Preparation of Water-in-Diesel Fuel Nanoemulsions Using High-Energy Emulsification Method and a Study of Some of Their Surface Active Properties

In this work, formations of water-in-diesel fuel nanoemulsions using water/mixed nonionic surfactant/diesel fuel system has been studied. The high-energy emulsification method was used to form three emulsions using different water contents: 5, 10, and 14% (v/v) namely; E1, E2, and E3, respectively. These nanoemulsions were stabilized with emulsifiers having different hydrophilic lipophilic balance (HLB), namely, Span 80 (HLB = 4.3), Emarol 85 (HLB = 11), and their mixture (SE) with HLB = 10. The effect of water on the droplet size formation has been investigated. The interfacial tension and thermodynamic properties of the individual and emulsifiers blends have been studied. The interfacial tension (γ) measurements at 30°C were used to determine the critical micelle concentration (CMC) and surface active properties of these emulsifiers. The water droplet sizes were measured by dynamic light scattering (DLS). From the obtained data, it was found that mean sizes between 19.3 and 39 nm were obtained depending on the water content and concentration of blend emulsifiers (SE). Also, the results show that the interfacial tension (γ) gives minimum value (10.85 mN/m) for SE comparing with individual emulsifier (17.13 and 12.77 mN/m) for Span 80 and Emarol 85, respectively. The visual inspection by transmission electron microscopy showed that the obtained results support the data obtained by dynamic light scattering.     

Formation of orange oil-in-water nanoemullsions using nonionic surfactant mixtures by high pressure homogenizer

The formation of nanoemulsions depends on the size of the droplets formed, the polydispersity and the difference in solubility and/or chemical potential between the small and large droplets. This article reports experiments to evaluate the formation of orange oil/water nanoemulsions in the presence of mixtures of nonionic surfactants, prepared in a high-pressure homogenizer. The surfactant mixtures were prepared to have different HLB values, by varying their type and concentration. The formation and stability of the nanoemulsions were evaluated as a function of the surfactant mixture used and also the processing conditions in the homogenizer. The size and distribution of the droplets formed, along with their stability, were determined in a Zetasizer Nano ZS particle size analyzer. The results showed that the optimal HLB range of the surfactant mixtures to obtain stable o/w nanoemulsions, independent of the processing conditions, is between 11 and 12. Better results were obtained with Unitol®L20/Unitol®L100 mixtures, in which the hydro-phobic surfactant causes a reduction in the interfacial tension and the hydrophilic surfactant promotes steric stabilization of the system.     

Effect of process parameters and methylcellulose supplementation on the properties of n-undecane emulsions

Study was made on the influence of processing parameters on droplet size during emulsification with an Ultra-Turrax homogenizer. Emulsions of undecane in water, stabilized with nonionic Igepals, were prepared at the optimum hydrophilic-lipophilic balance (HLB) of 11.5 and oil-to-water (O/W) ratio of 5/95; the sizes of emulsion droplets were measured at intervals from the commencement of emulsification. Results showed that the optimum emulsification conditions, as pertaining to minimum particle size, arose at 13 400 rpm and 20 minutes of Ultra-Turrax treatment. Additionally, effects exerted by the presence of methylcellulose, time and storage temperature on the emulsions were determined. Emulsions prepared at the optimal processing parameters revealed that the smallest particle sizes (lower than 200 nm) and the best emulsion stability were demonstrated at the oil/water ratios of 3/97 and 5/95, with 3% surfactant content, an HLB value of 10 to 11 and the storage temperature of 25°C, irrespective of the content of methylcellulose.     

Transport properties of alternative fuel microemulsions based on sugar surfactant

Electrical conductivity of fuel microemulsion composed of diesel, pentanol, water, and sucrose laurate as surfactant was investigated over a wide range of water contents varying from 0 to 90?wt% and temperature varying from 10°C to 50°C. Conductivity measurements were performed on samples, the composition of which lie along the one-phase channel using a conductivity meter. Activation energy of conduction flow was evaluated. The hydrodynamic radius as a function of temperature in the aqueous phase-rich region (90?wt%) was measured using the dynamic light scattering (DLS) method. The microstructure of the microemulsion was further investigated by NMR diffusometry by which the self-diffusion coefficients for water were determined at 25°C. Electrical conductivity increases with water content up to 40?wt% and the percolation threshold was observed, and then stabilizes between 40 and 80?wt% then decreases. Percolation threshold temperature at constant composition was monitored as 36°C for water contents below 80?wt% and as 34°C for water contents above that. As predicted by the conductivity measurements, the determined self-diffusion coefficients of water confirmed the structural transition from discrete W/O droplets to bi-continuous phase and finally to O/W droplet microemulsion.     

