Additive Printed All-Cellulose Membranes with Hierarchical Structure for Highly Efficient Separation of Oil/Water Nanoemulsions.

To expand the application of commercial membranes in oily wastewater separation, in this work, all-cellulose membranes were fabricated by depositing cellulose nanocrystals onto the surface of mixed-cellulose esters via a large-scale additive printing strategy. The thickness, pore size, surface wettability, and water flux of all-cellulose membranes can be well tuned by controlling the printing cycles of cellulose nanocrystal inks. Under optimal printing conditions, the resultant all-cellulose membranes with nanoporous architecture (76-91 nm) exhibit superhydrophilicity and underwater superoleophobicity, which benefits the separation of oil/water nanoemulsions with a high water flux (>1500 L m-2 h-1 bar-1) and an ultrahigh efficiency (>99%). Moreover, these all-cellulose membranes exhibit excellent stability and reusability for long-term separation and retains their inherent properties under various acidic, basic, and salty conditions, as well as mechanical abrasion. The presented scalable additive printing is a facile, economical, and sustainable strategy to construct all-cellulose membranes with excellent separation performance for oil/water nanoemulsions.