Demulsifier Research Articles

Research and Application Progress of Crude Oil Demulsification Technology

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.

Preparation and performance evaluation of a low‐damage fracturing fluid for unconventional reservoirs

AbstractThe characteristics of tight matrix, underdeveloped natural fractures, small pore throat radius, poor pore connectivity, and abundant clay minerals result in a high potential for damage to the tight sandstone reservoirs of the Shaximiao Formation in the Qiulin Block in the Sichuan Basin. In order to reduce the retention damage caused by fracturing fluid to the tight sandstone reservoir, a low damage fracturing fluid system applicable to the target reservoir is developed in this work, and the indoor performance meets the requirements of on‐site fracturing operation. A low‐damage, heat‐resistant, shear‐stable amphiphilic polyacrylamide (PAAD) was prepared by free radical polymerization in aqueous solution using acrylamide, acrylic acid, and methacryloyloyloxyethyl dimethyloctadecyl ammonium bromide (DM18) as the monomers. The amphoteric polyacrylamide was characterized by Fourier infrared spectroscopy, nuclear magnetic resonance spectroscopy (1H NMR), light scattering molecular weight determination, and thermogravimetric analysis. Fracturing fluids were formulated with the amphiphilic hydrophobic associative polymer PAAD as a drag‐reducing agent, the fluorine‐containing and nonionic complex surfactant FD1 as a clean‐up additive, CT10‐4B as a bactericide and CT1‐12 as an emulsion breaker. The fracturing fluid formulation was preferred, and the performance of the fracturing fluid was evaluated in terms of temperature resistance and shear resistance, drag reduction, anti‐expansion, and core damage. The fracturing fluid showed good temperature and shear resistance, with a viscosity retention of 58.4% at 120°C and 170 s−1 shear for 1 h. At a loading of 0.1%, the drag reduction rate reaches 72.3%, the anti‐expansion rate of the gel‐breaking fluid is 86.04%, and the damage rate to the tight sandstone core is 16.25%. The results show that the fracturing fluid has good heat resistance and shear stability, as well as low damage and good resistance reduction and anti‐expansion properties. This work can provide new strategies for designing polymeric fracturing fluids with low damage, good heat resistance and shear stability.

Adsorption behavior of non-ionic demulsifiers at the oil/water interface stabilized by asphaltenes: Experiments, adsorption kinetics, and mechanisms

Formation of emulsions containing asphaltenes is both undesirable and unavoidable in petroleum production. Chemical demulsifiers, such as non-ionic surfactants, have long been applied as the cheapest and most effective method of breaking emulsions by altering the oil/water interfacial properties. In this study, the association state of the asphaltenes, the dehydration rate, and the interfacial rheology under various demulsifier concentrations were used to analyze the contributions of non-ionic demulsifiers to the breaking of the asphaltene-containing emulsions. Additionally, the dynamic interfacial tension (DIFT) data over time were used to investigate the adsorption kinetics of the asphaltenes and the demulsifier at the oil/water interface. Results indicate that liquid paraffin enhanced the association of the asphaltene molecules, while the non-ionic demulsifier rendered asphaltene aggregate sizes smaller. The addition of the demulsifiers reduced the interfacial strength, leading to an unstable interface. The oil-soluble demulsifiers reduced IFT more effectively than the water-soluble ones, due to their faster migration rate and low interfacial tension gradient to the oil–water interface. The adsorption process of the asphaltenes, influenced by the demulsifier concentration, could be divided into three stages: a short-term diffusion-controlled process, a transition process, and a slow descent process (referred to as Regimes I, II, and III). In Regime I, the diffusion coefficient of asphaltenes increased with the demulsifier concentration, indicating that the demulsifier aided the dispersing of the asphaltenes in the solution. The equilibrium IFT and the maximum surface excess concentration of the asphaltenes in the long-term adsorption process decreased with the demulsifier concentration, indicating that the asphaltene-containing emulsions generally became unstable after adding the demulsifiers. Our results offer valuable insights into the adsorption kinetics and the mechanisms of alterations by the asphaltenes and demulsifiers of the oil/water interface, with implications for various interfacial phenomena (e.g., emulsion stability) involving surfactants in oil production, transportation, and processing.

