foundation for the subsequent study of their application in demulsification technology. Then, the specific application cases of various types of surfactants in the field of demulsification are deeply analyzed, and ways in which they achieve effective separation of emulsions through their unique physical and chemical properties are revealed. Further, the internal action mechanism of surfactant demulsifier, including how to destroy the stability of emulsion and promote the separation of oil and water phase, is systematically described. On this basis, the significant advantages of surfactant demulsifier compared with traditional methods are summarized, including high cost-effectiveness, high demulsifier efficiency, strong stability, wide adaptability, and easy operation. Finally, the development direction and challenges of surfactant demulsifier in the future are prospected. Full article

In the production process of the heavy oil industry, efficiently demulsifying water-in-heavy oil (W/HO) emulsions can effectively prevent the negative effects of emulsion corrosion on equipment, increase costs, reduce oil quality, and pollute the environment. Herein, polyether demulsifier complexes (PDC) were obtained by compounding fatty alcohol nonionic polyether (FAP) with perfluoropolyether (PFPEA, [CF₃O(CF₂CF₂O)_nCF₃]) through a simple physical blending method. The experimental results demonstrate that PDC exhibited outstanding demulsification performance for W/HO emulsions across varying temperatures: At 60 °C and 400 ppm dosage, PDC achieved complete dehydration (100%) within just 2 min, showing significantly faster demulsification kinetics compared to FAP and PFPEA. Even at the reduced temperature of 40 °C, PDC maintained effective demulsification capability, achieving complete phase separation within 6 min. These findings collectively establish PDC’s superior demulsification efficiency for W/HO emulsions, with particularly remarkable performance under challenging low-temperature conditions. Research on the demulsification mechanism indicates that PDC achieves efficient demulsification performance due to the synergistic effect the synergistic effect of FAP and PFPEA to effectively destroy the non-covalent bonds (hydrogen and π–π stacking) of interfacially active asphaltenes (IAA) at the oil–water interface, thereby achieving demulsification of W/HO emulsion. PDC with outstanding demulsification ability exhibits significant potential for practical applications in heavy crude oil–water emulsion treatment, and this work can provide insights for developing new composite demulsifiers for petroleum production. Full article

The primary extraction way for unconventional oil/gas resources is hydraulic fracturing to alter the reservoir for commercial production. However, hydraulic fracturing technology consumes a large amount of water, and the flowback water can easily be mixed with hydrocarbon substances to form emulsions. To achieve the recycling of water, it is necessary to develop an efficient continuous demulsification method for treating the flowback fluid. In this study, a composite filtration layer with superhydrophilic and superoleophilic properties was successfully prepared using water-based polyurethane as a binder. The g-C₃N₄ was used to improve the affinity of the filtration layer to water and oil. The diatomite and rice husk carbon were used as an adsorbent and a filter aid, respectively. The contact angles (CA) of both oil and water on the surface of the filtration layer were measured to be 0°. During the demulsification process, vacuum filtration was employed to increase the pressure difference across the filtration layer, thereby improving the treatment flux of flowback fluid. The experimental results showed that the filtration flux with the addition of rice husk charcoal increased from 160.58 L∙m⁻²∙h⁻¹ to 174.68 L∙m⁻²∙h⁻¹ compared to the filter layer without rice husk charcoal. Based on the composite filtration layer, the apparent demulsification efficiency exceeded 90.6% for various types of emulsion. The mechanism of demulsification was investigated by the molecular dynamics method. The results showed that the adsorption layer density of water molecules reached 1.5 g/cm³, and the adsorption layer density of oil molecules exceeded 2.5 g/cm³. The porous structure wall has a strong adsorption effect on both oil and water molecules, resulting in deformation and destruction of the oil–water interface, so that the dispersed phase is adsorbed and aggregated by the filter layer at the same time and permeates from the filter layer after reaching saturation, thus separating the two phases. Full article

