Separate Oil Phase Research Articles

Variations in Oil Occurrence State and Properties during High-Speed Stirring Treatment of Oily Sludge.

Oily sludge (OS) has long been regarded as a hazardous waste, and improper disposal may lead to serious environmental concerns and human health risks. Despite various methods having been proposed and applied to the treatment of OS, the oil occurrence states and properties in sludge are rarely characterized, which may directly link to the selection and effectiveness of treatment methods. Here, confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), gas chromatography (GC), and four components (SARA) analysis were utilized to characterize the changes in the oil occurrence states and compositions in OS samples before and after high-speed stirring (HSS) treatment. Our results show a substantial reduction in the oil concentration of OS after HSS treatment (from 32.98% to 1.65%), while SARA analysis reveals a similar oil composition before and after treatment, suggesting the broad applicability of HSS in removing oil and its insignificant selectivity towards various hydrocarbon components. This is further supported by the total petroleum hydrocarbon (TPH) analysis results, which show that the separated oil phase has a hydrocarbon composition similar to that of the original OS sample. The CLSM and fluorescence analysis suggest a homogeneous distribution of oil in the sludge, with relatively light components more concentrated in the pore systems between coarse mineral particles, whereas relatively heavy components tend to coexist with clay minerals. After HSS cleaning, both light and heavy components are removed to varying degrees, but light components are preferentially removed while heavy components tend to be retained in the sludge due to adsorption by clay minerals. This is consistent with TPH analysis, where a significant decrease in n-alkanes with lower carbon numbers (n-C14 to n-C20) was observed in the residual sample. Our findings demonstrate the dynamic response of oil occurrence states and compositions to the OS treatment process and highlight the importance of characterizing these fundamental properties prior to the selection of OS treatment methods.

Evaluating the Stability and Digestibility of Long-Chain Omega-3 Algal Oil Nanoemulsions Prepared with Lecithin and Tween 40 Emulsifiers Using an In Vitro Digestion Model.

The health benefits of long-chain omega-3 polyunsaturated fatty acid (LCn-3PUFA) intake have been well documented. However, currently, the consumption of oily fish (the richest dietary source of LCn-3PUFA) in the UK is far below the recommended level, and the low digestibility of LCn-3PUFA bulk oil-based supplements from triglyceride-based sources significantly impacts their bioavailability. LCn-3PUFA-rich microalgal oil offers a potential alternative for populations who do not consume oily fish, and nanoemulsions have the potential to increase LCn-3PUFA digestibility and bioavailability. The aims of this study were to produce stable algal oil-in-water nanoemulsions with ultrasonic technology to increase DHA digestibility, measured using an in vitro digestion model. A nanoemulsion of LCn-3PUFA algal oil was developed with 6% w/w emulsifiers: lecithin (LE) or an equal ratio of Tween 40 (3%) and lecithin (LTN) (3%), 50% w/w, algal oil and 44% w/w water using rotor-stator and ultrasound homogenization. The in vitro digestion experiments were conducted with a gastric and duodenal digestion model. The results showed the creation of nanoemulsions of LCn-3PUFA algal oils offers potentially significant increases in the bioavailability of DHA in the human body. The increase in digestibility can be attributed to the smaller particle size of the nanoemulsions, which allows for higher absorption in the digestive system. This showed that the creation of nanoemulsions of LCn-3PUFA algal oils offers a potentially significant increase in the bioavailability of DHA in the human body. The LE and LTN nanoemulsions had average droplet sizes of 0.340 ± 0.00 µm and 0.267 ± 0.00 µm, respectively, but the algal oil mix (sample created with same the components as the LTN nanoemulsion, hand mixed, not processed by rotor-stator and ultrasound homogenization) had an average droplet size of 73.6 ± 6.98 µm. The LTN algal oil nanoemulsion was stable in the gastric and duodenal phases without detectable destabilization; however, the LE nanoemulsion showed signs of oil phase separation in the gastric phase. Under the same conditions, the amount of DHA digested from the LTN nanoemulsion was 47.34 ± 3.14 mg/g, compared to 16.53 ± 0.45 mg/g from the algal oil mix, showing DHA digestibility from the LTN nanoemulsion was 2.86 times higher. The findings of this study contribute to the insight of in vitro DHA digestion under different conditions. The stability of the LTN nanoemulsion throughout digestion suggests it could be a promising delivery system for LCn-3PUFAs, such as DHA, in various food and pharmaceutical applications.