Probing the interactions between asphaltenes and a PEO-PPO demulsifier at oil–water interface: Effect of temperature

HypothesisAsphaltenes are primary stabilizers in water-in-oil (W/O) emulsions that cause corrosion and fouling issues. In oil sands industry, oil/water separation processes are generally conducted at high temperatures. A high temperature is expected to impact the interactions between asphaltenes and emulsion breakers (EBs), consequently influencing demulsification performance. ExperimentsThe adsorption and interactions of asphaltenes and a PEO-PPO type EB (Pluronic F68) at the oil–water interface were investigated at various temperatures, using tensiometer, quartz crystal microbalance with energy dissipation (QCM-D), and atomic force microscopy (AFM). The effect of temperature on EB’s demulsification performance was explored through bottle tests. Additionally, demulsification mechanisms were studied using direct force measurements with the droplet probe AFM technique. FindingsDynamic interfacial tension and QCM-D results demonstrate that the PEO-PPO type EB exhibits higher interfacial activity than asphaltenes and can disrupt rigid asphaltene films at the oil–water interfaces. Elevated temperatures accelerate the displacement of adsorbed asphaltenes by EB molecules, leading to sparse interfacial films, rapid droplet coalescence, and improved demulsification efficiency (supported by AFM and bottle test results). This work provides valuable insights into interfacial interactions between asphaltenes and EB at different temperatures, enhancing the understanding of demulsification mechanisms and offering useful implications for the development of efficient EBs to enhance oil/water separation performance.

A CO2-responsive Janus SiO2 nanofluid: Integration of enhanced oil recovery and demulsification

Aiming to address the issues of limited suitability of conventional chemical oil displacement materials for formation conditions and the serious emulsification of oil and water in the produced liquid, the innovative nano oil-displacing system with CO2-responsive behavior has been developed. This system integrates oil displacement and emulsion breaking. The efficacy of the CO2-response system in creating stable emulsions with a high capacity to decrease interfacial tension has been demonstrated. The interfacial responsive behavior of all active components, including Janus nanoparticles, sodium oleate, gums, and asphaltenes, in the emulsion system was analyzed in terms of interfacial rheology and adsorption. Additionally, the prepared system demonstrated a rapid response to CO2, effectively breaking the emulsion within 5 min. Furthermore, the oil recovery enhancing mechanism of the CO2-response system was investigated using a microscopic visualization model. The system was proved to be efficient in initiating the residual oil within pore channels. Considering the combined effectiveness of the CO2-response system in terms of efficient oil displacement and rapid response, it offers valuable insights for advancing the chemical flooding technology of in enhanced oil recovery.

Study on Demulsification Pre-Treatment of Emulsified Wastewater

In this paper, the flocculation effect of single flocculants and compound flocculants on emulsified wastewater under different conditions was studied. The effect of flocculant type, dose, settling time and composite ratio of flocculant on the treatment of emulsified wastewater were investigated through single-factor condition tests, and then the optimal conditions of flocculants for treating emulsified wastewater were obtained. The results showed that the single inorganic flocculant could break the stable state of the emulsion when the pH was adjusted to 7 and formed tiny flocs, but it took a long time to settle down. The single organic flocculant had no flocculation effect. The inorganic–organic composite flocculants could effectively solve the problem of emulsion breaking and flocculation, and could form large flocs and alum flower formations at the same time, with mud and water effectively separated. The best conditions for the composite flocculants were as follows: under the condition of room temperature and pH 7, the dose of PFC was 2250 mg/L and APAM was 5 mg, the homogeneous stirring time was 10 min, and the settling time was 0.5 h. The removal rate of COD and turbidity reached 84.75% and 99.86%. The study could provide a new treatment idea and method for the pretreatment of stabilized high-turbidity wastewater.

