Demulsification techniques of water-in-oil and oil-in-water emulsions in petroleum industry

Treatment of oil-based drilling cuttings using the demulsification separation-Fenton oxidation method

In this study, demulsification separation-Fenton oxidation technology was employed as a combined technology to treat total petroleum hydrocarbons (TPH) in oil-based drill cuttings (OBDC). Batch experiments were carried out to optimize the technology parameter. Under the optimal condition, 70% and 51% TPH removal rate was obtained for demulsification technology and Fenton oxidation technology, respectively. Eighty-five percent of TPH removal rate was obtained using combination technology of demulsification separation and Fenton oxidation. Multiple characterizations were used to analyze the physical and chemical properties of treated OBDC. The result of XRD pattern indicated the combination technology had no obvious effect for structure phase of OBDC. The results of FTIR, GC-MS, TG-DTG and SEM were used to characterize the treated OBDC. This paper provides an efficient and feasible combined technology for OBDC treatment, which expands a new strategy for the removal of TPH from solid waste.

Surface Charge Regulation of MIL-100(Fe) by Anion Exchange for Demulsifying the Cationic Surfactant-Stabilized O/W Emulsion

Demulsifying ionic surfactant-stabilized emulsions remains an emerging issue due to the stringent electrostatic barriers. In this work, a phosphate-mediated anion exchange strategy was proposed to fabricate a metal-organic framework, MIL-100(Fe), with adjustable surface charge for effective demulsification toward a cationic surfactant-stabilized emulsion. By adjusting the pH of the phosphate precursor solution, the surface charge of MIL-100(Fe) can be fine-tuned. At pH 3.0, the phosphate-exchanged MIL-100(Fe) with the zeta potential decreasing from 21.4 to 6.1 mV exhibited a significant enhancement of the demulsification efficiency (DE) from 35 to 91%. Further elevating the pH to 9.0 results in the zeta potential of the phosphate-exchanged MIL-100(Fe) to be reversed to -2.0 mV, and the DE can be optimized to 96% within 5 min. The demulsification mechanism was systematically explored based on the zeta potential, distribution of the surfactant, viscoelastic modulus evaluation, and morphological characterization of the emulsion in combination with monitoring of the dynamics process of demulsification. It was found that the phosphate-exchanged MIL-100(Fe) captured by the emulsion can lead to the release of the surfactant and heterogenization of the interfacial film, causing the elasticity of the emulsion to decrease and the irreversible deformation of emulsion droplets. Consequently, the destabilized emulsion could be subjected to the effective demulsification either by the fusion pathway mediated by the phosphate-exchanged MIL-100(Fe) or direct rupture. This work emphasized a facile and promising approach to deal with the cationic surfactant-emulsified oily wastewater and disclosed the fundamental demulsification process.

Demulsification Treatment of Spent Metalworking Fluids by Metal Cations: The Synergistic Effect and Efficiency Evaluation

In this paper, various metal ions were utilized for the demulsification of spent metalworking fluids discharged from an automobile parts workshop. Five types of metal ions, i.e., Fe3+, Al3+, Fe2+, Ca2+ and Mg2+, combined with coagulant were systematically evaluated, and the synergistic effect as well as the optimum operating conditions were studied. The results indicated that the Ca2+ as well Mg2+ possessed hardly efficiency for the demulsification, on the contrary, Fe2+ reduced the yield of the by-product sludge and lowered the SV30 ratio, and Al3+ boosted the CODCr removal. Furthermore, Fe3+ and Al3+ had a significant synergistic effect to achieve a better transmittance and a higher CODCr/SV30 ratio which revealed that more CODCr was removed, as well as less by-product sludge was generated. For a better demulsification of spent metalworking fluids, the optimum operating conditions were gathered as follows: the dosage of metal ions was 0.08 mol/L with Al3+:Fe3+ ratio was 1.5:1, the reaction pH was 6.00, the reaction time was 18.00 min and the temperature was 323.00 K. Based on this, the CODCr removal, the SV30 ratio and the transmittance and CODCr/SV30 ratio of the spent metalworking fluids were 80.21%, 40.00%, 95.20% and 128.33 mg/mL, respectively. This combined metal ion demulsification method possessed an advantageous minimization of spent metalworking fluids, which greatly benefited the automobile parts workshops in cutting down the operating cost in environmental protection.

