Increase In Emulsifier Concentration Research Articles

Study on the kinetics of formation process of emulsion of heavy oil and its functional group components

Enhanced oil recovery (EOR) by in situ formation of oil-in-water emulsion in heavy oil cold production technology has received growing interest from the petroleum industry. We present an experimental study of emulsification of model oils prepared by heavy oil and its functional group compositions dissolved into toluene brought into contact with a surfactant solution. The effects of functional group composition, emulsifier concentration, temperature, pH and stirring speed on the emulsification rate of heavy oil was investigated. A second-order kinetic model characterizing the temporal variation of conductivity during the emulsification has been established. The results show that acidic and amphoteric fractions exhibit higher interfacial activity, larger emulsification rate constant and faster emulsification rate. With the increase of emulsifier concentration, the emulsification rate constant increase to the maximum value at a concentration of 0.05 mol/L before decreasing. Temperature increase benefits the emulsification rate and the activation energy of the emulsification process is 40.28 kJ/mol. Higher pH and stirring speed indicate faster emulsification rate. The heterogeneity of emulsions limits the accuracy of dynamic characterization of the emulsification process and the determination method of emulsification rate has always been controversial. The conductivity method we proposed can effectively evaluates the emulsification kinetics. This paper provides theoretical guidance for an in-depth understanding of the mechanism and application of cold recovery technology for heavy oil.

Effect of Emulsifiers on Quality Parameters of Coconut (<i>Cocos nucifera</i> L.) Milk Concentrate

Coconut milk was treated with emulsifiers, namely, Tween 80 (0.5% and 1.0%) and Tween 20 (0.25% and 0.75%) for preparing the coconut milk concentrate. Treated coconut milk was evaporated to reach desirable consistency more than 20% TSS. Increase in emulsifier concentration in the coconut milk not only reduced the time taken for product preparation, but also, controlled breakage of fat globules in coconut milk. Prepared coconut milk concentrate was analyzed for moisture, fat, pH, TSS and over run, sensory parameters like color, appearance, taste, texture, flavor and overall acceptability using 9-point Hedonic scale during 21 days of storage eat refrigerated conditions. Moisture, over run and TSS increased while fat and pH decreased during storage. Results showed that the concentrate prepared with different treatments were significantly different with each other at p≤0.05. Among all concentrate samples prepared, 0.5% Tween 80 emulsifier additions appeared to be the best treatment till 7th day of storage in terms of sensory parameters.

Hydroquinone loaded solid lipid nanoparticles comprised of stearic acid and ionic emulsifiers: Physicochemical characterization and in vitro release study

Solid lipid nanoparticles (SLNs) were successfully prepared using stearic acid and cationic/anionic emulsifiers by ultrasonication method. The model drug hydroquinone (HQ) which is used for the treatment of hyperpigmentation was loaded into SLNs. HQ loaded SLNs help to overcome drawbacks of hydroquinone including instability due to its rapid oxidation and its severe side effects on the skin. Six free SLN formulations (without HQ) and six HQ loaded SLN formulations were prepared using stearic acid and various concentrations (5 %, 10 % and 15 %) of cationic emulsifier cetyltrimethylammonium bromide (CTAB) and anionic emulsifier sodium lauryl sulphate (SLS). The detailed physicochemical characterization of SLNs was performed using a combination of light scattering, microscopic, calorimetric and spectroscopic techniques. All the prepared SLNs were in nanometer range (150–275 nm) and contain stearic acid in stable polymorphic form. The drug in vitro release behaviour from SLNs was studied using novel electrochemical method based on differential pulse voltammetry (DPV). HQ entrapment increases with increase in emulsifier concentration. CTAB stabilized SLNs displayed continuous prolonged release of HQ whereas, SLS stabilized SLN at higher concentration (15 %) gives burst release of HQ. The burst release can be correlated with smallest particle size of HQ-SLNs, lowest crystallinity and partitioning of drug into aqueous emulsifier phase at higher SLS concentration. Thus validated electrochemical DPV method proved to be highly applicable for quantification of HQ in SLN and release behaviour of HQ from SLNs.