Stability and characteristics of kerosene-in-water emulsions with xanthate surfactants: Influence of hydrophilic-lipophilic balance and molecular weight

The understanding of emulsion stability is important for several industrial applications including foods, pharmaceuticals, petroleum, personal care products, and in our case mineral processing. Xanthate functional surfactants may be useful to improve mineral recovery through froth flotation by delivering oil to valuable mineral surfaces as they may be used to stabilize kerosene-in-water emulsions. The eco-friendly nature of naturally derived reagents such as vitamin E-based xanthates would be beneficial to the mineral processing industry. In this study, conventional (potassium amyl xanthate (PAX)) and novel xanthate functional surfactants such as α-tocopherol polyethylene glycol 400 succinate (TPGS) xanthates which we synthesized from Vitamin E were investigated as emulsifiers. The creaming and oil phase separation of the kerosene-in-water emulsions produced with the xanthate surfactants were studied. The influence of hydrophilic-lipophilic balances (HLBs) and molecular weights (MWs) of the water-soluble xanthates and other commercial surfactants including polyoxyethylene fatty acid esters (Tweens), sorbitan fatty acid esters (Spans), and polyoxyethylene fatty ethers (Brijs) on the characteristics of the kerosene-in-water emulsions was examined. The experimental results showed that the TPGS xanthate formed the most stable emulsion among the xanthate surfactants considered. The results indicated that HLB is not the only factor influencing the emulsifying properties of surfactants. The chemical structure, particularly the molecular weight of the surfactant has a significant impact on its emulsifying properties. Thus, an emulsion stability chart incorporating the HLB and molecular weight of surfactants is proposed. This stability chart can be used for a better classification of the emulsifying properties of commercially available surfactants and novel reagents.

Energy recoveries and heavy metal migration behaviors of different oily sludges treated by pyrolysis versus solvent extraction

The pyrolysis and trace element mitigation characteristics are investigated by contrast to solvent extraction for four oily sludges, including storage tank bottom sediment (OS-1), scum from a wastewater separator (OS-2), white-clay-adsorbed waste oil (OS-3), and settlings from wastewater treatment (OS-4). Slow pyrolysis at 700 °C generated a single oil phase for OS-1 and separate oil and aqueous phases for OS-2, OS-3 and OS-4. Up to 73.0–88.3 % of the total energy were recovered from OS-1, OS-2 and OS-3 in the oil phase with 19.9–77.1 % oil yield; however, the oil phase from OS-4 accounted for only 13.3 % of the total energy, while the aqueous product accounted for 68.0 % of the total energy. Quantification of 16 trace elements revealed that OS-2 and OS-4 had much higher contents of Cu/Zn/As/Se/Cd/Pb and Ni/Cu/Zn/Se/Cd contents than the average crustal abundances, respectively. Correlations between evaporation and extraction rates indicated that the mitigation behaviors of trace elements were related to their occurrence modes in different oily sludges. Except for Cd, As and Se, all other trace elements were enriched in the pyrolysis residues of the oily sludges. Ni in the pyrolysis residue of OS-4 posed a moderate potential ecological risk.

Ultrafine Starch Particles as Pickering Emulsion Stabilizers With Different Interfacial Behaviors

AbstractNative starch Pickering stabilizer without chemical modification has attracted research interest in food field. However, the behaviors of starch particles at interface are seldom studied. In this paper, ultrafine starch particles (USPs) are grounded with a planetary ball mall from various starch species down to 1–2 µm in size. USP and starches are used to prepare Pickering emulsions. With size decrease, USP has more negative zeta potentials, stronger hydrogen bonds, better hydrophilicity, and better emulsifying abilities than their counterparts of starches. Millet starch has better emulsion stability than OSA modified starch. Glutinous USP outperforms in stabilization due to higher emulsion height and no oil phase separation. USP behaves differently at interface or in water phase, which is attributed to starch species, amylose and amylopectin contents, and gelatinization. This work can inspire the behavior investigation of starch particles in nano/micrometers at interface during storage.