Trending approaches on demulsification of crude oil in the petroleum industry

The complicated nature of crude oil emulsions is part of the major setbacks associated with the postulation of methods for phase separation and demulsification in the oil industry. Despite the increasing efforts in generating efficient and dependable demulsification methods, the majority of emulsions cannot be shattered in reduced times. This review examines the trending techniques of crude oil demulsification in the petroleum industry. Several approaches have been examined to discover the best method of demulsification. Hence, this reports reviewed the past studies on the emulsion, formation of oil emulsions, methods of demulsification, characteristics of demulsifier, mechanism of demulsification, kinetics in demulsification, operating parameters influencing the demulsification processes, the structure of demulsifier, and formulations that are involved in the demulsification. The formulations of crude oil demulsification have been investigated to unveil adequate demulsifiers for crude oil. Therefore, demulsification approaches have several applications due to wider varieties of crude oil, separation equipment, brines, chemical demulsifiers, the method in which demulsifiers is been formulated, and product specifications.

Application of interval-valued Pythagorean fuzzy VIKOR approach for petroleum sludge treatment technology evaluation and selection

Petroleum sludge is produced during oilfield development and production and can negatively impact the production area and surrounding environment. With increasing attention to the environmental protection of oilfields, finding an energy-efficient, environmentally sound, cost-effective and socially acceptable sludge treatment method is crucial to the sustainable development of oil companies. However, there are several problems in the selection process: ① there is no effective index system for the evaluation of treatment technologies; ② there is data uncertainty and loss of information; ③ experts in the field often make one-sided decisions; and ④ the common decision models fail to balance the general effect and local dominance of a treatment technology. This study is innovative in the following aspects: ① a decision index system of petroleum sludge treatment technology is established; ② the interval-valued Pythagorean fuzzy set effectively managed data uncertainty and loss of information; ③ the redundancy-based expert weighting method is used to avoid one-sided decisions; and ④ using the basic ideas of the VIKOR model to balance the general effect and local dominance of a technology. Example verification proved the effectiveness of this method and a sensitivity analysis showed the results were reliable. Finally, this study compared the results obtained by three other similar methods, and comparative analysis demonstrated that this approach effectively evaluated and selected petroleum sludge treatment technologies. This study improves the rationality of petroleum sludge treatment technology selection and provides a necessary reference for the selection of treatment technology for other petroleum pollutants.

Mechanism of separation and removal of water from oily sludge using liquid dimethyl ether to dissolve hydrocarbons

The effective disposal of oily sludge generated from the petroleum industry has received increasing concern. The primary difficulty for the reduction and resource utilization of oily sludge is dewatering. Therefore, finding an efficient and energy-saving dewatering technology is an urgent need for the treatment of oily sludge. In this study, an innovative developed method using liquefied dimethyl ether (L-DME) for dewatering is employed to deal with oily sludge for the first time. Oily sludge from a refinery was used to conduct experiments in sequencing dissolution-separation reactors. Changes in the dehydration rate, oil recovery, group components (hydrocarbon series of petroleum, including saturates, aromatics, resins and asphaltenes) at different extraction time, temperatures and L-DME additions were measured. The results revealed that L-DME removed 90% of the water and recovered 40% of the oil, which was an amazing dehydration effect for oily sludge. The water-binding form of oily sludge is different from sewage sludge and other biomass and the water in oily sludge is in a stable water-in-oil (W/O) suspension emulsified state. L-DME was mixed with semi-colloidal like oily sludge to break the structure of the water-in-oil emulsion, making the mixture into a solid-liquid two phase substances that were easy to separate, thus achieving a high degree of separation of water. The dissolution of saturated hydrocarbons, aromatic hydrocarbons, and small amounts of colloid by L-DME played an important auxiliary role in water removal.