Preparation of stable inverse emulsions of hydroxyethyl methacrylate and their stability evaluation by centrifugal coefficient

Several inverse emulsions were prepared with different hydrophilic-lipophilic balance (HLB) values using different water/oil ratios, temperatures and monomer and emulsifier concentrations by uniform stirring for more than 30 min. The stability of inverse emulsion was characterized by centrifugal coefficient. The emulsion form, either oil/water (O/W) or water/oil (W/O) was characterized by optical microscope and conductivity measurements. The results showed that HLB value, water/oil ratio and temperature could have an effect on the emulsion stability and emulsion form. When the HLB value of emulsifier is about 8.4, the water to oil ratio is about 1:1 and the temperature is at about 25 °C, inverse emulsion in the form of water in oil (W/O) was found to be the most stable. Here, the stablilty of emulsions was studied in relation to temperature and we found that 25 °C (room temperature) is the best for obtaining the most stable inverse emulsion, which is also most suitable for the redox initiation in this system. In the present study, we showed that temperature has a significant influence on the structure morphology and stability of inverse emulsion and hence, it is necessary to select the appropriate reaction temperature for inverse emulsion polymerization. This is a novel result. A decrease of the content of hydroxyethyl methacrylate in aqueous solution with an increase of emulsifier concentration in emulsion was found to elevate the stability of inverse emulsion. The addition of trace electrolytes in the emulsion, however, led to greatly reduced stability of the inverse emulsion.

Concentration of resveratrol at the oil–water interface of corn oil-in-water emulsions

Accumulation of polyphenolic antioxidants at the oil–water interfaces of lipid-based emulsions is crucial to improve their oxidative stability. Polyphenolic antioxidants are added to lipid-based emulsions to minimize the lipid peroxidation reaction, a radical reaction that produces harmful products and undesirable off-flavors, and because of their benefits in human health. Antioxidants react with the lipid radicals at the oil–water interface of emulsions, inhibiting or minimizing the lipid oxidation reaction, increasing the oxidative stability of the emulsion, and their efficiency in inhibiting the oxidation of lipids strongly depends on their interfacial concentration. In this work we have evaluated the accumulation of trans-resveratrol (3,4′,5-trihydroxystilbene, TRES) in the interfacial region of a model food-grade emulsion composed of stripped corn oil, acidic water and Tween 20 and analyzed its variation with the surfactant concentration. Results show that TRES distributes between the three regions, but more than 85% of TRES is located in the interfacial region and only a small fraction in the oil and aqueous regions. An increase in emulsifier concentration promotes the incorporation of TRES into the interfacial region, however, its interfacial concentration, which is much higher than the stoichiometric concentration, decrease because of the increase of the interfacial volume. Results obtained should contribute to a better understanding of the antioxidant efficiency in inhibiting lipid oxidation and to the development of new strategies to prepare healthier and more nutritional foods with longer shelf-lives.

Protection of emulsified polyunsaturated fatty acids against in vitro ruminal biohydrogenation by polyphenol oxidase: Characterization of the cross-linked emulsion

