L'extraction aqueuse des lipides de la graine de tournesol est étudiée en contacteur agité. La diffusion à l'intérieur des particules est le facteur limitant de l'échange de matière. Les protéines sont impliquées dans l'entraînement et la stabilisation des lipides par l'eau. Le fractionnement de la plante entière est également étudié avec l'eau en extrusion bi-vis. Un extrait et un raffinat sont obtenus séparément et en une seule étape continue. Des rendements d'extraction en huile de 55 % peuvent être obtenus sous forme d'émulsions huile/eau. Leur stabilité est assurée par la présence à l'interface de tensioactifs : les phospholipides et les protéines voire les pectines. Les extraits se composent aussi d'une phase hydrophile. Prépondérante, elle contient des composés hydrosolubles (protéines, pectines…). Riches en fibres, les raffinats présentent une teneur significative en protéines au comportement thermoplastique. Ils peuvent être transformés en agromatériaux par thermomoulage.

<p>Emulsions are advantageous in many applications including healthcare, food science, and detergency due to their ability to disperse one fluid in another, otherwise immiscible fluid. For the same reason, emulsions are also problematic when mixtures of oil and water are undesirable like in industrial wastewater pollution and fuel systems. Whether an emulsion is desirable or not, both benefit from understanding the fundamental relationship of emulsion formation and stability to the physical and chemical properties of the oil-water-surfactant mixture. This work identifies the formation and stability mechanisms of model emulsion systems through the perspective of emulsion prevention for applications in shipboard wastewater (bilge water) treatment. Although experiments in this study were designed to model bilge water systems, their fundamental approach makes them practical for many different applications like food science, pharmaceuticals, and detergency.</p> <p>The impact of salts on emulsion formation and stability to coalescence were studied to understand how emulsions stabilized by ionic surfactant behave in saltwater environments. Droplet size analysis revealed that emulsion stability to coalescence improved with salt concentration. Through interfacial tension and zeta potential measurements, it was found that the addition of salt promoted close surfactant packing and faster surfactant adsorption kinetics at the oil-water interface. This aided in preventing coalescence and created conditions favorable for the formation of a stable Newton black film. Extended DLVO calculations were used to model the interaction energy between droplets and suggested that hydration forces play an important role in stabilizing these systems. These emulsions were then studied under dynamic ageing conditions to observe the impact of motion on emulsion stability. While statically aged emulsions were stable to coalescence, dynamic ageing induced coalescence (increased droplet size) or emulsified the oil droplets (decreased droplet size) depending on the surfactant concentration and energy input during ageing.</p> Formation mechanisms and stability of spontaneous emulsion systems were also investigated. Low molecular weight oils (e.g., toluene, xylenes, and cyclohexane) were found to spontaneously emulsify with nonylphenol polyethoxylated (NPE) and sodium dodecylbenzene sulfonate (SDBS). NPE emulsions spontaneously emulsified via diffusion and micelle swelling and displayed limited stability due to Ostwald ripening. SDBS emulsions also spontaneously emulsified with toluene but only in saltwater environments. As the concentration of salt in the aqueous phase increased, the spontaneity of these emulsions also increased. These systems were analyzed using the hydrophilic lipophilic difference (HLD) theory to evaluate its efficacy for predicting the conditions favorable for spontaneous emulsification. Limitations and practicality of using the HLD model for these systems were also explored.