Design, Rheology and Physicochemical Characterizations of Oil-in-water Emulsions Stabilized by Waxy Starch Derivatives

Simple emulsions (o/w) stabilized by octenyl succinic anhydrous (OSA) starch were studied. They were characterized by the evaluation of the rheological and physicochemical properties and, the observation under the light microscope in combination with granulometric analysis after formulation. The obtained results demonstrated the effects of the amount of OSA starch on the variation of the diameter of particles, stability of emulsions and their rheological behavior. The best characteristics were found in the emulsion with a ratio 40/60 (o/w) at high OSA starch concentration, because the substitution of the oil phase by the network created by the chains of the modified polysaccharides which could be the major factor in stabilisation of emulsions

Investigation of Combined Effects of Xanthan Gum,Sodium Dodecyl Sulphate, and Salt on Some Physicochemical Properties of Their Mixtures Using a Response Surface Method

Aqueous solutions containing sodium dodecyl sulphate, xanthan gum, and salt were characterized by ionic conductivity, viscosity, and surface tension methods. A preliminary experimental study was performed to evaluate the effect of the mixture compositions on the surface behavior of the mixed polymer/surfactant systems under different solution conditions. An experimental design using response surface method (RSM) was then applied to assess factors interactions and empirical models regarding the physicochemical responses variables (i.e., conductivity, surface tension and viscosity). The main effects of the three independent factors: SDS concentration (x1), NaCl concentration (x2) and xanthan concentration (x3) were determined using in particular a D-optimal design. The results show an important effect of the factors on responses; they also indicate that the synergetic action of surfactant, electrolyte and biopolymer greatly influences these properties. Analysis of variance (ANOVA) showed high variance coefficient (R 2 ) values, thus, ensuring a satisfactory adjustment of the second-order regression model with the experimental data

Determination of micellar system behavior in the presence of salt and water-soluble polymers using the phase diagram technique

The application of micellar systems has been growing during the last years because of their importance in various practical situations. Continued development of their application is necessary. If the principal economic interest of microemulsions is for some time enhanced oil recovery, the following also have significant applications such as pharmaceutical preparations, painting, and products for engine lubrication. The effect of variation in composition of anionic surfactants (α oleifin sulfonates) and the presence of a water-soluble charged polymer (Xanthan gum) and an uncharged polymer [poly (ethylene glycol)] on the phase behaviour of pseudo- ternary systems of water–oil surfactants was investigated. Several domains were observed when the composition of surfactants and cosurfactants (e.g., pentanol) in a mixture is varied. The appearance of these domains in the phase diagram has been attributed to the formation of different Winsor systems

Hydrodynamique et physico-chimie des ecoulements diphasiques dans les conduits capillaires

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Strukturna, fizikalno-kemijska i termička svojstva voštanog kukuruznog škroba modificiranog octenil sukcinil anhidridom

The aim of current work was to carry out a fine characterisation of the structural, physicochemical, and thermal properties of octenyl succinic anhydride (OSA)-modified waxy maize starch known under the marketed name Gel ‘N’ Melt™. Both Fourier transform infrared spectroscopy and proton nuclear magnetic resonance analyses revealed the presence of new absorption bands and confirmed the structure of OSA-modified starch in comparison with those of native starch. The results of proton nuclear magnetic resonance analysis were consistent with those obtained using the titration method. The molecular weight obtained was regarded as higher than those found for other starch modified sources; an inverse correlation between the degree of substitution and the molecular weight was deduced: a decrease in the degree of substitution was followed by an increase in the molecular weight. In addition, X-ray diffraction and scanning electron microscopy revealed the loss of the ordered A-type crystalline structure, which is characteristic of polymers with low degree of substitution. Also, a coexistence of individual and aggregate particles was observed, supported by the extent of the fusion of grains. These results were corroborated by thermal analysis experiments, which showed a total loss of the crystallinity of the heated grains. This work is licensed under a Creative Commons Attribution 4.0 International License.Ovaj rad imao je za cilj provesti detaljnu karakterizaciju strukturnih, fizikalno-kemijskih i termičkih svojstava voštanog kukuruznog škroba modificiranog octenil sukcinil anhidridom (OSA), poznatog pod tržišnim imenom Gel ‘N’ Melt™. Analize infracrvenom spektroskopijom s Fourierovom transformacijom i protonskom nuklearnom magnetskom rezonancijom otkrile su prisutnost novih apsorpcijskih vrpci s obzirom na izvorni škrob. Rezultati dobiveni protonskom nuklearnom magnetskom rezonancijom bili su u skladu s rezultatima dobivenim titracijom. Uočena je viša molekulska masa nego kod modificiranog škroba dobivenog iz drugih izvora. Utvrđeno je da postoji inverzna korelacija između stupnja supstitucije i molekulske mase: smanjenjem stupnja supstitucije dolazi do povećanja mase. Osim toga, rendgenska difrakcijska analiza i skenirajuća elektronska mikroskopija otkrili su gubitak uređene kristalne strukture tipa A, što je karakteristično za polimere s niskim DS vrijednostima. Također, uočena je koegzistencija pojedinačnih i združenih čestica. Rezultati su potvrđeni toplinskom analizom koja je pokazala potpuni gubitak kristalnosti zagrijanih zrna. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Synthesis, physicochemical, structural and rheological characterizations of carboxymethyl xanthan derivatives