In the current study, linseed oil emulsions were cross-linked by polyphenol oxidase to study the effect of emulsion characteristics on the protection of polyunsaturated fatty acids against biohydrogenation by rumen bacteria in vitro. Polyphenol oxidase (PPO) catalyzes the oxidation of diphenolic substrate to o-quinones which are reactive towards amino- and thiol- groups on proteins, forming a complex of covalently bound protein cross-linked by protein-bound phenols (PBP). Such cross-linking of protein-stabilized emulsions was shown to yield high in vitro ruminal protection of polyunsaturated fatty acids before, by addition of PPO extract and diphenolic substrate to protein-stabilized emulsions. The current study examined the relationship between characteristics of cross-linked emulsions and in vitro ruminal protection by evaluation of two hypotheses: protection efficiency would be impaired when 1) the amount of PPO in the emulsion decreased or 2) the amount of non-adsorbed protein in the emulsion increased. Hence, in a first experiment, emulsions containing the same protein concentration and varying amounts of PPO extract (0,2-0,8 g/g) were analyzed, while in experiment 2, emulsions containing varying amounts of non-adsorbed protein and a similar amount of PPO extract (0,8 g/g) were investigated. In the latter experiment, variation in non-adsorbed protein was obtained by altering the emulsifier concentration (10 or 0 mg/g whey protein isolate) and/or removal of the majority (>90%) of the non-adsorbed protein after emulsion preparation, i.e. washing of the emulsion, before addition of PPO extract. In vitro ruminal biohydrogenation was evaluated after 24 h in a rumen-simulated environment containing rumen inoculum. Results of experiment 1 showed protection efficiency decreased for decreasing amounts of PPO extract. Additionally, in vitro ruminal protection was found to be positively correlated to mean droplet size, protein load and proportion of PBP in the free protein fraction of the emulsions after cross-linking, while proportion of PBP in the adsorbed protein layer did not differ between treatments. In experiment 2, an increase in emulsifier concentration from 10 to 50 g/g WPI lowered the amount of PBP in both protein fractions. Washing of 50 mg/g WPI emulsions, enhanced in vitro ruminal protection of 18:3n-3 and 18:2n-6 and increased the proportion of PBP in both free and adsorbed protein. Moreover, protein load and the amount of total adsorbed PBP were positively affected by washing. Comparison of emulsions with similar protein load between experiments showed in vitro ruminal protection efficiency increased for higher proportions of PBP in the adsorbed protein layer. Moreover, an excess of PBP on the possible binding positions on the adsorbed protein seemed to promote in vitro ruminal protection efficiency.

Physical and Oxidative Stability of Flaxseed Oil-Fructooligosaccharide Emulsion

The objective of this study was to develop a practical and simple method to produce flaxseed oil emulsion with fructooligosaccharide (FOS). Effects of types and concentrations of emulsifiers and the ratio of dispersed phase to continuous phase in the emulsions on the physical properties were tested. Among tested five emulsifiers, the emulsion containing decaglycerol monolaurate (HLB 15) was the most stable. The concentrations of decaglycerol monolaurate above 2% (w/w) were able to form stable emulsions. Increase in emulsifier concentration increased viscosity and decreased particle size, showing pseudoplastic flow. All the tested ratios (3:7, 4:6, 5:5, 6:4, 7:3 and 8:2) of the flaxseed oil and FOS except for 8:2 formed stable emulsions. Oil in the emulsion was less oxidized than flaxseed oil itself. These results suggest that the addition of FOS to the continuous phase of flaxseed oil emulsion may increase the physical and oxidative stability of the emulsion. Practical Applications Emulsions are widely used in food, cosmetic and pharmaceutical industries. The objective of this study was to develop a practical and simple method to produce flaxseed oil emulsion with FOS to increase its value developing new n-3 fatty acid products for functional food and nutraceutical applications. The flaxseed oil-FOS emulsion is less readily oxidized than flaxseed oil itself. These results suggest that flaxseed oil-FOS emulsion may increase utilization of flaxseed oil in aqueous food systems and could supply n-3 fatty acids to the consumers who require them.

Effects of Emulsifier Concentration on Polymer Particle Size in Emulsion Polymerization of Styrene

The variation trend of polymer particle size under different emulsifier concentrations in emulsion polymerization of styrene were investigated in this paper. The results show that the particle number increases and particle size decreases with the increase of emulsifier concentration. But the particle size growth is controlled by the rate of the monomer migration from water medium to the growing micelles.