The influence of surfactant mixing ratio on nano-emulsion formation by the pit method

The formation of O/W nano-emulsions by the PIT emulsification method in water/mixed nonionic surfactant/oil systems has been studied. The hydrophilic-lipophilic properties of the surfactant were varied by mixing polyoxyethylene 4-lauryl ether (C12E4) and polyoxyethylene 6-lauryl ether (C12E6). Emulsification was performed in samples with constant oil concentration (20 wt%) by fast cooling from the corresponding HLB temperature to 25 degrees C. Nano-emulsions with droplet radius 60-70 nm and 25-30 nm were obtained at total surfactant concentrations of 4 and 8 wt%, respectively. Moreover, droplet size remained practically unchanged, independent of the surfactant mixing ratio, X(C12E6). At 4 wt% surfactant concentration, the polydispersity and instability of nano-emulsions increased with the increase in X(C12E6). However, at 8 wt% surfactant concentration, nano-emulsions with low polydispersity and high stability were obtained in a wide range of surfactant mixing ratios. Phase behavior studies showed that at 4 wt% surfactant concentration, three-liquid phases (W+D+O) coexist at the starting emulsification temperature. Furthermore, the excess oil phase with respect to the microemulsion D-phase increases with the increase in X(C12E6), which could explain the increase in instability. At 8 wt% surfactant concentration, a microemulsion D-phase is present when emulsification starts. The low droplet size and polydispersity and higher stability of these nano-emulsions have been attributed, in addition to the increase in the surface or interfacial activity, to the spontaneous emulsification produced in the microemulsion D-phase.     

A review of: “Nineteenth Century Attitudes: Men of Science (Chemists and Chemistry Series,Vol. 13)”. Sydney Ross. Kluwer Academic Publishers; Dordrecht, 1991. pp. xi+235. $69.00.

Abstract

The potential of polytetrafluoroethylene (PTFE) membranes as water‐in‐oil (W/O) emulsification devices was investigated to obtain uniformly sized droplets and to convert them into microcapsules and polymer particles via subsequent treatments. Uniform W/O emulsion droplets have not been achieved using glass membranes unless the membrane was rendered hydrophobic by treatment with silanes. If a PTFE membrane is capable of providing uniform droplets for a W/O emulsion, a coordinated membrane emulsification system can be established since glass membranes have been so successful for O/W (oil‐in‐water) emulsification. In order to examine the feasibility of PTFE membrane emulsification, O/W and W/O emulsion characteristics prepared using PTFE membranes were compared with those prepared by the conventional SPG (Shirasu porous glass) membrane emulsification method. A 3 wt.% sodium chloride solution was dispersed in kerosene using a low HLB surfactant. Effects of the membrane pore size, permeation pressure, and the type of emulsifiers and concentration on the droplet size and on the size distribution (CV, coefficient of variation) were investigated. The CV of the droplets was fairly low, and the average droplet size was correlated with the critical permeation pressure of the dispersed phase, revealing that the PTFE membrane could be used as a one‐pass membrane emulsification device. Low CV values were maintained with a Span 85 (HLB = 1.8) concentration, 0.2–5.0 wt.% and a range of HLB from 1.8–5.0. For a brief demonstration of practical applications, nylon‐6,10 microcapsules prepared by interfacial polycondensation and poly(acrylamide) hydrogels from inverse suspension polymerization are illustrated.     

Preparation of water-in-diesel oil nano-emulsion using nonionic surfactants with enhanced stability and flow properties

Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants (T6?+?S8) have been tested and the best possible combination of mixed surfactants is found at a surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB)?=?8.01, which resulted in smaller droplet size of 44.87?nm. A phase diagram study is performed to identify the zones of formation of transparent, translucent, and opaque emulsions (44?nm??27?m³?·?s^?1. Comparison of Ostwald ripening rate with other sets of surfactants obtained by different authors showed the lowest rate among them, indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the Newtonian behavior (1.0371?≤?n?≤?1.0826) over a wider range of shear rates (10–1000?s^?1) at different temperatures (25–40°C).     