This study aims to optimize the demulsification performance of a carbon quantum dot (CQD)-enhanced chemical demulsifier in industrial emulsions under thermal, mechanical, and thermomechanical effects. Experiments were conducted to assess treatments like organic treatment (OT), zeta potential modifier aqueous solution (ZPMAS), and acid treatment (9.25 wt.% HCl) at varying dosages, along with CQD–chemical mixtures optimized through a simplex-centroid mixture design (SCMD) to minimize basic sediment and water (BSW). Under the thermomechanical scenario, a system with 500 mg∙L⁻¹ CQDs and OT achieves 0.5% BSW and a droplet size of 63 nm, while an SCMD-optimized system (500 mg∙L⁻¹ CQDs + 380 mg∙L⁻¹ OT + 120 mg∙L⁻¹ ZPMAS) achieves 0% BSW and larger droplets (>70 nm). CQDs enhance demulsifiers by destabilizing water-in-oil (W/O) Pickering emulsions, leveraging their nanometric size, high surface area, thermal conductivity, and amphiphilicity, thanks to their hydrophobic core and surface hydrophilic groups (-OH, NH₂, -COOH). This research enhances the understanding of demulsification by employing green demulsifiers based on CQDs and provides a promising cost-efficient solution for breaking stable emulsions in the petroleum industry. It minimizes the use of complex and expensive active ingredients, achieving BSW values below 0.5%, the standard required for crude oil transport and sale, while also reducing separation equipment operation times, and improving overall process efficiency. Full article

The extraction and collection of crude oil will result in the formation of numerous complex emulsions, which will not only decrease crude oil production, raise the cost of extraction and storage, and worsen pipeline equipment loss, but also seriously pollute the environment because the oil in the emulsion can fill soil pores, lower the soil’s permeability to air and water, and create an oil film on the water’s surface to prevent air–water contact. At present, a variety of demulsification technologies have been developed, such as physical, chemical, biological and other new emulsion breaking techniques, but due to the large content of colloid and asphaltene in many crude oils, resulting in the increased stability of their emulsions and oil–water interfacial tension, interfacial film, interfacial charge, crude oil viscosity, dispersion, and natural surfactants have an impact on the stability of crude oil emulsions. Therefore, the development of efficient, widely applicable, and environmentally friendly demulsification technologies for crude oil emulsions remains an important research direction in the field of crude oil development and application. This paper will start from the formation, classification and hazards of crude oil emulsion, and comprehensively summarize the development and application of demulsification technologies of crude oil emulsion. The demulsification mechanism of crude oil emulsion is further analyzed, and the problems of crude oil demulsification are pointed out, so as to provide a theoretical basis and technical support for the development and application of crude oil demulsification technology in the future. Full article

The fouling of separation membranes has consistently been a primary factor contributing to the decline in membrane performance. Enhancing the surface hydrophilicity of the membrane proves to be an effective strategy in mitigating membrane fouling in water treatment processes. Zwitterionic polymers (containing an equimolar number of homogeneously distributed anionic and cationic groups on the polymer chains) have been used extensively as one of the best antifouling materials for surface modification. The conventional application of zwitterionic compounds as surface modifiers is intricate and inefficient, adding complexity and length to the membrane preparation process, particularly on an industrial scale. To overcome these limitations, zwitterionic polymer, directly used as a main material, is an effective method. In this work, a novel zwitterionic polymer (TB)—zwitterionic Tröger’s base (ZTB)—was synthesized by quaternizing Tröger’s base (TB) with 1,3-propane sultone. The obtained ZTB is blended with TB to fabricate microfiltration (MF) membranes via the vapor-induced phase separation (VIPS) process, offering a strategic solution for separating emulsified oily wastewater. Atomic force microscopy (AFM), scanning electron microscopy (SEM), water contact angle, and zeta potential measurements were employed to characterize the surface of ZTB/TB blended membranes, assessing surface morphology, charge, and hydrophilic/hydrophobic properties. The impact of varying ZTB levels on membrane surface morphology, hydrophilicity, water flux, and rejection were investigated. The results showed that an increase in ZTB content improved hydrophilicity and surface roughness, consequently enhancing water permeability. Due to the attraction of water vapor, the enrichment of zwitterionic segments was enriched, and a stable hydration layer was formed on the membrane surface. The hydration layer formed by zwitterions endowed the membrane with good antifouling properties. The proposed mechanism elucidates the membrane’s proficiency in demulsification and the reduction in irreversible fouling through the synergistic regulation of surface charge and hydrophilicity, facilitated by electrostatic repulsion and the formation of a hydration layer. The ZTB/TB blended membranes demonstrated superior efficiency in oil–water separation, achieving a maximum flux of 1897.63 LMH bar⁻¹ and an oil rejection rate as high as 99% in the oil–water emulsion separation process. This study reveals the migration behavior of the zwitterionic polymer in the membrane during the VIPS process. It enhances our comprehension of the antifouling mechanism of zwitterionic membranes and provides guidance for designing novel materials for antifouling membranes. Full article