Distribution of catechol in emulsions

In this work, we have evaluated the effects of emulsifier concentration on the distribution of catechol (1,2‐dihydroxybenzene, CAT) in food‐grade emulsions composed of stripped corn oil, acidic water, and Tween 20. Auxiliary experiments in binary stripped corn oil–water mixtures, in the absence of emulsifier, showed that CAT is both oil and water soluble (partition constant = 0.34). Addition of Tween 20 to prepare kinetically stable emulsions creates an interfacial region, and the distribution of CAT is now described by two partition constants, that between the oil and interfacial region, , and that between the aqueous and interfacial region, . These partition constants were determined in the intact emulsion by employing a kinetic method that exploits the reaction between the hydrophobic 4‐hexadecylbenzenediazonium ions, 16‐ArN2+, and CAT. Results show that CAT distributes between the three regions. At emulsifier volume fractions of ΦI = 0.005, CAT is predominantly located (~61%) in the aqueous region, about 26% is in the interfacial region, and only a small fraction (~13%) in the oil region. An increase in emulsifier concentration promotes the incorporation of CAT to the interfacial region up to ~70% at ΦI = 0.037. Results obtained should contribute to a better understanding of the antioxidant efficiency in inhibiting lipid oxidation and to the development of new strategies to prepare healthier and more nutritional foods with longer shelf life. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of emulsifier type, pH and iron on oxidative stability of 5% fish oil‐in‐water emulsions

The effect of using different emulsifiers on lipid oxidation in 5% w/w fish oil‐in‐water emulsions was investigated. Emulsifiers included two of milk protein origin (whey protein isolate (Whey) or sodium caseinate (Cas)), soy lecithin (Lec) or emulsifiers high in milk phospholipid (20 or 75%). Forty different emulsions were produced with the five different emulsifiers. For each emulsifier, emulsions were prepared at two concentrations (0.2 and 0.75 wt%) at pH 3 or 7 and with or without added iron. Emulsions were stored in closed bottles in the dark at RT (20°C) for up to 7 days (with added iron) or 42 days (without added iron). Physical parameters and oxidative stability of the emulsions were investigated by analysis of particle size, zeta potential, primary and secondary oxidation products. Increase in emulsifier concentration generally increased the oxidative stability. Type of emulsifier and physical conditions affected the physical and oxidative stability of the emulsions. A general observation was that emulsions produced with the milk protein based emulsifiers were more oxidatively stable compared with the other emulsions.Practical applications: The overall conclusion from this study was that the oxidative stability of 5% o/w emulsions depended on both emulsifier type, concentration, pH and iron content. An analogous conclusion is most likely also valid in more complex food emulsions with similar or higher lipid contents such as milk drink, dressing, etc. Hence, in such foods the emulsifier and the emulsifier concentration should be carefully chosen in order to minimise lipid oxidation. However, milk protein‐based emulsifiers could be a better choice than emulsifiers with higher content of phospholipids independent of emulsifier concentration, pH and iron content.

Optimization of Phytosterols Dispersion in an Oil/Water Emulsion Using Mixture Design Approach

Major problems related to enrichment of products with phytosterols are high melting temperature, chalky taste and low solubility in water phase. Dispersion of phytosterols in an emulsion was optimized using a mixture design with four components (phytosterols, emulsifier, soy oil, and water). It was found that the particle size of the dispersed phase decreased with the increase in emulsifier concentration. The appearance viscosity was increased with decreasing particle size. The stability of these emulsions could be correlated with the decrease in surface tension and particle size by using oil and emulsifier as components of oil phase.

Effects of emulsifier hydrophile–lipophile balance and emulsifier concentration on the distributions of gallic acid, propyl gallate, and α-tocopherol in corn oil emulsions

