Enhanced demulsification performance of microchannel walls with slots patterned wettability surface

Microchannel demulsification is an emerging separation process for the efficient disposal of oily wastewater and oil phase recovery. Currently, this technology focuses on improving the single-pass demulsification efficiency with a short residence time. In this study, a hydrophobic/hydrophilic slots pattern was fabricated on a microchannel bottom wall to improve the single-pass demulsification efficiency through microfluidic field disturbance. The effects of the wall wettability and pattern size on the demulsification performance were studied. The adsorption, coalescence, and desorption of the oil droplets flowing through the patterned walls, and resulting microfluidic disturbances were analyzed by numerical simulation. The optimized microchannel had an enhanced single-pass demulsification efficiency of 40 % within a residence time of 0.25 s. The demulsification efficiency of the slots patterned plate-type microchannel wall was affected by the flow velocity, microchannel height, pattern size, and wettability. Therefore, this work elucidates on microchannel demulsification mechanisms, thereby providing new ideas for enhanced performance.