Demulsification of steam-assisted gravity drainage (SAGD) emulsions under high temperature and high pressure: Effects of emulsion breaker and reverse emulsion breaker dosages

Effective treatment of complex emulsions formed during steam-assisted gravity drainage (SAGD) production is crucial for oil/water separation and subsequent processing. However, it remains challenging due to the complexity of SAGD emulsions, and there are only very limited studies on demulsification under simulated SAGD conditions. This study systematically characterized the comprehensive properties of a fresh field SAGD emulsion with about 84.6 % water and 15.4 % bitumen, and then achieved effective demulsification under a simulated SAGD condition at 135 °C and 60 psi via adding a poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) copolymer (as a model emulsion breaker or EB) combined with a branched polyethylenimine (PEI, as a model reverse emulsion breaker or REB) in a bench-scale bottle test setup. The effects of EB and REB dosages on the demulsification of the SAGD emulsion were evaluated based on the properties of the separated phases. Dynamic interfacial tension, zeta potential, and coalescence time were measured to reveal the demulsification mechanisms of EB and REB. The highly interface-active EB facilitated oil dehydration by displacing the natural interface-active species at the interfaces, disrupting the rigid interfacial films and promoting water droplet coalescence, while the cationic REB aided water de-oiling by neutralizing oil droplet surface charges, disrupting the rigid interfacial films and promoting the approach and coalescence of oil droplets in aqueous media. This work has improved the understanding of SAGD emulsion characteristics, the effects of EB and REB dosages on the demulsification performance, and the underlying demulsification mechanisms in SAGD operations. The results provide useful insights for developing effective and cost-efficient chemical approaches to address challenging emulsion issues in oil production.

A new method based on extraction induced by emulsion breaking for determination of Co and Ni in chocolate bars by graphite furnace atomic absorption spectrometry

This paper describes a new experimental configuration of extraction induced by emulsion breaking method to extract and determine Ni and Co in chocolate bars by graphite furnace atomic absorption spectrometry. At optimized conditions, the sample (0.08 g) was mixed with 4 mL of extractant solution (4% m/v Triton X-100 and 10% v/v HNO3) in a plastic syringe to form a solid-oil-water emulsion. Then, emulsion breaking was assisted by membrane filtration. The total extraction procedure took approximately 1 min, in opposition to 25 (centrifugation) and 50 min (heating). Extraction yields ranged from 94.8 to 114.3% for Co and from 85.9 to 108.4% for Ni. The limits of detection and quantification were, respectively, 24.73 and 82.45 μg Kg−1 for Co and 49.05 and 163.5 μg Kg−1 for Ni. Recoveries ranged from 92.1 (Ni) to 105.4% (Co).

Ionic liquid assisted extraction induced by emulsion breaking for extraction of trace metals in diesel, gasoline and kerosene prior to ICP-OES analysis

This study describes a novel and greener ionic liquid assisted extraction induced by emulsion breaking (ILA-EIEB) method for extraction of As, Ba, Cd, Cr, Ni Pb, Sb, Sn, Tb, Te and V in fuel oils. The most influential extraction parameters were ionic liquid concentration [(1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)], HNO3 concentration, Triton X-100 concentration, and sample mass and were optimised by using full factorial and Box-Behnken designs. The optimum conditions obtained were 0.035 % 1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) concentration, 18 % v/v HNO3 concentration, 15 % w/v Triton X-100 concentration, and 0.1 g sample mass. The emulsions were fully broken by using a controlled heating water bath at temperature of 80 ± 2 °C for 30 ± 4 min, followed by centrifugation at 3500 rpm for 15 min. Under the optimum conditions, the proposed ILA-EIEB method was accurate (80.1–101 %) and precise (1.9–4.7 %) for all the investigated metals. The method detection limits were 0.107, 0.013, 3.494 and 0.560 μg/g for Ba, Na, Ni and V, respectively. The optimised ILA-EIEB method was then applied in real fuel samples and metal concentration levels ranged from 0.072 to 8.610 μg/g, which were consistent with other literature reported work. Therefore, this study suggests that the examined metal ions present in fuel oils commercialised in Johannesburg, South Africa are in tolerable concentration levels and are not a threat.