We evaluated the effects of the hydrophile–lipophile balance (HLB) and emulsifier concentration on the distribution of the antioxidants gallic acid (GA), propyl gallate (PG), and α-tocopherol (TOC) between the aqueous, interfacial, and oil regions of food-grade emulsions composed of stripped corn oil, acidic water, and a mixture of the non-ionic surfactants Tween 20, 40, 80, and Span 20. The distribution of the antioxidants (AOs) is described by two partition constants, that between the oil-interfacial region, POI, and that between the aqueous and interfacial region, PWI, of the emulsions. The partition constants were determined from the kinetic analyses of the variation in the observed rate constant, kobs, for the reaction between the AOs and the hydrophobic 4-hexadecylbenzenediazonium ions, 16-ArN2+, with the emulsifier volume fraction. The effects of emulsifier HLB on the second-order rate constants in the interfacial region kI were also evaluated for each antioxidant. Results show that an increase in emulsifier concentration promotes the incorporation of AOs to the interfacial region of the emulsions, so that at surfactant volume fractions of 0.04, more than 90% of GA and PG and more than 50% of TOC are located in that region. A decrease in the HLB favors the incorporation of PG and TOC to the interfacial region of the emulsions but has a negligible effect on the fraction of GA in that region. The %AOs in the interfacial region of the emulsions does not correlate with the polarity of the antioxidant, so that GA and PG are predominantly located in the aqueous–interfacial regions of the emulsion rather that in the oil droplet interior; meanwhile, TOC is mostly located in the oil-interfacial regions. Results should aid to understand how antioxidants are distributed in food-grade emulsions and their relative efficiency in inhibiting lipid oxidation.

Studies on the particle size control of gelatin microspheres

A series of gelatin microspheres (GMs) were prepared through emulsification-coacervation method in water-in-oil (w/o) emulsions. The influence of preparation parameters on particle size, surface morphology, and dispersion of GMs was examined. The studied preparation parameters include concentration of gelatin solutions, concentration of the emulsifier, w/o ratio, emulsifying time, stirring speed, and so on. The surface morphology, dispersion, and particle sizes of GMs were determined by the scanning electron microscopy (SEM), SemAfore 4 Demo software, and particle size distribution graphic charts. The experimental results indicated that increasing the concentration of gelatin solution would increase the particle size of GMs. When the solution concentration increased from 0.050 to 0.200 g/mL gradually, the particle size increased correspondingly. The relationship between the two quantities was linear. On the contrary, increasing the concentration of the emulsifier would decrease the particle size of GMs. Furthermore, the particle size reduced quickly at initial time and slowed down latterly. With the increase of emulsifier concentration from 0 to 0.020 g/mL, themean diameters ofGMsdecreased from 17.32 to 5.38 μm. However, the particle size dwindled slowly when emulsifier concentration was higher than 0.020 g/mL. The excellent result was obtained with the condition of 0.050 g/mL of emulsifier concentration, 0.100 g/mL of gelatin solution concentration, 1/5 of w/o ratio, 10 min of emulsifying time, and 900 r/min of the stirring speed. The GMs prepared at this condition had the smallest sizes, the narrowest size distribution, the best spherical shape, and fluidity. The w/o ratio has the same influence on particle size of GMs as that of gelatin solution concentration. With the increase of w/o ratio, the average particle sizes increased linearly, and the surface of microspheres become smoother as well. It is supposed that w/o ratio can be used to change the diameters and surface morphologies of GMs. The emulsifying time has little influence on the mean diameters of GMs, but it affects the dispersion of GMs apparently. When the emulsifying time was shorter than 5 min, the GMs had bad dispersion. After increasing the emulsifying time to 13 min, the dispersion of GMs changed greatly, whereas the dispersion of GMs became bad again when the emulsifying time was longer than 13 min. According to the experimental results, 13 min was considered to be the best emulsifying time. The stirring speed has the similar influence on GMs’ morphologies as that of emulsifying time. Slow stirring rate made large size distribution and bad spherical shape of GMs; excessive stirring speed results in aggregation among GMs likewise. The smaller size distribution and better spherical shape of GMs were observed under the stirring rate between 500 and 1500 r/min by SEM. In conclusion, increasing the concentration of gelatin solution or w/o ratio would increase the particle sizes of GMs, increasing the concentration of the emulsifier would decrease the sizes of GMs at proper emulsifying time, and stirring speed would get the best spherical shape of GMs. These are the basic laws governing the design and manufacture of the GMs.

