Critical Review of Electro-Coalescence for the Separation of Water/Oil Emulsions

Electro-coalescence is an environmentally benign and energy-efficient demulsification method widely used in the petroleum sector. Improving its performance requires accelerating emulsion separation while maintaining operational safety. However, existing review articles often lack comprehensive coverage of the current state of the art. This critical review addresses this gap by providing a detailed technical examination of electro-coalescence, a rapidly evolving area of research. The paper synthesizes current understanding and recent developments in the field, with emphasis on the key parameters and underlying physicochemical phenomena that govern electro-coalescence performance. Specifically, we review electrode geometries; methods for applying electric fields, including DC and AC modes with attention to waveform effects; numerical and molecular-scale modeling approaches; hybrid separation strategies; and existing commercial technologies and configurations. Additionally, we addressed topics related to operational challenges, such as fouling and current bridging, and future trends such as digital twins and machine learning in electro-coalescence. This study provides an integrated and thorough assessment of current knowledge and technological advancements, identifies outstanding research possibilities, and suggests strategies for optimizing electro-coalescence processes through a critical analysis of literature.