Stability of n‐hexadecane phase change material emulsions using sugar‐based surfactants and the HLD platform

AbstractStoring thermal energy and using renewable energy are some of the most important challenges humanity faces today. Using phase change materials (PCM) is a suitable solution to prevent heat loss. PCM emulsions (PCMEs) have several advantages and are specifically applied in heat exchangers. Here, the formulation of these emulsions, the type of surfactants, and their composition based on freeze–thaw cycle stability are investigated. The Hydrophilic–Lipophilic‐Deviation (HLD) platform is used for this purpose. Considering the importance of stability during temperature changes in PCMEs, three types of surfactants that have different behaviors with respect to temperature are used: ethoxylates, ionics, and sugar‐based surfactants. By performing freeze–thaw cycles on emulsions made by individual surfactants, after 10 freeze–thaw cycles it was observed that the oil separation in each of the samples containing polysorbate80, AOT, lauryl‐myristyl‐alcohol‐polyethylene‐glycol‐ether, SDS, sorbitan‐monooleate, and decylglucoside occurred at the 2nd, 4th, 6th, 7th, 8th, and 10th‐cycle, respectively. Therefore, the sorbitan‐monooleate and decylglucoside had better freeze–thaw cycle stability compared to the others because of their non‐sensitivity to temperature. We also applied the emulsion cycle stability with two combinations of surfactants: (1) polysorbate80 and sorbitan‐monooleate, (2) decylglucoside and sorbitan‐monooleate. The former, despite the effect of temperature, showed no oil phase separation in the nine freeze–thaw cycles, but in the latter, the oil phase separation occurred in the 5th‐cycle. This study shows that synergism of surfactants is the most important factor in the stability of emulsions. To better explore these emulsion systems, the storage stability, freeze–thaw stability, droplet morphology, and viscosity tests were performed on different samples at various HLD values.

Switchable Pickering Emulsions Stabilized via Synergistic Nanoparticles-Superamphiphiles Effects and Rapid Response to CO2/N2.

A CO2/N2-responsive emulsion provides milder reaction conditions, nontoxicity, and economic feasibility compared to other switchable surfactants. In this study, CO2/N2-responsive pickering emulsions were fabricated by using a compounded dispersion containing SiO2 nanoparticles (NPs) and superamphiphiles as the emulsifying agents. The synergistic effects of the SiO2 NPs and superamphiphiles significantly stabilized the emulsion at all of the tested concentrations and prevented complete phase separation of oil and water. The electrostatic interaction between the SiO2 NPs and superamphiphiles was disrupted after bubbling with CO2 for 30 s, resulting in the breaking of the emulsion. However, the dispersion recovered its interfacial activity after the introduction of N2 and again emulsified the emulsion. This reversible switching behavior was validated through three consecutive cycles of bubbling CO2/N2. The protonation and deprotonation of the SiO2 NPs and superamphiphiles in response to CO2/N2 facilitated reversible assembly and disassembly, which enabled the switching of the emulsions between inactive and active forms. The novel highly stable Pickering emulsions demonstrated rapid demulsification and emulsification in response to CO2/N2 and are promising for a wide range of applications.