Capillary Flow and Rheology Measurements on Chocolate Crumb/Sunflower Oil Mixtures

ABSTRACT: Rates of penetration of sunflower oil into beds of 3 types of chocolate crumb have been measured and the results analyzed using the Washburn‐Rideal theory. The data show that the rates are a function of both the specific surface area of the crumb particles and their surface composition. Addition of an emulsifier to the oil reduces the penetration rate into the crumb made with full‐cream milk powder, whereas for crumbs containing skimmed‐milk powder, rates go through a maximum with increase of emulsifier concentration. Rheological data for dispersions of crumb in oil were fitted to the Casson equation. An inverse correlation was found between penetration rates and Casson yield values.

Influence of nonionic emulsifiers on the properties of vinyl acetate/VeoVa10 ® and vinyl acetate/ethylene emulsions and paints

This paper presents results on the influence of the nonionic surfactant on the properties of vinyl acetate/VeoVa10 ® and vinyl acetate/ethylene emulsions and paints made thereof. Emulsions were prepared in which the concentration of the nonionic surfactant and its degree of ethoxylation were varied. An increase of the nonionic emulsifier concentration and of the length of the ethylene oxide chain leads to dispersions with smaller particles and higher viscosities. Using these emulsions as binders in high pigmented paints, it was observed that the pigment binding capacity of the interior paints goes through a maximum which is located at a emulsifier concentration of about 2–3% and at a degree of ethoxylation of 17–28 mol ethylene oxide (EO). In (semi-) gloss paints, the gloss of the paint films improves with an increase of the emulsifier concentration and reaches a constant value at around 4% or a degree of ethoxylation of ca. 17 EO-moieties per molecule. The blocking of the films shows a drastic increase at a concentration above 4% and at a chain length of greater than 17 EO-moieties.

Influence of Protein Emulsifier Interfacial Properties on Oil-in-Water Emulsion Stability

ABSTRACTThe purpose of this study was to determine whether the interfacial properties of emulsifier films could be related to emulsion stability and therefore be used as stability predictors using Bovine serum albumin (BSA) as a model oil-in water (o/w) emulsifier. Soybean o/w emulsions were prepared by ultrasonication, emulsion droplet interfacial charge was determined by microelectrophoresis, droplet size distribution was measured using an Accusizer, and centrifugal stress was studied using an ultracentrifuge. Real time, thermal kinetic, and centrifugal stress accelerated stability tests were performed. Stability data obtained from centrifugal stress tests followed the same trends as real time stability data and these data were in general agreement with stability predictions made based on interfacial properties. The thermal kinetic accelerated tests were not predictive of stability, because emulsion breakdown was rapid and did not allow differentiation between the emulsions. Emulsion stability increased with an increase in emulsifier concentration (emulsions prepared at 2% w/v BSA had not cracked at 60 days, whereas those prepared at 0.1% w/v had cracked by 30 days), increase in ionic strength (emulsions prepared at an ionic strength of 1 mM had cracked by 60 days, whereas those prepared at an ionic strength of 10 mM had cracked by 90 days), and decrease in temperature (emulsions prepared at 37 and 60°C had cracked by 5 days, whereas those prepared at 5 and 25°C had not cracked at 60 days). There was no significant change in stability for emulsions prepared at pH 5.3 and pH 7.4. The addition of dextran sulfate improved emulsion stability, whereas the addition of acacia decreased stability. Emulsions prepared with BSA alone cracked by 90 days, those prepared with BSA and acacia cracked by 30 days, and those prepared with BSA and dextran sulfate had not cracked at 90 days. Interfacial properties were useful in predicting emulsion stability.