Influence of oil droplet behavior in electrochemical micromembrane cells on treating oil/water emulsions with low-salt concentrations

Although flow-through electrode has demonstrated its potential in treating oily wastewater, few studies noted influence of oil droplet behavior on treating oil/water emulsions. In order to explore the influence of oil droplet behavior in a flow-through electrode cell on treating oil/water emulsions with low-salt concentrations, an electrochemical micromembrane cell was applied to treat oil/water emulsions with 0-0.8 g/L NaCl. High chemical oxygen demand (COD) reduction (80-90%) was obtained in treating Sodium dodecylbenzene sulfonate (SDBS) or Tween 80 emulsion by flow-through electrode, while the later had the higher permeate flux (900 mL/min around). The low salt concentration (0.5 g/L NaCl) achieved high COD reduction (87%) and good permeate flux (600 mL/min). Observations using optical microscopy revealed severe deformation of the shape of the charged oil droplet at the flow-through electrode interface. The wetting of oil droplets at the electrode interface occurred when the membrane acted as an anode, which resulted in flow-through electrode fouling, and subsequently, the reduction in permeate flux and treatment efficiency. The results of this study offer an attractive option when using flow-through electrode to treat oil-in-water emulsions under low-salinity conditions.

A review of the interfacial stability mechanism of aging oily sludge: Heavy components, inorganic particles, and their synergism

Oily sludge is widely produced in the processes of petroleum exploitation, storage, transportation, and refining, and becomes more stable during aging. The interfacial stability of aging oily sludge hinders the recovery and disposal of oil resources. This review summarizes the interfacial film stability of aging oily sludge, which occurs through the formation of viscoelastic and rigid bilayer interfacial films between heavy components (asphaltenes and resins) and inorganic particles. The bilayer interfacial films enhance interfacial film strength and hinder the aggregation of droplets, contributing to the formation of a stable and high-viscosity oil-water-solid three-phase mixture. Recent demulsification technologies for reducing the stability of interfacial films have been classified as follows: removing heavy components, changing asphaltene aggregate structure, and reducing inorganic particle content. More efficient demulsification technologies are expected to be developed by deeply analyzing the microstructure and interfacial properties of asphaltenes and resins, as well as comprehensively studying the complex interactions among various components. This review constructs a bridge between the stability mechanism and the corresponding destabilization methods, which would promote future studies in aging oily sludge treatment.

Stability Dynamic Characteristic of Oil-in-Water Emulsion from Alkali-Surfactant-Polymer Flooding

The relationship model between the droplet lifetime and interface properties is established to characterize the stability of oil droplets, and then, the influence of the alkali-surfactant-polymer (ASP) concentration on the lifetime is analyzed by theoretical calculations. The stability dynamic characteristics of oil-in-water (O/W) emulsions from ASP flooding were evaluated using the emulsion stability model (Civan model) based on two-phase separation. The effect of ASP on dynamic characteristics of the emulsion was explored by analyzing film strength qualitatively and measuring interfacial tension and ζ potential. The results showed that the Civan model was suitable to evaluate the stability of the O/W emulsion and to obtain the corresponding dynamic characteristics. The O/W emulsions became more stable with the increasing alkali concentration first at a low alkali concentration (c _NaOH < 200 mg/L) and then became less stable with the increasing alkali concentration at a high alkali concentration (c _NaOH > 200 mg/L). The stabilities of O/W emulsions were improved with the increasing concentrations of the surfactant and polymer. The mechanism of stabilization of the O/W emulsion by ASP is as follows. The surface-active substances formed by the reaction of alkali and acidic substances in the oil phase, together with surfactants, adsorb at the oil-water interface, reducing the interfacial tension and increasing the strength of the oil-water interface film. The polymer only increases the strength of the interface film by increasing the viscoelasticity of the oil-water interface film.

Enhancing Demulsification Performance for Oil-Water Separation through Encapsulating Ionic Liquids in the Pore of MIL-100(Fe)

