Scalable production of functional Janus particles in 3D printed microfluidic device for heavy oil removal*

Microfluidic droplet generators can produce droplets and particles of uniform size and varying morphologies. However, due to the low throughput, production scale-up through device parallelization is essential to apply them practically. While high-level microfabrication techniques have been required to fabricate parallelized devices, the advent of 3D printing has enabled the fabrication of devices with complex 3D channel structures at a low cost and with minimal effort. In this study, we designed and fabricated a parallelized and multiplexed droplet generator that can produce amphiphilic magnetic Janus particles (AMJPs) at a rate 40 times faster than a single device while maintaining monodispersity and uniformity. In this device, each droplet generator is connected via flow distributors, which achieve uniform flow distribution and minimizes device volume. The resulting AMJPs can be irreversibly adsorbed at the interface, effectively Pickering emulsifying oil contaminants in water and preventing further contamination. The effects of oil viscosity, water pH, and salinity on the size and removal rate of AMJPs-covered Pickering emulsion were experimentally investigated. Furthermore, the effectiveness and reusability of AMJPs in removing heavy crude oil were demonstrated.