Extraction of Organic-Free Water from Detergent Stabilized Emulsion

Abstract

We report two processes that enable continuous extraction of organic-free water from detergent stabilized oil-in-water emulsions. The first process is based upon a modification of the so-called "electrocoagulation", which uses electrochemically produced metal hydroxides that remove oil droplets via heterocoagulation. In this method, metal particles are deposited over a graphite anode, whereas an aluminum tube is used as a cathode in an electrolysis cell through which the emulsion flows. With an electrical potential applied between the graphite and aluminum, the metal particles are corroded to produce metal hydroxides that sweep the oil droplets from the emulsion. The study shows that the oil extraction efficiency increases with the basicity of the metal hydroxide. A second process, based on acid−base interaction as well, uses surface functionalization of nickel particles (∼45 μm) that introduces amines onto the nickel surface. Here an additional advantage is that the metal particles bound to the oil droplets can be removed from the aqueous phase with a magnetic field. While each of the above processes is effective in demulsifying water, their combination vastly improves the oil extraction efficiency. With the integrated process, the total organic content of the treated water could be as low as about 0.1 ppm with the surface tension of water (72 mN/m) being that of organic-free water.

Wax-wetting sponges for oil droplets recovery from frigid waters

“…Relative to freshwater, SEnS-P has exhibited a slightly higher oil mass uptake of 1182 mg g −1 and a higher rate constant of 2.78 × 10 −4 mg g −1 min −1 (table S7). The increase in the adsorption kinetics is attributed to enhanced ES attraction interactions between the oil droplets and SEnS-P through Na + and Cl − ionic charges (38)(39)(40).…”

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification

“…While in certain applications, long-time stability of these emulsions is desired, it can also be a nuisance in other situations. Stable emulsions cause concerns − in various wastewater treatments as the removal of oil-free water is expensive and becomes technically challenging. Understanding the causes underlying the formation of such emulsions should provide strategies to counter it, thus relieving some of the efforts required to purify oil-contaminated water.…”

“…One key parameter that enters in the emulsification process is the interfacial tension of the oil and water in the presence of a surfactant, which can be measured using one of the many standard methods. − ,,,,,− In the absence of agitation, the interfacial tension progresses slowly to a stable value, which is attributed to the diffusion and surface reorganization kinetics. While such types of data are useful for the properties of emulsions in an undisturbed situation, dynamic interfacial tension should play an important role when the interface fluctuates rapidly, as in turbulence.…”

Spontaneous Emulsification: Elucidation of the Local Processes

“…In our previous publications, we primarily focused on emulsification under agitated conditions. 15,18 Here, we pay attention to what happens without external agitation. What has been immensely useful in interrogating the dynamic and self-organizing behaviors of the surfactants is to exploit a property of the surfactant that reports the states in which they are in and that evolve with time.…”