Charge-Induced Aggregation of Emulsified Oil Droplets in Water with Presence of Functionalized Stainless Steel Felt

Abstract

Oil-water mixtures, especially the surfactant-stabilized oil-in-water emulsions with high stability, are causing great difficulties for effective separation. In this work, a modification strategy was proposed to prepare functionalized stainless steel felt for emulsion separation by coating the felt with 3-triethoxysilylpropylamine, followed by the introduction of silica nanoparticles using a sulfur-based three-component coupling reaction. To satisfy the pore size requirement for effective emulsion separation, the developed felt was processed using a compression molding. With special wettability, optimized pore size, and electrostatic demulsification mechanism, the positive charged felt delivered outstanding separation capabilities for oil-in-water emulsions stabilized by various surfactants. Specifically, the flux and COD removal efficiency for the anionic-stabilized emulsion were up to 3911 L/m2/h and 95.3%, while for cationic-stabilized emulsions, which were 1305 L/m2/h and 93.1%. The results indicated that surface charges played an important role in governing the separation performance of the felt, and the electrostatic attraction demulsification demonstrated better separation capabilities than that from the electrostatic repulsion process.

Keywords: Sulfur-based three-component reaction, surface modification, Emulsion separation, Electrostatic demulsification