Heterogeneous wettable microchannel for enhancing demulsification and separation of oil-in-water emulsions

The development of efficient oil-water separation technology has gained significant importance in environmental pollution control and resource recovery. Inspired by the hydrophilic/superhydrophobic patterned surface of Namib Desert Beetles, this study designs a grid-like heterogeneous wettable microchannel device (HWMD) by fabricating heterogeneous wettable plates with tunable wettable patterns. The HWMD combines wettability gradient regulation, spatial confinement, and flow field control to enhance the coalescence-collection of oil droplets, enabling demulsification and separation of oil-in-water (O/W) emulsions. The experimental results revealed that under a flow rate of 3 mL/min and a channel height of 500 μm, the HWMD successfully separated various surfactant-stabilized O/W emulsions, reducing the oil content in the filtrate to a range of 32‐80 mg/L after recycling, though its capture efficiency was reduced for droplets smaller than 15 μm. The simple preparation process and independent operation capability of HWMD provide a practical and efficient strategy for the optimization of separators, demonstrating considerable potential for industrial applications.