Emulsion poses a greater challenge for the remediation of oily wastewater, which can be effectively resolved by the metal-organic framework of MIL-100(Fe). The formula Fe₃O(H₂O)₂(OH) (BTC)₂ pronounces that MIL-100(Fe) suffers from an intrinsic defect of less charged atoms, which limits its demulsification performance for oil-water separation. Herein, cations of the ionic liquid (1-allyl-3-methylimidazolium, Amim⁺) were encapsulated in the micropore of MIL-100(Fe) in situ to increase the positive charge density of MIL-100(Fe). Zeta potential demonstrated that the encapsulation of Amim⁺ increased the positive charge amount of MIL-100(Fe). N₂ probe isothermal adsorption/desorption and spectral measurements (X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy, and attenuated total-reflectance infrared spectroscopy) revealed the host-guest interactions of π···Fe complexation and π···cation electrostatic attraction between Amim⁺ and MIL-100(Fe) for the composite materials. Amim⁺ encapsulation greatly enhanced the demulsification performance of MIL-100(Fe) for oil-in-water (O/W) emulsion stabilized by sodium dodecyl sulfate. Amim⁺-encapsulated MIL-100(Fe) with an Amim⁺/Fe³⁺ molar ratio of 1:1 [Amim@MIL-100(Fe)-3:3] showed a demulsification efficiency (DE) of 94% within 30 s, compared with MIL-100(Fe) within 30 min. The maximum DE of Amim@MIL-100(Fe)-3:3 was found to be more than 98% within 5 min. The DE lost by MIL-100(Fe) at the third run decreased from 36 to 17% after encapsulating Amim⁺. The analysis of surface charge and interfacial tension implied a demulsification mechanism of capturing-fusion, which could be promoted by the greater electrostatic attraction. Finally, the role of Amim⁺ on the outstanding demulsification performance by Amim⁺-encapsulated MIL-100(Fe) could be explained by the enhanced nonbonded interaction of electrostatic attraction and van der Waals based on the molecular dynamics simulation.

Synthesis of MRGO Nanocomposites as a Potential Photocatalytic Demulsifier for Crude Oil-in-Water Emulsion

Oil-in-water (O/W) emulsion has been a major concern for the petroleum industry. A cost-effective magnetite-reduced graphene oxide (MRGO) nanocomposite was synthesized to study the demulsification process of emulsion using said nanocomposite under solar illumination. Characterization data show that the magnetite was successfully deposited on reduced graphene oxide through redox reaction at varying loading amounts of magnetite. Demulsification of the O/W emulsion using MRGO nanocomposite shows that in general the demulsification efficiency was dependent on the loading amount of Fe3O4 on the RGO sheet. It was proposed that the surfactant hydroxyl groups have an affinity towards Fe3O4, which the loading amount was directly proportionate to available active site in Fe3O4. As the loading amount increases, charge recombination centers on the RGO sheet would increase, effectively affecting the charge distribution within MRGO structure.

Synthesis and Characterization of a Novel Multibranched Block Polyether Demulsifier by Polymerization

Various flooding technologies were applied in the middle and late stages of the oilfield, which made the heavy oil emulsion receive much concern because of its high stability and separation difficulty. In our paper, alcohol molecules were used as initiators and multibranched block copolymers were synthesized through open-loop polymerization technology. A variety of novel modified block polyether demulsifiers with demulsification activity were finally synthesized through water-soluble modification and oil-soluble modification, which achieved efficient demulsification of heavy oil emulsions. Hydrophile-lipophile balance (HLB) values and surface tension were used to characterize demulsifiers. In addition, their demulsification efficiency was evaluated by measuring the amount of dehydration in the separated heavy oil emulsion experiments. The experimental results showed that within 5 h, the demulsification effect of the water-soluble demulsifier is better than that of the oil-soluble demulsifier. When the HLB value of the demulsifier reaches a certain value, the dehydration rate and the demulsification effect reach the highest point. When the amount of demulsifier is 50 μg/g and the demulsification temperature is 85 °C, the dehydration rate of the water-soluble demulsifier X-6 reached 91%, the water quality was clear, and the demulsification effect reached its peak. This work will provide a novel and efficient demulsifier for demulsification and dehydration of heavy oil emulsions.