Development of a laboratory setup for destruction of oil-water emulsions

The work describes a laboratory setup developed by the authors for destruction of oil-water emulsions. The setup can be used in chemical analytical testing laboratories as new auxiliary equipment for preparing samples of crude oils, which are oil-water emulsions, for obtaining dehydrated oil. The setup includes two borosilicate glass units: heating unit and desiccating unit. The heating unit consists of a conical vessel equipped with a heating element for programmable heating and thermostating of the vessel. The desiccating unit consists of a vessel with a drain hole at the bottom, into which, if necessary, a water-absorbing reagent (calcium chloride) is placed for deeper dehydration of the separated oil phase. The units are connected to each other by a glass adapter, which is equipped with two PTFE or KhN-1 type taps, for collecting water and oil phases into different receiving bottles. Feasibility of using calcium chloride as a drying agent was confirmed by a series of experiments on a model oil sample, in which fractions that boiled away at temperatures below 300 °C were preliminary removed. The data obtained confirmed the absence of partial adsorption of resinous-asphaltene substances during the passage of the separated oil phase through the drying reagent layer. Metrological characteristics of determining separated water fraction were calculated to assess the effectiveness of the laboratory installation. The result of using the developed laboratory setup is the complete destruction of direct and reverse type water-oil emulsions of varying degrees of stability, which could not be demulsified by known laboratory methods. As a result, separated oil phases with a water content of below 1% were obtained, which allows carrying out laboratory studies of oils to determine their composition and properties both to characterize the oils themselves and to establish the reasons for stability of analyzed emulsions.

Phase separation dynamics in wetting ridges of polymer surfaces swollen with oils of different viscosities.

When drops are placed on a sufficiently soft surface, the drop surface tension drives an out of plane deformation around the contact line (i.e., a wetting ridge). For soft elastomeric surfaces that are swollen with a liquid, capillarity from a drop can induce a phase separation in the wetting ridge. Using confocal microscopy, we study the dynamics of phase separation at the wetting ridge of glycerol drops on silicone elastomers, which are swollen with silicone oils of varying viscosity (i.e., molecular weight). We show that the viscosity of the swelling oil plays a large role in the oil separation size and separation rate. For networks swollen to near their maximum swelling (i.e., saturated), lower viscosity oil separates more and separates faster at early times compared to larger viscosity oil. During late-stage wetting, the growth rate of the separation is a function of viscosity and swelling ratio, which can be described by a simple diffusive model and a defined wetting ridge geometry. In this late-stage wetting, the higher viscosity oil evidently grows faster, likely because it is further from reaching equilibrium. Interestingly, the separated oil phase region grows with a nearly constant, geometrically similar shape. Understanding how phase separation occurs on swollen substrates should provide information on how to control drop spreading, sliding, adhesion, or friction on such surfaces.

Effect of sesame protein/PVA nanofibers on oil separation and rheological properties in sesame paste

AbstractThis study aimed to prevent or minimize the oil phase separation that occurs during storage (0‐90 days) of sesame paste at room temperature. In order to determine the changes during storage in the sesame paste samples, the zeta potential, rheological properties, and the separated oil ratio were determined. Significant (p < 0.01) effects of applied storage time and additives on the amount of oil separated in sesame pastes were determined. The oil separated in sesame paste samples varied between 3.83% and 16.29%. While the rate of separated oil increased three times in the control group over time, it showed an insignificant (p > 0.05) increase especially in the samples where 2% nanofiber was added. It was determined that the separation of the oil phase from the structure could be prevented up to 24.73% with the addition of SPI and up to 63.02% with addition of SPINL (nanofiber containing protein isolate) compared to the control.Practical applicationsDuring storage, the particles in the sesame paste tend to precipitate, causing oil separation and residue cake, thus negatively affecting the acceptability of consumers. Additives were added in order to prevent or minimize oil phase separation, which occurs in sesame paste stored at room temperature and is not desired by consumers. As additives, nanofibers containing sesame proteins produced by the electrospinning method and sesame protein isolates (SPIs) were added. Added additives acted by preventing the separation of the oil phase from the structure. It has been determined that the addition of SPI to sesame pastes does not completely prevent the problem of oil separation in sesame paste, but is effective in delaying and reducing it. Since the oil decomposition can be reduced, the amount of oil separated and therefore the part that can sink to the bottom will decrease, so sesame paste will be consumed more appropriately and will contribute to the country's economy.

