Fabrication of cellulose nanofiber-deposited cellulose sponge as an oil-water separation membrane

A cellulose sponge was fabricated through xanthation to dissolve cellulose, and heating to regenerate the cellulose solution. The obtained cellulose sponge showed good physical strength with resilient ratio and unrecoverable proportion at 60% compression stress of 42.6% and 25.7%, respectively. Bamboo-based counter collision cellulose nanofiber (MECH-CNF) prepared by the aqueous counter collision method and wood-free fiber-based 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized cellulose nanofiber (TEMPO-CNF) were used to increase the hydrophilicity and underwater oleophobicity of the cellulose sponge. Oil contact angles in air and underwater were investigated to evaluate oleophobicity. The TEMPO-CNF-deposited cellulose sponge (TCNF-membrane) demonstrated higher oleophobicity underwater than MECH-CNF-deposited cellulose sponge (MCNF-membrane). Oil-water separation was tested to evaluate the possibility of water treatment applications. The flowrate of the MCNF-membrane was 3.73 x 10(3) L m(-2) h(-1) and much higher than that of the TCNF-membrane at 166 L m(-2) h(-1), both at separation efficiency levels higher than 99% by gravitational force alone.