Functionality of chemical additives and experimental conditions during formation of acid-induced emulsion and sludge

Petroleum has still maintained its position among energy sources, and there is a considerable demand for its higher production. A viable process that could improve oil production is acid stimulation. In this process though, acid-induced emulsion and sludge formation may profoundly compromise its performance. This study concentrates on experimental evaluation of these drawbacks considering the influence of several chemical additives that are usually used in acid stimulation including corrosion inhibitor, corrosion inhibitor intensifier, suspending, and iron control agents. In addition, the effect of operating conditions such as the volumetric ratio of acid and crude oil, mixing shear, ferric ions concentration, and various acid systems were studied during emulsion phase separation and sludge formation. Acid systems including HCl 15 and 28 wt% solutions, spent HCl, hybrid (a mixture of HCl and acetic acid), and emulsified acids (HCl in diesel) were also investigated. The results confirmed that although the additives are necessary for their main functionalities, nonetheless, they postponed the emulsion phase separation for at least 30 min. They also showed only meagre impact on the amount of formed sludge (<1 %), and a meaningful relationship could not be established between their presence and sludge formation. The acid phase volumetric ratio had an inverse impact on emulsion stability in such a way that 10 times more emulsion break happened by increasing the volumetric ratio from 0.25 to 0.75. Unlike previous studies, ferric ions formed less stable emulsions due to the presence of corrosion inhibitor and iron control agents. However, they were not able to control sludge formation. In addition, hybrid and emulsified acids showed high acid-crude oil emulsion stability for all samples along with higher amounts of sludge. Finally, spent acid showed less affinity to form sludge and emulsion.

Measurement of the Promoting Effect of Complex Conditions on the Adhesion Development in Curing Process of Cold Recycling Mixture with Emulsified Asphalt

The curing process of cold recycling mixture with emulsified asphalt is a process of emulsion breaking, water evaporation, and cement hydration, resulting in adhesion development and strength formation. There are many factors that affect this process, including curing temperature, curing time, reclaimed asphalt pavement (RAP) contents, and cement contents. However, the evaluation of the promoting effect of each factor is still not quite clear. Hence, in this paper, the curing temperature, curing time, and RAP contents were discussed to find out the dominating factor in this process. The development of moisture loss and indirect tensile strength (ITS) was measured and analyzed through establishing prediction models between them and curing time. Besides, the functional relationship between moisture loss and ITS was also analyzed to evaluate the promoting effect of each factor. The results showed that the curing temperature has a certain impact on the development of moisture loss and ITS and an increase in curing temperature would accelerate the reaction rate, while RAP contents can hardly affect this process. Through functional relationship between moisture loss and ITS, it was found that the development of early strength and adhesion was dominated by ITS despite the increase of curing temperature and RAP contents. Expanding the hydration effect of cement could promote the curing process. However, this dominating role weakened at higher temperature and moisture loss should be treated more carefully.

DETERMINAÇÃO MULTIELEMENTAR EM AMOSTRAS DE BIODIESEL EMPREGANDO ESPECTROMETRIA DE FLUORESCÊNCIA DE RAIOS-X POR DISPERSÃO DE ENERGIA APÓS EXTRAÇÃO INDUZIDA POR QUEBRA DE EMULSÃO

MULTI-ELEMENT DETERMINATION IN BIODIESEL SAMPLES USING ENERGY DISPERSIVE X-RAY FLUORESCENCE SPECTROMETRY AFTER EXTRACTION INDUCED BY EMULSION BREAKING. A method for determining Cd, Cr, Cu, and Fe in biodiesel samples is proposed using energy dispersive X-ray fluorescence spectrometry (EDXRF) after extraction induced by emulsion breaking (EIEB). A volume of 7.0 mL of biodiesel and an aliquot of 500 µL of Triton X-100 solution (2%, v v-1) prepared in nitric acid were used to prepare the emulsion. After 5 min of manual agitation, phase separation was performed by centrifugation for 5 min at 2000 rpm. A 100 µL aliquot of the enriched aqueous phase was collected and applied to the center of a filter paper. After drying, the analysis was performed directly on the paper using EDXRF. The detection limits were 60, 20, 30, and 60 μg kg-1 for Cd, Cr, Cu, and Fe, respectively. Recovery tests were performed by adding 450 μg kg-1 of the analytes in biodiesel samples, and the results varied between 87 and 113%. The procedure was applied to biodiesel samples, and the concentrations obtained for the four analytes were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP OES) after sample digestion.

