Induction and Coverage Times for Crude Oil Droplets Spreading on Air Bubbles

Abstract

The interactions between crude oil droplets and air bubbles were studied by the droplet-bubble micromanipulator technique. Eight crude oils were investigated, and some aspects of the involved mechanisms were discussed. The induction time was measured for air bubbles approaching crude oil droplets in different aqueous phases. Distinct differences were observed in the presence and absence of salts, which showed the importance of long-ranged electrostatic repulsive forces on thin-film stability. The results also suggested that adsorption of dissolved hydrocarbons at air bubble surfaces may increase the potential energy barrier in the thin liquid film. Furthermore, the time needed for crude oil droplets to spread over the air bubble surfaces (referred to as coverage time) was determined for the crude oils. The results showed that the spreading velocity decreased with increasing viscosity of the crude oil. The detailed understanding of this type of interaction is considered to be a precursor for improving the oil removal efficiency during the flotation process.

Composition and Dynamic Adsorption of Crude Oil Components Dissolved in Synthetic Produced Water at Different pH Values

“…In this work it was demonstrated that the amount, type, and surface affinity of water-soluble components in synthetic produced water were influenced by pH (reflecting pressure differences) of the aqueous solutions. Previously it was shown that water-soluble crude oil components prolonged the drainage time of the aqueous film between bubbles and drops, 24 and subsequently this reduced the removal efficiency of dispersed oil from produced water during gas flotation. 25 Consequently, it seems reasonable to anticipate that conditions giving rise to differences in surface pressure can influence the extent of oil removal during gas flotation.…”

“…Furthermore, the drainage and rupture of the thin aqueous film formed upon the close approach of a single bubble and a single crude oil drop were studied in a drop-bubble micromanipulator system. 24 It was shown that the adsorption of hydrocarbons onto gas bubbles increased the drainage time of the film between bubbles and drops and thereby influenced the attachment between bubbles and drops. It was also shown in both laboratory and pilot scale flotation studies that the adsorption of the water-soluble crude oil components onto bubble surfaces reduced the removal efficiency of dispersed oil from water by gas flotation.…”

“…This demonstrated that detailed knowledge about the crude oil fractions and the water phase could give good predictions of the interfacial properties of gas bubbles. Furthermore, the drainage and rupture of the thin aqueous film formed upon the close approach of a single bubble and a single crude oil drop were studied in a drop-bubble micromanipulator system . It was shown that the adsorption of hydrocarbons onto gas bubbles increased the drainage time of the film between bubbles and drops and thereby influenced the attachment between bubbles and drops.…”

Theoretical and Experimental Investigation of Film Drainage Time

“…Details of the experimental set-up and methodology are further described by Eftekhardadkhah and Oye [14]. The experimental set-up applied by Eftekhardadkhah and Oye [14] is motivated by the work by Won et al [15]. The type of raw data obtained with the micromanipulator is shown in Fig.…”

Description of Disperse Multiphase Processes: Quo Vadis?

“…The collision and coalescence of two bubbles or droplets and the formation of a dimple, bridge and film rupture can be evaluated with external high‐speed cameras . Therefore, both droplets can be attached to cannulas and brought in contact which allows for a detailed analysis of the film drainage and development of the liquid bridge during coalescence , . The collision of a rising or falling particle with a particle fixed by a cannula has the advantage that the relative collision velocity as well as the effect of impact location can be analyzed and used to achieve information on the coalescence efficiency (Fig.…”