Synthesis and performance evaluation of water‐absorbing resin coated with polymethyl methacrylate as a lost circulation material

AbstractLost circulation will cause huge economic losses every year. In order to effectively reduce the harm of lost circulation to drilling, it is particularly important to use reasonable and efficient lost circulation materials (LCM). As a kind of water‐absorbing, expandable and deformable LCM, water‐absorbing resin can adapt to holes and cracks of different sizes. In this study, a kind of encapsulated water‐absorbing resin LCM (PMMA/PNAD) was proposed. The water‐absorbing resin is synthesized by acrylamide (AM), 2‐acrylamide‐2‐methyl‐propane sulfonic acid (APMS) and diallyl dimethyl ammonium chloride (DMDAAC) as reaction monomers through aqueous solution polymerization. The shell material is polymethylmethacrylate (PMMA), which is coated on the surface of the water‐absorbing resin by oil phase separation method. The results of the experimental evaluation indicate that the water‐absorbing resin possesses robust water‐absorbing and swelling properties, which significantly affect the rheological properties of the drilling fluid. However, the coated shell can effectively mitigate the impact of the absorbent resin on the drilling fluid. Under the formation environment of 100°C or 2 Mpa, the shell can soften or break to release the absorbent resin. The lost circulation control performance test results show that PMMA/PNAD has good pressure bearing capacity, and can still maintain good lost circulation control at 6.9 Mpa.

Cryogenic efficient phase separation of oil–water emulsions with amphiphilic hyperbranched poly(amido-amine)

Amphiphilic hyperbranched poly(amido-amine) with a core–shell structure based on multi-scale rational design as an efficient additive can enhance demulsification performance at low temperature.

Demulsification of phosphoric acid/ tri-n‑butyl phosphate (W/O) emulsion by a novel rotor-stator spinning disc device

The demulsification process of phosphoric acid/tri-n‑butyl phosphate (W/O) emulsion is investigated by a novel rotor-stator spinning disc device (RSSDD). Emulsion properties varied with emulsification rotor speed and phase ratio, and operating parameters such as flow rate and disc speed have been studied for their effects on demulsification efficiency D, relative volume of separated oil phase λ, dispersed phase fraction of creamed emulsion ɸc and change in the average droplet size of emulsion Δdc. The results show that D is primarily due to emulsion stability. Low emulsification rotor speed and phase ratio reduce the emulsion stability, resulting in an increase in D. The shear and centrifugal forces from rotation and the residence time, influenced by operating parameters, play a major role in D and Δdc. Operating at higher disc speed and lower flow rate is not supposed. D decreases with increasing flow rate and decreasing disc speed, while Δdc behaves in the opposite way. λ disperses within 1.52%-2.94%, resulting in a linear relationship between D and ɸc. The optimal operating parameters are determined with D of 41.12% for one cycle in RSSDD. A model is proposed for the prediction of D and ɸc, showing an acceptable agreement with the experimental results.

Geochemical behavior of aliphatic hydrocarbons during primary migration and implication for hydrocarbon expulsion: A case study in Qikou Sag, Bohai Bay Basin, eastern China

Lipid biomarker parameters and molecular carbon isotope compositions of n-alkanes were used as tracers to determine geochemical behavior of aliphatic hydrocarbons during their migration from two sequences of source rock-type mudstones (4050.8–4062.2 and 4067.4–4073 m depth, respectively) to the interbedded reservoir sandstones (4062.6–4066.3 m depth) in the Qikou Sag, Bohai Bay Basin, eastern China. Abnormally high values of the production index (0.69–0.90) and total extract/total organic carbon (TOC) ratios (0.53–1.21) in the sandstone samples indicated that the hydrocarbons in the sandstones were not produced in situ but migrated from the adjoining mudstones. A comparison of values in lipid biomarker parameters (oleanane index, gammacerane index, C23 tricyclic terpane/C30 αβ-hopane, and C29/C27 ααα20R sterane ratios) in the sandstone with the mudstone samples indicated steroids and hopanoids in the upper section of the sandstone layer (4062.6–4065.2 m depth) were transported from the overlying mudstones, while those in the lower sandstone layer (4066.3 m depth) were transported from the underlying mudstones. Molecular carbon isotope data suggest that all n-alkanes in the upper section of the sandstone layer were transported from the overlying mudstones. However, in the lower sandstone layer, most of the C15–C17n-alkanes were transported from the overlying mudstones, while the C18–C31n-alkanes were transported mainly from the underlying mudstones. These combined results suggest the short-chain n-alkanes (<C17) were expelled preferentially relative to other compounds (probably via molecule diffusion) while the long-chain n-alkanes (>C18) and steroids/hopanoids may have been expelled in a separate oil phase.

