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 the Effects of Cellulose Derivatives on the Kinetics of Drug Release from Cellulose-Based Hydrogel Using a Response Surface Method

The aim of this work was to investigate the effects of the nature and concentration of cellulose derivatives on the release kinetics of ibuprofen from hydrogel matrices using a response surface method (RSM). A series of cellulose derivatives, as methyl, hydroxyethyl, hydroxypropyl and hydroxypropyl methyl celluloses (MC, HEC, HPC and HPMC) were used as polymer platforms and their impacts on drug release were studied and compared to those obtained with a reference formulation prepared with HEC. It was shown that the use of HPMC in the gel formulation contributes to the improvement of drug release and consequently its biodisponibility. Indeed, the increase in HPMC concentration forms a controlled system release because polymer chains relaxation. The drug is released under the effects of two phenomena: diffusion and relaxation of polymeric chains. Thus, the kinetic release passes from the kinetics of case II towards Fickian diffusion

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

Etude de l'influence des facteurs de formulation sur les propriétés viscoélastiques d'un gel à base de Carbopol

Le carbopol est un polymère souvent utilise comme agent viscosifiant et stabilisant clans la formulation des produits pharmaceutiques et cosmétiques. Il est introduit sous forme de gel, avec les autres excipients pour conférer au produit l'aspect semi-solide. Ses propriétés rhéologiques, en matière de consistance et de cohésion, sont très sensibles aux facteurs de formulation, à la concentration du carbopol et au procède de fabrication à savoir, la température et la vitesse d'agitation. Ainsi, on s'est propose clans le cadre de ce travail d'effectuer une étude de débroussaillage des différents facteurs de contrôle lies au procède de formulation, en déterminant leur influence sur les caractéristiques viscoélastiques.Mots clés: Carbopol- Gel-Formulation -Interactions- Viscoélasticité -Plans d'expériences. Carbopol is a polymer often used as viscosifying and stabilizing agent in the pharmaceutical and cosmetic product formulations. It is introduced in the form of a gel, with the others ingredients to confer a semi-solid aspect to the product. Its rheological properties, such as consistency and cohesion, are very sensitive to the formulation factors, carbopol concentration and manufacturing processes, such as temperature and stirring velocity. Thus, the aim of this work is to investigate the effects of controlling factors on the viscoelastic properties of a gel formulated with carbopol.Keywords: Carbopol - Gel - Formulation - Interactions - Viscoelasticity - Experimental design

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

Propriétés physicochimiques et rhéologiques d’un mélange aqueux de biopolymères et d’un tensioactif non ionique

Dans ce travail, on s‟intéresse à l‟effet des concentrations du xanthane, du caséinate de sodium et du tween 20 sur les propriétés rhéologiques, zétamétriques et de surface de leurs mélanges, dans un milieu aqueux à pH neutre. Il a été mis en évidence, à l‟issue de l‟utilisation de la méthodologie des plans d‟expériences, de l‟existence des interactions répulsives de ségrégation entre les biopolymères, générant un affaiblissement du module de conservation viscoélastique, G‟o et par la même une fragilisation de la structure du système colloïdal. Dans cette situation, il a été observé que le potentiel zêta diminue, ce qui laisse supposer que les interactions répulsives électrostatiques entre les deux espèces anioniques ne sont pas responsables du relâchement de la structure. Par ailleurs, il a été observé que la tension de surface du mélange dépend essentiellement de la concentration du tween 20.Mots clés :Biopolymères - Tween 20 – Rhéologie - Tension de surface - Potentiel zêta

Efficiency of Hydrogen Peroxide and Fenton Reagent for Polycyclic Aromatic Hydrocarbon Degradation in Contaminated Soil: Insights from Experimental and Predictive Modeling

\ua9 2024 by the authors.This study investigates the degradation kinetics of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil using hydrogen peroxide (H2O2) and the Fenton process (H2O2/Fe2+). The effect of oxidant concentration and the Fenton molar ratio on PAH decomposition efficiency is examined. Results reveal that increasing H2O2 concentration above 25 mmol/samples leads to a slight increase in the rate constants for both first- and second-order reactions. The Fenton process demonstrates higher efficiency in PAH degradation compared to H2O2 alone, achieving decomposition yields ranging from 84.7% to 99.9%. pH evolution during the oxidation process influences PAH degradation, with alkaline conditions favoring lower elimination rates. Fourier-transform infrared (FTIR) spectroscopy analysis indicates significant elimination of PAHs after treatment, with both oxidants showing comparable efficacy in complete hydrocarbon degradation. The mechanisms of PAH degradation by H2O2 and the Fenton process involve hydroxyl radical formation, with the latter exhibiting greater efficiency due to Fe2+ catalysis. Gaussian process regression (GPR) modeling accurately predicts reduced concentration, with optimized ARD-Exponential kernel function demonstrating superior performance. The Improved Grey Wolf Optimizer algorithm facilitates optimization of reaction conditions, yielding a high degree of agreement between experimental and predicted values. A MATLAB 2022b interface is developed for efficient optimization and prediction of C/C0, a critical parameter in PAH degradation studies. This integrated approach offers insights into optimizing the efficiency of oxidant-based PAH remediation techniques, with potential applications in contaminated soil remediation

Formulation and Characterization of Double Emulsions W/O/W Stabilized by Two Natural Polymers with Two Manufacturing Processes (Comparative Study)

\ua9 2024 by the authors.Four distinct types of multiple emulsions were synthesized using xanthan gum and pectin through two distinct manufacturing processes. The assessment encompassed the examination of morphology, stability, and rheological properties for the resulting water-in-oil-in-water (W/O/W) double emulsions. Formulations were meticulously crafted with emulsifiers that were compatible with varying compositions. Remarkably stable multiple emulsions were achieved with a 0.5 wt% xanthan concentration, demonstrating resilience for nearly two months across diverse storage temperatures. In contrast, multiple emulsions formulated with a higher pectin concentration (2.75 wt%) exhibited instability within a mere three days. All multiple emulsions displayed shear-thinning behavior, characterized by a decline in apparent viscosity with escalating shear rates. Comparatively, multiple emulsions incorporating xanthan gum showcased elevated viscosity at low shear rates in contrast to those formulated with pectin. These results underscore the pivotal role of the stepwise process over the direct approach and emphasize the direct correlation between biopolymer concentration and emulsion stability. This present investigation demonstrated the potential use of pectin and xanthan gum as stabilizers of multiple emulsions with potential application in the pharmaceutical industry for the formulation of topical dosage forms

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

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