(732d) Enhanced Liquid-Liquid Separation Using a 3D-Printed 2-Dimensional Device with Advanced Coatings

Wastewater treatment remained critical for the chemical industry in general. Application and adoption of intensified process design and 3D-printed devices offer the prospect of revolutionizing the oil-water separation. A 3D-printed device that takes the advantage of potential reduced size, increased scalability of equipment, and process intensification through faster extraction and phase separation at a lower energy cost could be highly amenable to modular chemical manufacturing. To this interest, our collaborators from Oregon State University designed a 3D-printable liquid-liquid separation device for oil-water phase separation via guiding the mixture flow through a capillary force gradient 'field'. The operation is designed to not allow a selected phase to overcome capillary interface forces with inertial and viscous forces, thus guiding the fluid towards only one outlet stream. To further improve the separation efficiency, we have designed and fabricated the coatings with the desired wettability gradient, i.e., from hydrophilicity/oleophobicity at one end to hydrophobicity/oleophilicity at the other end. Simultaneous hydrophilicity/oleophobicity has been achieved with Perfluoropolyethers (PFPEs) coating on glass slides. A lower water contact angle (WCA) of < 30° and a higher hexadecane contact angle (HCA) of > 65° were obtained. In addition, such coating is durable after 100-hour immersion in water and organic solvents, evidenced by the unchanged HCA and coating thickness. Meanwhile, simultaneously hydrophobic/oleophilic surface coating has been achieved with chloro(dodecyl)dimethylsilane-based SAMs, where WCA is 90° and HCA is below 10°. This coating is also stable after 100-hour immersion in water and organic solvents. Our work demonstrates the potential of the advanced coatings in application of liquid-liquid separation.