The main objective of this study is to put forward effective schemes for alleviating reservoir choke caused by emulsification or Jamin’s effect using the dilution method by light crude oil, as well as sharply increased viscosity. In this study, water-in-heavy-oil (W/O) emulsions with varying water fractions were prepared with heavy oil from Bohai Bay, China. Mixtures of W/O emulsions and light crude oil samples (light oil and light heavy oil) with varied dilution ratio (1:9, 2:8, 3:7) are tested, respectively by the electron microscope and by the rheometer. W/O droplets’ distribution and viscosity variations are obtained to evaluate the emulsion stability and viscosity reduction effects by dilution. Results show that W/O droplets^, size distribution range increases with the increase of water fractions. W/O droplets with larger size tend to be broken first in the dilution process. Light oil could reduce emulsions’ viscosity more effectively than light heavy oil. Viscosity reduction mechanisms by dilution could be concluded as the synergistic effects of dissolving heavy components and weakening oil–water film stability. Therefore, light oil is suggested as the optimal one for solving formation plugging. The poor performance of Richardson model is related to the re-emulsification between free water and crude oil favored by light heavy oil, and demulsification favored by light oil. The modified model shows a significant improvement in prediction accuracy, especially for W/O emulsions with large water fractions. This study demonstrates a promising and practical strategy of solving heavy oil well shutdown problems and viscosity increasing by injecting light crude oil in the thermal stimulation. Full article

The reversible emulsion drilling fluid system combines the advantages of both oil-based and water-based drilling fluids, which can achieve ideal results in different stages of drilling and completion, and the system can be reused to effectively reduce costs. However, the research on reversible emulsions mainly focuses on the development of new reversible emulsifiers, while the specific phase transformation mechanism of reversible emulsion systems is still unclear. In this paper, a stable reversible emulsion was prepared using the reversible emulsifier DMOB as a raw material, and the reversible emulsion performance of the alkali response from the O/W emulsion phase to the W/O emulsion was studied. The microstructure of reversible emulsions was studied by a microscope, a cryogenic transmission electron microscopy, and a laser particle size analyzer. The changes in macroscopic properties of reversible emulsions in the process of alkali conversion were studied by pH, conductivity, demulsification voltage, static stability, viscosity, rheology, and other indicators, and the conversion mechanism of reversible emulsions from O/W emulsion ⟶ bicontinuous structure ⟶ O/W/O emulsion ⟶ W/O emulsion was clarified. The details are as follows: in the first stage, when the amount of NaOH ≤ 0.43 vol.%, the overall particle size of the emulsion decreases first and then increases with the increase in NaOH dosage. In the second stage, when the amount of NaOH was 0.45 vol.%, a double continuous structure was formed inside the emulsion. In the third stage, when the amount of NaOH is 0.48 vol.%, the O/W/O emulsion is formed, and with the increase in stirring time, the internal oil droplets gradually accumulate and are discharged from the water droplets, and finally, the W/O emulsion is formed. In the fourth stage, when the dosage of 0.50 vol.% ≤ NaOH ≤ 5.00 vol.%, the W/O emulsion was formed, and with the increase of NaOH dosage, the structure and compactness between water droplets increased first and then decreased. In the whole process, with the increase in the amount of NaOH solution, the total particle size of the emulsion first decreased and then increased. Full article

Cement-emulsified asphalt (CEA) has been widely used in slab ballastless track and asphalt pavement cold recycling projects because of its high stiffness and toughness. In CEA material, emulsifiers and asphalt affect the cement’s hydration process and microstructure. Thus, to further investigate the effects of anionic emulsifiers (AEs) and anionic emulsified asphalt (AEA) with different demulsification rates on the hydration process and microstructure of cement, two types of AE (rapid-setting and slow-setting) and their corresponding AEA were used to prepare modified cement pastes. First, it was confirmed that the AEs and AEA delayed cement hydration by measuring the setting time, X-ray diffraction (XRD) patterns, and electrical resistivity of the cement paste. Then, the microstructure of the cement paste was determined with mercury intrusion porosimetry (MIP) and a scanning electron microscope (SEM), and it was found that AEs and AEA have varying degrees of inhibitory effects on the formation of the cement paste microstructure. Finally, based on the energy dispersive spectrometer (EDS) element content of the cement paste and Fourier transform infrared spectroscopy (FTIR) on the two AEs, the inhibition mechanism of AE and AEA with different demulsifier rates on the cement hydration process was analyzed. The experimental results showed that both AEs and AEA delayed the hydration process of cement to varying degrees and altered the microstructure of cement, and slow setting anionic emulsified asphalt (SAEA) had the greatest impact on the hydration process and microstructure of cement. Compared to pure cement paste, the initial setting time of cement paste mixed with SAEA was delayed by 73.9%, and the final setting time was delayed by 66.7%. After adding SAEA, the most probable aperture of the cement paste increased from 62.50 nm to 71.19 nm after one day of hydration. Due to the fact that there were more carboxyl groups with negative charges, more -COO⁻ was adsorbed onto the surface of cement particles in the slow-cracking anionic emulsifier (SAE); compared with the rapid-setting anionic emulsifier (RAE) and the rapid-setting anionic emulsified asphalt (RAEA), the SAE and the SAEA had a stronger delaying effect on the hydration reaction of cement. Full article