Surfactant-Enhanced Spontaneous Emulsification Near the Crude Oil-Water Interface

Spontaneous emulsification near the oil-water interface and destabilization of water-in-oil emulsions in the bulk oil phase may affect the efficiency of improved oil recovery. In this study, we investigate the effect of a demulsifier surfactant on spontaneous emulsification near the oil-aqueous phase interface and in the bulk oil phase through imaging. The results show that pronounced spontaneous emulsions may form near the oil-aqueous phase interfaces. The mechanism of diffusion and stranding is believed to dominate spontaneous emulsification. A demulsifier surfactant, which has been used for demulsification of water-in-oil emulsions in the bulk oil phase, is found to enhance spontaneous emulsification near the oil-water interface. The diffusive flux of water through the interface can be enhanced if the demulsifier is added into the aqueous phase, in which the demulsifier may act as a carrier. It can generate a region of local supersaturation combined with hydrated asphaltenes and result in faster and stronger spontaneous emulsification. We also investigate the effect of a viscosifier polymer on emulsion formation. The polymer is used to improve sweep efficiency in oil displacement. In this work, we show that it can inhibit emulsification in the bulk oil phase, but its effect on spontaneous emulsification near the interface is not pronounced.

A novel biodemulsifier of Bacillus mojavensis XH1 - Oxalate decarboxylase with the potential for demulsification of oilfield emulsion

In recent years, special attention has been devoted to biodemulsifiers as a new type of environment-friendly demulsifiers. A novel biodemulsifying oxalate decarboxylase (OxdC) secreted by Bacillus mojavensis XH1 is reported in the present study. A genome-wide comparison showed that strains with high demulsification efficiencies all possess alkane degradation genes. An analysis of the differentially expressed genes and proteins induced by different substrates showed that OxdC secreted by XH1 was an effective demulsifier. Moreover, the demulsification ability was verified by prokaryotic gene expression, knockout and complementation analyses. OxdC from XH1 exhibited a strong demulsification capacity and significantly outperformed the model protein Bacillus subtilis 168 OxdC (Yvrk), which shared a high amino acid similarity but showed limited demulsification ability. Based on a comparison of the structural characteristics, the hydrophobic amino acids on the surface of OxdC were identified as a key factor driving the favorable demulsification activity of XH1. The metabolic pathways of XH1 used liquid paraffin and glucose as substrates, illustrating that hydrocarbons are necessary for biodemulsifier secretion. The present study provides new insight into the application of OxdC as an additional genetic resource in biodemulsification.

Experimental Study on the Performance of a Novel Compact Electrostatic Coalescer with Helical Electrodes

As most of the light and easy oil fields have been produced or are nearing their end-life, the emulsion stability is enhanced and water cut is increasing in produced fluid which have brought challenges to oil–water separation in onshore and offshore production trains. The conventional solution to these challenges includes a combination of higher chemical dosages, larger vessels and more separation stages, which often demands increased energy consumption, higher operating costs and larger space for the production facility. It is not always feasible to address the issues by conventional means, especially for the separation process on offshore platforms. Electrostatic coalescence is an effective method to achieve demulsification and accelerate the oil–water separation process. In this paper, a novel compact electrostatic coalescer with helical electrodes was developed and its performance on treatment of water-in-oil emulsions was investigated by experiments. Focused beam reflectance measurement (FBRM) was used to make real-time online measurements of water droplet sizes in the emulsion. The average water droplet diameters and number of droplets within a certain size range are set as indicators for evaluating the effect of coalescence. We investigated the effect of electric field strength, frequency, water content and fluid velocity on the performance of coalescence. The experimental results showed that increasing the electric field strength could obviously contribute to the growth of small water droplets and coalescence. The extreme value of electric field strength achieved in the high-frequency electric field was much higher than that in the power-frequency (50 Hz) electric field, which can better promote the growth of water droplets. The initial average diameters of water droplets increase with higher water content. The rate of increment in the electric field was also increased. Its performance was compared with that of the plate electrodes to further verify the advantages of enhancing electrostatic coalescence and demulsification with helical electrodes. The research results can provide guidance for the optimization and performance improvement of a compact electrocoalescer.

A critical review on energy recovery and non-hazardous disposal of oily sludge from petroleum industry by pyrolysis

