(408d) 3D-Printed Membranes with a Zwitterionic Hydrogel Coating for More Robust Oil-Water Separation

Oil-water separation is a key step in the purification of industrial oily wastewater, which is a worldwide challenge giving rise to negative impacts on human health and ecosystems. 3D-printed membranes via stereolithography (SLA) are promising for oil-water separation due to the high resolution in fabricating parts with various shapes and structures. To achieve gravity-driven oil-water separation, a simultaneously hydrophilic/oleophobic membrane material is required. However, most of the state-of-the-art materials for SLA are oleophilic. While water-adsorbing hydrogel is simultaneously hydrophilic/oleophobic and there have been 3D-printed hydrogels in biomedical applications, the hydrogel is too soft for membrane application. In this work, we report a simple approach to solve this issue: a zwitterionic hydrogel coating on SLA-based plastic membranes. This coating is fabricated, using [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide as the zwitterionic monomer and acrylamide as the comonomer, via in situ polymerization on plastic membranes. The contact angle measurements and Fourier transform infrared spectrum show that the hydrogel-coated membrane readily adsorbs water and becomes simultaneously hydrophilic/oleophobic. The oil-water separation tests demonstrate that the water-adsorbed membrane is highly efficient in gravity-driven oil-water separation in 31 repeating cycles. These outcomes indicate the great potential of 3D-printed membranes in oil-water separation.