Crude oil emulsion breaking: An investigation about gravitational and rheological stability under demulsifiers action

Emulsions are common in the oil industry, being present in the extraction and production stages. Its formation occurs with the contact of brine and crude oil under intense flow. The presence of emulsified water (dispersed droplet size, φ ≤ 50 μm) in crude oil can negatively impact its exploration, transportation, and refining, making transportation more expensive, requiring more energy for heating, and causing equipment corrosion on all processes. In addition, crude oil has salts and sediments that encrust and corrode equipment of the primary oil treatment unit and distillation towers, also causing catalyst poisoning in the cracking step. Therefore, such components need to be removed for subsequent refining processes. To prevent these problems, the dehydration/desalting of crude oils is a strategy adopted to reach adequate values of water, salts, and sediments required in the refineries for the next steps after primary treatment. However, the emulsion breaking is influenced by several factors that affect the stability of crude oil (W/O emulsion), such as viscosity, contents of water, salts, sediments, and natural surfactants, among others. Given this perspective, this work investigated the stability of two different types of crude oils with demulsifier under the action of gravity (bottle test) and shear stress (rheology). The comparisons of gravitational and rheological techniques concluded that the shear stress sweep analyses are useful to evaluate the demulsifier performance in the emulsion breaking, being a reliable and fast methodology. Such studies allowed the identification of adequate parameters: temperature (80 °C) and, demulsifier type and quantity (500 ppm) for efficient crude oil phase separation, without using washing water. The physicochemical and rheological characterizations clarified the crude oil's colloidal stability behavior to understand the impurities' influence on the oils' properties (crude and desalted).

Investigation of Cement Prepared with Microencapsulated Microorganisms.

Cracks in underground rock masses cause gas leakage, seepage, and water inflow. To realize calcium carbonate deposition and mineralization filling in rock cracks, microencapsulated bacterial spores were prepared by an oil phase separation method. To optimize the microorganism growth conditions, the effects of microcapsules with various pHs, particle sizes, and amounts on microcrack self-healing were investigated through an orthogonal test, and the best conditions for repairing the cracks using microencapsulated Bacillus sphaericus were obtained. Infrared analysis and scanning electron microscopy were used to observe the morphological characteristics and coating performance of the microcapsules. The results showed that the microcapsules contained functional groups in the core and wall materials. The surfaces of the microcapsules prepared by the test were rough, which was beneficial for adhesion onto the fracture surface. X-ray diffraction analysis, X-ray photoelectron spectroscopy, and thermal analysis were conducted. The results showed that the microcapsules with pH = 8 and a particle size of 100 μm had the highest thermal decomposition temperature and the best thermal stability. The elements of the core and wall materials were detected in the microcapsules, and the coating had a beneficial effect. The compression and acoustic emission tests of the specimens embedding microbial capsules with different contents under different working conditions revealed that the two fractures of the specimen were due to the rupture of the microcapsule and the rupture of the rock specimen, indicating the best mechanical triggering properties and compressive properties of the microcapsule.

