Nano graphene oxide creates a fully biobased 3D-printed membrane with high-flux and anti-fouling oil/water separation performance

Facile fabrication of green and renewable bio-based membranes with good anti-fouling and oil/water separation performance is of great importance to solve the oil spills and industrial oily wastewater threatening the ecological environment. Here, a fully biobased oil/water separation membrane with an ordered porous structure was 3D printed ultraviolet-assisted direct ink writing. The components of the bio-ink were obtained by methacrylation of chitosan (CS) and gelatin (GEL) to synthesize methacrylated chitosan (CSMA) and methacrylated gelatin (GELMA), while the nanographene oxide (nGO) was derived from CS through a simple microwave-assisted hydrothermal carbonization followed by oxidation step. The addition of nGO boosted the printability of the bio-ink, and the anti-fouling property and water permeation flux of the printed membranes. As a result, the membrane M−CSMA/GELMA/nGO-0.7 with the optimal performance possessed a low water contact angle in air of 0°, and high underwater oil contact angle of 161.5°, demonstrating a combination of superhydrophilic and underwater superoleophobic properties. M−CSMA/GELMA/nGO-0.7 has good corrosion resistance and long service life as evidenced from the separation efficiency of n-heptane/water, which kept above 99.5 % and a high water permeation flux above 38,300 L m−2h−1 after 20 cyclic tests in the harsh aquatic conditions containing 1 M NaCl, 1 M HCl, or 1 M NaOH, respectively. This shows promising potential for real-life applications.