Effects of sorbitan monooleate on the interactions between cyclopentane hydrate particles and water droplets

The effects of a typical anti-agglomerant, sorbitan monooleate (Span80), on the interactions between cyclopentane (CyC5) hydrate particles and water droplets were investigated using a micromechanical force (MMF) apparatus. The concentration of Span80 in CyC5 was ranged from 0.01?wt% to 1?wt%, and the experimental temperature was set at 1.5°C and 7°C, respectively. The results indicate that the absorption of Span80 on the droplet surface can render the interfaces more stable, preventing hydrate agglomeration. When the preload/contact force exceeds the strength of the interface (相似文献   

Evaluation of process conditions and characterization of particle size and stability of oil-in-water nanoemulsions

This article reports on the oil in water (o/w) nanoemulsions, which were prepared using a mixture of solvents (decane, toluene and cyclohexane) as oils and the mixtures of ethoxylated lauryl alcohols with various concentrations as surfactants with HLB values ranged from 10 to 12. The Ultra-Turrax (rotor-stator type) stirring and/or ultrasound processing were applied for varied processing times. The data show that the particle sizes in nanoemulsions prepared with ultrasound were smaller than those produced by stirring. The stability of these emulsions was, however, enhanced, when the mixtures were preliminary processed with the shearing agitator. The most stable nanoemulsions were obtained in 10 wt % surfactant mixture of the alcohols with HLB 11 in the shearing agitator.     

The effect of a lipophilic drug,felodipine, on the formation of nanoemulsions upon phase inversion induced by temperature variation

The correlation between a dispersed phase/dispersion medium interfacial tension σ at a storage temperature of 22°C and the dispersity and stability of oil-in-water miniemulsions, which result from temperature-induced phase inversion, has been revealed for hydrocarbon/polyoxyethylene(4)lauryl ether/water systems (in the presence and absence of felodipine) with the help of conductometry, tensiometry, and dispersion analysis. At σ < 3.5 × 10^–6 N/m, oil-in-water nanoemulsions, which have narrow monomodal particle size distributions and are stable for a month, are a fortiori formed. Felodipine has been shown to serve as a cosurfactant, which is incorporated into the adsorption layer of a basic stabilizing nonionic surfactant. Therewith, σ values increase and the temperature of phase inversion decreases, while the concentration of the basic surfactant in an optimal composition must be substantially reduced. A heptane/water nanoemulsion (droplet size of 75 nm) stabilized with a basic nonionic surfactant and Tween 80 exhibits a high solubilization capacity with respect to felodipine and ensures its efficient mass transfer through a model membrane.     

Formation of Concentrated Nanoemulsions by Extreme Shear

Abstract

We have systematically investigated the production of “nanoemulsions,” droplets of one liquid phase in another immiscible liquid phase that have diameters less than 100 nm. Our approach relies on a combination of extreme shear due to multipass, high‐pressure microfluidic injection and systematic control of the emulsion's composition. By repeatedly shearing a silicone oil‐in‐water emulsion in an inhomogeneous extensional shear flow, the multipass approach enables us to reduce the droplet polydispersity and average radius. Using dynamic light scattering, we study the changes in the average radius, ?a?, as a function of the number of passes, driving injection pressure (i.e., shear rate), droplet volume fraction, surfactant concentration, and droplet oil viscosity. The smallest nanoemulsion that we obtain has ?a?=18 nm. At large droplet volume fractions φ≥0.65, we observe phase inversion, rather than a reduction in the droplet size. This provides evidence that droplet coalescence can occur during extreme shear, even when a significant excess of a strongly stabilizing surfactant is present.     

Influence of Surfactants Synergism on the Adsorption Behavior at Air/Water and Solid/Water Interfaces

The influence of synergistic interaction between sodium dodecylsulfate (SDS) and N,N-dimethyldodecan-1-amine oxide (DDAO) on their adsorption at air/water and solid/water interfaces at 20°C is investigated. The critical micelle concentration values obtained from surface tension measurements indicated strong synergism between SDS and DDAO, according to regular solution model. The excess surface concentration (Γ) and the minimum occupied area by single and mixed surfactant monomers (A_min) at liquid/air interface were also calculated. The adsorption onto the activated charcoal and silica was then measured to find out the correlation between surfactant synergism and their adsorption at solid/water interface. The amounts of surfactant adsorbed onto 1 wt% activated charcoal follow the trend: SDS/DDAO > DDAO > SDS. SDS molecules do not adsorb onto 5 wt% silica substrate, while SDS/DDAO mixed system was found to have the highest adsorption behavior. The obtained indicate that SDS can be removed from water by mixing it with amphoteric surfactant.     