Organic amine and nanosilica were combined to create a nano-demulsifier, which was employed in the oil–water separation process of a condensate emulsion. The nano-demulsifier has the structure of hyperbranched polymers and the skeleton structure of hyperbranched nanomaterials, and displays the demulsification impact of organic amine polymers as well as the synergistic effect of nanomaterials. This nano-demulsifier has the potential to drastically reduce the quantity of condensate demulsifiers utilized in the gathering station. The dehydration rate of the condensate lotion in the gas gathering station can reach more than 95% only at a concentration of 1.0 wt.%. Its application can significantly increase the separation efficiency of the condensate emulsion as well as the quality of condensate oil. It has a positive impact on cost reduction and efficiency in gas well production. The mechanism of action of the demulsifier was also studied, and the results show that the demulsifier is a phase reverse demulsifier. Full article

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. Full article

In the heavy petroleum industry, the development of efficient demulsifiers for the effective breaking of interfacially active asphaltenes (IAA)-stabilized water-in-heavy oil (W/HO) emulsions is a highly attractive but challenging goal. Herein, a novel nitrogen and oxygen containing demulsifier (JXGZ) with strong hydrogen bonding has been successfully synthesized through combining esterification, polymerization and amidation. Bottle tests indicated that JXGZ is effectual in quickly demulsifying the IAA-stabilized W/HO emulsions; complete dehydration (100%) to the emulsions could be achieved in 4 min at 55 °C using 400 ppm of JXGZ. In addition, the effects of demulsifier concentration, temperature and time on the demulsification performance of JXGZ are systematically analyzed. Demulsification mechanisms reveal that the excellent demulsification performance of JXGZ is attributed to the strong hydrogen bonding between JXGZ and water molecules (dual swords synergistic effect under hydrogen bond reconstruction). The interaction of the “dual swords synergistic effect” generated by two types of hydrogen bonds can quickly break the non-covalent interaction force (π-π stacking, Van der Waals force, hydrogen bonds) of IAA at the heavy oil–water interface, quickly promote the aggregation and coalescence of water molecules and finally achieve the demulsification of W/HO emulsions. These findings indicate that the JXGZ demulsifier shows engineering application prospects in the demulsification of heavy oil–water emulsions, and this work provides the key information for developing more efficient chemical demulsifiers suitable for large-scale industrial applications. Full article

In this study, the internal relationships among oil bodies (OBs), the protein–phospholipid interactions in aqueous phase, oil–water interface behavior, and the stability of reconstituted OBs were analyzed from the bulk phase, interface, and macro perspectives, and the stability mechanism of OBs was discussed. OB proteins and phospholipids were combined through hydrophobic and electrostatic interactions, resulting in the stretching of protein conformation. OB proteins and phospholipids act synergistically to increase interface pressure and the rate of increase in interface pressure with relatively stable elastic behavior, which is beneficial to the formation and stability of interfacial films. When OBs were reconstituted by an OB protein–phospholipid complex system, phospholipids bound to OB proteins through hydrophobic and electrostatic interactions. OB proteins and phospholipids uniformly covered the oil droplet surface of reconstituted OBs to form a stable interfacial film, which maintained the stability of OBs. The addition of phospholipids significantly reduced the particle size of OBs prepared by OB proteins in a dose-dependent manner, and particle size decreased with the increase in phospholipid content (p < 0.05). Phospholipids increased the net surface charge, enhanced electrostatic repulsion, and improved the physicochemical stability of reconstituted OBs. The stability mechanism elucidated in this study provides a theoretical basis for the demulsification of peanut OBs. Full article