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

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

Synthesis and Application of a Novel Multi-Branched Block Polyether Low-Temperature Demulsifier.

In this paper, a low-temperature thick oil demulsifier with high polarity was prepared by introducing ethylene oxide, propylene oxide block, and butylene oxide using m-diphenol as a starting agent. The main reasons for the difficulty involved in the low-temperature emulsification of extractive fluids were explained by analyzing the synthetic influencing factors and infrared spectra of the star comb polymer (PR-D2) and by analyzing the four fractions, interfacial energies, and zeta potentials of crude oils from the Chun and Gao fields. The effects of PR-D2 surfactant on the emulsification performance of crude oil recovery fluids were investigated via indoor and field experiments. The experimental results indicate that the optimal synthesis conditions for this emulsion breaker are as follows: a quality ratio of ionic reaction intermediates and meso-diphenol of R = 10:1; 1 g of the initiator; a polymerization temperature of 80 °C; and a reaction time of 8 h. Colloidal asphaltenes in the crude oil were the main factor hindering the low-temperature demulsification of the Gao oilfield's extractive fluids, and the reason for the demulsification difficulty of the extractive fluids in the Chun oilfield is that the temperature of demulsification is lower than the wax precipitation point. The demulsification rate of the Chun oilfield's extractive fluids reached more than 98% when the PR-D2 concentration reached 150 mg/L at 43 °C. The demulsification rate of the Gao oilfield's extractive fluids reached more than 98% at a PR-D2 concentration of 150 mg/L at 65 °C. The field experiments show that the Chun oilfield's extractive fluids can still demulsify after the temperature is reduced to 43 °C in winter. The emulsification temperature of the Gao oilfield's extractive fluids was reduced from 73 °C to 68 °C, with an excellent demulsification effect.

Intelligent control of emulsion stability and evaluation of selective water shutoff performance

Using hydrophobic nano-SiO2 and a tiny amount of non-ionic and anionic surfactants as stabilizers, a Pickering emulsion system for oil-in-water in high-temperature and high-mineralization reservoirs was developed. At high temperatures (120 °C) and high mineralization (37000 mg/L), the emulsion system shows outstanding stability. The addition of the auxiliary agent can effectively control the time of emulsion breaking and nanoparticle release. The auxiliary agent will "compete" with the surfactant for adsorption on nanoparticles at the oil/water interface, weakening the surfactant's anchoring effect and causing a decrease in the surface roughness of the nanoparticles, resulting in a decrease in the mechanical strength of the interfacial film. Furthermore, the presence of H+ in the solution neutralizes part of the negative charges on the surface of emulsion droplets, which is detrimental to emulsion stability because electrostatic repulsion between droplets is diminished. The released SiO2 particles agglomerate in the pore throat to form a hydrophobic filter cake, which can be used to achieve intelligent water control in high-temperature and high-mineralization reservoirs (1000 mD), with an aqueous phase plugging rate of 95.83% and an oil phase plugging rate of 25.32%.

Rapid preparation of Ni/Fe-LDH@ stainless steel mesh with interfacial emulsion breaking effect for efficient oil-in-water emulsion separation

Oil-water separation materials are particularly important for today's polluted water, especially the easy preparation of separation materials and the efficient separation of emulsions. The excellent properties of layered double hydroxide (LDH) have led to its successful application in the field of oil-water separation, but most of the existing studies have used high-temperature and long-time hydrothermal methods for the growth of LDH. Here, we present a stainless-steel mesh material for the preparation of LDH by electrochemical methods, which can be prepared in a few minutes, greatly improving the production efficiency. Adjusting the electrodeposition time of LDH can well regulate the aperture of the stainless-steel mesh to realize the sieving of emulsion droplets, in addition, the positive charge of LDH is helpful to promote the rupture of emulsion droplets and improve the emulsion separation efficiency. The separation efficiency of this rapidly prepared separation material for oil-in-water emulsions was stabilized at more than 99.3%. In addition, the preparation with low energy consumption is more in line with the concept of green development and more conducive to practical applications.

Pickering Emulsions and Viscoelastic Solutions Constructed by a Rosin-Based CO2-Responsive Surfactant.