This review systematically reports the pyrolysis of oily sludge (OS) from petroleum industry in regards to its dual features of the energy recovery potential and the environmental risks. The petroleum hydrocarbons are the nonbiodegradable fractions in OS that possess hazardous properties, i.e. ignitability and toxicity. Besides, complicated hazardous elements (i.e. N, S and Cl) and heavy metals inherently existing in OS further aggravate the environmental risks. However, the high oil content and heating value of OS contribute to its huge energy resource potential. Considering the energy demand and the environmental pressure, the ultimate purposes of the OS management are to enhance the oil recovery efficiency to minimize the oil content as well as to stabilize the hazardous elements and heavy metals into the solid residue. Among various OS management technologies, pyrolysis is the most suitable approach to reach both targets. In this review paper, the pyrolysis principle, the kinetics and the product distribution in three-phases are discussed firstly. Then the effects of operating parameters of the pyrolysis process on the quality and the application potential of the three-phase products, as well as the hazardous element distribution are discussed. To further solve the dominant concerns, such as the oil content in the solid residue, the pyrolytic oil quality and the migration of hazardous elements and heavy metals, the potentials of the catalytic pyrolysis and the co-pyrolysis with additives are also summarized. Also, the typical pyrolysis reactors are then presented. From the perspective of the energy efficiency and the non-hazardous disposal, the integrated technology combining the pyrolysis and the combustion for the OS management is recommended. Finally, the remaining challenges of OS pyrolysis encountered in the research and the industrial application are discussed and the related outlooks are itemized.

Photocatalytic demulsification of oil/water emulsions containing nonionic surfactant

Separation of oil-water (OW) emulsions is investigated using a photocatalytic demulsification approach. Experiments were conducted using two types of photocatalysts, namely, ZnO and TiO₂. The emulsion samples were prepared with oil to water ratios of 1:3, 1:1, and 3:1 and using nonionic surfactant Tween 20 as an emulsifier. The demulsification efficiency was determined using a direct time varying phase separation measurement, while dynamic light scattering (DLS) and microscope imaging (MI) were used to determine the change in emulsion droplets size. The investigation results showed that all the emulsions were destabilized and separated within 30-90 min with demulsification efficiency that ranged from 38 to 90%. On the other hand, untreated control samples remained stable with no phase separation for more than 24 h. For most of the studied experimental conditions, TiO₂ nanoparticles gave better demulsification results than ZnO. Modeling of the batch demulsification kinetics for both systems agreed satisfactorily with the experimental measurements. This could allow its further extension towards design of continuous processes for potential implementation in treatment of industrial oily wastewaters.

Overview of recent developments of resource recovery from wastewater via electrochemistry-based technologies

As the rapid increase of the worldwide population, recovering valuable resources from wastewater have attracted more and more attention by governments and academia. Electrochemical technologies have been extensively investigated over the past three decades to purify wastewater. However, the application of these technologies for resource recovery from wastewater has just attracted limited attention. In this review, the recent (2010-2020) electrochemical technologies for resource recovery from wastewater are summarized and discussed for the first time. Fundamentals of typical electrochemical technologies are firstly summarized and analyzed, followed by the specific examples of electrochemical resource recovery technologies for different purposes. Based on the fundamentals of electrochemical reactions and without the addition of chemical agents, metallic ions, nutrients, sulfur, hydrogen and chemical compounds can be effectively recovered by means of electrochemical reduction, electrochemical induced precipitation, electrochemical stripping, electrochemical oxidation and membrane-based electrochemical processes, etc. Pros and cons of each electrochemical technology in practical applications are discussed and analyzed. Single-step electrochemical process seems ineffectively to recover valuable resources from the wastewater with complicated constituents. Multiple-step processes or integrated with biological and membrane-based technologies are essential to improve the performance and purity of products. Consequently, this review attempts to offer in-depth insights into the developments of next-generation of electrochemical technologies to minimize energy consumption, boost recovery efficiency and realize the commercial application.

New Amphiphilic Tricationic Imidazolium and Pyridinium Ionic Liquids for Demulsification of Arabic Heavy Crude Oil Brine Emulsions

