Facile fabrication of superhydrophilic membranes consisted of fibrous tunicate cellulose nanocrystals for highly efficient oil/water separation

Faced on the threat of oil-contaminated wastewater to the environment and health of human body, we demonstrated, for the first time, a facile method for fabrication of novel nanoporous cellulose membranes derived from renewable marine resources (shell of tunicate). The fibrous tunicate cellulose nanocrystals (TCNCs) were prepared by acid hydrolysis, and exhibited high degree of crystallinity and distinct cholesteric liquid crystal behavior. Thus, the TCNC membranes were constructed by vacuum-assisted filtration of TCNCs suspensions, showing hierarchical structure, and superhydrophilic/underwater superoleophobic characters. The experimental results confirmed that the TCNC membranes were beneficial for highly efficient separation of oily water, which not only could separate various oil-in-water nanoemulsions, but also were applicable for oil-in water microemulsions and water-in-oil emulsions. The thickness, pore size, water flux, and oil rejection of the TCNC membranes could be controlled by the dosage of TCNCs. Moreover, they exhibited high mechanical strength, excellent pH- and temperature-stability, and good cycling performance. On the basis of the combining of cholesteric liquid crystal structure and superhydrophilicity of fibrous tunicate cellulose nanocrystals, a new strategy to construct novel filter membranes for the highly effective oil/water separation was provided here.