Sequential Demulsification through the Hydrophobic-Hydrophilic-Hydrophobic Filtration Layer toward High-Performing Oil Recovery

This work demonstrates a 3H trilayermembrane that enablesthe effective demulsification of O/W emulsions with high flux. Demulsification using membranes is a promising methodto coalescehighly stable emulsified oil droplets for oil recovery. Nevertheless,a structure of the current filtration medium that is not efficientfor oil droplet coalescence impedes rapid permeability, thereby inevitablyrestricting their practical applications. Herein, we report a hydrophobic-hydrophilic-hydrophobic(3H) demulsification medium that exhibits a benchmark permeabilityof & SIM;2.1 x 10(4) L m(-2) h(-1) with a demulsification efficiency of >98.0%. Remarkably,this 3H demulsification medium maintains over 90% demulsificationefficiency in the oil-in-water (O/W) emulsions with a wide range ofsurfactant concentrations, which shows excellent applicability. Basedon the combined results of quasi situ microscopeimages and molecular dynamics simulations, we show that the polydimethylsiloxane-modifiedhydrophobic layer facilitates the capture and coalescence of oil droplets,the hydrophilic inner layer assists in squeezing the coalescence ofenlarged droplets, and the third hydrophobic layer accelerates thedischarge of demulsified oil to sustain permeability. The sequentialdemulsification mechanism between this 3H filtration layer providesa general guide for designing a demulsifying membrane with high demulsificationefficiency and high flux toward oil recovery.

Automated summary

This work presents a 3H trilayer membrane that efficiently breaks oil-in-water emulsions with high permeability. The hydrophobic-hydrophilic-hydrophobic (3H) structure allows for the capture, coalescence, and discharge of oil droplets, resulting in a demulsification efficiency of over 98.0% and a permeability of 2.1 x 10(4) L m(-2) h(-1). The 3H membrane maintains its high demulsification efficiency across a wide range of surfactant concentrations, making it highly applicable for oil recovery.