Preparation of new green oilfield chemicals based on ionic liquids (ILs) having higher demulsification efficiency to solve the heavy crude oil brine water emulsions became a target in the petroleum research studies and industry. In the present work, the combination of pyridinium, imidazolium, and hydrophilic or hydrophobic moieties in the chemical structure of ILs has been investigated to improve the surface properties of ILs in both bulk solution and interfaces. Aminopyridine was quaternized with cetylbromide and condensed with glyoxal and 4-hydroxybenzaldehyde in acetic acid to prepare imidazolium-pyridinium bromide acetate ionic liquid (IPy-IL). The phenol group of IPy-IL was etherified with tetraethylene glycol to alter its amphiphilicity and synthesize new amphiphiles (AIPy-IL). Their chemical structure, thermal characteristics, and stabilities were characterized. Their aqueous solution performance in seawater was evaluated to investigate their surface activity, aggregation particle sizes, and surface charges. The demulsification performances of the prepared Arabic heavy crude oil seawater emulsions in the presence of different concentrations of IPy-IL and AIPy-IL were evaluated and proved by interfacial tension, particle size, and demulsification efficiencies at a temperature of 45 °C. The data concluded that AIPy-IL was an effective demulsifier for different crude oil seawater emulsion compositions at a low injection dose and temperature of 100 ppm and 45 °C, which were not report elsewhere.

Dual Stimuli-Responsive Pickering Emulsions from Novel Magnetic Hydroxyapatite Nanoparticles and Their Characterization Using a Microfluidic Platform

Stimuli-responsive emulsifiers have emerged as a class of smart agents that can permit regulated stabilization and destabilization of emulsions, which is essential for food, cosmetic, pharmaceutical, and petroleum industries. Here, we report the synthesis of novel "smart" hydroxyapatite (HaP) magnetic nanoparticles and their corresponding stimuli-responsive Pickering emulsions and explore their movement under confined spaces using a microfluidic platform. Pickering emulsions prepared with our magnetic stearic acid-functionalized Fe₂O₃@HaP nanoparticles exhibited pronounced pH-responsive behavior. We observed that the diameter of emulsion droplets decreases with an increase in pH. Swift demulsification was achieved by lowering the pH, whereas the reformation of emulsions was achieved by increasing the pH; this emulsification-demulsification cycling was successful for at least ten cycles. We used a microfluidic platform to test the stability of the emulsions under flowing conditions and their response to a magnetic field. We observed that the emulsion stability was diminished and droplet coalescence was enhanced by the application of the magnetic field. The smart nanoparticles we developed and their HaP-based emulsions present promising materials for pharmaceutical and petroleum industries, where responsive emulsions with controlled stabilities are required.

Encapsulation and sedimentation of nanomaterials through complex coacervation

HYPOTHESIS

Nanoparticles removal from seawage water is a health and environmental challenge, due to the increasing use of these materials of excellent colloidal stability. Herein we hypothesize to reach this objective through complex coacervation, a straightforward, low-cost process, normally accomplished with non-toxic and biodegradable macromolecules. Highly dense polymer-rich colloidal droplets (the coacervates) obtained from a reversible charge-driven phase separation, entrap suspended nanomaterials, allowing their settling and potential recovery.

EXPERIMENTS

In this work we apply this process to highly stable aqueous colloidal dispersions of different surface charge, size, type and state (solid or liquid). We systematically investigate the effects of the biopolymers excess and the nanomaterials concentration and charge on the encapsulation and sedimentation efficiency and rate. This strategy is also applied to real laboratory water-based wastes.

FINDINGS

Long-lasting colloidal suspensions are succesfully destabilized through coacervate formation, which ensures high nanomaterials encapsulation efficiencies (~85%), payloads and highly tranparent supernatants (%T ~90%), within two hours. Lower polymer excess induces faster clearance and less sediments, while preserving effective nanomaterials removal. Preliminary experiments also validate the method for the clearance of real water residuals, making complex coacervation a promising scalable, low-cost and ecofriendly alternative to concentrate, separate or recover suspended micro/nanomaterials from aqueous sludges.

Recent advances in applications of power ultrasound for petroleum industry

Power ultrasound, as an emerging green technology has received increasing attention of the petroleum industry. The physical and chemical effects of the periodic oscillation and implosion of acoustic cavitation bubbles can be employed to perform a variety of functions. Herein, the mechanisms and effects of acoustic cavitation are presented. In addition, the applications of power ultrasound in the petroleum industry are discussed in detail, including enhanced oil recovery, oil sand extraction, demulsification, viscosity reduction, oily wastewater treatment and oily sludge treatment. From the perspective of industrial background, key issue and resolution mechanism, current applications and future development of power ultrasound are discussed. In addition, the effects of acoustic parameters on treatment efficiency, such as frequency, acoustic intensity and treatment time are analyzed. Finally, the challenges and outlook for industrial application of power ultrasound are discussed.