Research on the Preparation of Microbial Capsules by Epoxy Resin-Coated Bacillus pasteurii

With the increasing number of underground engineering construction projects such as coal mining, tunnel, and subway, water inrush disasters occur more and more frequently. Inspired by the phenomenon of microbial mineralization and diagenesis, microbial-induced calcium carbonate precipitation (MICP) is used to repair cracks in cement-based materials, which provides a new idea to solve the problem of water inrush. To investigate the self-healing properties of microbial capsules, this paper selected epoxy resin E-51 cured by DMP-30 as the wall material and Bacillus pasteurii as the core materials for experiments. In this paper, a single-factor method was adopted to determine the optimal preparation process of microbial capsules and the oil-phase separation method to prepare the microbial capsules. The effects of various factors on the experimental results under different core-wall ratios, reaction time, reaction temperatures, and agitation rates were analyzed. Microbial capsules were analyzed by Fourier transform infrared spectroscopy and optical microscopy to explore the functional groups and features of microbial capsules. The experimental results showed that the microbial capsules achieved the best performance with a core-to-wall ratio of 1 : 3, a reaction temperature of 50°C, a reaction time of 40 min, and a stirring rate of 300 rpm. Meanwhile, we determined the spore survival rate of microbial capsules and finally studied the waterproofness, storage stability, and rupture under the pressure of microbial capsules. We concluded that microbial capsules have high-efficiency and self-healing properties.

Water-in-Oil-in-Water Nanoemulsions Containing Temulawak (Curcuma xanthorriza Roxb) and Red Dragon Fruit (Hylocereus polyrhizus) Extracts.

Hydrophobic curcumin in temulawak extract and hydrophilic betacyanin in red dragon fruit extract are high-value bioactive compounds with extensive applications in functional food. In this study, these extracts were encapsulated in water-in-oil-in-water (w/o/w) nanoemulsions as a delivery system using a two-step high-energy emulsification method. PGPR and Span 20 were used as lipophilic emulsifiers for the primary w/o emulsion. The most stable w/o/w formulation with the least oil phase separation of 5% v/v consisted of w/o emulsion (15% w/w) and Tween 80 (1.5% w/w) as hydrophilic emulsifier. The formulation was characterized by a 189-nm mean droplet diameter, 0.16 polydispersity index, and –32 mV zeta potential. The freeze–thaw stability may be attributed to the combination of low w/o emulsion content and high Tween 80 concentration in the outer water phase of the w/o/w nanoemulsions used in this study. The IC50 values of the nanoemulsion and the red dragon fruit extract were similar. It means that the higher concentration of curcumin in the nanoemulsions and the lower IC50 value of temulawak extract ensured sufficient antioxidant activities of the w/o/w nanoemulsions.

Total Integration of the Sample Injection, Microdroplet Reaction, Phase Separation, Real‐Time Optical Detection, and Recovery of Diverse Silver–Gold Bimetallic Nanoalloys in a Continuous Process

AbstractMicrofluidic droplet generators have garnered great attention due to the uniformity, high‐throughput capability, and facile experimental setup. To maximize the potentials of droplet technology as a chemical/biological nanoliter‐scale reactor, the downstream processes such as separation of the aqueous and oil phase, real‐time monitoring of the products formed in droplets, and the final product recovery from the droplets is necessary. In this study, the droplet is utilized as a chemical reactor to synthesize a variety of Ag and Au bimetallic nanoalloys in a fully integrated microsystem including sample injection, a T‐junction droplet generator, droplet reaction, water–oil phase separation, real‐time UV–vis absorbance detection, and product recovery. The flow rate of the Ag nanoparticle (NP) solution and the HAuCl4 solution was tuned to generate different molar ratios of Ag and Au components. The in‐line UV–vis absorbance spectrometer displays a peak shift of the Ag/Au bimetallic alloys depending on the molar ratio of Ag/Au in the continuous process, enabling to judge the kind of the Ag/Au alloys in situ and collect a variety of Ag/Au nanoalloys. Thus, the desired nanomaterials can be obtained with minimal trial and error, saving time and cost.

Pickering emulsions of alumina nanoparticles and bola-type selenium surfactant yield a fully recyclable aqueous phase

We report a redox-responsive Pickering emulsion stabilized by a selenium-based surfactant and alumina nanoparticles, in which separation of oil phase without residual surfactant and recycling of the Pickering emulsifiers from aqueous phase is possible after demulsification.