Structural Parameters of Mixed Nonionic Surfactants Microemulsions

In this study, we estimated the structural parameters of water/mixed nonionic surfactants/R (+)-limonene microemulsions. The mixed surfactants are sucrose laurate and ethoxylated mono-di-glyceride. U-type microemulsion region was observed in these systems. It was found that changes in the surfactants mixing ratio, surfactants contents and oil/water weight ratio in the microemulsions incite a considerable change in the aggregation number, core radius and interfacial area per mixed surfactants head groups in the formed microemulsions. The interfacial area per mixed surfactant head groups increases while the aggregation number decreases with the increase in the ethoxylated mono-di-glyceride mass fraction in the mixed surfactants. The For an oil/water weight content equals unity, the interfacial area per mixed surfactants head groups is constant for mixed surfactants contents below 35 wt%. For mixed surfactants contents above 35 wt% the interfacial area per mixed surfactants head groups decrease and stabilizes at the lower value. The aggregation number decreases with the increase in the mixed surfactants contents. The aggregation number decreases also with the increase in the oil/water weight ratio at fixed mixed surfactants content.     

表面活性剂HLB值与渣油乳化体系分散性及电学性质的关系研究

为了研究表面活性剂亲水亲油平衡值（HLB值）与渣油乳化体系分散性和电学性质的关系,采用粒径和粒径分布相结合的方法来评价乳化体系的分散性,利用电导率值的变化来反应体系电学性质的差异,以表面活性剂B和A复合成实验用渣油乳化分散剂来分散渣油加氢裂化水溶性盐,考察了表面活性剂HLB值对渣油包盐水体系的分散性和电学性质的影响。结果表明,随表面活性剂HLB值从小到大的变化,不同水溶性盐在同种油中的分散性和电学性质不同,同种盐在不同油中的变化也存在着差异。乳化体系的分散性及电学性质随着HLB值的增加呈非线性变化。     

Synthesis and surface properties of self-crosslinking core–shell acrylic copolymer emulsions containing fluorine/silicone in the shell

Stable emulsions of a core–shell acrylic copolymer (non-crosslinkable V0, and crosslinkable V2, V4, V6, and V8, where the numbers indicate the wt% of crosslinking agent based on the total acrylate monomer content) containing butyl acrylate (BA, 45 wt%), glycidyl methacrylate (GMA, 45 wt%), heptadecafluorodecyl methacrylate (PFA, 10 wt%), and various contents of crosslinking agent (vinyltriethoxysilane, VTES) were synthesized using a three-stage seeded emulsion polymerization process with a small amount of surfactant. The average particle size and viscosity of emulsions increased significantly with increasing VTES content. This study examined the effects of the VTES content on the surface/mechanical properties of self-crosslinked copolymer film samples containing a fixed acrylate monomer content to find the optimum VTES content. XPS showed that the film–air surface of the copolymer samples had a higher fluorine/silicone content than the film–dish interface. The tensile strength/modulus, thermal stability, and two Tgs (α and β Tgs) of the film samples increased significantly with increasing VTES content. The contact angle of the film samples increased with increasing VTES content up to approximately 6 wt%, and then decreased slightly. The optimum VTES content was approximately 6 wt% based on the total acrylate monomer content to obtain a high water/oil repellent coating material (V6) with the highest water/methylene iodide-contact angles (118.2°/81.8°) and lowest surface energy (18.4 mN/m).     

PREPARATION OF CLOUDY COCONUT OIL EMULSIONS CONTAINING DISPERSED Ti02 USING ATOMIZER

Food Grade Rutile TiO₂ was dispersed in coconut oil with the help of hydrophobic emulsifiers such as sorbitan esters and lecithin. The dispersed mixture was melted and blended with hydrophilic emulsifiers such as ethoxylated sorbitan esters and the preheated (60°C) blend was further sprayed by atomizer into cold water (20°C). The oil-in-water emulsions contained encapsulated TiO₂ in the internal phase. The technique is simple and allows preparation of stable emulsions with average droplet size of 1-10 microns.     