Displacement of interfacially-bound monoglyceride crystals in water-in-oil emulsions by a non-ionic surfactant

HYPOTHESIS

Micron and nano-scale particles are increasingly used to stabilize water-in-oil (W/O) emulsions. Though remarkably stable, the resulting emulsions can be broken by adding low molecular weight surfactants that modify the wettability of the interfacially-adsorbed particles.

EXPERIMENTS

W/O emulsions were prepared using lipophilic crystals of the monoglyceride glycerol monostearate (GMS), followed by addition of sorbitan monooleate (SMO) at concentrations below and above its critical micelle concentration (CMC). Systematic measurements of interfacial tension and three-phase contact angles, as well as characterization of emulsion sedimentation and microstructure, were used to assess GMS crystal wettability and emulsion destabilization.

FINDINGS

GMS crystals formed shells around the dispersed droplets, resulting in emulsions stable against breakdown under quiescent conditions. With SMO concentrations added below CMC, emulsion stability was not significantly affected. At SMO concentrations above CMC, the integrity of the crystalline shell was markedly affected. Notably, the GMS crystals transitioned from preferential oil-wet to water-wet behavior, eventually leading to their diffusion into the droplets. Therefore, in-situ modification of particle wettability at the oil-water interface was responsible for emulsion breakdown. Findings from this study may provide a pathway for the design of particle-stabilized W/O emulsions with controllable breakdown properties for applications such as tailored release of aqueous bioactive compounds.

Optimization of acoustic parameters for ultrasonic separation of emulsions with different physical properties

Ultrasound is an emerging and promising method for demulsification, which is highly affected by acoustic parameters and emulsion properties. Herein, a series of microscopic and dehydration experiments are carried out to investigate the parameter optimization of ultrasonic separation. The results show that the optimal acoustic parameters highly depend on the emulsion properties. For low frequency ultrasonic standing waves (USWs), mechanical vibrations not only facilitate droplet collision and coalescence, but also disperse the surfactant absorbed on the interface to decrease the interfacial strength. Therefore, low frequency ultrasound is suitable for separating emulsions with high viscosity and high interfacial strength. Increasing the energy density to produce moderate cavitation can increase demulsification efficiency. However, excessive cavitation results in secondary emulsification. In high frequency USWs, the droplets migrate directionally and form bandings, thereby promoting droplet coalescence. Therefore, high frequency ultrasound is favorable for separating emulsions with low dispersed phase content and small droplet size. Increasing the energy density can accelerate the aggregation of droplets, however, excessive energy density causes acoustic streaming that disturbs the aggregated droplets, resulting in reduced demulsification efficiency. This work presents rules for acoustic parameter optimization, further advancing industrial applications of ultrasonic separation.

Stability, deformation and rupture of Janus oligomer enabled self-emulsifying water-in-oil microemulsion droplets

Microemulsions exist widely in nature, daily life and industrial manufacturing processes, including petroleum production, food processing, drug delivery, new material fabrication, sewage treatment, etc. The mechanical properties of microemulsion droplets and a correlation to their molecular structures are of vital importance to those applications. Despite studies on their physicochemical determinants, there are lots of challenges of exploring the mechanical properties of microemulsions by experimental studies. Herein, atomistic modelling was utilized to study the stability, deformation, and rupture of Janus oligomer enabled water-in-oil microemulsion droplets, aiming at revealing their intrinsic relationship with Janus oligomer based surfactants and oil structures. The self-emulsifying process from a water, oil and surfactant mixture to a single microemulsion droplet was modulated by the amphiphilicity and structure of the surfactants. Four microemulsion systems with an interfacial thickness in the range of 7.4-17.3 Å were self-assembled to explore the effect of the surfactant on the droplet morphology. By applying counter forces on the water core and the surfactant shell, the mechanical stability of the microemulsion droplets was probed at different ambient temperatures. A strengthening response and a softening regime before and after a temperature-dependent peak force were identified followed by the final rupture. This work demonstrates a practical strategy to precisely tune the mechanical properties of a single microemulsion droplet, which can be applied in the formation, de-emulsification, and design of microemulsions in oil recovery and production, drug delivery and many other applications.