DNA encapsulation by an air-agitated, liquid-liquid mixer

Smooth and spherical alginate microspheres and nylon-membrane bound microcapsules were formed in an air-agitated, liquid-liquid mixer by emulsification/internal gelation and interfacial polymerization respectively. The mean diameter of the alginate microspheres ranged from 100 to 800 microm, and was controlled by process modifications. Increase in emulsifier concentration, gas flowrate, and emulsification time resulted in smaller microsphere size as did a decrease in liquid height. Increase in the dispersed phase viscosity resulted in a longer emulsification time required for approaching a minimum microsphere size. Microspheres could be formed with the proportion of dispersed phase approaching 30%. The yield of alginate microspheres was 70%, with losses attributed to incomplete recovery during washing and filtration operations. The yield of DNA encapsulation within the fraction of recovered microspheres, was 94%. The small loss was thought to occur by surface release during the washing of the microspheres. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 464-470, 1997.

Comparative emulsifying properties of sodium caseinate and whey protein isolate in 18% oil in aqueous systems

SummaryBoth whey protein isolate (WPI) and Na caseinate gave similar emulsion capacity-concentration profiles at pH 7. The emulsion capacity of aqueous solutions of WPI was relatively independent of pH while the values for caseinate fell in the isoelectric region. Saline (7·59 g/1) compared with aqueous solutions improved emulsion capacity, particularly above pH 7. At low concentration, WPI had greater emulsifying capacity and gave finer globule dispersion than sodium caseinate. Increase in emulsifier concentration, within a certain range, increased stability, improved dispersion and reduced capacity. Ethanol up to about 20% w/w improved the emulsion capacity of both proteins while at 50% the phases separated. Heat treatment (> 65 °C) of WPI solution before emulsion formation impaired capacity and stability. Heat treatment of preformed WPI emulsions did not have the same effect. Na caseinate and WPI each formed a thin continuous layer of relatively uniform thickness over the oil globule surfaces while denatured WPI appeared aggregated and relatively unevenly distributed at the oil-aqueous interface.

Absorption and Translocation of Sethoxydim with Additives

Experiments were conducted to determine14C absorption and translocation by oat (Avena sativaL. ‘Lyon’) foliarly treated with14C-sethoxydim {(2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one)} and various additives. Safflower (Carthamus tinctoriusL.), soybean [Glycine max(L.) Merr.], linseed (Linum usitatissimumL.), and sunflower (Helianthus annuusL.) oil all similarly increased foliar absorption and translocation of14C more than palm oil (Elaeis quineensisJacq.) but less than petroleum oil, when applied without an emulsifier. An emulsifier in the oil additive tended to enhance14C absorption and translocation more in soybean oil than petroleum oil so that14C absorption and translocation were similar with both oils containing emulsifiers. Absorption and translocation of14C tended to increase more with an increase in emulsifier concentration in soybean oil than in petroleum oil but not beyond 15% with either oil. Percentage of14C absorbed and translocated from14C-sethoxydim applied to oats increased as the amount of soybean oil applied increased from 2.3 to 4.6 L/ha, but the increase was less for sethoxydim at 0.87 kg ai/ha than at 0.03 or 0.17 kg ai/ha.

Evaluation of emulsion stability. Effect of Tween group emulsifiers on stability of o/w type emulsions.

Examinations were made on the effect of Tween group emulsifiers, with combination of Span-20 and Tween-81 among them, to discuss the required HLB in detail, for o/w type emulsions with the use of various measurement methods. Oil-in-water emulsions were prepared containing 45% of dispersed phase. The emulsifiers used were commerical grade nonionic surfactants of four Tweens and Span-20, and the oil used was a mineral oil. Emulsion was formed by agitation, and emulsion stability was measured with four apparatuses, measuring cylinder, Coulter counter, turbidimeter, and rheometer. Following results were obtained, 1) The rate of separation was affected largely by the kind of emulsifiers, which increased in the order of Tween-81, Tween-81+Span-20, Tween-85, Tween-20, and Tween-21. 2) The o/w emulsion showed the maximum value of droplet number at characteristic HLB value equal to 10.0. 3) Viscosity of the emulsion increased with the increase of emulsifier concentration.