Properties of water-in-oil (W/O) nano-emulsions prepared by a low-energy emulsification method

Properties of water-in-oil (W/O) nano-emulsion formed by a low-energy emulsification method are described in this work. Nano-emulsions have been formed in water/mixed non-ionic surfactant/decane. Several mixtures of Span 20, Span 80, Tween 20 and Tween 80 were studied. Phase behavior studies and stability studies allowed to determine zones where nano-emulsions can be formed. Bluish and transparent W/O nano-emulsion with droplet sizes as low as 30 nm was formed. Nano-emulsion droplet size was measured by Dynamic Light Scattering. Nano-emulsions stability was studied by multiple light scattering and by dynamic light scattering. The results showed the evolution with time of the average radius droplet. The nano-emulsions prepared showed high kinetic stability for weeks, without phase separation, sedimentation or creaming. Nevertheless, their droplet size increased slightly over time. Stability studies show that nano-emulsion breakdown could be attributed to Ostwald ripening and coalescence mechanism, depending on the water concentration.     

Formation of water-in-oil (W/O) nano-emulsions in a water/mixed non-ionic surfactant/oil systems prepared by a low-energy emulsification method

W/O nano-emulsion formation by a low-energy emulsification method is described for the first time. The nano-emulsions have been formed in water/mixed Cremophor EL:Cremophor WO7 surfactant/isopropyl myristate systems at Cremophor EL:Cremophor WO7 ratios between 1:2 and 1:9, by slow addition of isopropyl myristate to surfactant/water mixtures. Phase behaviour studies have showed that the compositions giving rise to W/O nano-emulsions belong to multiphase regions, one of the phases being a lamellar liquid crystalline phase. The droplet size of the nano-emulsions at a fixed oil concentration of 85% and mixed surfactants/water ratio of 70/30 ranged from 60 to 160 nm as Cremophor EL:Cremophor WO7 ratio increased from 1:8 to 1:2. These nano-emulsions showed high kinetic stability. No phase separation was observed during 5 months in nano-emulsions of the water/Cremophor EL:Cremophor WO7 1:8/isopropyl myristate system with 85% oil concentration, although droplet size experienced an increase with time.     

Synthesis of Surfactants from Alkali Lignin for Enhanced Oil Recovery

With the cheap and abundant resource of alkali lignin as feedstock, surfactants for enhanced oil recovery were synthesized by amination and alkylation reaction of lignosulfonate. The effects of amination conditions, including the ratio of raw materials, amination reagent, temperature, and reaction time, on nitrogen contents and surface tension of the surfactants were investigated. The results showed that ethylenediamine was more suitable for amination, and the molar ratio of alkali lignin, ethylenediamine, and formaldehyde was 1:2:1.5 at 80°C for 5 hours. The structure of synthesized products was characterized by Fourier transform infrared spectrometry. The HLB value of synthesized product was 10. The interfacial tension between Daqing crude oil and synthetic water could be decreased to 10^?2 mN/m with synthesized surfactant and NaOH at 45°C. Moreover, the effects of molecular weight of surfactants on interfacial tension were also studied. The synthesized surfactant (M_w > 10,000) showed a better interfacial activity on Daqing crude oil.     

Study on Rheologic Properties and Molecular Configuration in the Mixed Systems of Polyacrylamide and a Gemini Surfactant

The rheological properties and the microconformations of the mixed system of hydrophobically modified polyacrylamide and a Gemini surfactant, O,O′-bis(sodium 2-lauricate)-p-benzenediol, in water, 5000 mg/L NaCl, 1.2 wt% NaOH, and 5000 mg/L NaCl with 1.2 wt% NaOH solutions were investigated, respectively. Scan electron microscopy of the samples prepared with the vacuum sublimation freezing–drying technique shows much more polymer aggregation information. The mixed system of polyacrylamide and an anionic surfactant, sodium dodecyl benzene sulfonate, was also investigated for comparison. The experimental results reveal that the rheological properties have a close relation with aggregation micostructure of the polymer. The Gemini surfactant is much more effective to affect the molecular interaction and aggregation of hydrophobically modified polyacrylamide, and thus has a higher viscosity increasing effect than the conventional surfactants.