International audienceThe aim of this work was to synthesize a carboxymethylated xanthan (CMXG) via an etherification reaction between different ratios (2, 4, and 6) of xanthan gum (XG) and monochloroacetic acid (MCAA) using the Williamson synthesis method. The synthetized products were characterized in terms of their physico-chemical and rheological properties. Both FTIR and proton nuclear magnetic resonance (H1 NMR) analyses confirmed the grafting of carboxymethyl groups on xanthan hydroxyl groups. The obtained results demonstrated that the degree of substitution was proportional to the chloroacetic acid and xanthan gum ratios. The obtained carboxymethyl derivatives presented greater hydrophilicity and lower molecular weights with increasing degrees of substitution than native xanthan gum. The rheological study revealed that the viscosity of the CMXG derivatives decreased with the degree of substitution and with the conservation of the shear-thinning and weak gel behaviours. The flow curves suggested the existence of two different populations of particles consisting of CMXG particles with a smaller average size and a second population formed by the residual fractions of native XG particles. It was also found that the elastic modulus of XG was largely higher than that of the CMXG derivatives and decreased with increasing DS. For the CMXG derivatives, two regions of viscoelastic behaviour were observed, which were separated by a crossover point corresponding to the critical frequency and relaxation time, i.e., the time required for stress relaxation

Production and characterization of biosurfactant by free and immobilized cells from Ochrobactrum intermedium isolated from the soil of southern Algeria with a view to environmental application

In this paper, biosurfactant production by free and immobilized cells of Ochrobactrum intermedium has been studied. This bacterium strain was isolated from an Algerian crude oil-contaminated soil; hexadecane was used for the production as the sole carbon and energy source. The process was monitored by measuring the surface tension and emulsification index E24 for one week at 37 °C and neutral pH. For the production by immobilized cells, the concentrations of sodium alginate, calcium chloride and biomass were optimized. Results showed that O. intermedium entrapped in calcium alginate beads is able to preserve its viability and produce biosurfactants but with an effect on the production kinetics due to diffusional limitations of the alginate beads with greater stability with up to 75%. The product biosurfactant reduced the surface tension below 33 and emulsification index were 68%–93% after 48 and 72 h with free and immobilized cells, respectively. Also, the product belongs to the family of glycolipids and showed stability in a wide range of pH (2–12), temperature (25–120 °C), and to high salinity. Both products by strain O. intermedium, based on spectral features, have a chemical structure identical to that of glycolipids. The production yield of biosurfactant versus concentration of the hexadecane is 1292 g/g. Second, the surfactants are able to promote the solubility of polycyclic aromatic hydrocarbons (PAHs). Results show that the use of biosurfactant, produced by the isolated bacterial strain O. intermedium, obtained a better solubility of naphthalene and phenanthrene

Ultrafiltration d'émulsions huile-eau et de microémulsions de cyclohexane par un système à disque rotatif

La séparation de la phase huileuse à partir d'effluents huile-eau comportant des émulsions secondaires est très difficile par les procédés traditionnels et nécessite l'emploi de l'ultrafiltration. Des émulsions huile-eau contenant 2 et 4 % d'huile ont été ultrafiltrées à l'aide d'un prototype de filtration dynamique comportant un disque tournant à grande vitesse près d'une membrane de 50 kDa de 190 cm2 de surface. La turbidité de la solution initiale à 4 % (21 900 NTU) chute à 2 NTU dans le perméat après 15 min de filtration, ce qui représente une rétention de 99,5 % de l'huile. Les flux de perméat augmentent avec la vitesse de rotation du disque pour atteindre environ 90 l.h-1.m-2 à 2000 tr.min-1 à 24 °C. L'ajout d'ailettes de 6 mm de hauteur permet de doubler le flux de perméat à la même vitesse. Les microémulsions sont constituées de 4 à 20 % de cyclohexane, 0,5 à 16 % de 2-butanol et de 0,25 à 8 % de dodecyl sulfate de sodium (SDS) dans de l'eau pure. Les flux de perméat, très élevés (200 l.h-1.m-2) à 2000 tr.min-1 avec un disque lisse pour la solution la plus diluée chutent à 15 l.h-1.m-2 pour la plus concentrée. L'ajout d'ailettes permet de doubler ces flux

Surfactants Synthesis Using Petroleum Fractions and Crude Oil: Application in Microemulsion Formulation

International audienceSurfactant synthesis was realized from Algerian crude oil and petroleum fractions. To predict the composition (wt%) in paraffins, naphtenes, and aromatics, the crude oil and petroleum fractions were first characterized using the n-d-PA empirical method of Robert. The characterization showed a good level in aromatics compounds which give high yield in the sulfonation reaction by oleum. The synthesized surfactants were characterized by spectroscopic techniques (UV, FTIR) and by critical micelle concentration (CMC), Krafft temperature, solubility (in aqueous and in salt solution), molecular weight, and matter actives (%) measurements. The formulation of microemulsion using synthesized surfactant from plat format petroleum fraction showed a Winsor III type system. The effect of salinity demonstrates the existence of an optimal value of NaCl concentration for which the interfacial tension takes the lowered value (10−4 mN/m). Viscosity measurements confirm that the formulated microemulsion has a Newtonian behavior