Designing stimulus-switch viscoelastic solutions and Pickering emulsions with reversible CO2-responsive behavior remains a challenge. A rosin-based CO2-responsive surfactant, N-cetyl-maleimidepimaric acid N,N-dimethylenediamide (C16MPAN), was synthesized and used to prepare CO2-triggered viscoelastic solutions and Pickering emulsions. This surfactant exhibited excellent CO2-responsive performance in water and formed a viscoelastic solution. This viscoelastic system was investigated by dynamic light scattering (DLS), rheology, and cryogenic transmission electron microscopy (Cory-TEM). The shear viscosity of the system increased by 3-4 orders of magnitude after bubbling with CO2 and a large number of elongated, flexible, tubular wormlike micelles were observed. Further, Pickering emulsions were prepared by C16MPAN+ synergistically with cellulose nanocrystals (CNCs), whose stability and switchability were investigated via adsorption isotherm, droplet size, contact angle, and macroscopic photographs. C16MPAN+ was adsorbed with CNCs to form mechanical barriers at the oil-water interface, making the emulsion stable for at least three months, and desorption from CNCs enabled emulsion breaking. The cycle could be switched reversibly multiple times and the particle size distribution of emulsion was basically the same. This work enriches the application of biomass resources in intelligent responsive materials.

Determination of Cr and Pb in edible vegetable oils by coupling of extraction induced by emulsion breaking with dispersive liquid-liquid microextraction followed by flame atomic absorption spectrometry detection

This study presents an efficient method for the determination of chromium and lead in various edible vegetable oils by combination of extraction induced by emulsion breaking (EIEB) and dispersive liquid-liquid microextraction (DLLME) followed by flame atomic absorption spectrometry (FAAS) detection. The technique relies on the formation of a water-in-oil emulsion, achieved by introducing an extraction phase containing 20% (w/v) Triton X-100 and 1% (v/v) nitric acid. The metal ions were extracted to the aqueous phase through centrifugation of the resulting emulsion. Subsequently, the collected aqueous phase was mixed with dithizone, and the pH of solution was adjusted at 8 and 9 for Cr and Pb, respectively. Finally, DLLME was applied to concentrate the extracted metal ions, which were then quantified using FAAS. Various factors affecting the extraction efficiency of selected the metal ions were optimized using one-variable-at-a-time method. The estimated limit of quantifications were 5.0 µg/kg and 2.0 µg/kg for lead and chromium, respectively. The standard addition method was used to construct the calibration curves. The calculated relative recoveries for the spiked oil samples ranged from 94.0% to 98.0% for chromium, and from 92.0% to 96.4% for lead. The results showed that the proposed technique offers a simple and efficient analytical methods for the determination of lead and chromium in oil samples.

Synthesis and Performance Study of pH/Magnetic Dual Response Chitosan Based Emulsifiers

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.

Microwave-assisted extraction based on emulsion breaking with natural deep eutectic solvent for vegetable oil sample preparation prior to elemental determination by ICP OES

This study presents a novel and efficient method for the extraction of Al, Ca, Cr, Cu, K, Mg, Mn, and Zn in vegetable oil samples using a Natural Deep Eutectic Solvent (NADES) as an extractor combined with microwave radiation (MW) in an emulsion system. The NADES prepared with choline chloride:oxalic acid:water (1:1:4 molar ratio) provided a high extraction rate using 5.0 mL of the sample, 1.7 mL of NADES, and 1.3 mL of Triton X-100. The optimum conditions were obtained with 36 s of vortexing, 5 min of extraction, and 10 s for emulsion-breaking in MW. Under these conditions, recoveries ranged from 91% to 110% and relative standard deviations <9.0% were obtained. The limit of quantification (mg kg−1) was: 0.018 (Al), 0.032 (Ca), 0.007 (Cr), 0.006 (Cu), 0.013 (K), 0.027 (Mg), 0.002 (Mn), and 0.019 (Zn). The proposed method showed comparable results to reference methods and advantages, such as speed, low cost, and simplicity. The combination of NADES and MW represents a sustainable and innovative approach to the elemental determination composition of vegetable oils and contributes to advances in sample preparation methods.